No Reef Is an Island: Integrating Coral Reef Connectivity Data into the Design of Regional-Scale Marine Protected Area Networks.

PubMed

Schill, Steven R; Raber, George T; Roberts, Jason J; Treml, Eric A; Brenner, Jorge; Halpin, Patrick N

2015-01-01

We integrated coral reef connectivity data for the Caribbean and Gulf of Mexico into a conservation decision-making framework for designing a regional scale marine protected area (MPA) network that provides insight into ecological and political contexts. We used an ocean circulation model and regional coral reef data to simulate eight spawning events from 2008-2011, applying a maximum 30-day pelagic larval duration and 20% mortality rate. Coral larval dispersal patterns were analyzed between coral reefs across jurisdictional marine zones to identify spatial relationships between larval sources and destinations within countries and territories across the region. We applied our results in Marxan, a conservation planning software tool, to identify a regional coral reef MPA network design that meets conservation goals, minimizes underlying threats, and maintains coral reef connectivity. Our results suggest that approximately 77% of coral reefs identified as having a high regional connectivity value are not included in the existing MPA network. This research is unique because we quantify and report coral larval connectivity data by marine ecoregions and Exclusive Economic Zones (EZZ) and use this information to identify gaps in the current Caribbean-wide MPA network by integrating asymmetric connectivity information in Marxan to design a regional MPA network that includes important reef network connections. The identification of important reef connectivity metrics guides the selection of priority conservation areas and supports resilience at the whole system level into the future.

No Reef Is an Island: Integrating Coral Reef Connectivity Data into the Design of Regional-Scale Marine Protected Area Networks

PubMed Central

Schill, Steven R.; Raber, George T.; Roberts, Jason J.; Treml, Eric A.; Brenner, Jorge; Halpin, Patrick N.

2015-01-01

We integrated coral reef connectivity data for the Caribbean and Gulf of Mexico into a conservation decision-making framework for designing a regional scale marine protected area (MPA) network that provides insight into ecological and political contexts. We used an ocean circulation model and regional coral reef data to simulate eight spawning events from 2008–2011, applying a maximum 30-day pelagic larval duration and 20% mortality rate. Coral larval dispersal patterns were analyzed between coral reefs across jurisdictional marine zones to identify spatial relationships between larval sources and destinations within countries and territories across the region. We applied our results in Marxan, a conservation planning software tool, to identify a regional coral reef MPA network design that meets conservation goals, minimizes underlying threats, and maintains coral reef connectivity. Our results suggest that approximately 77% of coral reefs identified as having a high regional connectivity value are not included in the existing MPA network. This research is unique because we quantify and report coral larval connectivity data by marine ecoregions and Exclusive Economic Zones (EZZ) and use this information to identify gaps in the current Caribbean-wide MPA network by integrating asymmetric connectivity information in Marxan to design a regional MPA network that includes important reef network connections. The identification of important reef connectivity metrics guides the selection of priority conservation areas and supports resilience at the whole system level into the future. PMID:26641083

Modeled differences of coral life-history traits influence the refugium potential of a remote Caribbean reef

NASA Astrophysics Data System (ADS)

Davies, Sarah W.; Strader, Marie E.; Kool, Johnathan T.; Kenkel, Carly D.; Matz, Mikhail V.

2017-09-01

Remote populations can influence connectivity and may serve as refugia from climate change. We investigated two reef-building corals ( Pseudodiploria strigosa and Orbicella franksi) from the Flower Garden Banks (FGB), the most isolated, high-latitude Caribbean reef system, which, until recently, retained high coral cover. We characterized coral size-frequency distributions, quantified larval mortality rates and onset of competence ex situ, estimated larval production, and created detailed biophysical models incorporating these parameters to evaluate the source-sink dynamics at the FGB from 2009 to 2012. Estimated mortality rates were similar between species, but pre-competency differed dramatically; P. strigosa was capable of metamorphosis within 2.5 d post-fertilization (dpf) and was competent at least until 8 dpf, while O. franksi was not competent until >20 dpf and remained competent up to 120 dpf. To explore the effect of such contrasting life histories on connectivity, we modeled larval dispersal from the FGB assuming pelagic larval durations (PLD) of either 3-20 d, approximating laboratory-measured pre-competency of P. strigosa, or 20-120 d, approximating pre-competency observed in O. franksi. Surprisingly, both models predicted similar probabilities of local retention at the FGB, either by direct rapid reseeding or via long-term persistence in the Loop Current with larvae returning to the FGB within a month. However, our models predicted that short PLDs would result in complete isolation from the rest of the Caribbean, while long PLDs allowed for larval export to more distant northern Caribbean reefs, highlighting the importance of quantifying larval pre-competency dynamics when parameterizing biophysical models to predict larval connectivity. These simulations suggest that FGB coral populations are likely to be largely self-sustaining and highlight the potential of long-PLD corals, such as endangered Orbicella, to act as larval sources for other degraded Caribbean reefs.

Factors affecting infection of corals and larval oysters by Vibrio coralliilyticus.

PubMed

Ushijima, Blake; Richards, Gary P; Watson, Michael A; Schubiger, Carla B; Häse, Claudia C

2018-01-01

The bacterium Vibrio coralliilyticus can threaten vital reef ecosystems by causing disease in a variety of coral genera, and, for some strains, increases in virulence at elevated water temperatures. In addition, strains of V. coralliilyticus (formally identified as V. tubiashii) have been implicated in mass mortalities of shellfish larvae causing significant economic losses to the shellfish industry. Recently, strain BAA-450, a coral pathogen, was demonstrated to be virulent towards larval Pacific oysters (Crassostrea gigas). However, it is unclear whether other coral-associated V. coralliilyticus strains can cause shellfish mortalities and if infections are influenced by temperature. This study compared dose dependence, temperature impact, and gross pathology of four V. coralliilyticus strains (BAA-450, OCN008, OCN014 and RE98) on larval C. gigas raised at 23°C and 27°C, and evaluated whether select virulence factors are required for shellfish infections as they are for corals. All strains were infectious to larval oysters in a dose-dependent manner with OCN014 being the most pathogenic and BAA-450 being the least. At 27°C, higher larval mortalities (p < 0.05) were observed for all V. coralliilyticus strains, ranging from 38.8-93.7%. Gross pathological changes to the velum and cilia occurred in diseased larvae, but there were no distinguishable differences between oysters exposed to different V. coralliilyticus strains or temperatures. Additionally, in OCN008, the predicted transcriptional regulator ToxR and the outer membrane protein OmpU were important for coral and oyster disease, while mannose sensitive hemagglutinin type IV pili were required only for coral infection. This study demonstrated that multiple coral pathogens can infect oyster larvae in a temperature-dependent manner and identified virulence factors required for infection of both hosts.

The recovery of coral genetic diversity in the Sunda Strait following the 1883 eruption of Krakatau

NASA Astrophysics Data System (ADS)

Starger, C. J.; Barber, P. H.; Ambariyanto; Baker, A. C.

2010-09-01

Surveys of microsatellite variation show that genetic diversity has largely recovered in two reef-building corals, Pocillopora damicornis and Seriatopora hystrix (Scleractinia: Pocilloporidae), on reefs which were decimated by the eruption of the volcano Krakatau in 1883. Assignment methods and gene flow estimates indicate that the recolonization of Krakatau occurred mainly from the closest upstream reef system, Pulau Seribu, but that larval input from other regions has also occurred. This pattern is clearer in S. hystrix, which is traditionally the more dispersal-limited species. Despite these observed patterns of larval dispersal, self-recruitment appears to now be the most important factor in supplying larvae to coral populations in Krakatau. This suggests that the colonization of devastated reefs can occur quickly through larval dispersal; however, their survival requires local sources of larvae for self-recruitment. This research supports the observation that the recovery of genetic diversity in coral reef animals can occur on the order of decades and centuries rather than millennia. Conservation measures aimed at sustaining coral reef populations in Krakatau and elsewhere should include both the protection of upstream source populations for larval replenishment should disaster occur as well as the protection of large adult colonies to serve as local larval sources.

Ocean acidification reduces coral recruitment by disrupting intimate larval-algal settlement interactions.

PubMed

Doropoulos, Christopher; Ward, Selina; Diaz-Pulido, Guillermo; Hoegh-Guldberg, Ove; Mumby, Peter J

2012-04-01

Ecology Letters (2012) 15: 338-346 ABSTRACT: Successful recruitment in shallow reef ecosystems often involves specific cues that connect planktonic invertebrate larvae with particular crustose coralline algae (CCA) during settlement. While ocean acidification (OA) can reduce larval settlement and the abundance of CCA, the impact of OA on the interactions between planktonic larvae and their preferred settlement substrate are unknown. Here, we demonstrate that CO2 concentrations (800 and 1300 μatm) predicted to occur by the end of this century significantly reduce coral (Acropora millepora) settlement and CCA cover by ≥ 45%. The CCA important for inducing coral settlement (Titanoderma spp., Hydrolithon spp.) were the most deleteriously affected by OA. Surprisingly, the only preferred settlement substrate (Titanoderma) in the experimental controls was avoided by coral larvae as pCO2 increased, and other substrata selected. Our results suggest OA may reduce coral population recovery by reducing coral settlement rates, disrupting larval settlement behaviour, and reducing the availability of the most desirable coralline algal species for successful coral recruitment. © 2012 Blackwell Publishing Ltd/CNRS.

A Biophysical Model for Hawaiian Coral Reefs: Coupling Local Ecology, Larval Transport and Climate Change

NASA Astrophysics Data System (ADS)

Kapur, M. R.

2016-02-01

Simulative models of reef ecosystems have been used to evaluate ecological responses to a myriad of disturbance events, including fishing pressure, coral bleaching, invasion by alien species, and nutrient loading. The Coral Reef Scenario Evaluation Tool (CORSET), has been developed and instantiated for both the Meso-American Reef (MAR) and South China Sea (SCS) regions. This model is novel in that it accounts for the many scales at which reef ecosystem processes take place; is comprised of a "bottom-up" structure wherein complex behaviors are not pre-programmed, but emergent and highly portable to new systems. Local-scale dynamics are coupled across regions through larval connectivity matrices, derived sophisticated particle transport simulations that include key elements of larval behavior. By this approach, we are able to directly evaluate some of the potential consequences of larval connectivity patterns across a range of spatial scales and under multiple climate scenarios. This work develops and applies the CORSET (Coral Reef Scenario Evaluation Tool) to the Main Hawaiian Islands under a suite of climate and ecological scenarios. We introduce an adaptation constant into reef-building coral dynamics to simulate observed resiliencies to bleaching events. This presentation will share results from the model's instantiation under two Resource Concentration Pathway climate scenarios, with emphasis upon larval connectivity dynamics, emergent coral tolerance to increasing thermal anomalies, and patterns of spatial fishing closures. Results suggest that under a business-as-usual scenario, thermal tolerance and herbivore removal will have synergistic effects on reef resilience.

RNA-Seq of the Caribbean reef-building coral Orbicella faveolata (Scleractinia-Merulinidae) under bleaching and disease stress expands models of coral innate immunity.

PubMed

Anderson, David A; Walz, Marcus E; Weil, Ernesto; Tonellato, Peter; Smith, Matthew C

2016-01-01

Climate change-driven coral disease outbreaks have led to widespread declines in coral populations. Early work on coral genomics established that corals have a complex innate immune system, and whole-transcriptome gene expression studies have revealed mechanisms by which the coral immune system responds to stress and disease. The present investigation expands bioinformatic data available to study coral molecular physiology through the assembly and annotation of a reference transcriptome of the Caribbean reef-building coral, Orbicella faveolata. Samples were collected during a warm water thermal anomaly, coral bleaching event and Caribbean yellow band disease outbreak in 2010 in Puerto Rico. Multiplex sequencing of RNA on the Illumina GAIIx platform and de novo transcriptome assembly by Trinity produced 70,745,177 raw short-sequence reads and 32,463 O. faveolata transcripts, respectively. The reference transcriptome was annotated with gene ontologies, mapped to KEGG pathways, and a predicted proteome of 20,488 sequences was generated. Protein families and signaling pathways that are essential in the regulation of innate immunity across Phyla were investigated in-depth. Results were used to develop models of evolutionarily conserved Wnt, Notch, Rig-like receptor, Nod-like receptor, and Dicer signaling. O. faveolata is a coral species that has been studied widely under climate-driven stress and disease, and the present investigation provides new data on the genes that putatively regulate its immune system.

RNA-Seq of the Caribbean reef-building coral Orbicella faveolata (Scleractinia-Merulinidae) under bleaching and disease stress expands models of coral innate immunity

PubMed Central

Walz, Marcus E.; Weil, Ernesto; Smith, Matthew C.

2016-01-01

Climate change-driven coral disease outbreaks have led to widespread declines in coral populations. Early work on coral genomics established that corals have a complex innate immune system, and whole-transcriptome gene expression studies have revealed mechanisms by which the coral immune system responds to stress and disease. The present investigation expands bioinformatic data available to study coral molecular physiology through the assembly and annotation of a reference transcriptome of the Caribbean reef-building coral, Orbicella faveolata. Samples were collected during a warm water thermal anomaly, coral bleaching event and Caribbean yellow band disease outbreak in 2010 in Puerto Rico. Multiplex sequencing of RNA on the Illumina GAIIx platform and de novo transcriptome assembly by Trinity produced 70,745,177 raw short-sequence reads and 32,463 O. faveolata transcripts, respectively. The reference transcriptome was annotated with gene ontologies, mapped to KEGG pathways, and a predicted proteome of 20,488 sequences was generated. Protein families and signaling pathways that are essential in the regulation of innate immunity across Phyla were investigated in-depth. Results were used to develop models of evolutionarily conserved Wnt, Notch, Rig-like receptor, Nod-like receptor, and Dicer signaling. O. faveolata is a coral species that has been studied widely under climate-driven stress and disease, and the present investigation provides new data on the genes that putatively regulate its immune system. PMID:26925311

A Snapshot of a Coral “Holobiont”: A Transcriptome Assembly of the Scleractinian Coral, Porites, Captures a Wide Variety of Genes from Both the Host and Symbiotic Zooxanthellae

PubMed Central

Shinzato, Chuya; Inoue, Mayuri; Kusakabe, Makoto

2014-01-01

Massive scleractinian corals of the genus Porites are important reef builders in the Indo-Pacific, and they are more resistant to thermal stress than other stony corals, such as the genus Acropora. Because coral health and survival largely depend on the interaction between a coral host and its symbionts, it is important to understand the molecular interactions of an entire “coral holobiont”. We simultaneously sequenced transcriptomes of Porites australiensis and its symbionts using the Illumina Hiseq2000 platform. We obtained 14.3 Gbp of sequencing data and assembled it into 74,997 contigs (average: 1,263 bp, N50 size: 2,037 bp). We successfully distinguished contigs originating from the host (Porites) and the symbiont (Symbiodinium) by aligning nucleotide sequences with the decoded Acropora digitifera and Symbiodinium minutum genomes. In contrast to previous coral transcriptome studies, at least 35% of the sequences were found to have originated from the symbionts, indicating that it is possible to analyze both host and symbiont transcriptomes simultaneously. Conserved protein domain and KEGG analyses showed that the dataset contains broad gene repertoires of both Porites and Symbiodinium. Effective utilization of sequence reads revealed that the polymorphism rate in P. australiensis is 1.0% and identified the major symbiotic Symbiodinium as Type C15. Analyses of amino acid biosynthetic pathways suggested that this Porites holobiont is probably able to synthesize most of the common amino acids and that Symbiodinium is potentially able to provide essential amino acids to its host. We believe this to be the first molecular evidence of complementarity in amino acid metabolism between coral hosts and their symbionts. We successfully assembled genes originating from both the host coral and the symbiotic Symbiodinium to create a snapshot of the coral holobiont transcriptome. This dataset will facilitate a deeper understanding of molecular mechanisms of coral symbioses and stress responses. PMID:24454815

A snapshot of a coral "holobiont": a transcriptome assembly of the scleractinian coral, porites, captures a wide variety of genes from both the host and symbiotic zooxanthellae.

PubMed

Shinzato, Chuya; Inoue, Mayuri; Kusakabe, Makoto

2014-01-01

Massive scleractinian corals of the genus Porites are important reef builders in the Indo-Pacific, and they are more resistant to thermal stress than other stony corals, such as the genus Acropora. Because coral health and survival largely depend on the interaction between a coral host and its symbionts, it is important to understand the molecular interactions of an entire "coral holobiont". We simultaneously sequenced transcriptomes of Porites australiensis and its symbionts using the Illumina Hiseq2000 platform. We obtained 14.3 Gbp of sequencing data and assembled it into 74,997 contigs (average: 1,263 bp, N50 size: 2,037 bp). We successfully distinguished contigs originating from the host (Porites) and the symbiont (Symbiodinium) by aligning nucleotide sequences with the decoded Acropora digitifera and Symbiodinium minutum genomes. In contrast to previous coral transcriptome studies, at least 35% of the sequences were found to have originated from the symbionts, indicating that it is possible to analyze both host and symbiont transcriptomes simultaneously. Conserved protein domain and KEGG analyses showed that the dataset contains broad gene repertoires of both Porites and Symbiodinium. Effective utilization of sequence reads revealed that the polymorphism rate in P. australiensis is 1.0% and identified the major symbiotic Symbiodinium as Type C15. Analyses of amino acid biosynthetic pathways suggested that this Porites holobiont is probably able to synthesize most of the common amino acids and that Symbiodinium is potentially able to provide essential amino acids to its host. We believe this to be the first molecular evidence of complementarity in amino acid metabolism between coral hosts and their symbionts. We successfully assembled genes originating from both the host coral and the symbiotic Symbiodinium to create a snapshot of the coral holobiont transcriptome. This dataset will facilitate a deeper understanding of molecular mechanisms of coral symbioses and stress responses.

Variability in oceanographic barriers to coral larval dispersal: Do currents shape biodiversity?

NASA Astrophysics Data System (ADS)

Thompson, D. M.; Kleypas, J.; Castruccio, F.; Curchitser, E. N.; Pinsky, M. L.; Jönsson, B.; Watson, J. R.

2018-07-01

The global center of marine biodiversity is located in the western tropical Pacific in a region known as the "Coral Triangle" (CT). This region is also considered the most threatened of all coral reef regions, because multiple impacts, including rising temperatures and coral bleaching, have already caused high mortality of reef corals over large portions of the CT. Larval dispersal and recruitment play a critical role in reef recovery after such disturbances, but our understanding of reproductive connectivity between reefs is limited by a paucity of observations. Oceanographic modeling can provide an economical and efficient way to augment our understanding of reef connectivity, particularly over an area as large as the CT, where marine ecosystem management has become a priority. This work combines daily averaged surface current velocity and direction from a Regional Ocean Modeling System developed for the CT region (CT-ROMS) with a Lagrangian particle tracking tool (TRACMASS) to investigate the probability of larval transport between reefs for a typical broadcasting coral. A 47-year historical simulation (1960-2006) was used to analyze the potential connectivity, the physical drivers of larval transport, and its variability following bi-annual spawning events in April and September. Potential connectivity between reefs was highly variable from year to year, emphasizing the need for long simulations. The results suggest that although reefs in this region are highly self-seeded, comparatively rare long-distance dispersal events may play a vital role in shaping regional patterns of reef biodiversity and recovery following disturbance. The spatial pattern of coral "subpopulations," which are based on the potential connectivity between reefs, agrees with observed regional-scale patterns of biodiversity, suggesting that the physical barriers to larval dispersal are a first-order driver of coral biodiversity in the CT region. These physical barriers persist through the 21st Century when the model is forced with the Community Earth System Model (CESM) RCP8.5 climate scenario, despite some regional changes in connectivity between reefs.

The chemical cue tetrabromopyrrole from a biofilm bacterium induces settlement of multiple Caribbean corals

PubMed Central

Sneed, Jennifer M.; Sharp, Koty H.; Ritchie, Kimberly B.; Paul, Valerie J.

2014-01-01

Microbial biofilms induce larval settlement for some invertebrates, including corals; however, the chemical cues involved have rarely been identified. Here, we demonstrate the role of microbial biofilms in inducing larval settlement with the Caribbean coral Porites astreoides and report the first instance of a chemical cue isolated from a marine biofilm bacterium that induces complete settlement (attachment and metamorphosis) of Caribbean coral larvae. Larvae settled in response to natural biofilms, and the response was eliminated when biofilms were treated with antibiotics. A similar settlement response was elicited by monospecific biofilms of a single bacterial strain, Pseudoalteromonas sp. PS5, isolated from the surface biofilm of a crustose coralline alga. The activity of Pseudoalteromonas sp. PS5 was attributed to the production of a single compound, tetrabromopyrrole (TBP), which has been shown previously to induce metamorphosis without attachment in Pacific acroporid corals. In addition to inducing settlement of brooded larvae (P. astreoides), TBP also induced larval settlement for two broadcast-spawning species, Orbicella (formerly Montastraea) franksi and Acropora palmata, indicating that this compound may have widespread importance among Caribbean coral species. PMID:24850918

Environmental factors limiting fertilisation and larval success in corals

NASA Astrophysics Data System (ADS)

Woods, Rachael M.; Baird, Andrew H.; Mizerek, Toni L.; Madin, Joshua S.

2016-12-01

Events in the early life history of reef-building corals, including fertilisation and larval survival, are susceptible to changes in the chemical and physical properties of sea water. Quantifying how changes in water quality affect these events is therefore important for understanding and predicting population establishment in novel and changing environments. A review of the literature identified that levels of salinity, temperature, pH, suspended sediment, nutrients and heavy metals affect coral early life-history stages to various degrees. In this study, we combined published experimental data to determine the relative importance of sea water properties for coral fertilisation success and larval survivorship. Of the water properties manipulated in experiments, fertilisation success was most sensitive to suspended sediment, copper, salinity, phosphate and ammonium. Larval survivorship was sensitive to copper, lead and salinity. A combined model was developed that estimated the joint probability of both fertilisation and larval survivorship in sea water with different chemical and physical properties. We demonstrated the combined model using water samples from Sydney and Lizard Island in Australia to estimate the likelihood of larvae surviving through both stages of development to settlement competency. Our combined model could be used to recommend targets for water quality in coastal waterways as well as to predict the potential for species to expand their geographical ranges in response to climate change.

Novel transcriptome resources for three scleractinian coral species from the Indo-Pacific

PubMed Central

Kenkel, Carly D.; Bay, Line K

2017-01-01

Abstract Transcriptomic resources for coral species can provide insight into coral evolutionary history and stress-response physiology. Goniopora columna, Galaxea astreata, and Galaxea acrhelia are scleractinian corals of the Indo-Pacific, representing a diversity of morphologies and life-history traits. G. columna and G. astreata are common and cosmopolitan, while G. acrhelia is largely restricted to the coral triangle and Great Barrier Reef. Reference transcriptomes for these species were assembled from replicate colony fragments exposed to elevated (31°C) and ambient (27°C) temperatures. Trinity was used to create de novo assemblies for each species from 92–102 million raw Illumina Hiseq 2 × 150 bp reads. Host-specific assemblies contained 65 460–72 405 contigs, representing 26 693–37 894 isogroups (∼genes) with an average N50 of 2254. Gene name and/or gene ontology annotations were possible for 58% of isogroups on average. Transcriptomes contained 93.1–94.3% of EuKaryotic Orthologous Groups comprising the core eukaryotic gene set, and 89.98–91.92% of the single-copy metazoan core gene set orthologs were complete, indicating fairly comprehensive assemblies. This work expands the complement of transcriptomic resources available for scleractinian coral species, including the first reference for a representative of Goniopora spp. as well as species with novel morphology. PMID:28938722

Novel transcriptome resources for three scleractinian coral species from the Indo-Pacific.

PubMed

Kenkel, Carly D; Bay, Line K

2017-09-01

Transcriptomic resources for coral species can provide insight into coral evolutionary history and stress-response physiology. Goniopora columna, Galaxea astreata, and Galaxea acrhelia are scleractinian corals of the Indo-Pacific, representing a diversity of morphologies and life-history traits. G. columna and G. astreata are common and cosmopolitan, while G. acrhelia is largely restricted to the coral triangle and Great Barrier Reef. Reference transcriptomes for these species were assembled from replicate colony fragments exposed to elevated (31°C) and ambient (27°C) temperatures. Trinity was used to create de novo assemblies for each species from 92-102 million raw Illumina Hiseq 2 × 150 bp reads. Host-specific assemblies contained 65 460-72 405 contigs, representing 26 693-37 894 isogroups (∼genes) with an average N50 of 2254. Gene name and/or gene ontology annotations were possible for 58% of isogroups on average. Transcriptomes contained 93.1-94.3% of EuKaryotic Orthologous Groups comprising the core eukaryotic gene set, and 89.98-91.92% of the single-copy metazoan core gene set orthologs were complete, indicating fairly comprehensive assemblies. This work expands the complement of transcriptomic resources available for scleractinian coral species, including the first reference for a representative of Goniopora spp. as well as species with novel morphology. © The Authors 2017. Published by Oxford University Press.

Coral settlement onto Halimeda opuntia: a fatal attraction to an ephemeral substrate?

NASA Astrophysics Data System (ADS)

Nugues, Maggy M.; Szmant, Alina M.

2006-11-01

Degraded reefs with a high abundance of macroalgae usually also have low densities of coral recruits. Few studies, however, have examined whether these algae affect coral larval settlement. This study demonstrates, experimentally, that larvae of the Caribbean coral Favia fragrum can settle on the green alga Halimeda opuntia even when another substrate more suitable for settlement is present. Larval settlement onto experimental substrates was quantified under three treatments: rubble only, rubble plus plastic algal mimic, and rubble plus live H. opuntia. Similar total larval settlement was observed in all treatments. No larvae settled on the algal mimic, but total settlement was similar on the rubble in the first two treatments, showing that the rubble alone offered sufficient substrate for high settlement success. About half the larvae in the live algal treatment settled on H. opuntia instead of on the rubble, showing that larvae did not reject this substrate as they did the algal mimic. This result raises the possibility that corals will settle on some macroalgae when their abundance is high. Most macroalgae, including H. opuntia, are ephemeral substrates unsuitable for post-settlement survival. Such unexpected settlement may therefore have significant consequences for coral recruitment success on algal-dominated reefs.

Fish larval recruitment to reefs is a thyroid hormone-mediated metamorphosis sensitive to the pesticide chlorpyrifos

PubMed Central

Lambert, Anne; François, Loïc; Barth, Paul; Gillet, Benjamin; Hughes, Sandrine; Piganeau, Gwenaël; Leulier, Francois; Viriot, Laurent

2017-01-01

Larval recruitment, the transition of pelagic larvae into reef-associated juveniles, is a critical step for the resilience of marine fish populations but its molecular control is unknown. Here, we investigate whether thyroid-hormones (TH) and their receptors (TR) coordinate the larval recruitment of the coral-reef-fish Acanthurus triostegus. We demonstrate an increase of TH-levels and TR-expressions in pelagic-larvae, followed by a decrease in recruiting juveniles. We generalize these observations in four other coral reef-fish species. Treatments with TH or TR-antagonist, as well as relocation to the open-ocean, disturb A. triostegus larvae transformation and grazing activity. Likewise, chlorpyrifos, a pesticide often encountered in coral-reefs, impairs A. triostegus TH-levels, transformation, and grazing activity, hence diminishing this herbivore’s ability to control the spread of reef-algae. Larval recruitment therefore corresponds to a TH-controlled metamorphosis, sensitive to endocrine disruption. This provides a framework to understand how larval recruitment, critical to reef-ecosystems maintenance, is altered by anthropogenic stressors. PMID:29083300

In Silico Comparative Transcriptome Analysis of Two Color Morphs of the Common Coral Trout (Plectropomus Leopardus)

PubMed Central

Wang, Le; Yu, Cuiping; Guo, Liang; Lin, Haoran; Meng, Zining

2015-01-01

The common coral trout is one species of major importance in commercial fisheries and aquaculture. Recently, two different color morphs of Plectropomus leopardus were discovered and the biological importance of the color difference is unknown. Since coral trout species are poorly characterized at the molecular level, we undertook the transcriptomic characterization of the two color morphs, one black and one red coral trout, using Illumina next generation sequencing technologies. The study produced 55162966 and 54588952 paired-end reads, for black and red trout, respectively. De novo transcriptome assembly generated 95367 and 99424 unique sequences in black and red trout, respectively, with 88813 sequences shared between them. Approximately 50% of both trancriptomes were functionally annotated by BLAST searches against protein databases. The two trancriptomes were enriched into 25 functional categories and showed similar profiles of Gene Ontology category compositions. 34110 unigenes were grouped into 259 KEGG pathways. Moreover, we identified 14649 simple sequence repeats (SSRs) and designed primers for potential application. We also discovered 130524 putative single nucleotide polymorphisms (SNPs) in the two transcriptomes, supplying potential genomic resources for the coral trout species. In addition, we identified 936 fast-evolving genes and 165 candidate genes under positive selection between the two color morphs. Finally, 38 candidate genes underlying the mechanism of color and pigmentation were also isolated. This study presents the first transcriptome resources for the common coral trout and provides basic information for the development of genomic tools for the identification, conservation, and understanding of the speciation and local adaptation of coral reef fish species. PMID:26713756

Induction of Larval Metamorphosis of the Coral Acropora millepora by Tetrabromopyrrole Isolated from a Pseudoalteromonas Bacterium

PubMed Central

Tebben, Jan; Tapiolas, Dianne M.; Motti, Cherie A.; Abrego, David; Negri, Andrew P.; Blackall, Linda L.; Steinberg, Peter D.; Harder, Tilmann

2011-01-01

The induction of larval attachment and metamorphosis of benthic marine invertebrates is widely considered to rely on habitat specific cues. While microbial biofilms on marine hard substrates have received considerable attention as specific signals for a wide and phylogenetically diverse array of marine invertebrates, the presumed chemical settlement signals produced by the bacteria have to date not been characterized. Here we isolated and fully characterized the first chemical signal from bacteria that induced larval metamorphosis of acroporid coral larvae (Acropora millepora). The metamorphic cue was identified as tetrabromopyrrole (TBP) in four bacterial Pseudoalteromonas strains among a culture library of 225 isolates obtained from the crustose coralline algae Neogoniolithon fosliei and Hydrolithon onkodes. Coral planulae transformed into fully developed polyps within 6 h, but only a small proportion of these polyps attached to the substratum. The biofilm cell density of the four bacterial strains had no influence on the ratio of attached vs. non-attached polyps. Larval bioassays with ethanolic extracts of the bacterial isolates, as well as synthetic TBP resulted in consistent responses of coral planulae to various doses of TBP. The lowest bacterial density of one of the Pseudoalteromonas strains which induced metamorphosis was 7,000 cells mm−2 in laboratory assays, which is on the order of 0.1 –1% of the total numbers of bacteria typically found on such surfaces. These results, in which an actual cue from bacteria has been characterized for the first time, contribute significantly towards understanding the complex process of acroporid coral larval settlement mediated through epibiotic microbial biofilms on crustose coralline algae. PMID:21559509

Effects of coal contamination on early life history processes of a reef-building coral, Acropora tenuis.

PubMed

Berry, Kathryn L E; Hoogenboom, Mia O; Brinkman, Diane L; Burns, Kathryn A; Negri, Andrew P

2017-01-15

Successful reproduction and larval dispersal are important for the persistence of marine invertebrate populations, and these early life history processes can be sensitive to marine pollution. Coal is emerging as a contaminant of interest due to the proximity of ports and shipping lanes to coral reefs. To assess the potential hazard of this contaminant, gametes, newly developed embryos, larvae and juveniles of the coral Acropora tenuis were exposed to a range of coal leachate, suspended coal, and coal smothering treatments. Fertilisation was the most sensitive reproductive process tested. Embryo survivorship decreased with increasing suspended coal concentrations and exposure duration, effects on larval settlement varied between treatments, while effects on juvenile survivorship were minimal. Leachate exposures had negligible effects on fertilisation and larval settlement. These results indicate that coral recruitment could be affected by spills that produce plumes of suspended coal particles which interact with gametes and embryos soon after spawning. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Impacts of Larval Connectivity on Coral Heat Tolerance

NASA Astrophysics Data System (ADS)

Pinsky, M. L.; Kleypas, J. A.; Thompson, D. M.; Castruccio, F. S.; Curchitser, E. N.; Watson, J. R.

2016-02-01

The sensitivity of corals to elevated temperature depends on their acclimation and adaptation to the local maximum temperature regime. Through larval dispersal, however, coral populations can receive larvae from regions that are significantly warmer or colder. If these exogenous larvae carry genetic-based tolerances to colder or warmer temperatures, then the thermal sensitivity of the receiving population may be lower or higher, respectively. Using a high-resolution Regional Ocean Modeling System (ROMS) configuration for the Coral Triangle region, we quantify the potential role of connectivity in determining the thermal stress threshold (TST) of a typical broadcast spawner. The model results suggest that even with a pelagic larval dispersal period of only 10 days, many reefs receive larvae from reefs that are warmer or cooler than the local temperature, and that accounting for this connectivity improves bleaching predictions. This has important implications for conservation planning, because connectivity may allow some reefs to have an inherited heat tolerance that is higher or lower than would be predicted based on local conditions alone.

Larval settlement preferences and post-settlement survival of the threatened Caribbean corals Acropora palmata and A. cervicornis

NASA Astrophysics Data System (ADS)

Ritson-Williams, R.; Paul, Valerie J.; Arnold, S. N.; Steneck, R. S.

2010-03-01

The settlement specificity of two threatened Caribbean corals, Acropora palmata and A. cervicornis, was tested by measuring their rates of larval metamorphosis in response to crustose coralline algae (CCA) and other substrata. In the no-choice experiments, the coral larvae were placed in six treatments: filtered seawater (FSW), a fragment of biofilmed dead skeleton of A. palmata, or a fragment of one of four species of CCA ( Hydrolithon boergesenii, Porolithon pachydermum, Paragoniolithon solubile, and Titanoderma prototypum). Within each CCA treatment, there were three different substrata on which to settle and metamorphose: (1) the CCA surface, (2) the rock under the CCA, or (3) the plastic dish. The 5-day-old larvae of both A. palmata and A. cervicornis had similar rates of total metamorphosis (all substrata combined) in every treatment (excluding FSW) even in the absence of CCA. However, there were differences in larval behavior among the CCA species since the larvae settled and metamorphosed on different substrata in the presence of different CCA species. In the no-choice experiments the larvae of both corals had higher rates of metamorphosis on the top surfaces of H. boergesenii and/or T. prototypum than on P. pachydermum. In the choice experiments, the coral larvae were offered two species of CCA in the same dish. When given a choice, both species of coral larvae had more settlement and metamorphosis on the surface of H. boergesenii or T. prototypum or clean rock than onto the surface of P. solubile. After 6 weeks in the field, transplanted A. palmata recruits had approximately 15% survival on both T. prototypum and H. boergesenii, but A. cervicornis recruits only survived on T. prototypum (13%). Some, but not all, CCA species facilitated the larval settlement and post-settlement survival of these two threatened corals, highlighting the importance of benthic community composition for successful coral recruitment.

Transcriptomes and expression profiling of deep-sea corals from the Red Sea provide insight into the biology of azooxanthellate corals.

PubMed

Yum, Lauren K; Baumgarten, Sebastian; Röthig, Till; Roder, Cornelia; Roik, Anna; Michell, Craig; Voolstra, Christian R

2017-07-25

Despite the importance of deep-sea corals, our current understanding of their ecology and evolution is limited due to difficulties in sampling and studying deep-sea environments. Moreover, a recent re-evaluation of habitat limitations has been suggested after characterization of deep-sea corals in the Red Sea, where they live at temperatures of above 20 °C at low oxygen concentrations. To gain further insight into the biology of deep-sea corals, we produced reference transcriptomes and studied gene expression of three deep-sea coral species from the Red Sea, i.e. Dendrophyllia sp., Eguchipsammia fistula, and Rhizotrochus typus. Our analyses suggest that deep-sea coral employ mitochondrial hypometabolism and anaerobic glycolysis to manage low oxygen conditions present in the Red Sea. Notably, we found expression of genes related to surface cilia motion that presumably enhance small particle transport rates in the oligotrophic deep-sea environment. This is the first study to characterize transcriptomes and in situ gene expression for deep-sea corals. Our work offers several mechanisms by which deep-sea corals might cope with the distinct environmental conditions present in the Red Sea As such, our data provide direction for future research and further insight to organismal response of deep-sea coral to environmental change and ocean warming.

Coral thermal tolerance: tuning gene expression to resist thermal stress.

PubMed

Bellantuono, Anthony J; Granados-Cifuentes, Camila; Miller, David J; Hoegh-Guldberg, Ove; Rodriguez-Lanetty, Mauricio

2012-01-01

The acclimatization capacity of corals is a critical consideration in the persistence of coral reefs under stresses imposed by global climate change. The stress history of corals plays a role in subsequent response to heat stress, but the transcriptomic changes associated with these plastic changes have not been previously explored. In order to identify host transcriptomic changes associated with acquired thermal tolerance in the scleractinian coral Acropora millepora, corals preconditioned to a sub-lethal temperature of 3°C below bleaching threshold temperature were compared to both non-preconditioned corals and untreated controls using a cDNA microarray platform. After eight days of hyperthermal challenge, conditions under which non-preconditioned corals bleached and preconditioned corals (thermal-tolerant) maintained Symbiodinium density, a clear differentiation in the transcriptional profiles was revealed among the condition examined. Among these changes, nine differentially expressed genes separated preconditioned corals from non-preconditioned corals, with 42 genes differentially expressed between control and preconditioned treatments, and 70 genes between non-preconditioned corals and controls. Differentially expressed genes included components of an apoptotic signaling cascade, which suggest the inhibition of apoptosis in preconditioned corals. Additionally, lectins and genes involved in response to oxidative stress were also detected. One dominant pattern was the apparent tuning of gene expression observed between preconditioned and non-preconditioned treatments; that is, differences in expression magnitude were more apparent than differences in the identity of genes differentially expressed. Our work revealed a transcriptomic signature underlying the tolerance associated with coral thermal history, and suggests that understanding the molecular mechanisms behind physiological acclimatization would be critical for the modeling of reefs in impending climate change scenarios.

Coral Thermal Tolerance: Tuning Gene Expression to Resist Thermal Stress

PubMed Central

Bellantuono, Anthony J.; Granados-Cifuentes, Camila; Miller, David J.; Hoegh-Guldberg, Ove; Rodriguez-Lanetty, Mauricio

2012-01-01

The acclimatization capacity of corals is a critical consideration in the persistence of coral reefs under stresses imposed by global climate change. The stress history of corals plays a role in subsequent response to heat stress, but the transcriptomic changes associated with these plastic changes have not been previously explored. In order to identify host transcriptomic changes associated with acquired thermal tolerance in the scleractinian coral Acropora millepora, corals preconditioned to a sub-lethal temperature of 3°C below bleaching threshold temperature were compared to both non-preconditioned corals and untreated controls using a cDNA microarray platform. After eight days of hyperthermal challenge, conditions under which non-preconditioned corals bleached and preconditioned corals (thermal-tolerant) maintained Symbiodinium density, a clear differentiation in the transcriptional profiles was revealed among the condition examined. Among these changes, nine differentially expressed genes separated preconditioned corals from non-preconditioned corals, with 42 genes differentially expressed between control and preconditioned treatments, and 70 genes between non-preconditioned corals and controls. Differentially expressed genes included components of an apoptotic signaling cascade, which suggest the inhibition of apoptosis in preconditioned corals. Additionally, lectins and genes involved in response to oxidative stress were also detected. One dominant pattern was the apparent tuning of gene expression observed between preconditioned and non-preconditioned treatments; that is, differences in expression magnitude were more apparent than differences in the identity of genes differentially expressed. Our work revealed a transcriptomic signature underlying the tolerance associated with coral thermal history, and suggests that understanding the molecular mechanisms behind physiological acclimatization would be critical for the modeling of reefs in impending climate change scenarios. PMID:23226355

The Role of Maternal Nutrition on Oocyte Size and Quality, with Respect to Early Larval Development in The Coral-Eating Starfish, Acanthaster planci.

PubMed

Caballes, Ciemon Frank; Pratchett, Morgan S; Kerr, Alexander M; Rivera-Posada, Jairo A

2016-01-01

Variation in local environmental conditions can have pronounced effects on the population structure and dynamics of marine organisms. Previous studies on crown-of-thorns starfish, Acanthaster planci, have primarily focused on effects of water quality and nutrient availability on larval growth and survival, while the role of maternal nutrition on reproduction and larval development has been overlooked. To examine the effects of maternal nutrition on oocyte size and early larval development in A. planci, we pre-conditioned females for 60 days on alternative diets of preferred coral prey (Acropora abrotanoides) versus non-preferred coral prey (Porites rus) and compared resulting gametes and progeny to those produced by females that were starved over the same period. Females fed ad libitum with Acropora increased in weight, produced heavier gonads and produced larger oocytes compared to Porites-fed and starved females. Fed starfish (regardless of whether it was Acropora or Porites) produced bigger larvae with larger stomachs and had a higher frequency of normal larvae that reached the late bipinnaria / early brachiolaria stage compared to starved starfish. Females on Acropora diet also produced a higher proportion of larvae that progressed to more advanced stages faster compared to Porites-fed starfish, which progressed faster than starved starfish. These results suggest that maternal provisioning can have important consequences for the quality and quantity of progeny. Because food quality (coral community structure) and quantity (coral abundance) varies widely among reef locations and habitats, local variation in maternal nutrition of A. planci is likely to moderate reproductive success and may explain temporal and spatial fluctuations in abundance of this species.

The Role of Maternal Nutrition on Oocyte Size and Quality, with Respect to Early Larval Development in The Coral-Eating Starfish, Acanthaster planci

PubMed Central

Pratchett, Morgan S.; Kerr, Alexander M.; Rivera-Posada, Jairo A.

2016-01-01

Variation in local environmental conditions can have pronounced effects on the population structure and dynamics of marine organisms. Previous studies on crown-of-thorns starfish, Acanthaster planci, have primarily focused on effects of water quality and nutrient availability on larval growth and survival, while the role of maternal nutrition on reproduction and larval development has been overlooked. To examine the effects of maternal nutrition on oocyte size and early larval development in A. planci, we pre-conditioned females for 60 days on alternative diets of preferred coral prey (Acropora abrotanoides) versus non-preferred coral prey (Porites rus) and compared resulting gametes and progeny to those produced by females that were starved over the same period. Females fed ad libitum with Acropora increased in weight, produced heavier gonads and produced larger oocytes compared to Porites-fed and starved females. Fed starfish (regardless of whether it was Acropora or Porites) produced bigger larvae with larger stomachs and had a higher frequency of normal larvae that reached the late bipinnaria / early brachiolaria stage compared to starved starfish. Females on Acropora diet also produced a higher proportion of larvae that progressed to more advanced stages faster compared to Porites-fed starfish, which progressed faster than starved starfish. These results suggest that maternal provisioning can have important consequences for the quality and quantity of progeny. Because food quality (coral community structure) and quantity (coral abundance) varies widely among reef locations and habitats, local variation in maternal nutrition of A. planci is likely to moderate reproductive success and may explain temporal and spatial fluctuations in abundance of this species. PMID:27327627

Differential larval settlement responses of Porites astreoides and Acropora palmata in the presence of the green alga Halimeda opuntia

NASA Astrophysics Data System (ADS)

Olsen, K.; Sneed, J. M.; Paul, V. J.

2016-06-01

Settlement is critical to maintaining coral cover on reefs, yet interspecific responses of coral planulae to common benthic macroalgae are not well characterized. Larval survival and settlement of two Caribbean reef-building corals, the broadcast-spawner Acropora palmata and the planulae-brooder Porites astreoides, were quantified following exposure to plastic algae controls and the green macroalga Halimeda opuntia. Survival and settlement rates were not significantly affected by the presence of H. opuntia in either species. However, ~10 % of P. astreoides larvae settled on the surface of the macroalga, whereas larvae of A. palmata did not. It is unlikely that corals that settle on macroalgae will survive post-settlement; therefore, H. opuntia may reduce the number of P. astreoides and other non-discriminatory larvae that survive to adulthood. Our results suggest that the presence of macroalgae on impacted reefs can have unexpected repercussions for coral recruitment and highlight discrepancies in settlement specificity between corals with distinct life history strategies.

A Possible Role for Vitamin C in Coral Calcification

NASA Astrophysics Data System (ADS)

Rosenthal, J. J.; Roberson, L.; Vazquez, N.

2016-02-01

Despite the importance of coral reefs to tropical, marine ecosystems, the biological components of the calcification process are poorly understood. Because calcification must involve the delivery of organic and inorganic components across cell membranes, we postulate that it has similar features to epithelial and neuronal transport mechanisms in vertebrates. Accordingly, we are interested in identifying the specific membrane transporters underlying skeleton formation. As a model, we are using larvae from the ubiquitous Caribbean species Porites astreoides, a rapidly growing stony coral that is resistant to anthropogenic stressors. Using Illumina RNAseq, we assembled a larval transcriptome and compared gene expression between swimming larvae and recently settled ones that had just commenced the process of calcification. As expected, we identified many ion transporter, pump and channel transcripts that were upregulated in settled larvae. It was surprising, however, to find that the most upregulated transcript appeared to encode a Na-dependent Vitamin C transporter (SLC23A). In vertebrates, SLC23A transporters play a vital role in bone morphogenesis where Vitamin C is an essential cofactor for enzymes that condition collagen precursors for assembly into mature molecules. In corals, collagen has been identified as a component of the skeleton's extracellular matrix. Using in situ hybridization, we showed that the P. astreoides SLC23A messages were expressed in regions adjacent to rapid skeleton formation, on the aboral surface and septa of settled larvae. To confirm that the coral clone is indeed a Vitamin C transporter, we expressed it in Xenopus oocytes and studied its activity using voltage-clamp. Preliminary data demonstrate that it induces a current that is activated by Na and Vitamin C. This approach will help us better understand the molecular mechanisms underlying calcification and how they might respond to environmental change.

Whole transcriptome analysis reveals changes in expression of immune-related genes during and after bleaching in a reef-building coral.

PubMed

Pinzón, Jorge H; Kamel, Bishoy; Burge, Colleen A; Harvell, C Drew; Medina, Mónica; Weil, Ernesto; Mydlarz, Laura D

2015-04-01

Climate change is negatively affecting the stability of natural ecosystems, especially coral reefs. The dissociation of the symbiosis between reef-building corals and their algal symbiont, or coral bleaching, has been linked to increased sea surface temperatures. Coral bleaching has significant impacts on corals, including an increase in disease outbreaks that can permanently change the entire reef ecosystem. Yet, little is known about the impacts of coral bleaching on the coral immune system. In this study, whole transcriptome analysis of the coral holobiont and each of the associate components (i.e. coral host, algal symbiont and other associated microorganisms) was used to determine changes in gene expression in corals affected by a natural bleaching event as well as during the recovery phase. The main findings include evidence that the coral holobiont and the coral host have different responses to bleaching, and the host immune system appears suppressed even a year after a bleaching event. These results support the hypothesis that coral bleaching changes the expression of innate immune genes of corals, and these effects can last even after recovery of symbiont populations. Research on the role of immunity on coral's resistance to stressors can help make informed predictions on the future of corals and coral reefs.

Whole transcriptome analysis reveals changes in expression of immune-related genes during and after bleaching in a reef-building coral

PubMed Central

Pinzón, Jorge H.; Kamel, Bishoy; Burge, Colleen A.; Harvell, C. Drew; Medina, Mónica; Weil, Ernesto; Mydlarz, Laura D.

2015-01-01

Climate change is negatively affecting the stability of natural ecosystems, especially coral reefs. The dissociation of the symbiosis between reef-building corals and their algal symbiont, or coral bleaching, has been linked to increased sea surface temperatures. Coral bleaching has significant impacts on corals, including an increase in disease outbreaks that can permanently change the entire reef ecosystem. Yet, little is known about the impacts of coral bleaching on the coral immune system. In this study, whole transcriptome analysis of the coral holobiont and each of the associate components (i.e. coral host, algal symbiont and other associated microorganisms) was used to determine changes in gene expression in corals affected by a natural bleaching event as well as during the recovery phase. The main findings include evidence that the coral holobiont and the coral host have different responses to bleaching, and the host immune system appears suppressed even a year after a bleaching event. These results support the hypothesis that coral bleaching changes the expression of innate immune genes of corals, and these effects can last even after recovery of symbiont populations. Research on the role of immunity on coral's resistance to stressors can help make informed predictions on the future of corals and coral reefs. PMID:26064625

Variability in reef connectivity in the Coral Triangle

NASA Astrophysics Data System (ADS)

Thompson, D. M.; Kleypas, J. A.; Castruccio, F. S.; Watson, J. R.; Curchitser, E. N.

2015-12-01

The Coral Triangle (CT) is not only the global center of marine biodiversity, it also supports the livelihoods of millions of people. Unfortunately, it is also considered the most threatened of all reef regions, with rising temperature and coral bleaching already taking a toll. Reproductive connectivity between reefs plays a critical role in the reef's capacity to recover after such disturbances. Thus, oceanographic modeling efforts to understand patterns of reef connectivity are essential to the effective design of a network of Marine Protected Areas (MPAs) to conserve marine ecosystems in the Coral Triangle. Here, we combine a Regional Ocean Modeling System developed for the Coral Triangle (CT-ROMS) with a Lagrangian particle tracking tool (TRACMASS) to investigate the probability of coral larval transport between reefs. A 47-year hindcast simulation (1960-2006) was used to investigate the variability in larval transport of a broadcasting coral following mass spawning events in April and September. Potential connectivity between reefs was highly variable and stochastic from year to year, emphasizing the importance of decadal or longer simulations in identifying connectivity patterns, key source and sink regions, and thus marine management targets for MPAs. The influence of temperature on realized connectivity (future work) may add further uncertainty to year-to-year patterns of connectivity between reefs. Nonetheless, the potential connectivity results we present here suggest that although reefs in this region are primarily self-seeded, rare long-distance dispersal may promote recovery and genetic exchange between reefs in the region. The spatial pattern of "subpopulations" based solely on the physical drivers of connectivity between reefs closely match regional patterns of biodiversity, suggesting that physical barriers to larval dispersal may be a key driver of reef biodiversity. Finally, 21st Century simulations driven by the Community Earth System Model (CESM) suggest that these major barriers to larval dispersal persist into the future under 8.5 W/m2 of climate forcing, despite some regional changes in connectivity between reefs.

Local replenishment of coral reef fish populations in a marine reserve.

PubMed

Almany, Glenn R; Berumen, Michael L; Thorrold, Simon R; Planes, Serge; Jones, Geoffrey P

2007-05-04

The scale of larval dispersal of marine organisms is important for the design of networks of marine protected areas. We examined the fate of coral reef fish larvae produced at a small island reserve, using a mass-marking method based on maternal transmission of stable isotopes to offspring. Approximately 60% of settled juveniles were spawned at the island, for species with both short (<2 weeks) and long (>1 month) pelagic larval durations. If natal homing of larvae is a common life-history strategy, the appropriate spatial scales for the management and conservation of coral reefs are likely to be much smaller than previously assumed.

A comparative view of early development in the corals Favia lizardensis, Ctenactis echinata, and Acropora millepora - morphology, transcriptome, and developmental gene expression.

PubMed

Okubo, Nami; Hayward, David C; Forêt, Sylvain; Ball, Eldon E

2016-02-29

Research into various aspects of coral biology has greatly increased in recent years due to anthropogenic threats to coral health including pollution, ocean warming and acidification. However, knowledge of coral early development has lagged. The present paper describes the embryonic development of two previously uncharacterized robust corals, Favia lizardensis (a massive brain coral) and Ctenactis echinata (a solitary coral) and compares it to that of the previously characterized complex coral, Acropora millepora, both morphologically and in terms of the expression of a set of key developmental genes. Illumina sequencing of mixed age embryos was carried out, resulting in embryonic transcriptomes consisting of 40605 contigs for C.echinata (N50 = 1080 bp) and 48536 contigs for F.lizardensis (N50 = 1496 bp). The transcriptomes have been annotated against Swiss-Prot and were sufficiently complete to enable the identification of orthologs of many key genes controlling development in bilaterians. Developmental series of images of whole mounts and sections reveal that the early stages of both species contain a blastocoel, consistent with their membership of the robust clade. In situ hybridization was used to examine the expression of the developmentally important genes brachyury, chordin and forkhead. The expression of brachyury and forkhead was consistent with that previously reported for Acropora and allowed us to confirm that the pseudo-blastopore sometimes seen in robust corals such as Favia spp. is not directly associated with gastrulation. C.echinata chordin expression, however, differed from that seen in the other two corals. Embryonic transcriptomes were assembled for the brain coral Favia lizardensis and the solitary coral Ctenactis echinata. Both species have a blastocoel in their early developmental stages, consistent with their phylogenetic position as members of the robust clade. Expression of the key developmental genes brachyury, chordin and forkhead was investigated, allowing comparison to that of their orthologs in Acropora, Nematostella and bilaterians and demonstrating that even within the Anthozoa there are significant differences in expression patterns.

Fertile fathoms: Deep reproductive refugia for threatened shallow corals

PubMed Central

Holstein, Daniel M.; Smith, Tyler B.; Gyory, Joanna; Paris, Claire B.

2015-01-01

The persistence of natural metapopulations may depend on subpopulations that exist at the edges of species ranges, removed from anthropogenic stress. Mesophotic coral ecosystems (30–150 m) are buffered from disturbance by depth and distance, and are potentially massive reservoirs of coral diversity and fecundity; yet we know little about the reproductive capabilities of their constituent species and the potential for these marginal environments to influence patterns of coral reef persistence. We investigated the reproductive performance of the threatened depth-generalist coral Orbicella faveolata over the extent of its vertical range to assess mesophotic contributions to regional larval pools. Over equal habitat area, mesophotic coral populations were found to produce over an order of magnitude more eggs than nearby shallow populations. Positive changes with depth in both population abundance and polyp fecundity contributed to this discrepancy. Relative larval pool contributions of deeper living corals will likely increase as shallow habitats further degrade due to climate change and local habitat degradation. This is a compelling example of the potential for marginal habitat to be critical to metapopulation persistence as reproductive refugia. PMID:26196243

The role of transcriptome resilience in resistance of corals to bleaching.

PubMed

Seneca, Francois O; Palumbi, Stephen R

2015-04-01

Wild populations increasingly experience extreme conditions as climate change amplifies environmental variability. How individuals respond to environmental extremes determines the impact of climate change overall. The variability of response from individual to individual can represent the opportunity for natural selection to occur as a result of extreme conditions. Here, we experimentally replicated the natural exposure to extreme temperatures of the reef lagoon at Ofu Island (American Samoa), where corals can experience severe heat stress during midday low tide. We investigated the bleaching and transcriptome response of 20 Acropora hyacinthus colonies 5 and 20 h after exposure to control (29 °C) or heated (35 °C) conditions. We found a highly dynamic transcriptome response: 27% of the coral transcriptome was significantly regulated 1 h postheat exposure. Yet 15 h later, when heat-induced coral bleaching became apparent, only 12% of the transcriptome was differentially regulated. A large proportion of responsive genes at the first time point returned to control levels, others remained differentially expressed over time, while an entirely different subset of genes was successively regulated at the second time point. However, a noteworthy variability in gene expression was observed among individual coral colonies. Among the genes of which expression lingered over time, fast return to normal levels was associated with low bleaching. Colonies that maintained higher expression levels of these genes bleached severely. Return to normal levels of gene expression after stress has been termed transcriptome resilience, and in the case of some specific genes may signal the physiological health and response ability of individuals to environmental stress. © 2015 John Wiley & Sons Ltd.

Cumulative effects of suspended sediments, organic nutrients and temperature stress on early life history stages of the coral Acropora tenuis.

PubMed

Humanes, Adriana; Ricardo, Gerard F; Willis, Bette L; Fabricius, Katharina E; Negri, Andrew P

2017-03-10

Coral reproduction is vulnerable to both declining water quality and warming temperatures, with simultaneous exposures likely compounding the negative impact of each stressor. We investigated how early life processes of the coral Acropora tenuis respond to increasing levels of suspended sediments in combination with temperature or organic nutrients. Fertilization success and embryo development were more sensitive to suspended sediments than to high temperatures or nutrient enrichment, while larval development (after acquisition of cilia) and settlement success were predominantly affected by thermal stress. Fertilization success was reduced 80% by suspended sediments, and up to 24% by temperature, while the addition of nutrients to suspended sediments had no further impact. Larval survivorship was unaffected by any of these treatments. However, settlement success of larvae developing from treatment-exposed embryos was negatively affected by all three stressors (e.g. up to 55% by suspended sediments), while exposure only during later larval stages predominantly responded to temperature stress. Environmentally relevant levels of suspended sediments and temperature had the greatest impacts, affecting more processes than the combined impacts of sediments and nutrients. These results suggest that management strategies to maintain suspended sediments at low concentrations during coral spawning events will benefit coral recruitment, especially with warming climate.

Cumulative effects of suspended sediments, organic nutrients and temperature stress on early life history stages of the coral Acropora tenuis

NASA Astrophysics Data System (ADS)

Humanes, Adriana; Ricardo, Gerard F.; Willis, Bette L.; Fabricius, Katharina E.; Negri, Andrew P.

2017-03-01

Coral reproduction is vulnerable to both declining water quality and warming temperatures, with simultaneous exposures likely compounding the negative impact of each stressor. We investigated how early life processes of the coral Acropora tenuis respond to increasing levels of suspended sediments in combination with temperature or organic nutrients. Fertilization success and embryo development were more sensitive to suspended sediments than to high temperatures or nutrient enrichment, while larval development (after acquisition of cilia) and settlement success were predominantly affected by thermal stress. Fertilization success was reduced 80% by suspended sediments, and up to 24% by temperature, while the addition of nutrients to suspended sediments had no further impact. Larval survivorship was unaffected by any of these treatments. However, settlement success of larvae developing from treatment-exposed embryos was negatively affected by all three stressors (e.g. up to 55% by suspended sediments), while exposure only during later larval stages predominantly responded to temperature stress. Environmentally relevant levels of suspended sediments and temperature had the greatest impacts, affecting more processes than the combined impacts of sediments and nutrients. These results suggest that management strategies to maintain suspended sediments at low concentrations during coral spawning events will benefit coral recruitment, especially with warming climate.

Compartment-specific transcriptomics in a reef-building coral exposed to elevated temperatures

PubMed Central

Mayfield, Anderson B; Wang, Yu-Bin; Chen, Chii-Shiarng; Lin, Chung-Yen; Chen, Shu-Hwa

2014-01-01

Although rising ocean temperatures threaten scleractinian corals and the reefs they construct, certain reef corals can acclimate to elevated temperatures to which they are rarely exposed in situ. Specimens of the model Indo-Pacific reef coral Pocillopora damicornis collected from upwelling reefs of Southern Taiwan were previously found to have survived a 36-week exposure to 30°C, a temperature they encounter infrequently and one that can elicit the breakdown of the coral–dinoflagellate (genus Symbiodinium) endosymbiosis in many corals of the Pacific Ocean. To gain insight into the subcellular pathways utilized by both the coral hosts and their mutualistic Symbiodinium populations to acclimate to this temperature, mRNAs from both control (27°C) and high (30°C)-temperature samples were sequenced on an Illumina platform and assembled into a 236 435-contig transcriptome. These P. damicornis specimens were found to be ∼60% anthozoan and 40% microbe (Symbiodinium, other eukaryotic microbes, and bacteria), from an mRNA-perspective. Furthermore, a significantly higher proportion of genes from the Symbiodinium compartment were differentially expressed after two weeks of exposure. Specifically, at elevated temperatures, Symbiodinium populations residing within the coral gastrodermal tissues were more likely to up-regulate the expression of genes encoding proteins involved in metabolism than their coral hosts. Collectively, these transcriptome-scale data suggest that the two members of this endosymbiosis have distinct strategies for acclimating to elevated temperatures that are expected to characterize many of Earth's coral reefs in the coming decades. PMID:25354956

Compartment-specific transcriptomics in a reef-building coral exposed to elevated temperatures.

PubMed

Mayfield, Anderson B; Wang, Yu-Bin; Chen, Chii-Shiarng; Lin, Chung-Yen; Chen, Shu-Hwa

2014-12-01

Although rising ocean temperatures threaten scleractinian corals and the reefs they construct, certain reef corals can acclimate to elevated temperatures to which they are rarely exposed in situ. Specimens of the model Indo-Pacific reef coral Pocillopora damicornis collected from upwelling reefs of Southern Taiwan were previously found to have survived a 36-week exposure to 30°C, a temperature they encounter infrequently and one that can elicit the breakdown of the coral-dinoflagellate (genus Symbiodinium) endosymbiosis in many corals of the Pacific Ocean. To gain insight into the subcellular pathways utilized by both the coral hosts and their mutualistic Symbiodinium populations to acclimate to this temperature, mRNAs from both control (27°C) and high (30°C)-temperature samples were sequenced on an Illumina platform and assembled into a 236 435-contig transcriptome. These P. damicornis specimens were found to be ~60% anthozoan and 40% microbe (Symbiodinium, other eukaryotic microbes, and bacteria), from an mRNA-perspective. Furthermore, a significantly higher proportion of genes from the Symbiodinium compartment were differentially expressed after two weeks of exposure. Specifically, at elevated temperatures, Symbiodinium populations residing within the coral gastrodermal tissues were more likely to up-regulate the expression of genes encoding proteins involved in metabolism than their coral hosts. Collectively, these transcriptome-scale data suggest that the two members of this endosymbiosis have distinct strategies for acclimating to elevated temperatures that are expected to characterize many of Earth's coral reefs in the coming decades. © 2014 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

Predicting Coral Recruitment in Palau’s Complex Reef Archipelago

PubMed Central

Golbuu, Yimnang; Wolanski, Eric; Idechong, Jacques Wasai; Victor, Steven; Isechal, Adelle Lukes; Oldiais, Noelle Wenty; Idip, David; Richmond, Robert H.; van Woesik, Robert

2012-01-01

Reproduction and recruitment are key processes that replenish marine populations. Here we use the Palau archipelago, in the western Pacific Ocean, as a case study to examine scales of connectivity and to determine whether an oceanographic model, incorporating the complex reef architecture, is a useful predictor of coral recruitment. We tested the hypothesis that the reefs with the highest retention also had the highest densities of juvenile coral density from 80 field sites. Field comparisons showed a significant correlation between the densities of juvenile Acropora colonies and total larval recruitment derived from the model (i.e., calculated as the sum of the densities of larvae that self-seeded and recruited from the other reefs in the archipelago). Long-distance larval imports may be too infrequent to sustain coral populations, but are critical for recovery in times of extreme local stress. PMID:23209842

Long-distance transport of a West Atlantic stony coral on a plastic raft.

PubMed

Hoeksema, Bert W; Pedoja, Kevin; Poprawski, Yohann

2018-05-30

The occurrence of wide-spread coral species around isolated reefs and over long stretches of deep ocean cannot be explained by larval dispersal alone; their larval stage is too short for that, especially in brooding species (Nunes et al. 2011, de Souza et al. 2017). Rafting on natural substrates, such as volcanic pumice fragments, wooden logs and coconut shells has been recognized as an alternative means for transport in reef corals (Fielden 1893, Crossland 1952, Jokiel 1984). Fouling on ship hulls and oil platforms is a relatively new, anthropogenic way for coral migration and because it is fast, it escalates the risk of alien species introductions (Creed et al. 2017). This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Quantitative species-level ecology of reef fish larvae via metabarcoding.

PubMed

Kimmerling, Naama; Zuqert, Omer; Amitai, Gil; Gurevich, Tamara; Armoza-Zvuloni, Rachel; Kolesnikov, Irina; Berenshtein, Igal; Melamed, Sarah; Gilad, Shlomit; Benjamin, Sima; Rivlin, Asaph; Ohavia, Moti; Paris, Claire B; Holzman, Roi; Kiflawi, Moshe; Sorek, Rotem

2018-02-01

The larval pool of coral reef fish has a crucial role in the dynamics of adult fish populations. However, large-scale species-level monitoring of species-rich larval pools has been technically impractical. Here, we use high-throughput metabarcoding to study larval ecology in the Gulf of Aqaba, a region that is inhabited by >500 reef fish species. We analysed 9,933 larvae from 383 samples that were stratified over sites, depth and time. Metagenomic DNA extracted from pooled larvae was matched to a mitochondrial cytochrome c oxidase subunit I barcode database compiled for 77% of known fish species within this region. This yielded species-level reconstruction of the larval community, allowing robust estimation of larval spatio-temporal distributions. We found significant correlations between species abundance in the larval pool and in local adult assemblages, suggesting a major role for larval supply in determining local adult densities. We documented larval flux of species whose adults were never documented in the region, suggesting environmental filtering as the reason for the absence of these species. Larvae of several deep-sea fishes were found in shallow waters, supporting their dispersal over shallow bathymetries, potentially allowing Lessepsian migration into the Mediterranean Sea. Our method is applicable to any larval community and could assist coral reef conservation and fishery management efforts.

Embryogenesis and Larval Biology of the Cold-Water Coral Lophelia pertusa

PubMed Central

Strömberg, Susanna M.; Dahl, Mikael P.; Lundälv, Tomas; Brooke, Sandra

2014-01-01

Cold-water coral reefs form spectacular and highly diverse ecosystems in the deep sea but little is known about reproduction, and virtually nothing about the larval biology in these corals. This study is based on data from two locations of the North East Atlantic and documents the first observations of embryogenesis and larval development in Lophelia pertusa, the most common framework-building cold-water scleractinian. Embryos developed in a more or less organized radial cleavage pattern from ∼160 µm large neutral or negatively buoyant eggs, to 120–270 µm long ciliated planulae. Embryogenesis was slow with cleavage occurring at intervals of 6–8 hours up to the 64-cell stage. Genetically characterized larvae were sexually derived, with maternal and paternal alleles present. Larvae were active swimmers (0.5 mm s−1) initially residing in the upper part of the water column, with bottom probing behavior starting 3–5 weeks after fertilization. Nematocysts had developed by day 30, coinciding with peak bottom-probing behavior, and possibly an indication that larvae are fully competent to settle at this time. Planulae survived for eight weeks under laboratory conditions, and preliminary results indicate that these planulae are planktotrophic. The late onset of competency and larval longevity suggests a high dispersal potential. Understanding larval biology and behavior is of paramount importance for biophysical modeling of larval dispersal, which forms the basis for predictions of connectivity among populations. PMID:25028936

Discovery of SCORs: Anciently derived, highly conserved gene-associated repeats in stony corals.

PubMed

Qiu, Huan; Zelzion, Ehud; Putnam, Hollie M; Gates, Ruth D; Wagner, Nicole E; Adams, Diane K; Bhattacharya, Debashish

2017-10-01

Stony coral (Scleractinia) genomes are still poorly explored and many questions remain about their evolution and contribution to the success and longevity of reefs. We analyzed transcriptome and genome data from Montipora capitata, Acropora digitifera, and transcriptome data from 20 other coral species. To our surprise, we found highly conserved, anciently derived, Scleractinia COral-specific Repeat families (SCORs) that are abundant in all the studied lineages. SCORs form complex secondary structures and are located in untranslated regions and introns, but most abundant in intergenic DNA. These repeat families have undergone frequent duplication and degradation, suggesting a 'boom and bust' cycle of invasion and loss. We speculate that due to their surprisingly high sequence identities across deeply diverged corals, physical association with genes, and dynamic evolution, SCORs might have adaptive functions in corals that need to be explored using population genomic and function-based approaches. Copyright © 2017 Elsevier Inc. All rights reserved.

Coastal circulation and potential coral-larval dispersal in Maunalua Bay, O'ahu, Hawaii—Measurements of waves, currents, temperature, and salinity, June-September 2010

USGS Publications Warehouse

Presto, M. Katherine; Storlazzi, Curt D.; Logan, Joshua B.; Reiss, Thomas E.; Rosenberger, Kurt J.

2012-01-01

This report presents a summary of fieldwork conducted in Maunalua Bay, O'ahu, Hawaii to address coral-larval dispersal and recruitment from June through September, 2010. The objectives of this study were to understand the temporal and spatial variations in currents, waves, tides, temperature, and salinity in Maunalua Bay during the summer coral-spawning season of Montipora capitata. Short-term vessel surveys and satellite-tracked drifters were deployed to measure currents during the June 2010 spawning event and to supplement the longer-term measurements of currents and water-column properties by fixed, bottom-mounted instruments deployed in Maunalua Bay. These data show that currents at the surface and just below the surface where coral larvae are found are often oriented in opposite directions due primarily to tidal and trade-winds forcing as the primary mechanisms of circulation in the bay. These data extend our understanding of coral-larvae dispersal patterns due to tidal and wind-driven currents and may be applicable to larvae of other Hawaiian corals.

El Niño and coral larval dispersal across the eastern Pacific marine barrier

NASA Astrophysics Data System (ADS)

Wood, S.; Baums, I. B.; Paris, C. B.; Ridgwell, A.; Kessler, W. S.; Hendy, E. J.

2016-08-01

More than 5,000 km separates the frequently disturbed coral reefs of the Eastern Tropical Pacific (ETP) from western sources of population replenishment. It has been hypothesized that El Niño events facilitate eastward dispersal across this East Pacific Barrier (EPB). Here we present a biophysical coral larval dispersal model driven by 14.5 years of high-resolution surface ocean current data including the extreme 1997-1998 El Niño. We find no eastward cross-EPB connections over this period, which implies that ETP coral populations decimated by the 1998 bleaching event can only have recovered from eastern Pacific sources, in congruence with genetic data. Instead, rare connections between eastern and central Pacific reefs are simulated in a westward direction. Significant complexity and variability in the surface flows transporting larvae mean that generalized upper-ocean circulation patterns are poor descriptors of inter-regional connectivity, complicating the assessment of how climate change will impact coral gene flow Pacific wide.

El Niño and coral larval dispersal across the eastern Pacific marine barrier

PubMed Central

Wood, S.; Baums, I. B.; Paris, C. B.; Ridgwell, A.; Kessler, W. S.; Hendy, E. J.

2016-01-01

More than 5,000 km separates the frequently disturbed coral reefs of the Eastern Tropical Pacific (ETP) from western sources of population replenishment. It has been hypothesized that El Niño events facilitate eastward dispersal across this East Pacific Barrier (EPB). Here we present a biophysical coral larval dispersal model driven by 14.5 years of high-resolution surface ocean current data including the extreme 1997–1998 El Niño. We find no eastward cross-EPB connections over this period, which implies that ETP coral populations decimated by the 1998 bleaching event can only have recovered from eastern Pacific sources, in congruence with genetic data. Instead, rare connections between eastern and central Pacific reefs are simulated in a westward direction. Significant complexity and variability in the surface flows transporting larvae mean that generalized upper-ocean circulation patterns are poor descriptors of inter-regional connectivity, complicating the assessment of how climate change will impact coral gene flow Pacific wide. PMID:27550393

Skeletal mineralogy of newly settling Acropora millepora (Scleractinia) coral recruits

NASA Astrophysics Data System (ADS)

Clode, P. L.; Lema, K.; Saunders, M.; Weiner, S.

2011-03-01

Knowledge of skeletogenesis in scleractinian corals is central to reconstructing past ocean and climate histories, assessing and counteracting future climate and ocean acidification impacts upon coral reefs, and determining the taxonomy and evolutionary path of the Scleractinia. To better understand skeletogenesis and mineralogy in extant scleractinian corals, we have investigated the nature of the initial calcium carbonate skeleton deposited by newly settling coral recruits. Settling Acropora millepora larvae were sampled daily for 10 days from initial attachment, and the carbonate mineralogy of their newly deposited skeletons was investigated. Bulk analyses using Raman and infrared spectroscopic methods revealed that the skeletons were predominantly comprised of aragonite, with no evidence of calcite or an amorphous precursor phase, although presence of the latter cannot be discounted. Sensitive selected area electron diffraction analyses of sub-micron areas of skeletal regions further consolidated these data. These findings help to address the uncertainty surrounding reported differences in carbonate mineralogy between larval and adult extant coral skeletons by indicating that skeletons of new coral recruits share the same aragonitic mineralogy as those of their mature counterparts. In this respect, we can expect that skeletogenesis in both larval and mature growth stages of scleractinian corals will be similarly affected by ocean acidification and predicted environmental changes.

Exploring variable patterns of density-dependent larval settlement among corals with distinct and shared functional traits

NASA Astrophysics Data System (ADS)

Doropoulos, Christopher; Gómez-Lemos, Luis A.; Babcock, Russell C.

2018-03-01

Coral settlement is a key process for the recovery and maintenance of coral reefs, yet interspecific variations in density-dependent settlement are unknown. Settlement of the submassive Goniastrea retiformis and corymbose Acropora digitifera and A. millepora was quantified at densities ranging from 1 to 50 larvae per 20 mL from 110 to 216 h following spawning. Settlement patterns were distinct for each species. Goniastrea settlement was rapid and increased linearly with time, whereas both Acropora spp. hardly settled until crustose coralline algae was provided. Both Goniastrea and A. digitifera showed positive density-dependent settlement, but the relationship was exponential for Goniastrea but linear for A. digitifera. Settlement was highest but density independent in A. millepora. Our results suggest that larval density can have significant effects on settler replenishment, and highlight variability in density-dependent settlement among corals with distinct functional traits as well as those with similar functional forms.

Variation in larval properties of the Atlantic brooding coral Porites astreoides between different reef sites in Bermuda

NASA Astrophysics Data System (ADS)

de Putron, Samantha J.; Lawson, Julia M.; White, Kascia Q. L.; Costa, Matthew T.; Geronimus, Miriam V. B.; MacCarthy, Anne

2017-06-01

Recent research has documented phenotypic differences among larvae released from corals with a brooding reproductive mode, both among species and within broods from a single species. We studied larvae released from the common Atlantic coral Porites astreoides in Bermuda to further evaluate phenotypic variability. Inter-site differences were investigated in larvae from conspecifics at a rim and patch reef site. Larvae were collected daily for one lunar cycle from several colonies per site each year over 5 yr. Larval volume varied with reef site of origin, with colonies from the rim reef site producing larger larvae than colonies from the patch reef site. This inter-site variation in larval size could not be explained by corallite size and may be a response to different environmental conditions at the sites. Larvae from both reef sites also varied in size depending on lunar day of release over 4 yr of study. Regardless of site of origin, smaller larvae were released earlier in the lunar cycle. Over 1 yr of study, lipid and zooxanthellae content and settlement success after 48 h covaried with larval size. However, there may be a trade-off between larger larvae and reduced fecundity. Overall, larvae released from colonies from the rim reef site were larger and had greater settlement success than those from colonies from the patch reef site. This study documents larval phenotypic variability and a distinct inter-site difference in larval ecology among conspecifics within the same geographic area, which may have implications for recruitment success, population dynamics, and resilience.

Whole transcriptome analysis of the coral Acropora millepora reveals complex responses to CO₂-driven acidification during the initiation of calcification.

PubMed

Moya, A; Huisman, L; Ball, E E; Hayward, D C; Grasso, L C; Chua, C M; Woo, H N; Gattuso, J-P; Forêt, S; Miller, D J

2012-05-01

The impact of ocean acidification (OA) on coral calcification, a subject of intense current interest, is poorly understood in part because of the presence of symbionts in adult corals. Early life history stages of Acropora spp. provide an opportunity to study the effects of elevated CO(2) on coral calcification without the complication of symbiont metabolism. Therefore, we used the Illumina RNAseq approach to study the effects of acute exposure to elevated CO(2) on gene expression in primary polyps of Acropora millepora, using as reference a novel comprehensive transcriptome assembly developed for this study. Gene ontology analysis of this whole transcriptome data set indicated that CO(2) -driven acidification strongly suppressed metabolism but enhanced extracellular organic matrix synthesis, whereas targeted analyses revealed complex effects on genes implicated in calcification. Unexpectedly, expression of most ion transport proteins was unaffected, while many membrane-associated or secreted carbonic anhydrases were expressed at lower levels. The most dramatic effect of CO(2) -driven acidification, however, was on genes encoding candidate and known components of the skeletal organic matrix that controls CaCO(3) deposition. The skeletal organic matrix effects included elevated expression of adult-type galaxins and some secreted acidic proteins, but down-regulation of other galaxins, secreted acidic proteins, SCRiPs and other coral-specific genes, suggesting specialized roles for the members of these protein families and complex impacts of OA on mineral deposition. This study is the first exhaustive exploration of the transcriptomic response of a scleractinian coral to acidification and provides an unbiased perspective on its effects during the early stages of calcification. © 2012 Blackwell Publishing Ltd.

Cumulative Effects of Nutrient Enrichment and Elevated Temperature Compromise the Early Life History Stages of the Coral Acropora tenuis

PubMed Central

Noonan, Sam H. C.; Willis, Bette L.; Fabricius, Katharina E.; Negri, Andrew P.

2016-01-01

Inshore coral reefs are experiencing the combined pressures of excess nutrient availability associated with coastal activities and warming seawater temperatures. Both pressures are known to have detrimental effects on the early life history stages of hard corals, but studies of their combined effects on early demographic stages are lacking. We conducted a series of experiments to test the combined effects of nutrient enrichment (three levels) and elevated seawater temperature (up to five levels) on early life history stages of the inshore coral Acropora tenuis, a common species in the Indo-Pacific and Red Sea. Gamete fertilization, larval survivorship and larval settlement were all significantly reduced as temperature increased, but only fertilization was further affected by simultaneous nutrient enrichment. Combined high temperatures and nutrient enrichment affected fertilization in an additive manner, whereas embryo abnormalities increased synergistically. Higher than normal temperatures (32°C) increased coral juvenile growth rates 1.6-fold, but mortality also increased by 50%. The co-occurrence of nutrient enrichment with high temperatures reduced juvenile mortality to 36%, ameliorating temperature stress (antagonistic interaction). Overall, the types of effect (additive vs synergistic or antagonistic) and their magnitude varied among life stages. Gamete and embryo stages were more affected by temperature stress and, in some cases, also by nutrient enrichment than juveniles. The data suggest that coastal runoff events might exacerbate the impacts of warming temperatures on fertilization if these events co-occur during corals spawning. The cumulative impacts of simultaneous exposure to nutrient enrichment and elevated temperatures over all early life history stages increases the likelihood for failure of larval supply and recruitment for this coral species. Our results suggest that improving the water quality of river discharges into coastal areas might help to enhance the thermal tolerances of early life history stages in this common coral species. PMID:27575699

Reef-fish larval dispersal patterns validate no-take marine reserve network connectivity that links human communities

NASA Astrophysics Data System (ADS)

Abesamis, Rene A.; Saenz-Agudelo, Pablo; Berumen, Michael L.; Bode, Michael; Jadloc, Claro Renato L.; Solera, Leilani A.; Villanoy, Cesar L.; Bernardo, Lawrence Patrick C.; Alcala, Angel C.; Russ, Garry R.

2017-09-01

Networks of no-take marine reserves (NTMRs) are a widely advocated strategy for managing coral reefs. However, uncertainty about the strength of population connectivity between individual reefs and NTMRs through larval dispersal remains a major obstacle to effective network design. In this study, larval dispersal among NTMRs and fishing grounds in the Philippines was inferred by conducting genetic parentage analysis on a coral-reef fish ( Chaetodon vagabundus). Adult and juvenile fish were sampled intensively in an area encompassing approximately 90 km of coastline. Thirty-seven true parent-offspring pairs were accepted after screening 1978 juveniles against 1387 adults. The data showed all types of dispersal connections that may occur in NTMR networks, with assignments suggesting connectivity among NTMRs and fishing grounds ( n = 35) far outnumbering those indicating self-recruitment ( n = 2). Critically, half (51%) of the inferred occurrences of larval dispersal linked reefs managed by separate, independent municipalities and constituent villages, emphasising the need for nested collaborative management arrangements across management units to sustain NTMR networks. Larval dispersal appeared to be influenced by wind-driven seasonal reversals in the direction of surface currents. The best-fit larval dispersal kernel estimated from the parentage data predicted that 50% of larvae originating from a population would attempt to settle within 33 km, and 95% within 83 km. Mean larval dispersal distance was estimated to be 36.5 km. These results suggest that creating a network of closely spaced (less than a few tens of km apart) NTMRs can enhance recruitment for protected and fished populations throughout the NTMR network. The findings underscore major challenges for regional coral-reef management initiatives that must be addressed with priority: (1) strengthening management of NTMR networks across political or customary boundaries; and (2) achieving adequate population connectivity via larval dispersal to sustain reef-fish populations within these networks.

Chemical mediation of coral larval settlement by crustose coralline algae

PubMed Central

Tebben, J.; Motti, C. A; Siboni, Nahshon; Tapiolas, D. M.; Negri, A. P.; Schupp, P. J.; Kitamura, Makoto; Hatta, Masayuki; Steinberg, P. D.; Harder, T.

2015-01-01

The majority of marine invertebrates produce dispersive larvae which, in order to complete their life cycles, must attach and metamorphose into benthic forms. This process, collectively referred to as settlement, is often guided by habitat-specific cues. While the sources of such cues are well known, the links between their biological activity, chemical identity, presence and quantification in situ are largely missing. Previous work on coral larval settlement in vitro has shown widespread induction by crustose coralline algae (CCA) and in particular their associated bacteria. However, we found that bacterial biofilms on CCA did not initiate ecologically realistic settlement responses in larvae of 11 hard coral species from Australia, Guam, Singapore and Japan. We instead found that algal chemical cues induce identical behavioral responses of larvae as per live CCA. We identified two classes of CCA cell wall-associated compounds – glycoglycerolipids and polysaccharides – as the main constituents of settlement inducing fractions. These algae-derived fractions induce settlement and metamorphosis at equivalent concentrations as present in CCA, both in small scale laboratory assays and under flow-through conditions, suggesting their ability to act in an ecologically relevant fashion to steer larval settlement of corals. Both compound classes were readily detected in natural samples. PMID:26042834

Extreme mitochondrial variation in the Atlantic gall crab Opecarcinus hypostegus (Decapoda: Cryptochiridae) reveals adaptive genetic divergence over Agaricia coral hosts

PubMed Central

van Tienderen, Kaj M.; van der Meij, Sancia E. T.

2017-01-01

The effectiveness of migration in marine species exhibiting a pelagic larval stage is determined by various factors, such as ocean currents, pelagic larval stage duration and active habitat selection. Direct measurement of larval movements is difficult and, consequently, factors determining the gene flow patterns remain poorly understood for many species. Patterns of gene flow play a key role in maintaining genetic homogeneity in a species by dampening the effects of local adaptation. Coral-dwelling gall crabs (Cryptochiridae) are obligate symbionts of stony corals (Scleractinia). Preliminary data showed high genetic diversity on the COI gene for 19 Opecarcinus hypostegus specimens collected off Curaçao. In this study, an additional 176 specimens were sequenced and used to characterize the population structure along the leeward side of Curaçao. Extremely high COI genetic variation was observed, with 146 polymorphic sites and 187 unique haplotypes. To determine the cause of this high genetic diversity, various gene flow scenarios (geographical distance along the coast, genetic partitioning over depth, and genetic differentiation by coral host) were examined. Adaptive genetic divergence across Agariciidae host species is suggested to be the main cause for the observed high intra-specific variance, hypothesised as early signs of speciation in O. hypostegus. PMID:28079106

Density-dependent coral recruitment displays divergent responses during distinct early life-history stages

PubMed Central

Evensen, Nicolas R.; Gómez-Lemos, Luis A.; Babcock, Russell C.

2017-01-01

Population growth involves demographic bottlenecks that regulate recruitment success during various early life-history stages. The success of each early life-history stage can vary in response to population density, interacting with intrinsic (e.g. behavioural) and environmental (e.g. competition, predation) factors. Here, we used the common reef-building coral Acropora millepora to investigate how density-dependence influences larval survival and settlement in laboratory experiments that isolated intrinsic effects, and post-settlement survival in a field experiment that examined interactions with environmental factors. Larval survival was exceptionally high (greater than 80%) and density-independent from 2.5 to 12 days following spawning. By contrast, there was a weak positive effect of larval density on settlement, driven by gregarious behaviour at the highest density. When larval supply was saturated, settlement was three times higher in crevices compared with exposed microhabitats, but a negative relationship between settler density and post-settlement survival in crevices and density-independent survival on exposed surfaces resulted in similar recruit densities just one month following settlement. Moreover, a negative relationship was found between turf algae and settler survival in crevices, whereas gregarious settlement improved settler survival on exposed surfaces. Overall, our findings reveal divergent responses by coral larvae and newly settled recruits to density-dependent regulation, mediated by intrinsic and environmental interactions. PMID:28573015

Effects of parasites on larval and juvenile stages of the coral reef fish Pomacentrus moluccensis

NASA Astrophysics Data System (ADS)

Grutter, A. S.; Cribb, T. H.; McCallum, H.; Pickering, J. L.; McCormick, M. I.

2010-03-01

The ecological role of parasites in the early life-history stages of coral reef fish is far from clear. Parasitism in larval, recently settled and juvenile stages of a coral reef fish damselfish (Pomacentridae) was therefore investigated by quantifying the ontogenetic change in parasite load and comparing the growth rates of parasitized juvenile fish to those of unparasitized ones. Parasite prevalence in two lunar pulses of Pomacentrus moluccensis was 4 and 0% for larval stage fish, 34 and 56% for recently settled fish and 42 and 49% for juveniles. A significant increase in parasite prevalence with age group was found; the most marked increase occurred immediately after larval fish had settled. Standard length did not model prevalence well; as length is a proxy for age, this indicates that the higher prevalence in recently settled and juvenile fish compared with larvae was not a simple result of parasites accumulating with age. In one of three cohorts, there was some evidence that parasitism affected the growth rate of juveniles, as measured by otolith width. The study suggests that settling on the reef exposes young fish to potentially harmful parasites. This supports the idea that the pelagic phase may have the effect of reducing the exposure of young fish to the debilitating effects of parasites.

Bottlenecks to coral recovery in the Seychelles

NASA Astrophysics Data System (ADS)

Chong-Seng, K. M.; Graham, N. A. J.; Pratchett, M. S.

2014-06-01

Processes that affect recovery of coral assemblages require investigation because coral reefs are experiencing a diverse array of more frequent disturbances. Potential bottlenecks to coral recovery include limited larval supply, low rates of settlement, and high mortality of new recruits or juvenile corals. We investigated spatial variation in local abundance of scleractinian corals in the Seychelles at three distinct life history stages (recruits, juveniles, and adults) on reefs with differing benthic conditions. Following widespread coral loss due to the 1998 bleaching event, some reefs are recovering (i.e., relatively high scleractinian coral cover: `coral-dominated'), some reefs have low cover of living macrobenthos and unconsolidated rubble substrates (`rubble-dominated'), and some reefs have high cover of macroalgae (`macroalgal-dominated'). Rates of coral recruitment to artificial settlement tiles were similar across all reef conditions, suggesting that larval supply does not explain differential coral recovery across the three reef types. However, acroporid recruits were absent on macroalgal-dominated reefs (0.0 ± 0.0 recruits tile-1) in comparison to coral-dominated reefs (5.2 ± 1.6 recruits tile-1). Juvenile coral colony density was significantly lower on macroalgal-dominated reefs (2.4 ± 1.1 colonies m-2), compared to coral-dominated reefs (16.8 ± 2.4 m-2) and rubble-dominated reefs (33.1 ± 7.3 m-2), suggesting that macroalgal-dominated reefs have either a bottleneck to successful settlement on the natural substrates or a high post-settlement mortality bottleneck. Rubble-dominated reefs had very low cover of adult corals (10.0 ± 1.7 %) compared to coral-dominated reefs (33.4 ± 3.6 %) despite no statistical difference in their juvenile coral densities. A bottleneck caused by low juvenile colony survivorship on unconsolidated rubble-dominated reefs is possible, or alternatively, recruitment to rubble-dominated reefs has only recently begun. This study identified bottlenecks to recovery of coral assemblages that varied depending on post-disturbance habitat condition.

Nutritional input from dinoflagellate symbionts in reef-building corals is minimal during planula larval life stage

PubMed Central

Kopp, Christophe; Domart-Coulon, Isabelle; Barthelemy, Dominique; Meibom, Anders

2016-01-01

Dispersion of larval offspring is of fundamental ecological importance to sessile marine organisms. Photosymbiotic planulae emitted by many reef-forming corals may travel over large distances before settling to form a new colony. It is not clear whether the metabolic requirements of these planula larvae are met exclusively with lipid and protein reservoirs inherited from the mother colony or when metabolic inputs from their endosymbiotic dinoflagellates become important. Pulse-chase experiments using [13C]bicarbonate and [15N]nitrate, combined with subcellular structural and isotopic imaging of freshly emitted symbiotic larvae from the coral Pocillopora damicornis, show that metabolic input from the dinoflagellates is minimal in the planulae compared with adult colonies. The larvae are essentially lecithotrophic upon emission, indicating that a marked shift in metabolic interaction between the symbiotic partners takes place later during ontogeny. Understanding the cellular processes that trigger and control this metabolic shift, and how climate change might influence it, is a key challenge in coral biology. PMID:27051861

Mesophotic coral-reef environments depress the reproduction of the coral Paramontastraea peresi in the Red Sea

NASA Astrophysics Data System (ADS)

Feldman, Bar; Shlesinger, Tom; Loya, Yossi

2018-03-01

With more than 450 studied species, coral reproduction is a well-known research field. However, the vast majority of coral reproduction research has focused exclusively on shallow reefs. The incentive for the present study was: (1) the recent accelerated global degradation of coral reefs; (2) the growing interest in mesophotic coral ecosystems (MCEs; 30-120 m depth) and their potential to serve as a larval source for shallow reefs; and (3) the lack of information on MCE coral reproduction. Here, we compare the reproduction and ecology of the depth-generalist coral Paramontastraea peresi between shallow (5-10 m) and mesophotic (40-45 m) habitats in the Gulf of Eilat/Aqaba, Red Sea. Field surveys were conducted to assess the living cover, abundance, and size frequency distribution of P. peresi. Four to six colonies from each habitat were sampled monthly between April 2015 and January 2017, and the gametogenesis cycles, fecundity, and oocyte sizes were measured. The reproductive cycle in the MCEs was shorter than in the shallow reef. Despite having larger polyps, the mesophotic colonies contained significantly smaller and fewer oocytes per polyp. In spite of the relatively stable environmental conditions of the MCEs, which may contribute to coral survival, scarcity of sunlight is probably a major energetic impediment to investment in reproduction by P. peresi at mesophotic depths. Further intensive reproductive studies in mesophotic reefs are thus required to assess the ability of corals in this environment to reproduce and constitute a larval source for depleted shallow-water reefs.

Petroleum hydrocarbon toxicity to corals: A review.

PubMed

Turner, Nicholas R; Renegar, D Abigail

2017-06-30

The proximity of coral reefs to coastal urban areas and shipping lanes predisposes corals to petroleum pollution from multiple sources. Previous research has evaluated petroleum toxicity to coral using a variety of methodology, including monitoring effects of acute and chronic spills, in situ exposures, and ex situ exposures with both adult and larval stage corals. Variability in toxicant, bioassay conditions, species and other methodological disparities between studies prevents comprehensive conclusions regarding the toxicity of hydrocarbons to corals. Following standardized protocols and quantifying the concentration and composition of toxicant will aid in comparison of results between studies and extrapolation to actual spills. Copyright © 2017 Elsevier Ltd. All rights reserved.

Factors affecting infection of corals and larval oysters by vibrio coralliilyticus

USDA-ARS?s Scientific Manuscript database

The bacterium Vibrio coralliilyticus can threaten vital reef ecosystems by causing disease in a variety of coral genera, and, for some strains, increases in virulence at elevated water temperatures. In addition, strains of V. coralliilyticus (formally identified as V. tubiashii) have been implicated...

Climate, bleaching and connectivity in the Coral Triangle.

NASA Astrophysics Data System (ADS)

Curchitser, E. N.; Kleypas, J. A.; Castruccio, F. S.; Drenkard, E.; Thompson, D. M.; Pinsky, M. L.

2016-12-01

The Coral Triangle (CT) is the apex of marine biodiversity and supports the livelihoods of millions of people. It is also one of the most threatened of all reef regions in the world. We present results from a series of high-resolution, numerical ocean models designed to address physical and ecological questions relevant to the region's coral communities. The hierarchy of models was designed to optimize the model performance in addressing questions ranging from the role of internal tides in larval connectivity to distinguishing the role of interannual variability from decadal trends in thermal stress leading to mass bleaching events. In this presentation we will show how combining ocean circulation with models of larval dispersal leads to new insights into the interplay of physics and ecology in this complex oceanographic region, which can ultimately be used to inform conservation efforts.

Gene Expression Patterns during the Early Stages of Chemically Induced Larval Metamorphosis and Settlement of the Coral Acropora millepora

PubMed Central

Siboni, Nachshon; Abrego, David; Motti, Cherie A.; Tebben, Jan; Harder, Tilmann

2014-01-01

The morphogenetic transition of motile coral larvae into sessile primary polyps is triggered and genetically programmed upon exposure to environmental biomaterials, such as crustose coralline algae (CCA) and bacterial biofilms. Although the specific chemical cues that trigger coral larval morphogenesis are poorly understood there is much more information available on the genes that play a role in this early life phase. Putative chemical cues from natural biomaterials yielded defined chemical samples that triggered different morphogenetic outcomes: an extract derived from a CCA-associated Pseudoalteromonas bacterium that induced metamorphosis, characterized by non-attached metamorphosed juveniles; and two fractions of the CCA Hydrolithon onkodes (Heydrich) that induced settlement, characterized by attached metamorphosed juveniles. In an effort to distinguish the genes involved in these two morphogenetic transitions, competent larvae of the coral Acropora millepora were exposed to these predictable cues and the expression profiles of 47 coral genes of interest (GOI) were investigated after only 1 hour of exposure using multiplex RT–qPCR. Thirty-two GOI were differentially expressed, indicating a putative role during the early regulation of morphogenesis. The most striking differences were observed for immunity-related genes, hypothesized to be involved in cell recognition and adhesion, and for fluorescent protein genes. Principal component analysis of gene expression profiles resulted in separation between the different morphogenetic cues and exposure times, and not only identified those genes involved in the early response but also those which influenced downstream biological changes leading to larval metamorphosis or settlement. PMID:24632854

Sediment pollution impacts sensory ability and performance of settling coral-reef fish.

PubMed

O'Connor, J Jack; Lecchini, David; Beck, Hayden J; Cadiou, Gwenael; Lecellier, Gael; Booth, David J; Nakamura, Yohei

2016-01-01

Marine organisms are under threat globally from a suite of anthropogenic sources, but the current emphasis on global climate change has deflected the focus from local impacts. While the effect of increased sedimentation on the settlement of coral species is well studied, little is known about the impact on larval fish. Here, the effect of a laterite "red soil" sediment pollutant on settlement behaviour and post-settlement performance of reef fish was tested. In aquarium tests that isolated sensory cues, we found significant olfaction-based avoidance behaviour and disruption of visual cue use in settlement-stage larval fish at 50 mg L(-1), a concentration regularly exceeded in situ during rain events. In situ light trap catches showed lower abundance and species richness in the presence of red soil, but were not significantly different due to high variance in the data. Prolonged exposure to red soil produced altered olfactory cue responses, whereby fish in red soil made a likely maladaptive choice for dead coral compared to controls where fish chose live coral. Other significant effects of prolonged exposure included decreased feeding rates and body condition. These effects on fish larvae reared over 5 days occurred in the presence of a minor drop in pH and may be due to the chemical influence of the sediment. Our results show that sediment pollution of coral reefs may have more complex effects on the ability of larval fish to successfully locate suitable habitat than previously thought, as well as impacting on their post-settlement performance and, ultimately, recruitment success.

Gene expression microarray analysis encompassing metamorphosis and the onset of calcification in the scleractinian coral Montastraea faveolata.

PubMed

Reyes-Bermudez, Alejandro; Desalvo, Michael K; Voolstra, Christian R; Sunagawa, Shinichi; Szmant, Alina M; Iglesias-Prieto, Roberto; Medina, Mónica

2009-01-01

Similar to many marine invertebrates, scleractinian corals experience a dramatic morphological transformation, as well as a habitat switch, upon settlement and metamorphosis. At this time, planula larvae transform from non-calcifying, demersal, motile organisms into sessile, calcifying, benthic juvenile polyps. We performed gene expression microarray analyses between planulae, aposymbiotic primary polyps, and symbiotic adult tissue to elucidate the molecular mechanisms underlying coral metamorphosis and early stages of calcification in the Robust/Short clade scleractinian coral Montastraea faveolata. Among the annotated genes, the most abundant upregulated transcripts in the planula stage are involved in protein synthesis, chromatin assembly and mitochondrial metabolism; the polyp stage, morphogenesis, protein catabolism and organic matrix synthesis; and the adult stage, sexual reproduction, stress response and symbiosis. We also present evidence showing that the planula and adult transcriptomes are more similar to each other than to the polyp transcriptome. Our results also point to a large number of uncharacterized adult coral-specific genes likely involved in coral-specific functions such as symbiosis and calcification.

Maternal effects and Symbiodinium community composition drive differential patterns in juvenile survival in the coral Acropora tenuis

PubMed Central

Willis, Bette L.; Bay, Line K.

2016-01-01

Coral endosymbionts in the dinoflagellate genus Symbiodinium are known to impact host physiology and have led to the evolution of reef-building, but less is known about how symbiotic communities in early life-history stages and their interactions with host parental identity shape the structure of coral communities on reefs. Differentiating the roles of environmental and biological factors driving variation in population demographic processes, particularly larval settlement, early juvenile survival and the onset of symbiosis is key to understanding how coral communities are structured and to predicting how they are likely to respond to climate change. We show that maternal effects (that here include genetic and/or effects related to the maternal environment) can explain nearly 24% of variation in larval settlement success and 5–17% of variation in juvenile survival in an experimental study of the reef-building scleractinian coral, Acropora tenuis. After 25 days on the reef, Symbiodinium communities associated with juvenile corals differed significantly between high mortality and low mortality families based on estimates of taxonomic richness, composition and relative abundance of taxa. Our results highlight that maternal and familial effects significantly explain variation in juvenile survival and symbiont communities in a broadcast-spawning coral, with Symbiodinium type A3 possibly a critical symbiotic partner during this early life stage. PMID:27853562

Impacts of ocean acidification on early life-history stages and settlement of the coral-eating sea star Acanthaster planci.

PubMed

Uthicke, Sven; Pecorino, Danilo; Albright, Rebecca; Negri, Andrew Peter; Cantin, Neal; Liddy, Michelle; Dworjanyn, Symon; Kamya, Pamela; Byrne, Maria; Lamare, Miles

2013-01-01

Coral reefs are marine biodiversity hotspots, but their existence is threatened by global change and local pressures such as land-runoff and overfishing. Population explosions of coral-eating crown of thorns sea stars (COTS) are a major contributor to recent decline in coral cover on the Great Barrier Reef. Here, we investigate how projected near-future ocean acidification (OA) conditions can affect early life history stages of COTS, by investigating important milestones including sperm motility, fertilisation rates, and larval development and settlement. OA (increased pCO2 to 900-1200 µatm pCO2) significantly reduced sperm motility and, to a lesser extent, velocity, which strongly reduced fertilization rates at environmentally relevant sperm concentrations. Normal development of 10 d old larvae was significantly lower under elevated pCO2 but larval size was not significantly different between treatments. Settlement of COTS larvae was significantly reduced on crustose coralline algae (known settlement inducers of COTS) that had been exposed to OA conditions for 85 d prior to settlement assays. Effect size analyses illustrated that reduced settlement may be the largest bottleneck for overall juvenile production. Results indicate that reductions in fertilisation and settlement success alone would reduce COTS population replenishment by over 50%. However, it is unlikely that this effect is sufficient to provide respite for corals from other negative anthropogenic impacts and direct stress from OA and warming on corals.

Effects of thermal stress and nitrate enrichment on the larval performance of two Caribbean reef corals

NASA Astrophysics Data System (ADS)

Serrano, Xaymara M.; Miller, Margaret W.; Hendee, James C.; Jensen, Brittany A.; Gapayao, Justine Z.; Pasparakis, Christina; Grosell, Martin; Baker, Andrew C.

2018-03-01

The effects of multiple stressors on the early life stages of reef-building corals are poorly understood. Elevated temperature is the main physiological driver of mass coral bleaching events, but increasing evidence suggests that other stressors, including elevated dissolved inorganic nitrogen (DIN), may exacerbate the negative effects of thermal stress. To test this hypothesis, we investigated the performance of larvae of Orbicella faveolata and Porites astreoides, two important Caribbean reef coral species with contrasting reproductive and algal transmission modes, under increased temperature and/or elevated DIN. We used a fluorescence-based microplate respirometer to measure the oxygen consumption of coral larvae from both species, and also assessed the effects of these stressors on P. astreoides larval settlement and mortality. Overall, we found that (1) larvae increased their respiration in response to different factors ( O. faveolata in response to elevated temperature and P. astreoides in response to elevated nitrate) and (2) P. astreoides larvae showed a significant increase in settlement as a result of elevated nitrate, but higher mortality under elevated temperature. This study shows how microplate respirometry can be successfully used to assess changes in respiration of coral larvae, and our findings suggest that the effects of thermal stress and nitrate enrichment in coral larvae may be species specific and are neither additive nor synergistic for O. faveolata or P. astreoides. These findings may have important consequences for the recruitment and community reassembly of corals to nutrient-polluted reefs that have been impacted by climate change.

Mediterranean versus Red sea corals facing climate change, a transcriptome analysis

NASA Astrophysics Data System (ADS)

Maor-Landaw, Keren; Waldman Ben-Asher, Hiba; Karako-Lampert, Sarit; Salmon-Divon, Mali; Prada, Fiorella; Caroselli, Erik; Goffredo, Stefano; Falini, Giuseppe; Dubinsky, Zvy; Levy, Oren

2017-02-01

The anthropogenic increase in atmospheric CO2 that drives global warming and ocean acidification raises serious concerns regarding the future of corals, the main carbonate biomineralizers. Here we used transcriptome analysis to study the effect of long-term gradual temperature increase (annual rate), combined with lowered pH values, on a sub-tropical Red Sea coral, Stylophora pistillata, and on a temperate Mediterranean symbiotic coral Balanophyllia europaea. The gene expression profiles revealed a strong effect of both temperature increase and pH decrease implying for synergism response. The temperate coral, exposed to a twice as high range of seasonal temperature fluctuations than the Red Sea species, faced stress more effectively. The compensatory strategy for coping apparently involves deviating cellular resources into a massive up-regulation of genes in general, and specifically of genes involved in the generation of metabolic energy. Our results imply that sub-lethal, prolonged exposure to stress can stimulate evolutionary increase in stress resilience.

Transcriptome profiling of Galaxea fascicularis and its endosymbiont Symbiodinium reveals chronic eutrophication tolerance pathways and metabolic mutualism between partners

PubMed Central

Lin, Zhenyue; Chen, Mingliang; Dong, Xu; Zheng, Xinqing; Huang, Haining; Xu, Xun; Chen, Jianming

2017-01-01

In the South China Sea, coastal eutrophication in the Beibu Gulf has seriously threatened reef habitats by subjecting corals to chronic physiological stress. To determine how coral holobionts may tolerate such conditions, we examined the transcriptomes of healthy colonies of the galaxy coral Galaxea fascicularis and its endosymbiont Symbiodinium from two reef sites experiencing pristine or eutrophied nutrient regimes. We identified 236 and 205 genes that were differentially expressed in eutrophied hosts and symbionts, respectively. Both gene sets included pathways related to stress responses and metabolic interactions. An analysis of genes originating from each partner revealed striking metabolic integration with respect to vitamins, cofactors, amino acids, fatty acids, and secondary metabolite biosynthesis. The expression levels of these genes supported the existence of a continuum of mutualism in this coral-algal symbiosis. Additionally, large sets of transcription factors, cell signal transduction molecules, biomineralization components, and galaxin-related proteins were expanded in G. fascicularis relative to other coral species. PMID:28181581

Settlement success of Favia fragum planulae exposed to different sediment types and concentrations from southern Puerto Rico

EPA Science Inventory

Sedimentation has been reported to adversely affect coral ecosystems, but the precise effects of sediment on coral larval settlement and metamorphosis are not well understood. Planulae from laboratory-cultured Favia fragum colonies were collected and exposed to sediment collected...

Reserve design for uncertain responses of coral reefs to climate change.

PubMed

Mumby, Peter J; Elliott, Ian A; Eakin, C Mark; Skirving, William; Paris, Claire B; Edwards, Helen J; Enríquez, Susana; Iglesias-Prieto, Roberto; Cherubin, Laurent M; Stevens, Jamie R

2011-02-01

Rising sea temperatures cause mass coral bleaching and threaten reefs worldwide. We show how maps of variations in thermal stress can be used to help manage reefs for climate change. We map proxies of chronic and acute thermal stress and develop evidence-based hypotheses for the future response of corals to each stress regime. We then incorporate spatially realistic predictions of larval connectivity among reefs of the Bahamas and apply novel reserve design algorithms to create reserve networks for a changing climate. We show that scales of larval dispersal are large enough to connect reefs from desirable thermal stress regimes into a reserve network. Critically, we find that reserve designs differ according to the anticipated scope for phenotypic and genetic adaptation in corals, which remains uncertain. Attempts to provide a complete reserve design that hedged against different evolutionary outcomes achieved limited success, which emphasises the importance of considering the scope for adaptation explicitly. Nonetheless, 15% of reserve locations were selected under all evolutionary scenarios, making them a high priority for early designation. Our approach allows new insights into coral holobiont adaptation to be integrated directly into an adaptive approach to management. © 2010 Blackwell Publishing Ltd/CNRS.

Red fluorescent protein responsible for pigmentation in trematode-infected Porites compressa tissues.

PubMed

Palmer, Caroline V; Roth, Melissa S; Gates, Ruth D

2009-02-01

Reports of coral disease have increased dramatically over the last decade; however, the biological mechanisms that corals utilize to limit infection and resist disease remain poorly understood. Compromised coral tissues often display non-normal pigmentation that potentially represents an inflammation-like response, although these pigments remain uncharacterized. Using spectral emission analysis and cryo-histological and electrophoretic techniques, we investigated the pink pigmentation associated with trematodiasis, infection with Podocotyloides stenometre larval trematode, in Porites compressa. Spectral emission analysis reveals that macroscopic areas of pink pigmentation fluoresce under blue light excitation (450 nm) and produce a broad emission peak at 590 nm (+/-6) with a 60-nm full width at half maximum. Electrophoretic protein separation of pigmented tissue extract confirms the red fluorescence to be a protein rather than a low-molecular-weight compound. Histological sections demonstrate green fluorescence in healthy coral tissue and red fluorescence in the trematodiasis-compromised tissue. The red fluorescent protein (FP) is limited to the epidermis, is not associated with cells or granules, and appears unstructured. These data collectively suggest that the red FP is produced and localized in tissue infected by larval trematodes and plays a role in the immune response in corals.

Ocean circulation drives heterogeneous recruitments and connectivity among coral populations on the North West Shelf of Australia

NASA Astrophysics Data System (ADS)

Feng, Ming; Colberg, Frank; Slawinski, Dirk; Berry, Oliver; Babcock, Russ

2016-12-01

The North West Shelf (NWS) of Australia features extensive and globally significant fringing coral reef ecosystems with high levels of endemism and consequently has received significant conservation efforts in the form of Marine Parks. The shelf circulation on the NWS is dominated by the southwestward-flowing Holloway Current during austral autumn-winter and by the northeastward monsoonal currents during austral summer. Intraseasonal Oscillation and short-term wind variability also influence advection processes on the NWS. These circulation processes are likely to determine demographic inter-dependencies among reef systems in the region, but the extent and spatial variability of the inter-dependence are not well understood. In this study, we used a 3-dimensional, hydrostatic, primitive equations model, to simulate the shelf circulation on the NWS at 1 km horizontal resolution during 2004-2009. We then used a particle tracking model based on the shelf circulation model to simulate larval dispersal in a representative coral species, Acropora millepora, among the 3430 coral reefs on the NWS during its autumn mass spawning. Model results predicted that settling larvae typically reach suitable reef within 10 days of spawning, with a predominantly southwestward tendency of transport. There was significant spatial heterogeneity in larval settlements and the Dampier Archipelago areas seemed to be more isolated from the rest of the NWS. Year-to-year variations of larval dispersals were sensitive to the seasonal and intraseasonal variations of alongshore winds: mass spawning in late March would expose the Dampier Archipelago area to the Holloway Current onset, resulting in it being an occasional source region of larval supply for the rest of the NWS to the southwest; intraseasonal northeastward wind pulses coinciding with the mass larval spawning would bring larvae from coastal regions to the Dampier Archipelago on rare occasions. By aggregating the reefs into 47 subregions, we estimated that the mean rate of self-seeding within the subregions (as a proportion of total supply) was 22% (range from 99% to < 1%). Subregions with high retention (as a proportion of total egg production) were not necessarily those with the highest levels of overall larval settlements. Such high "sink" subregions were also some of the most important "source" subregions. Most of the important source and sink subregions were found to be outside existing marine parks, however, existing marine parks did contain subregions with some of the highest levels of self-seeding and larval retention.

Larvae of the coral eating crown-of-thorns starfish, Acanthaster planci in a warmer-high CO2 ocean.

PubMed

Kamya, Pamela Z; Dworjanyn, Symon A; Hardy, Natasha; Mos, Benjamin; Uthicke, Sven; Byrne, Maria

2014-11-01

Outbreaks of crown-of-thorns starfish (COTS), Acanthaster planci, contribute to major declines of coral reef ecosystems throughout the Indo-Pacific. As the oceans warm and decrease in pH due to increased anthropogenic CO2 production, coral reefs are also susceptible to bleaching, disease and reduced calcification. The impacts of ocean acidification and warming may be exacerbated by COTS predation, but it is not known how this major predator will fare in a changing ocean. Because larval success is a key driver of population outbreaks, we investigated the sensitivities of larval A. planci to increased temperature (2-4 °C above ambient) and acidification (0.3-0.5 pH units below ambient) in flow-through cross-factorial experiments (3 temperature × 3 pH/pCO2 levels). There was no effect of increased temperature or acidification on fertilization or very early development. Larvae reared in the optimal temperature (28 °C) were the largest across all pH treatments. Development to advanced larva was negatively affected by the high temperature treatment (30 °C) and by both experimental pH levels (pH 7.6, 7.8). Thus, planktonic life stages of A. planci may be negatively impacted by near-future global change. Increased temperature and reduced pH had an additive negative effect on reducing larval size. The 30 °C treatment exceeded larval tolerance regardless of pH. As 30 °C sea surface temperatures may become the norm in low latitude tropical regions, poleward migration of A. planci may be expected as they follow optimal isotherms. In the absence of acclimation or adaptation, declines in low latitude populations may occur. Poleward migration will be facilitated by strong western boundary currents, with possible negative flow-on effects on high latitude coral reefs. The contrasting responses of the larvae of A. planci and those of its coral prey to ocean acidification and warming are considered in context with potential future change in tropical reef ecosystems. © 2014 John Wiley & Sons Ltd.

Larval Connectivity and the International Management of Fisheries

PubMed Central

Kough, Andrew S.; Paris, Claire B.; Butler, Mark J.

2013-01-01

Predicting the oceanic dispersal of planktonic larvae that connect scattered marine animal populations is difficult, yet crucial for management of species whose movements transcend international boundaries. Using multi-scale biophysical modeling techniques coupled with empirical estimates of larval behavior and gamete production, we predict and empirically verify spatio-temporal patterns of larval supply and describe the Caribbean-wide pattern of larval connectivity for the Caribbean spiny lobster (Panulirus argus), an iconic coral reef species whose commercial value approaches $1 billion USD annually. Our results provide long sought information needed for international cooperation in the management of marine resources by identifying lobster larval connectivity and dispersal pathways throughout the Caribbean. Moreover, we outline how large-scale fishery management could explicitly recognize metapopulation structure by considering larval transport dynamics and pelagic larval sanctuaries. PMID:23762273

Transcriptomic analysis of the response of Acropora millepora to hypo-osmotic stress provides insights into DMSP biosynthesis by corals.

PubMed

Aguilar, Catalina; Raina, Jean-Baptiste; Motti, Cherie A; Fôret, Sylvain; Hayward, David C; Lapeyre, Bruno; Bourne, David G; Miller, David J

2017-08-14

Dimethylsulfoniopropionate (DMSP) is a small sulphur compound which is produced in prodigious amounts in the oceans and plays a pivotal role in the marine sulfur cycle. Until recently, DMSP was believed to be synthesized exclusively by photosynthetic organisms; however we now know that corals and specific bacteria can also produce this compound. Corals are major sources of DMSP, but the molecular basis for its biosynthesis is unknown in these organisms. Here we used salinity stress, which is known to trigger DMSP production in other organisms, in conjunction with transcriptomics to identify coral genes likely to be involved in DMSP biosynthesis. We focused specifically on both adults and juveniles of the coral Acropora millepora: after 24 h of exposure to hyposaline conditions, DMSP concentrations increased significantly by 2.6 fold in adult corals and 1.2 fold in juveniles. Concomitantly, candidate genes enabling each of the necessary steps leading to DMSP production were up-regulated. The data presented strongly suggest that corals use an algal-like pathway to generate DMSP from methionine, and are able to rapidly change expression of the corresponding genes in response to environmental stress. However, our data also indicate that DMSP is unlikely to function primarily as an osmolyte in corals, instead potentially serving as a scavenger of ROS and as a molecular sink for excess methionine produced as a consequence of proteolysis and osmolyte catabolism in corals under hypo-osmotic conditions.

Stepwise Evolution of Coral Biomineralization Revealed with Genome-Wide Proteomics and Transcriptomics

PubMed Central

Sawada, Hitoshi; Satoh, Noriyuki

2016-01-01

Despite the importance of stony corals in many research fields related to global issues, such as marine ecology, climate change, paleoclimatogy, and metazoan evolution, very little is known about the evolutionary origin of coral skeleton formation. In order to investigate the evolution of coral biomineralization, we have identified skeletal organic matrix proteins (SOMPs) in the skeletal proteome of the scleractinian coral, Acropora digitifera, for which large genomic and transcriptomic datasets are available. Scrupulous gene annotation was conducted based on comparisons of functional domain structures among metazoans. We found that SOMPs include not only coral-specific proteins, but also protein families that are widely conserved among cnidarians and other metazoans. We also identified several conserved transmembrane proteins in the skeletal proteome. Gene expression analysis revealed that expression of these conserved genes continues throughout development. Therefore, these genes are involved not only skeleton formation, but also in basic cellular functions, such as cell-cell interaction and signaling. On the other hand, genes encoding coral-specific proteins, including extracellular matrix domain-containing proteins, galaxins, and acidic proteins, were prominently expressed in post-settlement stages, indicating their role in skeleton formation. Taken together, the process of coral skeleton formation is hypothesized as: 1) formation of initial extracellular matrix between epithelial cells and substrate, employing pre-existing transmembrane proteins; 2) additional extracellular matrix formation using novel proteins that have emerged by domain shuffling and rapid molecular evolution and; 3) calcification controlled by coral-specific SOMPs. PMID:27253604

Transcriptomic Analysis of Neuropeptides and Peptide Hormones in the Barnacle Balanus amphitrite: Evidence of Roles in Larval Settlement

PubMed Central

Yan, Xing-Cheng; Chen, Zhang-Fan; Sun, Jin; Matsumura, Kiyotaka; Wu, Rudolf S. S.; Qian, Pei-Yuan

2012-01-01

The barnacle Balanus amphitrite is a globally distributed marine crustacean and has been used as a model species for intertidal ecology and biofouling studies. Its life cycle consists of seven planktonic larval stages followed by a sessile juvenile/adult stage. The transitional processes between larval stages and juveniles are crucial for barnacle development and recruitment. Although some studies have been conducted on the neuroanatomy and neuroactive substances of the barnacle, a comprehensive understanding of neuropeptides and peptide hormones remains lacking. To better characterize barnacle neuropeptidome and its potential roles in larval settlement, an in silico identification of putative transcripts encoding neuropeptides/peptide hormones was performed, based on transcriptome of the barnacle B. amphitrite that has been recently sequenced. Potential cleavage sites andstructure of mature peptides were predicted through homology search of known arthropod peptides. In total, 16 neuropeptide families/subfamilies were predicted from the barnacle transcriptome, and 14 of them were confirmed as genuine neuropeptides by Rapid Amplification of cDNA Ends. Analysis of peptide precursor structures and mature sequences showed that some neuropeptides of B. amphitrite are novel isoforms and shared similar characteristics with their homologs from insects. The expression profiling of predicted neuropeptide genes revealed that pigment dispersing hormone, SIFamide, calcitonin, and B-type allatostatin had the highest expression level in cypris stage, while tachykinin-related peptide was down regulated in both cyprids and juveniles. Furthermore, an inhibitor of proprotein convertase related to peptide maturation effectively delayed larval metamorphosis. Combination of real-time PCR results and bioassay indicated that certain neuropeptides may play an important role in cypris settlement. Overall, new insight into neuropeptides/peptide hormones characterized in this study shall provide a platform for unraveling peptidergic control of barnacle larval behavior and settlement process. PMID:23056329

Rising CO2 concentrations affect settlement behaviour of larval damselfishes

NASA Astrophysics Data System (ADS)

Devine, B. M.; Munday, P. L.; Jones, G. P.

2012-03-01

Reef fish larvae actively select preferred benthic habitat, relying on olfactory, visual and acoustic cues to discriminate between microhabitats at settlement. Recent studies show exposure to elevated carbon dioxide (CO2) impairs olfactory cue recognition in larval reef fishes. However, whether this alters the behaviour of settling fish or disrupts habitat selection is unknown. Here, the effect of elevated CO2 on larval behaviour and habitat selection at settlement was tested in three species of damselfishes (family Pomacentridae) that differ in their pattern of habitat use: Pomacentrus amboinensis (a habitat generalist), Pomacentrus chrysurus (a rubble specialist) and Pomacentrus moluccensis (a live coral specialist). Settlement-stage larvae were exposed to current-day CO2 levels or CO2 concentrations that could occur by 2100 (700 and 850 ppm) based on IPCC emission scenarios. First, pair-wise choice tests were performed using a two-channel flume chamber to test olfactory discrimination between hard coral, soft coral and coral rubble habitats. The habitat selected by settling fish was then compared among treatments using a multi-choice settlement experiment conducted overnight. Finally, settlement timing between treatments was compared across two lunar cycles for one of the species, P. chrysurus. Exposure to elevated CO2 disrupted the ability of larvae to discriminate between habitat odours in olfactory trials. However, this had no effect on the habitats selected at settlement when all sensory cues were available. The timing of settlement was dramatically altered by CO2 exposure, with control fish exhibiting peak settlement around the new moon, whereas fish exposed to 850 ppm CO2 displaying highest settlement rates around the full moon. These results suggest larvae can rely on other sensory information, such as visual cues, to compensate for impaired olfactory ability when selecting settlement habitat at small spatial scales. However, rising CO2 could cause larvae to settle at unfavourable times, with potential consequences for larval survival and population replenishment.

Tolerance to Elevated Temperature and Ocean Acidification of the Larvae of the Solitary Corals Fungia fungites (Linnaues, 1758) and Lithophyllon repanda (Dana, 1846).

PubMed

Baria, Maria Vanessa B; Kurihara, Haruko; Harii, Saki

2015-10-01

Increase in atmospheric CO₂is the main driver of global climate change and is projected to elevate sea surface temperature by at least 2°C and to decrease oceanic pH by 0.3 to 0.4 units by the end of the century. These factors seriously threaten coral reef ecosystems worldwide. In Okinawa, solitary corals are an important feature of the coral community structure. While previous studies on the effects of ocean warming (OW), ocean acidification (OA) and its combination on larval survival focused on colonial coral species, the present study assessed the effect of high temperature on larvae from solitary corals. In this study, we examined the influence of OW (control = 28°C; control +3 = 31°C; control + 6 = 34°C) and OA (control, pCO₂= 400 to 500 μatm; medium, pCO₂= 1000 to 1300 μatm; high, pCO₂= 1700 to 2200 μatm) on the larval survival of two solitary corals, Fungia fungites and Lithophyllon repanda for eight days. Results showed that F. fungites was neither affected by OW, OA, nor its combination. Similarly, survival of L. repanda was not affected by OA however it was significantly affected by temperature. Temperature tolerance varies between species; L. repanda (+3°C above ambient) has lower tolerance than F. fungites (+6°C above ambient). This observation suggests that fungiid larvae had higher tolerance to elevated temperature stress relative to other scleractinian corals. With the projected increase in OW and OA in the future, fungiidsmay retain good potential to widely disperse and successfully recruit to natal and other neighbouring reefs.

The immunotranscriptome of the Caribbean reef-building coral Pseudodiploria strigosa.

PubMed

Ocampo, Iván D; Zárate-Potes, Alejandra; Pizarro, Valeria; Rojas, Cristian A; Vera, Nelson E; Cadavid, Luis F

2015-09-01

The viability of coral reefs worldwide has been seriously compromised in the last few decades due in part to the emergence of coral diseases of infectious nature. Despite important efforts to understand the etiology and the contribution of environmental factors associated to coral diseases, the mechanisms of immune response in corals are just beginning to be studied systematically. In this study, we analyzed the set of conserved immune response genes of the Caribbean reef-building coral Pseudodiploria strigosa by Illumina-based transcriptome sequencing and annotation of healthy colonies challenged with whole live Gram-positive and Gram-negative bacteria. Searching the annotated transcriptome with immune-related terms yielded a total of 2782 transcripts predicted to encode conserved immune-related proteins that were classified into three modules: (a) the immune recognition module, containing a wide diversity of putative pattern recognition receptors including leucine-rich repeat-containing proteins, immunoglobulin superfamily receptors, representatives of various lectin families, and scavenger receptors; (b) the intracellular signaling module, containing components from the Toll-like receptor, transforming growth factor, MAPK, and apoptosis signaling pathways; and (3) the effector module, including the C3 and factor B complement components, a variety of proteases and protease inhibitors, and the melanization-inducing phenoloxidase. P. strigosa displays a highly variable and diverse immune recognition repertoire that has likely contributed to its resilience to coral diseases.

Elevated temperature alters the lunar timing of Planulation in the brooding coral Pocillopora damicornis.

PubMed

Crowder, Camerron M; Liang, Wei-Lo; Weis, Virginia M; Fan, Tung-Yung

2014-01-01

Reproductive timing in corals is associated with environmental variables including temperature, lunar periodicity, and seasonality. Although it is clear that these variables are interrelated, it remains unknown if one variable in particular acts as the proximate signaler for gamete and or larval release. Furthermore, in an era of global warming, the degree to which increases in ocean temperatures will disrupt normal reproductive patterns in corals remains unknown. Pocillopora damicornis, a brooding coral widely distributed in the Indo-Pacific, has been the subject of multiple reproductive ecology studies that show correlations between temperature, lunar periodicity, and reproductive timing. However, to date, no study has empirically measured changes in reproductive timing associated with increased seawater temperature. In this study, the effect of increased seawater temperature on the timing of planula release was examined during the lunar cycles of March and June 2012. Twelve brooding corals were removed from Hobihu reef in Nanwan Bay, southern Taiwan and placed in 23 and 28°C controlled temperature treatment tanks. For both seasons, the timing of planulation was found to be plastic, with the high temperature treatment resulting in significantly earlier peaks of planula release compared to the low temperature treatment. This suggests that temperature alone can influence the timing of larval release in Pocillopora damicornis in Nanwan Bay. Therefore, it is expected that continued increases in ocean temperature will result in earlier timing of reproductive events in corals, which may lead to either variations in reproductive success or phenotypic acclimatization.

Elevated Temperature Alters the Lunar Timing of Planulation in the Brooding Coral Pocillopora damicornis

PubMed Central

Crowder, Camerron M.; Liang, Wei-Lo; Weis, Virginia M.; Fan, Tung-Yung

2014-01-01

Reproductive timing in corals is associated with environmental variables including temperature, lunar periodicity, and seasonality. Although it is clear that these variables are interrelated, it remains unknown if one variable in particular acts as the proximate signaler for gamete and or larval release. Furthermore, in an era of global warming, the degree to which increases in ocean temperatures will disrupt normal reproductive patterns in corals remains unknown. Pocillopora damicornis, a brooding coral widely distributed in the Indo-Pacific, has been the subject of multiple reproductive ecology studies that show correlations between temperature, lunar periodicity, and reproductive timing. However, to date, no study has empirically measured changes in reproductive timing associated with increased seawater temperature. In this study, the effect of increased seawater temperature on the timing of planula release was examined during the lunar cycles of March and June 2012. Twelve brooding corals were removed from Hobihu reef in Nanwan Bay, southern Taiwan and placed in 23 and 28°C controlled temperature treatment tanks. For both seasons, the timing of planulation was found to be plastic, with the high temperature treatment resulting in significantly earlier peaks of planula release compared to the low temperature treatment. This suggests that temperature alone can influence the timing of larval release in Pocillopora damicornis in Nanwan Bay. Therefore, it is expected that continued increases in ocean temperature will result in earlier timing of reproductive events in corals, which may lead to either variations in reproductive success or phenotypic acclimatization. PMID:25329546

First description of the neuro-anatomy of a larval coral reef fish Amphiprion ocellaris.

PubMed

Jacob, H; Metian, M; Brooker, R M; Duran, E; Nakamura, N; Roux, N; Masanet, P; Soulat, O; Lecchini, D

2016-09-01

The present study described the neuro-anatomy of a larval coral reef fish Amphiprion ocellaris and hypothesized that morphological changes during the transition from the oceanic environment to a reef environment (i.e. recruitment) have the potential to be driven by changes to environmental conditions and associated changes to cognitive requirements. Quantitative comparisons were made of the relative development of three specific brain areas (telencephalon, mesencephalon and cerebellum) between 6 days post-hatch (dph) larvae (oceanic phase) and 11 dph (at reef recruitment). The results showed that 6 dph larvae had at least two larger structures (telencephalon and mesencephalon) than 11 dph larvae, while the size of cerebellum remained identical. These results suggest that the structure and organization of the brain may reflect the cognitive demands at every stage of development. This study initiates analysis of the relationship between behavioural ecology and neuroscience in coral reef fishes. © 2016 The Fisheries Society of the British Isles.

Transcriptome deep-sequencing and clustering of expressed isoforms from Favia corals

PubMed Central

2013-01-01

Background Genomic and transcriptomic sequence data are essential tools for tackling ecological problems. Using an approach that combines next-generation sequencing, de novo transcriptome assembly, gene annotation and synthetic gene construction, we identify and cluster the protein families from Favia corals from the northern Red Sea. Results We obtained 80 million 75 bp paired-end cDNA reads from two Favia adult samples collected at 65 m (Fav1, Fav2) on the Illumina GA platform, and generated two de novo assemblies using ABySS and CAP3. After removing redundancy and filtering out low quality reads, our transcriptome datasets contained 58,268 (Fav1) and 62,469 (Fav2) contigs longer than 100 bp, with N50 values of 1,665 bp and 1,439 bp, respectively. Using the proteome of the sea anemone Nematostella vectensis as a reference, we were able to annotate almost 20% of each dataset using reciprocal homology searches. Homologous clustering of these annotated transcripts allowed us to divide them into 7,186 (Fav1) and 6,862 (Fav2) homologous transcript clusters (E-value ≤ 2e-30). Functional annotation categories were assigned to homologous clusters using the functional annotation of Nematostella vectensis. General annotation of the assembled transcripts was improved 1-3% using the Acropora digitifera proteome. In addition, we screened these transcript isoform clusters for fluorescent proteins (FPs) homologs and identified seven potential FP homologs in Fav1, and four in Fav2. These transcripts were validated as bona fide FP transcripts via robust fluorescence heterologous expression. Annotation of the assembled contigs revealed that 1.34% and 1.61% (in Fav1 and Fav2, respectively) of the total assembled contigs likely originated from the corals’ algal symbiont, Symbiodinium spp. Conclusions Here we present a study to identify the homologous transcript isoform clusters from the transcriptome of Favia corals using a far-related reference proteome. Furthermore, the symbiont-derived transcripts were isolated from the datasets and their contribution quantified. This is the first annotated transcriptome of the genus Favia, a major increase in genomics resources available in this important family of corals. PMID:23937070

Analyses of Corallimorpharian Transcriptomes Provide New Perspectives on the Evolution of Calcification in the Scleractinia (Corals).

PubMed

Lin, Mei-Fang; Moya, Aurelie; Ying, Hua; Chen, Chaolun Allen; Cooke, Ira; Ball, Eldon E; Forêt, Sylvain; Miller, David J

2017-01-01

Corallimorpharians (coral-like anemones) have a close phylogenetic relationship with scleractinians (hard corals) and can potentially provide novel perspectives on the evolution of biomineralization within the anthozoan subclass Hexacorallia. A survey of the transcriptomes of three representative corallimorpharians led to the identification of homologs of some skeletal organic matrix proteins (SOMPs) previously considered to be restricted to corals.Carbonic anhydrases (CAs), which are ubiquitous proteins involved in CO2 trafficking, are involved in both coral calcification and photosynthesis by endosymbiotic Symbiodinium (zooxanthellae). These multiple roles are assumed to place increased demands on the CA repertoire and have presumably driven the elaboration of the complex CA repertoires typical of corals (note that "corals" are defined here as reef-building Scleractinia). Comparison of the CA inventories of corallimorpharians with those of corals reveals that corals have specifically expanded the secreted and membrane-associated type CAs, whereas similar complexity is observed in the two groups with respect to other CA types.Comparison of the CA complement of the nonsymbiotic corallimorph Corynactis australis with that of Ricordea yuma, a corallimorph which normally hosts Symbiodinium, reveals similar numbers and distribution of CA types and suggests that an expansion of the CA repertoire has been necessary to enable calcification but may not be a requirement to enable symbiosis. Consistent with this idea, preliminary analysis suggests that the CA complexity of zooxanthellate and nonzooxanthellate sea anemones is similar.The comparisons above suggest that although there are relatively few new genes in the skeletal organic matrix of corals (which controls the skeleton deposition process), the evolution of calcification required an expanded repertoire of secreted and membrane-associated CAs. © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Auditory sensitivity in settlement-stage larvae of coral reef fishes

NASA Astrophysics Data System (ADS)

Wright, K. J.; Higgs, D. M.; Cato, D. H.; Leis, J. M.

2010-03-01

The larval phase of most species of coral reef fishes is spent away from the reef in the pelagic environment. At the time of settlement, these larvae need to locate a reef, and recent research indicates that sound emanating from reefs may act as a cue to guide them. Here, the auditory abilities of settlement-stage larvae of four species of coral reef fishes (families Pomacentridae, Lutjanidae and Serranidae) and similar-sized individuals of two pelagic species (Carangidae) were tested using an electrophysiological technique, auditory brainstem response (ABR). Five of the six species heard frequencies in the 100-2,000 Hz range, whilst one carangid species did not detect frequencies higher than 800 Hz. The audiograms of the six species were of similar shape, with best hearing at lower frequencies between 100 and 300 Hz. Strong within-species differences were found in hearing sensitivity both among the coral reef species and among the pelagic species. Larvae of the coral reef species had significantly more sensitive hearing than the larvae of the pelagic species. The results suggest that settlement-stage larval reef fishes may be able to detect reef sounds at distances of a few 100 m. If true hearing thresholds are lower than ABR estimates, as indicated in some comparisons of ABR and behavioural methods, the detection distances would be much larger.

Impact of micropredatory gnathiid isopods on young coral reef fishes

NASA Astrophysics Data System (ADS)

Grutter, A. S.; Pickering, J. L.; McCallum, H.; McCormick, M. I.

2008-09-01

The ecological role of parasites in the early life-history stages of coral reef fish, and whether this varies between fish with and without a pelagic phase, was investigated. The susceptibility to, and effect of reef-based micropredatory gnathiid isopods on larval, recently settled, and juvenile fishes was tested using two damselfishes (Pomacentridae): Neopomacentrus azysron, which has pelagic larvae, and Acanthochromis polyacanthus, which does not. When larval and recently settled stages of N. azysron and very young A. polyacanthus juveniles (smaller than larval N. azysron) were exposed to one or three gnathiids, the proportion of infections did not vary significantly among the three host types or between the number of gnathiids to which the fish were exposed. The overall infection was 35%. Mortality, however, differed among the three gnathiid-exposed host types with most deaths occurring in larval N. azysron; no mortalities occurred for recently settled N. azysron exposed to one or three gnathiids, and A. polyacanthus exposed to one gnathiid. Mortality did not differ significantly between larval N. azysron and A. polyacanthus juveniles, failing to provide support for the hypothesis that reef-based A. polyacanthus juveniles are better adapted to gnathiid attack than fish with a pelagic phase. The study suggests that settling on the reef exposes young fish to potentially deadly micropredators. This supports the idea that the pelagic phase may allow young fish to avoid reef-based parasites.

Reproductive biology of the deep brooding coral Seriatopora hystrix: Implications for shallow reef recovery.

PubMed

Prasetia, Rian; Sinniger, Frederic; Hashizume, Kaito; Harii, Saki

2017-01-01

Mesophotic coral ecosystems (MCEs, between 30 and 150 m depth) are hypothesized to contribute to the recovery of degraded shallow reefs through sexually produced larvae (referred to as Deep Reef Refuge Hypothesis). In Okinawa, Japan, the brooder coral Seriatopora hystrix was reported to be locally extinct in a shallow reef while it was found abundant at a MCE nearby. In this context, S. hystrix represents a key model to test the Deep Reef Refuge Hypothesis and to understand the potential contribution of mesophotic corals to shallow coral reef recovery. However, the reproductive biology of mesophotic S. hystrix and its potential to recolonize shallow reefs is currently unknown. This study reports for the first time, different temporal scales of reproductive periodicity and larval settlement of S. hystrix from an upper mesophotic reef (40 m depth) in Okinawa. We examined reproductive seasonality, lunar, and circadian periodicity (based on polyp dissection, histology, and ex situ planula release observations) and larval settlement rates in the laboratory. Mesophotic S. hystrix reproduced mainly in July and early August, with a small number of planulae being released at the end of May, June and August. Compared to shallow colonies in the same region, mesophotic S. hystrix has a 4-month shorter reproductive season, similar circadian periodicity, and smaller planula size. In addition, most of the planulae settled rapidly, limiting larval dispersal potential. The shorter reproductive season and smaller planula size may result from limited energy available for reproduction at deeper depths, while the similar circadian periodicity suggests that this reproductive aspect is not affected by environmental conditions differing with depth. Overall, contribution of mesophotic S. hystrix to shallow reef rapid recovery appears limited, although they may recruit to shallow reefs through a multistep process over a few generations or through random extreme mixing such as typhoons.

Reproductive biology of the deep brooding coral Seriatopora hystrix: Implications for shallow reef recovery

PubMed Central

Prasetia, Rian; Sinniger, Frederic; Hashizume, Kaito; Harii, Saki

2017-01-01

Mesophotic coral ecosystems (MCEs, between 30 and 150 m depth) are hypothesized to contribute to the recovery of degraded shallow reefs through sexually produced larvae (referred to as Deep Reef Refuge Hypothesis). In Okinawa, Japan, the brooder coral Seriatopora hystrix was reported to be locally extinct in a shallow reef while it was found abundant at a MCE nearby. In this context, S. hystrix represents a key model to test the Deep Reef Refuge Hypothesis and to understand the potential contribution of mesophotic corals to shallow coral reef recovery. However, the reproductive biology of mesophotic S. hystrix and its potential to recolonize shallow reefs is currently unknown. This study reports for the first time, different temporal scales of reproductive periodicity and larval settlement of S. hystrix from an upper mesophotic reef (40 m depth) in Okinawa. We examined reproductive seasonality, lunar, and circadian periodicity (based on polyp dissection, histology, and ex situ planula release observations) and larval settlement rates in the laboratory. Mesophotic S. hystrix reproduced mainly in July and early August, with a small number of planulae being released at the end of May, June and August. Compared to shallow colonies in the same region, mesophotic S. hystrix has a 4-month shorter reproductive season, similar circadian periodicity, and smaller planula size. In addition, most of the planulae settled rapidly, limiting larval dispersal potential. The shorter reproductive season and smaller planula size may result from limited energy available for reproduction at deeper depths, while the similar circadian periodicity suggests that this reproductive aspect is not affected by environmental conditions differing with depth. Overall, contribution of mesophotic S. hystrix to shallow reef rapid recovery appears limited, although they may recruit to shallow reefs through a multistep process over a few generations or through random extreme mixing such as typhoons. PMID:28510601

Out of Their Depth? Isolated Deep Populations of the Cosmopolitan Coral Desmophyllum dianthus May Be Highly Vulnerable to Environmental Change

PubMed Central

Miller, Karen J.; Rowden, Ashley A.; Williams, Alan; Häussermann, Vreni

2011-01-01

Deep sea scleractinian corals will be particularly vulnerable to the effects of climate change, facing loss of up to 70% of their habitat as the Aragonite Saturation Horizon (below which corals are unable to form calcium carbonate skeletons) rises. Persistence of deep sea scleractinian corals will therefore rely on the ability of larvae to disperse to, and colonise, suitable shallow-water habitat. We used DNA sequence data of the internal transcribed spacer (ITS), the mitochondrial ribosomal subunit (16S) and mitochondrial control region (MtC) to determine levels of gene flow both within and among populations of the deep sea coral Desmophyllum dianthus in SE Australia, New Zealand and Chile to assess the ability of corals to disperse into different regions and habitats. We found significant genetic subdivision among the three widely separated geographic regions consistent with isolation and limited contemporary gene flow. Furthermore, corals from different depth strata (shallow <600 m, mid 1000–1500 m, deep >1500 m) even on the same or nearby seamounts were strongly differentiated, indicating limited vertical larval dispersal. Genetic differentiation with depth is consistent with the stratification of the Subantarctic Mode Water, Antarctic Intermediate Water, the Circumpolar Deep and North Pacific Deep Waters in the Southern Ocean, and we propose that coral larvae will be retained within, and rarely migrate among, these water masses. The apparent absence of vertical larval dispersal suggests deep populations of D. dianthus are unlikely to colonise shallow water as the aragonite saturation horizon rises and deep waters become uninhabitable. Similarly, assumptions that deep populations will act as refuges for shallow populations that are impacted by activities such as fishing or mining are also unlikely to hold true. Clearly future environmental management strategies must consider both regional and depth-related isolation of deep-sea coral populations. PMID:21611159

Ocean acidification compromises recruitment success of the threatened Caribbean coral Acropora palmata

PubMed Central

Albright, Rebecca; Mason, Benjamin; Miller, Margaret; Langdon, Chris

2010-01-01

Ocean acidification (OA) refers to the ongoing decline in oceanic pH resulting from the uptake of atmospheric CO2. Mounting experimental evidence suggests that OA will have negative consequences for a variety of marine organisms. Whereas the effect of OA on the calcification of adult reef corals is increasingly well documented, effects on early life history stages are largely unknown. Coral recruitment, which necessitates successful fertilization, larval settlement, and postsettlement growth and survivorship, is critical to the persistence and resilience of coral reefs. To determine whether OA threatens successful sexual recruitment of reef-building corals, we tested fertilization, settlement, and postsettlement growth of Acropora palmata at pCO2 levels that represent average ambient conditions during coral spawning (∼400 μatm) and the range of pCO2 increases that are expected to occur in this century [∼560 μatm (mid-CO2) and ∼800 μatm (high-CO2)]. Fertilization, settlement, and growth were all negatively impacted by increasing pCO2, and impairment of fertilization was exacerbated at lower sperm concentrations. The cumulative impact of OA on fertilization and settlement success is an estimated 52% and 73% reduction in the number of larval settlers on the reef under pCO2 conditions projected for the middle and the end of this century, respectively. Additional declines of 39% (mid-CO2) and 50% (high-CO2) were observed in postsettlement linear extension rates relative to controls. These results suggest that OA has the potential to impact multiple, sequential early life history stages, thereby severely compromising sexual recruitment and the ability of coral reefs to recover from disturbance. PMID:21059900

Ocean acidification compromises recruitment success of the threatened Caribbean coral Acropora palmata.

PubMed

Albright, Rebecca; Mason, Benjamin; Miller, Margaret; Langdon, Chris

2010-11-23

Ocean acidification (OA) refers to the ongoing decline in oceanic pH resulting from the uptake of atmospheric CO(2). Mounting experimental evidence suggests that OA will have negative consequences for a variety of marine organisms. Whereas the effect of OA on the calcification of adult reef corals is increasingly well documented, effects on early life history stages are largely unknown. Coral recruitment, which necessitates successful fertilization, larval settlement, and postsettlement growth and survivorship, is critical to the persistence and resilience of coral reefs. To determine whether OA threatens successful sexual recruitment of reef-building corals, we tested fertilization, settlement, and postsettlement growth of Acropora palmata at pCO(2) levels that represent average ambient conditions during coral spawning (∼400 μatm) and the range of pCO(2) increases that are expected to occur in this century [∼560 μatm (mid-CO(2)) and ∼800 μatm (high-CO(2))]. Fertilization, settlement, and growth were all negatively impacted by increasing pCO(2), and impairment of fertilization was exacerbated at lower sperm concentrations. The cumulative impact of OA on fertilization and settlement success is an estimated 52% and 73% reduction in the number of larval settlers on the reef under pCO(2) conditions projected for the middle and the end of this century, respectively. Additional declines of 39% (mid-CO(2)) and 50% (high-CO(2)) were observed in postsettlement linear extension rates relative to controls. These results suggest that OA has the potential to impact multiple, sequential early life history stages, thereby severely compromising sexual recruitment and the ability of coral reefs to recover from disturbance.

Developing the anemone Aiptasia as a tractable model for cnidarian-dinoflagellate symbiosis: the transcriptome of aposymbiotic A. pallida.

PubMed

Lehnert, Erik M; Burriesci, Matthew S; Pringle, John R

2012-06-22

Coral reefs are hotspots of oceanic biodiversity, forming the foundation of ecosystems that are important both ecologically and for their direct practical impacts on humans. Corals are declining globally due to a number of stressors, including rising sea-surface temperatures and pollution; such stresses can lead to a breakdown of the essential symbiotic relationship between the coral host and its endosymbiotic dinoflagellates, a process known as coral bleaching. Although the environmental stresses causing this breakdown are largely known, the cellular mechanisms of symbiosis establishment, maintenance, and breakdown are still largely obscure. Investigating the symbiosis using an experimentally tractable model organism, such as the small sea anemone Aiptasia, should improve our understanding of exactly how the environmental stressors affect coral survival and growth. We assembled the transcriptome of a clonal population of adult, aposymbiotic (dinoflagellate-free) Aiptasia pallida from ~208 million reads, yielding 58,018 contigs. We demonstrated that many of these contigs represent full-length or near-full-length transcripts that encode proteins similar to those from a diverse array of pathways in other organisms, including various metabolic enzymes, cytoskeletal proteins, and neuropeptide precursors. The contigs were annotated by sequence similarity, assigned GO terms, and scanned for conserved protein domains. We analyzed the frequency and types of single-nucleotide variants and estimated the size of the Aiptasia genome to be ~421 Mb. The contigs and annotations are available through NCBI (Transcription Shotgun Assembly database, accession numbers JV077153-JV134524) and at http://pringlelab.stanford.edu/projects.html. The availability of an extensive transcriptome assembly for A. pallida will facilitate analyses of gene-expression changes, identification of proteins of interest, and other studies in this important emerging model system.

Sensitivity of marine protected area network connectivity to atmospheric variability

NASA Astrophysics Data System (ADS)

Fox, Alan D.; Henry, Lea-Anne; Corne, David W.; Roberts, J. Murray

2016-11-01

International efforts are underway to establish well-connected systems of marine protected areas (MPAs) covering at least 10% of the ocean by 2020. But the nature and dynamics of ocean ecosystem connectivity are poorly understood, with unresolved effects of climate variability. We used 40-year runs of a particle tracking model to examine the sensitivity of an MPA network for habitat-forming cold-water corals in the northeast Atlantic to changes in larval dispersal driven by atmospheric cycles and larval behaviour. Trajectories of Lophelia pertusa larvae were strongly correlated to the North Atlantic Oscillation (NAO), the dominant pattern of interannual atmospheric circulation variability over the northeast Atlantic. Variability in trajectories significantly altered network connectivity and source-sink dynamics, with positive phase NAO conditions producing a well-connected but asymmetrical network connected from west to east. Negative phase NAO produced reduced connectivity, but notably some larvae tracked westward-flowing currents towards coral populations on the mid-Atlantic ridge. Graph theoretical metrics demonstrate critical roles played by seamounts and offshore banks in larval supply and maintaining connectivity across the network. Larval longevity and behaviour mediated dispersal and connectivity, with shorter lived and passive larvae associated with reduced connectivity. We conclude that the existing MPA network is vulnerable to atmospheric-driven changes in ocean circulation.

Seascape and life-history traits do not predict self-recruitment in a coral reef fish.

PubMed

Herrera, Marcela; Nanninga, Gerrit B; Planes, Serge; Jones, Geoffrey P; Thorrold, Simon R; Saenz-Agudelo, Pablo; Almany, Glenn R; Berumen, Michael L

2016-08-01

The persistence and resilience of many coral reef species are dependent on rates of connectivity among sub-populations. However, despite increasing research efforts, the spatial scale of larval dispersal remains unpredictable for most marine metapopulations. Here, we assess patterns of larval dispersal in the angelfish Centropyge bicolor in Kimbe Bay, Papua New Guinea, using parentage and sibling reconstruction analyses based on 23 microsatellite DNA loci. We found that, contrary to previous findings in this system, self-recruitment (SR) was virtually absent at both the reef (0.4-0.5% at 0.15 km(2)) and the lagoon scale (0.6-0.8% at approx. 700 km(2)). While approximately 25% of the collected juveniles were identified as potential siblings, the majority of sibling pairs were sampled from separate reefs. Integrating our findings with earlier research from the same system suggests that geographical setting and life-history traits alone are not suitable predictors of SR and that high levels of localized recruitment are not universal in coral reef fishes. © 2016 The Authors.

Chemically cued suppression of coral reef resilience: Where is the tipping point?

NASA Astrophysics Data System (ADS)

Brooker, Rohan M.; Hay, Mark E.; Dixson, Danielle L.

2016-12-01

Coral reefs worldwide are shifting from high-diversity, coral-dominated communities to low-diversity systems dominated by seaweeds. This shift can impact essential recovery processes such as larval recruitment and ecosystem resilience. Recent evidence suggests that chemical cues from certain corals attract, and from certain seaweeds suppress, recruitment of juvenile fishes, with loss of coral cover and increases in seaweed cover creating negative feedbacks that prevent reef recovery and sustain seaweed dominance. Unfortunately, the level of seaweed increase and coral decline that creates this chemically cued tipping point remains unknown, depriving managers of data-based targets to prevent damaging feedbacks. We conducted flume and field assays that suggest juvenile fishes sense and respond to cues produced by low levels of seaweed cover. However, the herbivore species we tested was more tolerant of degraded reef cues than non-herbivores, possibly providing some degree of resilience if these fishes recruit, consume macroalgae, and diminish negative cues.

Genes Related to Ion-Transport and Energy Production Are Upregulated in Response to CO2-Driven pH Decrease in Corals: New Insights from Transcriptome Analysis

PubMed Central

Vidal-Dupiol, Jeremie; Zoccola, Didier; Tambutté, Eric; Grunau, Christoph; Cosseau, Céline; Smith, Kristina M.; Freitag, Michael; Dheilly, Nolwenn M.; Allemand, Denis; Tambutté, Sylvie

2013-01-01

Since the preindustrial era, the average surface ocean pH has declined by 0.1 pH units and is predicted to decline by an additional 0.3 units by the year 2100. Although subtle, this decreasing pH has profound effects on the seawater saturation state of carbonate minerals and is thus predicted to impact on calcifying organisms. Among these are the scleractinian corals, which are the main builders of tropical coral reefs. Several recent studies have evaluated the physiological impact of low pH, particularly in relation to coral growth and calcification. However, very few studies have focused on the impact of low pH at the global molecular level. In this context we investigated global transcriptomic modifications in a scleractinian coral (Pocillopora damicornis) exposed to pH 7.4 compared to pH 8.1during a 3-week period. The RNAseq approach shows that 16% of our transcriptome was affected by the treatment with 6% of upregulations and 10% of downregulations. A more detailed analysis suggests that the downregulations are less coordinated than the upregulations and allowed the identification of several biological functions of interest. In order to better understand the links between these functions and the pH, transcript abundance of 48 candidate genes was quantified by q-RT-PCR (corals exposed at pH 7.2 and 7.8 for 3 weeks). The combined results of these two approaches suggest that pH≥7.4 induces an upregulation of genes coding for proteins involved in calcium and carbonate transport, conversion of CO2 into HCO3 − and organic matrix that may sustain calcification. Concomitantly, genes coding for heterotrophic and autotrophic related proteins are upregulated. This can reflect that low pH may increase the coral energy requirements, leading to an increase of energetic metabolism with the mobilization of energy reserves. In addition, the uncoordinated downregulations measured can reflect a general trade-off mechanism that may enable energy reallocation. PMID:23544045

Metamorphosis of a Scleractinian Coral in Response to Microbial Biofilms

PubMed Central

Webster, Nicole S.; Smith, Luke D.; Heyward, Andrew J.; Watts, Joy E. M.; Webb, Richard I.; Blackall, Linda L.; Negri, Andrew P.

2004-01-01

Microorganisms have been reported to induce settlement and metamorphosis in a wide range of marine invertebrate species. However, the primary cue reported for metamorphosis of coral larvae is calcareous coralline algae (CCA). Herein we report the community structure of developing coral reef biofilms and the potential role they play in triggering the metamorphosis of a scleractinian coral. Two-week-old biofilms induced metamorphosis in less than 10% of larvae, whereas metamorphosis increased significantly on older biofilms, with a maximum of 41% occurring on 8-week-old microbial films. There was a significant influence of depth in 4- and 8-week biofilms, with greater levels of metamorphosis occurring in response to shallow-water communities. Importantly, larvae were found to settle and metamorphose in response to microbial biofilms lacking CCA from both shallow and deep treatments, indicating that microorganisms not associated with CCA may play a significant role in coral metamorphosis. A polyphasic approach consisting of scanning electron microscopy, fluorescence in situ hybridization (FISH), and denaturing gradient gel electrophoresis (DGGE) revealed that coral reef biofilms were comprised of complex bacterial and microalgal communities which were distinct at each depth and time. Principal-component analysis of FISH data showed that the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Cytophaga-Flavobacterium of Bacteroidetes had the largest influence on overall community composition. A low abundance of Archaea was detected in almost all biofilms, providing the first report of Archaea associated with coral reef biofilms. No differences in the relative densities of each subdivision of Proteobacteria were observed between slides that induced larval metamorphosis and those that did not. Comparative cluster analysis of bacterial DGGE patterns also revealed that there were clear age and depth distinctions in biofilm community structure; however, no difference was detected in banding profiles between biofilms which induced larval metamorphosis and those where no metamorphosis occurred. This investigation demonstrates that complex microbial communities can induce coral metamorphosis in the absence of CCA. PMID:14766608

In vitro manipulation of gene expression in larval Schistosoma: a model for postgenomic approaches in Trematoda

PubMed Central

YOSHINO, TIMOTHY P.; DINGUIRARD, NATHALIE; DE MORAES MOURÃO, MARINA

2013-01-01

SUMMARY With rapid developments in DNA and protein sequencing technologies, combined with powerful bioinformatics tools, a continued acceleration of gene identification in parasitic helminths is predicted, potentially leading to discovery of new drug and vaccine targets, enhanced diagnostics and insights into the complex biology underlying host-parasite interactions. For the schistosome blood flukes, with the recent completion of genome sequencing and comprehensive transcriptomic datasets, there has accumulated massive amounts of gene sequence data, for which, in the vast majority of cases, little is known about actual functions within the intact organism. In this review we attempt to bring together traditional in vitro cultivation approaches and recent emergent technologies of molecular genomics, transcriptomics and genetic manipulation to illustrate the considerable progress made in our understanding of trematode gene expression and function during development of the intramolluscan larval stages. Using several prominent trematode families (Schistosomatidae, Fasciolidae, Echinostomatidae), we have focused on the current status of in vitro larval isolation/cultivation as a source of valuable raw material supporting gene discovery efforts in model digeneans that include whole genome sequencing, transcript and protein expression profiling during larval development, and progress made in the in vitro manipulation of genes and their expression in larval trematodes using transgenic and RNA interference (RNAi) approaches. PMID:19961646

The transcriptomic and evolutionary signature of social interactions regulating honey bee caste development.

USDA-ARS?s Scientific Manuscript database

The caste fate of developing female honey bee larvae is strictly socially regulated by adult nurse workers. As a result of this social regulation, nurse-expressed genes as well as larval-expressed genes may affect caste expression and evolution. We used a novel transcriptomic approach to identify ge...

Coral-zooxanthellae meta-transcriptomics reveals integrated response to pollutant stress.

PubMed

Gust, Kurt A; Najar, Fares Z; Habib, Tanwir; Lotufo, Guilherme R; Piggot, Alan M; Fouke, Bruce W; Laird, Jennifer G; Wilbanks, Mitchell S; Rawat, Arun; Indest, Karl J; Roe, Bruce A; Perkins, Edward J

2014-07-12

Corals represent symbiotic meta-organisms that require harmonization among the coral animal, photosynthetic zooxanthellae and associated microbes to survive environmental stresses. We investigated integrated-responses among coral and zooxanthellae in the scleractinian coral Acropora formosa in response to an emerging marine pollutant, the munitions constituent, 1,3,5-trinitro-1,3,5 triazine (RDX; 5 day exposures to 0 (control), 0.5, 0.9, 1.8, 3.7, and 7.2 mg/L, measured in seawater). RDX accumulated readily in coral soft tissues with bioconcentration factors ranging from 1.1 to 1.5. Next-generation sequencing of a normalized meta-transcriptomic library developed for the eukaryotic components of the A. formosa coral holobiont was leveraged to conduct microarray-based global transcript expression analysis of integrated coral/zooxanthellae responses to the RDX exposure. Total differentially expressed transcripts (DET) increased with increasing RDX exposure concentrations as did the proportion of zooxanthellae DET relative to the coral animal. Transcriptional responses in the coral demonstrated higher sensitivity to RDX compared to zooxanthellae where increased expression of gene transcripts coding xenobiotic detoxification mechanisms (i.e. cytochrome P450 and UDP glucuronosyltransferase 2 family) were initiated at the lowest exposure concentration. Increased expression of these detoxification mechanisms was sustained at higher RDX concentrations as well as production of a physical barrier to exposure through a 40% increase in mucocyte density at the maximum RDX exposure. At and above the 1.8 mg/L exposure concentration, DET coding for genes involved in central energy metabolism, including photosynthesis, glycolysis and electron-transport functions, were decreased in zooxanthellae although preliminary data indicated that zooxanthellae densities were not affected. In contrast, significantly increased transcript expression for genes involved in cellular energy production including glycolysis and electron-transport pathways was observed in the coral animal. Transcriptional network analysis for central energy metabolism demonstrated highly correlated responses to RDX among the coral animal and zooxanthellae indicative of potential compensatory responses to lost photosynthetic potential within the holobiont. These observations underscore the potential for complex integrated responses to RDX exposure among species comprising the coral holobiont and highlight the need to understand holobiont-species interactions to accurately assess pollutant impacts.

Identification of MicroRNAs in the Coral Stylophora pistillata

PubMed Central

Liew, Yi Jin; Aranda, Manuel; Carr, Adrian; Baumgarten, Sebastian; Zoccola, Didier; Tambutté, Sylvie; Allemand, Denis; Micklem, Gos; Voolstra, Christian R.

2014-01-01

Coral reefs are major contributors to marine biodiversity. However, they are in rapid decline due to global environmental changes such as rising sea surface temperatures, ocean acidification, and pollution. Genomic and transcriptomic analyses have broadened our understanding of coral biology, but a study of the microRNA (miRNA) repertoire of corals is missing. miRNAs constitute a class of small non-coding RNAs of ∼22 nt in size that play crucial roles in development, metabolism, and stress response in plants and animals alike. In this study, we examined the coral Stylophora pistillata for the presence of miRNAs and the corresponding core protein machinery required for their processing and function. Based on small RNA sequencing, we present evidence for 31 bona fide microRNAs, 5 of which (miR-100, miR-2022, miR-2023, miR-2030, and miR-2036) are conserved in other metazoans. Homologues of Argonaute, Piwi, Dicer, Drosha, Pasha, and HEN1 were identified in the transcriptome of S. pistillata based on strong sequence conservation with known RNAi proteins, with additional support derived from phylogenetic trees. Examination of putative miRNA gene targets indicates potential roles in development, metabolism, immunity, and biomineralisation for several of the microRNAs. Here, we present first evidence of a functional RNAi machinery and five conserved miRNAs in S. pistillata, implying that miRNAs play a role in organismal biology of scleractinian corals. Analysis of predicted miRNA target genes in S. pistillata suggests potential roles of miRNAs in symbiosis and coral calcification. Given the importance of miRNAs in regulating gene expression in other metazoans, further expression analyses of small non-coding RNAs in transcriptional studies of corals should be informative about miRNA-affected processes and pathways. PMID:24658574

Rapid Acclimation Ability Mediated by Transcriptome Changes in Reef-Building Corals.

PubMed

Bay, Rachael A; Palumbi, Stephen R

2015-05-15

Population response to environmental variation involves adaptation, acclimation, or both. For long-lived organisms, acclimation likely generates a faster response but is only effective if the rates and limits of acclimation match the dynamics of local environmental variation. In coral reef habitats, heat stress from extreme ocean warming can occur over several weeks, resulting in symbiont expulsion and widespread coral death. However, transcriptome regulation during short-term acclimation is not well understood. We examined acclimation during a 11-day experiment in the coral Acropora nana. We acclimated colonies to three regimes: ambient temperature (29 °C), increased stable temperature (31 °C), and variable temperature (29-33 °C), mimicking local heat stress conditions. Within 7-11 days, individuals acclimated to increased temperatures had higher tolerance to acute heat stress. Despite physiological changes, no gene expression changes occurred during acclimation before acute heat stress. However, we found strikingly different transcriptional responses to heat stress between acclimation treatments across 893 contigs. Across these contigs, corals acclimated to higher temperatures (31 °C or 29-33 °C) exhibited a muted stress response--the magnitude of expression change before and after heat stress was less than in 29 °C acclimated corals. Our results show that corals have a rapid phase of acclimation that substantially increases their heat resilience within 7 days and that alters their transcriptional response to heat stress. This is in addition to a previously observed longer term response, distinguishable by its shift in baseline expression, under nonstressful conditions. Such rapid acclimation may provide some protection for this species of coral against slow onset of warming ocean temperatures. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Rapid Acclimation Ability Mediated by Transcriptome Changes in Reef-Building Corals

PubMed Central

Bay, Rachael A.; Palumbi, Stephen R.

2015-01-01

Population response to environmental variation involves adaptation, acclimation, or both. For long-lived organisms, acclimation likely generates a faster response but is only effective if the rates and limits of acclimation match the dynamics of local environmental variation. In coral reef habitats, heat stress from extreme ocean warming can occur over several weeks, resulting in symbiont expulsion and widespread coral death. However, transcriptome regulation during short-term acclimation is not well understood. We examined acclimation during a 11-day experiment in the coral Acropora nana. We acclimated colonies to three regimes: ambient temperature (29 °C), increased stable temperature (31 °C), and variable temperature (29–33 °C), mimicking local heat stress conditions. Within 7–11 days, individuals acclimated to increased temperatures had higher tolerance to acute heat stress. Despite physiological changes, no gene expression changes occurred during acclimation before acute heat stress. However, we found strikingly different transcriptional responses to heat stress between acclimation treatments across 893 contigs. Across these contigs, corals acclimated to higher temperatures (31 °C or 29–33 °C) exhibited a muted stress response—the magnitude of expression change before and after heat stress was less than in 29 °C acclimated corals. Our results show that corals have a rapid phase of acclimation that substantially increases their heat resilience within 7 days and that alters their transcriptional response to heat stress. This is in addition to a previously observed longer term response, distinguishable by its shift in baseline expression, under nonstressful conditions. Such rapid acclimation may provide some protection for this species of coral against slow onset of warming ocean temperatures. PMID:25979751

Impact of a novel protein meal on the gastrointestinal microbiota and the host transcriptome of larval zebrafish Danio rerio

PubMed Central

Rurangwa, Eugene; Sipkema, Detmer; Kals, Jeroen; ter Veld, Menno; Forlenza, Maria; Bacanu, Gianina M.; Smidt, Hauke; Palstra, Arjan P.

2015-01-01

Larval zebrafish was subjected to a methodological exploration of the gastrointestinal microbiota and transcriptome. Assessed was the impact of two dietary inclusion levels of a novel protein meal (NPM) of animal origin (ragworm Nereis virens) on the gastrointestinal tract (GIT). Microbial development was assessed over the first 21 days post egg fertilization (dpf) through 16S rRNA gene-based microbial composition profiling by pyrosequencing. Differentially expressed genes in the GIT were demonstrated at 21 dpf by whole transcriptome sequencing (mRNAseq). Larval zebrafish showed rapid temporal changes in microbial colonization but domination occurred by one to three bacterial species generally belonging to Proteobacteria and Firmicutes. The high iron content of NPM may have led to an increased relative abundance of bacteria that were related to potential pathogens and bacteria with an increased iron metabolism. Functional classification of the 328 differentially expressed genes indicated that the GIT of larvae fed at higher NPM level was more active in transmembrane ion transport and protein synthesis. mRNAseq analysis did not reveal a major activation of genes involved in the immune response or indicating differences in iron uptake and homeostasis in zebrafish fed at the high inclusion level of NPM. PMID:25983694

Transcriptomic differences between day and night in Acropora millepora provide new insights into metabolite exchange and light-enhanced calcification in corals.

PubMed

Bertucci, A; Forêt, S; Ball, E E; Miller, D J

2015-09-01

The evolutionary success of reef-building corals is often attributed to their symbiotic relationship with photosynthetic dinoflagellates of the genus Symbiodinium, but metabolic interactions between the partners and the molecular bases of light-enhanced calcification (LEC) are not well understood. Here, the metabolic bases of the interaction between the coral Acropora millepora and its dinoflagellate symbiont were investigated by comparing gene expression levels under light and dark conditions at the whole transcriptome level. Among the 497 differentially expressed genes identified, a suite of genes involved in cholesterol transport was found to be upregulated under light conditions, confirming the significance of this compound in the coral symbiosis. Although ion transporters likely to have roles in calcification were not differentially expressed in this study, expression levels of many genes associated with skeletal organic matrix composition and organization were higher in light conditions. This implies that the rate of organic matrix synthesis is one factor limiting calcification at night. Thus, LEC during the day is likely to be a consequence of increases in both matrix synthesis and the supply of precursor molecules as a result of photosynthetic activity. © 2015 John Wiley & Sons Ltd.

Reef scent: How brooded coral larvae from a tough coral smell their way to a new home

NASA Astrophysics Data System (ADS)

Spies, N.; Richmond, R. H.; Seneca, F.; Murphy, J.; Martinez, J.; Lyman, A.

2016-02-01

Coral reefs are highly diverse marine ecosystems of ecological, economic, and cultural value. With the expected negative effects on reefs from global climate change including rising sea temperatures and ocean acidification, the identification of resilient coral species has become increasingly important. Leptastrea purpurea is an encrusting coral that is found throughout the Indo-Pacific and Red Sea. While most corals are broadcast spawners, releasing sperm and eggs to be fertilized in the water column, some corals brood embryos within their tissues after internal fertilization. L. purpurea appears to release planula larvae on a continuous basis from the parent colony as observed during two years of monitoring. The planula larvae show remarkable resilience under a wide range of stressful conditions including temperature, sediment, and chemical stressors, as well as the ability to successfully settle and metamorphose after 180 days in controlled laboratory conditions. Various smells were tested to identify a settlement cue for L. purpurea larvae, and our results suggest that the smell associated with other coral colonies induce larval settlement and metamorphosis. Knowledge of the settlement cues and reproductive biology of this coral is important to our understanding of coral resilience in the face of anthropogenic perturbation.

Tissue-Specific Transcriptome Profiling of Plutella Xylostella Third Instar Larval Midgut

PubMed Central

Xie, Wen; Lei, Yanyuan; Fu, Wei; Yang, Zhongxia; Zhu, Xun; Guo, Zhaojiang; Wu, Qingjun; Wang, Shaoli; Xu, Baoyun; Zhou, Xuguo; Zhang, Youjun

2012-01-01

The larval midgut of diamondback moth, Plutella xylostella, is a dynamic tissue that interfaces with a diverse array of physiological and toxicological processes, including nutrient digestion and allocation, xenobiotic detoxification, innate and adaptive immune response, and pathogen defense. Despite its enormous agricultural importance, the genomic resources for P. xylostella are surprisingly scarce. In this study, a Bt resistant P. xylostella strain was subjected to the in-depth transcriptome analysis to identify genes and gene networks putatively involved in various physiological and toxicological processes in the P. xylostella larval midgut. Using Illumina deep sequencing, we obtained roughly 40 million reads containing approximately 3.6 gigabases of sequence data. De novo assembly generated 63,312 ESTs with an average read length of 416bp, and approximately half of the P. xylostella sequences (45.4%, 28,768) showed similarity to the non-redundant database in GenBank with a cut-off E-value below 10-5. Among them, 11,092 unigenes were assigned to one or multiple GO terms and 16,732 unigenes were assigned to 226 specific pathways. In-depth analysis indentified genes putatively involved in insecticide resistance, nutrient digestion, and innate immune defense. Besides conventional detoxification enzymes and insecticide targets, novel genes, including 28 chymotrypsins and 53 ABC transporters, have been uncovered in the P. xylostella larval midgut transcriptome; which are potentially linked to the Bt toxicity and resistance. Furthermore, an unexpectedly high number of ESTs, including 46 serpins and 7 lysozymes, were predicted to be involved in the immune defense. As the first tissue-specific transcriptome analysis of P. xylostella, this study sheds light on the molecular understanding of insecticide resistance, especially Bt resistance in an agriculturally important insect pest, and lays the foundation for future functional genomics research. In addition, current sequencing effort greatly enriched the existing P. xylostella EST database, and makes RNAseq a viable option in the future genomic analysis. PMID:23091412

Tissue-specific transcriptome profiling of Plutella xylostella third instar larval midgut.

PubMed

Xie, Wen; Lei, Yanyuan; Fu, Wei; Yang, Zhongxia; Zhu, Xun; Guo, Zhaojiang; Wu, Qingjun; Wang, Shaoli; Xu, Baoyun; Zhou, Xuguo; Zhang, Youjun

2012-01-01

The larval midgut of diamondback moth, Plutella xylostella, is a dynamic tissue that interfaces with a diverse array of physiological and toxicological processes, including nutrient digestion and allocation, xenobiotic detoxification, innate and adaptive immune response, and pathogen defense. Despite its enormous agricultural importance, the genomic resources for P. xylostella are surprisingly scarce. In this study, a Bt resistant P. xylostella strain was subjected to the in-depth transcriptome analysis to identify genes and gene networks putatively involved in various physiological and toxicological processes in the P. xylostella larval midgut. Using Illumina deep sequencing, we obtained roughly 40 million reads containing approximately 3.6 gigabases of sequence data. De novo assembly generated 63,312 ESTs with an average read length of 416 bp, and approximately half of the P. xylostella sequences (45.4%, 28,768) showed similarity to the non-redundant database in GenBank with a cut-off E-value below 10(-5). Among them, 11,092 unigenes were assigned to one or multiple GO terms and 16,732 unigenes were assigned to 226 specific pathways. In-depth analysis identified genes putatively involved in insecticide resistance, nutrient digestion, and innate immune defense. Besides conventional detoxification enzymes and insecticide targets, novel genes, including 28 chymotrypsins and 53 ABC transporters, have been uncovered in the P. xylostella larval midgut transcriptome; which are potentially linked to the Bt toxicity and resistance. Furthermore, an unexpectedly high number of ESTs, including 46 serpins and 7 lysozymes, were predicted to be involved in the immune defense.As the first tissue-specific transcriptome analysis of P. xylostella, this study sheds light on the molecular understanding of insecticide resistance, especially Bt resistance in an agriculturally important insect pest, and lays the foundation for future functional genomics research. In addition, current sequencing effort greatly enriched the existing P. xylostella EST database, and makes RNAseq a viable option in the future genomic analysis.

Immune response of the Caribbean sea fan, Gorgonia ventalina, exposed to an Aplanochytrium parasite as revealed by transcriptome sequencing

PubMed Central

Burge, Colleen A.; Mouchka, Morgan E.; Harvell, C. Drew; Roberts, Steven

2013-01-01

Coral reef communities are undergoing marked declines due to a variety of stressors including disease. The sea fan coral, Gorgonia ventalina, is a tractable study system to investigate mechanisms of immunity to a naturally occurring pathogen. Functional studies in Gorgonia ventalina immunity indicate that several key pathways and cellular components are involved in response to natural microbial invaders, although to date the functional and regulatory pathways remain largely un-described. This study used short-read sequencing (Illumina GAIIx) to identify genes involved in the response of G. ventalina to a naturally occurring Aplanochytrium spp. parasite. De novo assembly of the G. ventalina transcriptome yielded 90,230 contigs of which 40,142 were annotated. RNA-Seq analysis revealed 210 differentially expressed genes in sea fans exposed to the Aplanochytrium parasite. Differentially expressed genes involved in immunity include pattern recognition molecules, anti-microbial peptides, and genes involved in wound repair and reactive oxygen species formation. Gene enrichment analysis indicated eight biological processes were enriched representing 36 genes, largely involved with protein translation and energy production. This is the first report using high-throughput sequencing to characterize the host response of a coral to a natural pathogen. Furthermore, we have generated the first transcriptome for a soft (octocoral or non-scleractinian) coral species. Expression analysis revealed genes important in invertebrate innate immune pathways, as well as those whose role is previously un-described in cnidarians. This resource will be valuable in characterizing G. ventalina immune response to infection and co-infection of pathogens in the context of environmental change. PMID:23898300

High tolerance to temperature and salinity change should enable scleractinian coral Platygyra acuta from marginal environments to persist under future climate change.

PubMed

Chui, Apple Pui Yi; Ang, Put

2017-01-01

With projected changes in the marine environment under global climate change, the effects of single stressors on corals have been relatively well studied. However, more focus should be placed on the interactive effects of multiple stressors if their impacts upon corals are to be assessed more realistically. Elevation of sea surface temperature is projected under global climate change, and future increases in precipitation extremes related to the monsoon are also expected. Thus, the lowering of salinity could become a more common phenomenon and its impact on corals could be significant as extreme precipitation usually occurs during the coral spawning season. Here, we investigated the interactive effects of temperature [24, 27 (ambient), 30, 32°C] and salinity [33 psu (ambient), 30, 26, 22, 18, 14 psu] on larval settlement, post-settlement survival and early growth of the dominant coral Platygyra acuta from Hong Kong, a marginal environment for coral growth. The results indicate that elevated temperatures (+3°C and +5°C above ambient) did not have any significant effects on larval settlement success and post-settlement survival for up to 56 days of prolonged exposure. Such thermal tolerance was markedly higher than that reported in the literature for other coral species. Moreover, there was a positive effect of these elevated temperatures in reducing the negative effects of lowered salinity (26 psu) on settlement success. The enhanced settlement success brought about by elevated temperatures, together with the high post-settlement survival recorded up to 44 and 8 days of exposure under +3°C and +5°C ambient respectively, resulted in the overall positive effects of elevated temperatures on recruitment success. These results suggest that projected elevation in temperature over the next century should not pose any major problem for the recruitment success of P. acuta. The combined effects of higher temperatures and lowered salinity (26 psu) could even be beneficial. Therefore, corals that are currently present in marginal environments like Hong Kong, as exemplified by the dominant P. acuta, are likely to persist in a warmer and intermittently less saline, future ocean.

High tolerance to temperature and salinity change should enable scleractinian coral Platygyra acuta from marginal environments to persist under future climate change

PubMed Central

Chui, Apple Pui Yi; Ang, Put

2017-01-01

With projected changes in the marine environment under global climate change, the effects of single stressors on corals have been relatively well studied. However, more focus should be placed on the interactive effects of multiple stressors if their impacts upon corals are to be assessed more realistically. Elevation of sea surface temperature is projected under global climate change, and future increases in precipitation extremes related to the monsoon are also expected. Thus, the lowering of salinity could become a more common phenomenon and its impact on corals could be significant as extreme precipitation usually occurs during the coral spawning season. Here, we investigated the interactive effects of temperature [24, 27 (ambient), 30, 32°C] and salinity [33 psu (ambient), 30, 26, 22, 18, 14 psu] on larval settlement, post-settlement survival and early growth of the dominant coral Platygyra acuta from Hong Kong, a marginal environment for coral growth. The results indicate that elevated temperatures (+3°C and +5°C above ambient) did not have any significant effects on larval settlement success and post-settlement survival for up to 56 days of prolonged exposure. Such thermal tolerance was markedly higher than that reported in the literature for other coral species. Moreover, there was a positive effect of these elevated temperatures in reducing the negative effects of lowered salinity (26 psu) on settlement success. The enhanced settlement success brought about by elevated temperatures, together with the high post-settlement survival recorded up to 44 and 8 days of exposure under +3°C and +5°C ambient respectively, resulted in the overall positive effects of elevated temperatures on recruitment success. These results suggest that projected elevation in temperature over the next century should not pose any major problem for the recruitment success of P. acuta. The combined effects of higher temperatures and lowered salinity (26 psu) could even be beneficial. Therefore, corals that are currently present in marginal environments like Hong Kong, as exemplified by the dominant P. acuta, are likely to persist in a warmer and intermittently less saline, future ocean. PMID:28622371

Reproductive ecology and early life history traits of the brooding coral, Porites astreoides, from shallow to mesophotic zones

NASA Astrophysics Data System (ADS)

Goodbody-Gringley, Gretchen; Wong, Kevin H.; Becker, Danielle M.; Glennon, Keegan; de Putron, Samantha J.

2018-06-01

Early life history traits of brooding corals are often affected by the environmental conditions experienced by parental colonies. Such parental effects can impact offspring survival, which influences the overall success of a population as well as resilience to environmental challenges. This study examines the reproductive ecology and early life history traits of the brooding coral Porites astreoides across a depth gradient in Bermuda. Fecundity, larval size, larval Symbiodinium density, and settlement success, as well as post-metamorphic juvenile survival, growth, and Symbiodinium density were compared across three reef sites representing an inshore patch reef (2-5 m), an offshore rim reef (8-10 m), and an upper-mesophotic reef (30-33 m). Although fecundity did not differ across sites, larvae produced by colonies on the patch reef site were smaller, had lower Symbiodinium densities, and had lower rates of settlement and juvenile survival compared to larvae from colonies on the rim and upper-mesophotic reef sites. Larvae produced by colonies from the rim and upper-mesophotic sites did not differ in size or Symbiodinium densities; however, rates of settlement, growth, and survival were higher for larvae from the upper-mesophotic site compared to those from the rim reef site. These results indicate that offspring quality and success vary among sites with differing environmental conditions and may imply higher recruitment potential and resilience for upper-mesophotic corals.

Strategies and trajectories of coral reef fish larvae optimizing self-recruitment.

PubMed

Irisson, Jean-Olivier; LeVan, Anselme; De Lara, Michel; Planes, Serge

2004-03-21

Like many marine organisms, most coral reef fishes have a dispersive larval phase. The fate of this phase is of great concern for their ecology as it may determine population demography and connectivity. As direct study of the larval phase is difficult, we tackle the question of dispersion from an opposite point of view and study self-recruitment. In this paper, we propose a mathematical model of the pelagic phase, parameterized by a limited number of factors (currents, predator and prey distributions, energy budgets) and which focuses on the behavioral response of the larvae to these factors. We evaluate optimal behavioral strategies of the larvae (i.e. strategies that maximize the probability of return to the natal reef) and examine the trajectories of dispersal that they induce. Mathematically, larval behavior is described by a controlled Markov process. A strategy induces a sequence, indexed by time steps, of "decisions" (e.g. looking for food, swimming in a given direction). Biological, physical and topographic constraints are captured through the transition probabilities and the sets of possible decisions. Optimal strategies are found by means of the so-called stochastic dynamic programming equation. A computer program is developed and optimal decisions and trajectories are numerically derived. We conclude that this technique can be considered as a good tool to represent plausible larval behaviors and that it has great potential in terms of theoretical investigations and also for field applications.

Toxicity of Deepwater Horizon Source Oil and the Chemical Dispersant, Corexit® 9500, to Coral Larvae

PubMed Central

Goodbody-Gringley, Gretchen; Wetzel, Dana L.; Gillon, Daniel; Pulster, Erin; Miller, Allison; Ritchie, Kim B.

2013-01-01

Acute catastrophic events can cause significant damage to marine environments in a short time period and may have devastating long-term impacts. In April 2010 the BP-operated Deepwater Horizon (DWH) offshore oil rig exploded, releasing an estimated 760 million liters of crude oil into the Gulf of Mexico. This study examines the potential effects of oil spill exposure on coral larvae of the Florida Keys. Larvae of the brooding coral, Porites astreoides, and the broadcast spawning coral, Montastraea faveolata, were exposed to multiple concentrations of BP Horizon source oil (crude, weathered and WAF), oil in combination with the dispersant Corexit® 9500 (CEWAF), and dispersant alone, and analyzed for behavior, settlement, and survival. Settlement and survival of P. astreoides and M. faveolata larvae decreased with increasing concentrations of WAF, CEWAF and Corexit® 9500, however the degree of the response varied by species and solution. P. astreoides larvae experienced decreased settlement and survival following exposure to 0.62 ppm source oil, while M. faveolata larvae were negatively impacted by 0.65, 1.34 and 1.5 ppm, suggesting that P. astreoides larvae may be more tolerant to WAF exposure than M. faveolata larvae. Exposure to medium and high concentrations of CEWAF (4.28/18.56 and 30.99/35.76 ppm) and dispersant Corexit® 9500 (50 and 100 ppm), significantly decreased larval settlement and survival for both species. Furthermore, exposure to Corexit® 9500 resulted in settlement failure and complete larval mortality after exposure to 50 and 100 ppm for M. faveolata and 100 ppm for P. astreoides. These results indicate that exposure of coral larvae to oil spill related contaminants, particularly the dispersant Corexit® 9500, has the potential to negatively impact coral settlement and survival, thereby affecting the resilience and recovery of coral reefs following exposure to oil and dispersants. PMID:23326298

Exploring the larval fish community of the central Red Sea with an integrated morphological and molecular approach.

PubMed

Isari, Stamatina; Pearman, John K; Casas, Laura; Michell, Craig T; Curdia, Joao; Berumen, Michael L; Irigoien, Xabier

2017-01-01

An important aspect of population dynamics for coral reef fishes is the input of new individuals from the pelagic larval pool. However, the high biodiversity and the difficulty of identifying larvae of closely related species represent obstacles to more fully understanding these populations. In this study, we combined morphology and genetic barcoding (Cytochrome Oxidase I gene) to characterize the seasonal patterns of the larval fish community at two sites in close proximity to coral reefs in the central-north Red Sea: one shallower inshore location (50 m depth) and a nearby site located in deeper and more offshore waters (~ 500 m depth). Fish larvae were collected using oblique tows of a 60 cm-bongo net (500 μm mesh size) every month for one year (2013). During the warmer period of the year (June-November), the larval fish stock was comparable between sampling sites. However, during the colder months, abundances were higher in the inshore than in the offshore waters. Taxonomic composition and temporal variation of community structure differed notably between sites, potentially reflecting habitat differences, reproductive patterns of adults, and/or advective processes in the area. Eleven out of a total of 62 recorded families comprised 69-94% of the fish larval community, depending on sampling site and month. Richness of taxa was notably higher in the inshore station compared to the offshore, particularly during the colder period of the year and especially for the gobiids and apogonids. Two mesopelagic taxa (Vinciguerria sp. and Benthosema spp.) comprised an important component of the larval community at the deeper site with only a small and sporadic occurrence in the shallower inshore waters. Our data provide an important baseline reference for the larval fish communities of the central Red Sea, representing the first such study from Saudi Arabian waters.

Exploring the larval fish community of the central Red Sea with an integrated morphological and molecular approach

PubMed Central

Pearman, John K.; Casas, Laura; Michell, Craig T.; Curdia, Joao; Berumen, Michael L.; Irigoien, Xabier

2017-01-01

An important aspect of population dynamics for coral reef fishes is the input of new individuals from the pelagic larval pool. However, the high biodiversity and the difficulty of identifying larvae of closely related species represent obstacles to more fully understanding these populations. In this study, we combined morphology and genetic barcoding (Cytochrome Oxidase I gene) to characterize the seasonal patterns of the larval fish community at two sites in close proximity to coral reefs in the central-north Red Sea: one shallower inshore location (50 m depth) and a nearby site located in deeper and more offshore waters (~ 500 m depth). Fish larvae were collected using oblique tows of a 60 cm-bongo net (500 μm mesh size) every month for one year (2013). During the warmer period of the year (June-November), the larval fish stock was comparable between sampling sites. However, during the colder months, abundances were higher in the inshore than in the offshore waters. Taxonomic composition and temporal variation of community structure differed notably between sites, potentially reflecting habitat differences, reproductive patterns of adults, and/or advective processes in the area. Eleven out of a total of 62 recorded families comprised 69–94% of the fish larval community, depending on sampling site and month. Richness of taxa was notably higher in the inshore station compared to the offshore, particularly during the colder period of the year and especially for the gobiids and apogonids. Two mesopelagic taxa (Vinciguerria sp. and Benthosema spp.) comprised an important component of the larval community at the deeper site with only a small and sporadic occurrence in the shallower inshore waters. Our data provide an important baseline reference for the larval fish communities of the central Red Sea, representing the first such study from Saudi Arabian waters. PMID:28771590

The effects of parasites on the early life stages of a damselfish

NASA Astrophysics Data System (ADS)

Sun, D.; Blomberg, S. P.; Cribb, T. H.; McCormick, M. I.; Grutter, A. S.

2012-12-01

Early life history traits, such as larval growth, influence the success of coral reef fish in the transition from the larval to the juvenile life phase. Few studies, however, have examined the relationship between parasites and growth in the early life history stages of such fishes. This study examined how parasite prevalence (% infected) and load, and the relationship between parasite presence and fish growth, differed among life stages of the damselfish Pomacentrus amboinensis. Parasite prevalence decreased significantly between the larval stage, which was sampled immediately before settlement on the reef (97 %) and recently settled juveniles (60 %); prevalence was also high for 4-month-old juveniles (90 %), 7-month-old juveniles (100 %) and adult fish (100 %). Total numbers of parasites per fish decreased dramatically (fourfold) between larval and recently settled fish, and then increased in the older stages to levels similar to those observed in larvae, but they did so more gradually than did prevalence. One explanation for these patterns is that heavily infected larvae were preferentially removed from the population during or soon after settlement. Daily fish growth, determined from otolith increments, revealed that growth did not differ between parasitised and non-parasitised larval fish, whereas recently settled fish that were parasitised had faster growth; these parasitised recently settled fish also displayed faster growth prior to settlement. These data provide evidence that parasites may explain some of the variation in growth and survival observed among coral reef fishes after settlement and thereby have a greater impact on population dynamics than previously understood.

Narrower grid structure of artificial reef enhances initial survival of in situ settled coral.

PubMed

Suzuki, Go; Kai, Sayaka; Yamashita, Hiroshi; Suzuki, Kiyoshi; Iehisa, Yukihiro; Hayashibara, Takeshi

2011-12-01

The initial factors that cause a decline in the survival of in situ settled corals remain poorly understood. In this study, we demonstrated through field experiments that the design of artificial grid plates may influence the initial survival of Acropora corals, with narrower grids being the most effective. In fact, grid plates with a 2.5-cm mesh presented the highest recorded survival rate (14%) at 6 months after settlement (representing approximately 50 corals per 0.25 m(2) of plate). This is the first study where such high survival rates, matching those of cultures under aquarium conditions, were obtained in the field without using additional protective measures, such as guard nets against fish grazing after seeding. Therefore, our results provide a foundation for establishing new and effective coral restoration techniques for larval seeding, in parallel to clarifying the details of the early life stages of reef-building corals. Copyright © 2011 Elsevier Ltd. All rights reserved.

Larval dispersal in three coral reef decapod species: Influence of larval duration on the metapopulation structure.

PubMed

Sanvicente-Añorve, Laura; Zavala-Hidalgo, Jorge; Allende-Arandía, Eugenia; Hermoso-Salazar, Margarita

2018-01-01

Most coral-associated decapod species have non-migratory adult populations and depend on their planktonic larvae for dispersal. This study examined the metapopulation structure of three decapod species with different pelagic larval duration (PLD) from twelve coral reef complexes of the Gulf of Mexico. The dispersion of larvae was analyzed through the use of a realistic numerical simulation of the Gulf of Mexico with the Hybrid Coordinate Ocean Model. To study the transport and dispersion of particles in near-surface waters, a particle-tracking subroutine was run using as input the currents from the model. The simulation consisted of the launch of 100 passive particles (virtual larvae) every 24 hours from each reef throughout five years, and tracked for as long as 210 days. Results indicated that species with a short PLD, Mithraculus sculptus (PLD 8‒13 days), had a weak connection among the reefs, but higher self-recruitment, especially on the narrow western shelf. The species with a longer PLD, Dromia erythropus (28‒30 days), had a stronger connection among neighboring reefs (< 300 km). Finally, the species with an even longer PLD, Stenopus hispidus (123‒210 days), had a wider potential distribution than the other species. Circulation on synoptic, seasonal and interannual scales had differential effects on the larval dispersal of each species. The metapopulation structure of M. sculptus and D. erythropus seemed to combine features of the non-equilibrium and the patchy models, whereas that of S. hispidus presumably fit to a patchy model. These findings support previous observations that indicate that species with longer PLD tend to occupy larger areas than species with short PLD, although recruitment of juveniles to the adult populations will also depend on other factors, such as the availability of suitable habitats and the ability to colonize them.

Larval dispersal in three coral reef decapod species: Influence of larval duration on the metapopulation structure

PubMed Central

Zavala-Hidalgo, Jorge; Allende-Arandía, Eugenia; Hermoso-Salazar, Margarita

2018-01-01

Most coral-associated decapod species have non-migratory adult populations and depend on their planktonic larvae for dispersal. This study examined the metapopulation structure of three decapod species with different pelagic larval duration (PLD) from twelve coral reef complexes of the Gulf of Mexico. The dispersion of larvae was analyzed through the use of a realistic numerical simulation of the Gulf of Mexico with the Hybrid Coordinate Ocean Model. To study the transport and dispersion of particles in near-surface waters, a particle-tracking subroutine was run using as input the currents from the model. The simulation consisted of the launch of 100 passive particles (virtual larvae) every 24 hours from each reef throughout five years, and tracked for as long as 210 days. Results indicated that species with a short PLD, Mithraculus sculptus (PLD 8‒13 days), had a weak connection among the reefs, but higher self-recruitment, especially on the narrow western shelf. The species with a longer PLD, Dromia erythropus (28‒30 days), had a stronger connection among neighboring reefs (< 300 km). Finally, the species with an even longer PLD, Stenopus hispidus (123‒210 days), had a wider potential distribution than the other species. Circulation on synoptic, seasonal and interannual scales had differential effects on the larval dispersal of each species. The metapopulation structure of M. sculptus and D. erythropus seemed to combine features of the non-equilibrium and the patchy models, whereas that of S. hispidus presumably fit to a patchy model. These findings support previous observations that indicate that species with longer PLD tend to occupy larger areas than species with short PLD, although recruitment of juveniles to the adult populations will also depend on other factors, such as the availability of suitable habitats and the ability to colonize them. PMID:29558478

Systemic response of the stony coral Pocillopora damicornis against acute cadmium stress.

PubMed

Zhou, Zhi; Yu, Xiaopeng; Tang, Jia; Wu, Yibo; Wang, Lingui; Huang, Bo

2018-01-01

Heavy metals have become one of the main pollutants in the marine environment and a major threat to the growth and reproduction of stony corals. In the present study, the density of symbiotic zooxanthellae, levels of crucial physiological activities and the transcriptome were investigated in the stony coral Pocillopora damicornis after the acute exposure to elevated cadmium concentration. The density of symbiotic zooxanthellae decreased significantly during 12-24h period, and reached lowest at 24h after acute cadmium stress. No significant changes were observed in the activity of glutathione S-transferase during the entire stress exposure. The activities of superoxide dismutase and catalase, and the concentration of glutathione decreased significantly, but the activation level of caspase3 increased significantly after cadmium exposure. Furthermore, transcriptome sequencing and bioinformatics analysis revealed 3538 significantly upregulated genes and 8048 significantly downregulated genes at 12h after the treatment. There were 12 overrepresented GO terms for significantly upregulated genes, mostly related to unfolded protein response, endoplasmic reticulum stress and apoptosis. In addition, a total of 32 GO terms were overrepresented for significantly downregulated genes, and mainly correlated with macromolecular metabolic processes. These results collectively suggest that acute cadmium stress could induce apoptosis by repressing the production of the antioxidants, elevating oxidative stress and activating the unfolded protein response. This cascade of reactions would result to the collapse of the coral-zooxanthella symbiosis and the expulsion of symbiotic zooxanthellae in the stony coral P. damicornis, ultimately leading to coral bleaching. Copyright © 2017 Elsevier B.V. All rights reserved.

Functional genomics identifies regulators of the phototransduction machinery in the Drosophila larval eye and adult ocelli.

PubMed

Mishra, Abhishek Kumar; Bargmann, Bastiaan O R; Tsachaki, Maria; Fritsch, Cornelia; Sprecher, Simon G

2016-02-15

Sensory perception of light is mediated by specialized Photoreceptor neurons (PRs) in the eye. During development all PRs are genetically determined to express a specific Rhodopsin (Rh) gene and genes mediating a functional phototransduction pathway. While the genetic and molecular mechanisms of PR development is well described in the adult compound eye, it remains unclear how the expression of Rhodopsins and the phototransduction cascade is regulated in other visual organs in Drosophila, such as the larval eye and adult ocelli. Using transcriptome analysis of larval PR-subtypes and ocellar PRs we identify and study new regulators required during PR differentiation or necessary for the expression of specific signaling molecules of the functional phototransduction pathway. We found that the transcription factor Krüppel (Kr) is enriched in the larval eye and controls PR differentiation by promoting Rh5 and Rh6 expression. We also identified Camta, Lola, Dve and Hazy as key genes acting during ocellar PR differentiation. Further we show that these transcriptional regulators control gene expression of the phototransduction cascade in both larval eye and adult ocelli. Our results show that PR cell type-specific transcriptome profiling is a powerful tool to identify key transcriptional regulators involved during several aspects of PR development and differentiation. Our findings greatly contribute to the understanding of how combinatorial action of key transcriptional regulators control PR development and the regulation of a functional phototransduction pathway in both larval eye and adult ocelli. Copyright © 2015 Elsevier Inc. All rights reserved.

Inhibition of coral recruitment by macroalgae and cyanobacteria

USGS Publications Warehouse

Kuffner, I.B.; Walters, L.J.; Becerro, M.A.; Paul, V.J.; Ritson-Williams, R.; Beach, K.S.

2006-01-01

Coral recruitment is a key process in the maintenance and recovery of coral reef ecosystems. While intense competition between coral and algae is often assumed on reefs that have undergone phase shifts from coral to algal dominance, data examining the competitive interactions involved, particularly during the larval and immediate post-settlement stage, are scarce. Using a series of field and outdoor seawater table experiments, we tested the hypothesis that common species of macroalgae and cyanobacteria inhibit coral recruitment. We examined the effects of Lyngbya spp., Dictyota spp., Lobophora variegata (J. V. Lamouroux) Womersley, and Chondrophycus poiteaui (J. V. Lamouroux) Nam (formerly Laurencia poiteaui) on the recruitment success of Porites astreoides larvae. All species but C. poiteaui caused either recruitment inhibition or avoidance behavior in P. astreoides larvae, while L. confervoides and D. menstrualis significantly increased mortality rates of P. astreoides recruits. We also tested the effect of some of these macrophytes on larvae of the gorgonian octocoral Briareum asbestinum. Exposure to Lyngbya majuscula reduced survival and recruitment in the octocoral larvae. Our results provide evidence that algae and cyanobacteria use tactics beyond space occupation to inhibit coral recruitment. On reefs experiencing phase shifts or temporary algal blooms, the restocking of adult coral populations may be slowed due to recruitment inhibition, thereby perpetuating reduced coral cover and limiting coral community recovery. ?? Inter-Research 2006.

Coral reproduction in Western Australia

PubMed Central

Speed, Conrad W.; Babcock, Russ

2016-01-01

Larval production and recruitment underpin the maintenance of coral populations, but these early life history stages are vulnerable to extreme variation in physical conditions. Environmental managers aim to minimise human impacts during significant periods of larval production and recruitment on reefs, but doing so requires knowledge of the modes and timing of coral reproduction. Most corals are hermaphroditic or gonochoric, with a brooding or broadcast spawning mode of reproduction. Brooding corals are a significant component of some reefs and produce larvae over consecutive months. Broadcast spawning corals are more common and display considerable variation in their patterns of spawning among reefs. Highly synchronous spawning can occur on reefs around Australia, particularly on the Great Barrier Reef. On Australia’s remote north-west coast there have been fewer studies of coral reproduction. The recent industrial expansion into these regions has facilitated research, but the associated data are often contained within confidential reports. Here we combine information in this grey-literature with that available publicly to update our knowledge of coral reproduction in WA, for tens of thousands of corals and hundreds of species from over a dozen reefs spanning 20° of latitude. We identified broad patterns in coral reproduction, but more detailed insights were hindered by biased sampling; most studies focused on species of Acropora sampled over a few months at several reefs. Within the existing data, there was a latitudinal gradient in spawning activity among seasons, with mass spawning during autumn occurring on all reefs (but the temperate south-west). Participation in a smaller, multi-specific spawning during spring decreased from approximately one quarter of corals on the Kimberley Oceanic reefs to little participation at Ningaloo. Within these seasons, spawning was concentrated in March and/or April, and October and/or November, depending on the timing of the full moon. The timing of the full moon determined whether spawning was split over two months, which was common on tropical reefs. There were few data available for non-Acropora corals, which may have different patterns of reproduction. For example, the massive Porites seemed to spawn through spring to autumn on Kimberley Oceanic reefs and during summer in the Pilbara region, where other common corals (e.g. Turbinaria & Pavona) also displayed different patterns of reproduction to the Acropora. The brooding corals (Isopora & Seriatopora) on Kimberley Oceanic reefs appeared to planulate during many months, possibly with peaks from spring to autumn; a similar pattern is likely on other WA reefs. Gaps in knowledge were also due to the difficulty in identifying species and issues with methodology. We briefly discuss some of these issues and suggest an approach to quantifying variation in reproductive output throughout a year. PMID:27231651

Boat noise prevents soundscape-based habitat selection by coral planulae.

PubMed

Lecchini, David; Bertucci, Frédéric; Gache, Camille; Khalife, Adam; Besson, Marc; Roux, Natacha; Berthe, Cecile; Singh, Shubha; Parmentier, Eric; Nugues, Maggy M; Brooker, Rohan M; Dixson, Danielle L; Hédouin, Laetitia

2018-06-18

Understanding the relationship between coral reef condition and recruitment potential is vital for the development of effective management strategies that maintain coral cover and biodiversity. Coral larvae (planulae) have been shown to use certain sensory cues to orient towards settlement habitats (e.g. the odour of live crustose coralline algae - CCA). However, the influence of auditory cues on coral recruitment, and any effect of anthropogenic noise on this process, remain largely unknown. Here, we determined the effect of protected reef (MPA), exploited reef (non-MPA) soundscapes, and a source of anthropogenic noise (boat) on the habitat preference for live CCA over dead CCA in the planula of two common Indo-Pacific coral species (Pocillopora damicornis and Acropora cytherea). Soundscapes from protected reefs significantly increased the phonotaxis of planulae of both species towards live CCA, especially when compared to boat noise. Boat noise playback prevented this preferential selection of live CCA as a settlement substrate. These results suggest that sources of anthropogenic noise such as motor boat can disrupt the settlement behaviours of coral planulae. Acoustic cues should be accounted for when developing management strategies aimed at maximizing larval recruitment to coral reefs.

Centroacinar Cells Are Progenitors That Contribute to Endocrine Pancreas Regeneration

PubMed Central

Delaspre, Fabien; Beer, Rebecca L.; Rovira, Meritxell; Huang, Wei; Wang, Guangliang; Gee, Stephen; Vitery, Maria del Carmen; Wheelan, Sarah J.

2015-01-01

Diabetes is associated with a paucity of insulin-producing β-cells. With the goal of finding therapeutic routes to treat diabetes, we aim to find molecular and cellular mechanisms involved in β-cell neogenesis and regeneration. To facilitate discovery of such mechanisms, we use a vertebrate organism where pancreatic cells readily regenerate. The larval zebrafish pancreas contains Notch-responsive progenitors that during development give rise to adult ductal, endocrine, and centroacinar cells (CACs). Adult CACs are also Notch responsive and are morphologically similar to their larval predecessors. To test our hypothesis that adult CACs are also progenitors, we took two complementary approaches: 1) We established the transcriptome for adult CACs. Using gene ontology, transgenic lines, and in situ hybridization, we found that the CAC transcriptome is enriched for progenitor markers. 2) Using lineage tracing, we demonstrated that CACs do form new endocrine cells after β-cell ablation or partial pancreatectomy. We concluded that CACs and their larval predecessors are the same cell type and represent an opportune model to study both β-cell neogenesis and β-cell regeneration. Furthermore, we show that in cftr loss-of-function mutants, there is a deficiency of larval CACs, providing a possible explanation for pancreatic complications associated with cystic fibrosis. PMID:26153247

Impact of diurnal temperature fluctuations on larval settlement and growth of the reef coral Pocillopora damicornis

NASA Astrophysics Data System (ADS)

Jiang, Lei; Sun, You-Fang; Zhang, Yu-Yang; Zhou, Guo-Wei; Li, Xiu-Bao; McCook, Laurence J.; Lian, Jian-Sheng; Lei, Xin-Ming; Liu, Sheng; Cai, Lin; Qian, Pei-Yuan; Huang, Hui

2017-12-01

Diurnal fluctuations in seawater temperature are ubiquitous on tropical reef flats. However, the effects of such dynamic temperature variations on the early stages of corals are poorly understood. In this study, we investigated the responses of larvae and new recruits of Pocillopora damicornis to two constant temperature treatments (29 and 31 °C) and two diurnally fluctuating treatments (28-31 and 30-33 °C with daily means of 29 and 31 °C, respectively) simulating the 3 °C diel oscillations at 3 m depth on the Luhuitou fringing reef (Sanya, China). Results showed that the thermal stress on settlement at 31 °C was almost negated by the fluctuating treatment. Further, neither elevated temperature nor temperature fluctuations caused bleaching responses in recruits, while the maximum excitation pressure over photosystem II (PSII) was reduced under fluctuating temperatures. Although early growth and development were highly stimulated at 31 °C, oscillations of 3 °C had little effects on budding and lateral growth at either mean temperature. Nevertheless, daytime encounters with the maximum temperature of 33 °C in fluctuating 31 °C elicited a notable reduction in calcification compared to constant 31 °C. These results underscore the complexity of the effects caused by diel temperature fluctuations on early stages of corals and suggest that ecologically relevant temperature variability could buffer warming stress on larval settlement and dampen the positive effects of increased temperatures on coral growth.

Symbiodinium identity alters the temperature-dependent settlement behaviour of Acropora millepora coral larvae before the onset of symbiosis

PubMed Central

Winkler, Natalia S.; Pandolfi, John M.; Sampayo, Eugenia M.

2015-01-01

The global distribution of marine species, many of which disperse during the larval stages, is influenced by ocean temperature regimes. Here, we test how temperature and the coral symbionts (Symbiodinium) affect survival, symbiont uptake, settlement success and habitat choice of Acropora millepora larvae. Experiments were conducted at Heron Island (Australia), where larvae were exposed to 22.5, 24.5, 26.5 and 28.5°C. Within each temperature treatment, larvae were offered symbionts with distinct characteristics: (i) homologous Symbiodinium type C3, (ii) regionally homologous thermo-tolerant type D1, and (iii) heterologous thermo-tolerant type C15, as well as controls of (iv) un-filtered and (v) filtered seawater. Results show that lower instead of higher temperatures adversely affected recruitment by reducing larval survival and settlement. Low temperatures also reduced recruit habitat choice and initial symbiont densities, both of which impact on post-settlement survival. At lower temperatures, larvae increasingly settle away from preferred vertical surfaces and not on crustose coralline algae (CCA). Surprisingly, substrate preference to CCA was modified by the presence of specific symbiont genotypes that were present ex-hospite (outside the coral larvae). When different symbionts were mixed, the outcomes were non-additive, indicating that symbiont interactions modify the response. We propose that the observed influence of ex-hospite symbionts on settlement behaviour may have evolved through ecological facilitation and the study highlights the importance of biological processes during coral settlement. PMID:25589607

Crustose Coralline Algae and a Cnidarian Neuropeptide Trigger Larval Settlement in Two Coral Reef Sponges

PubMed Central

Whalan, Steve; Webster, Nicole S.; Negri, Andrew P.

2012-01-01

In sessile marine invertebrates, larval settlement is fundamental to population maintenance and persistence. Cues contributing to the settlement choices and metamorphosis of larvae have important implications for the success of individuals and populations, but cues mediating larval settlement for many marine invertebrates are largely unknown. This study assessed larval settlement in two common Great Barrier Reef sponges, Coscinoderma matthewsi and Rhopaloeides odorabile, to cues that enhance settlement and metamorphosis in various species of scleractinian coral larvae. Methanol extracts of the crustose coralline algae (CCA), Porolithon onkodes, corresponding to a range of concentrations, were used to determine the settlement responses of sponge larvae. Cnidarian neuropeptides (GLW-amide neuropeptides) were also tested as a settlement cue. Settlement in both sponge species was approximately two-fold higher in response to live chips of CCA and optimum concentrations of CCA extract compared to 0.2 µm filtered sea water controls. Metamorphosis also increased when larvae were exposed to GLW-amide neuropeptides; R. odorabile mean metamorphosis reached 42.0±5.8% compared to 16.0±2.4% in seawater controls and in C. matthewsi mean metamorphosis reached 68.3±5.4% compared to 36.7±3.3% in seawater controls. These results demonstrate the contributing role chemosensory communication plays in the ability of sponge larvae to identify suitable habitat for successful recruitment. It also raises the possibility that larvae from distinct phyla may share signal transduction pathways involved in metamorphosis. PMID:22295083

Thermal Stress Triggers Broad Pocillopora damicornis Transcriptomic Remodeling, while Vibrio coralliilyticus Infection Induces a More Targeted Immuno-Suppression Response

PubMed Central

Vidal-Dupiol, Jeremie; Dheilly, Nolwenn M.; Rondon, Rodolfo; Grunau, Christoph; Cosseau, Céline; Smith, Kristina M.; Freitag, Michael; Adjeroud, Mehdi; Mitta, Guillaume

2014-01-01

Global change and its associated temperature increase has directly or indirectly changed the distributions of hosts and pathogens, and has affected host immunity, pathogen virulence and growth rates. This has resulted in increased disease in natural plant and animal populations worldwide, including scleractinian corals. While the effects of temperature increase on immunity and pathogen virulence have been clearly identified, their interaction, synergy and relative weight during pathogenesis remain poorly documented. We investigated these phenomena in the interaction between the coral Pocillopora damicornis and the bacterium Vibrio coralliilyticus, for which the infection process is temperature-dependent. We developed an experimental model that enabled unraveling the effects of thermal stress, and virulence vs. non-virulence of the bacterium. The physiological impacts of various treatments were quantified at the transcriptome level using a combination of RNA sequencing and targeted approaches. The results showed that thermal stress triggered a general weakening of the coral, making it more prone to infection, non-virulent bacterium induced an ‘efficient’ immune response, whereas virulent bacterium caused immuno-suppression in its host. PMID:25259845

Copper and thermal perturbations on the early life processes of the hard coral Platygyra acuta

NASA Astrophysics Data System (ADS)

Kwok, C. K.; Lam, K. Y.; Leung, S. M.; Chui, A. P. Y.; Ang, P. O.

2016-09-01

Anthropogenic pollutants and climate change are major threats to coral reefs today. Yet interactions between chemical and thermal perturbations have not been fully explored in reef studies. Here, we present the single and combined effects of copper (Cu) with thermal stress on five early life-history stages/processes (fertilization, larval mortality, swimming ability, metamorphosis and growth of juvenile recruits) of the massive coral Platygyra acuta in Hong Kong. In the first four experiments, coral gametes and larvae were exposed to different Cu doses (0-200 μg L-1, apart from the fertilization assay in which 0-1000 μg L-1 was used) and temperature treatments (ambient and ambient +2 or +3 °C as a thermal stress treatment) following a factorial experimental design. Exposure time was 5 h for the fertilization assay and 48 h for the other experiments. The last experiment on growth of coral recruits was conducted over 56 d with 0-80 μg L-1 Cu used. Cu significantly reduced percent fertilization success, percentage of active swimming larvae and larval survivorship (EC50s, the half maximal effective concentrations, for percent fertilization success and percentage of active swimming larvae were 92-145 and 45-47 μg L-1 respectively. While LC50, the lethal concentration that kills 50% of the population, was 101-110 μg L-1), while growth of coral recruits was not affected at 80 μg L-1 Cu for 56 d. No settling cues were used in the settlement experiment. In their absence, percent metamorphosis increased with Cu doses, in sharp contrast to earlier findings. Settlement and metamorphosis may thus be strategies for coral larvae to escape from Cu toxicity. Thermal treatment did not significantly affect any experimental end points. This is likely because the thermal regimes used in the experiments were within the range experienced by local corals. The high variability in Cu toxicities indicates differential susceptibilities of the various life-history stages/processes of P. acuta. The level of Cu tolerance was also markedly higher than that reported in the literature for other coral species. This provides evidence to suggest possible adaptation of this species to survive in a highly polluted marine environment like that in Hong Kong.

The Use of Simulated Visible/Infrared Imager/Radiometer Suite (VIIRS) and Landsat Data Continuity Mission (LDCM) Imagery for Coral Reef Monitoring

NASA Technical Reports Server (NTRS)

Estep, L.; Spruce, J.; Blonski, S.; Moore, R.

2008-01-01

Coral reefs are some of the most biologically rich and economically important ecosystems on Earth. Coral reefs are Earth's largest biological structures and have taken thousands of years to form. Coral reefs not only provide important habitat for many marine animals and plants, but they also provide humanity with food, jobs, chemicals, protection against storms, and life-saving pharmaceuticals. Severe bleaching events have occurred that have dramatic long-term ecological impacts to corals, including loss of reef-building corals, changes in benthic habitat, and, in some cases, changes in larval fish populations (Holden and Ledrew, 1998). Some researchers suggest that 10 percent of Earth s coral reefs have already been destroyed and that another 60 percent are in danger. Scientists have proposed that as much as 95 percent of Jamaica's reefs are dying or dead. This poster reports on a Rapid Prototyping Capability (RPC) experiment done to determine whether future NASA sensors - the Visible/Infrared Imager/Radiometer Suite (VIIRS) and Landsat Data Continuity Mission (LDCM) - could generate key data products for the Integrated Coral Reef Observation Network (ICON)/Coral Reef Early Warning System (CREWS) Decision Support Tool (DST) operated by the National Oceanic and Atmospheric Administration (NOAA).

Climatic forcing and larval dispersal capabilities shape the replenishment of fishes and their habitat-forming biota on a tropical coral reef.

PubMed

Wilson, Shaun K; Depcyznski, Martial; Fisher, Rebecca; Holmes, Thomas H; Noble, Mae M; Radford, Ben T; Rule, Michael; Shedrawi, George; Tinkler, Paul; Fulton, Christopher J

2018-02-01

Fluctuations in marine populations often relate to the supply of recruits by oceanic currents. Variation in these currents is typically driven by large-scale changes in climate, in particular ENSO (El Nino Southern Oscillation). The dependence on large-scale climatic changes may, however, be modified by early life history traits of marine taxa. Based on eight years of annual surveys, along 150 km of coastline, we examined how ENSO influenced abundance of juvenile fish, coral spat, and canopy-forming macroalgae. We then investigated what traits make populations of some fish families more reliant on the ENSO relationship than others. Abundance of juvenile fish and coral recruits was generally positively correlated with the Southern Oscillation Index (SOI), higher densities recorded during La Niña years, when the ENSO-influenced Leeuwin Current is stronger and sea surface temperature higher. The relationship is typically positive and stronger among fish families with shorter pelagic larval durations and stronger swimming abilities. The relationship is also stronger at sites on the coral back reef, although the strongest of all relationships were among the lethrinids ( r  = .9), siganids ( r  = .9), and mullids ( r  = .8), which recruit to macroalgal meadows in the lagoon. ENSO effects on habitat seem to moderate SOI-juvenile abundance relationship. Macroalgal canopies are higher during La Niña years, providing more favorable habitat for juvenile fish and strengthening the SOI effect on juvenile abundance. Conversely, loss of coral following a La Niña-related heat wave may have compromised postsettlement survival of coral dependent species, weakening the influence of SOI on their abundance. This assessment of ENSO effects on tropical fish and habitat-forming biota and how it is mediated by functional ecology improves our ability to predict and manage changes in the replenishment of marine populations.

Proteomic analysis of skeletal organic matrix from the stony coral Stylophora pistillata

PubMed Central

Drake, Jeana L.; Mass, Tali; Haramaty, Liti; Zelzion, Ehud; Bhattacharya, Debashish; Falkowski, Paul G.

2013-01-01

It has long been recognized that a suite of proteins exists in coral skeletons that is critical for the oriented precipitation of calcium carbonate crystals, yet these proteins remain poorly characterized. Using liquid chromatography-tandem mass spectrometry analysis of proteins extracted from the cell-free skeleton of the hermatypic coral, Stylophora pistillata, combined with a draft genome assembly from the cnidarian host cells of the same species, we identified 36 coral skeletal organic matrix proteins. The proteome of the coral skeleton contains an assemblage of adhesion and structural proteins as well as two highly acidic proteins that may constitute a unique coral skeletal organic matrix protein subfamily. We compared the 36 skeletal organic matrix protein sequences to genome and transcriptome data from three other corals, three additional invertebrates, one vertebrate, and three single-celled organisms. This work represents a unique extensive proteomic analysis of biomineralization-related proteins in corals from which we identify a biomineralization “toolkit,” an organic scaffold upon which aragonite crystals can be deposited in specific orientations to form a phenotypically identifiable structure. PMID:23431140

Integrated mRNA and microRNA transcriptome analyses reveal regulation of thermal acclimation in Gymnocypris przewalskii: A case study in Tibetan Schizothoracine fish

PubMed Central

Tian, Fei; Zhao, Kai

2017-01-01

Environmental acclimation is important episode in wildlife occupation of the high-altitude Tibetan Plateau (TP). Transcriptome-wide studies on thermal acclimation mechanism in fish species are rarely revealed in Tibetan Plateau fish at high altitude. Thus, we used mRNA and miRNA transcriptome sequencing to investigate regulation of thermal acclimation in larval Tibetan naked carp, Gymnocypris przewalskii. We first remodeled the regulation network of mRNA and miRNA in thermal acclimation, and then identified differential expression of miRNAs and target mRNAs enriched in metabolic and digestive pathways. Interestingly, we identified two candidate genes contributed to normal skeletal development. The altered expression of these gene groups could potentially be associated with the developmental issues of deformity and induced larval death. Our results have three important implications: first, these findings provide strong evidences to support our hypothesis that G. przewalskii possess ability to build heat-tolerance against the controversial issue. Second, this study shows that transcriptional and post-transcriptional regulations are extensively involved in thermal acclimation. Third, the integrated mRNA and microRNA transcriptome analyses provide a large number of valuable genetic resources for future studies on environmental stress response in G. przewalskii and as a case study in Tibetan Schizothoracine fish. PMID:29045433

Pyrosequencing the Manduca sexta larval midgut transcriptome: messages for digestion, detoxification and defence.

PubMed

Pauchet, Y; Wilkinson, P; Vogel, H; Nelson, D R; Reynolds, S E; Heckel, D G; ffrench-Constant, R H

2010-02-01

The tobacco hornworm Manduca sexta is an important model for insect physiology but genomic and transcriptomic data are currently lacking. Following a recent pyrosequencing study generating immune related expressed sequence tags (ESTs), here we use this new technology to define the M. sexta larval midgut transcriptome. We generated over 387,000 midgut ESTs, using a combination of Sanger and 454 sequencing, and classified predicted proteins into those involved in digestion, detoxification and immunity. In many cases the depth of 454 pyrosequencing coverage allowed us to define the entire cDNA sequence of a particular gene. Many new M. sexta genes are described including up to 36 new cytochrome P450s, some of which have been implicated in the metabolism of host plant-derived nicotine. New lepidopteran gene families such as the beta-fructofuranosidases, previously thought to be restricted to Bombyx mori, are also described. An unexpectedly high number of ESTs were involved in immunity, for example 39 contigs encoding serpins, and the increasingly appreciated role of the midgut in insect immunity is discussed. Similar studies of other tissues will allow for a tissue by tissue description of the M. sexta transcriptome and will form an essential complimentary step on the road to genome sequencing and annotation.

Depth as an Organizing Force in Pocillopora damicornis: Intra-Reef Genetic Architecture

PubMed Central

Gorospe, Kelvin D.; Karl, Stephen A.

2015-01-01

Relative to terrestrial plants, and despite similarities in life history characteristics, the potential for corals to exhibit intra-reef local adaptation in the form of genetic differentiation along an environmental gradient has received little attention. The potential for natural selection to act on such small scales is likely increased by the ability of coral larval dispersal and settlement to be influenced by environmental cues. Here, we combine genetic, spatial, and environmental data for a single patch reef in Kāne‘ohe Bay, O‘ahu, Hawai‘i, USA in a landscape genetics framework to uncover environmental drivers of intra-reef genetic structuring. The genetic dataset consists of near-exhaustive sampling (n = 2352) of the coral, Pocillopora damicornis at our study site and six microsatellite genotypes. In addition, three environmental parameters – depth and two depth-independent temperature indices – were collected on a 4 m grid across 85 locations throughout the reef. We use ordinary kriging to spatially interpolate our environmental data and estimate the three environmental parameters for each colony. Partial Mantel tests indicate a significant correlation between genetic relatedness and depth while controlling for space. These results are also supported by multi-model inference. Furthermore, spatial Principle Component Analysis indicates a statistically significant genetic cline along a depth gradient. Binning the genetic dataset based on size-class revealed that the correlation between genetic relatedness and depth was significant for new recruits and increased for larger size classes, suggesting a possible role of larval habitat selection as well as selective mortality in structuring intra-reef genetic diversity. That both pre- and post-recruitment processes may be involved points to the adaptive role of larval habitat selection in increasing adult survival. The conservation importance of uncovering intra-reef patterns of genetic diversity is discussed. PMID:25806798

Connectivity, biodiversity conservation and the design of marine reserve networks for coral reefs

NASA Astrophysics Data System (ADS)

Almany, G. R.; Connolly, S. R.; Heath, D. D.; Hogan, J. D.; Jones, G. P.; McCook, L. J.; Mills, M.; Pressey, R. L.; Williamson, D. H.

2009-06-01

Networks of no-take reserves are important for protecting coral reef biodiversity from climate change and other human impacts. Ensuring that reserve populations are connected to each other and non-reserve populations by larval dispersal allows for recovery from disturbance and is a key aspect of resilience. In general, connectivity between reserves should increase as the distance between them decreases. However, enhancing connectivity may often tradeoff against a network’s ability to representatively sample the system’s natural variability. This “representation” objective is typically measured in terms of species richness or diversity of habitats, but has other important elements (e.g., minimizing the risk that multiple reserves will be impacted by catastrophic events). Such representation objectives tend to be better achieved as reserves become more widely spaced. Thus, optimizing the location, size and spacing of reserves requires both an understanding of larval dispersal and explicit consideration of how well the network represents the broader system; indeed the lack of an integrated theory for optimizing tradeoffs between connectivity and representation objectives has inhibited the incorporation of connectivity into reserve selection algorithms. This article addresses these issues by (1) updating general recommendations for the location, size and spacing of reserves based on emerging data on larval dispersal in corals and reef fishes, and on considerations for maintaining genetic diversity; (2) using a spatial analysis of the Great Barrier Reef Marine Park to examine potential tradeoffs between connectivity and representation of biodiversity and (3) describing a framework for incorporating environmental fluctuations into the conceptualization of the tradeoff between connectivity and representation, and that expresses both in a common, demographically meaningful currency, thus making optimization possible.

Thrips developmental stage-specific transcriptome response to tomato spotted wilt virus during the virus infection cycle in Frankliniella occidentalis, the primary vector.

PubMed

Schneweis, Derek J; Whitfield, Anna E; Rotenberg, Dorith

2017-01-01

Tomato spotted wilt virus (TSWV) is transmitted by Frankliniella occidentalis in a circulative-propagative manner. Little is known about thrips vector response to TSWV during the infection process from larval acquisition to adult inoculation of plants. Whole-body transcriptome response to virus infection was determined for first-instar larval, pre-pupal and adult thrips using RNA-Seq. TSWV responsive genes were identified using preliminary sequence of a draft genome of F. occidentalis as a reference and three developmental-stage transcriptomes were assembled. Processes and functions associated with host defense, insect cuticle structure and development, metabolism and transport were perturbed by TSWV infection as inferred by ontologies of responsive genes. The repertoire of genes responsive to TSWV varied between developmental stages, possibly reflecting the link between thrips development and the virus dissemination route in the vector. This study provides the foundation for exploration of tissue-specific expression in response to TSWV and functional analysis of thrips gene function. Copyright © 2016 Elsevier Inc. All rights reserved.

Protein evolution in two co-occurring types of Symbiodinium: an exploration into the genetic basis of thermal tolerance in Symbiodinium clade D

PubMed Central

2012-01-01

Background The symbiosis between reef-building corals and photosynthetic dinoflagellates (Symbiodinium) is an integral part of the coral reef ecosystem, as corals are dependent on Symbiodinium for the majority of their energy needs. However, this partnership is increasingly at risk due to changing climatic conditions. It is thought that functional diversity within Symbiodinium may allow some corals to rapidly adapt to different environments by changing the type of Symbiodinium with which they partner; however, very little is known about the molecular basis of the functional differences among symbiont groups. One group of Symbiodinium that is hypothesized to be important for the future of reefs is clade D, which, in general, seems to provide the coral holobiont (i.e., coral host and associated symbiont community) with elevated thermal tolerance. Using high-throughput sequencing data from field-collected corals we assembled, de novo, draft transcriptomes for Symbiodinium clades C and D. We then explore the functional basis of thermal tolerance in clade D by comparing rates of coding sequence evolution among the four clades of Symbiodinium most commonly found in reef-building corals (A-D). Results We are able to highlight a number of genes and functional categories as candidates for involvement in the increased thermal tolerance of clade D. These include a fatty acid desaturase, molecular chaperones and proteins involved in photosynthesis and the thylakoid membrane. We also demonstrate that clades C and D co-occur within most of the sampled colonies of Acropora hyacinthus, suggesting widespread potential for this coral species to acclimatize to changing thermal conditions via ‘shuffling’ the proportions of these two clades from within their current symbiont communities. Conclusions Transcriptome-wide analysis confirms that the four main Symbiodinium clades found within corals exhibit extensive evolutionary divergence (18.5-27.3% avg. pairwise nucleotide difference). Despite these evolutionary distinctions, many corals appear to host multiple clades simultaneously, which may allow for rapid acclimatization to changing environmental conditions. This study provides a first step toward understanding the molecular basis of functional differences between Symbiodinium clades by highlighting a number of genes with signatures consistent with positive selection along the thermally tolerant clade D lineage. PMID:23145489

Genotypic variation influences reproductive success and thermal stress tolerance in the reef building coral, Acropora palmata

NASA Astrophysics Data System (ADS)

Baums, I. B.; Devlin-Durante, M. K.; Polato, N. R.; Xu, D.; Giri, S.; Altman, N. S.; Ruiz, D.; Parkinson, J. E.; Boulay, J. N.

2013-09-01

The branching coral Acropora palmata is a foundation species of Caribbean reefs that has been decimated in recent decades by anthropogenic and natural stressors. Declines in population density and genotypic diversity likely reduce successful sexual reproduction in this self-incompatible hermaphrodite and might impede recovery. We investigated variation among genotypes in larval development under thermally stressful conditions. Six two-parent crosses and three four-parent batches were reared under three temperatures and sampled over time. Fertilization rates differed widely with two-parent crosses having lower fertilization rates (5-56 %, mean 22 % ± 22 SD) than batches (from 31 to 87 %, mean 59 % ± 28 SD). Parentage analysis of larvae in batch cultures showed differences in gamete compatibility among parents, coinciding with significant variation in both sperm morphology and egg size. While all larval batches developed more rapidly at increased water temperatures, rate of progression through developmental stages varied among batches, as did swimming speed. Together, these results indicate that loss of genotypic diversity exacerbates already severe limitations in sexual reproductive success of A. palmata. Nevertheless, surviving parental genotypes produce larvae that do vary in their phenotypic response to thermal stress, with implications for adaptation, larval dispersal and population connectivity in the face of warming sea surface temperatures.

Larval export from marine reserves and the recruitment benefit for fish and fisheries.

PubMed

Harrison, Hugo B; Williamson, David H; Evans, Richard D; Almany, Glenn R; Thorrold, Simon R; Russ, Garry R; Feldheim, Kevin A; van Herwerden, Lynne; Planes, Serge; Srinivasan, Maya; Berumen, Michael L; Jones, Geoffrey P

2012-06-05

Marine reserves, areas closed to all forms of fishing, continue to be advocated and implemented to supplement fisheries and conserve populations. However, although the reproductive potential of important fishery species can dramatically increase inside reserves, the extent to which larval offspring are exported and the relative contribution of reserves to recruitment in fished and protected populations are unknown. Using genetic parentage analyses, we resolve patterns of larval dispersal for two species of exploited coral reef fish within a network of marine reserves on the Great Barrier Reef. In a 1,000 km(2) study area, populations resident in three reserves exported 83% (coral trout, Plectropomus maculatus) and 55% (stripey snapper, Lutjanus carponotatus) of assigned offspring to fished reefs, with the remainder having recruited to natal reserves or other reserves in the region. We estimate that reserves, which account for just 28% of the local reef area, produced approximately half of all juvenile recruitment to both reserve and fished reefs within 30 km. Our results provide compelling evidence that adequately protected reserve networks can make a significant contribution to the replenishment of populations on both reserve and fished reefs at a scale that benefits local stakeholders. Copyright © 2012 Elsevier Ltd. All rights reserved.

A key phase in the recruitment dynamics of coral reef fishes: post-settlement transition

USGS Publications Warehouse

Kaufman, L.; Ebersole, J.L.; Beets, Jim; McIvor, Carole

1992-01-01

Recent studies of recruitment dynamics in demersal fishes have placed major emphasis on presettlement mortality, and little on events bridging late larval and early juvenile periods. Observations on 68 taxa of Caribbean coral reef fishes before and during settlement revealed the existence of a distinct post-settlement life phase called the transition juvenile, associated with the act of recruitment. Transition juveniles were found as solitary individuals, in conspecific groups, or in heterospecific groups. The groups were either uniform or heterogenous in appearance. The complexity of the transition phase and its apparently widespread occurrence in coral reef fishes suggests that important aspects of population structure may be determined between settlement and first appearance as a full-fledged juvenile.

Fine-scale analysis of genetic structure in the brooding coral Seriatopora hystrix from the Red Sea

NASA Astrophysics Data System (ADS)

Maier, E.; Tollrian, R.; Nürnberger, B.

2009-09-01

The dispersal of gametes and larvae plays a key role in the population dynamics of sessile marine invertebrates. Species with internal fertilisation are often associated with very localised larval dispersal, which may cause small-scale patterns of neutral genetic variation. This study on the brooding coral Seriatopora hystrix from the Red Sea focused on the smallest possible scale: Two S. hystrix stands (~100 colonies each) near Dahab were completely sampled, mapped and analysed at five microsatellite markers. The sexual mode of reproduction, the likely occurrence of selfing and the level of immigration were in agreement with previous studies on this species. Contrary to previous findings, both stands were in Hardy-Weinberg proportions. Also, no evidence for spatially restricted larval dispersal within the sampled areas was found. Differences between this and previous studies on S. hystrix could reflect variation in life history or varying environmental conditions, which opens intriguing questions for future research.

Comparative genomics explains the evolutionary success of reef-forming corals.

PubMed

Bhattacharya, Debashish; Agrawal, Shobhit; Aranda, Manuel; Baumgarten, Sebastian; Belcaid, Mahdi; Drake, Jeana L; Erwin, Douglas; Foret, Sylvian; Gates, Ruth D; Gruber, David F; Kamel, Bishoy; Lesser, Michael P; Levy, Oren; Liew, Yi Jin; MacManes, Matthew; Mass, Tali; Medina, Monica; Mehr, Shaadi; Meyer, Eli; Price, Dana C; Putnam, Hollie M; Qiu, Huan; Shinzato, Chuya; Shoguchi, Eiichi; Stokes, Alexander J; Tambutté, Sylvie; Tchernov, Dan; Voolstra, Christian R; Wagner, Nicole; Walker, Charles W; Weber, Andreas Pm; Weis, Virginia; Zelzion, Ehud; Zoccola, Didier; Falkowski, Paul G

2016-05-24

Transcriptome and genome data from twenty stony coral species and a selection of reference bilaterians were studied to elucidate coral evolutionary history. We identified genes that encode the proteins responsible for the precipitation and aggregation of the aragonite skeleton on which the organisms live, and revealed a network of environmental sensors that coordinate responses of the host animals to temperature, light, and pH. Furthermore, we describe a variety of stress-related pathways, including apoptotic pathways that allow the host animals to detoxify reactive oxygen and nitrogen species that are generated by their intracellular photosynthetic symbionts, and determine the fate of corals under environmental stress. Some of these genes arose through horizontal gene transfer and comprise at least 0.2% of the animal gene inventory. Our analysis elucidates the evolutionary strategies that have allowed symbiotic corals to adapt and thrive for hundreds of millions of years.

Transcriptome, expression, and activity analyses reveal a vital heat shock protein 70 in the stress response of stony coral Pocillopora damicornis.

PubMed

Zhang, Yidan; Zhou, Zhi; Wang, Lingui; Huang, Bo

2018-02-12

Coral bleaching occurs worldwide with increasing frequencies and intensities, which is caused by the stress response of stony coral to environmental change, especially increased sea surface temperature. In the present study, transcriptome, expression, and activity analyses were employed to illustrate the underlying molecular mechanisms of heat shock protein 70 (HSP70) in the stress response of coral to environmental changes. The domain analyses of assembled transcripts revealed 30 HSP70 gene contigs in stony coral Pocillopora damicornis. One crucial HSP70 (PdHSP70) was observed, whose expressions were induced by both elevated temperature and ammonium after expression difference analysis. The complete complementary DNA (cDNA) sequence of PdHSP70 was identified, which encoded a polypeptide of 650 amino acids with a molecular weight of 71.93 kDa. The deduced amino acid sequence of PdHSP70 contained a HSP70 domain (from Pro8 to Gly616), and it shared the highest similarity (95%) with HSP70 from Stylophora pistillata. The expression level of PdHSP70 gene increased significantly at 12 h, and returned to the initial level at 24 h after the stress of high temperature (32 °C). The cDNA fragment encoding the mature peptide of PdHSP70 was recombined and expressed in the prokaryotic expression system. The ATPase activity of recombinant PdHSP70 protein was determined, and it did not change significantly in a wide range of temperature from 25 to 40 °C. These results collectively suggested that PdHSP70 was a vital heat shock protein 70 in the stony coral P. damicornis, whose mRNA expression could be induced by diverse environmental stress and whose activity could remain stable under heat stress. PdHSP70 might be involved in the regulation of the bleaching owing to heat stress in the stony coral P. damicornis.

De Novo Assembly and Characterization of Four Anthozoan (Phylum Cnidaria) Transcriptomes.

PubMed

Kitchen, Sheila A; Crowder, Camerron M; Poole, Angela Z; Weis, Virginia M; Meyer, Eli

2015-09-17

Many nonmodel species exemplify important biological questions but lack the sequence resources required to study the genes and genomic regions underlying traits of interest. Reef-building corals are famously sensitive to rising seawater temperatures, motivating ongoing research into their stress responses and long-term prospects in a changing climate. A comprehensive understanding of these processes will require extending beyond the sequenced coral genome (Acropora digitifera) to encompass diverse coral species and related anthozoans. Toward that end, we have assembled and annotated reference transcriptomes to develop catalogs of gene sequences for three scleractinian corals (Fungia scutaria, Montastraea cavernosa, Seriatopora hystrix) and a temperate anemone (Anthopleura elegantissima). High-throughput sequencing of cDNA libraries produced ~20-30 million reads per sample, and de novo assembly of these reads produced ~75,000-110,000 transcripts from each sample with size distributions (mean ~1.4 kb, N50 ~2 kb), comparable to the distribution of gene models from the coral genome (mean ~1.7 kb, N50 ~2.2 kb). Each assembly includes matches for more than half the gene models from A. digitifera (54-67%) and many reasonably complete transcripts (~5300-6700) spanning nearly the entire gene (ortholog hit ratios ≥0.75). The catalogs of gene sequences developed in this study made it possible to identify hundreds to thousands of orthologs across diverse scleractinian species and related taxa. We used these sequences for phylogenetic inference, recovering known relationships and demonstrating superior performance over phylogenetic trees constructed using single mitochondrial loci. The resources developed in this study provide gene sequences and genetic markers for several anthozoan species. To enhance the utility of these resources for the research community, we developed searchable databases enabling researchers to rapidly recover sequences for genes of interest. Our analysis of de novo assembly quality highlights metrics that we expect will be useful for evaluating the relative quality of other de novo transcriptome assemblies. The identification of orthologous sequences and phylogenetic reconstruction demonstrates the feasibility of these methods for clarifying the substantial uncertainties in the existing scleractinian phylogeny. Copyright © 2015 Kitchen et al.

Transcriptome dynamics over a lunar month in a broadcast spawning acroporid coral.

PubMed

Oldach, Matthew J; Workentine, Matthew; Matz, Mikhail V; Fan, Tung-Yung; Vize, Peter D

2017-05-01

On one night per year, at a specific point in the lunar cycle, one of the most extraordinary reproductive events on the planet unfolds as hundreds of millions of broadcast spawning corals release their trillions of gametes into the waters of the tropical seas. Each species spawns on a specific night within the lunar cycle, typically from full moon to third quarter moon, and in a specific time window after sunset. This accuracy is essential to achieve efficient fertilization in the vastness of the oceans. In this report, we use transcriptome sequencing at noon and midnight across an entire lunar cycle to explore how acroporid corals interpret lunar signals. The data were interrogated by both time-of-day-dependent and time-of-day-independent methods to identify different types of lunar cycles. Time-of-day methods found that genes associated with biological clocks and circadian processes change their diurnal cycles over the course of a synodic lunar cycle. Some genes have large differences between day and night at some lunar phases, but little or no diurnal differences at other phases. Many clock genes display an oscillation pattern indicative of phase shifts linked to the lunar cycle. Time-independent methods found that signal transduction, protein secretion and modification, cell cycle and ion transport change over the lunar timescale and peak at various phases of the moon. Together these data provide unique insights into how the moon impinges on coral transcription cycles and how lunar light may regulate circalunar timing systems and coral biology. © 2017 John Wiley & Sons Ltd.

Settling into an increasingly hostile world: the rapidly closing "recruitment window" for corals.

PubMed

Arnold, Suzanne N; Steneck, Robert S

2011-01-01

Free space is necessary for larval recruitment in all marine benthic communities. Settling corals, with limited energy to invest in competitive interactions, are particularly vulnerable during settlement into well-developed coral reef communities. This situation may be exacerbated for corals settling into coral-depauperate reefs where succession in nursery microhabitats moves rapidly toward heterotrophic organisms inhospitable to settling corals. To study effects of benthic organisms (at millimeter to centimeter scales) on newly settled corals and their survivorship we deployed terra-cotta coral settlement plates at 10 m depth on the Mesoamerican Barrier Reef in Belize and monitored them for 38 mo. During the second and third years, annual recruitment rates declined by over 50% from the previous year. Invertebrate crusts (primarily sponges) were absent at the start of the experiment but increased in abundance annually from 39, 60, to 73% of the plate undersides by year three. Subsequently, substrates hospitable to coral recruitment, including crustose coralline algae, biofilmed terra-cotta and polychaete tubes, declined. With succession, substrates upon which spat settled shifted toward organisms inimical to survivorship. Over 50% of spat mortality was due to overgrowth by sponges alone. This result suggests that when a disturbance creates primary substrate a "recruitment window" for settling corals exists from approximately 9 to 14 mo following the disturbance. During the window, early-succession, facilitating species are most abundant. The window closes as organisms hostile to coral settlement and survivorship overgrow nursery microhabitats.

The transcriptomic and evolutionary signature of social interactions regulating honey bee caste development.

PubMed

Vojvodic, Svjetlana; Johnson, Brian R; Harpur, Brock A; Kent, Clement F; Zayed, Amro; Anderson, Kirk E; Linksvayer, Timothy A

2015-11-01

The caste fate of developing female honey bee larvae is strictly socially regulated by adult nurse workers. As a result of this social regulation, nurse-expressed genes as well as larval-expressed genes may affect caste expression and evolution. We used a novel transcriptomic approach to identify genes with putative direct and indirect effects on honey bee caste development, and we subsequently studied the relative rates of molecular evolution at these caste-associated genes. We experimentally induced the production of new queens by removing the current colony queen, and we used RNA sequencing to study the gene expression profiles of both developing larvae and their caregiving nurses before and after queen removal. By comparing the gene expression profiles of queen-destined versus worker-destined larvae as well as nurses observed feeding these two types of larvae, we identified larval and nurse genes associated with caste development. Of 950 differentially expressed genes associated with caste, 82% were expressed in larvae with putative direct effects on larval caste, and 18% were expressed in nurses with putative indirect effects on caste. Estimated selection coefficients suggest that both nurse and larval genes putatively associated with caste are rapidly evolving, especially those genes associated with worker development. Altogether, our results suggest that indirect effect genes play important roles in both the expression and evolution of socially influenced traits such as caste.

Encounter with mesoscale eddies enhances survival to settlement in larval coral reef fishes

PubMed Central

Shulzitski, Kathryn; Sponaugle, Su; Hauff, Martha; Walter, Kristen D.; Cowen, Robert K.

2016-01-01

Oceanographic features, such as eddies and fronts, enhance and concentrate productivity, generating high-quality patches that dispersive marine larvae may encounter in the plankton. Although broad-scale movement of larvae associated with these features can be captured in biophysical models, direct evidence of processes influencing survival within them, and subsequent effects on population replenishment, are unknown. We sequentially sampled cohorts of coral reef fishes in the plankton and nearshore juvenile habitats in the Straits of Florida and used otolith microstructure analysis to compare growth and size-at-age of larvae collected inside and outside of mesoscale eddies to those that survived to settlement. Larval habitat altered patterns of growth and selective mortality: Thalassoma bifasciatum and Cryptotomus roseus that encountered eddies in the plankton grew faster than larvae outside of eddies and likely experienced higher survival to settlement. During warm periods, T. bifasciatum residing outside of eddies in the oligotrophic Florida Current experienced high mortality and only the slowest growers survived early larval life. Such slow growth is advantageous in nutrient poor habitats when warm temperatures increase metabolic demands but is insufficient for survival beyond the larval stage because only fast-growing larvae successfully settled to reefs. Because larvae arriving to the Straits of Florida from distant sources must spend long periods of time outside of eddies, our results indicate that they have a survival disadvantage. High productivity features such as eddies not only enhance the survival of pelagic larvae, but also potentially increase the contribution of locally spawned larvae to reef populations. PMID:27274058

Larval Behaviours and Their Contribution to the Distribution of the Intertidal Coral Reef Sponge Carteriospongia foliascens

PubMed Central

Abdul Wahab, Muhammad Azmi; de Nys, Rocky; Webster, Nicole; Whalan, Steve

2014-01-01

Sponges (Phylum Porifera) are an evolutionary and ecologically significant group; however information on processes influencing sponge population distributions is surprisingly limited. Carteriospongia foliascens is a common Indo-Pacific sponge, which has been reported from the intertidal to the mesophotic. Interestingly, the distribution of C. foliascens at inshore reefs of the Great Barrier Reef is restricted to the intertidal with no individuals evident in adjacent subtidal habitats. The abundance of C. foliascens and substrate availability was first quantified to investigate the influence of substrate limitation on adult distribution. Pre-settlement processes of larval spawning, swimming speeds, phototaxis, vertical migration, and settlement to intertidal and subtidal substrate cues were also quantified. Notably, suitable settlement substrate (coral rubble) was not limiting in subtidal habitats. C. foliascens released up to 765 brooded larvae sponge−1 day−1 during the day, with larvae (80%±5.77) being negatively phototactic and migrating to the bottom within 40 minutes from release. Subsequently, larvae (up to 58.67%±2.91) migrated to the surface after the loss of the daylight cue (nightfall), and after 34 h post-release >98.67% (±0.67) of larvae had adopted a benthic habit regardless of light conditions. Intertidal and subtidal biofilms initiated similar settlement responses, inducing faster (as early 6 h post-release) and more successful metamorphosis (>60%) than unconditioned surfaces. C. foliascens has a high larval supply and larval behaviours that support recruitment to the subtidal. The absence of C. foliascens in subtidal habitats at inshore reefs is therefore proposed to be a potential consequence of post-settlement mortalities. PMID:24853091

Early-phase dynamics in coral recovery following cyclone disturbance on the inshore Great Barrier Reef, Australia

NASA Astrophysics Data System (ADS)

Sato, Yui; Bell, Sara C.; Nichols, Cassandra; Fry, Kent; Menéndez, Patricia; Bourne, David G.

2018-06-01

Coral recovery (the restoration of abundance and composition of coral communities) after disturbance is a key process that determines the resilience of reef ecosystems. To understand the mechanisms underlying the recovery process of coral communities, colony abundance and size distribution were followed on reefs around Pelorus Island, located in the inshore central region of the Great Barrier Reef, following a severe tropical cyclone in 2011 that caused dramatic loss of coral communities. Permanent quadrats (600 m2) were monitored biannually between 2012 and 2016, and individual coral colonies were counted, sized and categorized into morphological types. The abundance of coral recruits and coral cover were also examined using permanent quadrats and random line intercept transects, respectively. The number of colonies in the smallest size class (4-10 cm) increased substantially during the study period, driving the recovery of coral populations. The total number of coral colonies 5 yr post-cyclone reached between 73 and 122% of pre-cyclone levels though coral cover remained between 16 and 31% of pre-cyclone levels, due to the dominance of small coral colonies in the recovering communities. Temporal transitions of coral demography (i.e., colony-size distributions) illustrated that the number of recently established coral populations overtook communities of surviving colonies. Coral recruits (< 4 cm in size) also showed increasing patterns in abundance over the study period, underscoring the importance of larval supply in coral recovery. A shift in morphological composition of coral communities was also observed, with the relative abundance of encrusting corals reduced post-cyclone in contrast to their dominance prior to the disturbance. This study identifies the fine-scale processes involved in the initial recovery of coral reefs, providing insights into the dynamics of coral demography that are essential for determining coral reef resilience following major disturbance.

RNA-seq of Rice Yellow Stem Borer Scirpophaga incertulas Reveals Molecular Insights During Four Larval Developmental Stages

PubMed Central

Renuka, Pichili; Madhav, Maganti S.; Padmakumari, Ayyagari Phani; Barbadikar, Kalyani M.; Mangrauthia, Satendra K.; Vijaya Sudhakara Rao, Kola; Marla, Soma S.; Ravindra Babu, Vemuri

2017-01-01

The yellow stem borer (YSB), Scirpophaga incertulas, is a prominent pest in rice cultivation causing serious yield losses. The larval stage is an important stage in YSB, responsible for maximum infestation. However, limited knowledge exists on the biology and mechanisms underlying the growth and differentiation of YSB. To understand and identify the genes involved in YSB development and infestation, so as to design pest control strategies, we performed de novo transcriptome analysis at the first, third, fifth, and seventh larval developmental stages employing Illumina Hi-seq. High-quality reads (HQR) of ∼229 Mb were assembled into 24,775 transcripts with an average size of 1485 bp. Genes associated with various metabolic processes, i.e., detoxification mechanism [CYP450, GSTs, and carboxylesterases (CarEs)], RNA interference (RNAi) machinery (Dcr-1, Dcr-2, Ago-1, Ago-2, Sid-1, Sid-2, Sid-3, and Sid-1-related gene), chemoreception (CSPs, GRs, OBPs, and ORs), and regulators [transcription factors (TFs) and hormones] were differentially regulated during the developmental stages. Identification of stage-specific transcripts made it possible to determine the essential processes of larval development. Comparative transcriptome analysis revealed that YSB has not evolved much with respect to the detoxification mechanism, but showed the presence of distinct RNAi machinery. The presence of strong specific visual recognition coupled with chemosensory mechanisms supports the monophagous nature of YSB. Designed expressed sequenced tags-simple-sequence repeats (EST-SSRs) will facilitate accurate estimation of the genetic diversity of YSB. This is the first report on characterization of the YSB transcriptome and the identification of genes involved in key processes, which will help researchers and industry to devise novel pest control strategies. This study also opens up a new avenue to develop next-generation resistant rice using RNAi or genome editing approaches. PMID:28717048

The Good, The Bad, and The Distant: Soundscape Cues for Larval Fish.

PubMed

Piercy, Julius J B; Smith, David J; Codling, Edward A; Hill, Adam J; Simpson, Stephen D

2016-01-01

Coral reef noise is an important navigation cue for settling reef fish larvae and can thus potentially affect reef population dynamics. Recent evidence has shown that fish are able to discriminate between the soundscapes of different types of habitat (e.g., mangrove and reef). In this study, we investigated whether discernible acoustic differences were present between sites within the same coral reef system. Differences in sound intensity and transient content were found between sites, but site-dependent temporal variation was also present. We discuss the implications of these findings for settling fish larvae.

Evidence of host-associated divergence from coral-eating snails (genus Coralliophila) in the Coral Triangle

NASA Astrophysics Data System (ADS)

Simmonds, Sara E.; Chou, Vincent; Cheng, Samantha H.; Rachmawati, Rita; Calumpong, Hilconida P.; Ngurah Mahardika, G.; Barber, Paul H.

2018-06-01

We studied how host-associations and geography shape the genetic structure of sister species of marine snails Coralliophila radula (A. Adams, 1853) and C. violacea (Kiener, 1836). These obligate ectoparasites prey upon corals and are sympatric throughout much of their ranges in coral reefs of the tropical and subtropical Indo-Pacific. We tested for population genetic structure of snails in relation to geography and their host corals using mtDNA (COI) sequences in minimum spanning trees and AMOVAs. We also examined the evolutionary relationships of their Porites host coral species using maximum likelihood trees of RAD-seq (restriction site-associated DNA sequencing) loci mapped to a reference transcriptome. A maximum likelihood tree of host corals revealed three distinct clades. Coralliophila radula showed a pronounced genetic break across the Sunda Shelf ( Φ CT = 0.735) but exhibited no genetic structure with respect to host. C. violacea exhibited significant geographic structure ( Φ CT = 0.427), with divergence among Hawaiian populations, the Coral Triangle and the Indian Ocean. Notably, C. violacea showed evidence of ecological divergence; two lineages were associated with different groups of host coral species, one widespread found at all sites, and the other restricted to the Coral Triangle. Sympatric populations of C. violacea found on different suites of coral species were highly divergent ( Φ CT = 0.561, d = 5.13%), suggesting that symbiotic relationships may contribute to lineage diversification in the Coral Triangle.

Coral reef recovery in Florida and the Persian Gulf

USGS Publications Warehouse

Shinn, Eugene A.

1976-01-01

Long-term observations and study of coral reef destruction by hurricanes in the Florida Keys show, surprisingly, that although corals are devastated on a grand scale during storms, recovery is rapid. Recovery occurs because of the widespread scattering of live fragments, many of which become growth sites of new colonies. Reef recovery from death by chilling in the Persian Gulf was well under way when last observed, but it is not yet known if the recovery rate was as rapid as recovery from the storm destruction in Florida. Recovery from death by chilling requires settlement of transported coral larvae and a substrate suitable for larval attachment. Such resettlement is subject to the effects of currents, predators, pollution, and competition for substrate. A growth rate of 10 cm per year combined with geometrical progression of branch formation accounts for rapid recovery. Although calculated coral proliferation seems unusually high, it has been confirmed by serial underwater photographs spanning ten years. More precise measurements of growth and branching are needed, along with growth data for other common reef-building corals. Such data would be useful for predicting standing crop of a restocked or transplanted reef.

Biotic Control of Skeletal Growth by Scleractinian Corals in Aragonite–Calcite Seas

PubMed Central

Higuchi, Tomihiko; Fujimura, Hiroyuki; Yuyama, Ikuko; Harii, Saki; Agostini, Sylvain; Oomori, Tamotsu

2014-01-01

Modern scleractinian coral skeletons are commonly composed of aragonite, the orthorhombic form of CaCO3. Under certain conditions, modern corals produce calcite as a secondary precipitate to fill pore space. However, coral construction of primary skeletons from calcite has yet to be demonstrated. We report a calcitic primary skeleton produced by the modern scleractinian coral Acropora tenuis. When uncalcified juveniles were incubated from the larval stage in seawater with low mMg/Ca levels, the juveniles constructed calcitic crystals in parts of the primary skeleton such as the septa; the deposits were observable under Raman microscopy. Using scanning electron microscopy, we observed different crystal morphologies of aragonite and calcite in a single juvenile skeleton. Quantitative analysis using X-ray diffraction showed that the majority of the skeleton was composed of aragonite even though we had exposed the juveniles to manipulated seawater before their initial crystal nucleation and growth processes. Our results indicate that the modern scleractinian coral Acropora mainly produces aragonite skeletons in both aragonite and calcite seas, but also has the ability to use calcite for part of its skeletal growth when incubated in calcite seas. PMID:24609012

Doors are closing on early development in corals facing climate change

NASA Astrophysics Data System (ADS)

Keshavmurthy, Shashank; Fontana, Silvia; Mezaki, Takuma; González, Laura Del Caño; Chen, Chaolun Allen

2014-07-01

Marine invertebrates are particularly vulnerable to climatic anomalies in early life history stages because of the time spent in the water column. Studies have focused on the effect of seawater temperature on fertilization, development, and larval stages in corals; however, none of them show comparative results along an environmental gradient. In this study, we show that temperatures in the range of 15-33°C have strong effects on fertilization rates and embryonic stages of two coral species, Acropora muricata in the subtropical environment and Acropora hyacinthus in subtropical and temperate environments. Deformations after the first cleavage stages were observed at low (15°C) and high (33°C) temperatures. Development was delayed by 6-7 h in the slightly non-optimal temperature of 20°C. We found significant differences in fertilization rates and responses of embryos from different latitudes, with temperate corals being more sensitive to extremely hot temperatures and vice versa. We hypothesize that the coral development is restricted to a narrow temperature range and deviation outside this window could inhibit a species' continuance and ecological success. Thus, it would have significant negative effects on adult populations and communities, playing a role in future of coral reef survival.

Keeping It Local: Dispersal Limitations of Coral Larvae to the High Latitude Coral Reefs of the Houtman Abrolhos Islands.

PubMed

Markey, Kathryn L; Abdo, Dave A; Evans, Scott N; Bosserelle, Cyprien

2016-01-01

In 2011 the first recorded bleaching event for the high latitude Houtman Abrolhos Islands (HAI) coral communities was documented. This bleaching event highlighted the question of whether a supply of 'heat tolerant' coral recruits from the tropical north would be sufficient to provide a level of resistance for these reefs to future warming events. Using Lagrangian modelling we showed that due to its regional isolation, large-scale larval input from potential tropical northern source populations to the HAI is unlikely, despite the southward flowing Leeuwin current. Successful recruitment to artificial substrates was recorded following the bleaching event. However, this was negligible (0.4 ± 0.1 recruits per tile) compared to 2013 post impact recruitment (128.8 ± 15.8 recruits per tile). Our data therefore provides preliminary evidence suggesting that the connectivity of the HAI with coral communities in the north is limited, and population maintenance and recovery is likely driven primarily by self-recruitment. Given the low thermal tolerance of the HAI coral communities, the dominance of Acropora, and the apparent reliance on self-recruitment, an increased frequency of thermally anomalous conditions at the HAI (such as experienced in 2011) has the potential to reduce the long-term stability of the HAI coral populations and species that depend upon them.

Transcriptome Analysis of the Emerald Ash Borer (EAB), Agrilus planipennis: De Novo Assembly, Functional Annotation and Comparative Analysis.

PubMed

Duan, Jun; Ladd, Tim; Doucet, Daniel; Cusson, Michel; vanFrankenhuyzen, Kees; Mittapalli, Omprakash; Krell, Peter J; Quan, Guoxing

2015-01-01

The Emerald ash borer (EAB), Agrilus planipennis, is an invasive phloem-feeding insect pest of ash trees. Since its initial discovery near the Detroit, US- Windsor, Canada area in 2002, the spread of EAB has had strong negative economic, social and environmental impacts in both countries. Several transcriptomes from specific tissues including midgut, fat body and antenna have recently been generated. However, the relatively low sequence depth, gene coverage and completeness limited the usefulness of these EAB databases. High-throughput deep RNA-Sequencing (RNA-Seq) was used to obtain 473.9 million pairs of 100 bp length paired-end reads from various life stages and tissues. These reads were assembled into 88,907 contigs using the Trinity strategy and integrated into 38,160 unigenes after redundant sequences were removed. We annotated 11,229 unigenes by searching against the public nr, Swiss-Prot and COG. The EAB transcriptome assembly was compared with 13 other sequenced insect species, resulting in the prediction of 536 unigenes that are Coleoptera-specific. Differential gene expression revealed that 290 unigenes are expressed during larval molting and 3,911 unigenes during metamorphosis from larvae to pupae, respectively (FDR< 0.01 and log2 FC>2). In addition, 1,167 differentially expressed unigenes were identified from larval and adult midguts, 435 unigenes were up-regulated in larval midgut and 732 unigenes were up-regulated in adult midgut. Most of the genes involved in RNA interference (RNAi) pathways were identified, which implies the existence of a system RNAi in EAB. This study provides one of the most fundamental and comprehensive transcriptome resources available for EAB to date. Identification of the tissue- stage- or species- specific unigenes will benefit the further study of gene functions during growth and metamorphosis processes in EAB and other pest insects.

Transcriptome Analysis of the Emerald Ash Borer (EAB), Agrilus planipennis: De Novo Assembly, Functional Annotation and Comparative Analysis

PubMed Central

Duan, Jun; Ladd, Tim; Doucet, Daniel; Cusson, Michel; vanFrankenhuyzen, Kees; Mittapalli, Omprakash; Krell, Peter J.; Quan, Guoxing

2015-01-01

Background The Emerald ash borer (EAB), Agrilus planipennis, is an invasive phloem-feeding insect pest of ash trees. Since its initial discovery near the Detroit, US- Windsor, Canada area in 2002, the spread of EAB has had strong negative economic, social and environmental impacts in both countries. Several transcriptomes from specific tissues including midgut, fat body and antenna have recently been generated. However, the relatively low sequence depth, gene coverage and completeness limited the usefulness of these EAB databases. Methodology and Principal Findings High-throughput deep RNA-Sequencing (RNA-Seq) was used to obtain 473.9 million pairs of 100 bp length paired-end reads from various life stages and tissues. These reads were assembled into 88,907 contigs using the Trinity strategy and integrated into 38,160 unigenes after redundant sequences were removed. We annotated 11,229 unigenes by searching against the public nr, Swiss-Prot and COG. The EAB transcriptome assembly was compared with 13 other sequenced insect species, resulting in the prediction of 536 unigenes that are Coleoptera-specific. Differential gene expression revealed that 290 unigenes are expressed during larval molting and 3,911 unigenes during metamorphosis from larvae to pupae, respectively (FDR< 0.01 and log2 FC>2). In addition, 1,167 differentially expressed unigenes were identified from larval and adult midguts, 435 unigenes were up-regulated in larval midgut and 732 unigenes were up-regulated in adult midgut. Most of the genes involved in RNA interference (RNAi) pathways were identified, which implies the existence of a system RNAi in EAB. Conclusions and Significance This study provides one of the most fundamental and comprehensive transcriptome resources available for EAB to date. Identification of the tissue- stage- or species- specific unigenes will benefit the further study of gene functions during growth and metamorphosis processes in EAB and other pest insects. PMID:26244979

A cross-ocean comparison of responses to settlement cues in reef-building corals

PubMed Central

Meyer, Eli; Guermond, Sarah M.; Matz, Mikhail V.

2014-01-01

Caribbean coral reefs have deteriorated substantially over the past 30 years, which is broadly attributable to the effects of global climate change. In the same time, Indo-Pacific reefs maintain higher coral cover and typically recover rapidly after disturbances. This difference in reef resilience is largely due to much higher coral recruitment rates in the Pacific. We hypothesized that the lack of Caribbean recruitment might be explained by diminishing quality of settlement cues and/or impaired sensitivity of Caribbean coral larvae to those cues, relative to the Pacific. To evaluate this hypothesis, we assembled a collection of bulk samples of reef encrusting communities, mostly consisting of crustose coralline algae (CCA), from various reefs around the world and tested them as settlement cues for several coral species originating from different ocean provinces. Cue samples were meta-barcoded to evaluate their taxonomic diversity. We observed no systematic differences either in cue potency or in strength of larval responses depending on the ocean province, and no preference of coral larvae towards cues from the same ocean. Instead, we detected significant differences in cue preferences among coral species, even for corals originating from the same reef. We conclude that the region-wide disruption of the settlement process is unlikely to be the major cause of Caribbean reef loss. However, due to their high sensitivity to the effects of climate change, shifts in the composition of CCA-associated communities, combined with pronounced differences in cue preferences among coral species, could substantially influence future coral community structure. PMID:24765568

Population collapse dynamics in Acropora downingi, an Arabian/Persian Gulf ecosystem-engineering coral, linked to rising temperature.

PubMed

Riegl, Bernhard; Johnston, Matthew; Purkis, Sam; Howells, Emily; Burt, John; Steiner, Sascha C C; Sheppard, Charles R C; Bauman, Andrew

2018-03-05

As in the tropical Atlantic, Acropora populations in the southern Persian/Arabian Gulf plummeted within two decades after having been ecosystem engineers on most wave-exposed reefs since the Pleistocene. Since 1996/1998 live coral cover in the Gulf declined by over 90% in many areas, primarily due to bleaching and diseases caused by rising temperatures. In the formerly dominant table-coral species A. downingi, population dynamics corresponding to disturbance regimes was quantified in three transition matrices (lower disturbance pre-1996; moderate disturbance from 1998 to 2010 and 2013 to 2017, disturbed in 1996/1998, 2010/11/12, 2017). Increased disturbance frequency and severity caused progressive reduction in coral size, cover, and population fecundity. Small size-classes were bolstered more by partial colony mortality than sexual recruitment. Some large corals had a size refuge and resisted die-back but were also lost with increasing disturbance. Matrix and biophysical larval flow models suggested one metapopulation. Southern, Arabian, populations could be connected to northern, Iranian, populations but this connectivity was lost under assumptions of pelagic larval duration at rising temperatures shortened to a third. Then, the metapopulation disintegrated into isolated populations. Connectivity required to avoid extinctions increased exponentially with disturbance frequency and correlation of disturbances across the metapopulation. Populations became unsustainable at eight disturbances in 15 years, when even highest theoretical recruitment no longer compensated mortality. This lethal disturbance frequency was 3-fold that of the moderately disturbed monitoring period and 4-fold of the preceding low-disturbance period-suggesting ongoing shortening of the disturbance-free period. Observed population collapse and environmental changes in the Gulf suggest that A. downingi is heading toward at least functional extinction mainly due to increasingly frequent temperature-induced mortality events, clearly linked to climate change. © 2018 John Wiley & Sons Ltd.

Effects of drill cuttings on larvae of the cold-water coral Lophelia pertusa

NASA Astrophysics Data System (ADS)

Järnegren, Johanna; Brooke, Sandra; Jensen, Henrik

2017-03-01

Fossil fuel consumption is predicted to dominate energy needs until at least 2040. To make up for reduced production from maturing fields, oil and gas exploration activities on the Norwegian continental shelf have greatly increased over the past several years. Strict emission controls have resulted in a substantial reduction in the release of hazardous chemicals. However, because of the increased exploration the discharges of water-based drill cuttings and muds have increased substantially, temporarily increasing water column sediment loads. The stony coral Lophelia pertusa is the most widely distributed and well-studied of the structure forming cold water corals (CWC) and it thrives in Norwegian waters where many reefs are located in the vicinity of oil platforms or exploration areas. This species provides habitat for a diverse and abundant assemblage of invertebrates and fishes, including commercially valuable species. High sediment loads are known to negatively affect adult corals, but impacts on the early life history stages are unknown. We investigated the effects of a range of drill cutting concentrations (0.5-640 ppm) on larvae of L. pertusa at ages five days and 15-20 days. One set of experiments was conducted in static experimental chambers that exposed larvae to decreasing concentrations over time, and the other maintained continuous drill cutting concentrations for the duration of the experiment (24 h). Increased sediment load for a duration of 24 h caused significant larval mortality, but there was an age-dependent difference in sensitivity of larvae. Younger larvae were significantly more susceptible to lower concentrations of drill cuttings than older larvae, while the older larvae were significantly more affected at higher concentrations. Five day old larvae were affected at treatment concentration 40 ppm. The larval cilia became clogged, preventing the larvae from swimming actively and ultimately causing mortality. Larvae of many species use cilia for swimming and feeding, so negative impacts of increased sediment may not be limited to corals.

High macroalgal cover and low coral recruitment undermines the potential resilience of the world's southernmost coral reef assemblages.

PubMed

Hoey, Andrew S; Pratchett, Morgan S; Cvitanovic, Christopher

2011-01-01

Coral reefs are under increasing pressure from anthropogenic and climate-induced stressors. The ability of reefs to reassemble and regenerate after disturbances (i.e., resilience) is largely dependent on the capacity of herbivores to prevent macroalgal expansion, and the replenishment of coral populations through larval recruitment. Currently there is a paucity of this information for higher latitude, subtropical reefs. To assess the potential resilience of the benthic reef assemblages of Lord Howe Island (31°32'S, 159°04'E), the worlds' southernmost coral reef, we quantified the benthic composition, densities of juvenile corals (as a proxy for coral recruitment), and herbivorous fish communities. Despite some variation among habitats and sites, benthic communities were dominated by live scleractinian corals (mean cover 37.4%) and fleshy macroalgae (20.9%). Live coral cover was higher than in most other subtropical reefs and directly comparable to lower latitude tropical reefs. Juvenile coral densities (0.8 ind.m(-2)), however, were 5-200 times lower than those reported for tropical reefs. Overall, macroalgal cover was negatively related to the cover of live coral and the density of juvenile corals, but displayed no relationship with herbivorous fish biomass. The biomass of herbivorous fishes was relatively low (204 kg.ha(-1)), and in marked contrast to tropical reefs was dominated by macroalgal browsing species (84.1%) with relatively few grazing species. Despite their extremely low biomass, grazing fishes were positively related to both the density of juvenile corals and the cover of bare substrata, suggesting that they may enhance the recruitment of corals through the provision of suitable settlement sites. Although Lord Howe Islands' reefs are currently coral-dominated, the high macroalgal cover, coupled with limited coral recruitment and low coral growth rates suggest these reefs may be extremely susceptible to future disturbances.

High Macroalgal Cover and Low Coral Recruitment Undermines the Potential Resilience of the World's Southernmost Coral Reef Assemblages

PubMed Central

Hoey, Andrew S.; Pratchett, Morgan S.; Cvitanovic, Christopher

2011-01-01

Coral reefs are under increasing pressure from anthropogenic and climate-induced stressors. The ability of reefs to reassemble and regenerate after disturbances (i.e., resilience) is largely dependent on the capacity of herbivores to prevent macroalgal expansion, and the replenishment of coral populations through larval recruitment. Currently there is a paucity of this information for higher latitude, subtropical reefs. To assess the potential resilience of the benthic reef assemblages of Lord Howe Island (31°32′S, 159°04′E), the worlds' southernmost coral reef, we quantified the benthic composition, densities of juvenile corals (as a proxy for coral recruitment), and herbivorous fish communities. Despite some variation among habitats and sites, benthic communities were dominated by live scleractinian corals (mean cover 37.4%) and fleshy macroalgae (20.9%). Live coral cover was higher than in most other subtropical reefs and directly comparable to lower latitude tropical reefs. Juvenile coral densities (0.8 ind.m−2), however, were 5–200 times lower than those reported for tropical reefs. Overall, macroalgal cover was negatively related to the cover of live coral and the density of juvenile corals, but displayed no relationship with herbivorous fish biomass. The biomass of herbivorous fishes was relatively low (204 kg.ha−1), and in marked contrast to tropical reefs was dominated by macroalgal browsing species (84.1%) with relatively few grazing species. Despite their extremely low biomass, grazing fishes were positively related to both the density of juvenile corals and the cover of bare substrata, suggesting that they may enhance the recruitment of corals through the provision of suitable settlement sites. Although Lord Howe Islands' reefs are currently coral-dominated, the high macroalgal cover, coupled with limited coral recruitment and low coral growth rates suggest these reefs may be extremely susceptible to future disturbances. PMID:21991366

The acute transcriptional response of the coral Acropora millepora to immune challenge: expression of GiMAP/IAN genes links the innate immune responses of corals with those of mammals and plants.

PubMed

Weiss, Yvonne; Forêt, Sylvain; Hayward, David C; Ainsworth, Tracy; King, Rob; Ball, Eldon E; Miller, David J

2013-06-14

As a step towards understanding coral immunity we present the first whole transcriptome analysis of the acute responses of Acropora millepora to challenge with the bacterial cell wall derivative MDP and the viral mimic poly I:C, defined immunogens provoking distinct but well characterised responses in higher animals. These experiments reveal similarities with the responses both of arthropods and mammals, as well as coral-specific effects. The most surprising finding was that MDP specifically induced three members of the GiMAP gene family, which has been implicated in immunity in mammals but is absent from Drosophila and Caenorhabditis. Like their mammalian homologs, GiMAP genes are arranged in a tandem cluster in the coral genome. A phylogenomic survey of this gene family implies ancient origins, multiple independent losses and lineage-specific expansions during animal evolution. Whilst functional convergence cannot be ruled out, GiMAP expression in corals may reflect an ancestral role in immunity, perhaps in phagolysosomal processing.

The Maritime Continent and Coral Triangle: How to make informed measurements in the year of the MC to improve coral protection?

NASA Astrophysics Data System (ADS)

Goodkin, N.; Tanzil, J.; Murty, S. A.; Ramos, R.; Pullen, J. D.

2016-12-01

The Maritime Continent (MC) is a region of highly complex oceanography, encompassing a majority of the Coral Triangle, the most important region for coral biodiversity and cover. Intricate coastal processes including water body mixing, resulting from reversing monsoon winds and internal waves, expose corals to a wide variety of physical conditions. However, the pressures of climate change, overfishing, ocean acidification, and coastal development, to name a few, are significant in this region and threaten to challenge reefs over the next several decades. In order to predict and study how to facilitate reef recovery in the MC region, it is crucial to understand the environmental parameters for coral success. In this presentation, we will provide an overview of oceanographic processes on the maritime continent that drive seasonal variability in the waters of the MC, including changes to sea surface temperature, salinity, pH, turbidity, productivity and nutrients. Each of these parameters is known to have impacts on calcification rates and thus coral reef formation. Environmental conditions and currents can combine to facilitate larval dispersion or to exacerbate coral disease and predation, including crown of thorns outbreaks. Internal waves may protect against coral bleaching by lowering temperatures with the delivery of deeper water. Drawing on previously published and unpublished results, we will evaluate the parameters that may be impacting reef growth rates, biodiversity and resilience in a changing world in an effort to help plan for key measurements in the year of the MC.

The future of coral reefs

NASA Astrophysics Data System (ADS)

Knowlton, Nancy

2001-05-01

Coral reefs, with their millions of species, have changed profoundly because of the effects of people, and will continue to do so for the foreseeable future. Reefs are subject to many of the same processes that affect other human-dominated ecosystems, but some special features merit emphasis: (i) Many dominant reef builders spawn eggs and sperm into the water column, where fertilization occurs. They are thus particularly vulnerable to Allee effects, including potential extinction associated with chronic reproductive failure. (ii) The corals likely to be most resistant to the effects of habitat degradation are small, short-lived "weedy" corals that have limited dispersal capabilities at the larval stage. Habitat degradation, together with habitat fragmentation, will therefore lead to the establishment of genetically isolated clusters of inbreeding corals. (iii) Increases in average sea temperatures by as little as 1°C, a likely result of global climate change, can cause coral "bleaching" (the breakdown of coral-algal symbiosis), changes in symbiont communities, and coral death. (iv) The activities of people near reefs increase both fishing pressure and nutrient inputs. In general, these processes favor more rapidly growing competitors, often fleshy seaweeds, and may also result in explosions of predator populations. (v) Combinations of stress appear to be associated with threshold responses and ecological surprises, including devastating pathogen outbreaks. (vi) The fossil record suggests that corals as a group are more likely to suffer extinctions than some of the groups that associate with them, whose habitat requirements may be less stringent.

Comparative genomics explains the evolutionary success of reef-forming corals

PubMed Central

Bhattacharya, Debashish; Agrawal, Shobhit; Aranda, Manuel; Baumgarten, Sebastian; Belcaid, Mahdi; Drake, Jeana L; Erwin, Douglas; Foret, Sylvian; Gates, Ruth D; Gruber, David F; Kamel, Bishoy; Lesser, Michael P; Levy, Oren; Liew, Yi Jin; MacManes, Matthew; Mass, Tali; Medina, Monica; Mehr, Shaadi; Meyer, Eli; Price, Dana C; Putnam, Hollie M; Qiu, Huan; Shinzato, Chuya; Shoguchi, Eiichi; Stokes, Alexander J; Tambutté, Sylvie; Tchernov, Dan; Voolstra, Christian R; Wagner, Nicole; Walker, Charles W; Weber, Andreas PM; Weis, Virginia; Zelzion, Ehud; Zoccola, Didier; Falkowski, Paul G

2016-01-01

Transcriptome and genome data from twenty stony coral species and a selection of reference bilaterians were studied to elucidate coral evolutionary history. We identified genes that encode the proteins responsible for the precipitation and aggregation of the aragonite skeleton on which the organisms live, and revealed a network of environmental sensors that coordinate responses of the host animals to temperature, light, and pH. Furthermore, we describe a variety of stress-related pathways, including apoptotic pathways that allow the host animals to detoxify reactive oxygen and nitrogen species that are generated by their intracellular photosynthetic symbionts, and determine the fate of corals under environmental stress. Some of these genes arose through horizontal gene transfer and comprise at least 0.2% of the animal gene inventory. Our analysis elucidates the evolutionary strategies that have allowed symbiotic corals to adapt and thrive for hundreds of millions of years. DOI: http://dx.doi.org/10.7554/eLife.13288.001 PMID:27218454

Oceanographic and behavioural assumptions in models of the fate of coral and coral reef fish larvae.

PubMed

Wolanski, Eric; Kingsford, Michael J

2014-09-06

A predictive model of the fate of coral reef fish larvae in a reef system is proposed that combines the oceanographic processes of advection and turbulent diffusion with the biological process of horizontal swimming controlled by olfactory and auditory cues within the timescales of larval development. In the model, auditory cues resulted in swimming towards the reefs when within hearing distance of the reef, whereas olfactory cues resulted in the larvae swimming towards the natal reef in open waters by swimming against the concentration gradients in the smell plume emanating from the natal reef. The model suggested that the self-seeding rate may be quite large, at least 20% for the larvae of rapidly developing reef fish species, which contrasted with a self-seeding rate less than 2% for non-swimming coral larvae. The predicted self-recruitment rate of reefs was sensitive to a number of parameters, such as the time at which the fish larvae reach post-flexion, the pelagic larval duration of the larvae, the horizontal turbulent diffusion coefficient in reefal waters and the horizontal swimming behaviour of the fish larvae in response to auditory and olfactory cues, for which better field data are needed. Thus, the model suggested that high self-seeding rates for reef fish are possible, even in areas where the 'sticky water' effect is minimal and in the absence of long-term trapping in oceanic fronts and/or large-scale oceanic eddies or filaments that are often argued to facilitate the return of the larvae after long periods of drifting at sea. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

The Importance of Coral Larval Recruitment for the Recovery of Reefs Impacted by Cyclone Yasi in the Central Great Barrier Reef

PubMed Central

Lukoschek, Vimoksalehi; Cross, Peter; Torda, Gergely; Zimmerman, Rachel; Willis, Bette L.

2013-01-01

Cyclone Yasi, one of the most severe tropical storms on record, crossed the central Great Barrier Reef (GBR) in February 2011, bringing wind speeds of up to 285 km hr−1 and wave heights of at least 10 m, and causing massive destruction to exposed reefs in the Palm Island Group. Following the cyclone, mean (± S.E.) hard coral cover ranged from just 2.1 (0.2) % to 5.3 (0.4) % on exposed reefs and no reproductively mature colonies of any species of Acropora remained. Although no fragments of Acropora were found at impacted exposed sites following the cyclone, small juvenile colonies of Acropora (<10 cm diameter) were present, suggesting that their small size and compact morphologies enabled them to survive the cyclone. By contrast, sheltered reefs appeared to be unaffected by the cyclone. Mean (± S.E.) hard coral cover ranged from 18.2 (2.4) % to 30.0 (1.0) % and a large proportion of colonies of Acropora were reproductively mature. Macroalgae accounted for 8 to 16% of benthic cover at exposed sites impacted by cyclone Yasi but were absent at sheltered sites. Mean (± S.E.) recruitment of acroporids to settlement tiles declined from 25.3 (4.8) recruits tile−1 in the pre-cyclone spawning event (2010) to 15.4 (2.2) recruits tile−1 in the first post-cyclone spawning event (2011). Yet, post-cyclone recruitment did not differ between exposed (15.2±2.1 S.E.) and sheltered sites (15.6±2.2 S.E.), despite the loss of reproductive colonies at the exposed sites, indicating larval input from external sources. Spatial variation in impacts, the survival of small colonies, and larval replenishment to impacted reefs suggest that populations of Acropora have the potential to recover from this severe disturbance, provided that the Palm Islands are not impacted by acute disturbances or suffer additional chronic stressors in the near future. PMID:23755223

The importance of coral larval recruitment for the recovery of reefs impacted by cyclone Yasi in the central Great Barrier Reef.

PubMed

Lukoschek, Vimoksalehi; Cross, Peter; Torda, Gergely; Zimmerman, Rachel; Willis, Bette L

2013-01-01

Cyclone Yasi, one of the most severe tropical storms on record, crossed the central Great Barrier Reef (GBR) in February 2011, bringing wind speeds of up to 285 km hr⁻¹ and wave heights of at least 10 m, and causing massive destruction to exposed reefs in the Palm Island Group. Following the cyclone, mean (± S.E.) hard coral cover ranged from just 2.1 (0.2) % to 5.3 (0.4) % on exposed reefs and no reproductively mature colonies of any species of Acropora remained. Although no fragments of Acropora were found at impacted exposed sites following the cyclone, small juvenile colonies of Acropora (<10 cm diameter) were present, suggesting that their small size and compact morphologies enabled them to survive the cyclone. By contrast, sheltered reefs appeared to be unaffected by the cyclone. Mean (± S.E.) hard coral cover ranged from 18.2 (2.4) % to 30.0 (1.0) % and a large proportion of colonies of Acropora were reproductively mature. Macroalgae accounted for 8 to 16% of benthic cover at exposed sites impacted by cyclone Yasi but were absent at sheltered sites. Mean (± S.E.) recruitment of acroporids to settlement tiles declined from 25.3 (4.8) recruits tile⁻¹ in the pre-cyclone spawning event (2010) to 15.4 (2.2) recruits tile⁻¹ in the first post-cyclone spawning event (2011). Yet, post-cyclone recruitment did not differ between exposed (15.2±2.1 S.E.) and sheltered sites (15.6±2.2 S.E.), despite the loss of reproductive colonies at the exposed sites, indicating larval input from external sources. Spatial variation in impacts, the survival of small colonies, and larval replenishment to impacted reefs suggest that populations of Acropora have the potential to recover from this severe disturbance, provided that the Palm Islands are not impacted by acute disturbances or suffer additional chronic stressors in the near future.

Settlement induction of Acropora palmata planulae by a GLW-amide neuropeptide

NASA Astrophysics Data System (ADS)

Erwin, P. M.; Szmant, A. M.

2010-12-01

Complex environmental cues dictate the settlement of coral planulae in situ; however, simple artificial cues may be all that is required to induce settlement of ex situ larval cultures for reef re-seeding and restoration projects. Neuropeptides that transmit settlement signals and initiate the metamorphic cascade have been isolated from hydrozoan taxa and shown to induce metamorphosis of reef-building Acropora spp. in the Indo-Pacific, providing a reliable and efficient settlement cue. Here, the metamorphic activity of six GLW-amide cnidarian neuropeptides was tested on larvae of the Caribbean corals Acropora palmata, Montastraea faveolata and Favia fragum. A. palmata planulae were induced to settle by the exogenous application of the neuropeptide Hym-248 (concentrations ≥1 × 10-6 M), achieving 40-80% attachment and 100% metamorphosis of competent planulae (≥6 days post-fertilization) during two spawning seasons; the remaining neuropeptides exhibited no activity. Hym-248 exposure rapidly altered larval swimming behavior (<1 h) and resulted in >96% metamorphosis after 6 h. In contrast , M. faveolata and F. fragum planulae did not respond to any GLW-amides tested, suggesting a high specificity of neuropeptide activators on lower taxonomic scales in corals. Subsequent experiments for A. palmata revealed that (1) the presence of a biofilm did not enhance attachment efficiency when coupled with Hym-248 treatment, (2) neuropeptide-induced settlement had no negative effects on early life-history developmental processes: zooxanthellae acquisition and skeletal secretion occurred within 12 days, colonial growth occurred within 36 days, and (3) Hym-248 solutions maintained metamorphic activity following storage at room temperature (10 days), indicating its utility in remote field settings. These results corroborate previous studies on Indo-Pacific Acropora spp. and extend the known metamorphic activity of Hym-248 to Caribbean acroporids. Hym-248 allows for directed and reliable settlement of larval cultures and has broad applications to the study and rehabilitation of threatened Acropora populations in the Caribbean.

Coral Settlement on a Highly Disturbed Equatorial Reef System

PubMed Central

Bauman, Andrew G.; Guest, James R.; Dunshea, Glenn; Low, Jeffery; Todd, Peter A.; Steinberg, Peter D.

2015-01-01

Processes occurring early in the life stages of corals can greatly influence the demography of coral populations, and successful settlement of coral larvae that leads to recruitment is a critical life history stage for coral reef ecosystems. Although corals in Singapore persist in one the world’s most anthropogenically impacted reef systems, our understanding of the role of coral settlement in the persistence of coral communities in Singapore remains limited. Spatial and temporal patterns of coral settlement were examined at 7 sites in the southern islands of Singapore, using settlement tiles deployed and collected every 3 months from 2011 to 2013. Settlement occurred year round, but varied significantly across time and space. Annual coral settlement was low (~54.72 spat m-2 yr-1) relative to other equatorial regions, but there was evidence of temporal variation in settlement rates. Peak settlement occurred between March–May and September–November, coinciding with annual coral spawning periods (March–April and October), while the lowest settlement occurred from December–February during the northeast monsoon. A period of high settlement was also observed between June and August in the first year (2011/12), possibly due to some species spawning outside predicted spawning periods, larvae settling from other locations or extended larval settlement competency periods. Settlement rates varied significantly among sites, but spatial variation was relatively consistent between years, suggesting the strong effects of local coral assemblages or environmental conditions. Pocilloporidae were the most abundant coral spat (83.6%), while Poritidae comprised only 6% of the spat, and Acroporidae <1%. Other, unidentifiable families represented 10% of the coral spat. These results indicate that current settlement patterns are reinforcing the local adult assemblage structure (‘others’; i.e. sediment-tolerant coral taxa) in Singapore, but that the replenishment capacity of Singapore’s reefs appears relatively constrained, which could lead to less resilient reefs. PMID:25992562

Spatial variation in abundance, size and orientation of juvenile corals related to the biomass of parrotfishes on the Great Barrier Reef, Australia.

PubMed

Trapon, Melanie L; Pratchett, Morgan S; Hoey, Andrew S

2013-01-01

For species with complex life histories such as scleractinian corals, processes occurring early in life can greatly influence the number of individuals entering the adult population. A plethora of studies have examined settlement patterns of coral larvae, mostly on artificial substrata, and the composition of adult corals across multiple spatial and temporal scales. However, relatively few studies have examined the spatial distribution of small (≤50 mm diameter) sexually immature corals on natural reef substrata. We, therefore, quantified the variation in the abundance, composition and size of juvenile corals (≤50 mm diameter) among 27 sites, nine reefs, and three latitudes spanning over 1000 km on Australia's Great Barrier Reef. Overall, 2801 juveniles were recorded with a mean density of 6.9 (±0.3 SE) ind.m(-2), with Acropora, Pocillopora, and Porites accounting for 84.1% of all juvenile corals surveyed. Size-class structure, orientation on the substrate and taxonomic composition of juvenile corals varied significantly among latitudinal sectors. The abundance of juvenile corals varied both within (6-13 ind.m(-2)) and among reefs (2.8-11.1 ind.m(-2)) but was fairly similar among latitudes (6.1-8.2 ind.m(-2)), despite marked latitudinal variation in larval supply and settlement rates previously found at this scale. Furthermore, the density of juvenile corals was negatively correlated with the biomass of scraping and excavating parrotfishes across all sites, revealing a potentially important role of parrotfishes in determining distribution patterns of juvenile corals on the Great Barrier Reef. While numerous studies have advocated the importance of parrotfishes for clearing space on the substrate to facilitate coral settlement, our results suggest that at high biomass they may have a detrimental effect on juvenile coral assemblages. There is, however, a clear need to directly quantify rates of mortality and growth of juvenile corals to understand the relative importance of these mechanisms in shaping juvenile, and consequently adult, coral assemblages.

Coral settlement on a highly disturbed equatorial reef system.

PubMed

Bauman, Andrew G; Guest, James R; Dunshea, Glenn; Low, Jeffery; Todd, Peter A; Steinberg, Peter D

2015-01-01

Processes occurring early in the life stages of corals can greatly influence the demography of coral populations, and successful settlement of coral larvae that leads to recruitment is a critical life history stage for coral reef ecosystems. Although corals in Singapore persist in one the world's most anthropogenically impacted reef systems, our understanding of the role of coral settlement in the persistence of coral communities in Singapore remains limited. Spatial and temporal patterns of coral settlement were examined at 7 sites in the southern islands of Singapore, using settlement tiles deployed and collected every 3 months from 2011 to 2013. Settlement occurred year round, but varied significantly across time and space. Annual coral settlement was low (~54.72 spat m(-2) yr(-1)) relative to other equatorial regions, but there was evidence of temporal variation in settlement rates. Peak settlement occurred between March-May and September-November, coinciding with annual coral spawning periods (March-April and October), while the lowest settlement occurred from December-February during the northeast monsoon. A period of high settlement was also observed between June and August in the first year (2011/12), possibly due to some species spawning outside predicted spawning periods, larvae settling from other locations or extended larval settlement competency periods. Settlement rates varied significantly among sites, but spatial variation was relatively consistent between years, suggesting the strong effects of local coral assemblages or environmental conditions. Pocilloporidae were the most abundant coral spat (83.6%), while Poritidae comprised only 6% of the spat, and Acroporidae <1%. Other, unidentifiable families represented 10% of the coral spat. These results indicate that current settlement patterns are reinforcing the local adult assemblage structure ('others'; i.e. sediment-tolerant coral taxa) in Singapore, but that the replenishment capacity of Singapore's reefs appears relatively constrained, which could lead to less resilient reefs.

Genomic basis for coral resilience to climate change.

PubMed

Barshis, Daniel J; Ladner, Jason T; Oliver, Thomas A; Seneca, François O; Traylor-Knowles, Nikki; Palumbi, Stephen R

2013-01-22

Recent advances in DNA-sequencing technologies now allow for in-depth characterization of the genomic stress responses of many organisms beyond model taxa. They are especially appropriate for organisms such as reef-building corals, for which dramatic declines in abundance are expected to worsen as anthropogenic climate change intensifies. Different corals differ substantially in physiological resilience to environmental stress, but the molecular mechanisms behind enhanced coral resilience remain unclear. Here, we compare transcriptome-wide gene expression (via RNA-Seq using Illumina sequencing) among conspecific thermally sensitive and thermally resilient corals to identify the molecular pathways contributing to coral resilience. Under simulated bleaching stress, sensitive and resilient corals change expression of hundreds of genes, but the resilient corals had higher expression under control conditions across 60 of these genes. These "frontloaded" transcripts were less up-regulated in resilient corals during heat stress and included thermal tolerance genes such as heat shock proteins and antioxidant enzymes, as well as a broad array of genes involved in apoptosis regulation, tumor suppression, innate immune response, and cell adhesion. We propose that constitutive frontloading enables an individual to maintain physiological resilience during frequently encountered environmental stress, an idea that has strong parallels in model systems such as yeast. Our study provides broad insight into the fundamental cellular processes responsible for enhanced stress tolerances that may enable some organisms to better persist into the future in an era of global climate change.

Small-Boat Noise Impacts Natural Settlement Behavior of Coral Reef Fish Larvae.

PubMed

Simpson, Stephen D; Radford, Andrew N; Holles, Sophie; Ferarri, Maud C O; Chivers, Douglas P; McCormick, Mark I; Meekan, Mark G

2016-01-01

After a pelagic larval phase, settlement-stage coral reef fish must locate a suitable reef habitat for juvenile life. Reef noise, produced by resident fish and invertebrates, provides an important cue for orientation and habitat selection during this process, which must often occur in environments impacted by anthropogenic noise. We adapted an established field-based protocol to test whether recorded boat noise influenced the settlement behavior of reef fish. Fewer fish settled to patch reefs broadcasting boat + reef noise compared with reef noise alone. This study suggests that boat noise, now a common feature of many reefs, can compromise critical settlement behavior of reef fishes.

High potential for formation and persistence of chimeras following aggregated larval settlement in the broadcast spawning coral, Acropora millepora

PubMed Central

Puill-Stephan, E.; van Oppen, M. J. H.; Pichavant-Rafini, K.; Willis, B. L.

2012-01-01

In sessile modular marine invertebrates, chimeras can originate from fusions of closely settling larvae or of colonies that come into contact through growth or movement. While it has been shown that juveniles of brooding corals fuse under experimental conditions, chimera formation in broadcast spawning corals, the most abundant group of reef corals, has not been examined. This study explores the capacity of the broadcast spawning coral Acropora millepora to form chimeras under experimental conditions and to persist as chimeras in the field. Under experimental conditions, 1.5-fold more larvae settled in aggregations than solitarily, and analyses of nine microsatellite loci revealed that 50 per cent of juveniles tested harboured different genotypes within the same colony. Significantly, some chimeric colonies persisted for 23 months post-settlement, when the study ended. Genotypes within persisting chimeric colonies all showed a high level of relatedness, whereas rejecting colonies displayed variable levels of relatedness. The nearly threefold greater sizes of chimeras compared with solitary juveniles, from settlement through to at least three months, suggest that chimerism is likely to be an important strategy for maximizing survival of vulnerable early life-history stages of corals, although longer-term studies are required to more fully explore the potential benefits of chimerism. PMID:21752820

High potential for formation and persistence of chimeras following aggregated larval settlement in the broadcast spawning coral, Acropora millepora.

PubMed

Puill-Stephan, E; van Oppen, M J H; Pichavant-Rafini, K; Willis, B L

2012-02-22

In sessile modular marine invertebrates, chimeras can originate from fusions of closely settling larvae or of colonies that come into contact through growth or movement. While it has been shown that juveniles of brooding corals fuse under experimental conditions, chimera formation in broadcast spawning corals, the most abundant group of reef corals, has not been examined. This study explores the capacity of the broadcast spawning coral Acropora millepora to form chimeras under experimental conditions and to persist as chimeras in the field. Under experimental conditions, 1.5-fold more larvae settled in aggregations than solitarily, and analyses of nine microsatellite loci revealed that 50 per cent of juveniles tested harboured different genotypes within the same colony. Significantly, some chimeric colonies persisted for 23 months post-settlement, when the study ended. Genotypes within persisting chimeric colonies all showed a high level of relatedness, whereas rejecting colonies displayed variable levels of relatedness. The nearly threefold greater sizes of chimeras compared with solitary juveniles, from settlement through to at least three months, suggest that chimerism is likely to be an important strategy for maximizing survival of vulnerable early life-history stages of corals, although longer-term studies are required to more fully explore the potential benefits of chimerism.

Climate change impacts on coral reefs: synergies with local effects, possibilities for acclimation, and management implications.

PubMed

Ateweberhan, Mebrahtu; Feary, David A; Keshavmurthy, Shashank; Chen, Allen; Schleyer, Michael H; Sheppard, Charles R C

2013-09-30

Most reviews concerning the impact of climate change on coral reefs discuss independent effects of warming or ocean acidification. However, the interactions between these, and between these and direct local stressors are less well addressed. This review underlines that coral bleaching, acidification, and diseases are expected to interact synergistically, and will negatively influence survival, growth, reproduction, larval development, settlement, and post-settlement development of corals. Interactions with local stress factors such as pollution, sedimentation, and overfishing are further expected to compound effects of climate change. Reduced coral cover and species composition following coral bleaching events affect coral reef fish community structure, with variable outcomes depending on their habitat dependence and trophic specialisation. Ocean acidification itself impacts fish mainly indirectly through disruption of predation- and habitat-associated behavior changes. Zooxanthellate octocorals on reefs are often overlooked but are substantial occupiers of space; these also are highly susceptible to bleaching but because they tend to be more heterotrophic, climate change impacts mainly manifest in terms of changes in species composition and population structure. Non-calcifying macroalgae are expected to respond positively to ocean acidification and promote microbe-induced coral mortality via the release of dissolved compounds, thus intensifying phase-shifts from coral to macroalgal domination. Adaptation of corals to these consequences of CO2 rise through increased tolerance of corals and successful mutualistic associations between corals and zooxanthellae is likely to be insufficient to match the rate and frequency of the projected changes. Impacts are interactive and magnified, and because there is a limited capacity for corals to adapt to climate change, global targets of carbon emission reductions are insufficient for coral reefs, so lower targets should be pursued. Alleviation of most local stress factors such as nutrient discharges, sedimentation, and overfishing is also imperative if sufficient overall resilience of reefs to climate change is to be achieved. Copyright © 2013 Elsevier Ltd. All rights reserved.

Differential gene expression during thermal stress and bleaching in the Caribbean coral Montastraea faveolata.

PubMed

DeSalvo, M K; Voolstra, C R; Sunagawa, S; Schwarz, J A; Stillman, J H; Coffroth, M A; Szmant, A M; Medina, M

2008-09-01

The declining health of coral reefs worldwide is likely to intensify in response to continued anthropogenic disturbance from coastal development, pollution, and climate change. In response to these stresses, reef-building corals may exhibit bleaching, which marks the breakdown in symbiosis between coral and zooxanthellae. Mass coral bleaching due to elevated water temperature can devastate coral reefs on a large geographical scale. In order to understand the molecular and cellular basis of bleaching in corals, we have measured gene expression changes associated with thermal stress and bleaching using a complementary DNA microarray containing 1310 genes of the Caribbean coral Montastraea faveolata. In a first experiment, we identified differentially expressed genes by comparing experimentally bleached M. faveolata fragments to control non-heat-stressed fragments. In a second experiment, we identified differentially expressed genes during a time course experiment with four time points across 9 days. Results suggest that thermal stress and bleaching in M. faveolata affect the following processes: oxidative stress, Ca(2+) homeostasis, cytoskeletal organization, cell death, calcification, metabolism, protein synthesis, heat shock protein activity, and transposon activity. These results represent the first medium-scale transcriptomic study focused on revealing the cellular foundation of thermal stress-induced coral bleaching. We postulate that oxidative stress in thermal-stressed corals causes a disruption of Ca(2+) homeostasis, which in turn leads to cytoskeletal and cell adhesion changes, decreased calcification, and the initiation of cell death via apoptosis and necrosis.

Habitat selection, facilitation, and biotic settlement cues affect distribution and performance of coral recruits in French Polynesia.

PubMed

Price, Nichole

2010-07-01

Habitat selection can determine the distribution and performance of individuals if the precision with which sites are chosen corresponds with exposure to risks or resources. Contrastingly, facilitation can allow persistence of individuals arriving by chance and potentially maladapted to local abiotic conditions. For marine organisms, selection of a permanent attachment site at the end of their larval stage or the presence of a facilitator can be a critical determinant of recruitment success. In coral reef ecosystems, it is well known that settling planula larvae of reef-building corals use coarse environmental cues (i.e., light) for habitat selection. Although laboratory studies suggest that larvae can also use precise biotic cues produced by crustose coralline algae (CCA) to select attachment sites, the ecological consequences of biotic cues for corals are poorly understood in situ. In a field experiment exploring the relative importance of biotic cues and variability in habitat quality to recruitment of hard corals, pocilloporid and acroporid corals recruited more frequently to one species of CCA, Titanoderma prototypum, and significantly less so to other species of CCA; these results are consistent with laboratory assays from other studies. The provision of the biotic cue accurately predicted coral recruitment rates across habitats of varying quality. At the scale of CCA, corals attached to the "preferred" CCA experienced increased survivorship while recruits attached elsewhere had lower colony growth and survivorship. For reef-building corals, the behavioral selection of habitat using chemical cues both reduces the risk of incidental mortality and indicates the presence of a facilitator.

Molecular reproductive characteristics of the reef coral Pocillopora damicornis.

PubMed

Rougée, Luc R A; Richmond, Robert H; Collier, Abby C

2015-11-01

Coral reefs are an indispensible worldwide resource, accounting for billions of dollars in cultural, economic, and ecological services. An understanding of coral reproduction is essential to determining the effects of environmental stressors on coral reef ecosystems and their persistence into the future. Here, we describe the presence of and changes in steroidal hormones along with associated steroidogenic and steroid removal enzymes during the reproductive cycle of the brooding, pan-Pacific, hermaphroditic coral, Pocillopora damicornis. Detectable levels of 17β-estradiol, estrone, progesterone and testosterone were consistently detected over two consecutive lunar reproductive cycles in coral tissue. Intra-colony variation in steroid hormone levels ranged between 1.5- and 2.2-fold and were not statistically different. Activities of the steroidogenic enzymes 3β-hydroxysteroid dehydrogenase and cytochrome P450 (CYP) 17 dehydrogenase were detectable and did not fluctuate over the reproductive cycle. Aromatase-like activity was detected during the lunar reproductive cycle with no significant fluctuations. Activities of regeneration enzymes did not fluctuate over the lunar cycle; however, activity of the clearance enzyme UDP-glucuronosyl transferases increased significantly (ANOVA, post hoc p<0.01) during the two weeks before and after peak larval release (planulation), suggesting that the activity of this enzyme family may be linked to the reproductive state of the coral. Sulfotransferase enzymes could not be detected. Our findings provide the first data defining normal physiological and lunar/reproductive variability in steroidal enzymes in a coral species with respect to their potential role in coral reproduction. Copyright © 2015 Elsevier Inc. All rights reserved.

Comparative analysis of the integument transcriptomes of the black dilute mutant and the wild-type silkworm Bombyx mori

PubMed Central

Wu, Songyuan; Tong, Xiaoling; Peng, Chenxing; Xiong, Gao; Lu, Kunpeng; hu, Hai; Tan, Duan; Li, Chunlin; Han, Minjin; Lu, Cheng; Dai, Fangyin

2016-01-01

The insect cuticle is a critical protective shell that is composed predominantly of chitin and various cuticular proteins and pigments. Indeed, insects often change their surface pigment patterns in response to selective pressures, such as threats from predators, sexual selection and environmental changes. However, the molecular mechanisms underlying the construction of the epidermis and its pigmentation patterns are not fully understood. Among Lepidoptera, the silkworm is a favorable model for color pattern research. The black dilute (bd) mutant of silkworm is the result of a spontaneous mutation; the larval body color is notably melanized. We performed integument transcriptome sequencing of the wild-type strain Dazao and the mutant strains +/bd and bd/bd. In these experiments, during an early stage of the fourth molt, a stage at which approximately 51% of genes were expressed genome wide (RPKM ≥1) in each strain. A total of 254 novel transcripts were characterized using Cuffcompare and BLAST analyses. Comparison of the transcriptome data revealed 28 differentially expressed genes (DEGs) that may contribute to bd larval melanism, including 15 cuticular protein genes that were remarkably highly expressed in the bd/bd mutant. We suggest that these significantly up-regulated cuticular proteins may promote melanism in silkworm larvae. PMID:27193628

Developmental Transcriptome of Aplysia californica

PubMed Central

HEYLAND, ANDREAS; VUE, ZER; VOOLSTRA, CHRISTIAN R.; MEDINA, MÓNICA; MOROZ, LEONID L.

2014-01-01

Genome-wide transcriptional changes in development provide important insight into mechanisms underlying growth, differentiation, and patterning. However, such large-scale developmental studies have been limited to a few representatives of Ecdysozoans and Chordates. Here, we characterize transcriptomes of embryonic, larval, and metamorphic development in the marine mollusc Aplysia californica and reveal novel molecular components associated with life history transitions. Specifically, we identify more than 20 signal peptides, putative hormones, and transcription factors in association with early development and metamorphic stages—many of which seem to be evolutionarily conserved elements of signal transduction pathways. We also characterize genes related to biomineralization—a critical process of molluscan development. In summary, our experiment provides the first large-scale survey of gene expression in mollusc development, and complements previous studies on the regulatory mechanisms underlying body plan patterning and the formation of larval and juvenile structures. This study serves as a resource for further functional annotation of transcripts and genes in Aplysia, specifically and molluscs in general. A comparison of the Aplysia developmental transcriptome with similar studies in the zebra fish Danio rerio, the fruit fly Drosophila melanogaster, the nematode Caenorhabditis elegans, and other studies on molluscs suggests an overall highly divergent pattern of gene regulatory mechanisms that are likely a consequence of the different developmental modes of these organisms. PMID:21328528

Species-area relationships in coral communities: evaluating mechanisms for a commonly observed pattern

NASA Astrophysics Data System (ADS)

Huntington, B. E.; Lirman, D.

2012-12-01

Landscape-scale attributes of patch size, spatial isolation, and topographic complexity are known to influence diversity and abundance in terrestrial and marine systems, but remain collectively untested for reef-building corals. To investigate the relationship between the coral assemblage and seascape variation in reef habitats, we took advantage of the distinct boundaries, spatial configurations, and topographic complexities among artificial reef patches to overcome the difficulties of manipulating natural reefs. Reef size (m2) was found to be the foremost predictor of coral richness in accordance with species-area relationship predictions. Larger reefs were also found to support significantly higher colony densities, enabling us to reject the null hypothesis of random placement (a sampling artifact) in favor of target area predictions that suggest greater rates of immigration on larger reefs. Unlike the pattern previously documented for reef fishes, topographic complexity was not a significant predictor of any coral assemblage response variable, despite the range of complexity values sampled. Lastly, coral colony density was best explained by both increasing reef size and decreasing reef spatial isolation, a pattern found exclusively among brooding species with shorter larval dispersal distances. We conclude that seascape attributes of reef size and spatial configuration within the seascape can influence the species richness and abundance of the coral community at relatively small spatial scales (<1 km). Specifically, we demonstrate how patterns in the coral communities that have naturally established on these manipulated reefs agree with the target area and island biogeography mechanisms to drive species-area relationships in reef-building corals. Based on the patterns documented in artificial reefs, habitat degradation that results in smaller, more isolated natural reefs may compromise coral diversity.

Metagenomic characterization of viral communities in corals: mining biological signal from methodological noise.

PubMed

Wood-Charlson, Elisha M; Weynberg, Karen D; Suttle, Curtis A; Roux, Simon; van Oppen, Madeleine J H

2015-10-01

Reef-building corals form close associations with organisms from all three domains of life and therefore have many potential viral hosts. Yet knowledge of viral communities associated with corals is barely explored. This complexity presents a number of challenges in terms of the metagenomic assessments of coral viral communities and requires specialized methods for purification and amplification of viral nucleic acids, as well as virome annotation. In this minireview, we conduct a meta-analysis of the limited number of existing coral virome studies, as well as available coral transcriptome and metagenome data, to identify trends and potential complications inherent in different methods. The analysis shows that the method used for viral nucleic acid isolation drastically affects the observed viral assemblage and interpretation of the results. Further, the small number of viral reference genomes available, coupled with short sequence read lengths might cause errors in virus identification. Despite these limitations and potential biases, the data show that viral communities associated with corals are diverse, with double- and single-stranded DNA and RNA viruses. The identified viruses are dominated by double-stranded DNA-tailed bacteriophages, but there are also viruses that infect eukaryote hosts, likely the endosymbiotic dinoflagellates, Symbiodinium spp., host coral and other eukaryotes in close association. © 2015 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

Transcriptome Analysis of the Scleractinian Coral Stylophora pistillata

PubMed Central

Salmon-Divon, Mali; Katzenellenbogen, Mark; Tambutté, Sylvie; Bertucci, Anthony; Hoegh-Guldberg, Ove; Deleury, Emeline; Allemand, Denis; Levy, Oren

2014-01-01

The principal architects of coral reefs are the scleractinian corals; these species are divided in two major clades referred to as “robust” and “complex” corals. Although the molecular diversity of the “complex” clade has received considerable attention, with several expressed sequence tag (EST) libraries and a complete genome sequence having been constructed, the “robust” corals have received far less attention, despite the fact that robust corals have been prominent focal points for ecological and physiological studies. Filling this gap affords important opportunities to extend these studies and to improve our understanding of the differences between the two major clades. Here, we present an EST library from Stylophora pistillata (Esper 1797) and systematically analyze the assembled transcripts compared to putative homologs from the complete proteomes of six well-characterized metazoans: Nematostella vectensis, Hydra magnipapillata, Caenorhabditis elegans, Drosophila melanogaster, Strongylocentrotus purpuratus, Ciona intestinalis and Homo sapiens. Furthermore, comparative analyses of the Stylophora pistillata ESTs were performed against several Cnidaria from the Scleractinia, Actiniaria and Hydrozoa, as well as against other stony corals separately. Functional characterization of S. pistillata transcripts into KOG/COG categories and further description of Wnt and bone morphogenetic protein (BMP) signaling pathways showed that the assembled EST library provides sufficient data and coverage. These features of this new library suggest considerable opportunities for extending our understanding of the molecular and physiological behavior of “robust” corals. PMID:24551124

Coral reef fish larvae settle close to home.

PubMed

Jones, Geoffrey P; Planes, Serge; Thorrold, Simon R

2005-07-26

Population connectivity through larval dispersal is an essential parameter in models of marine population dynamics and the optimal size and spacing of marine reserves. However, there are remarkably few direct estimates of larval dispersal for marine organisms, and the actual birth sites of successful recruits have never been located. Here, we solve the mystery of the natal origin of clownfish (Amphiprion polymnus) juveniles by mass-marking via tetracycline immersion all larvae produced in a population. In addition, we established parentage by DNA genotyping all potential adults and all new recruits arriving in the population. Although no individuals settled into the same anemone as their parents, many settled remarkably close to home. Even though this species has a 9-12 day larval duration, one-third of settled juveniles had returned to a 2 hectare natal area, with many settling <100 m from their birth site. This represents the smallest scale of dispersal known for any marine fish species with a pelagic larval phase. The degree of local retention indicates that marine reserves can provide recruitment benefits not only beyond but also within their boundaries.

Developmental Transcriptome Analysis and Identification of Genes Involved in Larval Metamorphosis of the Razor Clam, Sinonovacula constricta.

PubMed

Niu, Donghong; Wang, Fei; Xie, Shumei; Sun, Fanyue; Wang, Ze; Peng, Maoxiao; Li, Jiale

2016-04-01

The razor clam Sinonovacula constricta is an important commercial species. The deficiency of developmental transcriptomic data is becoming the bottleneck of further researches on the mechanisms underlying settlement and metamorphosis in early development. In this study, de novo transcriptome sequencing was performed for S. constricta at different early developmental stages by using Illumina HiSeq 2000 paired-end (PE) sequencing technology. A total of 112,209,077 PE clean reads were generated. De novo assembly generated 249,795 contigs with an average length of 585 bp. Gene annotation resulted in the identification of 22,870 unigene hits against the NCBI database. Eight unique sequences related to metamorphosis were identified and analyzed using real-time PCR. The razor clam reference transcriptome would provide useful information on early developmental and metamorphosis mechanisms and could be used in the genetic breeding of shellfish.

Complete genome sequence for the shellfish pathogen Vibrio coralliilyticus RE98 isolated from a shellfish hatchery

USDA-ARS?s Scientific Manuscript database

Vibrio coralliilyticus is a pathogen of corals and larval shellfish. Publications on strain RE98 list it as a Vibrio tubiashii; however, whole genome sequencing confirms RE98 as V. coralliilyticus containing a total of 6,037,824 bp consisting of two chromosomes (3,420,228 and 1,917,482 bp), and two...

Development and Symbiosis Establishment in the Cnidarian Endosymbiosis Model Aiptasia sp.

PubMed Central

Bucher, Madeline; Wolfowicz, Iliona; Voss, Philipp A.; Hambleton, Elizabeth A.; Guse, Annika

2016-01-01

Symbiosis between photosynthetic algae and heterotrophic organisms is widespread. One prominent example of high ecological relevance is the endosymbiosis between dinoflagellate algae of the genus Symbiodinium and reef-building corals, which typically acquire symbionts anew each generation during larval stages. The tropical sea anemone Aiptasia sp. is a laboratory model system for this endosymbiosis and, similar to corals, produces non-symbiotic larvae that establish symbiosis by phagocytosing Symbiodinium from the environment into the endoderm. Here we generate the first overview of Aiptasia embryogenesis and larval development and establish in situ hybridization to analyze expression patterns of key early developmental regulators. Next, we quantify morphological changes in developing larvae and find a substantial enlargement of the gastric cavity over time. Symbiont acquisition starts soon after mouth formation and symbionts occupy a major portion of the host cell in which they reside. During the first 14 days of development, infection efficiency remains constant while in contrast, localization of phagocytosed symbionts changes, indicating that the occurrence of functional phagocytosing cells may be developmentally regulated. Taken together, here we provide the essential framework to further develop Aiptasia as a model system for the analysis of symbiosis establishment in cnidarian larvae at the molecular level. PMID:26804034

Development and Symbiosis Establishment in the Cnidarian Endosymbiosis Model Aiptasia sp.

PubMed

Bucher, Madeline; Wolfowicz, Iliona; Voss, Philipp A; Hambleton, Elizabeth A; Guse, Annika

2016-01-25

Symbiosis between photosynthetic algae and heterotrophic organisms is widespread. One prominent example of high ecological relevance is the endosymbiosis between dinoflagellate algae of the genus Symbiodinium and reef-building corals, which typically acquire symbionts anew each generation during larval stages. The tropical sea anemone Aiptasia sp. is a laboratory model system for this endosymbiosis and, similar to corals, produces non-symbiotic larvae that establish symbiosis by phagocytosing Symbiodinium from the environment into the endoderm. Here we generate the first overview of Aiptasia embryogenesis and larval development and establish in situ hybridization to analyze expression patterns of key early developmental regulators. Next, we quantify morphological changes in developing larvae and find a substantial enlargement of the gastric cavity over time. Symbiont acquisition starts soon after mouth formation and symbionts occupy a major portion of the host cell in which they reside. During the first 14 days of development, infection efficiency remains constant while in contrast, localization of phagocytosed symbionts changes, indicating that the occurrence of functional phagocytosing cells may be developmentally regulated. Taken together, here we provide the essential framework to further develop Aiptasia as a model system for the analysis of symbiosis establishment in cnidarian larvae at the molecular level.

Potential and limits for rapid genetic adaptation to warming in a Great Barrier Reef coral.

PubMed

Matz, Mikhail V; Treml, Eric A; Aglyamova, Galina V; Bay, Line K

2018-04-01

Can genetic adaptation in reef-building corals keep pace with the current rate of sea surface warming? Here we combine population genomics, biophysical modeling, and evolutionary simulations to predict future adaptation of the common coral Acropora millepora on the Great Barrier Reef (GBR). Genomics-derived migration rates were high (0.1-1% of immigrants per generation across half the latitudinal range of the GBR) and closely matched the biophysical model of larval dispersal. Both genetic and biophysical models indicated the prevalence of southward migration along the GBR that would facilitate the spread of heat-tolerant alleles to higher latitudes as the climate warms. We developed an individual-based metapopulation model of polygenic adaptation and parameterized it with population sizes and migration rates derived from the genomic analysis. We find that high migration rates do not disrupt local thermal adaptation, and that the resulting standing genetic variation should be sufficient to fuel rapid region-wide adaptation of A. millepora populations to gradual warming over the next 20-50 coral generations (100-250 years). Further adaptation based on novel mutations might also be possible, but this depends on the currently unknown genetic parameters underlying coral thermal tolerance and the rate of warming realized. Despite this capacity for adaptation, our model predicts that coral populations would become increasingly sensitive to random thermal fluctuations such as ENSO cycles or heat waves, which corresponds well with the recent increase in frequency of catastrophic coral bleaching events.

Mechanisms for eco-immunity in a changing enviroment: how does the coral innate immune system contend with climate change?

NASA Astrophysics Data System (ADS)

Traylor-Knowles, N. G.

2016-02-01

Innate immunity plays a central role in maintaining homeostasis, and within the context of impending climate change scenarios, understanding how this system works is critical. However, the actual mechanisms involved in the evolution of the innate immune system are largely unknown. Cnidaria (including corals, sea anemones and jellyfish) are well suited for studying the fundamental functions of innate immunity because they share a common ancestor with bilaterians. This study will highlight the transcriptomic changes during a heat shock in the coral Acropora hyacinthus of American Samoa, examining the temporal changes, every half an hour for 5 hours. We hypothesize that genes involved in innate immunity, and extracellular matrix maintenance will be key components to the heat stress response. This presentation will highlight the novel role of the tumor necrosis factor receptor gene family as a responder to heat stress and present future directions for this developing field in coral reef research.

The non-linear relationship between body size and function in parrotfishes

NASA Astrophysics Data System (ADS)

Lokrantz, J.; Nyström, M.; Thyresson, M.; Johansson, C.

2008-12-01

Parrotfishes are a group of herbivores that play an important functional role in structuring benthic communities on coral reefs. Increasingly, these fish are being targeted by fishermen, and resultant declines in biomass and abundance may have severe consequences for the dynamics and regeneration of coral reefs. However, the impact of overfishing extends beyond declining fish stocks. It can also lead to demographic changes within species populations where mean body size is reduced. The effect of reduced mean body size on population dynamics is well described in literature but virtually no information exists on how this may influence important ecological functions. The study investigated how one important function, scraping (i.e., the capacity to remove algae and open up bare substratum for coral larval settlement), by three common species of parrotfishes ( Scarus niger, Chlorurus sordidus, and Chlorurus strongylocephalus) on coral reefs at Zanzibar (Tanzania) was influenced by the size of individual fishes. There was a non-linear relationship between body size and scraping function for all species examined, and impact through scraping was also found to increase markedly when fish reached a size of 15 20 cm. Thus, coral reefs which have a high abundance and biomass of parrotfish may nonetheless be functionally impaired if dominated by small-sized individuals. Reductions in mean body size within parrotfish populations could, therefore, have functional impacts on coral reefs that previously have been overlooked.

Coral recruitment and recovery after the 2004 Tsunami around the Phi Phi Islands (Krabi Province) and Phuket, Andaman Sea, Thailand

NASA Astrophysics Data System (ADS)

Sawall, Y.; Phongsuwan, N.; Richter, C.

2010-12-01

The 2004 tsunami left a discontinuous pattern of destruction in the reefs along Andaman Sea coast of Thailand. Here, a comparative assessment of coral recruitment was carried out to assess differences in recovery between damaged and undamaged sites in near-shore fringing reefs 1 and 3 years after the tsunami. Settlement plates showed high frequencies of coral spat after 4 months (<17 spat tile-1) in both, damaged and undamaged locations. Field surveys carried out 3 years after the tsunami on natural substrate confirmed that tsunami damage did not suppress recruitment in damaged sites relative to no impacted controls. New and stable settlement space along with unabated larval supply supported post-tsunami recruit densities up to 7.2 m-2 year-1. Mean recruit densities were found at the level of post-storm situations with rapid recovery success, suggesting that the duration of disturbance, degree of sorting and, hence, stability of coral rubble is a key determinant of recruitment success. Low regeneration success of some species e.g. branching acroporids and rebounding tourism industry at sites like Patong and partly around the Phi Phi Islands (dense carpets of filamentous algae) led to the assumption of selectivity and eventually to an alternation of the coral community even though live coral cover might be recovered soon.

Modeling fine-scale coral larval dispersal and interisland connectivity to help designate mutually-supporting coral reef marine protected areas: Insights from Maui Nui, Hawaii

USGS Publications Warehouse

Storlazzi, Curt; van Ormondt, Maarten; Chen, Yi-Leng; Elias, Edwin P. L.

2017-01-01

Connectivity among individual marine protected areas (MPAs) is one of the most important considerations in the design of integrated MPA networks. To provide such information for managers in Hawaii, USA, a numerical circulation model was developed to determine the role of ocean currents in transporting coral larvae from natal reefs throughout the high volcanic islands of the Maui Nui island complex in the southeastern Hawaiian Archipelago. Spatially- and temporally-varying wind, wave, and circulation model outputs were used to drive a km-scale, 3-dimensional, physics-based circulation model for Maui Nui. The model was calibrated and validated using satellite-tracked ocean surface current drifters deployed during coral-spawning conditions, then used to simulate the movement of the larvae of the dominant reef-building coral, Porites compressa, from 17 reefs during eight spawning events in 2010–2013. These simulations make it possible to investigate not only the general dispersal patterns from individual coral reefs, but also how anomalous conditions during individual spawning events can result in large deviations from those general patterns. These data also help identify those reefs that are dominated by self-seeding and those where self-seeding is limited to determine their relative susceptibility to stressors and potential roadblocks to recovery. Overall, the numerical model results indicate that many of the coral reefs in Maui Nui seed reefs on adjacent islands, demonstrating the interconnected nature of the coral reefs in Maui Nui and providing a key component of the scientific underpinning essential for the design of a mutually supportive network of MPAs to enhance conservation of coral reefs.

Allelochemicals Produced by Brown Macroalgae of the Lobophora Genus Are Active against Coral Larvae and Associated Bacteria, Supporting Pathogenic Shifts to Vibrio Dominance

PubMed Central

Bromhall, Katrina; Motti, Cherie A.; Munn, Colin B.; Bourne, David G.

2016-01-01

ABSTRACT Pervasive environmental stressors on coral reefs are attributed with shifting the competitive balance in favor of alternative dominants, such as macroalgae. Previous studies have demonstrated that macroalgae compete with corals via a number of mechanisms, including the production of potent primary and secondary metabolites that can influence coral-associated microbial communities. The present study investigates the effects of the Pacific brown macroalga Lobophora sp. (due to the shifting nature of the Lobophora species complex, it will be referred to here as Lobophora sp.) on coral bacterial isolates, coral larvae, and the microbiome associated with the coral Porites cylindrica. Crude aqueous and organic macroalgal extracts were found to inhibit the growth of coral-associated bacteria. Extracts and fractions were also shown to inhibit coral larval settlement and cause mortality at concentrations lower (<0.3 mg · ml−1) than calculated natural concentrations (4.4 mg · ml−1). Microbial communities associated with coral tissues exposed to aqueous (e.g., hydrophilic) crude extracts demonstrated a significant shift to Vibrio dominance and a loss of sequences related to the putative coral bacterial symbiont, Endozoicomonas sp., based on 16S rRNA amplicon sequencing. This study contributes to growing evidence that macroalgal allelochemicals, dissolved organic material, and native macroalgal microbial assemblages all play a role in shifting the microbial equilibrium of the coral holobiont away from a beneficial state, contributing to a decline in coral fitness and a shift in ecosystem structure. IMPORTANCE Diverse microbial communities associate with coral tissues and mucus, providing important protective and nutritional services, but once disturbed, the microbial equilibrium may shift from a beneficial state to one that is detrimental or pathogenic. Macroalgae (e.g., seaweeds) can physically and chemically interact with corals, causing abrasion, bleaching, and overall stress. This study contributes to a growing body of evidence suggesting that macroalgae play a critical role in shifting the coral holobiont equilibrium, which may promote the invasion of opportunistic pathogens and cause coral mortality, facilitating additional macroalgal growth and invasion in the reef. Thus, macroalgae not only contribute to a decline in coral fitness but also influence coral reef ecosystem structure. PMID:27795310

Allelochemicals Produced by Brown Macroalgae of the Lobophora Genus Are Active against Coral Larvae and Associated Bacteria, Supporting Pathogenic Shifts to Vibrio Dominance.

PubMed

Morrow, Kathleen M; Bromhall, Katrina; Motti, Cherie A; Munn, Colin B; Bourne, David G

2017-01-01

Pervasive environmental stressors on coral reefs are attributed with shifting the competitive balance in favor of alternative dominants, such as macroalgae. Previous studies have demonstrated that macroalgae compete with corals via a number of mechanisms, including the production of potent primary and secondary metabolites that can influence coral-associated microbial communities. The present study investigates the effects of the Pacific brown macroalga Lobophora sp. (due to the shifting nature of the Lobophora species complex, it will be referred to here as Lobophora sp.) on coral bacterial isolates, coral larvae, and the microbiome associated with the coral Porites cylindrica. Crude aqueous and organic macroalgal extracts were found to inhibit the growth of coral-associated bacteria. Extracts and fractions were also shown to inhibit coral larval settlement and cause mortality at concentrations lower (<0.3 mg · ml -1 ) than calculated natural concentrations (4.4 mg · ml -1 ). Microbial communities associated with coral tissues exposed to aqueous (e.g., hydrophilic) crude extracts demonstrated a significant shift to Vibrio dominance and a loss of sequences related to the putative coral bacterial symbiont, Endozoicomonas sp., based on 16S rRNA amplicon sequencing. This study contributes to growing evidence that macroalgal allelochemicals, dissolved organic material, and native macroalgal microbial assemblages all play a role in shifting the microbial equilibrium of the coral holobiont away from a beneficial state, contributing to a decline in coral fitness and a shift in ecosystem structure. Diverse microbial communities associate with coral tissues and mucus, providing important protective and nutritional services, but once disturbed, the microbial equilibrium may shift from a beneficial state to one that is detrimental or pathogenic. Macroalgae (e.g., seaweeds) can physically and chemically interact with corals, causing abrasion, bleaching, and overall stress. This study contributes to a growing body of evidence suggesting that macroalgae play a critical role in shifting the coral holobiont equilibrium, which may promote the invasion of opportunistic pathogens and cause coral mortality, facilitating additional macroalgal growth and invasion in the reef. Thus, macroalgae not only contribute to a decline in coral fitness but also influence coral reef ecosystem structure. © Crown copyright 2016.

Similar specificities of symbiont uptake by adults and larvae in an anemone model system for coral biology

PubMed Central

Hambleton, Elizabeth A.; Guse, Annika; Pringle, John R.

2014-01-01

Reef-building corals depend for much of their energy on photosynthesis by symbiotic dinoflagellate algae (genus Symbiodinium) that live within their gastrodermal cells. However, the cellular mechanisms underpinning this ecologically critical symbiosis, including those governing the specificity of symbiont uptake by the host, remain poorly understood, in part because of the difficulties of working with corals in the laboratory. Here, we used the small symbiotic sea anemone Aiptasia as an experimentally tractable model system to analyze the specificity and timing of symbiosis onset in larval and adult animals under controlled laboratory conditions. Using four clonal, axenic Symbiodinium strains, we found no difference in uptake specificity between larvae (even when very young) and adults. Although both compatible and incompatible algal strains were found within the larval guts, only the former appeared to be internalized by gastrodermal cells, and they (but not incompatible algae) proliferated rapidly within the larvae in the absence of detectable exchange with other larvae. Older larvae showed reduced ingestion of both compatible and incompatible algae, and the addition of food failed to promote the uptake of an incompatible algal strain. Thus, Aiptasia adults and larvae appear to have similar mechanisms for discriminating between compatible and incompatible dinoflagellate types prior to phagocytosis by host gastrodermal cells. Whether a particular algal strain is compatible or incompatible appears to be stable during years of axenic culture in the absence of a host. These studies provide a foundation for future analyses of the mechanisms of symbiont-uptake specificity in this emerging model system. PMID:24526722

Analysis of nitric oxide-cyclic guanosine monophosphate signaling during metamorphosis of the nudibranch Phestilla sibogae Bergh (Gastropoda: Opisthobranchia)

PubMed Central

Bishop, Cory D.; Pires, Anthony; Norby, Shong-Wan; Boudko, Dmitri; Moroz, Leonid L.; Hadfield, Michael G.

2014-01-01

SUMMARY The gas nitric oxide (NO), and in some cases its downstream second messenger, cyclic guanosine monophosphate (cGMP) function in different taxa to regulate the timing of life-history transitions. Increased taxonomic sampling is required to foster conclusions about the evolution and function of NO/cGMP signaling during life-history transitions. We report on the function and localization of NO and cGMP signaling during metamorphosis of the nudibranch Phestilla sibogae. Pharmacological manipulation of NO or cGMP production in larvae modulated responses to a natural settlement cue from the coral Porites compressa in a manner that suggest inhibitory function for NO/cGMP signaling. However, these treatments were not sufficient to induce metamorphosis in the absence of cue, a result unique to this animal. We show that induction of metamorphosis in response to the settlement cue is associated with a reduction in NO production. We documented the expression of putative NO synthase (NOS) and the production of cGMP during larval development and observed no larval cells in which NOS and cGMP were both detected. The production of cGMP in a bilaterally symmetrical group of cells fated to occupy the distal tip of rhinophores is correlated with competence to respond to the coral settlement cue. These results suggest that endogenous NO and cGMP are involved in modulating responses of P. sibogae to a natural settlement cue. We discuss these results with respect to habitat selection and larval ecology. PMID:18460091

Developmental Progression in the Coral Acropora digitifera Is Controlled by Differential Expression of Distinct Regulatory Gene Networks

PubMed Central

Reyes-Bermudez, Alejandro; Villar-Briones, Alejandro; Ramirez-Portilla, Catalina; Hidaka, Michio; Mikheyev, Alexander S.

2016-01-01

Corals belong to the most basal class of the Phylum Cnidaria, which is considered the sister group of bilaterian animals, and thus have become an emerging model to study the evolution of developmental mechanisms. Although cell renewal, differentiation, and maintenance of pluripotency are cellular events shared by multicellular animals, the cellular basis of these fundamental biological processes are still poorly understood. To understand how changes in gene expression regulate morphogenetic transitions at the base of the eumetazoa, we performed quantitative RNA-seq analysis during Acropora digitifera’s development. We collected embryonic, larval, and adult samples to characterize stage-specific transcription profiles, as well as broad expression patterns. Transcription profiles reconstructed development revealing two main expression clusters. The first cluster grouped blastula and gastrula and the second grouped subsequent developmental time points. Consistently, we observed clear differences in gene expression between early and late developmental transitions, with higher numbers of differentially expressed genes and fold changes around gastrulation. Furthermore, we identified three coexpression clusters that represented discrete gene expression patterns. During early transitions, transcriptional networks seemed to regulate cellular fate and morphogenesis of the larval body. In late transitions, these networks seemed to play important roles preparing planulae for switch in lifestyle and regulation of adult processes. Although developmental progression in A. digitifera is regulated to some extent by differential coexpression of well-defined gene networks, stage-specific transcription profiles appear to be independent entities. While negative regulation of transcription is predominant in early development, cell differentiation was upregulated in larval and adult stages. PMID:26941230

Evidence for Multiple Phototransduction Pathways in a Reef-Building Coral

PubMed Central

Mason, Benjamin; Schmale, Michael; Gibbs, Patrick; Miller, Margaret W.; Wang, Qiang; Levay, Konstantin; Shestopalov, Valery; Slepak, Vladlen Z.

2012-01-01

Photosensitive behaviors and circadian rhythms are well documented in reef-building corals and their larvae, but the mechanisms responsible for photoreception have not been described in these organisms. Here we report the cloning, immunolocalization, and partial biochemical characterization of three opsins and four G proteins expressed in planulae of the Caribbean elkhorn coral, Acropora palmata. All three opsins (acropsins 1–3) possess conserved seven-pass transmembrane structure, and localize to distinct regions of coral planulae. Acropsin 1 was localized in the larval endoderm, while acropsin 2 was localized in solitary cells of the ectoderm. These rod-like cells displayed a remarkably polarized distribution, concentrated in the aboral end. We also cloned four A. palmata G protein alpha subunits. Three were homologs of vertebrate Gi, Go, and Gq. The fourth is presumably a novel G protein, which displays only 40% identity with the nearest known G protein, and we termed it Gc for “cnidarian”. We show that Gc and Gq can be activated by acropsins in a light-dependent manner in vitro. This indicates that at least acropsins 1 and 3 can form functional photoreceptors and potentially may play a role in color preference during settlement, vertical positioning and other light-guided behaviors observed in coral larvae. PMID:23227169

Habitat degradation disrupts neophobia in juvenile coral reef fish.

PubMed

McCormick, Mark I; Chivers, Douglas P; Allan, Bridie J M; Ferrari, Maud C O

2017-02-01

Habitat degradation not only disrupts habitat-forming species, but alters the sensory landscape within which most species must balance behavioural activities against predation risk. Rapidly developing a cautious behavioural phenotype, a condition known as neophobia, is advantageous when entering a novel risky habitat. Many aquatic organisms rely on damage-released conspecific cues (i.e. alarm cues) as an indicator of impending danger and use them to assess general risk and develop neophobia. This study tested whether settlement-stage damselfish associated with degraded coral reef habitats were able to use alarm cues as an indicator of risk and, in turn, develop a neophobic response at the end of their larval phase. Our results indicate that fish in live coral habitats that were exposed to alarm cues developed neophobia, and, in situ, were found to be more cautious, more closely associated with their coral shelters and survived four-times better than non-neophobic control fish. In contrast, fish that settled onto degraded coral habitats did not exhibit neophobia and consequently suffered much greater mortality on the reef, regardless of their history of exposure to alarm cues. Our results show that habitat degradation alters the efficacy of alarm cues with phenotypic and survival consequences for newly settled recruits. © 2016 John Wiley & Sons Ltd.

De novo metatranscriptome assembly and coral gene expression profile of Montipora capitata with growth anomaly.

PubMed

Frazier, Monika; Helmkampf, Martin; Bellinger, M Renee; Geib, Scott M; Takabayashi, Misaki

2017-09-11

Scleractinian corals are a vital component of coral reef ecosystems, and of significant cultural and economic value worldwide. As anthropogenic and natural stressors are contributing to a global decline of coral reefs, understanding coral health is critical to help preserve these ecosystems. Growth anomaly (GA) is a coral disease that has significant negative impacts on coral biology, yet our understanding of its etiology and pathology is lacking. In this study we used RNA-seq along with de novo metatranscriptome assembly and homology assignment to identify coral genes that are expressed in three distinct coral tissue types: tissue from healthy corals ("healthy"), GA lesion tissue from diseased corals ("GA-affected") and apparently healthy tissue from diseased corals ("GA-unaffected"). We conducted pairwise comparisons of gene expression among these three tissue types to identify genes and pathways that help us to unravel the molecular pathology of this coral disease. The quality-filtered de novo-assembled metatranscriptome contained 76,063 genes, of which 13,643 were identified as putative coral genes. Overall gene expression profiles of coral genes revealed high similarity between healthy tissue samples, in contrast to high variance among diseased samples. This indicates GA has a variety of genetic effects at the colony level, including on seemingly healthy (GA-unaffected) tissue. A total of 105 unique coral genes were found differentially expressed among tissue types. Pairwise comparisons revealed the greatest number of differentially expressed genes between healthy and GA-affected tissue (93 genes), followed by healthy and GA-unaffected tissue (33 genes), and GA-affected and -unaffected tissue (7 genes). The putative function of these genes suggests GA is associated with changes in the activity of genes involved in developmental processes and activation of the immune system. This is one of the first transcriptome-level studies to investigate coral GA, and the first metatranscriptome assembly for the M. capitata holobiont. The gene expression data, metatranscriptome assembly and methodology developed through this study represent a significant addition to the molecular information available to further our understanding of this coral disease.

Transcriptomic Analysis of Differentially Expressed Genes During Larval Development of Rapana venosa by Digital Gene Expression Profiling.

PubMed

Song, Hao; Yu, Zheng-Lin; Sun, Li-Na; Xue, Dong-Xiu; Zhang, Tao; Wang, Hai-Yan

2016-07-07

During the life cycle of shellfish, larval development, especially metamorphosis, has a vital influence on the dynamics, distribution, and recruitment of natural populations, as well as seed breeding. Rapana venosa, a carnivorous gastropod, is an important commercial shellfish in China, and is an ecological invader in the United States, Argentina, and France. However, information about the mechanism of its early development is still limited, because research in this area has long suffered from a lack of genomic resources. In this study, 15 digital gene expression (DGE) libraries from five developmental stages of R. venosa were constructed and sequenced on the IIIumina Hi-Sequation 2500 platform. Bioinformaticsanalysis identified numerous differentially and specifically expressed genes, which revealed that genes associated with growth, nervous system, digestive system, immune system, and apoptosis participate in important developmental processes. The functional analysis of differentially expressed genes was further implemented by gene ontology, and Kyoto encyclopedia of genes and genomes enrichment. DGE profiling provided a general picture of the transcriptomic activities during the early development of R. venosa, which may provide interesting hints for further study. Our data represent the first comparative transcriptomic information available for the early development of R. venosa, which is a prerequisite for a better understanding of the physiological traits controlling development. Copyright © 2016 Song et al.

Small Marine Protected Areas in Fiji Provide Refuge for Reef Fish Assemblages, Feeding Groups, and Corals.

PubMed

Bonaldo, Roberta M; Pires, Mathias M; Guimarães, Paulo Roberto; Hoey, Andrew S; Hay, Mark E

2017-01-01

The establishment of no-take marine protected areas (MPAs) on coral reefs is a common management strategy for conserving the diversity, abundance, and biomass of reef organisms. Generally, well-managed and enforced MPAs can increase or maintain the diversity and function of the enclosed coral reef, with some of the benefits extending to adjacent non-protected reefs. A fundamental question in coral reef conservation is whether these benefits arise within small MPAs (<1 km2), because larval input of reef organisms is largely decoupled from local adult reproduction. We examined the structure of fish assemblages, composition of fish feeding groups, benthic cover, and key ecosystem processes (grazing, macroalgal browsing, and coral replenishment) in three small (0.5-0.8 km2) no-take MPAs and adjacent areas where fisheries are allowed (non-MPAs) on coral reefs in Fiji. The MPAs exhibited greater species richness, density, and biomass of fishes than non-MPAs. Furthermore, MPAs contained a greater abundance and biomass of grazing herbivores and piscivores as well as a greater abundance of cleaners than fished areas. We also found differences in fish associations when foraging, with feeding groups being generally more diverse and having greater biomass within MPAs than adjacent non-MPAs. Grazing by parrotfishes was 3-6 times greater, and macroalgal browsing was 3-5 times greater in MPAs than in non-MPAs. On average, MPAs had 260-280% as much coral cover and only 5-25% as much macroalgal cover as their paired non-MPA sites. Finally, two of the three MPAs had three-fold more coral recruits than adjacent non-MPAs. The results of this study indicate that small MPAs benefit not only populations of reef fishes, but also enhance ecosystem processes that are critical to reef resilience within the MPAs.

Exploring the role of Micronesian islands in the maintenance of coral genetic diversity in the Pacific Ocean.

PubMed

Davies, S W; Treml, E A; Kenkel, C D; Matz, M V

2015-01-01

Understanding how genetic diversity is maintained across patchy marine environments remains a fundamental problem in marine biology. The Coral Triangle, located in the Indo-West Pacific, is the centre of marine biodiversity and has been proposed as an important source of genetic diversity for remote Pacific reefs. Several studies highlight Micronesia, a scattering of hundreds of small islands situated within the North Equatorial Counter Current, as a potentially important migration corridor. To test this hypothesis, we characterized the population genetic structure of two ecologically important congeneric species of reef-building corals across greater Micronesia, from Palau to the Marshall Islands. Genetic divergences between islands followed an isolation-by-distance pattern, with Acropora hyacinthus exhibiting greater genetic divergences than A. digitifera, suggesting different migration capabilities or different effective population sizes for these closely related species. We inferred dispersal distance using a biophysical larval transport model, which explained an additional 15-21% of the observed genetic variation compared to between-island geographical distance alone. For both species, genetic divergence accumulates and genetic diversity diminishes with distance from the Coral Triangle, supporting the hypothesis that Micronesian islands act as important stepping stones connecting the central Pacific with the species-rich Coral Triangle. However, for A. hyacinthus, the species with lower genetic connectivity, immigration from the subequatorial Pacific begins to play a larger role in shaping diversity than input from the Coral Triangle. This work highlights the enormous dispersal potential of broadcast-spawning corals and identifies the biological and physical drivers that influence coral genetic diversity on a regional scale. © 2014 John Wiley & Sons Ltd.

Thinking and managing outside the box: coalescing connectivity networks to build region-wide resilience in coral reef ecosystems

NASA Astrophysics Data System (ADS)

Steneck, R. S.; Paris, C. B.; Arnold, S. N.; Ablan-Lagman, M. C.; Alcala, A. C.; Butler, M. J.; McCook, L. J.; Russ, G. R.; Sale, P. F.

2009-06-01

As the science of connectivity evolves, so too must the management of coral reefs. It is now clear that the spatial scale of disturbances to coral reef ecosystems is larger and the scale of larval connectivity is smaller than previously thought. This poses a challenge to the current focus of coral reef management, which often centers on the establishment of no-take reserves (NTRs) that in practice are often too small, scattered, or have low stakeholder compliance. Fished species are generally larger and more abundant in protected reserves, where their reproductive potential is often greater, yet documented demographic benefits of these reproductive gains outside reserves are modest at best. Small reproductive populations and limited dispersal of larvae play a role, as does the diminished receptivity to settling larvae of degraded habitats that can limit recruitment by more than 50%. For “demographic connectivity” to contribute to the resilience of coral reefs, it must function beyond the box of no-take reserves. Specifically, it must improve nursery habitats on or near reefs and enhance the reproductive output of ecologically important species throughout coral reef ecosystems. Special protection of ecologically important species (e.g., some herbivores in the Caribbean) and size-regulated fisheries that capitalize on the benefits of NTRs and maintain critical ecological functions are examples of measures that coalesce marine reserve effects and improve the resilience of coral reef ecosystems. Important too is the necessity of local involvement in the management process so that social costs and benefits are properly assessed, compliance increased and success stories accrued.

Pyrosequencing the Midgut Transcriptome of the Banana Weevil Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) Reveals Multiple Protease-Like Transcripts.

PubMed

Valencia, Arnubio; Wang, Haichuan; Soto, Alberto; Aristizabal, Manuel; Arboleda, Jorge W; Eyun, Seong-Il; Noriega, Daniel D; Siegfried, Blair

2016-01-01

The banana weevil Cosmopolites sordidus is an important and serious insect pest in most banana and plantain-growing areas of the world. In spite of the economic importance of this insect pest very little genomic and transcriptomic information exists for this species. In the present study, we characterized the midgut transcriptome of C. sordidus using massive 454-pyrosequencing. We generated over 590,000 sequencing reads that assembled into 30,840 contigs with more than 400 bp, representing a significant expansion of existing sequences available for this insect pest. Among them, 16,427 contigs contained one or more GO terms. In addition, 15,263 contigs were assigned an EC number. In-depth transcriptome analysis identified genes potentially involved in insecticide resistance, peritrophic membrane biosynthesis, immunity-related function and defense against pathogens, and Bacillus thuringiensis toxins binding proteins as well as multiple enzymes involved with protein digestion. This transcriptome will provide a valuable resource for understanding larval physiology and for identifying novel target sites and management approaches for this important insect pest.

Pyrosequencing the Midgut Transcriptome of the Banana Weevil Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) Reveals Multiple Protease-Like Transcripts

PubMed Central

Valencia, Arnubio; Wang, Haichuan; Soto, Alberto; Aristizabal, Manuel; Arboleda, Jorge W.; Eyun, Seong-il; Noriega, Daniel D.; Siegfried, Blair

2016-01-01

The banana weevil Cosmopolites sordidus is an important and serious insect pest in most banana and plantain-growing areas of the world. In spite of the economic importance of this insect pest very little genomic and transcriptomic information exists for this species. In the present study, we characterized the midgut transcriptome of C. sordidus using massive 454-pyrosequencing. We generated over 590,000 sequencing reads that assembled into 30,840 contigs with more than 400 bp, representing a significant expansion of existing sequences available for this insect pest. Among them, 16,427 contigs contained one or more GO terms. In addition, 15,263 contigs were assigned an EC number. In-depth transcriptome analysis identified genes potentially involved in insecticide resistance, peritrophic membrane biosynthesis, immunity-related function and defense against pathogens, and Bacillus thuringiensis toxins binding proteins as well as multiple enzymes involved with protein digestion. This transcriptome will provide a valuable resource for understanding larval physiology and for identifying novel target sites and management approaches for this important insect pest. PMID:26949943

Transcriptome Profiles of the Protoscoleces of Echinococcus granulosus Reveal that Excretory-Secretory Products Are Essential to Metabolic Adaptation

PubMed Central

Pan, Wei; Shen, Yujuan; Han, Xiuming; Wang, Ying; Liu, Hua; Jiang, Yanyan; Zhang, Yumei; Wang, Yanjuan; Xu, Yuxin; Cao, Jianping

2014-01-01

Background Cystic hydatid disease (CHD) is caused by the larval stages of the cestode and affects humans and domestic animals worldwide. Protoscoleces (PSCs) are one component of the larval stages that can interact with both definitive and intermediate hosts. Previous genomic and transcriptomic data have provided an overall snapshot of the genomics of the growth and development of this parasite. However, our understanding of how PSCs subvert the immune response of hosts and maintains metabolic adaptation remains unclear. In this study, we used Roche 454 sequencing technology and in silico secretome analysis to explore the transcriptome profiles of the PSCs from E. granulosus and elucidate the potential functions of the excretory-secretory proteins (ESPs) released by the parasite. Methodology/Principal Findings A large number of nonredundant sequences as unigenes were generated (26,514), of which 22,910 (86.4%) were mapped to the newly published E. granulosus genome and 17,705 (66.8%) were distributed within the coding sequence (CDS) regions. Of the 2,280 ESPs predicted from the transcriptome, 138 ESPs were inferred to be involved in the metabolism of carbohydrates, while 124 ESPs were inferred to be involved in the metabolism of protein. Eleven ESPs were identified as intracellular enzymes that regulate glycolysis/gluconeogenesis (GL/GN) pathways, while a further 44 antigenic proteins, 25 molecular chaperones and four proteases were highly represented. Many proteins were also found to be significantly enriched in development-related signaling pathways, such as the TGF-β receptor pathways and insulin pathways. Conclusions/Significance This study provides valuable information on the metabolic adaptation of parasites to their hosts that can be used to aid the development of novel intervention targets for hydatid treatment and control. PMID:25500817

Venturing in coral larval chimerism: a compact functional domain with fostered genotypic diversity

NASA Astrophysics Data System (ADS)

Rinkevich, Baruch; Shaish, Lee; Douek, Jacob; Ben-Shlomo, Rachel

2016-01-01

The globally distributed coral species Pocillopora damicornis is known to release either sexual or asexual derived planula-larvae in various reef locations. Using microsatellite loci as markers, we documented the release of asexually derived chimeric larvae (CL), originating from mosaicked maternal colonies that were also chimeras, at Thai and Philippines reefs. The CL, each presenting different combinations of maternal genotypic constituents, create genetically-complex sets of asexual propagules. This novel mode of inheritance in corals challenges classical postulations of sexual/asexual reproduction traits, as asexual derived CL represent an alliance between genotypes that significantly sways the recruits’ absolute fitness. This type of inherited chimerism, while enhancing intra-entity genetic heterogeneity, is an evolutionary tactic used to increase genetic-heterogeneity, primarily in new areas colonized by a limited number of larvae. Chimerism may also facilitate combat global change impacts by exhibiting adjustable genomic combinations of within-chimera traits that could withstand alterable environmental pressures, helping Pocillopora become a successful cosmopolitan species.

Faunal breaks and species composition of Indo-Pacific corals: the role of plate tectonics, environment and habitat distribution.

PubMed

Keith, S A; Baird, A H; Hughes, T P; Madin, J S; Connolly, S R

2013-07-22

Species richness gradients are ubiquitous in nature, but the mechanisms that generate and maintain these patterns at macroecological scales remain unresolved. We use a new approach that focuses on overlapping geographical ranges of species to reveal that Indo-Pacific corals are assembled within 11 distinct faunal provinces. Province limits are characterized by co-occurrence of multiple species range boundaries. Unexpectedly, these faunal breaks are poorly predicted by contemporary environmental conditions and the present-day distribution of habitat. Instead, faunal breaks show striking concordance with geological features (tectonic plates and mantle plume tracks). The depth range over which a species occurs, its larval development rate and genus age are important determinants of the likelihood that species will straddle faunal breaks. Our findings indicate that historical processes, habitat heterogeneity and species colonization ability account for more of the present-day biogeographical patterns of corals than explanations based on the contemporary distribution of reefs or environmental conditions.

Faunal breaks and species composition of Indo-Pacific corals: the role of plate tectonics, environment and habitat distribution

PubMed Central

Keith, S. A.; Baird, A. H.; Hughes, T. P.; Madin, J. S.; Connolly, S. R.

2013-01-01

Species richness gradients are ubiquitous in nature, but the mechanisms that generate and maintain these patterns at macroecological scales remain unresolved. We use a new approach that focuses on overlapping geographical ranges of species to reveal that Indo-Pacific corals are assembled within 11 distinct faunal provinces. Province limits are characterized by co-occurrence of multiple species range boundaries. Unexpectedly, these faunal breaks are poorly predicted by contemporary environmental conditions and the present-day distribution of habitat. Instead, faunal breaks show striking concordance with geological features (tectonic plates and mantle plume tracks). The depth range over which a species occurs, its larval development rate and genus age are important determinants of the likelihood that species will straddle faunal breaks. Our findings indicate that historical processes, habitat heterogeneity and species colonization ability account for more of the present-day biogeographical patterns of corals than explanations based on the contemporary distribution of reefs or environmental conditions. PMID:23698011

Reef-scale failure of coral settlement following typhoon disturbance and macroalgal bloom in Palau, Western Pacific

NASA Astrophysics Data System (ADS)

Doropoulos, Christopher; Roff, George; Zupan, Mirta; Nestor, Victor; Isechal, Adelle L.; Mumby, Peter J.

2014-09-01

Factors affecting coral recruitment are critical in influencing the scope and rate of reef recovery after disturbance. In December 2012, super-typhoon Bopha caused immense damage to the eastern reefs of Palau, resulting in near complete loss of coral cover. Within weeks following the typhoon, an ephemeral monospecific bloom of the foliose red macroalga Liagora (up to 40 % cover in February 2013) was recorded at impacted reefs with moderate wave exposure. Conversely, impacted and un-impacted reefs in areas of low wave exposure remained Liagora free. To quantify the effect of this ephemeral macroalgal bloom on coral recruitment, we installed settlement tiles during the major spawning period (March-April 2013) at forereefs with and without Liagora. Reefs ( n = 3) with Liagora (13-24 % cover in April) experienced an almost complete failure of settlement, with only two individual corals recorded on settlement tiles ( n = 90). This settlement failure was unexpected, as tiles were situated adjacent to, and not within Liagora canopies. In contrast, settlement was significantly higher on reefs that lacked macroalgae ( n = 3), ranging from an average of 0.5-2.5 and 2.7-18.9 individuals 25 cm-2 per top- and under-sided tile, respectively. Reefs with and without Liagora were in close proximity (≤8 km), and hydrodynamic models predicted that larval supply did not limit coral settlement among sites. While some differences in the community composition on the tiles were observed among sites, settlement substrate availability also did not limit coral settlement. Generalised linear mixed effects models indicated that while no settlement substrate explained more than 10 % of the variability in coral settlement, coral cover positively accounted for 26 %, and the cover of Liagora on reefs negatively accounted for more than 50 % of the observed variation. Combined, our results indicate that the typhoon induced ephemeral macroalgal bloom resulted in a reef-scale failure of coral settlement.

An Overview of Coral Community Development on Offshore Platforms in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Sammarco, P. W.

2016-02-01

Oil platforms in the N. Gulf of Mexico (GOM) number 1,750, providing hard substratum for settlement of marine fauna, including corals, where little existed in shallow water prior to the 1940s. The introduction of hard substratum has facilitated the biogeographic expansion of Caribbean reef corals. We surveyed scleractinian corals, hermatypic and ahermatypic, on 48 platforms around the Flower Garden Banks (FGB) and across the continental shelf, from Corpus Christi, Texas to Mobile, Alabama, USA. We also assessed coral populations on platforms and the FGB for genetic affinities using AFLPs. The western limit for hermatypes was the shelf edge off Corpus Christi. The highest hermatypic densities occurred at the shelf edge, 200 km from shore in the north-central GOM. Mobile was the eastern limit for some hermatypic corals. Ahermatypes (i.e., Tubastraea coccinea, Oculina diffusa, Phyllangia americana) were absent inshore and in the north-central GOM. Species richness of hermatypic corals peaked near the FGB. Genetic analyses revealed high self-recognition and site fidelity on the platforms and the FGB in Madracis decactis, particularly in the eastern GOM. Platform populations exhibited a strong genetic affinity to those on the FGB, indicating that the FGB are the likely larval source for many corals on the platforms. There was little or no genetic affinity of coral populations across the mouth of the Mississippi River, although in T. coccinea (invasive species), cross-recognition between populations was higher between platforms on a given side. The Mississippi is a strong geographic barrier to east-west dispersal. Brooders were found to be more effective at colonizing patchy habitats at this meso-scale than broadcasters (Diploria strigosa and Montastraea cavernosa). Broadcaster recruits were rarely found, indicating less effective dispersal capabilities. Oil/gas platforms have facilitated the development of coral communities across the northern GOM.

Host adaptation and unexpected symbiont partners enable reef-building corals to tolerate extreme temperatures.

PubMed

Howells, Emily J; Abrego, David; Meyer, Eli; Kirk, Nathan L; Burt, John A

2016-08-01

Understanding the potential for coral adaptation to warming seas is complicated by interactions between symbiotic partners that define stress responses and the difficulties of tracking selection in natural populations. To overcome these challenges, we characterized the contribution of both animal host and symbiotic algae to thermal tolerance in corals that have already experienced considerable warming on par with end-of-century projections for most coral reefs. Thermal responses in Platygyra daedalea corals from the hot Persian Gulf where summer temperatures reach 36°C were compared with conspecifics from the milder Sea of Oman. Persian Gulf corals had higher rates of survival at elevated temperatures (33 and 36°C) in both the nonsymbiotic larval stage (32-49% higher) and the symbiotic adult life stage (51% higher). Additionally, Persian Gulf hosts had fixed greater potential to mitigate oxidative stress (31-49% higher) and their Symbiodinium partners had better retention of photosynthetic performance under elevated temperature (up to 161% higher). Superior thermal tolerance of Persian Gulf vs. Sea of Oman corals was maintained after 6-month acclimatization to a common ambient environment and was underpinned by genetic divergence in both the coral host and symbiotic algae. In P. daedalea host samples, genomewide SNP variation clustered into two discrete groups corresponding with Persian Gulf and Sea of Oman sites. Symbiodinium within host tissues predominantly belonged to ITS2 rDNA type C3 in the Persian Gulf and type D1a in the Sea of Oman contradicting patterns of Symbiodinium thermal tolerance from other regions. Our findings provide evidence that genetic adaptation of both host and Symbiodinium has enabled corals to cope with extreme temperatures in the Persian Gulf. Thus, the persistence of coral populations under continued warming will likely be determined by evolutionary rates in both, rather than single, symbiotic partners. © 2016 John Wiley & Sons Ltd.

Larval fish dispersal in a coral-reef seascape.

PubMed

Almany, Glenn R; Planes, Serge; Thorrold, Simon R; Berumen, Michael L; Bode, Michael; Saenz-Agudelo, Pablo; Bonin, Mary C; Frisch, Ashley J; Harrison, Hugo B; Messmer, Vanessa; Nanninga, Gerrit B; Priest, Mark A; Srinivasan, Maya; Sinclair-Taylor, Tane; Williamson, David H; Jones, Geoffrey P

2017-05-08

Larval dispersal is a critical yet enigmatic process in the persistence and productivity of marine metapopulations. Empirical data on larval dispersal remain scarce, hindering the use of spatial management tools in efforts to sustain ocean biodiversity and fisheries. Here we document dispersal among subpopulations of clownfish (Amphiprion percula) and butterflyfish (Chaetodon vagabundus) from eight sites across a large seascape (10,000 km 2 ) in Papua New Guinea across 2 years. Dispersal of clownfish was consistent between years, with mean observed dispersal distances of 15 km and 10 km in 2009 and 2011, respectively. A Laplacian statistical distribution (the dispersal kernel) predicted a mean dispersal distance of 13-19 km, with 90% of settlement occurring within 31-43 km. Mean dispersal distances were considerably greater (43-64 km) for butterflyfish, with kernels declining only gradually from spawning locations. We demonstrate that dispersal can be measured on spatial scales sufficient to inform the design of and test the performance of marine reserve networks.

Mangroves enhance the biomass of coral reef fish communities in the Caribbean.

PubMed

Mumby, Peter J; Edwards, Alasdair J; Arias-González, J Ernesto; Lindeman, Kenyon C; Blackwell, Paul G; Gall, Angela; Gorczynska, Malgosia I; Harborne, Alastair R; Pescod, Claire L; Renken, Henk; Wabnitz, Colette C C; Llewellyn, Ghislane

2004-02-05

Mangrove forests are one of the world's most threatened tropical ecosystems with global loss exceeding 35% (ref. 1). Juvenile coral reef fish often inhabit mangroves, but the importance of these nurseries to reef fish population dynamics has not been quantified. Indeed, mangroves might be expected to have negligible influence on reef fish communities: juvenile fish can inhabit alternative habitats and fish populations may be regulated by other limiting factors such as larval supply or fishing. Here we show that mangroves are unexpectedly important, serving as an intermediate nursery habitat that may increase the survivorship of young fish. Mangroves in the Caribbean strongly influence the community structure of fish on neighbouring coral reefs. In addition, the biomass of several commercially important species is more than doubled when adult habitat is connected to mangroves. The largest herbivorous fish in the Atlantic, Scarus guacamaia, has a functional dependency on mangroves and has suffered local extinction after mangrove removal. Current rates of mangrove deforestation are likely to have severe deleterious consequences for the ecosystem function, fisheries productivity and resilience of reefs. Conservation efforts should protect connected corridors of mangroves, seagrass beds and coral reefs.

Mangroves enhance the biomass of coral reef fish communities in the Caribbean

NASA Astrophysics Data System (ADS)

Mumby, Peter J.; Edwards, Alasdair J.; Ernesto Arias-González, J.; Lindeman, Kenyon C.; Blackwell, Paul G.; Gall, Angela; Gorczynska, Malgosia I.; Harborne, Alastair R.; Pescod, Claire L.; Renken, Henk; C. C. Wabnitz, Colette; Llewellyn, Ghislane

2004-02-01

Mangrove forests are one of the world's most threatened tropical ecosystems with global loss exceeding 35% (ref. 1). Juvenile coral reef fish often inhabit mangroves, but the importance of these nurseries to reef fish population dynamics has not been quantified. Indeed, mangroves might be expected to have negligible influence on reef fish communities: juvenile fish can inhabit alternative habitats and fish populations may be regulated by other limiting factors such as larval supply or fishing. Here we show that mangroves are unexpectedly important, serving as an intermediate nursery habitat that may increase the survivorship of young fish. Mangroves in the Caribbean strongly influence the community structure of fish on neighbouring coral reefs. In addition, the biomass of several commercially important species is more than doubled when adult habitat is connected to mangroves. The largest herbivorous fish in the Atlantic, Scarus guacamaia, has a functional dependency on mangroves and has suffered local extinction after mangrove removal. Current rates of mangrove deforestation are likely to have severe deleterious consequences for the ecosystem function, fisheries productivity and resilience of reefs. Conservation efforts should protect connected corridors of mangroves, seagrass beds and coral reefs.

Selective predation for low body condition at the larval-juvenile transition of a coral reef fish.

PubMed

Hoey, Andrew S; McCormick, Mark I

2004-03-01

Mortality is known to be high during the transition from larval to juvenile life stages in organisms that have complex life histories. We are only just beginning to understand the processes that influence which individuals survive this period of high mortality, and which traits may be beneficial. Here we document a field experiment that examines the selectivity of predation immediately following settlement to the juvenile population in a common tropical fish, Pomacentrus amboinensis (Pomacentridae). Newly metamorphosed fish were tagged and randomly placed onto replicated patches of natural habitat cleared of resident fishes. After exposure to transient predators for 3 days, fish were recollected and the attributes of survivors from patch reefs that sustained high mortality were compared to individuals from patch reefs that experienced low mortality. Seven characteristics of individuals, which were indicative of previous and present body condition, were compared between groups. Predation was found to be selective for fish that grew slowly in the latter third of their larval phase, were low in total lipids, and had a high standardized weight (Fulton's K). Traits developed in the larval phase can strongly influence the survival of individuals over this critical transition period for organisms with complex life cycles.

Gene Expression Variation Resolves Species and Individual Strains among Coral-Associated Dinoflagellates within the Genus Symbiodinium.

PubMed

Parkinson, John E; Baumgarten, Sebastian; Michell, Craig T; Baums, Iliana B; LaJeunesse, Todd C; Voolstra, Christian R

2016-02-11

Reef-building corals depend on symbiotic mutualisms with photosynthetic dinoflagellates in the genus Symbiodinium. This large microalgal group comprises many highly divergent lineages ("Clades A-I") and hundreds of undescribed species. Given their ecological importance, efforts have turned to genomic approaches to characterize the functional ecology of Symbiodinium. To date, investigators have only compared gene expression between representatives from separate clades-the equivalent of contrasting genera or families in other dinoflagellate groups-making it impossible to distinguish between clade-level and species-level functional differences. Here, we examined the transcriptomes of four species within one Symbiodinium clade (Clade B) at ∼20,000 orthologous genes, as well as multiple isoclonal cell lines within species (i.e., cultured strains). These species span two major adaptive radiations within Clade B, each encompassing both host-specialized and ecologically cryptic taxa. Species-specific expression differences were consistently enriched for photosynthesis-related genes, likely reflecting selection pressures driving niche diversification. Transcriptional variation among strains involved fatty acid metabolism and biosynthesis pathways. Such differences among individuals are potentially a major source of physiological variation, contributing to the functional diversity of coral holobionts composed of unique host-symbiont genotype pairings. Our findings expand the genomic resources available for this important symbiont group and emphasize the power of comparative transcriptomics as a method for studying speciation processes and interindividual variation in nonmodel organisms. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Growth history and intrinsic factors influence risk assessment at a critical life transition for a fish

NASA Astrophysics Data System (ADS)

Lönnstedt, O. M.; McCormick, M. I.

2011-09-01

Making the appropriate decision in the face of predation risk dictates the fate of prey, and predation risk is highest at life history boundaries such as settlement. At the end of the larval phase, most coral reef fishes enter patches of reef containing novel predators. Since vision is often obscured in the complex surroundings, chemical information released from damaged conspecific is used to forewarn prey of an active predator. However, larvae enter the reef environment with their own feeding and growth histories, which will influence their motivation to feed and take risks. The present study explored the link between recent growth, feeding history, current performance and behavioural risk taking in newly settling stages of a coral reef damselfish ( Pomacentrus amboinensis). Older and larger juveniles in good body condition had a stronger response to chemical alarm cues of injured conspecifics; these fish spent a longer time in shelter and displayed a more dramatic decrease in foraging behaviour than fish in lower body condition. Feeding experiments supported these findings and emphasized the importance of body condition in affecting risk assessment. Evidently, larval growth history and body condition influences the likelihood of taking risks under the threat of predation immediately after settlement, thereby affecting the probability of survival in P. amboinensis.

Early transcriptional changes in the reef-building coral Acropora aspera in response to thermal and nutrient stress.

PubMed

Rosic, Nedeljka; Kaniewska, Paulina; Chan, Chon-Kit Kenneth; Ling, Edmund Yew Siang; Edwards, David; Dove, Sophie; Hoegh-Guldberg, Ove

2014-12-02

Changes to the environment as a result of human activities can result in a range of impacts on reef building corals that include coral bleaching (reduced concentrations of algal symbionts), decreased coral growth and calcification, and increased incidence of diseases and mortality. Understanding how elevated temperatures and nutrient concentration affect early transcriptional changes in corals and their algal endosymbionts is critically important for evaluating the responses of coral reefs to global changes happening in the environment. Here, we investigated the expression of genes in colonies of the reef-building coral Acropora aspera exposed to short-term sub-lethal levels of thermal (+6°C) and nutrient stress (ammonium-enrichment: 20 μM). The RNA-Seq data provided hundreds of differentially expressed genes (DEGs) corresponding to various stress regimes, with 115 up- and 78 down-regulated genes common to all stress regimes. A list of DEGs included up-regulated coral genes like cytochrome c oxidase and NADH-ubiquinone oxidoreductase and up-regulated photosynthetic genes of algal origin, whereas coral GFP-like fluorescent chromoprotein and sodium/potassium-transporting ATPase showed reduced transcript levels. Taxonomic analyses of the coral holobiont disclosed the dominant presence of transcripts from coral (~70%) and Symbiodinium (~10-12%), as well as ~15-20% of unknown sequences which lacked sequence identity to known genes. Gene ontology analyses revealed enriched pathways, which led to changes in the dynamics of protein networks affecting growth, cellular processes, and energy requirement. In corals with preserved symbiont physiological performance (based on Fv/Fm, photo-pigment and symbiont density), transcriptomic changes and DEGs provided important insight into early stages of the stress response in the coral holobiont. Although there were no signs of coral bleaching after exposure to short-term thermal and nutrient stress conditions, we managed to detect oxidative stress and apoptotic changes on a molecular level and provide a list of prospective stress biomarkers for both partners in symbiosis. Consequently, our findings are important for understanding and anticipating impacts of anthropogenic global climate change on coral reefs.

Germline DNA methylation in reef corals: patterns and potential roles in response to environmental change.

PubMed

Dimond, James L; Roberts, Steven B

2016-04-01

DNA methylation is an epigenetic mark that plays an inadequately understood role in gene regulation, particularly in nonmodel species. Because it can be influenced by the environment, DNA methylation may contribute to the ability of organisms to acclimatize and adapt to environmental change. We evaluated the distribution of gene body methylation in reef-building corals, a group of organisms facing significant environmental threats. Gene body methylation in six species of corals was inferred from in silico transcriptome analysis of CpG O/E, an estimate of germline DNA methylation that is highly correlated with patterns of methylation enrichment. Consistent with what has been documented in most other invertebrates, all corals exhibited bimodal distributions of germline methylation suggestive of distinct fractions of genes with high and low levels of methylation. The hypermethylated fractions were enriched with genes with housekeeping functions, while genes with inducible functions were highly represented in the hypomethylated fractions. High transcript abundance was associated with intermediate levels of methylation. In three of the coral species, we found that genes differentially expressed in response to thermal stress and ocean acidification exhibited significantly lower levels of methylation. These results support a link between gene body hypomethylation and transcriptional plasticity that may point to a role of DNA methylation in the response of corals to environmental change. © 2015 John Wiley & Sons Ltd.

Influence of Development and Dietary Phospholipid Content and Composition on Intestinal Transcriptome of Atlantic Salmon (Salmo salar)

PubMed Central

De Santis, Christian; Taylor, John F.; Martinez-Rubio, Laura; Boltana, Sebastian; Tocher, Douglas R.

2015-01-01

The inclusion of intact phospholipids in the diet is essential during larval development and can improve culture performance of many fish species. The effects of supplementation of dietary phospholipid from marine (krill) or plant (soy lecithin) sources were investigated in Atlantic salmon, Salmo salar. First feeding fry were fed diets containing either krill oil or soybean lecithin supplying phospholipid at 2.6%, 3.2%, 3.6% and 4.2% of diet. Fish were sampled at ~ 2.5 g (~1,990°day post fertilization, dpf) and ~10 g (2,850°dpf). By comparison of the intestinal transcriptome in specifically chosen contrasts, it was determined that by 2,850°dpf fish possessed a profile that resembled that of mature and differentiated intestinal cell types with a number of changes specific to glycerophospholipid metabolism. It was previously shown that intact phospholipids and particularly phosphatidylcholine are essential during larval development and that this requirement is associated with the inability of enterocytes in young fry to endogenously synthesize sufficient phospholipid for the efficient export of dietary lipid. In the immature phase (~1,990°dpf), the dietary phospholipid content as well as its class composition impacted on several biochemical and morphological parameters including growth, but these differences were not associated with differences in intestinal transcriptomes. The results of this study have made an important contribution to our understanding of the mechanisms associated with lipid transport and phospholipid biosynthesis in early life stages of fish. PMID:26488165

Gene expression patterns during the larval development of European sea bass (dicentrarchus labrax) by microarray analysis.

PubMed

Darias, M J; Zambonino-Infante, J L; Hugot, K; Cahu, C L; Mazurais, D

2008-01-01

During the larval period, marine teleosts undergo very fast growth and dramatic changes in morphology, metabolism, and behavior to accomplish their metamorphosis into juvenile fish. Regulation of gene expression is widely thought to be a key mechanism underlying the management of the biological processes required for harmonious development over this phase of life. To provide an overall analysis of gene expression in the whole body during sea bass larval development, we monitored the expression of 6,626 distinct genes at 10 different points in time between 7 and 43 days post-hatching (dph) by using heterologous hybridization of a rainbow trout cDNA microarray. The differentially expressed genes (n = 485) could be grouped into two categories: genes that were generally up-expressed early, between 7 and 23 dph, and genes up-expressed between 25 and 43 dph. Interestingly, among the genes regulated during the larval period, those related to organogenesis, energy pathways, biosynthesis, and digestion were over-represented compared with total set of analyzed genes. We discuss the quantitative regulation of whole-body contents of these specific transcripts with regard to the ontogenesis and maturation of essential functions that take place over larval development. Our study is the first utilization of a transcriptomic approach in sea bass and reveals dynamic changes in gene expression patterns in relation to marine finfish larval development.

The venom-gland transcriptome of the eastern coral snake (Micrurus fulvius) reveals high venom complexity in the intragenomic evolution of venoms

PubMed Central

2013-01-01

Background Snake venom is shaped by the ecology and evolution of venomous species, and signals of positive selection in toxins have been consistently documented, reflecting the role of venoms as an ecologically critical phenotype. New World coral snakes (Elapidae) are represented by three genera and over 120 species and subspecies that are capable of causing significant human morbidity and mortality, yet coral-snake venom composition is poorly understood in comparison to that of Old World elapids. High-throughput sequencing is capable of identifying thousands of loci, while providing characterizations of expression patterns and the molecular evolutionary forces acting within the venom gland. Results We describe the de novo assembly and analysis of the venom-gland transcriptome of the eastern coral snake (Micrurus fulvius). We identified 1,950 nontoxin transcripts and 116 toxin transcripts. These transcripts accounted for 57.1% of the total reads, with toxins accounting for 45.8% of the total reads. Phospholipases A2 and three-finger toxins dominated expression, accounting for 86.0% of the toxin reads. A total of 15 toxin families were identified, revealing venom complexity previously unknown from New World coral snakes. Toxins exhibited high levels of heterozygosity relative to nontoxins, and overdominance may favor gene duplication leading to the fixation of advantageous alleles. Phospholipase A2 expression was uniformly distributed throughout the class while three-finger toxin expression was dominated by a handful of transcripts, and phylogenetic analyses indicate that toxin divergence may have occurred following speciation. Positive selection was detected in three of the four most diverse toxin classes, suggesting that venom diversification is driven by recurrent directional selection. Conclusions We describe the most complete characterization of an elapid venom gland to date. Toxin gene duplication may be driven by heterozygote advantage, as the frequency of polymorphic toxin loci was significantly higher than that of nontoxins. Diversification among toxins appeared to follow speciation reflecting species-specific adaptation, and this divergence may be directly related to dietary shifts and is suggestive of a coevolutionary arms race. PMID:23915248

The venom-gland transcriptome of the eastern coral snake (Micrurus fulvius) reveals high venom complexity in the intragenomic evolution of venoms.

PubMed

Margres, Mark J; Aronow, Karalyn; Loyacano, Jacob; Rokyta, Darin R

2013-08-02

Snake venom is shaped by the ecology and evolution of venomous species, and signals of positive selection in toxins have been consistently documented, reflecting the role of venoms as an ecologically critical phenotype. New World coral snakes (Elapidae) are represented by three genera and over 120 species and subspecies that are capable of causing significant human morbidity and mortality, yet coral-snake venom composition is poorly understood in comparison to that of Old World elapids. High-throughput sequencing is capable of identifying thousands of loci, while providing characterizations of expression patterns and the molecular evolutionary forces acting within the venom gland. We describe the de novo assembly and analysis of the venom-gland transcriptome of the eastern coral snake (Micrurus fulvius). We identified 1,950 nontoxin transcripts and 116 toxin transcripts. These transcripts accounted for 57.1% of the total reads, with toxins accounting for 45.8% of the total reads. Phospholipases A(2) and three-finger toxins dominated expression, accounting for 86.0% of the toxin reads. A total of 15 toxin families were identified, revealing venom complexity previously unknown from New World coral snakes. Toxins exhibited high levels of heterozygosity relative to nontoxins, and overdominance may favor gene duplication leading to the fixation of advantageous alleles. Phospholipase A(2) expression was uniformly distributed throughout the class while three-finger toxin expression was dominated by a handful of transcripts, and phylogenetic analyses indicate that toxin divergence may have occurred following speciation. Positive selection was detected in three of the four most diverse toxin classes, suggesting that venom diversification is driven by recurrent directional selection. We describe the most complete characterization of an elapid venom gland to date. Toxin gene duplication may be driven by heterozygote advantage, as the frequency of polymorphic toxin loci was significantly higher than that of nontoxins. Diversification among toxins appeared to follow speciation reflecting species-specific adaptation, and this divergence may be directly related to dietary shifts and is suggestive of a coevolutionary arms race.

Uncovering the immune responses of Apis mellifera ligustica larval gut to Ascosphaera apis infection utilizing transcriptome sequencing.

PubMed

Chen, Dafu; Guo, Rui; Xu, Xijian; Xiong, Cuiling; Liang, Qin; Zheng, Yanzhen; Luo, Qun; Zhang, Zhaonan; Huang, Zhijian; Kumar, Dhiraj; Xi, Weijun; Zou, Xuan; Liu, Min

2017-07-20

Honeybees are susceptible to a variety of diseases, including chalkbrood, which is capable of causing huge losses of both the number of bees and colony productivity. This research is designed to characterize the transcriptome profiles of Ascosphaera apis-treated and un-treated larval guts of Apis mellifera ligustica in an attempt to unravel the molecular mechanism underlying the immune responses of western honeybee larval guts to mycosis. In this study, 24, 296 and 2157 genes were observed to be differentially expressed in A. apis-treated Apis mellifera (4-, 5- and 6-day-old) compared with un-treated larval guts. Moreover, the expression patterns of differentially expressed genes (DEGs) were examined via trend analysis, and subsequently, gene ontology analysis and KEGG pathway enrichment analysis were conducted for DEGs involved in up- and down-regulated profiles. Immunity-related pathways were selected for further analysis, and our results demonstrated that a total of 13 and 50 DEGs were annotated in the humoral immune-related and cellular immune-related pathways, respectively. Additionally, we observed that many DEGs up-regulated in treated guts were part of cellular immune pathways, such as the lysosome, ubiquitin mediated proteolysis, and insect hormone biosynthesis pathways and were induced by A. apis invasion. However, more down-regulated DEGs were restrained. Surprisingly, a majority of DEGs within the Toll-like receptor signaling pathway, and the MAPK signaling pathway were up-regulated in treated guts, while all but two genes involved in the NF-κB signaling pathway were down-regulated, which suggested that most genes involved in humoral immune-related pathways were activated in response to the invasive fungal pathogen. This study's findings provide valuable information regarding the investigation of the molecular mechanism of immunity defenses of A. m. ligustica larval guts to infection with A. apis. Furthermore, these studies lay the groundwork for future researches on key genes controlling the susceptibility of A. m. ligustica larvae to chalkbrood. Copyright © 2017 Elsevier B.V. All rights reserved.

Preconditioning in the reef-building coral Pocillopora damicornis and the potential for trans-generational acclimatization in coral larvae under future climate change conditions.

PubMed

Putnam, Hollie M; Gates, Ruth D

2015-08-01

Coral reefs are globally threatened by climate change-related ocean warming and ocean acidification (OA). To date, slow-response mechanisms such as genetic adaptation have been considered the major determinant of coral reef persistence, with little consideration of rapid-response acclimatization mechanisms. These rapid mechanisms such as parental effects that can contribute to trans-generational acclimatization (e.g. epigenetics) have, however, been identified as important contributors to offspring response in other systems. We present the first evidence of parental effects in a cross-generational exposure to temperature and OA in reef-building corals. Here, we exposed adults to high (28.9°C, 805 µatm P(CO2)) or ambient (26.5°C, 417 µatm P(CO2)) temperature and OA treatments during the larval brooding period. Exposure to high treatment negatively affected adult performance, but their larvae exhibited size differences and metabolic acclimation when subsequently re-exposed, unlike larvae from parents exposed to ambient conditions. Understanding the innate capacity corals possess to respond to current and future climatic conditions is essential to reef protection and maintenance. Our results identify that parental effects may have an important role through (1) ameliorating the effects of stress through preconditioning and adaptive plasticity, and/or (2) amplifying the negative parental response through latent effects on future life stages. Whether the consequences of parental effects and the potential for trans-generational acclimatization are beneficial or maladaptive, our work identifies a critical need to expand currently proposed climate change outcomes for corals to further assess rapid response mechanisms that include non-genetic inheritance through parental contributions and classical epigenetic mechanisms. © 2015. Published by The Company of Biologists Ltd.

Ontogenetic changes in responses to settlement cues by Anemonefish

NASA Astrophysics Data System (ADS)

Dixson, D. L.; Munday, P. L.; Pratchett, M.; Jones, G. P.

2011-12-01

Population connectivity for most marine species is dictated by dispersal during the pelagic larval stage. Although reef fish larvae are known to display behavioral adaptations that influence settlement site selection, little is known about the development of behavioral preferences throughout the larval phase. Whether larvae are attracted to the same sensory cues throughout their larval phase, or exhibit distinct ontogenetic shifts in sensory preference is unknown. Here, we demonstrate an ontogenetic shift in olfactory cue preferences for two species of anemonefish, a process that could aid in understanding both patterns of dispersal and settlement. Aquarium-bred naïve Amphiprion percula and A. melanopus larvae were tested for olfactory preference of relevant reef-associated chemical cues throughout the 11-day pelagic larval stage. Age posthatching had a significant effect on the preference for olfactory cues from host anemones and live corals for both species. Preferences of olfactory cues from tropical plants of A. percula, increased by approximately ninefold between hatching and settlement, with A. percula larvae showing a fivefold increase in preference for the olfactory cue produced by the grass species. Larval age had no effect on the olfactory preference for untreated seawater over the swamp-based tree Melaleuca nervosa, which was always avoided compared with blank seawater. These results indicate that reef fish larvae are capable of utilizing olfactory cues early in the larval stage and may be predisposed to disperse away from reefs, with innate olfactory preferences drawing newly hatched larvae into the pelagic environment. Toward the end of the larval phase, larvae become attracted to the olfactory cues of appropriate habitats, which may assist them in identification of and navigation toward suitable settlement sites.

Recruitment constraints in Singapore's fluted giant clam (Tridacna squamosa) population—A dispersal model approach

PubMed Central

Neo, Mei Lin; Erftemeijer, Paul L. A.; van Beek, Jan K. L.; van Maren, Dirk S.; Teo, Serena L-M.; Todd, Peter A.

2013-01-01

Recruitment constraints on Singapore's dwindling fluted giant clam, Tridacna squamosa, population were studied by modelling fertilisation, larval transport, and settlement using real-time hydrodynamic forcing combined with knowledge of spawning characteristics, larval development, behaviour, and settlement cues. Larval transport was simulated using a finite-volume advection-diffusion model coupled to a three-dimensional hydrodynamic model. Three recruitment constraint hypotheses were tested: 1) there is limited connectivity between Singapore's reefs and other reefs in the region, 2) there is limited exchange within Singapore's Southern Islands, and 3) there exist low-density constraints to fertilisation efficacy (component Allee effects). Results showed that connectivity among giant clam populations was primarily determined by residual hydrodynamic flows and spawning time, with greatest chances of successful settlement occurring when spawning and subsequent larval dispersal coincided with the period of lowest residual flow. Simulations suggested poor larval transport from reefs located along the Peninsular Malaysia to Singapore, probably due to strong surface currents between the Andaman Sea and South China Sea combined with a major land barrier disrupting larval movement among reefs. The model, however, predicted offshore coral reefs to the southeast of Singapore (Bintan and Batam) may represent a significant source of larvae. Larval exchange within Singapore's Southern Islands varied substantially depending on the locations of source and sink reefs as well as spawning time; but all simulations resulted in low settler densities (2.1–68.6 settled individuals per 10,000 m2). Poor fertilisation rates predicted by the model indicate that the low density and scattered distribution of the remaining T. squamosa in Singapore are likely to significantly inhibit any natural recovery of local stocks. PMID:23555597

Sex, Scavengers, and Chaperones: Transcriptome Secrets of Divergent Symbiodinium Thermal Tolerances.

PubMed

Levin, Rachel A; Beltran, Victor H; Hill, Ross; Kjelleberg, Staffan; McDougald, Diane; Steinberg, Peter D; van Oppen, Madeleine J H

2016-09-01

Corals rely on photosynthesis by their endosymbiotic dinoflagellates (Symbiodinium spp.) to form the basis of tropical coral reefs. High sea surface temperatures driven by climate change can trigger the loss of Symbiodinium from corals (coral bleaching), leading to declines in coral health. Different putative species (genetically distinct types) as well as conspecific populations of Symbiodinium can confer differing levels of thermal tolerance to their coral host, but the genes that govern dinoflagellate thermal tolerance are unknown. Here we show physiological and transcriptional responses to heat stress by a thermo-sensitive (physiologically susceptible at 32 °C) type C1 Symbiodinium population and a thermo-tolerant (physiologically healthy at 32 °C) type C1 Symbiodinium population. After nine days at 32 °C, neither population exhibited physiological stress, but both displayed up-regulation of meiosis genes by ≥ 4-fold and enrichment of meiosis functional gene groups, which promote adaptation. After 13 days at 32 °C, the thermo-sensitive population suffered a significant decrease in photosynthetic efficiency and increase in reactive oxygen species (ROS) leakage from its cells, whereas the thermo-tolerant population showed no signs of physiological stress. Correspondingly, only the thermo-tolerant population demonstrated up-regulation of a range of ROS scavenging and molecular chaperone genes by ≥ 4-fold and enrichment of ROS scavenging and protein-folding functional gene groups. The physiological and transcriptional responses of the Symbiodinium populations to heat stress directly correlate with the bleaching susceptibilities of corals that harbored these same Symbiodinium populations. Thus, our study provides novel, foundational insights into the molecular basis of dinoflagellate thermal tolerance and coral bleaching. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Sex, Scavengers, and Chaperones: Transcriptome Secrets of Divergent Symbiodinium Thermal Tolerances

PubMed Central

Levin, Rachel A.; Beltran, Victor H.; Hill, Ross; Kjelleberg, Staffan; McDougald, Diane; Steinberg, Peter D.; van Oppen, Madeleine J. H.

2016-01-01

Corals rely on photosynthesis by their endosymbiotic dinoflagellates (Symbiodinium spp.) to form the basis of tropical coral reefs. High sea surface temperatures driven by climate change can trigger the loss of Symbiodinium from corals (coral bleaching), leading to declines in coral health. Different putative species (genetically distinct types) as well as conspecific populations of Symbiodinium can confer differing levels of thermal tolerance to their coral host, but the genes that govern dinoflagellate thermal tolerance are unknown. Here we show physiological and transcriptional responses to heat stress by a thermo-sensitive (physiologically susceptible at 32 °C) type C1 Symbiodinium population and a thermo-tolerant (physiologically healthy at 32 °C) type C1 Symbiodinium population. After nine days at 32 °C, neither population exhibited physiological stress, but both displayed up-regulation of meiosis genes by ≥ 4-fold and enrichment of meiosis functional gene groups, which promote adaptation. After 13 days at 32 °C, the thermo-sensitive population suffered a significant decrease in photosynthetic efficiency and increase in reactive oxygen species (ROS) leakage from its cells, whereas the thermo-tolerant population showed no signs of physiological stress. Correspondingly, only the thermo-tolerant population demonstrated up-regulation of a range of ROS scavenging and molecular chaperone genes by ≥ 4-fold and enrichment of ROS scavenging and protein-folding functional gene groups. The physiological and transcriptional responses of the Symbiodinium populations to heat stress directly correlate with the bleaching susceptibilities of corals that harbored these same Symbiodinium populations. Thus, our study provides novel, foundational insights into the molecular basis of dinoflagellate thermal tolerance and coral bleaching. PMID:27301593

High natural gene expression variation in the reef-building coral Acropora millepora: potential for acclimative and adaptive plasticity.

PubMed

Granados-Cifuentes, Camila; Bellantuono, Anthony J; Ridgway, Tyrone; Hoegh-Guldberg, Ove; Rodriguez-Lanetty, Mauricio

2013-04-08

Ecosystems worldwide are suffering the consequences of anthropogenic impact. The diverse ecosystem of coral reefs, for example, are globally threatened by increases in sea surface temperatures due to global warming. Studies to date have focused on determining genetic diversity, the sequence variability of genes in a species, as a proxy to estimate and predict the potential adaptive response of coral populations to environmental changes linked to climate changes. However, the examination of natural gene expression variation has received less attention. This variation has been implicated as an important factor in evolutionary processes, upon which natural selection can act. We acclimatized coral nubbins from six colonies of the reef-building coral Acropora millepora to a common garden in Heron Island (Great Barrier Reef, GBR) for a period of four weeks to remove any site-specific environmental effects on the physiology of the coral nubbins. By using a cDNA microarray platform, we detected a high level of gene expression variation, with 17% (488) of the unigenes differentially expressed across coral nubbins of the six colonies (jsFDR-corrected, p < 0.01). Among the main categories of biological processes found differentially expressed were transport, translation, response to stimulus, oxidation-reduction processes, and apoptosis. We found that the transcriptional profiles did not correspond to the genotype of the colony characterized using either an intron of the carbonic anhydrase gene or microsatellite loci markers. Our results provide evidence of the high inter-colony variation in A. millepora at the transcriptomic level grown under a common garden and without a correspondence with genotypic identity. This finding brings to our attention the importance of taking into account natural variation between reef corals when assessing experimental gene expression differences. The high transcriptional variation detected in this study is interpreted and discussed within the context of adaptive potential and phenotypic plasticity of reef corals. Whether this variation will allow coral reefs to survive to current challenges remains unknown.

The Skeletal Proteome of the Coral Acropora millepora: The Evolution of Calcification by Co-Option and Domain Shuffling

PubMed Central

Ramos-Silva, Paula; Kaandorp, Jaap; Huisman, Lotte; Marie, Benjamin; Zanella-Cléon, Isabelle; Guichard, Nathalie; Miller, David J.; Marin, Frédéric

2013-01-01

In corals, biocalcification is a major function that may be drastically affected by ocean acidification (OA). Scleractinian corals grow by building up aragonitic exoskeletons that provide support and protection for soft tissues. Although this process has been extensively studied, the molecular basis of biocalcification is poorly understood. Notably lacking is a comprehensive catalog of the skeleton-occluded proteins—the skeletal organic matrix proteins (SOMPs) that are thought to regulate the mineral deposition. Using a combination of proteomics and transcriptomics, we report the first survey of such proteins in the staghorn coral Acropora millepora. The organic matrix (OM) extracted from the coral skeleton was analyzed by mass spectrometry and bioinformatics, enabling the identification of 36 SOMPs. These results provide novel insights into the molecular basis of coral calcification and the macroevolution of metazoan calcifying systems, whereas establishing a platform for studying the impact of OA at molecular level. Besides secreted proteins, extracellular regions of transmembrane proteins are also present, suggesting a close control of aragonite deposition by the calicoblastic epithelium. In addition to the expected SOMPs (Asp/Glu-rich, galaxins), the skeletal repertoire included several proteins containing known extracellular matrix domains. From an evolutionary perspective, the number of coral-specific proteins is low, many SOMPs having counterparts in the noncalcifying cnidarians. Extending the comparison with the skeletal OM proteomes of other metazoans allowed the identification of a pool of functional domains shared between phyla. These data suggest that co-option and domain shuffling may be general mechanisms by which the trait of calcification has evolved. PMID:23765379

Identifying the ichthyoplankton of a coral reef using DNA barcodes.

PubMed

Hubert, Nicolas; Espiau, Benoit; Meyer, Christopher; Planes, Serge

2015-01-01

Marine fishes exhibit spectacular phenotypic changes during their ontogeny, and the identification of their early stages is challenging due to the paucity of diagnostic morphological characters at the species level. Meanwhile, the importance of early life stages in dispersal and connectivity has recently experienced an increasing interest in conservation programmes for coral reef fishes. This study aims at assessing the effectiveness of DNA barcoding for the automated identification of coral reef fish larvae through large-scale ecosystemic sampling. Fish larvae were mainly collected using bongo nets and light traps around Moorea between September 2008 and August 2010 in 10 sites distributed in open waters. Fish larvae ranged from 2 to 100 mm of total length, with the most abundant individuals being <5 mm. Among the 505 individuals DNA barcoded, 373 larvae (i.e. 75%) were identified to the species level. A total of 106 species were detected, among which 11 corresponded to pelagic and bathypelagic species, while 95 corresponded to species observed at the adult stage on neighbouring reefs. This study highlights the benefits and pitfalls of using standardized molecular systems for species identification and illustrates the new possibilities enabled by DNA barcoding for future work on coral reef fish larval ecology. © 2014 John Wiley & Sons Ltd.

Phototoxic effects of PAH and UVA exposure on molecular responses and developmental success in coral larvae.

PubMed

Overmans, Sebastian; Nordborg, Mikaela; Díaz-Rúa, Rubén; Brinkman, Diane L; Negri, Andrew P; Agustí, Susana

2018-05-01

Exposure to polycyclic aromatic carbons (PAHs) poses a growing risk to coral reefs due to increasing shipping and petroleum extraction in tropical waters. Damaging effects of specific PAHs can be further enhanced by the presence of ultraviolet radiation, known as phototoxicity. We tested phototoxic effects of the PAHs anthracene and phenanthrene on larvae of the scleractinian coral Acropora tenuis in the presence and absence of UVA (320-400 nm). Activity of superoxide dismutase (SOD) enzyme was reduced by anthracene while phenanthrene and UVA exposure did not have any effect. Gene expression of MnSod remained constant across all treatments. The genes Catalase, Hsp70 and Hsp90 showed increased expression levels in larvae exposed to anthracene, but not phenanthrene. Gene expression of p53 was upregulated in the presence of UVA, but downregulated when exposed to PAHs. The influence on stress-related biochemical pathways and gene expresson in A. tenuis larvae was considerably greater for anthracene than phenanthrene, and UVA-induced phototoxicity was only evident for anthracene. The combined effects of UVA and PAH exposure on larval survival and metamorphosis paralleled the sub-lethal stress responses, clearly highlighting the interaction of UVA on anthracene toxicity and ultimately the coral's development. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

A picture on the wall: innovative mapping reveals cold-water coral refuge in submarine canyon.

PubMed

Huvenne, Veerle A I; Tyler, Paul A; Masson, Doug G; Fisher, Elizabeth H; Hauton, Chris; Hühnerbach, Veit; Le Bas, Timothy P; Wolff, George A

2011-01-01

Cold-water corals are azooxanthellate species found throughout the ocean at water depths down to 5000 m. They occur in patches, reefs or large mound structures up to 380 m high, and as ecosystem engineers create important habitats for a diverse fauna. However, the majority of these habitats are now within reach of deep-sea bottom trawling. Many have been severely damaged or are under threat, despite recent protection initiatives. Here we present a cold-water coral habitat type that so far has been overlooked--quite literally--and that has received minimal impact from human activities. Vertical and overhanging cliffs in deep-sea canyons, revealed using an innovative approach to marine habitat mapping, are shown to provide the perfect substratum for extensive cold-water coral-based communities. Typical canyon-related processes, including locally enhanced internal tides and focussed downslope organic carbon transport, provide favourable environmental conditions (current regime, food input) to sustain the communities, even outside the optimal depth and density envelopes reported elsewhere in the NE Atlantic. Our findings show that deep-sea canyons can form natural refuges for faunal communities sensitive to anthropogenic disturbance, and have the potential to fulfil the crucial role of larval sources for the recolonisation of damaged sites elsewhere on the margin.

A Picture on the Wall: Innovative Mapping Reveals Cold-Water Coral Refuge in Submarine Canyon

PubMed Central

Huvenne, Veerle A. I.; Tyler, Paul A.; Masson, Doug G.; Fisher, Elizabeth H.; Hauton, Chris; Hühnerbach, Veit; Le Bas, Timothy P.; Wolff, George A.

2011-01-01

Cold-water corals are azooxanthellate species found throughout the ocean at water depths down to 5000 m. They occur in patches, reefs or large mound structures up to 380 m high, and as ecosystem engineers create important habitats for a diverse fauna. However, the majority of these habitats are now within reach of deep-sea bottom trawling. Many have been severely damaged or are under threat, despite recent protection initiatives. Here we present a cold-water coral habitat type that so far has been overlooked – quite literally – and that has received minimal impact from human activities. Vertical and overhanging cliffs in deep-sea canyons, revealed using an innovative approach to marine habitat mapping, are shown to provide the perfect substratum for extensive cold-water coral-based communities. Typical canyon-related processes, including locally enhanced internal tides and focussed downslope organic carbon transport, provide favourable environmental conditions (current regime, food input) to sustain the communities, even outside the optimal depth and density envelopes reported elsewhere in the NE Atlantic. Our findings show that deep-sea canyons can form natural refuges for faunal communities sensitive to anthropogenic disturbance, and have the potential to fulfil the crucial role of larval sources for the recolonisation of damaged sites elsewhere on the margin. PMID:22194903

DNA barcoding as a tool for coral reef conservation

NASA Astrophysics Data System (ADS)

Neigel, J.; Domingo, A.; Stake, J.

2007-09-01

DNA Barcoding (DBC) is a method for taxonomic identification of animals that is based entirely on the 5' portion of the mitochondrial gene, cytochrome oxidase subunit I ( COI-5). It can be especially useful for identification of larval forms or incomplete specimens lacking diagnostic morphological characters. DBC can also facilitate the discovery of species and in defining “molecular taxonomic units” in problematic groups. However, DBC is not a panacea for coral reef taxonomy. In two of the most ecologically important groups on coral reefs, the Anthozoa and Porifera, COI-5 sequences have diverged too little to be diagnostic for all species. Other problems for DBC include paraphyly in mitochondrial gene trees and lack of differentiation between hybrids and their maternal ancestors. DBC also depends on the availability of databases of COI-5 sequences, which are still in early stages of development. A global effort to barcode all fish species has demonstrated the importance of large-scale coordination and is yielding promising results. Whether or not COI-5 by itself is sufficient for species assignments has become a contentious question; it is generally advantageous to use sequences from multiple loci.

Small Marine Protected Areas in Fiji Provide Refuge for Reef Fish Assemblages, Feeding Groups, and Corals

PubMed Central

Pires, Mathias M.; Guimarães, Paulo Roberto; Hoey, Andrew S.; Hay, Mark E.

2017-01-01

The establishment of no-take marine protected areas (MPAs) on coral reefs is a common management strategy for conserving the diversity, abundance, and biomass of reef organisms. Generally, well-managed and enforced MPAs can increase or maintain the diversity and function of the enclosed coral reef, with some of the benefits extending to adjacent non-protected reefs. A fundamental question in coral reef conservation is whether these benefits arise within small MPAs (<1 km2), because larval input of reef organisms is largely decoupled from local adult reproduction. We examined the structure of fish assemblages, composition of fish feeding groups, benthic cover, and key ecosystem processes (grazing, macroalgal browsing, and coral replenishment) in three small (0.5–0.8 km2) no-take MPAs and adjacent areas where fisheries are allowed (non-MPAs) on coral reefs in Fiji. The MPAs exhibited greater species richness, density, and biomass of fishes than non-MPAs. Furthermore, MPAs contained a greater abundance and biomass of grazing herbivores and piscivores as well as a greater abundance of cleaners than fished areas. We also found differences in fish associations when foraging, with feeding groups being generally more diverse and having greater biomass within MPAs than adjacent non-MPAs. Grazing by parrotfishes was 3–6 times greater, and macroalgal browsing was 3–5 times greater in MPAs than in non-MPAs. On average, MPAs had 260–280% as much coral cover and only 5–25% as much macroalgal cover as their paired non-MPA sites. Finally, two of the three MPAs had three-fold more coral recruits than adjacent non-MPAs. The results of this study indicate that small MPAs benefit not only populations of reef fishes, but also enhance ecosystem processes that are critical to reef resilience within the MPAs. PMID:28122006

Application of Habitat Equivalency Analysis to USACE Projects

DTIC Science & Technology

2009-04-01

reef, open - water bay bottoms, and water column habitats. Of the four case studies, Craney Island is the only one where the logic behind the choice of...Act (NEPA) of 1969, the Federal Water Pollution Act (Clean Water Act) of 1972, and the Water Resources Development Act (WRDA) of 1986, as well as...mitigation. These habitats support a diverse assemblage of sponges, algae , and soft and hard corals, provide habitat for larval fish, and are considered

Diel ontogenetic shift in parasitic activity in a gnathiid isopod on Caribbean coral reefs

NASA Astrophysics Data System (ADS)

Sikkel, P. C.; Ziemba, R. E.; Sears, W. T.; Wheeler, J. C.

2009-06-01

Ontogenetic niche shifts are characteristic of organisms with complex life cycles such as many marine invertebrates. Research has focused primarily on changes in habitat or diet. However, ontogenetic changes can also occur in the temporal pattern of foraging. Gnathiid isopods feed on fish blood throughout their larval stages and are the primary food item for cleaning organisms on coral reefs. At sites in Australia and the Caribbean, gnathiid larvae exhibit size-related differences in diel activity. However, it is unclear whether this is due to interspecific or intraspecific variation in behavior. Fish were deployed in cages near sunset on shallow reefs off St. John, U.S. Virgin Islands and allowed to be infected with larval gnathiids. Larvae collected from fish retrieved near midnight developed into adults, with most developing into females. In contrast, approximately 80% of gnathiids collected after first light developed into second or third stage larvae, and nearly all of the remaining, large, individuals developed into males. Comparison of ITS2 gene regions from individuals collected in emergence traps from the same reefs during the day versus during the night revealed no differences in this highly variable region. Thus, gnathiid larvae at this locality shift their time of activity as they develop, and larvae developing into males remain active over a longer time period than those developing into females.

Do human activities influence survival and orientation abilities of larval fishes in the ocean?

PubMed

Siebeck, Ulrike E; O'Connor, Jack; Braun, Christoph; Leis, Jeffrey M

2015-01-01

The larval stages of most marine fishes spend days to weeks in the pelagic environment, where they must find food and avoid predators in order to survive. Some fish only spend part of their life history in the pelagic environment before returning to their adult habitat, for example, a coral reef. The sensory systems of larval fish develop rapidly during the first few days of their lives, and here we concentrate on the various sensory cues the fish have available to them for survival in the pelagic environment. We focus on the larvae of reef fishes because most is known about them. We also review the major threats caused by human activities that have been identified to have worldwide impact and evaluate how these threats may impact larval-fish survival and orientation abilities. Many human activities negatively affect larval-fish sensory systems or the cues the fish need to detect. Ultimately, this could lead to decreased numbers of larvae surviving to settlement, and, therefore, to decreased abundance of adult fishes. Although we focus on species wherein the larvae and adults occupy different habitats (pelagic and demersal, respectively), it is important to acknowledge that the potential anthropogenic effects we identify may also apply to larvae of species like tuna and herring, where both larvae and adults are pelagic. © 2014 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

Characterization of receptor of activated C kinase 1 (RACK1) and functional analysis during larval metamorphosis of the oyster Crassostrea angulata.

PubMed

Yang, Bingye; Pu, Fei; Qin, Ji; You, Weiwei; Ke, Caihuan

2014-03-10

During a large-scale screen of the larval transcriptome library of the Portuguese oyster, Crassostrea angulata, the oyster gene RACK, which encodes a receptor of activated protein kinase C protein was isolated and characterized. The cDNA is 1,148 bp long and has a predicted open reading frame encoding 317 aa. The predicted protein shows high sequence identity to many RACK proteins of different organisms including molluscs, fish, amphibians and mammals, suggesting that it is conserved during evolution. The structural analysis of the Ca-RACK1 genomic sequence implies that the Ca-RACK1 gene has seven exons and six introns, extending approximately 6.5 kb in length. It is expressed ubiquitously in many oyster tissues as detected by RT-PCR analysis. The Ca-RACK1 mRNA expression pattern was markedly increased at larval metamorphosis; and was further increased along with Ca-RACK1 protein synthesis during epinephrine-induced metamorphosis. These results indicate that the Ca-RACK1 plays an important role in tissue differentiation and/or in cell growth during larval metamorphosis in the oyster, C. angulata. Copyright © 2013 Elsevier B.V. All rights reserved.

Immunity to community: what can immune pathways tell us about disease patterns in corals?

NASA Astrophysics Data System (ADS)

Mydlarz, L. D.; Fuess, L.; Pinzon, J. C.; Weil, E.

2016-02-01

Predicting species composition and abundances is one of the most fundamental questions in ecology. This question is even more pressing in marine ecology and coral reefs since communities are changing at a rapid pace due to climate-related changes. Increases in disease prevalence and severity are just some of the consequences of these environmental changes. Particularly in coral reef ecosystems, diseases are increasing and driving region-wide population collapses. It has become clear, however, that not all reefs or coral species are affected by disease equally. In fact, the Caribbean is a concentrated area for diseases. The patterns in which disease manifests itself on an individual reef are also proving interesting, as not all coral species are affected by disease equally. Some species are host to different diseases, but seem to successfully fight them reducing mortality. Other species are disproportionately infected on any given reef and experience high mortality due to disease. We are interested in the role immunity can play in directing these patterns and are evaluating coral immunity using several novel approaches. We exposed 4 species of corals with different disease susceptibilities to immune stimulators and quantified of coral immunity using a combination of full transcriptome sequencing and protein activity assays for gene to phenotype analysis. We also mapped gene expression changes onto immune pathways (i.e. melanin-cascade, antimicrobial peptide synthesis, complement cascade, lectin-opsonization) to evaluate expression of immune pathways between species. In our preliminary data we found many immune genes in the disease susceptible Orbicella faveolata underwent changes in gene expression opposite of the predictions and may disply `dysfunctional' patterns of expression. We will present expression data for 4 species of coral and assess how these transcriptional and protein immune responses are related to disease susceptibility in nature, thus scaling up from immune pathway to natural patterns of disease.

Corallimorpharians are not “naked corals”: insights into relationships between Scleractinia and Corallimorpharia from phylogenomic analyses

PubMed Central

Lin, Mei Fang; Chou, Wen Hwa; Kitahara, Marcelo V.; Chen, Chao Lun Allen

2016-01-01

Calcification is one of the most distinctive traits of scleractinian corals. Their hard skeletons form the substratum of reef ecosystems and confer on corals their remarkable diversity of shapes. Corallimorpharians are non-calcifying, close relatives of scleractinian corals, and the evolutionary relationship between these two groups is key to understanding the evolution of calcification in the coral lineage. One pivotal question is whether scleractinians are a monophyletic group, paraphyly being an alternative possibility if corallimorpharians are corals that have lost their ability to calcify, as is implied by the “naked-coral” hypothesis. Despite major efforts, relationships between scleractinians and corallimorpharians remain equivocal and controversial. Although the complete mitochondrial genomes of a range of scleractinians and corallimorpharians have been obtained, heterogeneity in composition and evolutionary rates means that mitochondrial sequences are insufficient to understand the relationship between these two groups. To overcome these limitations, transcriptome data were generated for three representative corallimorpharians. These were used in combination with sequences available for a representative range of scleractinians to identify 291 orthologous single copy protein-coding nuclear markers. Unlike the mitochondrial sequences, these nuclear markers do not display any distinct compositional bias in their nucleotide or amino-acid sequences. A range of phylogenomic approaches congruently reveal a topology consistent with scleractinian monophyly and corallimorpharians as the sister clade of scleractinians. PMID:27761308

Monitoring Land Based Sources of Pollution over Coral Reefs using VIIRS Ocean Color Products

NASA Astrophysics Data System (ADS)

Geiger, E.; Strong, A. E.; Eakin, C. M.; Wang, M.; Hernandez, W. J.; Cardona Maldonado, M. A.; De La Cour, J. L.; Liu, G.; Tirak, K.; Heron, S. F.; Skirving, W. J.; Armstrong, R.; Warner, R. A.

2016-02-01

NOAA's Coral Reef Watch (CRW) program and the NESDIS Ocean Color Team are developing new products to monitor land based sources of pollution (LBSP) over coral reef ecosystems using the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the S-NPP satellite. LBSP are a major threat to corals that can cause disease and mortality, disrupt critical ecological reef functions, and impede growth, reproduction, and larval settlement, among other impacts. From VIIRS, near-real-time satellite products of Chlorophyll-a, Kd(490), and sea surface temperature are being developed for three U.S. Coral Reef Task Force priority watershed sites - Ka'anapali (West Maui, Hawai'i), Faga'alu (American Samoa), and Guánica Bay (Puerto Rico). Background climatological levels of these parameters are being developed to construct anomaly products. Time-series data are being generated to monitor changes in water quality in near-real-time and provide information on historical variations, especially following significant rain events. A pilot calibration/validation field study of the VIIRS-based ocean color products is underway in Puerto Rico; we plan to expand this validation effort to the other two watersheds. Working with local resource managers, we have identified a focal area for product development and validation for each watershed and its associated local reefs. This poster will present preliminary results and identify a path forward to ensure marine resource managers understand and correctly use the new ocean color products, and to help NOAA CRW refine its satellite products to maximize their benefit to coral reef management. NOAA - National Oceanic and Atmospheric Administration NESDIS - NOAA/National Environmental Satellite, Data, and Information Service S-NPP - Suomi National Polar-orbiting Partnership

Responses of the Metabolism of the Larvae of Pocillopora damicornis to Ocean Acidification and Warming

PubMed Central

Rivest, Emily B.; Hofmann, Gretchen E.

2014-01-01

Ocean acidification and warming are expected to threaten the persistence of tropical coral reef ecosystems. As coral reefs face multiple stressors, the distribution and abundance of corals will depend on the successful dispersal and settlement of coral larvae under changing environmental conditions. To explore this scenario, we used metabolic rate, at holobiont and molecular levels, as an index for assessing the physiological plasticity of Pocillopora damicornis larvae from this site to conditions of ocean acidity and warming. Larvae were incubated for 6 hours in seawater containing combinations of CO2 concentration (450 and 950 µatm) and temperature (28 and 30°C). Rates of larval oxygen consumption were higher at elevated temperatures. In contrast, high CO2 levels elicited depressed metabolic rates, especially for larvae released later in the spawning period. Rates of citrate synthase, a rate-limiting enzyme in aerobic metabolism, suggested a biochemical limit for increasing oxidative capacity in coral larvae in a warming, acidifying ocean. Biological responses were also compared between larvae released from adult colonies on the same day (cohorts). The metabolic physiology of Pocillopora damicornis larvae varied significantly by day of release. Additionally, we used environmental data collected on a reef in Moorea, French Polynesia to provide information about what adult corals and larvae may currently experience in the field. An autonomous pH sensor provided a continuous time series of pH on the natal fringing reef. In February/March, 2011, pH values averaged 8.075±0.023. Our results suggest that without adaptation or acclimatization, only a portion of naïve Pocillopora damicornis larvae may have suitable metabolic phenotypes for maintaining function and fitness in an end-of-the century ocean. PMID:24769774

Responses of the metabolism of the larvae of Pocillopora damicornis to ocean acidification and warming.

PubMed

Rivest, Emily B; Hofmann, Gretchen E

2014-01-01

Ocean acidification and warming are expected to threaten the persistence of tropical coral reef ecosystems. As coral reefs face multiple stressors, the distribution and abundance of corals will depend on the successful dispersal and settlement of coral larvae under changing environmental conditions. To explore this scenario, we used metabolic rate, at holobiont and molecular levels, as an index for assessing the physiological plasticity of Pocillopora damicornis larvae from this site to conditions of ocean acidity and warming. Larvae were incubated for 6 hours in seawater containing combinations of CO2 concentration (450 and 950 µatm) and temperature (28 and 30°C). Rates of larval oxygen consumption were higher at elevated temperatures. In contrast, high CO2 levels elicited depressed metabolic rates, especially for larvae released later in the spawning period. Rates of citrate synthase, a rate-limiting enzyme in aerobic metabolism, suggested a biochemical limit for increasing oxidative capacity in coral larvae in a warming, acidifying ocean. Biological responses were also compared between larvae released from adult colonies on the same day (cohorts). The metabolic physiology of Pocillopora damicornis larvae varied significantly by day of release. Additionally, we used environmental data collected on a reef in Moorea, French Polynesia to provide information about what adult corals and larvae may currently experience in the field. An autonomous pH sensor provided a continuous time series of pH on the natal fringing reef. In February/March, 2011, pH values averaged 8.075 ± 0.023. Our results suggest that without adaptation or acclimatization, only a portion of naïve Pocillopora damicornis larvae may have suitable metabolic phenotypes for maintaining function and fitness in an end-of-the century ocean.

Sperm dispersal distances estimated by parentage analysis in a brooding scleractinian coral.

PubMed

Warner, Patricia A; Willis, Bette L; van Oppen, Madeleine J H

2016-03-01

Within populations of brooding sessile corals, sperm dispersal constitutes the mechanism by which gametes interact and mating occurs, and forms the first link in the network of processes that determine specieswide connectivity patterns. However, almost nothing is known about sperm dispersal for any internally fertilizing coral. In this study, we conducted a parentage analysis on coral larvae collected from an area of mapped colonies, to measure the distance sperm disperses for the first time in a reef-building coral and estimated the mating system characteristics of a recently identified putative cryptic species within the Seriatopora hystrix complex (ShA; Warner et al. 2015). We defined consensus criteria among several replicated methods (COLONY 2.0, CERVUS 3.0, MLTR v3.2) to maximize accuracy in paternity assignments. Thirteen progeny arrays indicated that this putative species produces exclusively sexually derived, primarily outcrossed larvae (mean t(m) = 0.999) in multiple paternity broods (mean r(p) = 0.119). Self-fertilization was directly detected at low frequency for all broods combined (2.8%), but comprised 23% of matings in one brood. Although over 82% of mating occurred between colonies within 10 m of each other (mean sperm dispersal = 5.5 m ± 4.37 SD), we found no evidence of inbreeding in the established population. Restricted dispersal of sperm compared to slightly greater larval dispersal appears to limit inbreeding among close relatives in this cryptic species. Our findings establish a good basis for further work on sperm dispersal in brooding corals and provide the first information about the mating system of a newly identified and abundant cryptic species. © 2016 John Wiley & Sons Ltd.

Dietary supplementation with vitamin k affects transcriptome and proteome of Senegalese sole, improving larval performance and quality.

PubMed

Richard, Nadège; Fernández, Ignacio; Wulff, Tune; Hamre, Kristin; Cancela, Leonor; Conceição, Luis E C; Gavaia, Paulo J

2014-10-01

Nutritional factors strongly influence fish larval development and skeletogenesis, and may induce skeletal deformities. Vitamin K (VK) has been largely disregarded in aquaculture nutrition, despite its important roles in bone metabolism, in γ-carboxylation of Gla proteins, and in regulating gene expression through the pregnane X receptor (Pxr). Since the mechanisms mediating VK effects over skeletal development are poorly known, we investigated the effects of VK-supplementation on skeletal development in Senegalese sole larvae, aiming to identify molecular pathways involved. Larvae were fed live preys enriched with graded levels of phylloquinone (PK) (0, 50, and 250 mg kg(-1)) and survival rate, growth, VK contents, calcium content and incidence of skeletal deformities were determined, revealing an improvement of larval performance and decreasing the incidence of deformities in VK-supplemented groups. Comparative proteome analysis revealed a number of differentially expressed proteins between Control and Diet 250 associated with key biological processes including skin, muscle, and bone development. Expression analysis showed that genes encoding proteins related to the VK cycle (ggcx, vkor), VK nuclear receptor (pxr), and VK-dependent proteins (VKDPs; oc1 and grp), were differentially expressed. This study highlights the potential benefits of increasing dietary VK levels in larval diets, and brings new insights on the mechanisms mediating the positive effects observed on larval performance and skeletal development.

Comparative Transcriptomic Analysis Reveals Candidate Genes and Pathways Involved in Larval Settlement of the Barnacle Megabalanus volcano.

PubMed

Yan, Guoyong; Zhang, Gen; Huang, Jiaomei; Lan, Yi; Sun, Jin; Zeng, Cong; Wang, Yong; Qian, Pei-Yuan; He, Lisheng

2017-10-27

Megabalanus barnacle is one of the model organisms for marine biofouling research. However, further elucidation of molecular mechanisms underlying larval settlement has been hindered due to the lack of genomic information thus far. In the present study, cDNA libraries were constructed for cyprids, the key stage for larval settlement, and adults of Megabalanus volcano . After high-throughput sequencing and de novo assembly, 42,620 unigenes were obtained with a N50 value of 1532 bp. These unigenes were annotated by blasting against the NCBI non-redundant (nr), Swiss-Prot, Cluster of Orthologous Groups (COG), and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Finally, 19,522, 15,691, 14,459, and 10,914 unigenes were identified correspondingly. There were 22,158 differentially expressed genes (DEGs) identified between two stages. Compared with the cyprid stage, 8241 unigenes were down-regulated and 13,917 unigenes were up-regulated at the adult stage. The neuroactive ligand-receptor interaction pathway (ko04080) was significantly enriched by KEGG enrichment analysis of the DEGs, suggesting that it possibly involved in larval settlement. Potential functions of three conserved allatostatin neuropeptide-receptor pairs and two light-sensitive opsin proteins were further characterized, indicating that they might regulate attachment and metamorphosis at cyprid stage. These results provided a deeper insight into the molecular mechanisms underlying larval settlement of barnacles.

Comparative Transcriptomic Analysis Reveals Candidate Genes and Pathways Involved in Larval Settlement of the Barnacle Megabalanus volcano

PubMed Central

Yan, Guoyong; Huang, Jiaomei; Lan, Yi; Zeng, Cong; Wang, Yong; Qian, Pei-Yuan; He, Lisheng

2017-01-01

Megabalanus barnacle is one of the model organisms for marine biofouling research. However, further elucidation of molecular mechanisms underlying larval settlement has been hindered due to the lack of genomic information thus far. In the present study, cDNA libraries were constructed for cyprids, the key stage for larval settlement, and adults of Megabalanus volcano. After high-throughput sequencing and de novo assembly, 42,620 unigenes were obtained with a N50 value of 1532 bp. These unigenes were annotated by blasting against the NCBI non-redundant (nr), Swiss-Prot, Cluster of Orthologous Groups (COG), and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Finally, 19,522, 15,691, 14,459, and 10,914 unigenes were identified correspondingly. There were 22,158 differentially expressed genes (DEGs) identified between two stages. Compared with the cyprid stage, 8241 unigenes were down-regulated and 13,917 unigenes were up-regulated at the adult stage. The neuroactive ligand-receptor interaction pathway (ko04080) was significantly enriched by KEGG enrichment analysis of the DEGs, suggesting that it possibly involved in larval settlement. Potential functions of three conserved allatostatin neuropeptide-receptor pairs and two light-sensitive opsin proteins were further characterized, indicating that they might regulate attachment and metamorphosis at cyprid stage. These results provided a deeper insight into the molecular mechanisms underlying larval settlement of barnacles. PMID:29077039

RNA-Seq Reveals Extensive Transcriptional Response to Heat Stress in the Stony Coral Galaxea fascicularis

PubMed Central

Hou, Jing; Xu, Tao; Su, Dingjia; Wu, Ying; Cheng, Li; Wang, Jun; Zhou, Zhi; Wang, Yan

2018-01-01

Galaxea fascicularis, a stony coral belonging to family Oculinidae, is widely distributed in Red Sea, the Gulf of Aden and large areas of the Indo-Pacific oceans. So far there is a lack of gene expression knowledge concerning this massive coral. In the present study, G. fascicularis was subjected to heat stress at 32.0 ± 0.5°C in the lab, we found that the density of symbiotic zooxanthellae decreased significantly; meanwhile apparent bleaching and tissue lysing were observed at 10 h and 18 h after heat stress. The transcriptome responses were investigated in the stony coral G. fascicularis during heat bleaching using RNA-seq. A total of 42,028 coral genes were assembled from over 439 million reads. Gene expressions were compared at 10 and 18 h after heat stress. The significantly upregulated genes found in the Control_10h vs. Heat_10h comparison, presented mainly in GO terms related with DNA integration and unfolded protein response; and for the Control_18h vs. Heat_18h comparison, the GO terms include DNA integration. In addition, comparison between groups of Control_10h vs. Heat_10h and Control_18h vs. Heat_18h revealed that 125 genes were significantly upregulated in common between the two groups, whereas 21 genes were significantly downregulated in common, all these differentially expressed genes were found to be involved in stress response, DNA integration and unfolded protein response. Taken together, our results suggest that high temperature could activate the stress response at the early stage, and subsequently induce the bleaching and lysing through DNA integration and unfolded protein response, which are able to disrupt the balance of coral-zooxanthella symbiosis in the stony coral G. fascicularis. PMID:29487614

Quantifying coastal connectivity of coral spawn and larvae around Ryukyu Islands in the East China Sea

NASA Astrophysics Data System (ADS)

Odani, S.; Uchiyama, Y.; Kashima, M.; Kamidaira, Y.; Mitarai, S.

2016-12-01

Ryukyu Islands in the East China Sea are in a subtropical climate, hosting desirable environment for abundant coral ecosystem. Okinawa Main Island is the most densely populated island among them with tremendous tourist attractions including enchanting coral reefs and beaches. Kamidaira et al. (2016) suggested that the Kuroshio warm water maintains warmer water temperature favorable to corals around the island due mainly to intermittent eddy heat transport. It is presumed that the Kuroshio and associated eddy mixing also promote the transport and dispersal of coral spawn and larvae across the islands, whereas the area has suffered from coral breeching in the recent decades. Therefore, for optimal preservation and protection of the coral habitats around Ryukyu Island, we conduct a double nested high-resolution synoptic ocean modeling using ROMS with grid spacing down to 1 km coupled with an offline Lagrangian particle tracking model to investigate dispersal of coral spawn and larvae released from about 20 major islands and lagoons. Based on the model outcome, we quantify connectivity using Lagrangian probability density functions (PDFs) of the Lagrangian particles (e.g., Mitarai et al., 2009) among Ryukyu Islands. We then focus on the larval dispersal released from Sekisei Lagoon in Yaeyama Islands close to Taiwan, where we have carried out a series of in-situ surface drifter measurement. To compare the observation with the model, 160 source and sink patches with a diameter of 3 km are defined around Sekisei Lagoon and Okinawa Main Island for quantification of the detailed connectivity between them. The advection time is assumed for no more than 3 weeks to represent the lifespan of coral spawn and larvae. A PDF analysis suggests that the particles mostly remain near the released areas with predominant clockwise circulation around the lagoon, while approximately less than 5 % of particles are trapped and transported northeastward in long distance by the Kuroshio. The trajectories show that some of these particles are transported to approach Okinawa Main Island while some are trapped by eddies between the Kuroshio and the island, suggesting that eddies act to promote both particle beaching on the islands as well as trapping in the offshore.

Larval traits carry over to affect post-settlement behaviour in a common coral reef fish.

PubMed

Dingeldein, Andrea L; White, J Wilson

2016-07-01

Most reef fishes begin life as planktonic larvae before settling to the reef, metamorphosing and entering the benthic adult population. Different selective forces determine survival in the planktonic and benthic life stages, but traits established in the larval stage may carry over to affect post-settlement performance. We tested the hypothesis that larval traits affect two key post-settlement fish behaviours: social group-joining and foraging. Certain larval traits of reef fishes are permanently recorded in the rings in their otoliths. In the bluehead wrasse (Thalassoma bifasciatum), prior work has shown that key larval traits recorded in otoliths (growth rate, energetic condition at settlement) carry over to affect post-settlement survival on the reef, with higher-larval-condition fish experiencing less post-settlement mortality. We hypothesized that this selective mortality is mediated by carry-over effects on post-settlement antipredator behaviours. We predicted that better-condition fish would forage less and be more likely to join groups, both behaviours that would reduce predation risk. We collected 550 recently settled bluehead wrasse (Thalassoma bifasciatum) from three reef sites off St. Croix (USVI) and performed two analyses. First, we compared each settler's larval traits to the size of its social group to determine whether larval traits influenced group-joining behaviour. Secondly, we observed foraging behaviour in a subset of grouped and solitary fish (n = 14) for 1-4 days post-settlement. We then collected the fish and tested whether larval traits influenced the proportion of time spent foraging. Body length at settlement, but not condition, affected group-joining behaviour; smaller fish were more likely to remain solitary or in smaller groups. However, both greater length and better condition were associated with greater proportions of time spent foraging over four consecutive days post-settlement. Larval traits carry over to affect post-settlement behaviour, although not as we expected: higher quality larvae join groups more frequently (safer) but then forage more. Foraging is risky but may allow faster post-settlement growth, reducing mortality risk in the long run. This shows that behaviour likely serves as a mechanistic link connecting larval traits to post-settlement selective mortality. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

Living upside down: patterns of red coral settlement in a cave

PubMed Central

Rugiu, Luca; Cerrano, Carlo; Abbiati, Marco

2018-01-01

Background Larval settlement and intra-specific interactions during the recruitment phase are crucial in determining the distribution and density of sessile marine populations. Marine caves are confined and stable habitats. As such, they provide a natural laboratory to study the settlement and recruitment processes in sessile invertebrates, including the valuable Mediterranean red coral Corallium rubrum. In the present study, the spatial and temporal variability of red coral settlers in an underwater cave was investigated by demographic and genetic approaches. Methods Sixteen PVC tiles were positioned on the walls and ceiling of the Colombara Cave, Ligurian Sea, and recovered after twenty months. A total of 372 individuals of red coral belonging to two different reproductive events were recorded. Basal diameter, height, and number of polyps were measured, and seven microsatellites loci were used to evaluate the genetic relationships among individuals and the genetic structure. Results Significant differences in the colonization rate were observed both between the two temporal cohorts and between ceiling and walls. No genetic structuring was observed between cohorts. Overall, high levels of relatedness among individuals were found. Conclusion The results show that C. rubrumindividuals on tiles are highly related at very small spatial scales, suggesting that nearby recruits are likely to be sibs. Self-recruitment and the synchronous settlement of clouds of larvae could be possible explanations for the observed pattern. PMID:29844950

Quantifying Spatial Genetic Structuring in Mesophotic Populations of the Precious Coral Corallium rubrum

PubMed Central

Costantini, Federica; Carlesi, Lorenzo; Abbiati, Marco

2013-01-01

While shallow water red coral populations have been overharvested in the past, nowadays, commercial harvesting shifted its pressure on mesophotic organisms. An understanding of red coral population structure, particularly larval dispersal patterns and connectivity among harvested populations is paramount to the viability of the species. In order to determine patterns of genetic spatial structuring of deep water Corallium rubrum populations, for the first time, colonies found between 58–118 m depth within the Tyrrhenian Sea were collected and analyzed. Ten microsatellite loci and two regions of mitochondrial DNA (mtMSH and mtC) were used to quantify patterns of genetic diversity within populations and to define population structuring at spatial scales from tens of metres to hundreds of kilometres. Microsatellites showed heterozygote deficiencies in all populations. Significant levels of genetic differentiation were observed at all investigated spatial scales, suggesting that populations are likely to be isolated. This differentiation may by the results of biological interactions, occurring within a small spatial scale and/or abiotic factors acting at a larger scale. Mitochondrial markers revealed significant genetic structuring at spatial scales greater then 100 km showing the occurrence of a barrier to gene flow between northern and southern Tyrrhenian populations. These findings provide support for the establishment of marine protected areas in the deep sea and off-shore reefs, in order to effectively maintain genetic diversity of mesophotic red coral populations. PMID:23646109

Quantifying spatial genetic structuring in mesophotic populations of the precious coral Corallium rubrum.

PubMed

Costantini, Federica; Carlesi, Lorenzo; Abbiati, Marco

2013-01-01

While shallow water red coral populations have been overharvested in the past, nowadays, commercial harvesting shifted its pressure on mesophotic organisms. An understanding of red coral population structure, particularly larval dispersal patterns and connectivity among harvested populations is paramount to the viability of the species. In order to determine patterns of genetic spatial structuring of deep water Corallium rubrum populations, for the first time, colonies found between 58-118 m depth within the Tyrrhenian Sea were collected and analyzed. Ten microsatellite loci and two regions of mitochondrial DNA (mtMSH and mtC) were used to quantify patterns of genetic diversity within populations and to define population structuring at spatial scales from tens of metres to hundreds of kilometres. Microsatellites showed heterozygote deficiencies in all populations. Significant levels of genetic differentiation were observed at all investigated spatial scales, suggesting that populations are likely to be isolated. This differentiation may by the results of biological interactions, occurring within a small spatial scale and/or abiotic factors acting at a larger scale. Mitochondrial markers revealed significant genetic structuring at spatial scales greater then 100 km showing the occurrence of a barrier to gene flow between northern and southern Tyrrhenian populations. These findings provide support for the establishment of marine protected areas in the deep sea and off-shore reefs, in order to effectively maintain genetic diversity of mesophotic red coral populations.

Diversity of trypanorhynch metacestodes in teleost fishes from coral reefs off eastern Australia and New Caledonia

PubMed Central

Beveridge, Ian; Bray, Rodney A.; Cribb, Thomas H.; Justine, Jean-Lou

2014-01-01

Trypanorhynch metacestodes were examined from teleosts from coral reefs in eastern Australia and from New Caledonia. From over 12,000 fishes examined, 33 named species of trypanorhynchs were recovered as well as three species of tentacularioids which are described but not named. Host-parasite and parasite-host lists are provided, including more than 100 new host records. Lacistorhynchoid and tentacularioid taxa predominated with fewer otobothrioid and gymnorhynchoids. Five species, Callitetrarhynchus gracilis, Floriceps minacanthus, Pseudotobothrium dipsacum, Pseudolacistorhynchus heroniensis and Ps. shipleyi, were particularly common and exhibited low host specificity. Limited data suggested a higher diversity of larval trypanorhynchs in larger piscivorous fish families. Several fish families surveyed extensively (Blenniidae, Chaetodontidae, Gobiidae, Kyphosidae and Scaridae) yielded no trypanorhynch larvae. The overall similarity between the fauna of the Great Barrier Reef and New Caledonia was 45%. Where available, information on the adult stages in elasmobranchs has been included. PMID:25402635

Fishery consequences of marine reserves: short-term pain for longer-term gain.

PubMed

Hopf, Jess K; Jones, Geoffrey P; Williamson, David H; Connolly, Sean R

2016-04-01

Marine reserves are often established in areas that support fisheries. Larval export from reserves is argued to help compensate for the loss of fishable habitat; however, previous modeling studies have focused on long-term equilibrium outcomes. We examined the transient consequences of reserve establishment for fished metapopulations, considering both a well-mixed larval pool and a spatially explicit model based on a coral trout (Plectropomus spp.) metapopulation. When fishing pressure was reallocated relative to the area protected, yields decreased initially, then recovered, and ultimately exceeded pre-reserve levels. However, recovery time was on the order of several years to decades. If fishing pressure intensified to maintain pre-reserve yields, reserves were sometimes unable to support the increased mortality and the metapopulation collapsed. This was more likely when reserves were small, or located peripherally within the metapopulation. Overall, reserves can achieve positive conservation and fishery benefits, but fisheries management complementary to reserve implementation is essential.

High natural gene expression variation in the reef-building coral Acropora millepora: potential for acclimative and adaptive plasticity

PubMed Central

2013-01-01

Background Ecosystems worldwide are suffering the consequences of anthropogenic impact. The diverse ecosystem of coral reefs, for example, are globally threatened by increases in sea surface temperatures due to global warming. Studies to date have focused on determining genetic diversity, the sequence variability of genes in a species, as a proxy to estimate and predict the potential adaptive response of coral populations to environmental changes linked to climate changes. However, the examination of natural gene expression variation has received less attention. This variation has been implicated as an important factor in evolutionary processes, upon which natural selection can act. Results We acclimatized coral nubbins from six colonies of the reef-building coral Acropora millepora to a common garden in Heron Island (Great Barrier Reef, GBR) for a period of four weeks to remove any site-specific environmental effects on the physiology of the coral nubbins. By using a cDNA microarray platform, we detected a high level of gene expression variation, with 17% (488) of the unigenes differentially expressed across coral nubbins of the six colonies (jsFDR-corrected, p < 0.01). Among the main categories of biological processes found differentially expressed were transport, translation, response to stimulus, oxidation-reduction processes, and apoptosis. We found that the transcriptional profiles did not correspond to the genotype of the colony characterized using either an intron of the carbonic anhydrase gene or microsatellite loci markers. Conclusion Our results provide evidence of the high inter-colony variation in A. millepora at the transcriptomic level grown under a common garden and without a correspondence with genotypic identity. This finding brings to our attention the importance of taking into account natural variation between reef corals when assessing experimental gene expression differences. The high transcriptional variation detected in this study is interpreted and discussed within the context of adaptive potential and phenotypic plasticity of reef corals. Whether this variation will allow coral reefs to survive to current challenges remains unknown. PMID:23565725

Metatranscriptome Sequencing of a Reef-building Coral Elucidates Holobiont Community Gene Functions in Health and Disease

NASA Astrophysics Data System (ADS)

Timberlake, S.; Helbig, T.; Fernando, S.; Penn, K.; Alm, E.; Thompson, F.; Thompson, J. R.

2012-12-01

The coral reefs of the Abrolhos Bank of Brazil play a vital ecological role in the health of the Southern Atlantic Ocean, but accelerating rates of disease, particularly white plague, threaten this ecosystem. Thus, an understanding of white plague disease and diagnostic tests for it are urgently needed. The coral animal is associated with a distinct microbiome, a diverse assemblage of eukaryotes, bacteria, and viruses. That these microbes have a great influence on the health of the coral has been long known, however, most of their functions are still mysterious. While recent studies have contrasted healthy and white-plague-associated communities, the causative agents and mechanisms of the disease remain unknown. We collected fragments of healthy and diseased corals, as well as post-disease skeleton, from 12 colonies of the genus Mussismilia, the major component of the reef structure in the Abrolhos bank, and increasingly, a victim of white-plague disease. Fragments were flash-frozen in situ, and prepped for culture-free high throughput sequencing of gene transcripts with the Illumina II-G. While the membership of the microbial communities associated with coral has been previously described, the a coral holobiont community's gene function has, to date, never been assayed by this powerful approach. We designed a bioinformatics pipeline to analyze the short-read data from this complex sample: identifying the functions of genes expressed in the holobiont, and describing the active community's taxonomic composition. We show that gene functions expressed by the coral's bacterial assemblage are distinct from those of the underlying skeleton, and we highlight differences in the disease samples. We find that gene markers for the dissimilatory sulfate reduction pathway more abundant in the disease state, and we further quantify this difference with qPCR. Finally, we report the abundant expression of highly repetitive transcripts in the diseased coral samples, and highlight other coral host genes whose expression differs in this disease. Our work provides a first glimpse into coral holobiont community gene function and its deviations in disease. Moreover, we hope that our bioinformatic protocol, designed to cope with the challenges of short-read transcriptomics from complex ecosystems with no close reference, will be a useful template to further understanding of the gene functions and ecological partnerships in coral reefs and other complex ecosystems.

Deep sequencing-based transcriptome analysis of Plutella xylostella larvae parasitized by Diadegma semiclausum

PubMed Central

2011-01-01

Background Parasitoid insects manipulate their hosts' physiology by injecting various factors into their host upon parasitization. Transcriptomic approaches provide a powerful approach to study insect host-parasitoid interactions at the molecular level. In order to investigate the effects of parasitization by an ichneumonid wasp (Diadegma semiclausum) on the host (Plutella xylostella), the larval transcriptome profile was analyzed using a short-read deep sequencing method (Illumina). Symbiotic polydnaviruses (PDVs) associated with ichneumonid parasitoids, known as ichnoviruses, play significant roles in host immune suppression and developmental regulation. In the current study, D. semiclausum ichnovirus (DsIV) genes expressed in P. xylostella were identified and their sequences compared with other reported PDVs. Five of these genes encode proteins of unknown identity, that have not previously been reported. Results De novo assembly of cDNA sequence data generated 172,660 contigs between 100 and 10000 bp in length; with 35% of > 200 bp in length. Parasitization had significant impacts on expression levels of 928 identified insect host transcripts. Gene ontology data illustrated that the majority of the differentially expressed genes are involved in binding, catalytic activity, and metabolic and cellular processes. In addition, the results show that transcription levels of antimicrobial peptides, such as gloverin, cecropin E and lysozyme, were up-regulated after parasitism. Expression of ichnovirus genes were detected in parasitized larvae with 19 unique sequences identified from five PDV gene families including vankyrin, viral innexin, repeat elements, a cysteine-rich motif, and polar residue rich protein. Vankyrin 1 and repeat element 1 genes showed the highest transcription levels among the DsIV genes. Conclusion This study provides detailed information on differential expression of P. xylostella larval genes following parasitization, DsIV genes expressed in the host and also improves our current understanding of this host-parasitoid interaction. PMID:21906285

No gene flow across the Eastern Pacific Barrier in the reef-building coral Porites lobata.

PubMed

Baums, Iliana B; Boulay, Jennifer N; Polato, Nicholas R; Hellberg, Michael E

2012-11-01

The expanse of deep water between the central Pacific islands and the continental shelf of the Eastern Tropical Pacific is regarded as the world's most potent marine biogeographic barrier. During recurrent climatic fluctuations (ENSO, El Niño Southern Oscillation), however, changes in water temperature and the speed and direction of currents become favourable for trans-oceanic dispersal of larvae from central Pacific to marginal eastern Pacific reefs. Here, we investigate the population connectivity of the reef-building coral Porites lobata across the Eastern Pacific Barrier (EPB). Patterns of recent gene flow in samples (n = 1173) from the central Pacific and the Eastern Tropical Pacific (ETP) were analysed with 12 microsatellite loci. Results indicated that P. lobata from the ETP are strongly isolated from those in the central Pacific and Hawaii (F(ct) ' = 0.509; P < 0.001). However, samples from Clipperton Atoll, an oceanic island on the eastern side of the EPB, grouped with the central Pacific. Within the central Pacific, Hawaiian populations were strongly isolated from three co-occurring clusters found throughout the remainder of the central Pacific. No further substructure was evident in the ETP. Changes in oceanographic conditions during ENSO over the past several thousand years thus appear insufficient to support larval deliveries from the central Pacific to the ETP or strong postsettlement selection acts on ETP settlers from the central Pacific. Recovery of P. lobata populations in the frequently disturbed ETP thus must depend on local larval sources. © 2012 Blackwell Publishing Ltd.

Potent Antifouling Marine Dihydroquinolin-2(1H)-one-Containing Alkaloids from the Gorgonian Coral-Derived Fungus Scopulariopsis sp.

PubMed

Shao, Chang-Lun; Xu, Ru-Fang; Wang, Chang-Yun; Qian, Pei-Yuan; Wang, Kai-Ling; Wei, Mei-Yan

2015-08-01

Marine biofouling has a major economic impact, especially when it occurs on ship hulls or aquaculture facilities. Since the International Maritime Organization (IMO) treaty to ban the application of organotin-based paints to ships went into effect in 2008, there is an urgent demand for the development of efficient and environmentally friendly antifouling agents. Marine microorganisms have proved to be a potential source of antifouling natural compounds. In this study, six dihydroquinolin-2-one-containing alkaloids, three monoterpenoids combined with a 4-phenyl-3,4-dihydroquinolin-2(1H)-one (1-3) and three 4-phenyl-3,4-dihydroquinolin-2(1H)-one alkaloids (4-6), were isolated from the gorgonian coral-derived fungus Scopulariopsis sp. collected in the South China Sea. These dihydroquinolin-2-one-containing alkaloids were evaluated against the larval settlement of barnacle Balanus amphitrite, and antifouling activity was detected for the first time for this class of metabolites. All of them except 6 showed strong antifouling activity. Compounds 1 and 2 were discovered to be the most promising non-toxic antilarval settlement candidates. Especially, compound 1 is the strongest antifouling compound in nature until now which showed highly potent activity with picomolar level (EC50 17.5 pM) and a very safety and high therapeutic ratio (LC50/EC50 1200). This represents an effective non-toxic, anti-larval settlement structural class of promising antifouling lead compound.

Comparative Transcriptome Analyses Uncover Key Candidate Genes Mediating Flight Capacity in Bactrocera dorsalis (Hendel) and Bactrocera correcta (Bezzi) (Diptera: Tephritidae).

PubMed

Guo, Shaokun; Zhao, Zihua; Liu, Lijun; Li, Zhihong; Shen, Jie

2018-01-30

Flight capacity is important for invasive pests during entry, establishment and spreading. Both Bactrocera dorsalis Hendel and Bactrocera correcta Bezzi are invasive fruit flies but their flight capacities differ. Here, a tethered flight mill test demonstrated that B. dorsalis exhibits a greater flight capacity than B. correcta . RNA-Seq was used to determine the transcriptomic differences associated with the flight capacity of two Bactrocera species. Transcriptome data showed that 6392 unigenes were differentially expressed between the two species in the larval stage, whereas in the adult stage, 4104 differentially expressed genes (DEGs) were identified in females, and 3445 DEGs were observed in males. The flight capacity appeared to be correlated with changes in the transcriptional levels of genes involved in wing formation, flight muscle structure, energy metabolism, and hormonal control. Using RNA interference (RNAi) to verify the function of one DEG, the epidermal growth factor receptor ( EGFR ), we confirmed the role of this gene in regulating wing development, and thereby flight capacity, in both species. This work reveals the flight mechanism of fruit flies and provides insight into fundamental transcriptomics for further studies on the flight performance of insects.

Comparative Transcriptome Analyses Uncover Key Candidate Genes Mediating Flight Capacity in Bactrocera dorsalis (Hendel) and Bactrocera correcta (Bezzi) (Diptera: Tephritidae)

PubMed Central

Zhao, Zihua; Liu, Lijun; Li, Zhihong; Shen, Jie

2018-01-01

Flight capacity is important for invasive pests during entry, establishment and spreading. Both Bactrocera dorsalis Hendel and Bactrocera correcta Bezzi are invasive fruit flies but their flight capacities differ. Here, a tethered flight mill test demonstrated that B. dorsalis exhibits a greater flight capacity than B. correcta. RNA-Seq was used to determine the transcriptomic differences associated with the flight capacity of two Bactrocera species. Transcriptome data showed that 6392 unigenes were differentially expressed between the two species in the larval stage, whereas in the adult stage, 4104 differentially expressed genes (DEGs) were identified in females, and 3445 DEGs were observed in males. The flight capacity appeared to be correlated with changes in the transcriptional levels of genes involved in wing formation, flight muscle structure, energy metabolism, and hormonal control. Using RNA interference (RNAi) to verify the function of one DEG, the epidermal growth factor receptor (EGFR), we confirmed the role of this gene in regulating wing development, and thereby flight capacity, in both species. This work reveals the flight mechanism of fruit flies and provides insight into fundamental transcriptomics for further studies on the flight performance of insects. PMID:29385681

The developmental transcriptome atlas of the spoon worm Urechis unicinctus (Echiurida: Annelida).

PubMed

Park, Chungoo; Han, Yong-Hee; Lee, Sung-Gwon; Ry, Kyoung-Bin; Oh, Jooseong; Kern, Elizabeth M A; Park, Joong-Ki; Cho, Sung-Jin

2018-03-01

Echiurida is one of the most intriguing major subgroups of annelida because, unlike most other annelids, echiurids lack metameric body segmentation as adults. For this reason, transcriptome analyses from various developmental stages of echiurid species can be of substantial value for understanding precise expression levels and the complex regulatory networks during early and larval development. A total of 914 million raw RNA-Seq reads were produced from 14 developmental stages of Urechis unicinctus and were de novo assembled into contigs spanning 63,928,225 bp with an N50 length of 2700 bp. The resulting comprehensive transcriptome database of the early developmental stages of U. unicinctus consists of 20,305 representative functional protein-coding transcripts. Approximately 66% of unigenes were assigned to superphylum-level taxa, including Lophotrochozoa (40%). The completeness of the transcriptome assembly was assessed using benchmarking universal single-copy orthologs; 75.7% of the single-copy orthologs were presented in our transcriptome database. We observed 3 distinct patterns of global transcriptome profiles from 14 developmental stages and identified 12,705 genes that showed dynamic regulation patterns during the differentiation and maturation of U. unicinctus cells. We present the first large-scale developmental transcriptome dataset of U. unicinctus and provide a general overview of the dynamics of global gene expression changes during its early developmental stages. The analysis of time-course gene expression data is a first step toward understanding the complex developmental gene regulatory networks in U. unicinctus and will furnish a valuable resource for analyzing the functions of gene repertoires in various developmental phases.

Climate change and the performance of larval coral reef fishes: the interaction between temperature and food availability

PubMed Central

McLeod, Ian M.; Rummer, Jodie L.; Clark, Timothy D.; Jones, Geoffrey P.; McCormick, Mark I.; Wenger, Amelia S.; Munday, Philip L.

2013-01-01

Climate-change models predict that tropical ocean temperatures will increase by 2–3°C this century and affect plankton communities that are food for marine fish larvae. Both temperature and food supply can influence development time, growth, and metabolism of marine fishes, particularly during larval stages. However, little is known of the relative importance and potential interacting effects of ocean warming and changes to food supply on the performance of larval fishes. We tested this for larvae of the coral reef anemonefish, Amphiprion percula, in an orthogonal experiment comprising three temperatures and three feeding schedules. Temperatures were chosen to represent present-day summer averages (29.2°C) and end-of-century climate change projections of +1.5°C (30.7°C) and +3°C (32.2°C). Feeding schedules were chosen to represent a reduction in access to food (fed daily, every 2 days, or every 3 days). Overall, larvae took longer to settle at higher temperatures and with less frequent feeding, and there was a significant interaction between these factors. Time to metamorphosis was fastest in the 30.7oC and high food availability treatment (10.5 ± 0.2 days) and slowest in the 32.2oC and low food availability treatment (15.6 ± 0.5 days; i.e. 50% faster). Fish from the lower feeding regimens had a lower body condition and decreased survivorship to metamorphosis. Routine oxygen consumption rates were highest for fish raised at 32.2°C and fed every third day (162 ± 107 mg O2  kg−1 h−1) and lowest for fish raised at 29.2°C and fed daily (122 ± 101 mg O2 kg−1 h−1; i.e. 35% lower). The elevated routine oxygen consumption rate, and therefore greater energy use at higher temperatures, may leave less energy available for growth and development, resulting in the longer time to metamorphosis. Overall, these results suggest that larval fishes will be severely impacted by climate-change scenarios that predict both elevated temperatures and reduced food supply. PMID:27293608

Climate change and the performance of larval coral reef fishes: the interaction between temperature and food availability.

PubMed

McLeod, Ian M; Rummer, Jodie L; Clark, Timothy D; Jones, Geoffrey P; McCormick, Mark I; Wenger, Amelia S; Munday, Philip L

2013-01-01

Climate-change models predict that tropical ocean temperatures will increase by 2-3°C this century and affect plankton communities that are food for marine fish larvae. Both temperature and food supply can influence development time, growth, and metabolism of marine fishes, particularly during larval stages. However, little is known of the relative importance and potential interacting effects of ocean warming and changes to food supply on the performance of larval fishes. We tested this for larvae of the coral reef anemonefish, Amphiprion percula, in an orthogonal experiment comprising three temperatures and three feeding schedules. Temperatures were chosen to represent present-day summer averages (29.2°C) and end-of-century climate change projections of +1.5°C (30.7°C) and +3°C (32.2°C). Feeding schedules were chosen to represent a reduction in access to food (fed daily, every 2 days, or every 3 days). Overall, larvae took longer to settle at higher temperatures and with less frequent feeding, and there was a significant interaction between these factors. Time to metamorphosis was fastest in the 30.7(o)C and high food availability treatment (10.5 ± 0.2 days) and slowest in the 32.2(o)C and low food availability treatment (15.6 ± 0.5 days; i.e. 50% faster). Fish from the lower feeding regimens had a lower body condition and decreased survivorship to metamorphosis. Routine oxygen consumption rates were highest for fish raised at 32.2°C and fed every third day (162 ± 107 mg O2  kg(-1) h(-1)) and lowest for fish raised at 29.2°C and fed daily (122 ± 101 mg O2 kg(-1) h(-1); i.e. 35% lower). The elevated routine oxygen consumption rate, and therefore greater energy use at higher temperatures, may leave less energy available for growth and development, resulting in the longer time to metamorphosis. Overall, these results suggest that larval fishes will be severely impacted by climate-change scenarios that predict both elevated temperatures and reduced food supply.

Whole-Body Single-Cell Sequencing Reveals Transcriptional Domains in the Annelid Larval Body

PubMed Central

Achim, Kaia; Eling, Nils; Vergara, Hernando Martinez; Bertucci, Paola Yanina; Musser, Jacob; Vopalensky, Pavel; Brunet, Thibaut; Collier, Paul; Benes, Vladimir; Marioni, John C; Arendt, Detlev

2018-01-01

Abstract Animal bodies comprise diverse arrays of cells. To characterize cellular identities across an entire body, we have compared the transcriptomes of single cells randomly picked from dissociated whole larvae of the marine annelid Platynereis dumerilii. We identify five transcriptionally distinct groups of differentiated cells, each expressing a unique set of transcription factors and effector genes that implement cellular phenotypes. Spatial mapping of cells into a cellular expression atlas, and wholemount in situ hybridization of group-specific genes reveals spatially coherent transcriptional domains in the larval body, comprising, for example, apical sensory-neurosecretory cells versus neural/epidermal surface cells. These domains represent new, basic subdivisions of the annelid body based entirely on differential gene expression, and are composed of multiple, transcriptionally similar cell types. They do not represent clonal domains, as revealed by developmental lineage analysis. We propose that the transcriptional domains that subdivide the annelid larval body represent families of related cell types that have arisen by evolutionary diversification. Their possible evolutionary conservation makes them a promising tool for evo–devo research. PMID:29373712

Reconnaissance dating: a new radiocarbon method applied to assessing the temporal distribution of Southern Ocean deep-sea corals

USGS Publications Warehouse

Burke, Andrea; Robinson, Laura F.; McNichol, Ann P.; Jenkins, William J.; Scanlon, Kathryn M.; Gerlach, Dana S.

2010-01-01

We have developed a rapid 'reconnaissance' method of preparing graphite for 14C/12C analysis. Carbonate (~15 mg) is combusted using an elemental analyzer and the resulting CO2 is converted to graphite using a sealed tube zinc reduction method. Over 85% (n=45 replicates on twenty-one individual corals) of reconnaissance ages measured on corals ranging in age from 500 to 33,000 radiocarbon years (Ryr) are within two standard deviations of ages generated using standard hydrolysis methods on the same corals, and all reconnaissance ages are within 300 Ryr of the standard hydrolysis ages. Replicate measurements on three individual aragonitic corals yielded ages of 1076±35 Ryr (standard deviation; n=5), 10,739±47 Ryr (n=8), and 40,146±3500 Ryr (n=9). No systematic biases were found using different cleaning methods or variable sample sizes. Analysis of 13C/12C was made concurrently with the 14C/12C measurement to correct for natural fractionation and for fractionation during sample processing and analysis. This technique provides a new, rapid method for making accurate, percent-level 14C/12C analyses that may be used to establish the rates and chronology of earth system processes where survey-type modes of age estimation are desirable. For example, applications may include creation of sediment core-top maps, preliminary age models for sediment cores, and growth rate studies of marine organisms such as corals or mollusks. We applied the reconnaissance method to more than 100 solitary deep-sea corals collected in the Drake Passage in the Southern Ocean to investigate their temporal and spatial distribution. The corals used in this study are part of a larger sample set, and the subset that was dated was chosen based on species as opposed to preservation state, so as to exclude obvious temporal biases. Similar to studies in other regions, the distribution of deep-sea corals is not constant through time across the Drake Passage. Most of the corals from the Burdwood Bank (continental shelf of Argentina) have ages ranging between 0 and 2500 calendar years, whereas most of the corals from the Sars Seamount in the Drake Passage have ages between 10,000 and 12,500 calendar years. Such differences may be caused in part by sampling biases, but may also be caused by changes in larval transport, nutrient supply, or other environmental pressures.

The biology and ecology of black corals (Cnidaria: Anthozoa: Hexacorallia: Antipatharia).

PubMed

Wagner, Daniel; Luck, Daniel G; Toonen, Robert J

2012-01-01

Antipatharians, commonly known as black corals, are treasured by many cultures for medicinal purposes and to produce jewellery. Despite their economic and cultural importance, very little is known about the basic biology and ecology of black corals because most species inhabit deeper-water environments (>50m) which are logistically challenging to study. There has been a recent increase of studies focusing on antipatharians; however, these have not yet been comprehensively reviewed. This literature review seeks to summarize the available information on the biology and ecology of antipatharians. Although black corals occur throughout all oceans and from subtidal to abyssal depths, they are particularly common in tropical and subtropical regions at depths below 50m. Antipatharians are generally found in areas with hard substrates, low-light and strong currents. Under favourable conditions, some black coral species form dense aggregations to the point of becoming ecologically dominant. Zooplankton appears to be the major component of the diet of black corals, which feed as suspension feeders and use mucus and nematocysts to capture their prey. Previously categorized as azooxanthellate corals, recent research has revealed that many antipatharians appear capable of harbouring symbionts, but unlike other corals, dinoflagellates of the genus Symbiodinium are generally not important to the nutrition of black corals. Antipatharians reproduce through both sexual and asexual processes. In general, polyps and colonies are gonochoric, with fertilization and larval development likely occurring externally; however, to date antipatharian larvae have only been observed for a single species. Antipatharians are generally slow-growing and long-lived organisms with maximum longevities ranging from decades to millennia. Black corals are more abundant with depth, a pattern which has been hypothesized to avoid competition with obligate photosynthetic fauna. Additionally, antipatharians may compete for space by using sweeper tentacles and secondary metabolites. With the exception of a few predators such as gastropods and green sea turtles, antipatharians appear to be little impacted by predation. Like other corals, antipatharians can be habitat engineers of importance to a myriad of associated organisms including arthropods, annelids, echinoderms, mollusks, sponges and cnidarians, several of which are adapted to live exclusively on black corals. Given that most black coral species inhabit remote environments, our understanding of these organisms will depend on our ability to effectively sample and study them. Future collections, particularly in deeper waters (>50m), will be needed to determine whether antipatharian species have limited biogeographical distributions or whether this has simply been an artefact of low sampling efforts away from population centres and taxonomic uncertainties within this group. Additionally, biological and ecological studies require increased sample sizes because most information is currently derived from the examination of only a handful of specimens. Copyright © 2012 Elsevier Ltd. All rights reserved.

Geographic differences in vertical connectivity in the Caribbean coral Montastraea cavernosa despite high levels of horizontal connectivity at shallow depths.

PubMed

Serrano, X; Baums, I B; O'Reilly, K; Smith, T B; Jones, R J; Shearer, T L; Nunes, F L D; Baker, A C

2014-09-01

The deep reef refugia hypothesis proposes that deep reefs can act as local recruitment sources for shallow reefs following disturbance. To test this hypothesis, nine polymorphic DNA microsatellite loci were developed and used to assess vertical connectivity in 583 coral colonies of the Caribbean depth-generalist coral Montastraea cavernosa. Samples were collected from three depth zones (≤10, 15-20 and ≥25 m) at sites in Florida (within the Upper Keys, Lower Keys and Dry Tortugas), Bermuda, and the U.S. Virgin Islands. Migration rates were estimated to determine the probability of coral larval migration from shallow to deep and from deep to shallow. Finally, algal symbiont (Symbiodinium spp.) diversity and distribution were assessed in a subset of corals to test whether symbiont depth zonation might indicate limited vertical connectivity. Overall, analyses revealed significant genetic differentiation by depth in Florida, but not in Bermuda or the U.S. Virgin Islands, despite high levels of horizontal connectivity between these geographic locations at shallow depths. Within Florida, greater vertical connectivity was observed in the Dry Tortugas compared to the Lower or Upper Keys. However, at all sites, and regardless of the extent of vertical connectivity, migration occurred asymmetrically, with greater likelihood of migration from shallow to intermediate/deep habitats. Finally, most colonies hosted a single Symbiodinium type (C3), ruling out symbiont depth zonation of the dominant symbiont type as a structuring factor. Together, these findings suggest that the potential for shallow reefs to recover from deep-water refugia in M. cavernosa is location-specific, varying among and within geographic locations likely as a consequence of local hydrology. © 2014 John Wiley & Sons Ltd.

Food availability and pCO2 impacts on planulation, juvenile survival, and calcification of the azooxanthellate scleractinian coral, Balanophyllia elegans

NASA Astrophysics Data System (ADS)

Crook, E. D.; Cooper, H.; Potts, D. C.; Lambert, T.; Paytan, A.

2013-05-01

Ocean acidification, the assimilation of atmospheric CO2 by the oceans that decreases the pH and CaCO3 saturation state (Ω) of seawater, is projected to have severe consequences for calcifying organisms. Strong evidence suggests that tropical reef-building corals containing algal symbionts (zooxanthellae) will experience dramatic declines in calcification over the next century. The responses of azooxanthellate corals to ocean acidification are less well understood, and because they cannot obtain extra photosynthetic energy from symbionts, they provide a system for studying the direct effects of acidification on the energy available for calcification. The orange cup coral Balanophyllia elegans is a solitary, azooxanthellate scleractinian species common on the California coast where it thrives in the low pH waters of an upwelling regime. During an 8 month study, we addressed the effects of three pCO2 treatments (410, 770, and 1230 μatm) and two feeding frequencies (High Food and Low Food) on adult Balanophyllia elegans planulation (larval release) rates, and on the survival, growth, and calcification of their juvenile offspring. Planulation rates were affected by food level but not pCO2, while juvenile survival was highest under 410 μatm and High Food conditions. Our results suggest that feeding rate has a greater impact on calcification of B. elegans than pCO2. Net calcification was positive even at 1230 μatm (~ 3 times current atmospheric pCO2), although the increase from 410 to 1230 μatm reduced overall calcification by ~ 25-45%, and reduced skeletal density by ~ 35-45%. Higher pCO2 also altered aragonite crystal morphology significantly. We discuss how feeding frequency affects azooxanthellate coral calcification, and how B. elegans may respond to ocean acidification in coastal upwelling waters.

In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites.

PubMed

Lamare, Miles D; Liddy, Michelle; Uthicke, Sven

2016-11-30

Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO 2 and ambient pCO 2 coral reefs in Papua New Guinea. Echinometra embryos/larvae were reared in meshed chambers moored in arrays on either venting reefs or adjacent non-vent reefs. After 24 and 48 h, larval development and morphology were quantified. Compared with controls (mean pH (T) = 7.89-7.92), larvae developing in elevated pCO 2 vent conditions (pH (T) = 7.50-7.72) displayed a significant reduction in size and increased abnormality, with a significant correlation of seawater pH with both larval size and larval asymmetry across all experiments. Reciprocal transplants (embryos from vent adults transplanted to control conditions, and vice versa) were also undertaken to identify if adult acclimatization can translate resilience to offspring (i.e. transgenerational processes). Embryos originating from vent adults were, however, no more tolerant to reduced pH. Sea temperature and chlorophyll-a concentrations (i.e. larval nutrition) did not contribute to difference in larval size, but abnormality was correlated with chlorophyll levels. This study is the first to examine the response of marine larvae to OA scenarios in the natural environment where, importantly, we found that stunted and abnormal development observed in situ are consistent with laboratory observations reported in sea urchins, in both the direction and magnitude of the response. © 2016 The Author(s).

In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites

PubMed Central

Liddy, Michelle; Uthicke, Sven

2016-01-01

Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO2 and ambient pCO2 coral reefs in Papua New Guinea. Echinometra embryos/larvae were reared in meshed chambers moored in arrays on either venting reefs or adjacent non-vent reefs. After 24 and 48 h, larval development and morphology were quantified. Compared with controls (mean pH(T) = 7.89–7.92), larvae developing in elevated pCO2 vent conditions (pH(T) = 7.50–7.72) displayed a significant reduction in size and increased abnormality, with a significant correlation of seawater pH with both larval size and larval asymmetry across all experiments. Reciprocal transplants (embryos from vent adults transplanted to control conditions, and vice versa) were also undertaken to identify if adult acclimatization can translate resilience to offspring (i.e. transgenerational processes). Embryos originating from vent adults were, however, no more tolerant to reduced pH. Sea temperature and chlorophyll-a concentrations (i.e. larval nutrition) did not contribute to difference in larval size, but abnormality was correlated with chlorophyll levels. This study is the first to examine the response of marine larvae to OA scenarios in the natural environment where, importantly, we found that stunted and abnormal development observed in situ are consistent with laboratory observations reported in sea urchins, in both the direction and magnitude of the response. PMID:27903867

Impacts of the phenylpyrazole insecticide fipronil on larval fish: time-series gene transcription responses in fathead minnow (Pimephales promelas) following short-term exposure.

PubMed

Beggel, Sebastian; Werner, Inge; Connon, Richard E; Geist, Juergen P

2012-06-01

The utilization of molecular endpoints in ecotoxicology can provide rapid and valuable information on immediate organismal responses to chemical stressors and is increasingly used for mechanistic interpretation of effects at higher levels of biological organization. This study contributes knowledge on the sublethal effects of a commonly used insecticide, the phenylpyrazole fipronil, on larval fathead minnow (Pimephales promelas), utilizing a quantitative transcriptomic approach. Immediately after 24h of exposure to fipronil concentrations of ≥31 μg.L(-1), highly significant changes in gene transcription were observed for aspartoacylase, metallothionein, glucocorticoid receptor, cytochrome P450 3A126 and vitellogenin. Different mechanisms of toxicity were apparent over the course of the experiment, with short-term responses indicating neurotoxic effects. After 6 days of recovery, endocrine effects were observed with vitellogenin being up-regulated 90-fold at 61 μg.L(-1) fipronil. Principal component analysis demonstrated a significant increase in gene transcription changes over time and during the recovery period. In conclusion, multiple mechanisms of action were observed in response to fipronil exposure, and unknown delayed effects would have been missed if transcriptomic responses had only been measured at a single time-point. These challenges can be overcome by the inclusion of multiple endpoints and delayed effects in experimental designs. Copyright © 2012 Elsevier B.V. All rights reserved.

GigaTON: an extensive publicly searchable database providing a new reference transcriptome in the pacific oyster Crassostrea gigas.

PubMed

Riviere, Guillaume; Klopp, Christophe; Ibouniyamine, Nabihoudine; Huvet, Arnaud; Boudry, Pierre; Favrel, Pascal

2015-12-02

The Pacific oyster, Crassostrea gigas, is one of the most important aquaculture shellfish resources worldwide. Important efforts have been undertaken towards a better knowledge of its genome and transcriptome, which makes now C. gigas becoming a model organism among lophotrochozoans, the under-described sister clade of ecdysozoans within protostomes. These massive sequencing efforts offer the opportunity to assemble gene expression data and make such resource accessible and exploitable for the scientific community. Therefore, we undertook this assembly into an up-to-date publicly available transcriptome database: the GigaTON (Gigas TranscriptOme pipeliNe) database. We assembled 2204 million sequences obtained from 114 publicly available RNA-seq libraries that were realized using all embryo-larval development stages, adult organs, different environmental stressors including heavy metals, temperature, salinity and exposure to air, which were mostly performed as part of the Crassostrea gigas genome project. This data was analyzed in silico and resulted into 56621 newly assembled contigs that were deposited into a publicly available database, the GigaTON database. This database also provides powerful and user-friendly request tools to browse and retrieve information about annotation, expression level, UTRs, splice and polymorphism, and gene ontology associated to all the contigs into each, and between all libraries. The GigaTON database provides a convenient, potent and versatile interface to browse, retrieve, confront and compare massive transcriptomic information in an extensive range of conditions, tissues and developmental stages in Crassostrea gigas. To our knowledge, the GigaTON database constitutes the most extensive transcriptomic database to date in marine invertebrates, thereby a new reference transcriptome in the oyster, a highly valuable resource to physiologists and evolutionary biologists.

Assessing Oil Spill Impacts to Cold-Water Corals of the Deep Gulf of Mexico

NASA Astrophysics Data System (ADS)

DeLeo, D. M.; Lengyel, S. D.; Cordes, E. E.

2016-02-01

The Deepwater Horizon (DWH) disaster and subsequent cleanup efforts resulted in the release of an unprecedented amount of oil and chemical dispersants in the deep waters of the Gulf of Mexico (GoM). Over the years, numerous detrimental effects have been documented including impacts to cold-water coral ecosystems. Assessing and quantifying these effects is crucial to understanding the long-term consequences to affected coral populations as well as their resilience. We conducted live exposure experiments to investigate the toxicity of oil and dispersants on two deep-sea corals, Callogorgia delta and Paramuricea type B3. For both species, the treatments containing dispersants had a more pronounced effect than oil treatments alone. In addition, RNA from unexposed and DWH spill-impacted Paramuricea biscaya was extracted and sequenced using Illumina technology. A de novo reference transcriptome was produced and used to explore stress-induced variations in gene expression. Current findings show overexpression of genes coding for Cytochrome p450 (CYP1A1), Tumor necrosis factor receptor-associated factors (TRAFs), Peroxidasin and additional genes involved in innate immunity and apoptotic pathways. CYP1A1 is involved in the metabolism of xenobiotics and has been previously used as a diagnostic tool for aquatic pollution. TRAFs are responsible for regulating pathways involved in immune and inflammatory responses and were likewise overexpressed in thermally stressed shallow-water corals. Ribosomal proteins were also significantly underexpressed. These genes among others found in our expression data serve as useful biomarker candidates for assessing and monitoring future spill impacts as resource extraction continues in the deep waters of the GoM. Our results also provide insights into the responses of deep-sea corals to toxin exposure, implications of applying dispersants to oil spills and a novel reference assembly for a relatively under-studied group of cold-water corals.

Impacts of food availability and pCO2 on planulation, juvenile survival, and calcification of the azooxanthellate scleractinian coral Balanophyllia elegans

NASA Astrophysics Data System (ADS)

Crook, E. D.; Cooper, H.; Potts, D. C.; Lambert, T.; Paytan, A.

2013-11-01

Ocean acidification, the assimilation of atmospheric CO2 by the oceans that decreases the pH and CaCO3 saturation state (Ω) of seawater, is projected to have severe adverse consequences for calcifying organisms. While strong evidence suggests calcification by tropical reef-building corals containing algal symbionts (zooxanthellae) will decline over the next century, likely responses of azooxanthellate corals to ocean acidification are less well understood. Because azooxanthellate corals do not obtain photosynthetic energy from symbionts, they provide a system for studying the direct effects of acidification on energy available for calcification. The solitary azooxanthellate orange cup coral Balanophyllia elegans often lives in low-pH, upwelled waters along the California coast. In an 8-month factorial experiment, we measured the effects of three pCO2 treatments (410, 770, and 1220 μatm) and two feeding frequencies (3-day and 21-day intervals) on "planulation" (larval release) by adult B. elegans, and on the survival, skeletal growth, and calcification of newly settled juveniles. Planulation rates were affected by food level but not pCO2. Juvenile mortality was highest under high pCO2 (1220 μatm) and low food (21-day intervals). Feeding rate had a greater impact on calcification of B. elegans than pCO2. While net calcification was positive even at 1220 μatm (~3 times current atmospheric pCO2), overall calcification declined by ~25-45%, and skeletal density declined by ~35-45% as pCO2 increased from 410 to 1220 μatm. Aragonite crystal morphology changed at high pCO2, becoming significantly shorter but not wider at 1220 μatm. We conclude that food abundance is critical for azooxanthellate coral calcification, and that B. elegans may be partially protected from adverse consequences of ocean acidification in habitats with abundant heterotrophic food.

Rearing Water Treatment Induces Microbial Selection Influencing the Microbiota and Pathogen Associated Transcripts of Cod (Gadus morhua) Larvae.

PubMed

Vestrum, Ragnhild I; Attramadal, Kari J K; Winge, Per; Li, Keshuai; Olsen, Yngvar; Bones, Atle M; Vadstein, Olav; Bakke, Ingrid

2018-01-01

We have previously shown that K-selection and microbial stability in the rearing water increases survival and growth of Atlantic cod ( Gadus morhua ) larvae, and that recirculating aquaculture systems (RAS) are compatible with this. Here, we have assessed how water treatment influenced the larval microbiota and host responses at the gene expression level. Cod larvae were reared with two different rearing water systems: a RAS and a flow-through system (FTS). The water microbiota was examined using a 16S rDNA PCR/DGGE strategy. RNA extracted from larvae at 8, 13, and 17 days post hatching was used for microbiota and microarray gene expression analysis. Bacterial cDNA was synthesized and used for 16S rRNA amplicon 454 pyrosequencing of larval microbiota. Both water and larval microbiota differed significantly between the systems, and the larval microbiota appeared to become more dissimilar between systems with time. In total 4 phyla were identified for all larvae: Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. The most profound difference in larval microbiota was a high abundance of Arcobacter (Epsilonproteobacteria) in FTS larvae (34 ± 9% of total reads). Arcobacter includes several species that are known pathogens for humans and animals. Cod larval transcriptome responses were investigated using an oligonucleotide gene expression microarray covering approximately 24,000 genes. Interestingly, FTS larvae transcriptional profiles revealed an overrepresentation of upregulated transcripts associated with responses to pathogens and infections, such as c1ql3-like , pglyrp-2-like and zg16, compared to RAS larvae. In conclusion, distinct water treatment systems induced differences in the larval microbiota. FTS larvae showed up-regulation of transcripts associated with responses to microbial stress. These results are consistent with the hypothesis that RAS promotes K-selection and microbial stability by maintaining a microbial load close to the carrying capacity of the system, and ensuring long retention times for both bacteria and water in the system.

Rearing Water Treatment Induces Microbial Selection Influencing the Microbiota and Pathogen Associated Transcripts of Cod (Gadus morhua) Larvae

PubMed Central

Vestrum, Ragnhild I.; Attramadal, Kari J. K.; Winge, Per; Li, Keshuai; Olsen, Yngvar; Bones, Atle M.; Vadstein, Olav; Bakke, Ingrid

2018-01-01

We have previously shown that K-selection and microbial stability in the rearing water increases survival and growth of Atlantic cod (Gadus morhua) larvae, and that recirculating aquaculture systems (RAS) are compatible with this. Here, we have assessed how water treatment influenced the larval microbiota and host responses at the gene expression level. Cod larvae were reared with two different rearing water systems: a RAS and a flow-through system (FTS). The water microbiota was examined using a 16S rDNA PCR/DGGE strategy. RNA extracted from larvae at 8, 13, and 17 days post hatching was used for microbiota and microarray gene expression analysis. Bacterial cDNA was synthesized and used for 16S rRNA amplicon 454 pyrosequencing of larval microbiota. Both water and larval microbiota differed significantly between the systems, and the larval microbiota appeared to become more dissimilar between systems with time. In total 4 phyla were identified for all larvae: Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. The most profound difference in larval microbiota was a high abundance of Arcobacter (Epsilonproteobacteria) in FTS larvae (34 ± 9% of total reads). Arcobacter includes several species that are known pathogens for humans and animals. Cod larval transcriptome responses were investigated using an oligonucleotide gene expression microarray covering approximately 24,000 genes. Interestingly, FTS larvae transcriptional profiles revealed an overrepresentation of upregulated transcripts associated with responses to pathogens and infections, such as c1ql3-like, pglyrp-2-like and zg16, compared to RAS larvae. In conclusion, distinct water treatment systems induced differences in the larval microbiota. FTS larvae showed up-regulation of transcripts associated with responses to microbial stress. These results are consistent with the hypothesis that RAS promotes K-selection and microbial stability by maintaining a microbial load close to the carrying capacity of the system, and ensuring long retention times for both bacteria and water in the system. PMID:29765364

Transcriptomic Changes in Coral Holobionts Provide Insights into Physiological Challenges of Future Climate and Ocean Change.

PubMed

Kaniewska, Paulina; Chan, Chon-Kit Kenneth; Kline, David; Ling, Edmund Yew Siang; Rosic, Nedeljka; Edwards, David; Hoegh-Guldberg, Ove; Dove, Sophie

2015-01-01

Tropical reef-building coral stress levels will intensify with the predicted rising atmospheric CO2 resulting in ocean temperature and acidification increase. Most studies to date have focused on the destabilization of coral-dinoflagellate symbioses due to warming oceans, or declining calcification due to ocean acidification. In our study, pH and temperature conditions consistent with the end-of-century scenarios of the Intergovernmental Panel on Climate Change (IPCC) caused major changes in photosynthesis and respiration, in addition to decreased calcification rates in the coral Acropora millepora. Population density of symbiotic dinoflagellates (Symbiodinium) under high levels of ocean acidification and temperature (Representative Concentration Pathway, RCP8.5) decreased to half of that found under present day conditions, with photosynthetic and respiratory rates also being reduced by 40%. These physiological changes were accompanied by evidence for gene regulation of calcium and bicarbonate transporters along with components of the organic matrix. Metatranscriptomic RNA-Seq data analyses showed an overall down regulation of metabolic transcripts, and an increased abundance of transcripts involved in circadian clock control, controlling the damage of oxidative stress, calcium signaling/homeostasis, cytoskeletal interactions, transcription regulation, DNA repair, Wnt signaling and apoptosis/immunity/ toxins. We suggest that increased maintenance costs under ocean acidification and warming, and diversion of cellular ATP to pH homeostasis, oxidative stress response, UPR and DNA repair, along with metabolic suppression, may underpin why Acroporid species tend not to thrive under future environmental stress. Our study highlights the potential increased energy demand when the coral holobiont is exposed to high levels of ocean warming and acidification.

Transcriptomic Changes in Coral Holobionts Provide Insights into Physiological Challenges of Future Climate and Ocean Change

PubMed Central

Kaniewska, Paulina; Chan, Chon-Kit Kenneth; Kline, David; Ling, Edmund Yew Siang; Rosic, Nedeljka; Edwards, David; Hoegh-Guldberg, Ove; Dove, Sophie

2015-01-01

Tropical reef-building coral stress levels will intensify with the predicted rising atmospheric CO2 resulting in ocean temperature and acidification increase. Most studies to date have focused on the destabilization of coral-dinoflagellate symbioses due to warming oceans, or declining calcification due to ocean acidification. In our study, pH and temperature conditions consistent with the end-of-century scenarios of the Intergovernmental Panel on Climate Change (IPCC) caused major changes in photosynthesis and respiration, in addition to decreased calcification rates in the coral Acropora millepora. Population density of symbiotic dinoflagellates (Symbiodinium) under high levels of ocean acidification and temperature (Representative Concentration Pathway, RCP8.5) decreased to half of that found under present day conditions, with photosynthetic and respiratory rates also being reduced by 40%. These physiological changes were accompanied by evidence for gene regulation of calcium and bicarbonate transporters along with components of the organic matrix. Metatranscriptomic RNA-Seq data analyses showed an overall down regulation of metabolic transcripts, and an increased abundance of transcripts involved in circadian clock control, controlling the damage of oxidative stress, calcium signaling/homeostasis, cytoskeletal interactions, transcription regulation, DNA repair, Wnt signaling and apoptosis/immunity/ toxins. We suggest that increased maintenance costs under ocean acidification and warming, and diversion of cellular ATP to pH homeostasis, oxidative stress response, UPR and DNA repair, along with metabolic suppression, may underpin why Acroporid species tend not to thrive under future environmental stress. Our study highlights the potential increased energy demand when the coral holobiont is exposed to high levels of ocean warming and acidification. PMID:26510159

Ocean acidification reduces induction of coral settlement by crustose coralline algae.

PubMed

Webster, Nicole S; Uthicke, Sven; Botté, Emanuelle S; Flores, Florita; Negri, Andrew P

2013-01-01

Crustose coralline algae (CCA) are a critical component of coral reefs as they accrete carbonate for reef structure and act as settlement substrata for many invertebrates including corals. CCA host a diversity of microorganisms that can also play a role in coral settlement and metamorphosis processes. Although the sensitivity of CCA to ocean acidification (OA) is well established, the response of their associated microbial communities to reduced pH and increased CO2 was previously not known. Here we investigate the sensitivity of CCA-associated microbial biofilms to OA and determine whether or not OA adversely affects the ability of CCA to induce coral larval metamorphosis. We experimentally exposed the CCA Hydrolithon onkodes to four pH/pCO2 conditions consistent with current IPCC predictions for the next few centuries (pH: 8.1, 7.9, 7.7, 7.5, pCO2 : 464, 822, 1187, 1638 μatm). Settlement and metamorphosis of coral larvae was reduced on CCA pre-exposed to pH 7.7 (pCO2  = 1187 μatm) and below over a 6-week period. Additional experiments demonstrated that low pH treatments did not directly affect the ability of larvae to settle, but instead most likely altered the biochemistry of the CCA or its microbial associates. Detailed microbial community analysis of the CCA revealed diverse bacterial assemblages that altered significantly between pH 8.1 (pCO2  = 464 μatm) and pH 7.9 (pCO2  = 822 μatm) with this trend continuing at lower pH/higher pCO2 treatments. The shift in microbial community composition primarily comprised changes in the abundance of the dominant microbes between the different pH treatments and the appearance of new (but rare) microbes at pH 7.5. Microbial shifts and the concomitant reduced ability of CCA to induce coral settlement under OA conditions projected to occur by 2100 is a significant concern for the development, maintenance and recovery of reefs globally. © 2012 Blackwell Publishing Ltd.

The reproductive biology and early life ecology of a common Caribbean brain coral, Diploria labyrinthiformis (Scleractinia: Faviinae)

NASA Astrophysics Data System (ADS)

Chamberland, Valérie F.; Snowden, Skylar; Marhaver, Kristen L.; Petersen, Dirk; Vermeij, Mark J. A.

2017-03-01

Despite the fact that most of the severe demographic bottlenecks in coral populations occur during their earliest life stages, information on the reproductive biology and early life history traits of many coral species is limited and often inferred from adult traits only. This study reports on several atypical aspects of the reproductive biology and early life ecology of the grooved brain coral, Diploria labyrinthiformis (Linnaeus, 1758), a conspicuous reef-building species on Caribbean reefs. The timing of gamete release of D. labyrinthiformis was monitored in Curaçao over eight consecutive months, and embryogenesis, planulae behavior, and settlement rates were observed and quantified. We further studied growth and symbiont acquisition in juvenile D. labyrinthiformis for 3.5 yr and compared settler survival under ambient and nutrient-enriched conditions in situ. Notably, D. labyrinthiformis reproduced during daylight hours in six consecutive monthly spawning events between May and September 2013, with a peak in June. This is the largest number of reproductive events per year ever observed in a broadcast-spawning Caribbean coral species. In settlement experiments, D. labyrinthiformis planulae swam to the bottom of culture containers 13 h after spawning and rapidly settled when provided with settlement cues (42% within 14 h). After 5 months, the survival and growth rates of settled juveniles were 3.7 and 1.9 times higher, respectively, for settlers that acquired zooxanthellae within 1 month after settlement, compared to those that acquired symbionts later on. Nutrient enrichment increased settler survival fourfold, but only for settlers that had acquired symbionts within 1 month after settlement. With at least six reproductive events per year, a short planktonic larval phase, high settlement rates, and a positive response to nutrient enrichment, the broadcast-spawning species D. labyrinthiformis displays a range of reproductive and early life-history traits that are more often associated with brooding coral species, illustrating that classical divisions of coral species by reproductive mode alone do not always reflect the true biology and ecology of their earliest life stages.

Global ocean conveyor lowers extinction risk in the deep sea

USGS Publications Warehouse

Henry, Lea-Anne; Frank, Norbert; Hebbeln, Dierk; Weinberg, Claudia; Robinson, Laura; van de Flierdt, Tina; Dahl, Mikael; Douarin, Melanie; Morrison, Cheryl L.; Correa, Matthias Lopez; Rogers, Alex D.; Ruckelshausen, Mario; Roberts, J. Murray

2014-01-01

General paradigms of species extinction risk are urgently needed as global habitat loss and rapid climate change threaten Earth with what could be its sixth mass extinction. Using the stony coral Lophelia pertusa as a model organism with the potential for wide larval dispersal, we investigated how the global ocean conveyor drove an unprecedented post-glacial range expansion in Earth׳s largest biome, the deep sea. We compiled a unique ocean-scale dataset of published radiocarbon and uranium-series dates of fossil corals, the sedimentary protactinium–thorium record of Atlantic meridional overturning circulation (AMOC) strength, authigenic neodymium and lead isotopic ratios of circulation pathways, and coral biogeography, and integrated new Bayesian estimates of historic gene flow. Our compilation shows how the export of Southern Ocean and Mediterranean waters after the Younger Dryas 11.6 kyr ago simultaneously triggered two dispersal events in the western and eastern Atlantic respectively. Each pathway injected larvae from refugia into ocean currents powered by a re-invigorated AMOC that led to the fastest postglacial range expansion ever recorded, covering 7500 km in under 400 years. In addition to its role in modulating global climate, our study illuminates how the ocean conveyor creates broad geographic ranges that lower extinction risk in the deep sea.

Growth rates of Porites astreoides and Orbicella franksi in mesophotic habitats surrounding St. Thomas, US Virgin Islands

NASA Astrophysics Data System (ADS)

Groves, Sarah H.; Holstein, Daniel M.; Enochs, Ian C.; Kolodzeij, Graham; Manzello, Derek P.; Brandt, Marilyn E.; Smith, Tyler B.

2018-06-01

Mesophotic coral ecosystems (MCEs) are deep (> 30 m), light-dependent communities that are abundant in many parts of the global ocean. MCEs are potentially connected to shallow reefs via larval exchange and may act as refuges for reef organisms. However, MCE community level recovery after disturbance, and thus, community resilience, are poorly understood components of their capacity as refuges. To assess the potential for disturbance and growth to drive community structure on MCEs with differential biophysical conditions and coral communities, we collected colonies of Orbicella franksi and Porites astreoides and used computerized tomography to quantify calcification. The divergence of coral growth rates in MCEs with different environmental conditions may be species specific; habitat-forming O. franksi have slow and consistent growth rates of 0.2 cm yr-1 below 30 m, regardless of mesophotic habitat, compared to 1.0 cm yr-1 in shallow-water habitats. Slow skeletal growth rates in MCEs suggest that rates of recovery from disturbance will likely also be slow. Localized buffering of MCEs from the stressors affecting shallow reefs is therefore crucial to the long-term capacity of these sites to serve as refugia, given that skeletal extension and recovery from disturbance in MCEs will be significantly slower than on shallow reefs.

Global ocean conveyor lowers extinction risk in the deep sea

NASA Astrophysics Data System (ADS)

Henry, Lea-Anne; Frank, Norbert; Hebbeln, Dierk; Wienberg, Claudia; Robinson, Laura; van de Flierdt, Tina; Dahl, Mikael; Douarin, Mélanie; Morrison, Cheryl L.; López Correa, Matthias; Rogers, Alex D.; Ruckelshausen, Mario; Roberts, J. Murray

2014-06-01

General paradigms of species extinction risk are urgently needed as global habitat loss and rapid climate change threaten Earth with what could be its sixth mass extinction. Using the stony coral Lophelia pertusa as a model organism with the potential for wide larval dispersal, we investigated how the global ocean conveyor drove an unprecedented post-glacial range expansion in Earth's largest biome, the deep sea. We compiled a unique ocean-scale dataset of published radiocarbon and uranium-series dates of fossil corals, the sedimentary protactinium-thorium record of Atlantic meridional overturning circulation (AMOC) strength, authigenic neodymium and lead isotopic ratios of circulation pathways, and coral biogeography, and integrated new Bayesian estimates of historic gene flow. Our compilation shows how the export of Southern Ocean and Mediterranean waters after the Younger Dryas 11.6 kyr ago simultaneously triggered two dispersal events in the western and eastern Atlantic respectively. Each pathway injected larvae from refugia into ocean currents powered by a re-invigorated AMOC that led to the fastest postglacial range expansion ever recorded, covering 7500 km in under 400 years. In addition to its role in modulating global climate, our study illuminates how the ocean conveyor creates broad geographic ranges that lower extinction risk in the deep sea.

Dispersal capacity and genetic relatedness in Acropora cervicornis on the Florida Reef Tract

NASA Astrophysics Data System (ADS)

Drury, Crawford; Paris, Claire B.; Kourafalou, Vassiliki H.; Lirman, Diego

2018-06-01

Sexual reproduction in scleractinian corals is a critical component of species recovery, fostering population connectivity and enhancing genetic diveristy. The relative contribution of sexual reproduction to both connectivity and diversity in Acropora cervicornis may be variable due to this species' capacity to reproduce effectively by fragmentation. Using a biophysical model and genomic data in this threatened species, we construct potential connectivity pathways on the Florida Reef Tract (FRT) and compare them to inferred migration rates derived from next-generation sequencing, using a link and node-based approach. Larval connectivity on the FRT can be divided into two zones: the northern region, where most transport is unidirectional to the north with the Florida Current, and the southern region that is more dynamic and exhibits complex spatial patterns. These biophysical linkages are poorly correlated with genetic connectivity patterns, which resolve many reciprocal connections and suggest a less sparse network. These results are difficult to reconcile with genetic data which indicate that individual reefs are diverse, suggesting important contributions of sexual reproduction and recruitment. Larval connectivity models highlight potential resources for recovery, such as areas with high larval export like the Lower Keys, or areas that are well connected to most other regions on the FRT, such as the Dry Tortugas.

The Neuronal Calcium Sensor Protein Acrocalcin: A Potential Target of Calmodulin Regulation during Development in the Coral Acropora millepora

PubMed Central

Reyes-Bermudez, Alejandro; Miller, David J.; Sprungala, Susanne

2012-01-01

To understand the calcium-mediated signalling pathways underlying settlement and metamorphosis in the Scleractinian coral Acropora millepora, a predicted protein set derived from larval cDNAs was scanned for the presence of EF-hand domains (Pfam Id: PF00036). This approach led to the identification of a canonical calmodulin (AmCaM) protein and an uncharacterised member of the Neuronal Calcium Sensor (NCS) family of proteins known here as Acrocalcin (AmAC). While AmCaM transcripts were present throughout development, AmAC transcripts were not detected prior to gastrulation, after which relatively constant mRNA levels were detected until metamorphosis and settlement. The AmAC protein contains an internal CaM-binding site and was shown to interact in vitro with AmCaM. These results are consistent with the idea that AmAC is a target of AmCaM in vivo, suggesting that this interaction may regulate calcium-dependent processes during the development of Acropora millepora. PMID:23284743

Tropical CO2 seeps reveal the impact of ocean acidification on coral reef invertebrate recruitment.

PubMed

Allen, Ro; Foggo, Andrew; Fabricius, Katharina; Balistreri, Annalisa; Hall-Spencer, Jason M

2017-11-30

Rising atmospheric CO 2 concentrations are causing ocean acidification by reducing seawater pH and carbonate saturation levels. Laboratory studies have demonstrated that many larval and juvenile marine invertebrates are vulnerable to these changes in surface ocean chemistry, but challenges remain in predicting effects at community and ecosystem levels. We investigated the effect of ocean acidification on invertebrate recruitment at two coral reef CO 2 seeps in Papua New Guinea. Invertebrate communities differed significantly between 'reference' (median pH7.97, 8.00), 'high CO 2 ' (median pH7.77, 7.79), and 'extreme CO 2 ' (median pH7.32, 7.68) conditions at each reef. There were also significant reductions in calcifying taxa, copepods and amphipods as CO 2 levels increased. The observed shifts in recruitment were comparable to those previously described in the Mediterranean, revealing an ecological mechanism by which shallow coastal systems are affected by near-future levels of ocean acidification. Copyright © 2016 Elsevier Ltd. All rights reserved.

Transcriptomic basis for an antiserum against Micrurus corallinus (coral snake) venom.

PubMed

Leão, Luciana I; Ho, Paulo L; Junqueira-de-Azevedo, Inacio de L M

2009-03-16

Micrurus corallinus (coral snake) is a tropical forest snake belonging to the family Elapidae. Its venom shows a high neurotoxicity associated with pre- and post-synaptic toxins, causing diaphragm paralysis, which may result in death. In spite of a relatively small incidence of accidents, serum therapy is crucial for those bitten. However, the adequate production of antiserum is hampered by the difficulty in obtaining sufficient amounts of venom from a small snake with demanding breeding conditions. In order to elucidate the molecular basis of this venom and to uncover possible immunogens for an antiserum, we generated expressed sequences tags (ESTs) from its venom glands and analyzed the transcriptomic profile. In addition, their immunogenicity was tested using DNA immunization. A total of 1438 ESTs were generated and grouped into 611 clusters. Toxin transcripts represented 46% of the total ESTs. The two main toxin classes consisted of three-finger toxins (3FTx) (24%) and phospholipases A(2) (PLA(2)s) (15%). However, 8 other classes of toxins were present, including C-type lectins, natriuretic peptide precursors and even high-molecular mass components such as metalloproteases and L-amino acid oxidases. Each class included an assortment of isoforms, some showing evidence of alternative splicing and domain deletions. Five antigenic candidates were selected (four 3FTx and one PLA(2)) and used for a preliminary study of DNA immunization. The immunological response showed that the sera from the immunized animals were able to recognize the recombinant antigens. Besides an improvement in our knowledge of the composition of coral snake venoms, which are very poorly known when compared to Old World elapids, the expression profile suggests abundant and diversified components that may be used in future antiserum formulation. As recombinant production of venom antigens frequently fails due to complex disulfide arrangements, DNA immunization may be a viable alternative. In fact, the selected candidates provided an initial evidence of the feasibility of this approach, which is less costly and not dependent on the availability of the venom.

Transcriptome Analysis of Barbarea vulgaris Infested with Diamondback Moth (Plutella xylostella) Larvae

PubMed Central

Shen, Di; Wang, Haiping; Wu, Qingjun; Lu, Peng; Qiu, Yang; Song, Jiangping; Zhang, Youjun; Li, Xixiang

2013-01-01

Background The diamondback moth (DBM, Plutella xylostella) is a crucifer-specific pest that causes significant crop losses worldwide. Barbarea vulgaris (Brassicaceae) can resist DBM and other herbivorous insects by producing feeding-deterrent triterpenoid saponins. Plant breeders have long aimed to transfer this insect resistance to other crops. However, a lack of knowledge on the biosynthetic pathways and regulatory networks of these insecticidal saponins has hindered their practical application. A pyrosequencing-based transcriptome analysis of B. vulgaris during DBM larval feeding was performed to identify genes and gene networks responsible for saponin biosynthesis and its regulation at the genome level. Principal Findings Approximately 1.22, 1.19, 1.16, 1.23, 1.16, 1.20, and 2.39 giga base pairs of clean nucleotides were generated from B. vulgaris transcriptomes sampled 1, 4, 8, 12, 24, and 48 h after onset of P. xylostella feeding and from non-inoculated controls, respectively. De novo assembly using all data of the seven transcriptomes generated 39,531 unigenes. A total of 37,780 (95.57%) unigenes were annotated, 14,399 of which were assigned to one or more gene ontology terms and 19,620 of which were assigned to 126 known pathways. Expression profiles revealed 2,016–4,685 up-regulated and 557–5188 down-regulated transcripts. Secondary metabolic pathways, such as those of terpenoids, glucosinolates, and phenylpropanoids, and its related regulators were elevated. Candidate genes for the triterpene saponin pathway were found in the transcriptome. Orthological analysis of the transcriptome with four other crucifer transcriptomes identified 592 B. vulgaris-specific gene families with a P-value cutoff of 1e−5. Conclusion This study presents the first comprehensive transcriptome analysis of B. vulgaris subjected to a series of DBM feedings. The biosynthetic and regulatory pathways of triterpenoid saponins and other DBM deterrent metabolites in this plant were classified. The results of this study will provide useful data for future investigations on pest-resistance phytochemistry and plant breeding. PMID:23696897

Put a tiger in your tank: the polyclad flatworm Maritigrella crozieri as a proposed model for evo-devo.

PubMed

Lapraz, François; Rawlinson, Kate A; Girstmair, Johannes; Tomiczek, Bartłomiej; Berger, Jürgen; Jékely, Gáspár; Telford, Maximilian J; Egger, Bernhard

2013-10-09

Polyclad flatworms are an early branching clade within the rhabditophoran Platyhelminthes. They provide an interesting system with which to explore the evolution of development within Platyhelminthes and amongst Spiralia (Lophotrochozoa). Unlike most other flatworms, polyclads undergo spiral cleavage (similar to that seen in some other spiralian taxa), they are the only free-living flatworms where development via a larval stage occurs, and they are the only flatworms in which embryos can be reared outside of their protective egg case, enabling embryonic manipulations. Past work has focused on comparing early cleavage patterns and larval anatomy between polyclads and other spiralians. We have selected Maritigrella crozieri, the tiger flatworm, as a suitable polyclad species for developmental studies, because it is abundant and large in size compared to other species. These characteristics have facilitated the generation of a transcriptome from embryonic and larval material and are enabling us to develop methods for gene expression analysis and immunofluorescence techniques. Here we give an overview of M. crozieri and its development, we highlight the advantages and current limitations of this animal as a potential evo-devo model and discuss current lines of research.

Put a tiger in your tank: the polyclad flatworm Maritigrella crozieri as a proposed model for evo-devo

PubMed Central

2013-01-01

Polyclad flatworms are an early branching clade within the rhabditophoran Platyhelminthes. They provide an interesting system with which to explore the evolution of development within Platyhelminthes and amongst Spiralia (Lophotrochozoa). Unlike most other flatworms, polyclads undergo spiral cleavage (similar to that seen in some other spiralian taxa), they are the only free-living flatworms where development via a larval stage occurs, and they are the only flatworms in which embryos can be reared outside of their protective egg case, enabling embryonic manipulations. Past work has focused on comparing early cleavage patterns and larval anatomy between polyclads and other spiralians. We have selected Maritigrella crozieri, the tiger flatworm, as a suitable polyclad species for developmental studies, because it is abundant and large in size compared to other species. These characteristics have facilitated the generation of a transcriptome from embryonic and larval material and are enabling us to develop methods for gene expression analysis and immunofluorescence techniques. Here we give an overview of M. crozieri and its development, we highlight the advantages and current limitations of this animal as a potential evo-devo model and discuss current lines of research. PMID:24107307

Prolidase is a critical enzyme for complete gliadin digestion in Tenebrio molitor larvae.

PubMed

Tereshchenkova, Valeriia F; Goptar, Irina A; Zhuzhikov, Dmitry P; Belozersky, Mikhail A; Dunaevsky, Yakov E; Oppert, Brenda; Filippova, Irina Yu; Elpidina, Elena N

2017-08-01

Prolidase is a proline-specific metallopeptidase that cleaves imidodipeptides with C-terminal Pro residue. Prolidase was purified and characterized from the Tenebrio molitor larval midgut. The enzyme was localized in the soluble fraction of posterior midgut tissues, corresponding to a predicted cytoplasmic localization of prolidase according to the structure of the mRNA transcript. Expression of genes encoding prolidase and the major digestive proline-specific peptidase (PSP)-dipeptidyl peptidase 4-were similar. The pH optimum of T. molitor prolidase was 7.5, and the enzyme was inhibited by Z-Pro, indicating that it belongs to type I prolidases. In mammals, prolidase is particularly important in the catabolism of a proline-rich protein-collagen. We propose that T. molitor larval prolidase is a critical enzyme for the final stages of digestion of dietary proline-rich gliadins, providing hydrolysis of imidodipeptides in the cytoplasm of midgut epithelial cells. We propose that the products of hydrolysis are absorbed from the luminal contents by peptide transporters, which we have annotated in the T. molitor larval gut transcriptome. The origin of prolidase substrates in the insect midgut is discussed in the context of overall success of grain feeding insects. © 2017 Wiley Periodicals, Inc.

Coral reef fishes exhibit beneficial phenotypes inside marine protected areas

PubMed Central

Carroll, Jessica; Rynerson, Kristen W.; Matthews, Danielle F.; Turingan, Ralph G.

2018-01-01

Human fishing effort is size-selective, preferentially removing the largest individuals from harvested stocks. Intensive, size-specific fishing mortality induces directional shifts in phenotypic frequencies towards the predominance of smaller and earlier-maturing individuals, which are among the primary causes of declining fish biomass. Fish that reproduce at smaller size and younger age produce fewer, smaller, and less viable larvae, severely reducing the reproductive capacity of harvested populations. Marine protected areas (MPAs) are extensively utilized in coral reefs for fisheries management, and are thought to mitigate the impacts of size-selective fishing mortality and supplement fished stocks through larval export. However, empirical evidence of disparities in fitness-relevant phenotypes between MPAs and adjacent fished reefs is necessary to validate this assertion. Here, we compare key life-history traits in three coral-reef fishes (Acanthurus nigrofuscus, Ctenochaetus striatus, and Parupeneus multifasciatus) between MPAs and fished reefs in the Philippines. Results of our analyses support previous hypotheses regarding the impacts of MPAs on phenotypic traits. Asymptotic length (Linf) and growth rates (K) differed between conspecifics in MPAs and fished reefs, with protected populations exhibiting phenotypes that are known to confer higher fecundity. Additionally, populations demonstrated increases in length at 50% maturity (L50) inside MPAs compared to adjacent areas, although age at 50% maturity (A50) did not appear to be impacted by MPA establishment. Shifts toward advantageous phenotypes were most common in the oldest and largest MPAs, but occurred in all of the MPAs examined. These results suggest that MPAs may provide protection against the impacts of size-selective harvest on life-history traits in coral-reef fishes. PMID:29470525

Volcanic ash supports a diverse bacterial community in a marine mesocosm

USGS Publications Warehouse

Verena Witt,; Paul M Ayris,; Damby, David; Corrado Cimarelli,; Ulrich Kueppers,; Donald B Dingwell,; Gert Wörheide,

2017-01-01

Shallow-water coral reef ecosystems, particularly those already impaired by anthropogenic pressures, may be highly sensitive to disturbances from natural catastrophic events, such as volcanic eruptions. Explosive volcanic eruptions expel large quantities of silicate ash particles into the atmosphere, which can disperse across millions of square kilometres and deposit into coral reef ecosystems. Following heavy ash deposition, mass mortality of reef biota is expected, but little is known about the recovery of post-burial reef ecosystems. Reef regeneration depends partly upon the capacity of the ash deposit to be colonised by waterborne bacterial communities and may be influenced to an unknown extent by the physiochemical properties of the ash substrate itself. To determine the potential for volcanic ash to support pioneer bacterial colonisation, we exposed five well-characterised volcanic and coral reef substrates to a marine aquarium under low light conditions for 3 months: volcanic ash, synthetic volcanic glass, carbonate reef sand, calcite sand and quartz sand. Multivariate statistical analysis of Automated Ribosomal Intergenic Spacer Analysis (ARISA) fingerprinting data demonstrates clear segregation of volcanic substrates from the quartz and coral reef substrates over 3 months of bacterial colonisation. Overall bacterial diversity showed shared and substrate-specific bacterial communities; however, the volcanic ash substrate supported the most diverse bacterial community. These data suggest a significant influence of substrate properties (composition, granulometry and colour) on bacterial settlement. Our findings provide first insights into physicochemical controls on pioneer bacterial colonisation of volcanic ash and highlight the potential for volcanic ash deposits to support bacterial diversity in the aftermath of reef burial, on timescales that could permit cascading effects on larval settlement.

Suppression of NF-κB signal pathway by NLRC3-like protein in stony coral Acropora aculeus under heat stress.

PubMed

Zhou, Zhi; Wu, Yibo; Zhang, Chengkai; Li, Can; Chen, Guangmei; Yu, Xiaopeng; Shi, Xiaowei; Xu, Yanlai; Wang, Lingui; Huang, Bo

2017-08-01

Heat stress is the most common factor for coral bleaching, which has increased both in frequency and severity due to global warming. In the present study, the stony coral Acropora aculeus was subjected to acute heat stress and entire transcriptomes were sequenced via the next generation sequencing platform. Four paired-end libraries were constructed and sequenced in two groups, including a control and a heat stress group. A total of 120,319,751 paired-end reads with lengths of 2 × 100 bp were assembled and 55,021 coral-derived genes were obtained. After read mapping and abundance estimation, 9110 differentially expressed genes were obtained in the comparison between the control and heat stress group, including 4465 significantly upregulated and 4645 significantly downregulated genes. Twenty-three GO terms in the Biological Process category were overrepresented for significantly upregulated genes, and divided into six groups according to their relationship. These three groups were related to the NF-κB signal pathway, and the remaining three groups were relevant for pathogen response, immunocyte activation and protein ubiquitination. Forty-three common genes were found in four GO terms, which were directly related to the NF-κB signal pathway. These included 2 NACHT, LRR, PYD domains-containing protein, 5 nucleotide-binding oligomerization domain-containing protein, 29 NLRC3-like protein, 4 NLRC5-like protein, and 3 uncharacterized protein. For significantly downregulated genes, 27 overrepresented GO terms were found in the Biological Process category, which were relevant to protein ubiquitination and ATP metabolism. Our results indicate that heat stress suppressed the immune response level via the NLRC3-like protein, the fine-tuning of protein turnover activity, and ATP metabolism. This might disrupt the balance of coral-zooxanthellae symbiosis and result in the bleaching of the coral A. aculeus. Copyright © 2017 Elsevier Ltd. All rights reserved.

Limited Capacity for Faster Digestion in Larval Coral Reef Fish at an Elevated Temperature

PubMed Central

Clark, Timothy D.

2016-01-01

The prevalence of extreme, short-term temperature spikes in coastal regions during summer months is predicted to increase with ongoing climate change. In tropical systems, these changes are predicted to increase the metabolic demand of coral reef fish larvae while also altering the plankton communities upon which the larvae feed during their pelagic phase. The consequences of these predictions remain speculative in the absence of empirical data on the interactive effects of warm temperatures on the metabolism, postprandial processes and growth responses of coral reef fish larvae. Here, we tested the effect of increased temperature on the metabolism, postprandial performance and fine-scale growth patterns of a coral reef fish (Amphiprion percula) in the latter half of its ~11-d larval phase. First, we measured the length and weight of fed versus fasted larvae (N = 340; mean body mass 4.1±0.05 mg) across fine temporal scales at a typical current summer temperature (28.5°C) and a temperature that is likely be encountered during warm summer periods later this century (31.5°C). Second, we measured routine metabolic rate (Mo2 routine) and the energetics of the postprandial processes (i.e., digestion, absorption and assimilation of a meal; termed specific dynamic action (SDA)) at both temperatures. Larvae fed voraciously when provided with food for a 12-hour period and displayed a temperature-independent increase in mass of 40.1% (28.5°C) and 42.6% (31.5°C), which was largely associated with the mass of prey in the gut. A subsequent 12-h fasting period revealed that the larvae had grown 21.2±4.8% (28.5°C) and 22.8±8.8% (31.5°C) in mass and 10.3±2.0% (28.5°C) and 7.8±2.6% (31.5°C) in length compared with pre-feeding values (no significant temperature effect). Mo2 routine was 55±16% higher at 31.5°C and peak Mo2 during the postprandial period was 28±11% higher at 31.5°C, yet elevated temperature had no significant effect on SDA (0.51±0.06 J at 28.5°C vs. 0.53±0.07 J at 31.5°C), SDA duration (6.0±0.6 h vs. 6.5±0.5 h), or the percent of total meal energy used for SDA (SDA coefficient: 10.1±1.3% vs. 13.0±1.7%). Our findings of higher Mo2 routine but similar SDA coefficient at high temperature provide the first empirical evidence that coral reef fish larvae may have to secure more food to attain similar growth rates during warm summer periods, and perhaps with chronically warmer conditions associated with climate change. PMID:27191721

Limited Capacity for Faster Digestion in Larval Coral Reef Fish at an Elevated Temperature.

PubMed

McLeod, Ian M; Clark, Timothy D

2016-01-01

The prevalence of extreme, short-term temperature spikes in coastal regions during summer months is predicted to increase with ongoing climate change. In tropical systems, these changes are predicted to increase the metabolic demand of coral reef fish larvae while also altering the plankton communities upon which the larvae feed during their pelagic phase. The consequences of these predictions remain speculative in the absence of empirical data on the interactive effects of warm temperatures on the metabolism, postprandial processes and growth responses of coral reef fish larvae. Here, we tested the effect of increased temperature on the metabolism, postprandial performance and fine-scale growth patterns of a coral reef fish (Amphiprion percula) in the latter half of its ~11-d larval phase. First, we measured the length and weight of fed versus fasted larvae (N = 340; mean body mass 4.1±0.05 mg) across fine temporal scales at a typical current summer temperature (28.5°C) and a temperature that is likely be encountered during warm summer periods later this century (31.5°C). Second, we measured routine metabolic rate (Mo2 routine) and the energetics of the postprandial processes (i.e., digestion, absorption and assimilation of a meal; termed specific dynamic action (SDA)) at both temperatures. Larvae fed voraciously when provided with food for a 12-hour period and displayed a temperature-independent increase in mass of 40.1% (28.5°C) and 42.6% (31.5°C), which was largely associated with the mass of prey in the gut. A subsequent 12-h fasting period revealed that the larvae had grown 21.2±4.8% (28.5°C) and 22.8±8.8% (31.5°C) in mass and 10.3±2.0% (28.5°C) and 7.8±2.6% (31.5°C) in length compared with pre-feeding values (no significant temperature effect). Mo2 routine was 55±16% higher at 31.5°C and peak Mo2 during the postprandial period was 28±11% higher at 31.5°C, yet elevated temperature had no significant effect on SDA (0.51±0.06 J at 28.5°C vs. 0.53±0.07 J at 31.5°C), SDA duration (6.0±0.6 h vs. 6.5±0.5 h), or the percent of total meal energy used for SDA (SDA coefficient: 10.1±1.3% vs. 13.0±1.7%). Our findings of higher Mo2 routine but similar SDA coefficient at high temperature provide the first empirical evidence that coral reef fish larvae may have to secure more food to attain similar growth rates during warm summer periods, and perhaps with chronically warmer conditions associated with climate change.

Herbivorous fishes, ecosystem function and mobile links on coral reefs

NASA Astrophysics Data System (ADS)

Welsh, J. Q.; Bellwood, D. R.

2014-06-01

Understanding large-scale movement of ecologically important taxa is key to both species and ecosystem management. Those species responsible for maintaining functional connectivity between habitats are often called mobile links and are regarded as essential elements of resilience. By providing connectivity, they support resilience across spatial scales. Most marine organisms, including fishes, have long-term, biogeographic-scale connectivity through larval movement. Although most reef species are highly site attached after larval settlement, some taxa may also be able to provide rapid, reef-scale connectivity as adults. On coral reefs, the identity of such taxa and the extent of their mobility are not yet known. We use acoustic telemetry to monitor the movements of Kyphosus vaigiensis, one of the few reef fishes that feeds on adult brown macroalgae. Unlike other benthic herbivorous fish species, it also exhibits large-scale (>2 km) movements. Individual K. vaigiensis cover, on average, a 2.5 km length of reef (11 km maximum) each day. These large-scale movements suggest that this species may act as a mobile link, providing functional connectivity, should the need arise, and helping to support functional processes across habitats and spatial scales. An analysis of published studies of home ranges in reef fishes found a consistent relationship between home range size and body length. K. vaigiensis is the sole herbivore to depart significantly from the expected home range-body size relationship, with home range sizes more comparable to exceptionally mobile large pelagic predators rather than other reef herbivores. While the large-scale movements of K. vaigiensis reveal its potential capacity to enhance resilience over large areas, it also emphasizes the potential limitations of small marine reserves to protect some herbivore populations.

The relative importance of local retention and inter-reef dispersal of neutrally buoyant material on coral reefs

NASA Astrophysics Data System (ADS)

Black, Kerry P.

1993-03-01

Reef-scale, eddy-resolving numerical models are applied to discriminate between local trapping of neutrally buoyant passive material coming from a natal reef versus trapping of this material on reefs downstream. A hydrodynamic model is coupled with a Lagrangian (nongridded) dispersal simulation to map the movement of material such as passive larvae within and between natural reefs. To simplify the interpretation, a number of schematic reef shapes, sizes and spacings were devised to represent the most common cases typifying Australia's Great Barrier Reef. Prior investigations have shown that coral reefs on the Great Barrier Reef may retain material for times equivalent to the pelagic dispersal period of many species. This paper explores whether larvae are more likely to settle on the natal reef, settle downstream or fail to settle at all. The modelling neglects active larval behaviour and treats the vertically well-mixed case of notionally weightless particles only. The crown-of-thorns starfish larvae with a pelagic dispersal period of at least 10 days are one example of this case. Larvae are most likely to be found near the natal reef rather than its downstream neighbour, mostly because the currents take the vertically well-mixed material around, rather than onto, the downstream reef. Of all the simulations, the highest numbers were found on natal reefs (e.g. 8% after 10 days) while downstream numbers mostly varied between 0 and 1% after 10 days. Particle numbers equalised only when spacing between the two reefs was less than the reef length (6 km), or when the downstream reef was in the direct path of the larval stream.

Possible natural hybridization of two morphologically distinct species of Acropora (Cnidaria, Scleractinia) in the Pacific: fertilization and larval survival rates.

PubMed

Isomura, Naoko; Iwao, Kenji; Fukami, Hironobu

2013-01-01

Natural hybridization of corals in the Indo-Pacific has been considered rather rare. However, field studies have observed many corals with intermediate interspecific or unusual morphologies. Given that the existence of F1 hybrids with intermediate interspecific morphologies has been proven in the Caribbean, hybrids may also inhabit the Indo-Pacific and occur more frequently than expected. In this study, we focused on two morphologically different species, Acropora florida and A. intermedia, and performed crossing experiments at Akajima Island, Japan. Results showed that these species could hybridize in both directions via eggs and sperm, but that fertilization rates significantly differed according to which species provided eggs. These results are similar to those reported from the Caribbean. Although all embryos developed normally to the planular larval stage, the developmental processes of some hybrid embryos were delayed by approximately 1 h compared with conspecific embryos, suggesting that fertilization occurred 1 h later in interspecific crosses than in intraspecific crosses. More successful hybridization could occur under conditions with low numbers of conspecific colonies. Additionally, a comparison of survival rates between hybrid and intraspecific larvae revealed that intra- and interspecific larvae produced from eggs of A. florida survived for significantly longer than those produced from eggs of A. intermedia. Considering these data, under specific conditions, hybrids can be expected to be produced and survive in nature in the Pacific. Furthermore, we identified one colony with intermediate morphology between A. florida and A. intermedia in the field. This colony was fertilized only by eggs of A. florida, with high fertilization rates, suggesting that this colony would be a hybrid of these two species and might be backcrossed.

Differential transcriptome analysis reveals genes related to cold tolerance in seabuckthorn carpenter moth, Eogystia hippophaecolus

PubMed Central

Hu, Ping; Wang, Tao; Tao, Jing; Zong, Shixiang

2017-01-01

Seabuckthorn carpenter moth, Eogystia hippophaecolus (Lepidoptera: Cossidae), is an important pest of sea buckthorn (Hippophae rhamnoides), which is a shrub that has significant ecological and economic value in China. E. hippophaecolus is highly cold tolerant, but limited studies have been conducted to elucidate the molecular mechanisms underlying its cold resistance. Here we sequenced the E. hippophaecolus transcriptome using RNA-Seq technology and performed de novo assembly from the short paired-end reads. We investigated the larval response to cold stress by comparing gene expression profiles between treatments. We obtained 118,034 unigenes, of which 22,161 were annotated with gene descriptions, conserved domains, gene ontology terms, and metabolic pathways. These resulted in 57 GO terms and 193 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. By comparing transcriptome profiles for differential gene expression, we identified many differentially expressed proteins and genes, including heat shock proteins and cuticular proteins which have previously been reported to be involved in cold resistance of insects. This study provides a global transcriptome analysis and an assessment of differential gene expression in E. hippophaecolus under cold stress. We found seven differential expressed genes in common between developmental stages, which were verified with qPCR. Our findings facilitate future genomic studies aimed at improving our understanding of the molecular mechanisms underlying the response of insects to low temperatures. PMID:29131867

Differential transcriptome analysis reveals genes related to cold tolerance in seabuckthorn carpenter moth, Eogystia hippophaecolus.

PubMed

Cui, Mingming; Hu, Ping; Wang, Tao; Tao, Jing; Zong, Shixiang

2017-01-01

Seabuckthorn carpenter moth, Eogystia hippophaecolus (Lepidoptera: Cossidae), is an important pest of sea buckthorn (Hippophae rhamnoides), which is a shrub that has significant ecological and economic value in China. E. hippophaecolus is highly cold tolerant, but limited studies have been conducted to elucidate the molecular mechanisms underlying its cold resistance. Here we sequenced the E. hippophaecolus transcriptome using RNA-Seq technology and performed de novo assembly from the short paired-end reads. We investigated the larval response to cold stress by comparing gene expression profiles between treatments. We obtained 118,034 unigenes, of which 22,161 were annotated with gene descriptions, conserved domains, gene ontology terms, and metabolic pathways. These resulted in 57 GO terms and 193 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. By comparing transcriptome profiles for differential gene expression, we identified many differentially expressed proteins and genes, including heat shock proteins and cuticular proteins which have previously been reported to be involved in cold resistance of insects. This study provides a global transcriptome analysis and an assessment of differential gene expression in E. hippophaecolus under cold stress. We found seven differential expressed genes in common between developmental stages, which were verified with qPCR. Our findings facilitate future genomic studies aimed at improving our understanding of the molecular mechanisms underlying the response of insects to low temperatures.

Comparative Transcriptome Analysis of Bombyx mori (Lepidoptera) Larval Midgut Response to BmNPV in Susceptible and Near-Isogenic Resistant Strains

PubMed Central

Geng, Lei; Xu, Jia-Ping; Yu, Dong; Zhang, Shang-Zhi; Ma, Yan; Fei, Dong-Qiong

2016-01-01

Bombyx mori nucleopolyhedrovirus (BmNPV) is one of the primary pathogens causing severe economic losses in sericulture. However, the molecular mechanism of silkworm resistance to BmNPV remains largely unknown. Here, the recurrent parent P50 (susceptible strain) and the near-isogenic line BC9 (resistance strain) were used in a comparative transcriptome study examining the response to infection with BmNPV. A total of 14,300 unigenes were obtained from two different resistant strains; of these, 869 differentially expressed genes (DEGs) were identified after comparing the four transcriptomes. Many DEGs associated with protein metabolism, cytoskeleton, and apoptosis may be involved in the host response to BmNPV infection. Moreover, some immunity related genes were also altered following BmNPV infection. Specifically, after removing genetic background and individual immune stress response genes, 22 genes were found to be potentially involved in repressing BmNPV infection. These genes were related to transport, virus replication, intracellular innate immune, and apoptosis. Our study provided an overview of the molecular mechanism of silkworm resistance to BmNPV infection and laid a foundation for controlling BmNPV in the future. PMID:27168061

Transcriptome Sequencing and Developmental Regulation of Gene Expression in Anopheles aquasalis

PubMed Central

Silva, Maria C. P.; Lopes, Adriana R.; Barros, Michele S.; Sá-Nunes, Anderson; Kojin, Bianca B.; Carvalho, Eneas; Suesdek, Lincoln; Silva-Neto, Mário Alberto C.; James, Anthony A.; Capurro, Margareth L.

2014-01-01

Background Anopheles aquasalis is a major malaria vector in coastal areas of South and Central America where it breeds preferentially in brackish water. This species is very susceptible to Plasmodium vivax and it has been already incriminated as responsible vector in malaria outbreaks. There has been no high-throughput investigation into the sequencing of An. aquasalis genes, transcripts and proteins despite its epidemiological relevance. Here we describe the sequencing, assembly and annotation of the An. aquasalis transcriptome. Methodology/Principal Findings A total of 419 thousand cDNA sequence reads, encompassing 164 million nucleotides, were assembled in 7544 contigs of ≥2 sequences, and 1999 singletons. The majority of the An. aquasalis transcripts encode proteins with their closest counterparts in another neotropical malaria vector, An. darlingi. Several analyses in different protein databases were used to annotate and predict the putative functions of the deduced An. aquasalis proteins. Larval and adult-specific transcripts were represented by 121 and 424 contig sequences, respectively. Fifty-one transcripts were only detected in blood-fed females. The data also reveal a list of transcripts up- or down-regulated in adult females after a blood meal. Transcripts associated with immunity, signaling networks and blood feeding and digestion are discussed. Conclusions/Significance This study represents the first large-scale effort to sequence the transcriptome of An. aquasalis. It provides valuable information that will facilitate studies on the biology of this species and may lead to novel strategies to reduce malaria transmission on the South American continent. The An. aquasalis transcriptome is accessible at http://exon.niaid.nih.gov/transcriptome/An_aquasalis/Anaquexcel.xlsx. PMID:25033462

Genetic Diversity and Connectivity in the Threatened Staghorn Coral (Acropora cervicornis) in Florida

PubMed Central

Hemond, Elizabeth M.; Vollmer, Steven V.

2010-01-01

Over the past three decades, populations of the dominant shallow water Caribbean corals, Acropora cervicornis and A. palmata, have been devastated by white-band disease (WBD), resulting in the listing of both species as threatened under the U.S. Endangered Species Act. A key to conserving these threatened corals is understanding how their populations are genetically interconnected throughout the greater Caribbean. Genetic research has demonstrated that gene flow is regionally restricted across the Caribbean in both species. Yet, despite being an important site of coral reef research, little genetic data has been available for the Florida Acropora, especially for the staghorn coral, A. cervicornis. In this study, we present new mitochondrial DNA sequence data from 52 A. cervicornis individuals from 22 sites spread across the upper and lower Florida Keys, which suggest that Florida's A. cervicornis populations are highly genetically interconnected (FST = −0.081). Comparison between Florida and existing mtDNA data from six regional Caribbean populations indicates that Florida possesses high levels of standing genetic diversity (h = 0.824) relative to the rest of the greater Caribbean (h = 0.701±0.043). We find that the contemporary level of gene flow across the greater Caribbean, including Florida, is restricted ( = 0.117), but evidence from shared haplotypes suggests the Western Caribbean has historically been a source of genetic variation for Florida. Despite the current patchiness of A. cervicornis in Florida, the relatively high genetic diversity and connectivity within Florida suggest that this population may have sufficient genetic variation to be viable and resilient to environmental perturbation and disease. Limited genetic exchange across regional populations of the greater Caribbean, including Florida, indicates that conservation efforts for A. cervicornis should focus on maintaining and managing populations locally rather than relying on larval inputs from elsewhere. PMID:20111583

Bipartite life cycle of coral reef fishes promotes increasing shape disparity of the head skeleton during ontogeny: an example from damselfishes (Pomacentridae)

PubMed Central

2011-01-01

Background Quantitative studies of the variation of disparity during ontogeny exhibited by the radiation of coral reef fishes are lacking. Such studies dealing with the variation of disparity, i.e. the diversity of organic form, over ontogeny could be a first step in detecting evolutionary mechanisms in these fishes. The damselfishes (Pomacentridae) have a bipartite life-cycle, as do the majority of demersal coral reef fishes. During their pelagic dispersion phase, all larvae feed on planktonic prey. On the other hand, juveniles and adults associated with the coral reef environment show a higher diversity of diets. Using geometric morphometrics, we study the ontogenetic dynamic of shape disparity of different head skeletal units (neurocranium, suspensorium and opercle, mandible and premaxilla) in this fish family. We expected that larvae of different species might be relatively similar in shapes. Alternatively, specialization may become notable even in the juvenile and adult phase. Results The disparity levels increase significantly throughout ontogeny for each skeletal unit. At settlement, all larval shapes are already species-specific. Damselfishes show high levels of ontogenetic allometry during their post-settlement growth. The divergence of allometric patterns largely explains the changes in patterns and levels of shape disparity over ontogeny. The rate of shape change and the length of ontogenetic trajectories seem to be less variable among species. We also show that the high levels of shape disparity at the adult stage are correlated to a higher level of ecological and functional diversity in this stage. Conclusion Diversification throughout ontogeny of damselfishes results from the interaction among several developmental novelties enhancing disparity. The bipartite life-cycle of damselfishes exemplifies a case where the variation of environmental factors, i.e. the transition from the more homogeneous oceanic environment to the coral reef offering a wide range of feeding habits, promotes increasing shape disparity of the head skeleton over the ontogeny of fishes. PMID:21450094

Climate change and larval transport in the ocean: fractional effects from physical and physiological factors.

PubMed

Kendall, Matthew S; Poti, Matt; Karnauskas, Kristopher B

2016-04-01

Changes in larval import, export, and self-seeding will affect the resilience of coral reef ecosystems. Climate change will alter the ocean currents that transport larvae and also increase sea surface temperatures (SST), hastening development, and shortening larval durations. Here, we use transport simulations to estimate future larval connectivity due to: (1) physical transport of larvae from altered circulation alone, and (2) the combined effects of altered currents plus physiological response to warming. Virtual larvae from islands throughout Micronesia were moved according to present-day and future ocean circulation models. The Hybrid Coordinate Ocean Model (HYCOM) spanning 2004-2012 represented present-day currents. For future currents, we altered HYCOM using analysis from the National Center for Atmospheric Research Community Earth System Model, version 1-Biogeochemistry, Representative Concentration Pathway 8.5 experiment. Based on the NCAR model, regional SST is estimated to rise 2.74 °C which corresponds to a ~17% decline in larval duration for some taxa. This reduction was the basis for a separate set of simulations. Results predict an increase in self-seeding in 100 years such that 62-76% of islands experienced increased self-seeding, there was an average domainwide increase of ~1-3% points in self-seeding, and increases of up to 25% points for several individual islands. When changed currents alone were considered, approximately half (i.e., random) of all island pairs experienced decreased connectivity but when reduced PLD was added as an effect, ~65% of connections were weakened. Orientation of archipelagos relative to currents determined the directional bias in connectivity changes. There was no universal relationship between climate change and connectivity applicable to all taxa and settings. Islands that presently export large numbers of larvae but that also maintain or enhance this role into the future should be the focus of conservation measures that promote long-term resilience of larval supply. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Pelagic larval duration and settlement size of a reef fish are spatially consistent, but post-settlement growth varies at the reef scale

NASA Astrophysics Data System (ADS)

Leahy, Susannah M.; Russ, Garry R.; Abesamis, Rene A.

2015-12-01

Recent research has demonstrated that, despite a pelagic larval stage, many coral reef fishes disperse over relatively small distances, leading to well-connected populations on scales of 0-30 km. Although variation in key biological characteristics has been explored on the scale of 100-1000 s of km, it has rarely been explored at the scale relevant to actual larval dispersal and population connectivity on ecological timescales. In this study, we surveyed the habitat and collected specimens ( n = 447) of juvenile butterflyfish, Chaetodon vagabundus, at nine sites along an 80-km stretch of coastline in the central Philippines to identify variation in key life history parameters at a spatial scale relevant to population connectivity. Mean pelagic larval duration (PLD) was 24.03 d (SE = 0.16 d), and settlement size was estimated to be 20.54 mm total length (TL; SE = 0.61 mm). Both traits were spatially consistent, although this PLD is considerably shorter than that reported elsewhere. In contrast, post-settlement daily growth rates, calculated from otolith increment widths from 1 to 50 d post-settlement, varied strongly across the study region. Elevated growth rates were associated with rocky habitats that this species is known to recruit to, but were strongly negatively correlated with macroalgal cover and exhibited negative density dependence with conspecific juveniles. Larger animals had lower early (first 50 d post-settlement) growth rates than smaller animals, even after accounting for seasonal variation in growth rates. Both VBGF and Gompertz models provided good fits to post-settlement size-at-age data ( n = 447 fish), but the VBGF's estimate of asymptotic length ( L ∞ = 168 mm) was more consistent with field observations of maximum fish length. Our findings indicate that larval characteristics are consistent at the spatial scale at which populations are likely well connected, but that site-level biological differences develop post-settlement, most likely as a result of key differences in quality of recruitment habitat.

Integrating larval connectivity with local demography reveals regional dynamics of a marine metapopulation.

PubMed

Johnson, Darren W; Christie, Mark R; Pusack, Timothy J; Stallings, Christopher D; Hixon, Mark A

2018-06-01

Many ocean species exist within what are called marine metapopulations: networks of otherwise isolated local populations connected by the exchange of larval offspring. In order to manage these species as effectively as possible (e.g., by designing and implementing effective networks of marine protected areas), we must know how many offspring are produced within each local population (i.e., local demography), and where those offspring disperse (i.e., larval connectivity). Although there is much interest in estimating connectivity in the relatively simple sense of identifying the locations of spawning parents and their settling offspring, true measures of demographic connectivity that account for among-site variation in offspring production have been lacking. We combined detailed studies of local reproductive output and larval dispersal of a coral reef fish to quantify demographic connectivity within a regional metapopulation that included four widely spaced islands in the Bahamas. We present a new method for estimating demographic connectivity when the levels of dispersal among populations are inferred by the collection of genetically "tagged" offspring. We estimated that 13.3% of recruits returned to natal islands, on average (95% CI = 1.1-50.3%), that local retention was high on one of the islands (41%, 95% CI = 6.0-97.0%), and that larval connectivity was appreciable, even between islands 129 km apart (mean = 1.6%, 95% CI = 0.20-8.8%). Our results emphasize the importance of properly integrating measurements of production with measurements of connectivity. Had we not accounted for among-site variation in offspring production, our estimates of connectivity would have been inaccurate by a factor as much as 6.5. At a generational timescale, lifetime offspring production varied substantially (a fivefold difference among islands) and the importance of each island to long-term metapopulation growth was dictated by both larval production and connectivity. At the scale of our study (local populations inhabiting 5-ha reefs), the regional metapopulation could not grow without external input. However, an exploratory analysis simulating a network of four marine protected areas suggested that reserves of >65 ha each would ensure persistence of this network. Thus, integrating studies of larval connectivity and local demography hold promise for both managing and conserving marine metapopulations effectively. © 2018 by the Ecological Society of America.

Coral Carbonic Anhydrases: Regulation by Ocean Acidification.

PubMed

Zoccola, Didier; Innocenti, Alessio; Bertucci, Anthony; Tambutté, Eric; Supuran, Claudiu T; Tambutté, Sylvie

2016-06-03

Global change is a major threat to the oceans, as it implies temperature increase and acidification. Ocean acidification (OA) involving decreasing pH and changes in seawater carbonate chemistry challenges the capacity of corals to form their skeletons. Despite the large number of studies that have investigated how rates of calcification respond to ocean acidification scenarios, comparatively few studies tackle how ocean acidification impacts the physiological mechanisms that drive calcification itself. The aim of our paper was to determine how the carbonic anhydrases, which play a major role in calcification, are potentially regulated by ocean acidification. For this we measured the effect of pH on enzyme activity of two carbonic anhydrase isoforms that have been previously characterized in the scleractinian coral Stylophora pistillata. In addition we looked at gene expression of these enzymes in vivo. For both isoforms, our results show (1) a change in gene expression under OA (2) an effect of OA and temperature on carbonic anhydrase activity. We suggest that temperature increase could counterbalance the effect of OA on enzyme activity. Finally we point out that caution must, thus, be taken when interpreting transcriptomic data on carbonic anhydrases in ocean acidification and temperature stress experiments, as the effect of these stressors on the physiological function of CA will depend both on gene expression and enzyme activity.

Genetic connectivity in scleractinian corals across the Northern Gulf of Mexico: oil/gas platforms, and relationship to the Flower Garden Banks.

PubMed

Sammarco, Paul W; Brazeau, Daniel A; Sinclair, James

2012-01-01

The 3,000 oil/gas structures currently deployed in the northern Gulf of Mexico (GOM) provide hard substratum for marine organisms in a region where such has been rare since the Holocene. The major exception to this are the Flower Garden Banks (FGB). Corals are known to have colonized oil/gas platforms around the FGB, facilitating biogeographic expansion. We ask the question, what are the patterns of genetic affinity in these coral populations. We sampled coral tissue from populations of two species occurring on oil and gas platforms: Madracis decactis (hermatype) and Tubastraea coccinea (invasive ahermatype). We sampled 28 platforms along four transects from 20 km offshore to the continental shelf edge off 1) Matagorda Island, TX; 2) Lake Sabine, TX; 3) Terrebonne Bay, LA; and 4) Mobile, AL. The entire population of M. decactis was sampled between depths of 5 m and 37 m. T. coccinea populations were sub-sampled. Genetic variation was assessed using the PCR-based Amplified Fragment Length Polymorphisms (AFLPs). Data were analyzed via AFLPOP and STRUCTURE. Genetic connectivity among M. decactis platform populations was highest near the FGB and decreased to the east. Connectivity increased again in the eastern sector, indicating isolation between the populations from different sides of the Mississippi River (Transects 3 and 4). A point-drop in genetic affinity (relatedness) at the shelf edge south of Terrebonne Bay, LA indicated a population differing from all others in the northern GOM. Genetic affinities among T. coccinea were highest in the west and decreased to the east. Very low genetic affinities off Mobile, AL indicated a dramatic difference between those populations and those west of the Mississippi River, apparently a formidable barrier to larval dispersal.

Genetic Connectivity in Scleractinian Corals across the Northern Gulf of Mexico: Oil/Gas Platforms, and Relationship to the Flower Garden Banks

PubMed Central

Sammarco, Paul W.; Brazeau, Daniel A.; Sinclair, James

2012-01-01

The 3,000 oil/gas structures currently deployed in the northern Gulf of Mexico (GOM) provide hard substratum for marine organisms in a region where such has been rare since the Holocene. The major exception to this are the Flower Garden Banks (FGB). Corals are known to have colonized oil/gas platforms around the FGB, facilitating biogeographic expansion. We ask the question, what are the patterns of genetic affinity in these coral populations. We sampled coral tissue from populations of two species occurring on oil and gas platforms: Madracis decactis (hermatype) and Tubastraea coccinea (invasive ahermatype). We sampled 28 platforms along four transects from 20 km offshore to the continental shelf edge off 1) Matagorda Island, TX; 2) Lake Sabine, TX; 3) Terrebonne Bay, LA; and 4) Mobile, AL. The entire population of M. decactis was sampled between depths of 5 m and 37 m. T. coccinea populations were sub-sampled. Genetic variation was assessed using the PCR-based Amplified Fragment Length Polymorphisms (AFLPs). Data were analyzed via AFLPOP and STRUCTURE. Genetic connectivity among M. decactis platform populations was highest near the FGB and decreased to the east. Connectivity increased again in the eastern sector, indicating isolation between the populations from different sides of the Mississippi River (Transects 3 and 4). A point-drop in genetic affinity (relatedness) at the shelf edge south of Terrebonne Bay, LA indicated a population differing from all others in the northern GOM. Genetic affinities among T. coccinea were highest in the west and decreased to the east. Very low genetic affinities off Mobile, AL indicated a dramatic difference between those populations and those west of the Mississippi River, apparently a formidable barrier to larval dispersal. PMID:22558066

Volcanic ash supports a diverse bacterial community in a marine mesocosm.

PubMed

Witt, V; Ayris, P M; Damby, D E; Cimarelli, C; Kueppers, U; Dingwell, D B; Wörheide, G

2017-05-01

Shallow-water coral reef ecosystems, particularly those already impaired by anthropogenic pressures, may be highly sensitive to disturbances from natural catastrophic events, such as volcanic eruptions. Explosive volcanic eruptions expel large quantities of silicate ash particles into the atmosphere, which can disperse across millions of square kilometres and deposit into coral reef ecosystems. Following heavy ash deposition, mass mortality of reef biota is expected, but little is known about the recovery of post-burial reef ecosystems. Reef regeneration depends partly upon the capacity of the ash deposit to be colonised by waterborne bacterial communities and may be influenced to an unknown extent by the physiochemical properties of the ash substrate itself. To determine the potential for volcanic ash to support pioneer bacterial colonisation, we exposed five well-characterised volcanic and coral reef substrates to a marine aquarium under low light conditions for 3 months: volcanic ash, synthetic volcanic glass, carbonate reef sand, calcite sand and quartz sand. Multivariate statistical analysis of Automated Ribosomal Intergenic Spacer Analysis (ARISA) fingerprinting data demonstrates clear segregation of volcanic substrates from the quartz and coral reef substrates over 3 months of bacterial colonisation. Overall bacterial diversity showed shared and substrate-specific bacterial communities; however, the volcanic ash substrate supported the most diverse bacterial community. These data suggest a significant influence of substrate properties (composition, granulometry and colour) on bacterial settlement. Our findings provide first insights into physicochemical controls on pioneer bacterial colonisation of volcanic ash and highlight the potential for volcanic ash deposits to support bacterial diversity in the aftermath of reef burial, on timescales that could permit cascading effects on larval settlement. © 2017 The Authors. Geobiology Published by John Wiley & Sons Ltd.

A Network of Chromatin Factors Is Regulating the Transition to Postembryonic Development in Caenorhabditis elegans

PubMed Central

Erdelyi, Peter; Wang, Xing; Suleski, Marina; Wicky, Chantal

2016-01-01

Mi2 proteins are evolutionarily conserved, ATP-dependent chromatin remodelers of the CHD family that play key roles in stem cell differentiation and reprogramming. In Caenorhabditis elegans, the let-418 gene encodes one of the two Mi2 homologs, which is part of at least two chromatin complexes, namely the Nucleosome Remodeling and histone Deacetylase (NuRD) complex and the MEC complex, and functions in larval development, vulval morphogenesis, lifespan regulation, and cell fate determination. To explore the mechanisms involved in the action of LET-418/Mi2, we performed a genome-wide RNA interference (RNAi) screen for suppressors of early larval arrest associated with let-418 mutations. We identified 29 suppressor genes, of which 24 encode chromatin regulators, mostly orthologs of proteins present in transcriptional activator complexes. The remaining five genes vary broadly in their predicted functions. All suppressor genes could suppress multiple aspects of the let-418 phenotype, including developmental arrest and ectopic expression of germline genes in the soma. Analysis of available transcriptomic data and quantitative PCR revealed that LET-418 and the suppressors of early larval arrest are regulating common target genes. These suppressors might represent direct competitors of LET-418 complexes for chromatin regulation of crucial genes involved in the transition to postembryonic development. PMID:28007841

A Network of Chromatin Factors Is Regulating the Transition to Postembryonic Development in Caenorhabditis elegans.

PubMed

Erdelyi, Peter; Wang, Xing; Suleski, Marina; Wicky, Chantal

2017-02-09

Mi2 proteins are evolutionarily conserved, ATP-dependent chromatin remodelers of the CHD family that play key roles in stem cell differentiation and reprogramming. In Caenorhabditis elegans , the let-418 gene encodes one of the two Mi2 homologs, which is part of at least two chromatin complexes, namely the Nucleosome Remodeling and histone Deacetylase (NuRD) complex and the MEC complex, and functions in larval development, vulval morphogenesis, lifespan regulation, and cell fate determination. To explore the mechanisms involved in the action of LET-418/Mi2, we performed a genome-wide RNA interference (RNAi) screen for suppressors of early larval arrest associated with let-418 mutations. We identified 29 suppressor genes, of which 24 encode chromatin regulators, mostly orthologs of proteins present in transcriptional activator complexes. The remaining five genes vary broadly in their predicted functions. All suppressor genes could suppress multiple aspects of the let-418 phenotype, including developmental arrest and ectopic expression of germline genes in the soma. Analysis of available transcriptomic data and quantitative PCR revealed that LET-418 and the suppressors of early larval arrest are regulating common target genes. These suppressors might represent direct competitors of LET-418 complexes for chromatin regulation of crucial genes involved in the transition to postembryonic development. Copyright © 2017 Erdelyi et al.

Contrasting evolutionary patterns in two reef-corals and their possible relationship to life history traits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foster, A.B.

1985-01-01

Multivariate statistical analyses have been used to redefine species within two genera of reef-corals (Porites and Montastraea) and to trace their evolutionary patterns through a continuous sequence from late Miocene to early Pliocene time. The material studied consists of populations sampled at regular intervals through four stratigraphic sections in the northern Dominican Republic. The results show that species in the first genus (Porites) have relatively short durations, morphologic stability, and narrow spatial distributions. Their overall evolutionary history is characterized by short periods of radiation and widespread extinction, separated by longer periods of stasis. In contrast, species in the second genusmore » (Montastraea) exhibit various different durations and distributions and directional morphologic trends. These differences in patterns may be related to the dissimilar life histories of the two genera. Patterns in the first genus appear more common in organisms having high larval recruitment, high mortality, high genetic variation, and less morphologic distance between species. Patterns in the second genus occur more frequently in slower growing, phenotypically plastic organisms experiencing less recruitment and mortality and showing more morphologic distance between species.« less

Exploration of immunoglobulin transcriptomes from mice immunized with three-finger toxins and phospholipases A2 from the Central American coral snake, Micrurus nigrocinctus.

PubMed

Laustsen, Andreas H; Engmark, Mikael; Clouser, Christopher; Timberlake, Sonia; Vigneault, Francois; Gutiérrez, José María; Lomonte, Bruno

2017-01-01

Snakebite envenomings represent a neglected public health issue in many parts of the rural tropical world. Animal-derived antivenoms have existed for more than a hundred years and are effective in neutralizing snake venom toxins when timely administered. However, the low immunogenicity of many small but potent snake venom toxins represents a challenge for obtaining a balanced immune response against the medically relevant components of the venom. Here, we employ high-throughput sequencing of the immunoglobulin (Ig) transcriptome of mice immunized with a three-finger toxin and a phospholipase A 2 from the venom of the Central American coral snake, Micrurus nigrocinctus. Although exploratory in nature, our indicate results showed that only low frequencies of mRNA encoding IgG isotypes, the most relevant isotype for therapeutic purposes, were present in splenocytes of five mice immunized with 6 doses of the two types of toxins over 90 days. Furthermore, analysis of Ig heavy chain transcripts showed that no particular combination of variable (V) and joining (J) gene segments had been selected in the immunization process, as would be expected after a strong humoral immune response to a single antigen. Combined with the titration of toxin-specific antibodies in the sera of immunized mice, these data support the low immunogenicity of three-finger toxins and phospholipases A 2 found in M. nigrocinctus venoms, and highlight the need for future studies analyzing the complexity of antibody responses to toxins at the molecular level.

Symbiosis induces widespread changes in the proteome of the model cnidarian Aiptasia.

PubMed

Oakley, Clinton A; Ameismeier, Michael F; Peng, Lifeng; Weis, Virginia M; Grossman, Arthur R; Davy, Simon K

2016-07-01

Coral reef ecosystems are metabolically founded on the mutualism between corals and photosynthetic dinoflagellates of the genus Symbiodinium. The glass anemone Aiptasia sp. has become a tractable model for this symbiosis, and recent advances in genetic information have enabled the use of mass spectrometry-based proteomics in this model. We utilized label-free liquid chromatography electrospray-ionization tandem mass spectrometry to analyze the effects of symbiosis on the proteomes of symbiotic and aposymbiotic Aiptasia. We identified and obtained relative quantification of more than 3,300 proteins in 1,578 protein clusters, with 81 protein clusters showing significantly different expression between symbiotic states. Symbiotic anemones showed significantly higher expression of proteins involved in lipid storage and transport, nitrogen transport and cycling, intracellular trafficking, endocytosis and inorganic carbon transport. These changes reflect shifts in host metabolism and nutrient reserves due to increased nutritional exchange with the symbionts, as well as mechanisms for supplying inorganic nutrients to the algae. Aposymbiotic anemones exhibited increased expression of multiple systems responsible for mediating reactive oxygen stress, suggesting that the host derives direct or indirect protection from oxidative stress while in symbiosis. Aposymbiotic anemones also increased their expression of an array of proteases and chitinases, indicating a metabolic shift from autotrophy to heterotrophy. These results provide a comprehensive Aiptasia proteome with more direct relative quantification of protein abundance than transcriptomic methods. The extension of "omics" techniques to this model system will allow more powerful studies of coral physiology, ecosystem function, and the effects of biotic and abiotic stress on the coral-dinoflagellate mutualism. © 2015 John Wiley & Sons Ltd.

Extensive Differences in Gene Expression Between Symbiotic and Aposymbiotic Cnidarians

PubMed Central

Lehnert, Erik M.; Mouchka, Morgan E.; Burriesci, Matthew S.; Gallo, Natalya D.; Schwarz, Jodi A.; Pringle, John R.

2013-01-01

Coral reefs provide habitats for a disproportionate number of marine species relative to the small area of the oceans that they occupy. The mutualism between the cnidarian animal hosts and their intracellular dinoflagellate symbionts provides the nutritional foundation for coral growth and formation of reef structures, because algal photosynthesis can provide >90% of the total energy of the host. Disruption of this symbiosis (“coral bleaching”) is occurring on a large scale due primarily to anthropogenic factors and poses a major threat to the future of coral reefs. Despite the importance of this symbiosis, the cellular mechanisms involved in its establishment, maintenance, and breakdown remain largely unknown. We report our continued development of genomic tools to study these mechanisms in Aiptasia, a small sea anemone with great promise as a model system for studies of cnidarian–dinoflagellate symbiosis. Specifically, we have generated de novo assemblies of the transcriptomes of both a clonal line of symbiotic anemones and their endogenous dinoflagellate symbionts. We then compared transcript abundances in animals with and without dinoflagellates. This analysis identified >900 differentially expressed genes and allowed us to generate testable hypotheses about the cellular functions affected by symbiosis establishment. The differentially regulated transcripts include >60 encoding proteins that may play roles in transporting various nutrients between the symbiotic partners; many more encoding proteins functioning in several metabolic pathways, providing clues regarding how the transported nutrients may be used by the partners; and several encoding proteins that may be involved in host recognition and tolerance of the dinoflagellate. PMID:24368779

Oyster reproduction is affected by exposure to polystyrene microplastics

PubMed Central

Sussarellu, Rossana; Suquet, Marc; Thomas, Yoann; Lambert, Christophe; Fabioux, Caroline; Pernet, Marie Eve Julie; Le Goïc, Nelly; Quillien, Virgile; Mingant, Christian; Epelboin, Yanouk; Corporeau, Charlotte; Guyomarch, Julien; Robbens, Johan; Paul-Pont, Ika; Soudant, Philippe; Huvet, Arnaud

2016-01-01

Plastics are persistent synthetic polymers that accumulate as waste in the marine environment. Microplastic (MP) particles are derived from the breakdown of larger debris or can enter the environment as microscopic fragments. Because filter-feeder organisms ingest MP while feeding, they are likely to be impacted by MP pollution. To assess the impact of polystyrene microspheres (micro-PS) on the physiology of the Pacific oyster, adult oysters were experimentally exposed to virgin micro-PS (2 and 6 µm in diameter; 0.023 mg·L−1) for 2 mo during a reproductive cycle. Effects were investigated on ecophysiological parameters; cellular, transcriptomic, and proteomic responses; fecundity; and offspring development. Oysters preferentially ingested the 6-µm micro-PS over the 2-µm-diameter particles. Consumption of microalgae and absorption efficiency were significantly higher in exposed oysters, suggesting compensatory and physical effects on both digestive parameters. After 2 mo, exposed oysters had significant decreases in oocyte number (−38%), diameter (−5%), and sperm velocity (−23%). The D-larval yield and larval development of offspring derived from exposed parents decreased by 41% and 18%, respectively, compared with control offspring. Dynamic energy budget modeling, supported by transcriptomic profiles, suggested a significant shift of energy allocation from reproduction to structural growth, and elevated maintenance costs in exposed oysters, which is thought to be caused by interference with energy uptake. Molecular signatures of endocrine disruption were also revealed, but no endocrine disruptors were found in the biological samples. This study provides evidence that micro-PS cause feeding modifications and reproductive disruption in oysters, with significant impacts on offspring. PMID:26831072

Transcriptomic survey of the midgut of Anthonomus grandis (Coleoptera: Curculionidae).

PubMed

Salvador, Ricardo; Príncipi, Darío; Berretta, Marcelo; Fernández, Paula; Paniego, Norma; Sciocco-Cap, Alicia; Hopp, Esteban

2014-01-01

Anthonomus grandis Boheman is a key pest in cotton crops in the New World. Its larval stage develops within the flower bud using it as food and as protection against its predators. This behavior limits the effectiveness of its control using conventional insecticide applications and biocontrol techniques. In spite of its importance, little is known about its genome sequence and, more important, its specific expression in key organs like the midgut. Total mRNA isolated from larval midguts was used for pyrosequencing. Sequence reads were assembled and annotated to generate a unigene data set. In total, 400,000 reads from A. grandis midgut with an average length of 237 bp were assembled and combined into 20,915 contigs. The assembled reads fell into 6,621 genes models. BlastX search using the NCBI-NR database showed that 3,006 unigenes had significant matches to known sequences. Gene Ontology (GO) mapping analysis evidenced that A. grandis is able to transcripts coding for proteins involved in catalytic processing of macromolecules that allows its adaptation to very different feeding source scenarios. Furthermore, transcripts encoding for proteins involved in detoxification mechanisms such as p450 genes, glutathione-S-transferase, and carboxylesterases are also expressed. This is the first report of a transcriptomic study in A. grandis and the largest set of sequence data reported for this species. These data are valuable resources to expand the knowledge of this insect group and could be used in the design of new control strategies based in molecular information. © The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.

Transcriptomic Survey of the Midgut of Anthonomus grandis (Coleoptera: Curculionidae)

PubMed Central

Salvador, Ricardo; Príncipi, Darío; Berretta, Marcelo; Fernández, Paula; Paniego, Norma; Sciocco-Cap, Alicia; Hopp, Esteban

2014-01-01

Abstract Anthonomus grandis Boheman is a key pest in cotton crops in the New World. Its larval stage develops within the flower bud using it as food and as protection against its predators. This behavior limits the effectiveness of its control using conventional insecticide applications and biocontrol techniques. In spite of its importance, little is known about its genome sequence and, more important, its specific expression in key organs like the midgut. Total mRNA isolated from larval midguts was used for pyrosequencing. Sequence reads were assembled and annotated to generate a unigene data set. In total, 400,000 reads from A. grandis midgut with an average length of 237 bp were assembled and combined into 20,915 contigs. The assembled reads fell into 6,621 genes models. BlastX search using the NCBI-NR database showed that 3,006 unigenes had significant matches to known sequences. Gene Ontology (GO) mapping analysis evidenced that A. grandis is able to transcripts coding for proteins involved in catalytic processing of macromolecules that allows its adaptation to very different feeding source scenarios. Furthermore, transcripts encoding for proteins involved in detoxification mechanisms such as p450 genes, glutathione-S-transferase , and carboxylesterases are also expressed. This is the first report of a transcriptomic study in A. grandis and the largest set of sequence data reported for this species. These data are valuable resources to expand the knowledge of this insect group and could be used in the design of new control strategies based in molecular information. PMID:25473064

Oyster reproduction is affected by exposure to polystyrene microplastics.

PubMed

Sussarellu, Rossana; Suquet, Marc; Thomas, Yoann; Lambert, Christophe; Fabioux, Caroline; Pernet, Marie Eve Julie; Le Goïc, Nelly; Quillien, Virgile; Mingant, Christian; Epelboin, Yanouk; Corporeau, Charlotte; Guyomarch, Julien; Robbens, Johan; Paul-Pont, Ika; Soudant, Philippe; Huvet, Arnaud

2016-03-01

Plastics are persistent synthetic polymers that accumulate as waste in the marine environment. Microplastic (MP) particles are derived from the breakdown of larger debris or can enter the environment as microscopic fragments. Because filter-feeder organisms ingest MP while feeding, they are likely to be impacted by MP pollution. To assess the impact of polystyrene microspheres (micro-PS) on the physiology of the Pacific oyster, adult oysters were experimentally exposed to virgin micro-PS (2 and 6 µm in diameter; 0.023 mg·L(-1)) for 2 mo during a reproductive cycle. Effects were investigated on ecophysiological parameters; cellular, transcriptomic, and proteomic responses; fecundity; and offspring development. Oysters preferentially ingested the 6-µm micro-PS over the 2-µm-diameter particles. Consumption of microalgae and absorption efficiency were significantly higher in exposed oysters, suggesting compensatory and physical effects on both digestive parameters. After 2 mo, exposed oysters had significant decreases in oocyte number (-38%), diameter (-5%), and sperm velocity (-23%). The D-larval yield and larval development of offspring derived from exposed parents decreased by 41% and 18%, respectively, compared with control offspring. Dynamic energy budget modeling, supported by transcriptomic profiles, suggested a significant shift of energy allocation from reproduction to structural growth, and elevated maintenance costs in exposed oysters, which is thought to be caused by interference with energy uptake. Molecular signatures of endocrine disruption were also revealed, but no endocrine disruptors were found in the biological samples. This study provides evidence that micro-PS cause feeding modifications and reproductive disruption in oysters, with significant impacts on offspring.

Detailed transcriptome description of the neglected cestode Taenia multiceps.

PubMed

Wu, Xuhang; Fu, Yan; Yang, Deying; Zhang, Runhui; Zheng, Wanpeng; Nie, Huaming; Xie, Yue; Yan, Ning; Hao, Guiying; Gu, Xiaobin; Wang, Shuxian; Peng, Xuerong; Yang, Guangyou

2012-01-01

The larval stage of Taenia multiceps, a global cestode, encysts in the central nervous system (CNS) of sheep and other livestock. This frequently leads to their death and huge socioeconomic losses, especially in developing countries. This parasite can also cause zoonotic infections in humans, but has been largely neglected due to a lack of diagnostic techniques and studies. Recent developments in next-generation sequencing provide an opportunity to explore the transcriptome of T. multiceps. We obtained a total of 31,282 unigenes (mean length 920 bp) using Illumina paired-end sequencing technology and a new Trinity de novo assembler without a referenced genome. Individual transcription molecules were determined by sequence-based annotations and/or domain-based annotations against public databases (Nr, UniprotKB/Swiss-Prot, COG, KEGG, UniProtKB/TrEMBL, InterPro and Pfam). We identified 26,110 (83.47%) unigenes and inferred 20,896 (66.8%) coding sequences (CDS). Further comparative transcripts analysis with other cestodes (Taenia pisiformis, Taenia solium, Echincoccus granulosus and Echincoccus multilocularis) and intestinal parasites (Trichinella spiralis, Ancylostoma caninum and Ascaris suum) showed that 5,100 common genes were shared among three Taenia tapeworms, 261 conserved genes were detected among five Taeniidae cestodes, and 109 common genes were found in four zoonotic intestinal parasites. Some of the common genes were genes required for parasite survival, involved in parasite-host interactions. In addition, we amplified two full-length CDS of unigenes from the common genes using RT-PCR. This study provides an extensive transcriptome of the adult stage of T. multiceps, and demonstrates that comparative transcriptomic investigations deserve to be further studied. This transcriptome dataset forms a substantial public information platform to achieve a fundamental understanding of the biology of T. multiceps, and helps in the identification of drug targets and parasite-host interaction studies.

Genome and Transcriptome Sequencing of the Ostreid herpesvirus 1 From Tomales Bay, California

NASA Astrophysics Data System (ADS)

Burge, C. A.; Langevin, S.; Closek, C. J.; Roberts, S. B.; Friedman, C. S.

2016-02-01

Mass mortalities of larval and seed bivalve molluscs attributed to the Ostreid herpesvirus 1 (OsHV-1) occur globally. OsHV-1 was fully sequenced and characterized as a member of the Family Malacoherpesviridae. Multiple strains of OsHV-1 exist and may vary in virulence, i.e. OsHV-1 µvar. For most global variants of OsHV-1, sequence data is limited to PCR-based sequencing of segments, including two recent genomes. In the United States, OsHV-1 is limited to detection in adjacent embayments in California, Tomales and Drakes bays. Limited DNA sequence data of OsHV-1 infecting oysters in Tomales Bay indicates the virus detected in Tomales Bay is similar but not identical to any one global variant of OsHV-1. In order to better understand both strain variation and virulence of OsHV-1 infecting oysters in Tomales Bay, we used genomic and transcriptomic sequencing. Meta-genomic sequencing (Illumina MiSeq) was conducted from infected oysters (n=4 per year) collected in 2003, 2007, and 2014, where full OsHV-1 genome sequences and low overall microbial diversity were achieved from highly infected oysters. Increased microbial diversity was detected in three of four samples sequenced from 2003, where qPCR based genome copy numbers of OsHV-1 were lower. Expression analysis (SOLiD RNA sequencing) of OsHV-1 genes expressed in oyster larvae at 24 hours post exposure revealed a nearly complete transcriptome, with several highly expressed genes, which are similar to recent transcriptomic analyses of other OsHV-1 variants. Taken together, our results indicate that genome and transcriptome sequencing may be powerful tools in understanding both strain variation and virulence of non-culturable marine viruses.

Consequences of extreme life history traits on population persistence: do short-lived gobies face demographic bottlenecks?

NASA Astrophysics Data System (ADS)

Lefèvre, Carine D.; Nash, Kirsty L.; González-Cabello, Alonso; Bellwood, David R.

2016-06-01

The majority of coral reef goby species are short-lived, with some highly abundant species living less than 100 d. To understand the role and consequences of this extreme life history in shaping coral reef fish populations, we quantitatively documented the structure of small reef fish populations over a 26-month period (>14 short-lived fish generations) at an inshore reef on the Great Barrier Reef, Australia. Most species with life spans >1 yr, such as pomacentrids, exhibited a peak in recruitment during the austral summer, driving seasonal changes in the small fish community composition. In contrast, there were no clear changes in goby community composition, despite the abundance of short-lived, high turnover species. Species of Eviota, the most abundant gobiid genus observed, showed remarkably similar demographic profiles year-round, with consistent densities of adults as well as recently recruited juveniles. Our results demonstrate ongoing recruitment of these small cryptic fishes, which appears to compensate for an exceptionally short life span on the reef. Our results suggest that gobiid populations are able to overcome demographic limitations, and by maintaining reproduction, larval survival and recruitment throughout the year, they may avoid population bottlenecks. These findings also underline the potential trophodynamic importance of these small species; because of this constant turnover, Eviota species and other short-lived fishes may be particularly valuable contributors to the flow of energy on coral reefs, underpinning the year-round trophic structure.

Redefining metamorphosis in spiny lobsters: molecular analysis of the phyllosoma to puerulus transition in Sagmariasus verreauxi

PubMed Central

Ventura, Tomer; Fitzgibbon, Quinn P.; Battaglene, Stephen C.; Elizur, Abigail

2015-01-01

The molecular understanding of crustacean metamorphosis is hindered by small sized individuals and inability to accurately define molt stages. We used the spiny lobster Sagmariasus verreauxi where the large, transparent larvae enable accurate tracing of the transition from a leaf-shaped phyllosoma to an intermediate larval-juvenile phase (puerulus). Transcriptomic analysis of larvae at well-defined stages prior to, during, and following this transition show that the phyllosoma-puerulus metamorphic transition is accompanied by vast transcriptomic changes exceeding 25% of the transcriptome. Notably, genes previously identified as regulating metamorphosis in other crustaceans do not fluctuate during this transition but in the later, morphologically-subtle puerulus-juvenile transition, indicating that the dramatic phyllosoma-puerulus morphological shift relies on a different, yet to be identified metamorphic mechanism. We examined the change in expression of domains and gene families, with focus on several key genes. Our research implies that the separation in molecular triggering systems between the phyllosoma-puerulus and puerulus-juvenile transitions might have enabled the extension of the oceanic phase in spiny lobsters. Study of similar transitions, where metamorphosis is uncoupled from the transition into the benthic juvenile form, in other commercially important crustacean groups might show common features to point on the evolutionary advantage of this two staged regulation. PMID:26311524

Redefining metamorphosis in spiny lobsters: molecular analysis of the phyllosoma to puerulus transition in Sagmariasus verreauxi.

PubMed

Ventura, Tomer; Fitzgibbon, Quinn P; Battaglene, Stephen C; Elizur, Abigail

2015-08-27

The molecular understanding of crustacean metamorphosis is hindered by small sized individuals and inability to accurately define molt stages. We used the spiny lobster Sagmariasus verreauxi where the large, transparent larvae enable accurate tracing of the transition from a leaf-shaped phyllosoma to an intermediate larval-juvenile phase (puerulus). Transcriptomic analysis of larvae at well-defined stages prior to, during, and following this transition show that the phyllosoma-puerulus metamorphic transition is accompanied by vast transcriptomic changes exceeding 25% of the transcriptome. Notably, genes previously identified as regulating metamorphosis in other crustaceans do not fluctuate during this transition but in the later, morphologically-subtle puerulus-juvenile transition, indicating that the dramatic phyllosoma-puerulus morphological shift relies on a different, yet to be identified metamorphic mechanism. We examined the change in expression of domains and gene families, with focus on several key genes. Our research implies that the separation in molecular triggering systems between the phyllosoma-puerulus and puerulus-juvenile transitions might have enabled the extension of the oceanic phase in spiny lobsters. Study of similar transitions, where metamorphosis is uncoupled from the transition into the benthic juvenile form, in other commercially important crustacean groups might show common features to point on the evolutionary advantage of this two staged regulation.

Deciphering life history transcriptomes in different environments

PubMed Central

Etges, William J.; Trotter, Meredith V.; de Oliveira, Cássia C.; Rajpurohit, Subhash; Gibbs, Allen G.; Tuljapurkar, Shripad

2014-01-01

We compared whole transcriptome variation in six preadult stages and seven adult female ages in two populations of cactophilic Drosophila mojavensis reared on two host plants in order to understand how differences in gene expression influence standing life history variation. We used Singular Value Decomposition (SVD) to identify dominant trajectories of life cycle gene expression variation, performed pair-wise comparisons of stage and age differences in gene expression across the life cycle, identified when genes exhibited maximum levels of life cycle gene expression, and assessed population and host cactus effects on gene expression. Life cycle SVD analysis returned four significant components of transcriptional variation, revealing functional enrichment of genes responsible for growth, metabolic function, sensory perception, neural function, translation and aging. Host cactus effects on female gene expression revealed population and stage specific differences, including significant host plant effects on larval metabolism and development, as well as adult neurotransmitter binding and courtship behavior gene expression levels. In 3 - 6 day old virgin females, significant up-regulation of genes associated with meiosis and oogenesis was accompanied by down-regulation of genes associated with somatic maintenance, evidence for a life history tradeoff. The transcriptome of D. mojavensis reared in natural environments throughout its life cycle revealed core developmental transitions and genome wide influences on life history variation in natural populations. PMID:25442828

Snake venomics and venom gland transcriptomic analysis of Brazilian coral snakes, Micrurus altirostris and M. corallinus.

PubMed

Corrêa-Netto, Carlos; Junqueira-de-Azevedo, Inácio de L M; Silva, Débora A; Ho, Paulo L; Leitão-de-Araújo, Moema; Alves, Maria Lúcia M; Sanz, Libia; Foguel, Débora; Zingali, Russolina Benedeta; Calvete, Juan J

2011-08-24

The venom proteomes of Micrurus altirostris and M. corallinus were analyzed by combining snake venomics and venom gland transcriptomic surveys. In both coral snake species, 3FTx and PLA(2) were the most abundant and diversified toxin families. 33 different 3FTxs and 13 PLA(2) proteins, accounting respectively for 79.5% and 13.7% of the total proteins, were identified in the venom of M. altirostris. The venom of M. corallinus comprised 10 3FTx (81.7% of the venom proteome) and 4 (11.9%) PLA(2) molecules. Transcriptomic data provided the full-length amino acid sequences of 18 (M. altirostris) and 10 (M. corallinus) 3FTxs, and 3 (M. altirostris) and 1 (M. corallinus) novel PLA(2) sequences. In addition, venom from each species contained single members of minor toxin families: 3 common (PIII-SVMP, C-type lectin-like, L-amino acid oxidase) and 4 species-specific (CRISP, Kunitz-type inhibitor, lysosomal acid lipase in M. altirostris; serine proteinase in M. corallinus) toxin classes. The finding of a lipase (LIPA) in the venom proteome and in the venom gland transcriptome of M. altirostris supports the view of a recruitment event predating the divergence of Elapidae and Viperidae more than 60 Mya. The toxin profile of both M. altirostris and M. corallinus venoms points to 3FTxs and PLA(2) molecules as the major players of the envenoming process. In M. altirostris venom, all major, and most minor, 3FTxs display highest similarity to type I α-neurotoxins, suggesting that these postsynaptically acting toxins may play the predominant role in the neurotoxic effect leading to peripheral paralysis, respiratory arrest, and death. M. corallinus venom posesses both, type I α-neurotoxins and a high-abundance (26% of the venom proteome) protein of subfamily XIX of 3FTxs, exhibiting similarity to bucandin from Malayan krait, Bungarus candidus, venom, which enhances acetylcholine release presynaptically. This finding may explain the presynaptic neurotoxicity of M. corallinus venom and the lack of this effect in M. altirostris venom. The anti-Micrurus (corallinus and frontalis) antivenom produced by Instituto Butantan quantitatively immunodepleted the minor toxins from M. altirostris and M. corallinus venoms but showed impaired crossreactivity towards their major 3FTx and PLA(2) molecules. The structural diversity of 3FTxs among Micrurus sp. may underlay the impaired cross-immunoreactivity of the Butantan antivenom towards M. altirostris and M. corallinus toxins, hampering the possibility to raise an antivenom against a simple venom mixture exhibiting paraspecific neutralization of other Micrurus venoms. Copyright © 2011 Elsevier B.V. All rights reserved.

Transcriptome Profiling Identifies Multiplexin as a Target of SAGA Deubiquitinase Activity in Glia Required for Precise Axon Guidance During Drosophila Visual Development.

PubMed

Ma, Jingqun; Brennan, Kaelan J; D'Aloia, Mitch R; Pascuzzi, Pete E; Weake, Vikki M

2016-08-09

The Spt-Ada-Gcn5 Acetyltransferase (SAGA) complex is a transcriptional coactivator with histone acetylase and deubiquitinase activities that plays an important role in visual development and function. In Drosophila melanogaster, four SAGA subunits are required for the deubiquitination of monoubiquitinated histone H2B (ubH2B): Nonstop, Sgf11, E(y)2, and Ataxin 7. Mutations that disrupt SAGA deubiquitinase activity cause defects in neuronal connectivity in the developing Drosophila visual system. In addition, mutations in SAGA result in the human progressive visual disorder spinocerebellar ataxia type 7 (SCA7). Glial cells play a crucial role in both the neuronal connectivity defect in nonstop and sgf11 flies, and in the retinal degeneration observed in SCA7 patients. Thus, we sought to identify the gene targets of SAGA deubiquitinase activity in glia in the Drosophila larval central nervous system. To do this, we enriched glia from wild-type, nonstop, and sgf11 larval optic lobes using affinity-purification of KASH-GFP tagged nuclei, and then examined each transcriptome using RNA-seq. Our analysis showed that SAGA deubiquitinase activity is required for proper expression of 16% of actively transcribed genes in glia, especially genes involved in proteasome function, protein folding and axon guidance. We further show that the SAGA deubiquitinase-activated gene Multiplexin (Mp) is required in glia for proper photoreceptor axon targeting. Mutations in the human ortholog of Mp, COL18A1, have been identified in a family with a SCA7-like progressive visual disorder, suggesting that defects in the expression of this gene in SCA7 patients could play a role in the retinal degeneration that is unique to this ataxia. Copyright © 2016 Ma et al.

Transcriptome survey of the lipid metabolic pathways involved in energy production and ecdysteroid synthesis in the salmon louse Caligus rogercresseyi (Crustacea: Copepoda).

PubMed

Gonçalves, Ana Teresa; Farlora, Rodolfo; Gallardo-Escárate, Cristian

2014-10-01

The goal of this study was to identify and analyze the lipid metabolic pathways involved in energy production and ecdysteroid synthesis in the ectoparasite copepod Caligus rogercresseyi. Massive transcriptome sequencing analysis was performed during the infectious copepodid larval stage, during the attached chalimus larval stage, and also in female and male adults. Thirty genes were selected for describing the pathways, and these were annotated for proteins or enzymes involved in lipid digestion, absorption, and transport; fatty acid degradation; the synthesis and degradation of ketone bodies; and steroid and ecdysteroid syntheses. Differential expression of these genes was analyzed by ontogenic stage and discussed considering each stage's feeding habits and energetic needs. Copepodids showed a low expression of fatty acid digestion genes, reflected by a non-feeding behavior, and the upregulation of genes involved in steroid biosynthesis, which was consistent with a pathway for cholesterol synthesis during ecdysis. The chalimus stage showed an upregulation of genes related to fatty acid digestion, absorption, and transport, as well as to fatty acid degradation and the synthesis of ketone bodies, therefore suggesting that lipids ingested from the mucus and skin of the host fish are metabolized as important sources of energy. Adult females also showed a pattern of high lipid metabolism for energy supply and mobilization in relation to reproduction and vitellogenesis. Adult females and males revealed different lipid metabolism patterns that reflected different energetic needs. This study reports for the first time the probable lipid metabolic pathways involved in the energy production and ecdysteroid synthesis of C. rogercresseyi. Copyright © 2014 Elsevier Inc. All rights reserved.

Identification and Characterization of Candidate Chemosensory Gene Families from Spodoptera exigua Developmental Transcriptomes

PubMed Central

Liu, Nai-Yong; Zhang, Ting; Ye, Zhan-Feng; Li, Fei; Dong, Shuang-Lin

2015-01-01

Insect chemosensory genes have been considered as potential molecular targets to develop alternative strategies for pest control. However, in Spodoptera exigua, a seriously polyphagous agricultural pest, only a small part of such genes have been identified and characterized to date. Here, using a bioinformatics screen a total of 79 chemosensory genes were identified from a public transcriptomic data of different developmental stages (eggs, 1st to 5th instar larvae, pupae, female and male adults), including 34 odorant binding proteins (OBPs), 20 chemosensory proteins (CSPs), 22 chemosensory receptors (10 odorant receptors (ORs), six gustatory receptors (GRs) and six ionotropic receptors (IRs)) and three sensory neuron membrane proteins (SNMPs). Notably, a new group of lepidopteran SNMPs (SNMP3 group) was found for the first time in S. exigua, and confirmed in four other moth species. Further, reverse transcription PCR (RT-PCR) and quantitative real time PCR (qPCR) were employed respectively to validate the sequences and determine the expression patterns of 69 identified chemosensory genes regarding to sexes, tissues and stages. Results showed that 67 of these genes could be detected and reconstructed in at least one tissue tested. Further, 60 chemosensory genes were expressed in adult antennae and 52 in larval heads with the antennae, whereas over half of the genes were also detected in non-olfactory tissues like egg and thorax. Particularly, S. exigua OBP2 showed a predominantly larval head-biased expression, and functional studies further indicated its potentially olfactory roles in guiding food searching of larvae. This work suggests functional diversities of S. exigua chemosensory genes and could greatly facilitate the understanding of olfactory system in S. exigua and other lepidopteran species. PMID:26221071

Characterization of the Antarctic sea urchin (Sterechinus neumayeri) transcriptome and mitogenome: a molecular resource for phylogenetics, ecophysiology and global change biology.

PubMed

Dilly, G F; Gaitán-Espitia, J D; Hofmann, G E

2015-03-01

This is the first de novo transcriptome and complete mitochondrial genome of an Antarctic sea urchin species sequenced to date. Sterechinus neumayeri is an Antarctic sea urchin and a model species for ecology, development, physiology and global change biology. To identify transcripts important to ocean acidification (OA) and thermal stress, this transcriptome was created pooling, and 13 larval samples representing developmental stages on day 11 (late gastrula), 19 (early pluteus) and 30 (mid pluteus) maintained at three CO2 levels (421, 652, and 1071 μatm) as well as four additional heat-shocked samples. The normalized cDNA pool was sequenced using emulsion PCR (pyrosequencing) resulting in 1.34M reads with an average read length of 492 base pairs. 40,994 isotigs were identified, averaging 1188 bp with a median coverage of 11×. Additional primer design and gap sequencing were required to complete the mitochondrial genome. The mitogenome of S. neumayeri is a circular DNA molecule with a length of 15 684 bp that contains all 37 genes normally found in metazoans. We detail the main features of the transcriptome and the mitogenome architecture and investigate the phylogenetic relationships of S. neumayeri within Echinoidea. In addition, we provide comparative analyses of S. neumayeri with its closest relative, Strongylocentrotus purpuratus, including a list of potential OA gene targets. The resources described here will support a variety of quantitative (genomic, proteomic, multistress and comparative) studies to interrogate physiological responses to OA and other stressors in this important Antarctic calcifier. © 2014 John Wiley & Sons Ltd.

Connectivity of the South Florida Coral Reef Ecosystem to Upstream Waters of the Western Caribbean and Gulf of Mexico

NASA Astrophysics Data System (ADS)

Johns, E. M.; Smith, R. H.; Lamkin, J. T.; Birbriezca, L. C.; Vasquez-Yeomans, L.; Cordero, E. S.

2008-05-01

The coastal waters of south Florida, including the coral reefs of NOAA's Florida Keys National Marine Sanctuary (FKNMS), are directly connected by means of strong ocean currents with upstream waters of the western Caribbean Sea and the Gulf of Mexico. The Caribbean Current and the Loop Current provide a rapid conduit for transport from Mexican and Belizean coral reefs, located off the eastern shore of the Yucatan Peninsula, to nearshore regions of northern Cuba, Florida, and the Bahamas. Interdisciplinary cruise data collected in August 2002, March 2006 and January 2007 aboard the NOAA Ship Gordon Gunter, in combination with satellite-tracked surface drifter trajectories and remote sensing imagery, clearly show the highly variable and dynamic nature of the regional current regimes and provide a means of quantifying the potential pathways and transport rates of the coastal waters and their biological and chemical constituents from one region to another. Results from these cruises and ancillary data show that the study areas are connected with rapid transport time scales, and that frontal eddies and gyres play an important role in establishing the time and length scales of this connectivity. Such direct physical connectivity between the coral reef biota of these geographically separated spawning grounds via ocean currents may have an important influence on the degree of biological connectivity between regional larval populations. Initial analyses of ichthyoplankton surveys and inshore collections along the Yucatan mesoamerican reef suggest large scale variability in both local recruitment and large scale spatial distribution. Despite strong northward flowing currents, inshore collections indicate that local recruitment in some areas is strongly influenced by small scale circulation patterns. However, the distribution of spawning aggregations along the Yucatan coast suggests a larger role for the Caribbean Current. Determining the interactions between the larger scale circulation patterns and the smaller scale biological processes is a key research objective for understanding the observed regional population connections.

The Effect of Ambient Temperatures of Two Threatened Caribbean Coral Species: a Proteomic Study

NASA Astrophysics Data System (ADS)

Ricaurte, M.; Schizas, N. V.; Weil, E.; Ciborowski, P.; Boukli, N. M.

2016-02-01

Coral reefs are among the most valuable ecosystems on the earth. Increasing water temperatures as a consequence of global warming have been identified, as an overriding cause of coral decline (e.g. increased incidence of diseases, bleaching), and one of the regions that has been identified vulnerable to climatic changes, is the Caribbean. Laboratory experiments have shown negative effects of different temperatures in coral growth, larval and adult survival, and gene expression. In order to understand the molecular and cellular basis in the protein regulation during changes in temperature in the field, a comparative proteomic analysis associated with thermal fluctuations was made from wet and dry season of 2014. In the study, we investigated alterations in proteins of Acropora palmata and Orbicella faveolata by two-dimensional gel electrophoresis (2D-GE) followed by liquid chromatography-tandem mass spectrometry, protein identification, and confirmation at the gene expression level by qRT-PCR.Proteomes of related samples demonstrated 195 differentially expressed proteins (DEP) in A. palmata during dry season and 108 (DEP) during wet season of 2014. O. faveolata overexpressed 62 (DEP) in dry season and 190 (DEP) during wet season of 2014. All proteins had a two-fold or greater change in expression due to temperature, altering several components of the cellular stress response that include chaperones, stress proteins, antioxidant enzymes, proteases, cytoskeletal and apoptosis regulating proteins. Our results suggest that A. palmata and O. faveolata display a distinct response by expressing these key protein signatures in dry and wet season. This proteomic approach may open new avenues of research to detect potential early biomarkers involved in response to these stressors, during seasonal changes in water temperatures. The results provide insight into targets and mechanistic strategies to detect potential markers involved in response to temperature change for A. palmata and O. faveolata during seasonal changes in water temperatures.

Population Genetics of an Ecosystem-Defining Reef Coral Pocillopora damicornis in the Tropical Eastern Pacific

PubMed Central

Combosch, David J.; Vollmer, Steven V.

2011-01-01

Background Coral reefs in the Tropical Eastern Pacific (TEP) are amongst the most peripheral and geographically isolated in the world. This isolation has shaped the biology of TEP organisms and lead to the formation of numerous endemic species. For example, the coral Pocillopora damicornis is a minor reef-builder elsewhere in the Indo-West Pacific, but is the dominant reef-building coral in the TEP, where it forms large, mono-specific stands, covering many hectares of reef. Moreover, TEP P. damicornis reproduces by broadcast spawning, while it broods mostly parthenogenetic larvae throughout the rest of the Indo-West Pacific. Population genetic surveys for P. damicornis from across its Indo-Pacific range indicate that gene flow (i.e. larval dispersal) is generally limited over hundreds of kilometers or less. Little is known about the population genetic structure and the dispersal potential of P. damicornis in the TEP. Methodology Using multilocus microsatellite data, we analyzed the population structure of TEP P. damicornis among and within nine reefs and test for significant genetic structure across three geographically and ecologically distinct regions in Panama. Principal Findings/Conclusions We detected significant levels of population genetic structure (global RST = 0.162), indicating restricted gene flow (i.e. larvae dispersal), both among the three regions (RRT = 0.081) as well as within regions (RSR = 0.089). Limited gene flow across a distinct environmental cline, like the regional upwelling gradient in Panama, indicates a significant potential for differential adaptation and population differentiation. Individual reefs were characterized by unexpectedly high genet diversity (avg. 94%), relatively high inbreeding coefficients (global FIS = 0.183), and localized spatial genetic structure among individuals (i.e. unique genets) over 10 m intervals. These findings suggest that gene flow is limited in TEP P. damicornis populations, particularly among regions, but even over meter scales within populations. PMID:21857900

Long prereproductive selection and divergence by depth in a Caribbean candelabrum coral

PubMed Central

Prada, Carlos; Hellberg, Michael E.

2013-01-01

Long-lived corals, the foundation of modern reefs, often follow ecological gradients, so that populations or sister species segregate by habitat. Adaptive divergence maintains sympatric congeners after secondary contact or may even generate species by natural selection in the face of gene flow. Such ecological divergence, initially between alternative phenotypes within populations, may be aided by immigrant inviability, especially when a long period separates larval dispersal and the onset of reproduction, during which selection can sort lineages to match different habitats. Here, we evaluate the strength of one ecological factor (depth) to isolate populations by comparing the genes and morphologies of pairs of depth-segregated populations of the candelabrum coral Eunicea flexuosa across the Caribbean. Eunicea is endemic to the Caribbean and all sister species co-occur. Eunicea flexuosa is widespread both geographically and across reef habitats. Our genetic analysis revealed two depth-segregated lineages. Field survivorship data, combined with estimates of selection coefficients based on transplant experiments, suggest that selection is strong enough to segregate these two lineages. Genetic exchange between the Shallow and Deep lineages occurred either immediately after divergence or the two have diverged with gene flow. Migration occurs asymmetrically from the Shallow to Deep lineage. Limited recruitment to reproductive age, even under weak annual selection advantage, is sufficient to generate habitat segregation because of the cumulative prolonged prereproductive selection. Ecological factors associated with depth can act as filters generating strong barriers to gene flow, altering morphologies, and contributing to the potential for speciation in the sea. PMID:23359716

Phenology of sexual reproduction in the common coral reef sponge, Carteriospongia foliascens

NASA Astrophysics Data System (ADS)

Abdul Wahab, M. A.; de Nys, R.; Webster, N.; Whalan, S.

2014-06-01

Understanding processes that contribute to population maintenance is critical to the management and conservation of species. Despite this, very little is currently known about the reproductive biology of Great Barrier Reef (GBR) sponge species. Here, we established reproductive parameters including mode of sexuality and development, seasonality, sex ratios, gametogenesis, reproductive output, and size at sexual maturity for the common phototrophic intertidal sponge, Carteriospongia foliascens, in the central GBR over two reproductive cycles. A population sexual productivity index (PoSPi) integrating key reproductive parameters was formulated to compare population larval supply over time. This study shows that C. foliascens is reproductive all year round, gonochoric and viviparous, with larvae developing asynchronously throughout the mesohyl. The influence of environmental parameters relevant to C. foliascens reproduction [i.e., sea surface temperature (SST), photoperiod, and rainfall] was also examined, and SST was found to have the most significant effect on phenology. C. foliascens reproduction exhibited annual mono-cyclic patterns closely resembling SST fluctuations. Reproductive output was depressed at low SST (<23 °C) and increased at temperatures above 23 °C. Peak sperm release occurred at temperatures above 25 °C, while peak larval release occurred during the annual temperature maxima (>28 °C). A twofold increase in maximum larval production (PoSPi) in C. foliascens was observed in the second reproductive cycle, following a depressed PoSPi in the first cycle. This reduction in PoSPi in the first reproductive cycle was associated with elevated SST and rainfall, coinciding with one of the strongest La Niña events on record.

Global Transcriptome Sequencing Reveals Molecular Profiles of Summer Diapause Induction Stage of Onion Maggot, Delia antiqua (Diptera: Anthomyiidae)

PubMed Central

Ren, Shuang; Hao, You-Jin; Chen, Bin; Yin, You-Ping

2017-01-01

The onion maggot, Delia antiqua, is a worldwide subterranean pest and can enter diapause during the summer and winter seasons. The molecular regulation of the ontogenesis transition remains largely unknown. Here we used high-throughput RNA sequencing to identify candidate genes and processes linked to summer diapause (SD) induction by comparing the transcriptome differences between the most sensitive larval developmental stage of SD and nondiapause (ND). Nine pairwise comparisons were performed, and significantly differentially regulated transcripts were identified. Several functional terms related to lipid, carbohydrate, and energy metabolism, environmental adaption, immune response, and aging were enriched during the most sensitive SD induction period. A subset of genes, including circadian clock genes, were expressed differentially under diapause induction conditions, and there was much more variation in the most sensitive period of ND- than SD-destined larvae. These expression variations probably resulted in a deep restructuring of metabolic pathways. Potential regulatory elements of SD induction including genes related to lipid, carbohydrate, energy metabolism, and environmental adaption. Collectively, our results suggest the circadian clock is one of the key drivers for integrating environmental signals into the SD induction. Our transcriptome analysis provides insight into the fundamental role of the circadian clock in SD induction in this important model insect species, and contributes to the in-depth elucidation of the molecular regulation mechanism of insect diapause induction. PMID:29158334

The Transcriptome Analysis of Strongyloides stercoralis L3i Larvae Reveals Targets for Intervention in a Neglected Disease

PubMed Central

Marcilla, Antonio; Garg, Gagan; Bernal, Dolores; Ranganathan, Shoba; Forment, Javier; Ortiz, Javier; Muñoz-Antolí, Carla; Dominguez, M. Victoria; Pedrola, Laia; Martinez-Blanch, Juan; Sotillo, Javier; Trelis, Maria; Toledo, Rafael; Esteban, J. Guillermo

2012-01-01

Background Strongyloidiasis is one of the most neglected diseases distributed worldwide with endemic areas in developed countries, where chronic infections are life threatening. Despite its impact, very little is known about the molecular biology of the parasite involved and its interplay with its hosts. Next generation sequencing technologies now provide unique opportunities to rapidly address these questions. Principal Findings Here we present the first transcriptome of the third larval stage of S. stercoralis using 454 sequencing coupled with semi-automated bioinformatic analyses. 253,266 raw sequence reads were assembled into 11,250 contiguous sequences, most of which were novel. 8037 putative proteins were characterized based on homology, gene ontology and/or biochemical pathways. Comparison of the transcriptome of S. strongyloides with those of other nematodes, including S. ratti, revealed similarities in transcription of molecules inferred to have key roles in parasite-host interactions. Enzymatic proteins, like kinases and proteases, were abundant. 1213 putative excretory/secretory proteins were compiled using a new pipeline which included non-classical secretory proteins. Potential drug targets were also identified. Conclusions Overall, the present dataset should provide a solid foundation for future fundamental genomic, proteomic and metabolomic explorations of S. stercoralis, as well as a basis for applied outcomes, such as the development of novel methods of intervention against this neglected parasite. PMID:22389732

Analysis of gene expression in the midgut of Bombyx mori during the larval molting stage.

PubMed

Yang, Bing; Huang, Wuren; Zhang, Jie; Xu, Qiuyun; Zhu, Shoulin; Zhang, Qiaoli; Beerntsen, Brenda T; Song, Hongsheng; Ling, Erjun

2016-11-03

Insects can be models for understanding human intestinal infection and pathology. Molting, a special period during which the old insect cuticle is shed and a new one is produced, is crucial for insect development. Holometabolous insects may experience several larva-to-larva moltings to become larger, a pupal molt and adult eclosion to become adults. During the larval molts, they stop feeding and become quiescent. Although the molting larvae become quiescent, it is not known if changes in microbiome, physiology, development and immunity of midguts occur. Transcriptome analysis indicated that functions such as metabolism, digestion, and transport may become reduced due to the downregulated expression of many associated genes. During the molting stage, midguts harbor less microflora and DNA synthesis decreases. Both ecdysone and juvenile hormone in the larval midgut likely degrade after entering the larva-to-larva molting stage. However, at 12 h after ecdysis, the feeding larvae of 5th instars that were injected with 20-hydroxyecdysone entered a molting-like stage, during which changes in midgut morphology, DNA synthesis, gene expression, and microflora exhibited the same patterns as observed in the actual molting state. This study is important for understanding insect midgut physiology, development and immunity during a special development stage when no food is ingested. Although the molting larva becomes immobile and quiescent, we demonstrate that numerous changes occur in midgut morphology, physiology, metabolism and microbiome during this period.

Detailed Transcriptome Description of the Neglected Cestode Taenia multiceps

PubMed Central

Wu, Xuhang; Fu, Yan; Yang, Deying; Zhang, Runhui; Zheng, Wanpeng; Nie, Huaming; Xie, Yue; Yan, Ning; Hao, Guiying; Gu, Xiaobin; Wang, Shuxian; Peng, Xuerong; Yang, Guangyou

2012-01-01

Background The larval stage of Taenia multiceps, a global cestode, encysts in the central nervous system (CNS) of sheep and other livestock. This frequently leads to their death and huge socioeconomic losses, especially in developing countries. This parasite can also cause zoonotic infections in humans, but has been largely neglected due to a lack of diagnostic techniques and studies. Recent developments in next-generation sequencing provide an opportunity to explore the transcriptome of T. multiceps. Methodology/Principal Findings We obtained a total of 31,282 unigenes (mean length 920 bp) using Illumina paired-end sequencing technology and a new Trinity de novo assembler without a referenced genome. Individual transcription molecules were determined by sequence-based annotations and/or domain-based annotations against public databases (Nr, UniprotKB/Swiss-Prot, COG, KEGG, UniProtKB/TrEMBL, InterPro and Pfam). We identified 26,110 (83.47%) unigenes and inferred 20,896 (66.8%) coding sequences (CDS). Further comparative transcripts analysis with other cestodes (Taenia pisiformis, Taenia solium, Echincoccus granulosus and Echincoccus multilocularis) and intestinal parasites (Trichinella spiralis, Ancylostoma caninum and Ascaris suum) showed that 5,100 common genes were shared among three Taenia tapeworms, 261 conserved genes were detected among five Taeniidae cestodes, and 109 common genes were found in four zoonotic intestinal parasites. Some of the common genes were genes required for parasite survival, involved in parasite-host interactions. In addition, we amplified two full-length CDS of unigenes from the common genes using RT-PCR. Conclusions/Significance This study provides an extensive transcriptome of the adult stage of T. multiceps, and demonstrates that comparative transcriptomic investigations deserve to be further studied. This transcriptome dataset forms a substantial public information platform to achieve a fundamental understanding of the biology of T. multiceps, and helps in the identification of drug targets and parasite-host interaction studies. PMID:23049872

Seasonal changes in the larvel populations of Aedes aegypti in two biotopes in Dar es Salaam, Tanzania

PubMed Central

Trpis, Milan

1972-01-01

The seasonal dynamics of larval populations of Aedes aegypti was studied in two different biotopes in Dar es Salaam, Tanzania. The first biotope was located on the Msasani peninsula on the coast 6 km north of Dar es Salaam, where A. aegypti breeds exclusively in coral rock holes. The population dynamics was studied during both the rainy and the dry season. Seasonal changes in the density of A. aegypti larvae depend primarily on variation in rainfall. The population of larvae dropped to zero only for a short time during the driest period while the adult population was maintained at a low level. The second biotope was in an automobile dump in a Dar es Salaam suburb, where A. aegypti breeds in artificial containers such as tires, automobile parts, tins, coconut shells, and snail shells. The greater part of the A. aegypti population of this biotope is maintained in the egg stage during the dry season. It serves as a focal point for breeding during the dry season: with the coming of the rains, the population expands into the surrounding residential areas. More than 70% of the larval population developed in tires, 20% in tins, 5% in coconut shells, and 1% in snail shells. PMID:4539415

Calcifying algae maintain settlement cues to larval abalone following algal exposure to extreme ocean acidification.

PubMed

O'Leary, Jennifer K; Barry, James P; Gabrielson, Paul W; Rogers-Bennett, Laura; Potts, Donald C; Palumbi, Stephen R; Micheli, Fiorenza

2017-07-18

Ocean acidification (OA) increasingly threatens marine systems, and is especially harmful to calcifying organisms. One important question is whether OA will alter species interactions. Crustose coralline algae (CCA) provide space and chemical cues for larval settlement. CCA have shown strongly negative responses to OA in previous studies, including disruption of settlement cues to corals. In California, CCA provide cues for seven species of harvested, threatened, and endangered abalone. We exposed four common CCA genera and a crustose calcifying red algae, Peyssonnelia (collectively CCRA) from California to three pCO 2 levels ranging from 419-2,013 µatm for four months. We then evaluated abalone (Haliotis rufescens) settlement under ambient conditions among the CCRA and non-algal controls that had been previously exposed to the pCO 2 treatments. Abalone settlement and metamorphosis increased from 11% in the absence of CCRA to 45-69% when CCRA were present, with minor variation among CCRA genera. Though all CCRA genera reduced growth during exposure to increased pCO 2 , abalone settlement was unaffected by prior CCRA exposure to increased pCO 2 . Thus, we find no impacts of OA exposure history on CCRA provision of settlement cues. Additionally, there appears to be functional redundancy in genera of CCRA providing cues to abalone, which may further buffer OA effects.

Near-future carbon dioxide levels alter fish behaviour by interfering with neurotransmitter function

NASA Astrophysics Data System (ADS)

Nilsson, Göran E.; Dixson, Danielle L.; Domenici, Paolo; McCormick, Mark I.; Sørensen, Christina; Watson, Sue-Ann; Munday, Philip L.

2012-03-01

Predicted future CO2 levels have been found to alter sensory responses and behaviour of marine fishes. Changes include increased boldness and activity, loss of behavioural lateralization, altered auditory preferences and impaired olfactory function. Impaired olfactory function makes larval fish attracted to odours they normally avoid, including ones from predators and unfavourable habitats. These behavioural alterations have significant effects on mortality that may have far-reaching implications for population replenishment, community structure and ecosystem function. However, the underlying mechanism linking high CO2 to these diverse responses has been unknown. Here we show that abnormal olfactory preferences and loss of behavioural lateralization exhibited by two species of larval coral reef fish exposed to high CO2 can be rapidly and effectively reversed by treatment with an antagonist of the GABA-A receptor. GABA-A is a major neurotransmitter receptor in the vertebrate brain. Thus, our results indicate that high CO2 interferes with neurotransmitter function, a hitherto unrecognized threat to marine populations and ecosystems. Given the ubiquity and conserved function of GABA-A receptors, we predict that rising CO2 levels could cause sensory and behavioural impairment in a wide range of marine species, especially those that tightly control their acid-base balance through regulatory changes in HCO3- and Cl- levels.

Exposure of clownfish larvae to suspended sediment levels found on the Great Barrier Reef: Impacts on gill structure and microbiome

PubMed Central

Hess, Sybille; Wenger, Amelia S.; Ainsworth, Tracy D.; Rummer, Jodie L.

2015-01-01

Worldwide, increasing coastal development has played a major role in shaping coral reef species assemblages, but the mechanisms underpinning distribution patterns remain poorly understood. Recent research demonstrated delayed development in larval fishes exposed to suspended sediment, highlighting the need to further understand the interaction between suspended sediment as a stressor and energetically costly activities such as growth and development that are essential to support biological fitness. We examined the gill morphology and the gill microbiome in clownfish larvae (Amphiprion percula) exposed to suspended sediment concentrations (using Australian bentonite) commonly found on the inshore Great Barrier Reef. The gills of larvae exposed to 45 mg L−1 of suspended sediment had excessive mucous discharge and growth of protective cell layers, resulting in a 56% thicker gill epithelium compared to fish from the control group. Further, we found a shift from ‘healthy’ to pathogenic bacterial communities on the gills, which could increase the disease susceptibility of larvae. The impact of suspended sediments on larval gills may represent an underlying mechanism behind the distribution patterns of fish assemblages. Our findings underscore the necessity for future coastal development to consider adverse effects of suspended sediments on fish recruitment, and consequently fish populations and ecosystem health. PMID:26094624

Exposure of clownfish larvae to suspended sediment levels found on the Great Barrier Reef: Impacts on gill structure and microbiome.

PubMed

Hess, Sybille; Wenger, Amelia S; Ainsworth, Tracy D; Rummer, Jodie L

2015-06-22

Worldwide, increasing coastal development has played a major role in shaping coral reef species assemblages, but the mechanisms underpinning distribution patterns remain poorly understood. Recent research demonstrated delayed development in larval fishes exposed to suspended sediment, highlighting the need to further understand the interaction between suspended sediment as a stressor and energetically costly activities such as growth and development that are essential to support biological fitness. We examined the gill morphology and the gill microbiome in clownfish larvae (Amphiprion percula) exposed to suspended sediment concentrations (using Australian bentonite) commonly found on the inshore Great Barrier Reef. The gills of larvae exposed to 45 mg L(-1) of suspended sediment had excessive mucous discharge and growth of protective cell layers, resulting in a 56% thicker gill epithelium compared to fish from the control group. Further, we found a shift from 'healthy' to pathogenic bacterial communities on the gills, which could increase the disease susceptibility of larvae. The impact of suspended sediments on larval gills may represent an underlying mechanism behind the distribution patterns of fish assemblages. Our findings underscore the necessity for future coastal development to consider adverse effects of suspended sediments on fish recruitment, and consequently fish populations and ecosystem health.

Spatiotemporal Variability of Dimethylsulphoniopropionate on a Fringing Coral Reef: The Role of Reefal Carbonate Chemistry and Environmental Variability

PubMed Central

Burdett, Heidi L.; Donohue, Penelope J. C.; Hatton, Angela D.; Alwany, Magdy A.; Kamenos, Nicholas A.

2013-01-01

Oceanic pH is projected to decrease by up to 0.5 units by 2100 (a process known as ocean acidification, OA), reducing the calcium carbonate saturation state of the oceans. The coastal ocean is expected to experience periods of even lower carbonate saturation state because of the inherent natural variability of coastal habitats. Thus, in order to accurately project the impact of OA on the coastal ocean, we must first understand its natural variability. The production of dimethylsulphoniopropionate (DMSP) by marine algae and the release of DMSP’s breakdown product dimethylsulphide (DMS) are often related to environmental stress. This study investigated the spatiotemporal response of tropical macroalgae (Padina sp., Amphiroa sp. and Turbinaria sp.) and the overlying water column to natural changes in reefal carbonate chemistry. We compared macroalgal intracellular DMSP and water column DMSP+DMS concentrations between the environmentally stable reef crest and environmentally variable reef flat of the fringing Suleman Reef, Egypt, over 45-hour sampling periods. Similar diel patterns were observed throughout: maximum intracellular DMSP and water column DMS/P concentrations were observed at night, coinciding with the time of lowest carbonate saturation state. Spatially, water column DMS/P concentrations were highest over areas dominated by seagrass and macroalgae (dissolved DMS/P) and phytoplankton (particulate DMS/P) rather than corals. This research suggests that macroalgae may use DMSP to maintain metabolic function during periods of low carbonate saturation state. In the reef system, seagrass and macroalgae may be more important benthic producers of dissolved DMS/P than corals. An increase in DMS/P concentrations during periods of low carbonate saturation state may become ecologically important in the future under an OA regime, impacting larval settlement and increasing atmospheric emissions of DMS. PMID:23724073

Characteristics of Settling Coral Reef Fish Are Related to Recruitment Timing and Success

PubMed Central

Rankin, Tauna L.; Sponaugle, Su

2014-01-01

Many marine populations exhibit high variability in the recruitment of young into the population. While environmental cycles and oceanography explain some patterns of replenishment, the role of other growth-related processes in influencing settlement and recruitment is less clear. Examination of a 65-mo. time series of recruitment of a common coral reef fish, Stegastes partitus, to the reefs of the upper Florida Keys revealed that during peak recruitment months, settlement stage larvae arriving during dark lunar phases grew faster as larvae and were larger at settlement compared to those settling during the light lunar phases. However, the strength and direction of early trait-mediated selective mortality also varied by settlement lunar phase such that the early life history traits of 2–4 week old recruit survivors that settled across the lunar cycle converged to more similar values. Similarly, within peak settlement periods, early life history traits of settling larvae and selective mortality of recruits varied by the magnitude of the settlement event: larvae settling in larger events had longer PLDs and consequently were larger at settlement than those settling in smaller pulses. Traits also varied by recruitment habitat: recruits surviving in live coral habitat (vs rubble) or areas with higher densities of adult conspecifics were those that were larger at settlement. Reef habitats, especially those with high densities of territorial conspecifics, are more challenging habitats for young fish to occupy and small settlers (due to lower larval growth and/or shorter PLDs) to these habitats have a lower chance of survival than they do in rubble habitats. Settling reef fish are not all equal and the time and location of settlement influences the likelihood that individuals will survive to contribute to the population. PMID:25250964

Mosquito control pesticides and sea surface temperatures have differential effects on the survival and oxidative stress response of coral larvae.

PubMed

Ross, Cliff; Olsen, Kevin; Henry, Michael; Pierce, Richard

2015-04-01

The declining health of coral reefs is intensifying worldwide at an alarming rate due to the combined effects of land-based sources of pollution and climate change. Despite the persistent use of mosquito control pesticides in populated coastal areas, studies examining the survival and physiological impacts of early life-history stages of non-targeted marine organisms are limited. In order to better understand the combined effects of mosquito pesticides and rising sea surface temperatures, we exposed larvae from the coral Porites astreoides to selected concentrations of two major mosquito pesticide ingredients, naled and permethrin, and seawater elevated +3.5 °C. Following 18-20 h of exposure, larvae exposed to naled concentrations of 2.96 µg L(-1) or greater had significantly reduced survivorship compared to controls. These effects were not detected in the presence of permethrin or elevated temperature. Furthermore, larval settlement, post-settlement survival and zooxanthellae density were not impacted by any treatment. To evaluate the sub-lethal stress response of larvae, several oxidative stress endpoints were utilized. Biomarker responses to pesticide exposure were variable and contingent upon pesticide type as well as the specific biomarker being employed. In some cases, such as with protein carbonylation and catalase gene expression, the effects of naled exposure and temperature were interactive. In other cases pesticide exposure failed to induce any sub-lethal stress response. Overall, these results demonstrate that P. astreoides larvae have a moderate degree of resistance against short-term exposure to ecologically relevant concentrations of pesticides even in the presence of elevated temperature. In addition, this work highlights the importance of considering the complexity and differential responses encountered when examining the impacts of combined stressors that occur on varying spatial scales.

Life history, larval dispersal, and connectivity in coral reef fish among the Scattered Islands of the Mozambique Channel

NASA Astrophysics Data System (ADS)

O'Donnell, James L.; Beldade, Ricardo; Mills, Suzanne C.; Williams, Hannah E.; Bernardi, Giacomo

2017-03-01

The Western Indian Ocean harbors one of the world's most diverse marine biota yet is threatened by exploitation with few conservation measures in place. Primary candidates for conservation in the region are the Scattered Islands (Îles Éparses), a group of relatively pristine and uninhabited islands in the Mozambique Channel. However, while optimal conservation strategies depend on the degree of population connectivity among spatially isolated habitats, very few studies have been conducted in the area. Here, we use highly variable microsatellite markers from two damselfishes ( Amphiprion akallopisos and Dascyllus trimaculatus) with differing life history traits [pelagic larval duration (PLD), adult habitat] to compare genetic structure and connectivity among these islands using classic population structure indices as well as Bayesian clustering methods. All classical fixation indexes F ST, R ST, G'ST, and Jost's D show stronger genetic differentiation among islands for A. akallopisos compared to D. trimaculatus, consistent with the former species' shorter PLD and stronger adult site attachment, which may restrict larval dispersal potential. In agreement with these results, the Bayesian analysis revealed clear genetic differentiation among the islands in A. akallopisos, separating the southern group (Bassas da India and Europa) from the center (Juan de Nova) and northern (Îles Glorieuses) islands, but not for D. trimaculatus. Local oceanographic patterns such as eddies that occur along the Mozambique Channel appear to parallel the results reported for A. akallopisos, but such features seem to have little effect on the genetic differentiation of D. trimaculatus. The contrasting patterns of genetic differentiation between species within the same family highlight the importance of accounting for diverse life history traits when assessing community-wide connectivity, an increasingly common consideration in conservation planning.

Molecular cloning and characterization of a steroidogenic enzyme, 17β-hydroxysteroid dehydrogenase type 14, from the stony coral Euphyllia ancora (Cnidaria, Anthozoa).

PubMed

Shikina, Shinya; Chung, Yi-Jou; Chiu, Yi-Ling; Huang, Yi-Jie; Lee, Yan-Horn; Chang, Ching-Fong

2016-03-01

Sex steroids play a fundamental role not only in reproduction but also in various other biological processes in vertebrates. Although the presence of sex steroids has been confirmed in cnidarians (e.g., coral, sea anemone, jellyfish, and hydra), which are basal metazoans, only a few studies to date have characterized steroidogenesis-related genes in cnidarians. Based on a transcriptomic analysis of the stony coral Euphyllia ancora, we identified the steroidogenic enzyme 17β-hydroxysteroid dehydrogenase type 14 (17beta-hsd 14), an oxidative enzyme that catalyzes the NAD(+)-dependent inactivation of estrogen/androgen (estradiol to estrone and testosterone to androstenedione) in mammals. Phylogenetic analysis showed that E. ancora 17beta-Hsd 14 (Ea17beta-Hsd 14) clusters with other animal 17beta-HSD 14s but not with other members of the 17beta-HSD family. Subsequent quantitative RT-PCR analysis revealed a lack of correlation of Ea17beta-hsd 14 transcript levels with the coral's reproductive cycle. In addition, Ea17beta-hsd 14 transcript and protein were detected in all tissues examined, such as the tentacles, mesenterial filaments, and gonads, at similar levels in both sexes, as determined by quantitative RT-PCR analysis and Western blotting with an anti-Ea17beta-Hsd 14 antibody. Immunohistochemical analysis revealed that Ea17beta-Hsd 14 is mainly distributed in the endodermal regions of the polyps, but the protein was also observed in all tissues examined. These results suggest that Ea17beta-Hsd 14 is involved in important functions that commonly occur in endodermal cells or has multiple functions in different tissues. Our data provide information for comparison with advanced animals as well as insight into the evolution of steroidogenesis-related genes in metazoans. Copyright © 2016 Elsevier Inc. All rights reserved.

The transcriptome of Spodoptera exigua larvae exposed to different types of microbes.

PubMed

Pascual, Laura; Jakubowska, Agata K; Blanca, Jose M; Cañizares, Joaquin; Ferré, Juan; Gloeckner, Gernot; Vogel, Heiko; Herrero, Salvador

2012-08-01

We have obtained and characterized the transcriptome of Spodoptera exigua larvae with special emphasis on pathogen-induced genes. In order to obtain a highly representative transcriptome, we have pooled RNA from diverse insect colonies, conditions and tissues. Sequenced cDNA included samples from 3 geographically different colonies. Enrichment of RNA from pathogen-related genes was accomplished by exposing larvae to different pathogenic and non-pathogenic microbial agents such as the bacteria Bacillus thuringiensis, Micrococcus luteus, and Escherichia coli, the yeast Saccharomyces cerevisiae, and the S. exigua nucleopolyhedrovirus (SeMNPV). In addition, to avoid the loss of tissue-specific genes we included cDNA from the midgut, fat body, hemocytes and integument derived from pathogen exposed insects. RNA obtained from the different types of samples was pooled, normalized and sequenced. Analysis of the sequences obtained using the Roche 454 FLX and Sanger methods has allowed the generation of the largest public set of ESTs from S. exigua, including a large group of immune genes, and the identification of an important number of SSR (simple sequence repeats) and SNVs (single nucleotide variants: SNPs and INDELs) with potential use as genetic markers. Moreover, data mining has allowed the discovery of novel RNA viruses with potential influence in the insect population dynamics and the larval interactions with the microbial pesticides that are currently in use for the biological control of this pest. Copyright © 2012 Elsevier Ltd. All rights reserved.

Comparative transcriptome analysis on the alteration of gene expression in ayu (Plecoglossus altivelis) larvae associated with salinity change.

PubMed

Lu, Xin-Jiang; Zhang, Hao; Yang, Guan-Jun; Li, Ming-Yun; Chen, Jiong

2016-05-18

Ayu (Plecoglossus altivelis) fish, which are an amphidromous species distributed in East Asia, live in brackish water (BW) during their larval stage and in fresh water (FW) during their adult stage. In this study, we found that FW-acclimated ayu larvae exhibited a slower growth ratio compared with that of BW-acclimated larvae. However, the mechanism underlying FW acclimation on growth suppression is poorly known. We employed transcriptome analysis to investigate the differential gene expression of FW acclimation by RNA sequencing. We identified 158 upregulated and 139 downregulated transcripts in FW-acclimated ayu larvae compared with that in BW-acclimated larvae. As determined by Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway mapping, functional annotation of the genes covered diverse biological functions and processes, and included neuroendocrinology, osmotic regulation, energy metabolism, and the cytoskeleton. Transcriptional expression of several differentially expressed genes in response to FW acclimation was further confirmed by real-time quantitative PCR. In accordance with transcriptome analysis, iodothyronine deiodinase (ID), pro-opiomelanocortin (POMC), betaine-homocysteine S-methyltransferase 1(BHMT), fructose-bisphosphate aldolase B (aldolase B), tyrosine aminotransferase (TAT), and Na(+)-K(+) ATPase (NKA) were upregulated after FW acclimation. Furthermore, the mRNA expressions of b-type natriuretic peptide (BNP) and transgelin were downregulated after FW acclimation. Our data indicate that FW acclimation reduced the growth rate of ayu larvae, which might result from the expression alteration of genes related to endocrine hormones, energy metabolism, and direct osmoregulation.

RNA-Seq Comparison of Larval and Adult Malpighian Tubules of the Yellow Fever Mosquito Aedes aegypti Reveals Life Stage-Specific Changes in Renal Function.

PubMed

Li, Yiyi; Piermarini, Peter M; Esquivel, Carlos J; Drumm, Hannah E; Schilkey, Faye D; Hansen, Immo A

2017-01-01

Introduction: The life history of Aedes aegypti presents diverse challenges to its diuretic system. During the larval and pupal life stages mosquitoes are aquatic. With the emergence of the adult they become terrestrial. This shifts the organism within minutes from an aquatic environment to a terrestrial environment where dehydration has to be avoided. In addition, female mosquitoes take large blood meals, which present an entirely new set of challenges to salt and water homeostasis. Methods: To determine differences in gene expression associated with these different life stages, we performed an RNA-seq analysis of the main diuretic tissue in A. aegypti , the Malpighian tubules. We compared transcript abundance in 4th instar larvae to that of adult females and analyzed the data with a focus on transcripts that encode proteins potentially involved in diuresis, like water and solute channels as well as ion transporters. We compared our results against the model of potassium- and sodium chloride excretion in the Malpighian tubules proposed by Hine et al. (2014), which involves at least eight ion transporters and a proton-pump. Results: We found 3,421 of a total number of 17,478 (19.6%) unique transcripts with a P < 0.05 and at least a 2.5 fold change in expression levels between the two groups. We identified two novel transporter genes that are highly expressed in the adult Malpighian tubules, which have not previously been part of the transport model in this species and may play important roles in diuresis. We also identified candidates for hypothesized sodium and chloride channels. Detoxification genes were generally higher expressed in larvae. Significance: This study represents the first comparison of Malpighian tubule transcriptomes between larval and adult A. aegypti mosquitoes, highlighting key differences in their renal systems that arise as they transform from an aquatic filter-feeding larval stage to a terrestrial, blood-feeding adult stage.

RNA-Seq Comparison of Larval and Adult Malpighian Tubules of the Yellow Fever Mosquito Aedes aegypti Reveals Life Stage-Specific Changes in Renal Function

PubMed Central

Li, Yiyi; Piermarini, Peter M.; Esquivel, Carlos J.; Drumm, Hannah E.; Schilkey, Faye D.; Hansen, Immo A.

2017-01-01

Introduction: The life history of Aedes aegypti presents diverse challenges to its diuretic system. During the larval and pupal life stages mosquitoes are aquatic. With the emergence of the adult they become terrestrial. This shifts the organism within minutes from an aquatic environment to a terrestrial environment where dehydration has to be avoided. In addition, female mosquitoes take large blood meals, which present an entirely new set of challenges to salt and water homeostasis. Methods: To determine differences in gene expression associated with these different life stages, we performed an RNA-seq analysis of the main diuretic tissue in A. aegypti, the Malpighian tubules. We compared transcript abundance in 4th instar larvae to that of adult females and analyzed the data with a focus on transcripts that encode proteins potentially involved in diuresis, like water and solute channels as well as ion transporters. We compared our results against the model of potassium- and sodium chloride excretion in the Malpighian tubules proposed by Hine et al. (2014), which involves at least eight ion transporters and a proton-pump. Results: We found 3,421 of a total number of 17,478 (19.6%) unique transcripts with a P < 0.05 and at least a 2.5 fold change in expression levels between the two groups. We identified two novel transporter genes that are highly expressed in the adult Malpighian tubules, which have not previously been part of the transport model in this species and may play important roles in diuresis. We also identified candidates for hypothesized sodium and chloride channels. Detoxification genes were generally higher expressed in larvae. Significance: This study represents the first comparison of Malpighian tubule transcriptomes between larval and adult A. aegypti mosquitoes, highlighting key differences in their renal systems that arise as they transform from an aquatic filter-feeding larval stage to a terrestrial, blood-feeding adult stage. PMID:28536536

Effects of early life exposure to ultraviolet C radiation on mitochondrial DNA content, transcription, ATP production, and oxygen consumption in developing Caenorhabditis elegans

PubMed Central

2013-01-01

Background Mitochondrial DNA (mtDNA) is present in multiple copies per cell and undergoes dramatic amplification during development. The impacts of mtDNA damage incurred early in development are not well understood, especially in the case of types of mtDNA damage that are irreparable, such as ultraviolet C radiation (UVC)-induced photodimers. Methods We exposed first larval stage nematodes to UVC using a protocol that results in accumulated mtDNA damage but permits nuclear DNA (nDNA) repair. We then measured the transcriptional response, as well as oxygen consumption, ATP levels, and mtDNA copy number through adulthood. Results Although the mtDNA damage persisted to the fourth larval stage, we observed only a relatively minor ~40% decrease in mtDNA copy number. Transcriptomic analysis suggested an inhibition of aerobic metabolism and developmental processes; mRNA levels for mtDNA-encoded genes were reduced ~50% at 3 hours post-treatment, but recovered and, in some cases, were upregulated at 24 and 48 hours post-exposure. The mtDNA polymerase γ was also induced ~8-fold at 48 hours post-exposure. Moreover, ATP levels and oxygen consumption were reduced in response to UVC exposure, with marked reductions of ~50% at the later larval stages. Conclusions These results support the hypothesis that early life exposure to mitochondrial genotoxicants could result in mitochondrial dysfunction at later stages of life, thereby highlighting the potential health hazards of time-delayed effects of these genotoxicants in the environment. PMID:23374645

Transcriptome Analysis of Bombyx mori Larval Midgut during Persistent and Pathogenic Cytoplasmic Polyhedrosis Virus Infection

PubMed Central

Kolliopoulou, Anna; Van Nieuwerburgh, Filip; Stravopodis, Dimitrios J.; Deforce, Dieter; Swevers, Luc; Smagghe, Guy

2015-01-01

Many insects can be persistently infected with viruses but do not show any obvious adverse effects with respect to physiology, development or reproduction. Here, Bombyx mori strain Daizo, persistently infected with cytoplasmic polyhedrosis virus (BmCPV), was used to study the host’s transcriptional response after pathogenic infection with the same virus in midgut tissue of larvae persistently and pathogenically infected as 2nd and 4th instars. Next generation sequencing revealed that from 13,769 expressed genes, 167 were upregulated and 141 downregulated in both larval instars following pathogenic infection. Several genes that could possibly be involved in B. mori immune response against BmCPV or that may be induced by the virus in order to increase infectivity were identified, whereas classification of differentially expressed transcripts (confirmed by qRT-PCR) resulted in gene categories related to physical barriers, immune responses, proteolytic / metabolic enzymes, heat-shock proteins, hormonal signaling and uncharacterized proteins. Comparison of our data with the available literature (pathogenic infection of persistently vs. non-persistently infected larvae) unveiled various similarities of response in both cases, which suggests that pre-existing persistent infection does not affect in a major way the transcriptome response against pathogenic infection. To investigate the possible host’s RNAi response against BmCPV challenge, the differential expression of RNAi-related genes and the accumulation of viral small RNAs (vsRNAs) were studied. During pathogenic infection, siRNA-like traces like the 2-fold up-regulation of the core RNAi genes Ago-2 and Dcr-2 as well as a peak of 20 nt small RNAs were observed. Interestingly, vsRNAs of the same size were detected at lower rates in persistently infected larvae. Collectively, our data provide an initial assessment of the relative significance of persistent infection of silkworm larvae on the host response following pathogenic infection with CPV, while they also highlight the relative importance of RNAi as an antiviral mechanism. PMID:25816294

Dynamic genome wide expression profiling of Drosophila head development reveals a novel role of Hunchback in retinal glia cell development and blood-brain barrier integrity

PubMed Central

Torres-Oliva, Montserrat; Schneider, Julia; Wiegleb, Gordon

2018-01-01

Drosophila melanogaster head development represents a valuable process to study the developmental control of various organs, such as the antennae, the dorsal ocelli and the compound eyes from a common precursor, the eye-antennal imaginal disc. While the gene regulatory network underlying compound eye development has been extensively studied, the key transcription factors regulating the formation of other head structures from the same imaginal disc are largely unknown. We obtained the developmental transcriptome of the eye-antennal discs covering late patterning processes at the late 2nd larval instar stage to the onset and progression of differentiation at the end of larval development. We revealed the expression profiles of all genes expressed during eye-antennal disc development and we determined temporally co-expressed genes by hierarchical clustering. Since co-expressed genes may be regulated by common transcriptional regulators, we combined our transcriptome dataset with publicly available ChIP-seq data to identify central transcription factors that co-regulate genes during head development. Besides the identification of already known and well-described transcription factors, we show that the transcription factor Hunchback (Hb) regulates a significant number of genes that are expressed during late differentiation stages. We confirm that hb is expressed in two polyploid subperineurial glia cells (carpet cells) and a thorough functional analysis shows that loss of Hb function results in a loss of carpet cells in the eye-antennal disc. Additionally, we provide for the first time functional data indicating that carpet cells are an integral part of the blood-brain barrier. Eventually, we combined our expression data with a de novo Hb motif search to reveal stage specific putative target genes of which we find a significant number indeed expressed in carpet cells. PMID:29360820

Sex Change in Clownfish: Molecular Insights from Transcriptome Analysis.

PubMed

Casas, Laura; Saborido-Rey, Fran; Ryu, Taewoo; Michell, Craig; Ravasi, Timothy; Irigoien, Xabier

2016-10-17

Sequential hermaphroditism is a unique reproductive strategy among teleosts that is displayed mainly in fish species living in the coral reef environment. The reproductive biology of hermaphrodites has long been intriguing; however, very little is known about the molecular pathways underlying their sex change. Here, we provide the first de novo transcriptome analyses of a hermaphrodite teleost´s undergoing sex change in its natural environment. Our study has examined relative gene expression across multiple groups-rather than just two contrasting conditions- and has allowed us to explore the differential expression patterns throughout the whole process. Our analysis has highlighted the rapid and complex genomic response of the brain associated with sex change, which is subsequently transmitted to the gonads, identifying a large number of candidate genes, some well-known and some novel, involved in the process. The present study provides strong evidence of the importance of the sex steroidogenic machinery during sex change in clownfish, with the aromatase gene playing a central role, both in the brain and the gonad. This work constitutes the first genome-wide study in a social sex-changing species and provides insights into the genetic mechanism governing social sex change and gonadal restructuring in protandrous hermaphrodites.

Sex Change in Clownfish: Molecular Insights from Transcriptome Analysis

PubMed Central

Casas, Laura; Saborido-Rey, Fran; Ryu, Taewoo; Michell, Craig; Ravasi, Timothy; Irigoien, Xabier

2016-01-01

Sequential hermaphroditism is a unique reproductive strategy among teleosts that is displayed mainly in fish species living in the coral reef environment. The reproductive biology of hermaphrodites has long been intriguing; however, very little is known about the molecular pathways underlying their sex change. Here, we provide the first de novo transcriptome analyses of a hermaphrodite teleost´s undergoing sex change in its natural environment. Our study has examined relative gene expression across multiple groups—rather than just two contrasting conditions— and has allowed us to explore the differential expression patterns throughout the whole process. Our analysis has highlighted the rapid and complex genomic response of the brain associated with sex change, which is subsequently transmitted to the gonads, identifying a large number of candidate genes, some well-known and some novel, involved in the process. The present study provides strong evidence of the importance of the sex steroidogenic machinery during sex change in clownfish, with the aromatase gene playing a central role, both in the brain and the gonad. This work constitutes the first genome-wide study in a social sex-changing species and provides insights into the genetic mechanism governing social sex change and gonadal restructuring in protandrous hermaphrodites. PMID:27748421

Dual-compartmental transcriptomic + proteomic analysis of a marine endosymbiosis exposed to environmental change.

PubMed

Mayfield, Anderson B; Wang, Yu-Bin; Chen, Chii-Shiarng; Chen, Shu-Hwa; Lin, Chung-Yen

2016-12-01

As significant anthropogenic pressures are putting undue stress on the world's oceans, there has been a concerted effort to understand how marine organisms respond to environmental change. Transcriptomic approaches, in particular, have been readily employed to document the mRNA-level response of a plethora of marine invertebrates exposed to an array of simulated stress scenarios, with the tacit and untested assumption being that the respective proteins show a corresponding trend. To better understand the degree of congruency between mRNA and protein expression in an endosymbiotic marine invertebrate, mRNAs and proteins were sequenced from the same samples of the common, Indo-Pacific coral Seriatopora hystrix exposed to stable or upwelling-simulating conditions for 1 week. Of the 167 proteins downregulated at variable temperature, only two were associated with mRNAs that were also differentially expressed between treatments. Of the 378 differentially expressed genes, none were associated with a differentially expressed protein. Collectively, these results highlight the inherent risk of inferring cellular behaviour based on mRNA expression data alone and challenge the current, mRNA-focused approach taken by most marine and many molecular biologists. © 2016 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

Staying alive in adversity: transcriptome dynamics in the stress-resistant dauer larva.

PubMed

Holt, Suzan J

2006-10-01

In response to food depletion and overcrowding, the soil nematode Caenorhabditis elegans can arrest development and form an alternate third larval stage called the dauer. Though nonfeeding, the dauer larva is long lived and stress resistant. Metabolic and transcription rates are lowered but the transcriptome of the dauer is complex. In this study, distribution analysis of transcript profiles generated by Serial Analysis of Gene Expression (SAGE) in dauer larvae and in mixed developmental stages is presented. An inverse relationship was observed between frequency and abundance/copy number of SAGE tag types (transcripts) in both profiles. In the dauer profile, a relatively greater proportion of highly abundant transcripts was counterbalanced by a smaller fraction of low to moderately abundant transcripts. Comparisons of abundant tag counts between the two profiles revealed relative enrichment in the dauer profile of transcripts with predicted or known involvement in ribosome biogenesis and protein synthesis, membrane transport, and immune responses. Translation-coupled mRNA decay is proposed as part of an immune-like stress response in the dauer larva. An influence of genomic region on transcript level may reflect the coordination of transcription and mRNA turnover.

Coastal circulation and sediment dynamics in Maunalua Bay, Oahu, Hawaii, measurements of waves, currents, temperature, salinity, and turbidity; November 2008-February 2009

USGS Publications Warehouse

Storlazzi, Curt D.; Presto, M. Katherine; Logan, Joshua B.; Field, Michael E.

2010-01-01

High-resolution measurements of waves, currents, water levels, temperature, salinity and turbidity were made in Maunalua Bay, southern Oahu, Hawaii, during the 2008-2009 winter to better understand coastal circulation, water-column properties, and sediment dynamics during a range of conditions (trade winds, kona storms, relaxation of trade winds, and south swells). A series of bottom-mounted instrument packages were deployed in water depths of 20 m or less to collect long-term, high-resolution measurements of waves, currents, water levels, temperature, salinity, and turbidity. These data were supplemented with a series of profiles through the water column to characterize the vertical and spatial variability in water-column properties within the bay. These measurements support the ongoing process studies being done as part of the U.S. Geological Survey (USGS) Coastal and Marine Geology Program's Pacific Coral Reef Project; the ultimate goal of these studies is to better understand the transport mechanisms of sediment, larvae, pollutants, and other particles in coral reef settings. Project Objectives The objective of this study was to understand the temporal variations in currents, waves, tides, temperature, salinity and turbidity within a coral-lined embayment that receives periodic discharges of freshwater and sediment from multiple terrestrial sources in the Maunalua Bay. Instrument packages were deployed for a three-month period during the 2008-2009 winter and a series of vertical profiles were collected in November 2008, and again in February 2009, to characterize water-column properties within the bay. Measurements of flow and water-column properties in Maunalua Bay provided insight into the potential fate of terrestrial sediment, nutrient, or contaminant delivered to the marine environment and coral larval transport within the embayment. Such data are useful for providing baseline information for future watershed decisions and for establishing guidelines for the U.S. Coral Reef Task Force's (USCRTF) Hawaiian Local Action Strategy to address Land-Based Pollution (LAS-LBP) threats to coral reefs adjacent to the urbanized watersheds of Manualua Bay. Study Area Maunalua Bay is on the south side of Oahu, Hawaii, and is approximately 10 km long and 3 km wide. The bay is flanked by two large, dormant craters: Koko Head to the east and Diamond Head to the west. Rainfall in the watersheds that drain into Maunalua Bay ranges from more than 200 cm/year at the top of the Ko'olau Range that borders the northwestern part of the bay to less than 70 cm/year to the east at Koko Head. Seven major channels flow into the bay, and all but one have been altered by engineering structures.

Geographical variation in sound production in the anemonefish Amphiprion akallopisos.

PubMed

Parmentier, E; Lagardère, J P; Vandewalle, P; Fine, M L

2005-08-22

Because of pelagic-larval dispersal, coral-reef fishes are distributed widely with minimal genetic differentiation between populations. Amphiprion akallopisos, a clownfish that uses sound production to defend its anemone territory, has a wide but disjunct distribution in the Indian Ocean. We compared sounds produced by these fishes from populations in Madagascar and Indonesia, a distance of 6500 km. Differentiation of agonistic calls into distinct types indicates a complexity not previously recorded in fishes' acoustic communication. Moreover, various acoustic parameters, including peak frequency, pulse duration, number of peaks per pulse, differed between the two populations. The geographic comparison is the first to demonstrate 'dialects' in a marine fish species, and these differences in sound parameters suggest genetic divergence between these two populations. These results highlight the possible approach for investigating the role of sounds in fish behaviour in reproductive divergence and speciation.

Interspecific variation in potential importance of planktivorous damselfishes as predators of Acanthaster sp. eggs

NASA Astrophysics Data System (ADS)

Cowan, Zara-Louise; Ling, Scott D.; Dworjanyn, Symon A.; Caballes, Ciemon F.; Pratchett, Morgan S.

2017-06-01

Coral-eating crown-of-thorns starfish ( Acanthaster sp.) often exhibit dramatic population outbreaks, suggesting that their local abundance may be relatively unchecked by predators. This may be due to high concentrations of anti-predator chemicals (saponins and plancitoxins), but the effectiveness of chemical deterrents in protecting Acanthaster sp., especially spawned eggs, from predation remains controversial. We show that planktivorous damselfishes will readily consume food pellets with low proportions (≤80%) of eggs of crown-of-thorns starfish. However, all fishes exhibited increasing rejection of food pellets with higher proportions of starfish eggs, suggesting that chemicals in eggs of crown-of-thorns starfish do deter potential predators. Interestingly, palatability thresholds varied greatly among the nine species of planktivorous fish tested. Most notably, Amblyglyphidodon curacao consumed food pellets comprising 100% starfish eggs 1.5 times more than any other fish species, and appeared largely insensitive to increases in the concentration of starfish eggs. After standardising for size, smaller fish species consumed a disproportionate amount of pellets comprising high proportions of starfish eggs, indicating that abundant small-bodied fishes could be particularly important in regulating larval abundance and settlement success of crown-of-thorns starfish. Collectively, this study shows that reef fishes vary in their tolerance to anti-predator chemicals in crown-of-thorns starfish and may represent important predators on early life-history stages.

Genetic discontinuity among regional populations of Lophelia pertusa in the North Atlantic Ocean

USGS Publications Warehouse

Morrison, C.L.; Ross, Steve W.; Nizinski, M.S.; Brooke, S.; Jarnegren, J.; Waller, R.G.; Johnson, Robin L.; King, T.L.

2011-01-01

Knowledge of the degree to which populations are connected through larval dispersal is imperative to effective management, yet little is known about larval dispersal ability or population connectivity in Lophelia pertusa, the dominant framework-forming coral on the continental slope in the North Atlantic Ocean. Using nine microsatellite DNA markers, we assessed the spatial scale and pattern of genetic connectivity across a large portion of the range of L. pertusa in the North Atlantic Ocean. A Bayesian modeling approach found four distinct genetic groupings corresponding to ocean regions: Gulf of Mexico, coastal southeastern U.S., New England Seamounts, and eastern North Atlantic Ocean. An isolation-by-distance pattern was supported across the study area. Estimates of pairwise population differentiation were greatest with the deepest populations, the New England Seamounts (average F ST = 0.156). Differentiation was intermediate with the eastern North Atlantic populations (F ST = 0.085), and smallest between southeastern U.S. and Gulf of Mexico populations (F ST = 0.019), with evidence of admixture off the southeastern Florida peninsula. Connectivity across larger geographic distances within regions suggests that some larvae are broadly dispersed. Heterozygote deficiencies were detected within the majority of localities suggesting deviation from random mating. Gene flow between ocean regions appears restricted, thus, the most effective management scheme for L. pertusa involves regional reserve networks.

Connectivity dominates larval replenishment in a coastal reef fish metapopulation

PubMed Central

Saenz-Agudelo, Pablo; Jones, Geoffrey P.; Thorrold, Simon R.; Planes, Serge

2011-01-01

Direct estimates of larval retention and connectivity are essential to understand the structure and dynamics of marine metapopulations, and optimize the size and spacing of reserves within networks of marine-protected areas (MPAs). For coral reef fishes, while there are some empirical estimates of self-recruitment at isolated populations, exchange among sub-populations has been rarely quantified. Here, we used microsatellite DNA markers and a likelihood-based parentage analysis to assess the relative magnitude of self-recruitment and exchange among eight geographically distinct sub-populations of the panda clownfish Amphiprion polymnus along 30 km of coastline near Port Moresby, Papua New Guinea. In addition, we used an assignment/exclusion test to identify immigrants arriving from genetically distinct sources. Overall, 82 per cent of the juveniles were immigrants while 18 per cent were progeny of parents genotyped in our focal metapopulation. Of the immigrants, only 6 per cent were likely to be genetically distinct from the focal metapopulation, suggesting most of the connectivity is among sub-populations from a rather homogeneous genetic pool. Of the 18 per cent that were progeny of known adults, two-thirds dispersed among the eight sub-populations and only one-third settled back into natal sub-populations. Comparison of our data with previous studies suggested that variation in dispersal distances is likely to be influenced by the geographical setting and spacing of sub-populations. PMID:21325328

Connectivity dominates larval replenishment in a coastal reef fish metapopulation.

PubMed

Saenz-Agudelo, Pablo; Jones, Geoffrey P; Thorrold, Simon R; Planes, Serge

2011-10-07

Direct estimates of larval retention and connectivity are essential to understand the structure and dynamics of marine metapopulations, and optimize the size and spacing of reserves within networks of marine-protected areas (MPAs). For coral reef fishes, while there are some empirical estimates of self-recruitment at isolated populations, exchange among sub-populations has been rarely quantified. Here, we used microsatellite DNA markers and a likelihood-based parentage analysis to assess the relative magnitude of self-recruitment and exchange among eight geographically distinct sub-populations of the panda clownfish Amphiprion polymnus along 30 km of coastline near Port Moresby, Papua New Guinea. In addition, we used an assignment/exclusion test to identify immigrants arriving from genetically distinct sources. Overall, 82 per cent of the juveniles were immigrants while 18 per cent were progeny of parents genotyped in our focal metapopulation. Of the immigrants, only 6 per cent were likely to be genetically distinct from the focal metapopulation, suggesting most of the connectivity is among sub-populations from a rather homogeneous genetic pool. Of the 18 per cent that were progeny of known adults, two-thirds dispersed among the eight sub-populations and only one-third settled back into natal sub-populations. Comparison of our data with previous studies suggested that variation in dispersal distances is likely to be influenced by the geographical setting and spacing of sub-populations.

Transcriptomics of coping strategies in free-swimming Lepeophtheirus salmonis (Copepoda) larvae responding to abiotic stress.

PubMed

Sutherland, Ben J G; Jantzen, Stuart G; Yasuike, Motoshige; Sanderson, Dan S; Koop, Ben F; Jones, Simon R M

2012-12-01

The salmon louse Lepeophtheirus salmonis is a marine ectoparasite of wild and farmed salmon in the Northern Hemisphere. Infections of farmed salmon are of economic and ecological concern. Nauplius and copepodid salmon lice larvae are free-swimming and disperse in the water column until they encounter a host. In this study, we characterized the sublethal stress responses of L. salmonis copepodid larvae by applying a 38K oligonucleotide microarray to profile transcriptomes following 24 h exposures to suboptimal salinity (30-10 parts per thousand (‰)) or temperature (16-4 °C) environments. Hyposalinity exposure resulted in large-scale gene expression changes relative to those elicited by a thermal gradient. Subsequently, transcriptome responses to a more finely resolved salinity gradient between 30 ‰ and 25 ‰ were profiled. Minimal changes occurred at 29 ‰ or 28 ‰, a threshold of response was identified at 27 ‰, and the largest response was at 25 ‰. Differentially expressed genes were clustered by pattern of expression, and clusters were characterized by functional enrichment analysis. Results indicate larval copepods adopt two distinct coping strategies in response to short-term hyposaline stress: a primary response using molecular chaperones and catabolic processes at 27 ‰; and a secondary response up-regulating ion pumps, transporters, a different suite of chaperones and apoptosis-related transcripts at 26 ‰ and 25 ‰. The results further our understanding of the tolerances of L. salmonis copepodids to salinity and temperature gradients and may assist in the development of salmon louse management strategies. © 2012 Blackwell Publishing Ltd.

Identification and characterization of plant cell wall degrading enzymes from three glycoside hydrolase families in the cerambycid beetle Apriona japonica.

PubMed

Pauchet, Yannick; Kirsch, Roy; Giraud, Sandra; Vogel, Heiko; Heckel, David G

2014-06-01

Xylophagous insects have evolved to thrive in a highly challenging environment. For example, wood-boring beetles from the family Cerambycidae feed exclusively on woody tissues, and to efficiently access the nutrients present in this sub-optimal environment, they have to cope with the lignocellulose barrier. Whereas microbes of the insect's gut flora were hypothesized to be responsible for the degradation of lignin, the beetle itself depends heavily on the secretion of a range of enzymes, known as plant cell wall degrading enzymes (PCWDEs), to efficiently digest both hemicellulose and cellulose networks. Here we sequenced the larval gut transcriptome of the Mulberry longhorn beetle, Apriona japonica (Cerambycidae, Lamiinae), in order to investigate the arsenal of putative PCWDEs secreted by this species. We combined our transcriptome with all available sequencing data derived from other cerambycid beetles in order to analyze and get insight into the evolutionary history of the corresponding gene families. Finally, we heterologously expressed and functionally characterized the A. japonica PCWDEs we identified from the transcriptome. Together with a range of endo-β-1,4-glucanases, we describe here for the first time the presence in a species of Cerambycidae of (i) a xylanase member of the subfamily 2 of glycoside hydrolase family 5 (GH5 subfamily 2), as well as (ii) an exopolygalacturonase from family GH28. Our analyses greatly contribute to a better understanding of the digestion physiology of this important group of insects, many of which are major pests of forestry worldwide. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evaluation of a novel Dot-ELISA assay utilizing a recombinant protein for the effective diagnosis of Taenia pisiformis larval infections.

PubMed

Chen, Lin; Yang, Deying; Gu, Xiaobin; Peng, Xuerong; Yang, Guangyou

2014-08-29

Cysticercosis, caused by the larvae of Taenia pisiformis, is a common disease in domestic breeds of the rabbit Oryctolagus cuniculus that results in economic losses. At present, there is no convenient and effective method for the rapid detection of T. pisiformis larvae. Here, we developed and tested the efficacy of a Dot-ELISA assay for the diagnosis of T. pisiformis larval infections in rabbits, based on the expression of the recombinant fusion protein (rTp1) from the Tp1 gene. Rapid amplification of cDNA ends (RACE) was used to amplify the 3' ends of the Tp1 gene, based on the unigene similar to Ts1 gene (EU009656.1) which comes from transcriptome sequencing of T. pisiformis. The Tp1 gene was successfully amplified, cloned and expressed in BL21 (DE3). Western blot analysis revealed that the recombinant Tp1 protein is specifically recognized by rabbit T. pisiformis cysticercosis antisera. This purified recombinant fusion protein, rTp1, was probed by Dot-ELISA with sera from rabbits infected with T. pisiformis larvae and with other parasitic infections. Results showed that this Dot-ELISA assay had both high sensitivity (92.9-97.6%) and specificity (95.2-98.4%) to detect T. pisiformis larval infections. We also found very low levels of cross-reaction with other parasitic infections. This study has revealed that our novel Dot-ELISA assay utilizing the recombinant fusion protein, rTp1, has a strong potential for the effective diagnosis of T. pisiformis infections in rabbits. Copyright © 2014 Elsevier B.V. All rights reserved.

Genes Involved in the Evolution of Herbivory by a Leaf-Mining, Drosophilid Fly

PubMed Central

Whiteman, Noah K.; Gloss, Andrew D.; Sackton, Timothy B.; Groen, Simon C.; Humphrey, Parris T.; Lapoint, Richard T.; Sønderby, Ida E.; Halkier, Barbara A.; Kocks, Christine; Ausubel, Frederick M.; Pierce, Naomi E.

2012-01-01

Herbivorous insects are among the most successful radiations of life. However, we know little about the processes underpinning the evolution of herbivory. We examined the evolution of herbivory in the fly, Scaptomyza flava, whose larvae are leaf miners on species of Brassicaceae, including the widely studied reference plant, Arabidopsis thaliana (Arabidopsis). Scaptomyza flava is phylogenetically nested within the paraphyletic genus Drosophila, and the whole genome sequences available for 12 species of Drosophila facilitated phylogenetic analysis and assembly of a transcriptome for S. flava. A time-calibrated phylogeny indicated that leaf mining in Scaptomyza evolved between 6 and 16 million years ago. Feeding assays showed that biosynthesis of glucosinolates, the major class of antiherbivore chemical defense compounds in mustard leaves, was upregulated by S. flava larval feeding. The presence of glucosinolates in wild-type (WT) Arabidopsis plants reduced S. flava larval weight gain and increased egg–adult development time relative to flies reared in glucosinolate knockout (GKO) plants. An analysis of gene expression differences in 5-day-old larvae reared on WT versus GKO plants showed a total of 341 transcripts that were differentially regulated by glucosinolate uptake in larval S. flava. Of these, approximately a third corresponded to homologs of Drosophila melanogaster genes associated with starvation, dietary toxin-, heat-, oxidation-, and aging-related stress. The upregulated transcripts exhibited elevated rates of protein evolution compared with unregulated transcripts. The remaining differentially regulated transcripts also contained a higher proportion of novel genes than the unregulated transcripts. Thus, the transition to herbivory in Scaptomyza appears to be coupled with the evolution of novel genes and the co-option of conserved stress-related genes. PMID:22813779

Larval Red Drum (Sciaenops ocellatus) Sublethal Exposure to Weathered Deepwater Horizon Crude Oil: Developmental and Transcriptomic Consequences.

PubMed

Xu, Elvis Genbo; Khursigara, Alex J; Magnuson, Jason; Hazard, E Starr; Hardiman, Gary; Esbaugh, Andrew J; Roberts, Aaron P; Schlenk, Daniel

2017-09-05

The Deepwater Horizon (DWH) incident resulted in extensive oiling of the pelagic zone and shoreline habitats of many commercially important fish species. Exposure to the water-accommodated fraction (WAF) of oil from the spill causes developmental toxicity through cardiac defects in pelagic fish species. However, few studies have evaluated the effects of the oil on near-shore estuarine fish species such as red drum (Sciaenops ocellatus). Following exposure to a certified weathered slick oil (4.74 μg/L ∑PAH 50 ) from the DWH event, significant sublethal impacts were observed ranging from impaired nervous system development [average 17 and 22% reductions in brain and eye area at 48 h postfertilization (hpf), respectively] to abnormal cardiac morphology (100% incidence at 24, 48, and 72 hpf) in red drum larvae. Consistent with the phenotypic responses, significantly differentially expressed transcripts, enriched gene ontology, and altered functions and canonical pathways predicted adverse outcomes in nervous and cardiovascular systems, with more pronounced changes at later larval stages. Our study demonstrated that the WAF of weathered slick oil of DWH caused morphological abnormalities predicted by a suite of advanced bioinformatic tools in early developing red drum and also provided the basis for a better understanding of molecular mechanisms of crude oil toxicity in fish.

Habitat selection by marine larvae in changing chemical environments.

PubMed

Lecchini, D; Dixson, D L; Lecellier, G; Roux, N; Frédérich, B; Besson, M; Tanaka, Y; Banaigs, B; Nakamura, Y

2017-01-15

The replenishment and persistence of marine species is contingent on dispersing larvae locating suitable habitat and surviving to a reproductive stage. Pelagic larvae rely on environmental cues to make behavioural decisions with chemical information being important for habitat selection at settlement. We explored the sensory world of crustaceans and fishes focusing on the impact anthropogenic alterations (ocean acidification, red soil, pesticide) have on conspecific chemical signals used by larvae for habitat selection. Crustacean (Stenopus hispidus) and fish (Chromis viridis) larvae recognized their conspecifics via chemical signals under control conditions. In the presence of acidified water, red soil or pesticide, the ability of larvae to chemically recognize conspecific cues was altered. Our study highlights that recruitment potential on coral reefs may decrease due to anthropogenic stressors. If so, populations of fishes and crustaceans will continue their rapid decline; larval recruitment will not replace and sustain the adult populations on degraded reefs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chemical Ecology of Chemosensation in Asteroidea: Insights Towards Management Strategies of Pest Species.

PubMed

Motti, Cherie A; Bose, Utpal; Roberts, Rebecca E; McDougall, Carmel; Smith, Meaghan K; Hall, Michael R; Cummins, Scott F

2018-02-01

Within the Phylum Echinodermata, the class Asteroidea, commonly known as starfish and sea stars, encompasses a large number of benthos inhabiting genera and species with various feeding modalities including herbivores, carnivores, omnivores and detritivores. The Asteroidea rely on chemosensation throughout their life histories including hunting prey, avoiding or deterring predators, in the formation of spawning aggregations, synchronizing gamete release and targeting appropriate locations for larval settlement. The identities of many of the chemical stimuli that mediate these physiological and behavioural processes remain unresolved even though evidence indicates they play pivotal roles in the functionality of benthic communities. Aspects of chemosensation, as well as putative chemically-mediated behaviours and the molecular mechanisms of chemoreception, within the Asteroidea are reviewed here, with particular reference to the coral reef pest the Crown-of-Thorns starfish Acanthaster planci species complex, in the context of mitigation of population outbreaks.

Geographical variation in sound production in the anemonefish Amphiprion akallopisos

PubMed Central

Parmentier, E; Lagardère, J.P; Vandewalle, P; Fine, M.L

2005-01-01

Because of pelagic-larval dispersal, coral-reef fishes are distributed widely with minimal genetic differentiation between populations. Amphiprion akallopisos, a clownfish that uses sound production to defend its anemone territory, has a wide but disjunct distribution in the Indian Ocean. We compared sounds produced by these fishes from populations in Madagascar and Indonesia, a distance of 6500 km. Differentiation of agonistic calls into distinct types indicates a complexity not previously recorded in fishes' acoustic communication. Moreover, various acoustic parameters, including peak frequency, pulse duration, number of peaks per pulse, differed between the two populations. The geographic comparison is the first to demonstrate ‘dialects’ in a marine fish species, and these differences in sound parameters suggest genetic divergence between these two populations. These results highlight the possible approach for investigating the role of sounds in fish behaviour in reproductive divergence and speciation. PMID:16087425

Nanoscale Transforming Mineral Phases in Fresh Nacre.

PubMed

DeVol, Ross T; Sun, Chang-Yu; Marcus, Matthew A; Coppersmith, Susan N; Myneni, Satish C B; Gilbert, Pupa U P A

2015-10-21

Nacre, or mother-of-pearl, the iridescent inner layer of many mollusk shells, is a biomineral lamellar composite of aragonite (CaCO3) and organic sheets. Biomineralization frequently occurs via transient amorphous precursor phases, crystallizing into the final stable biomineral. In nacre, despite extensive attempts, amorphous calcium carbonate (ACC) precursors have remained elusive. They were inferred from non-nacre-forming larval shells, or from a residue of amorphous material surrounding mature gastropod nacre tablets, and have only once been observed in bivalve nacre. Here we present the first direct observation of ACC precursors to nacre formation, obtained from the growth front of nacre in gastropod shells from red abalone (Haliotis rufescens), using synchrotron spectromicroscopy. Surprisingly, the abalone nacre data show the same ACC phases that are precursors to calcite (CaCO3) formation in sea urchin spicules, and not proto-aragonite or poorly crystalline aragonite (pAra), as expected for aragonitic nacre. In contrast, we find pAra in coral.

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeVol, Ross T.; Sun, Chang-Yu; Marcus, Matthew A.

Nacre, or mother-of-pearl, the iridescent inner layer of many mollusk shells, is a biomineral lamellar composite of aragonite (CaCO 3) and organic sheets. Biomineralization frequently occurs via transient amorphous precursor phases, crystallizing into the final stable biomineral. In nacre, despite extensive attempts, amorphous calcium carbonate (ACC) precursors have remained elusive. They were inferred from non-nacre-forming larval shells, or from a residue of amorphous material surrounding mature gastropod nacre tablets, and have only once been observed in bivalve nacre. Here we present the first direct observation of ACC precursors to nacre formation, obtained from the growth front of nacre in gastropodmore » shells from red abalone (Haliotis rufescens), using synchrotron spectromicroscopy. Surprisingly, the abalone nacre data show the same ACC phases that are precursors to calcite (CaCO 3) formation in sea urchin spicules, and not proto-aragonite or poorly crystalline aragonite (pAra), as expected for aragonitic nacre. In contrast, we find pAra in coral.« less

The Holo-Transcriptome of the Zoantharian Protopalythoa variabilis (Cnidaria: Anthozoa): A Plentiful Source of Enzymes for Potential Application in Green Chemistry, Industrial and Pharmaceutical Biotechnology.

PubMed

R L Morlighem, Jean-Étienne; Huang, Chen; Liao, Qiwen; Braga Gomes, Paula; Daniel Pérez, Carlos; de Brandão Prieto-da-Silva, Álvaro Rossan; Ming-Yuen Lee, Simon; Rádis-Baptista, Gandhi

2018-06-13

Marine invertebrates, such as sponges, tunicates and cnidarians (zoantharians and scleractinian corals), form functional assemblages, known as holobionts, with numerous microbes. This type of species-specific symbiotic association can be a repository of myriad valuable low molecular weight organic compounds, bioactive peptides and enzymes. The zoantharian Protopalythoa variabilis (Cnidaria: Anthozoa) is one such example of a marine holobiont that inhabits the coastal reefs of the tropical Atlantic coast and is an interesting source of secondary metabolites and biologically active polypeptides. In the present study, we analyzed the entire holo-transcriptome of P. variabilis , looking for enzyme precursors expressed in the zoantharian-microbiota assemblage that are potentially useful as industrial biocatalysts and biopharmaceuticals. In addition to hundreds of predicted enzymes that fit into the classes of hydrolases, oxidoreductases and transferases that were found, novel enzyme precursors with multiple activities in single structures and enzymes with incomplete Enzyme Commission numbers were revealed. Our results indicated the predictive expression of thirteen multifunctional enzymes and 694 enzyme sequences with partially characterized activities, distributed in 23 sub-subclasses. These predicted enzyme structures and activities can prospectively be harnessed for applications in diverse areas of industrial and pharmaceutical biotechnology.

Polarized light sensitivity and orientation in coral reef fish post-larvae.

PubMed

Berenshtein, Igal; Kiflawi, Moshe; Shashar, Nadav; Wieler, Uri; Agiv, Haim; Paris, Claire B

2014-01-01

Recent studies of the larvae of coral-reef fishes reveal that these tiny vertebrates possess remarkable swimming capabilities, as well as the ability to orient to olfactory, auditory, and visual cues. While navigation according to reef-generated chemicals and sounds can significantly affect dispersal, the effect is limited to the vicinity of the reef. Effective long-distance navigation requires at least one other capacity-the ability to maintain a bearing using, for example, a sun compass. Directional information in the sun's position can take the form of polarized-light related cues (i.e., e-vector orientation and percent polarization) and/or non-polarized-light related cues (i.e., the direct image of the sun, and the brightness and spectral gradients). We examined the response to both types of cues using commercially-reared post-larvae of the spine-cheeked anemonefish Premnas biaculeatus. Initial optomotor trials indicated that the post-larval stages are sensitive to linearly polarized light. Swimming directionality was then tested using a Drifting In-Situ Chamber (DISC), which allowed us to examine the response of the post-larvae to natural variation in light conditions and to manipulated levels of light polarization. Under natural light conditions, 28 of 29 post-larvae showed significant directional swimming (Rayleigh's test p<0.05, R = 0.74±0.23), but to no particular direction. Swimming directionality was positively affected by sky clarity (absence of clouds and haze), which explained 38% of the observed variation. Moreover, post-larvae swimming under fully polarized light exhibited a distinct behavior of tracking the polarization axis, as it rotated along with the DISC. This behavior was not observed under partially-polarized illumination. We view these findings as an indication for the use of sun-related cues, and polarized light signal in specific, by orienting coral-reef fish larvae.

Polarized Light Sensitivity and Orientation in Coral Reef Fish Post-Larvae

PubMed Central

Berenshtein, Igal; Kiflawi, Moshe; Shashar, Nadav; Wieler, Uri; Agiv, Haim; Paris, Claire B.

2014-01-01

Recent studies of the larvae of coral-reef fishes reveal that these tiny vertebrates possess remarkable swimming capabilities, as well as the ability to orient to olfactory, auditory, and visual cues. While navigation according to reef-generated chemicals and sounds can significantly affect dispersal, the effect is limited to the vicinity of the reef. Effective long-distance navigation requires at least one other capacity–the ability to maintain a bearing using, for example, a sun compass. Directional information in the sun’s position can take the form of polarized-light related cues (i.e., e-vector orientation and percent polarization) and/or non-polarized-light related cues (i.e., the direct image of the sun, and the brightness and spectral gradients). We examined the response to both types of cues using commercially-reared post-larvae of the spine-cheeked anemonefish Premnas biaculeatus. Initial optomotor trials indicated that the post-larval stages are sensitive to linearly polarized light. Swimming directionality was then tested using a Drifting In-Situ Chamber (DISC), which allowed us to examine the response of the post-larvae to natural variation in light conditions and to manipulated levels of light polarization. Under natural light conditions, 28 of 29 post-larvae showed significant directional swimming (Rayleigh’s test p<0.05, R = 0.74±0.23), but to no particular direction. Swimming directionality was positively affected by sky clarity (absence of clouds and haze), which explained 38% of the observed variation. Moreover, post-larvae swimming under fully polarized light exhibited a distinct behavior of tracking the polarization axis, as it rotated along with the DISC. This behavior was not observed under partially-polarized illumination. We view these findings as an indication for the use of sun-related cues, and polarized light signal in specific, by orienting coral-reef fish larvae. PMID:24516662

Deep sequencing of the prothoracic gland transcriptome reveals new players in insect ecdysteroidogenesis

PubMed Central

Nakaoka, Takayoshi; Iga, Masatoshi; Yamada, Tetsuya; Koujima, Ikumi; Takeshima, Mika; Zhou, Xiangying; Suzuki, Yutaka; Ogihara, Mari H.; Kataoka, Hiroshi

2017-01-01

Ecdysteroids are steroid hormones that induce molting and determine developmental timing in arthropods. In insect larva, the prothoracic gland (PG) is a major organ for ecdysone synthesis and release. Released ecdysone is converted into the active form, 20-hydroxyecdysone (20E) in the peripheral tissues. All processes from ecdysone synthesis and release from the PG to its conversion to 20E are called ecdysteroidogenesis and are under the regulation of numerous factors expressed in the PG and peripheral tissues. Classical genetic approaches and recent transcriptomic screening in the PG identified several genes responsible for ecdysone synthesis and release, whereas the regulatory mechanism remains largely unknown. We analyzed RNA-seq data of the silkworm Bombyx mori PG and employed the fruit fly Drosophila melanogaster GAL4/UAS binary RNAi system to comprehensively screen for genes involved in ecdysone synthesis and/or release. We found that the genes encoding δ-aminolevulinic acid synthase (CG3017/alas) and putative NAD kinase (CG33156) were highly expressed in the PG of both B. mori and D. melanogaster. Neither alas nor CG33156 RNAi-induced larvae could enter into the pupal stage, and they had a lower abundance of the active form ecdysteroids in their prolonged larval stage. These results demonstrated that alas and CG33156 are indispensable for ecdysteroidogenesis. PMID:28257485

Comparative transcriptome analysis of Sogatella furcifera (Horváth) exposed to different insecticides.

PubMed

Zhou, Cao; Yang, Hong; Wang, Zhao; Long, Gui-Yun; Jin, Dao-Chao

2018-06-08

White-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae), one of the main agricultural insect pests in China, is resistant to a wide variety of insecticides. We used transcriptome analysis to compare the expression patterns of resistance- and stress-response genes in S. furcifera subjected to imidacloprid, deltamethrin, and triazophos stress, to determine the molecular mechanisms of resistance to these insecticides. A comparative analysis of gene expression under imidacloprid, deltamethrin, and triazophos stress revealed 1,123, 841, and 316 upregulated unigenes, respectively, compared to the control. These upregulated genes included seven P450s (two CYP2 clade, three CYP3 clade, and two CYP4 clade), one GST, one ABC transporter (ABCF), and seven Hsps (one 90 and six Hsp70s) under imidacloprid stress; one P450 (CYP3 clade), two ABC transporters (one ABCF and one ABCD), and one Hsp (Hsp90) under deltamethrin stress; one P450 (CYP3 clade) and one ABC transporter (ABCF) under triazophos stress. In addition, 80 genes were commonly upregulated in response to the three insecticide treatments, including laminin, larval cuticle protein, and fasciclin, which are associated with epidermal formation. These results provide a valuable resource for the molecular characterisation of insecticide action in S. furcifera, especially the molecular characteristics of insecticide cross resistance.

Effect of Extremes: How El Niño Events Affect Reef Fish Population Connectivity in the Hawaiian Islands

NASA Astrophysics Data System (ADS)

Wren, J.; Toonen, R. J.

2016-02-01

As a result of climate change, scientists predict stronger, more frequent El Niño events in the future. These events in the Central Equatorial Pacific cause increased sea surface temperatures (SST), a depressed thermocline, and decreased primary production. The oceanographic effects in the Hawaiian Archipelago located in the Subtropical North Pacific, are not equally well understood, and have shown both increased and decreased SST and primary production during El Niño events. Marine larval fish development rates can be affected by factors such as food availability and temperature, thus oceanographic changes caused by El Niño can potentially alter larval dispersal patterns throughout the Hawaiian Archipelago, affecting regional population connectivity. Using a two dimensional Lagrangian particle dispersal model coupled with high resolution Hybrid Coordinate Ocean Model (HYCOM) currents for the Hawaiian Archipelago we are able to model annual settlement probabilities and self-recruitment, important metrics for understanding population dynamics and connectivity. Preliminary data comparing modeled dispersal during the 1997-98 El Niño with four years of normal state oceanographic conditions (2011-2014), showed an increase in total settlement during the El Niño years for the North Western Hawaiian Islands, and a decreased settlement success for the Main Hawaiian Islands. Self-recruitment across the archipelago was lower during El Niño and the distance the successful settlers traveled was greater, indicating that El Niño may be playing an important role in long distance dispersal and genetic exchange between distant sites not otherwise connected. We see a much greater connectivity between the Hawaiian Archipelago and Johnnston Atoll during the El Niño event, with a significant increase of larval exchange in both directions. Since these ecologically rare but extreme events can have a disproportionate influence on dispersal, it's important to understand how connectivity is affected in order to manage for diverse coral reefs in the future.

De novo transcriptome assembly and differential gene expression analysis of the calanoid copepod Acartia tonsa exposed to nickel nanoparticles.

PubMed

Zhou, Chao; Carotenuto, Ylenia; Vitiello, Valentina; Wu, Changwen; Zhang, Jianshe; Buttino, Isabella

2018-06-14

The calanoid copepod Acartia tonsa is a reference species in standardized ecotoxicology bioassay. Despite this interest, there is a lack of knowledge on molecular responses of A. tonsa to contaminants. We generated a de novo assembled transcriptome of A. tonsa exposed 4 days to 8.5 and 17 mg/L nickel nanoparticles (NiNPs), which have been shown to reduce egg hatching success and larval survival but had no effects on the adults. Aims of our study were to 1) improve the knowledge on the molecular responses of A. tonsa copepod and 2) increase the genomic resources of this copepod for further identification of potential biomarkers of NP exposure. The de novo assembled transcriptome of A. tonsa consisted of 53,619 unigenes, which were further annotated to nr, GO, KOG and KEGG databases. In particular, most unigenes were assigned to Metabolic and Cellular processes (34-45%) GO terms, and to Human disease (28%) and Organismal systems (23%) KEGG categories. Comparison among treatments showed that 373 unigenes were differentially expressed in A. tonsa exposed to NiNPs at 8.5 and 17 mg/L, with respect to control. Most of these genes were downregulated and took part in ribosome biogenesis, translation and protein turnover, thus suggesting that NiNPs could affect the copepod ribosome synthesis machinery and functioning. Overall, our study highlights the potential of toxicogenomic approach in gaining more mechanistic and functional information about the mode of action of emerging compounds on marine organisms, for biomarker discovering in crustaceans. Copyright © 2018 Elsevier Ltd. All rights reserved.

Transcriptomic responses to ocean acidification in larval sea urchins from a naturally variable pH environment.

PubMed

Evans, Tyler G; Chan, Francis; Menge, Bruce A; Hofmann, Gretchen E

2013-03-01

Some marine ecosystems already experience natural declines in pH approximating those predicted with future anthropogenic ocean acidification (OA), the decline in seawater pH caused by the absorption of atmospheric CO2 . The molecular mechanisms that allow organisms to inhabit these low pH environments, particularly those building calcium carbonate skeletons, are unknown. Also uncertain is whether an enhanced capacity to cope with present day pH variation will confer resistance to future OA. To address these issues, we monitored natural pH dynamics within an intertidal habitat in the Northeast Pacific, demonstrating that upwelling exposes resident species to pH regimes not predicted to occur elsewhere until 2100. Next, we cultured the progeny of adult purple sea urchins (Strongylocentrotus purpuratus) collected from this region in CO2 -acidified seawater representing present day and near future ocean scenarios and monitored gene expression using transcriptomics. We hypothesized that persistent exposure to upwelling during evolutionary history will have selected for increased pH tolerance in this population and that their transcriptomic response to low pH seawater would provide insight into mechanisms underlying pH tolerance in a calcifying species. Resulting expression patterns revealed two important trends. Firstly, S. purpuratus larvae may alter the bioavailability of calcium and adjust skeletogenic pathways to sustain calcification in a low pH ocean. Secondly, larvae use different strategies for coping with different magnitudes of pH stress: initiating a robust transcriptional response to present day pH regimes but a muted response to near future conditions. Thus, an enhanced capacity to cope with present day pH variation may not translate into success in future oceans. © 2013 Blackwell Publishing Ltd.

Mitochondrial Dysfunction, Disruption of F-Actin Polymerization, and Transcriptomic Alterations in Zebrafish Larvae Exposed to Trichloroethylene.

PubMed

Wirbisky, Sara E; Damayanti, Nur P; Mahapatra, Cecon T; Sepúlveda, Maria S; Irudayaraj, Joseph; Freeman, Jennifer L

2016-02-15

Trichloroethylene (TCE) is primarily used as an industrial degreasing agent and has been in use since the 1940s. TCE is released into the soil, surface, and groundwater. From an environmental and regulatory standpoint, more than half of Superfund hazardous waste sites on the National Priority List are contaminated with TCE. Occupational exposure to TCE occurs primarily via inhalation, while environmental TCE exposure also occurs through ingestion of contaminated drinking water. Current literature links TCE exposure to various adverse health effects including cardiovascular toxicity. Current studies aiming to address developmental cardiovascular toxicity utilized rodent and avian models, with the majority of studies using relatively higher parts per million (mg/L) doses. In this study, to further investigate developmental cardiotoxicity of TCE, zebrafish embryos were treated with 0, 10, 100, or 500 parts per billion (ppb; μg/L) TCE during embryogenesis and/or through early larval stages. After the appropriate exposure period, angiogenesis, F-actin, and mitochondrial function were assessed. A significant dose-response decrease in angiogenesis, F-actin, and mitochondrial function was observed. To further complement this data, a transcriptomic profile of zebrafish larvae was completed to identify gene alterations associated with the 10 ppb TCE exposure. Results from the transcriptomic data revealed that embryonic TCE exposure caused significant changes in genes associated with cardiovascular disease, cancer, and organismal injury and abnormalities with a number of targets in the FAK signaling pathway. Overall, results from our study support TCE as a developmental cardiovascular toxicant, provide molecular targets and pathways for investigation in future studies, and indicate a need for continued priority for environmental regulation.

Cathepsin Gene Family Reveals Transcriptome Patterns Related to the Infective Stages of the Salmon Louse Caligus rogercresseyi

PubMed Central

Maldonado-Aguayo, Waleska; Chávez-Mardones, Jacqueline; Gonçalves, Ana Teresa; Gallardo-Escárate, Cristian

2015-01-01

Cathepsins are proteases involved in the ability of parasites to overcome and/or modulate host defenses so as to complete their own lifecycle. However, the mechanisms underlying this ability of cathepsins are still poorly understood. One excellent model for identifying and exploring the molecular functions of cathepsins is the marine ectoparasitic copepod Caligus rogercresseyi that currently affects the Chilean salmon industry. Using high-throughput transcriptome sequencing, 56 cathepsin-like sequences were found distributed in five cysteine protease groups (B, F, L, Z, and S) as well as in an aspartic protease group (D). Ontogenic transcriptome analysis evidenced that L cathepsins were the most abundant during the lifecycle, while cathepsins B and K were mostly expressed in the larval stages and adult females, thus suggesting participation in the molting processes and embryonic development, respectively. Interestingly, a variety of cathepsins from groups Z, L, D, B, K, and S were upregulated in the infective stage of copepodid, corroborating the complexity of the processes involved in the parasitic success of this copepod. Putative functional roles of cathepsins were conjectured based on the differential expressions found and on roles previously described in other phylogenetically related species. Moreover, 140 single nucleotide polymorphisms (SNP) were identified in transcripts annotated for cysteine and aspartic proteases located into untranslated regions, or the coding region. This study reports for the first time the presence of cathepsin-like genes and differential expressions throughout a copepod lifecycle. The identification of cathepsins together with functional validations represents a valuable strategy for pinpointing target molecules that could be used in the development of new delousing drugs or vaccines against C. rogercresseyi. PMID:25923525

Cathepsin Gene Family Reveals Transcriptome Patterns Related to the Infective Stages of the Salmon Louse Caligus rogercresseyi.

PubMed

Maldonado-Aguayo, Waleska; Chávez-Mardones, Jacqueline; Gonçalves, Ana Teresa; Gallardo-Escárate, Cristian

2015-01-01

Cathepsins are proteases involved in the ability of parasites to overcome and/or modulate host defenses so as to complete their own lifecycle. However, the mechanisms underlying this ability of cathepsins are still poorly understood. One excellent model for identifying and exploring the molecular functions of cathepsins is the marine ectoparasitic copepod Caligus rogercresseyi that currently affects the Chilean salmon industry. Using high-throughput transcriptome sequencing, 56 cathepsin-like sequences were found distributed in five cysteine protease groups (B, F, L, Z, and S) as well as in an aspartic protease group (D). Ontogenic transcriptome analysis evidenced that L cathepsins were the most abundant during the lifecycle, while cathepsins B and K were mostly expressed in the larval stages and adult females, thus suggesting participation in the molting processes and embryonic development, respectively. Interestingly, a variety of cathepsins from groups Z, L, D, B, K, and S were upregulated in the infective stage of copepodid, corroborating the complexity of the processes involved in the parasitic success of this copepod. Putative functional roles of cathepsins were conjectured based on the differential expressions found and on roles previously described in other phylogenetically related species. Moreover, 140 single nucleotide polymorphisms (SNP) were identified in transcripts annotated for cysteine and aspartic proteases located into untranslated regions, or the coding region. This study reports for the first time the presence of cathepsin-like genes and differential expressions throughout a copepod lifecycle. The identification of cathepsins together with functional validations represents a valuable strategy for pinpointing target molecules that could be used in the development of new delousing drugs or vaccines against C. rogercresseyi.

Effects of the vertically transmitted microsporidian Facilispora margolisi and the parasiticide emamectin benzoate on salmon lice (Lepeophtheirus salmonis).

PubMed

Poley, Jordan D; Sutherland, Ben J G; Fast, Mark D; Koop, Ben F; Jones, Simon R M

2017-08-17

Microsporidia are highly specialized, parasitic fungi that infect a wide range of eukaryotic hosts from all major taxa. Infections cause a variety of damaging effects on host physiology from increased stress to death. The microsporidian Facilispora margolisi infects the Pacific salmon louse (Lepeophtheirus salmonis oncorhynchi), an economically and ecologically important ectoparasitic copepod that can impact wild and cultured salmonids. Vertical transmission of F. margolisi was demonstrated by using PCR and in situ hybridization to identify and localize microsporidia in female L. salmonis and their offspring. Spores and developmental structures of F. margolisi were identified in 77% of F 1 generation copepods derived from infected females while offspring from uninfected females all tested negative for the microsporidia. The transcriptomic response of the salmon louse to F. margolisi was profiled at both the copepodid larval stage and the pre-adult stage using microarray technology. Infected copepodids differentially expressed 577 transcripts related to stress, ATP generation and structural components of muscle and cuticle. The infection also impacted the response of the copepodid to the parasiticide emamectin benzoate (EMB) at a low dose of 1.0 ppb for 24 h. A set of 48 transcripts putatively involved in feeding and host immunomodulation were up to 8-fold underexpressed in the F. margolisi infected copepodids treated with EMB compared with controls or either stressor alone. Additionally, these infected lice treated with EMB also overexpressed 101 transcripts involved in stress resistance and signalling compared to the other groups. In contrast, infected pre-adult lice did not display a stress response, suggesting a decrease in microsporidian virulence associated with lice maturity. Furthermore, copepodid infectivity and moulting was not affected by the microsporidian infection. This study demonstrated that F. margolisi is transmitted vertically between salmon louse generations and that biological impacts of infection differ depending on the stage of the copepod host. The infection caused significant perturbations of larval transcriptomes and therefore must be considered in future studies in which impacts to host development and environmental factors are assessed. Fitness impacts are probably minor, although the interaction between pesticide exposure and microsporidian infection merits further study.

Influence of prior residents on settlement preferences in the anemonefish, Premnas biaculeatus

NASA Astrophysics Data System (ADS)

Dixson, Danielle L.; Jones, Geoffrey P.

2018-06-01

Settlement preferences play a critical role in the successful transition from pelagic larvae to benthic juveniles for many coral reef organisms. Reef fish larvae are capable of recognizing and behaviorally responding to a variety of sensory cues when assessing settlement site locations. The presence of resident conspecifics for site attached coral reef fishes could indicate a quality location, but may result in negative interactions through aggression from already-established individuals. For anemonefishes, where space on a sea anemone is limited and breeding is restricted to one adult pair, settlement preferences may depend on the number and sex of the occupants. Here we undertook both aquarium-based olfactory trials and a field experiment to determine the role resident anemonefish individuals have on sea anemone site selection in the spine cheek anemonefish, Premnas biaculeatus. We show larvae are able to identify the occupant saturation state and sex of the resident occupants based on chemical cues alone, with larvae preferring the chemical cues produced by a single male to a single female, the single fish to an empty sea anemone, and an empty sea anemone to a sea anemone containing an adult pair. These behavioral preferences were reflected in the settlement preferences of larvae when assessed in the natural environment. We hypothesize that the ability of resident fish to evict incoming larvae combined with the selective pressure on larvae to locate an ideal habitat has resulted in the larval ability to accurately identify habitat where settlement and future breeding opportunities are most likely achieved.

Isolation by distance across the Hawaiian Archipelago in the reef-building coral Porites lobata.

PubMed

Polato, Nicholas R; Concepcion, Gregory T; Toonen, Robert J; Baums, Iliana B

2010-11-01

There is an ongoing debate on the scale of pelagic larval dispersal in promoting connectivity among populations of shallow, benthic marine organisms. The linearly arranged Hawaiian Islands are uniquely suited to study scales of population connectivity and have been used extensively as a natural laboratory in terrestrial systems. Here, we focus on Hawaiian populations of the lobe coral Porites lobata, an ecosystem engineer of shallow reefs throughout the Pacific. Patterns of recent gene flow and population structure in P. lobata samples (n = 318) from two regions, the Hawaiian Islands (n = 10 sites) and from their nearest neighbour Johnston Atoll, were analysed with nine microsatellite loci. Despite its massive growth form, ∼ 6% of the samples from both regions were the product of asexual reproduction via fragmentation. Cluster analysis and measures of genetic differentiation indicated that P. lobata from the Hawaiian Islands are strongly isolated from those on Johnston Atoll (F(ST)  = 0.311; P < 0.001), with the descendants of recent migrants (n = 6) being clearly identifiable. Within the Hawaiian Islands, P. lobata conforms to a pattern of isolation by distance. Here, over 37% (P = 0.001) of the variation in genetic distance was explained by geographical distance. This pattern indicates that while the majority of ongoing gene flow in Hawaiian P. lobata occurs among geographically proximate reefs, inter-island distances are insufficient to generate strong population structure across the archipelago. © 2010 Blackwell Publishing Ltd.

Identification of long non-coding RNAs in two anthozoan species and their possible implications for coral bleaching.

PubMed

Huang, Chen; Morlighem, Jean-Étienne R L; Cai, Jing; Liao, Qiwen; Perez, Carlos Daniel; Gomes, Paula Braga; Guo, Min; Rádis-Baptista, Gandhi; Lee, Simon Ming-Yuen

2017-07-13

Long non-coding RNAs (lncRNAs) have been shown to play regulatory roles in a diverse range of biological processes and are associated with the outcomes of various diseases. The majority of studies about lncRNAs focus on model organisms, with lessened investigation in non-model organisms to date. Herein, we have undertaken an investigation on lncRNA in two zoanthids (cnidarian): Protolpalythoa varibilis and Palythoa caribaeorum. A total of 11,206 and 13,240 lncRNAs were detected in P. variabilis and P. caribaeorum transcriptome, respectively. Comparison using NONCODE database indicated that the majority of these lncRNAs is taxonomically species-restricted with no identifiable orthologs. Even so, we found cases in which short regions of P. caribaeorum's lncRNAs were similar to vertebrate species' lncRNAs, and could be associated with lncRNA conserved regulatory functions. Consequently, some high-confidence lncRNA-mRNA interactions were predicted based on such conserved regions, therefore revealing possible involvement of lncRNAs in posttranscriptional processing and regulation in anthozoans. Moreover, investigation of differentially expressed lncRNAs, in healthy colonies and colonial individuals undergoing natural bleaching, indicated that some up-regulated lncRNAs in P. caribaeorum could posttranscriptionally regulate the mRNAs encoding proteins of Ras-mediated signal transduction pathway and components of innate immune-system, which could contribute to the molecular response of coral bleaching.

Gene duplications are extensive and contribute significantly to the toxic proteome of nematocysts isolated from Acropora digitifera (Cnidaria: Anthozoa: Scleractinia).

PubMed

Gacesa, Ranko; Chung, Ray; Dunn, Simon R; Weston, Andrew J; Jaimes-Becerra, Adrian; Marques, Antonio C; Morandini, André C; Hranueli, Daslav; Starcevic, Antonio; Ward, Malcolm; Long, Paul F

2015-10-13

Gene duplication followed by adaptive selection is a well-accepted process leading to toxin diversification in venoms. However, emergent genomic, transcriptomic and proteomic evidence now challenges this role to be at best equivocal to other processess . Cnidaria are arguably the most ancient phylum of the extant metazoa that are venomous and such provide a definitive ancestral anchor to examine the evolution of this trait. Here we compare predicted toxins from the translated genome of the coral Acropora digitifera to putative toxins revealed by proteomic analysis of soluble proteins discharged from nematocysts, to determine the extent to which gene duplications contribute to venom innovation in this reef-building coral species. A new bioinformatics tool called HHCompare was developed to detect potential gene duplications in the genomic data, which is made freely available ( https://github.com/rgacesa/HHCompare ). A total of 55 potential toxin encoding genes could be predicted from the A. digitifera genome, of which 36 (65 %) had likely arisen by gene duplication as evinced using the HHCompare tool and verified using two standard phylogeny methods. Surprisingly, only 22 % (12/55) of the potential toxin repertoire could be detected following rigorous proteomic analysis, for which only half (6/12) of the toxin proteome could be accounted for as peptides encoded by the gene duplicates. Biological activities of these toxins are dominatedby putative phospholipases and toxic peptidases. Gene expansions in A. digitifera venom are the most extensive yet described in any venomous animal, and gene duplication plays a significant role leading to toxin diversification in this coral species. Since such low numbers of toxins were detected in the proteome, it is unlikely that the venom is evolving rapidly by prey-driven positive natural selection. Rather we contend that the venom has a defensive role deterring predation or harm from interspecific competition and overgrowth by fouling organisms. Factors influencing translation of toxin encoding genes perhaps warrants more profound experimental consideration.

Adaptations to Endosymbiosis in a Cnidarian-Dinoflagellate Association: Differential Gene Expression and Specific Gene Duplications

PubMed Central

Magnone, Virginie; Allemand, Denis; Furla, Paola; Sabourault, Cécile

2011-01-01

Trophic endosymbiosis between anthozoans and photosynthetic dinoflagellates forms the key foundation of reef ecosystems. Dysfunction and collapse of symbiosis lead to bleaching (symbiont expulsion), which is responsible for the severe worldwide decline of coral reefs. Molecular signals are central to the stability of this partnership and are therefore closely related to coral health. To decipher inter-partner signaling, we developed genomic resources (cDNA library and microarrays) from the symbiotic sea anemone Anemonia viridis. Here we describe differential expression between symbiotic (also called zooxanthellate anemones) or aposymbiotic (also called bleached) A. viridis specimens, using microarray hybridizations and qPCR experiments. We mapped, for the first time, transcript abundance separately in the epidermal cell layer and the gastrodermal cells that host photosynthetic symbionts. Transcriptomic profiles showed large inter-individual variability, indicating that aposymbiosis could be induced by different pathways. We defined a restricted subset of 39 common genes that are characteristic of the symbiotic or aposymbiotic states. We demonstrated that transcription of many genes belonging to this set is specifically enhanced in the symbiotic cells (gastroderm). A model is proposed where the aposymbiotic and therefore heterotrophic state triggers vesicular trafficking, whereas the symbiotic and therefore autotrophic state favors metabolic exchanges between host and symbiont. Several genetic pathways were investigated in more detail: i) a key vitamin K–dependant process involved in the dinoflagellate-cnidarian recognition; ii) two cnidarian tissue-specific carbonic anhydrases involved in the carbon transfer from the environment to the intracellular symbionts; iii) host collagen synthesis, mostly supported by the symbiotic tissue. Further, we identified specific gene duplications and showed that the cnidarian-specific isoform was also up-regulated both in the symbiotic state and in the gastroderm. Our results thus offer new insight into the inter-partner signaling required for the physiological mechanisms of the symbiosis that is crucial for coral health. PMID:21811417

Transcriptomic Responses of Atlantic Salmon (Salmo salar) to Environmental Enrichment during Juvenile Rearing

PubMed Central

Evans, Melissa L.; Hori, Tiago S.; Rise, Matthew L.; Fleming, Ian A.

2015-01-01

Captive rearing programs (hatcheries) are often used in conservation and management efforts for at-risk salmonid fish populations. However, hatcheries typically rear juveniles in environments that contrast starkly with natural conditions, which may lead to phenotypic and/or genetic changes that adversely affect the performance of juveniles upon their release to the wild. Environmental enrichment has been proposed as a mechanism to improve the efficacy of population restoration efforts from captive-rearing programs; in this study, we examine the influence of environmental enrichment during embryo and yolk-sac larval rearing on the transcriptome of Atlantic salmon (Salmo salar). Full siblings were reared in either a hatchery environment devoid of structure or an environment enriched with gravel substrate. At the end of endogenous feeding by juveniles, we examined patterns of gene transcript abundance in head tissues using the cGRASP-designed Agilent 4×44K microarray. Significance analysis of microarrays (SAM) indicated that 808 genes were differentially transcribed between the rearing environments and a total of 184 gene ontological (GO) terms were over- or under-represented in this gene list, several associated with mitosis/cell cycle and muscle and heart development. There were also pronounced differences among families in the degree of transcriptional response to rearing environment enrichment, suggesting that gene-by-environment effects, possibly related to parental origin, could influence the efficacy of enrichment interventions. PMID:25742646

Transcriptomic responses of Atlantic salmon (Salmo salar) to environmental enrichment during juvenile rearing.

PubMed

Evans, Melissa L; Hori, Tiago S; Rise, Matthew L; Fleming, Ian A

2015-01-01

Captive rearing programs (hatcheries) are often used in conservation and management efforts for at-risk salmonid fish populations. However, hatcheries typically rear juveniles in environments that contrast starkly with natural conditions, which may lead to phenotypic and/or genetic changes that adversely affect the performance of juveniles upon their release to the wild. Environmental enrichment has been proposed as a mechanism to improve the efficacy of population restoration efforts from captive-rearing programs; in this study, we examine the influence of environmental enrichment during embryo and yolk-sac larval rearing on the transcriptome of Atlantic salmon (Salmo salar). Full siblings were reared in either a hatchery environment devoid of structure or an environment enriched with gravel substrate. At the end of endogenous feeding by juveniles, we examined patterns of gene transcript abundance in head tissues using the cGRASP-designed Agilent 4×44K microarray. Significance analysis of microarrays (SAM) indicated that 808 genes were differentially transcribed between the rearing environments and a total of 184 gene ontological (GO) terms were over- or under-represented in this gene list, several associated with mitosis/cell cycle and muscle and heart development. There were also pronounced differences among families in the degree of transcriptional response to rearing environment enrichment, suggesting that gene-by-environment effects, possibly related to parental origin, could influence the efficacy of enrichment interventions.

The Transcriptome of the Zoanthid Protopalythoa variabilis (Cnidaria, Anthozoa) Predicts a Basal Repertoire of Toxin-like and Venom-Auxiliary Polypeptides

PubMed Central

Huang, Chen; Morlighem, Jean-Étienne RL; Zhou, Hefeng; Lima, Érica P; Gomes, Paula B; Cai, Jing; Lou, Inchio; Pérez, Carlos D; Lee, Simon Ming; Rádis-Baptista, Gandhi

2016-01-01

Abstract Protopalythoa is a zoanthid that, together with thousands of predominantly marine species, such as hydra, jellyfish, and sea anemones, composes the oldest eumetazoan phylum, i.e., the Cnidaria. Some of these species, such as sea wasps and sea anemones, are highly venomous organisms that can produce deadly toxins for preying, for defense or for territorial disputes. Despite the fact that hundreds of organic and polypeptide toxins have been characterized from sea anemones and jellyfish, practically nothing is known about the toxin repertoire in zoanthids. Here, based on a transcriptome analysis of the zoanthid Protopalythoa variabilis, numerous predicted polypeptides with canonical venom protein features are identified. These polypeptides comprise putative proteins from different toxin families: neurotoxic peptides, hemostatic and hemorrhagic toxins, membrane-active (pore-forming) proteins, protease inhibitors, mixed-function venom enzymes, and venom auxiliary proteins. The synthesis and functional analysis of two of these predicted toxin products, one related to the ShK/Aurelin family and the other to a recently discovered anthozoan toxin, displayed potent in vivo neurotoxicity that impaired swimming in larval zebrafish. Altogether, the complex array of venom-related transcripts that are identified in P. variabilis, some of which are first reported in Cnidaria, provides novel insight into the toxin distribution among species and might contribute to the understanding of composition and evolution of venom polypeptides in toxiferous animals. PMID:27566758

Transcriptome profiling analysis reveals the role of latrophilin in controlling development, reproduction and insecticide susceptibility in Tribolium castaneum.

PubMed

Gao, Shanshan; Xiong, Wenfeng; Wei, Luting; Liu, Juanjuan; Liu, Xing; Xie, Jia; Song, Xiaowen; Bi, Jingxiu; Li, Bin

2018-06-01

Latrophilin of Tribolium castaneum (Tclph) has been reported to play crucial roles in growth, development and reproduction. However, the regulatory mechanism of Tclph associated with these physiology processes is unknown. Thus, the global transcriptome profiles between RNAi treated (ds-Tclph) and control larvae of T. castaneum were analyzed by RNA-sequencing. Totally, 274 differentially expressed genes (DEGs) were identified between the ds-Tclph and control samples. These DEGs were classified into 42 GO functional groups, including developmental process, reproduction and stress response. The results indicated that knockdown of Tclph disturbed the antioxidant activity process, and partially inhibited the serine protease (SP) and lipase signaling pathways to regulate the development and reproduction as well as the decreasing of the stress response in T. castaneum. Additionally, knockdown of Tclph suppressed IMD immunity pathways which likely modulated the effects of Tclph on stress response. Interestingly, CSPs, ESTs, CYPs, AOXs and BGs were significantly down-regulated in ds-Tclph larvae, implying that they cooperated with Tclph to reduce the activity of cellular metabolism system. FMOs was up-regulated in ds-Tclph insects suggested it may be involved in detoxifying alkaloid of insect metabolism system. These results implied that Tclph participated in phase 0, I and II cellular detoxification. Furthermore, RNAi against Tclph increased larval susceptibility to carbamates and organophosphates insecticides, supporting that Tclph was indeed involved into the insecticide susceptibility in T. castaneum.

Cross-species comparison of the gut: Differential gene expression sheds light on biological differences in closely related tenebrionids.

PubMed

Oppert, Brenda; Perkin, Lindsey; Martynov, Alexander G; Elpidina, Elena N

2018-04-01

The gut is one of the primary interfaces between an insect and its environment. Understanding gene expression profiles in the insect gut can provide insight into interactions with the environment as well as identify potential control methods for pests. We compared the expression profiles of transcripts from the gut of larval stages of two coleopteran insects, Tenebrio molitor and Tribolium castaneum. These tenebrionids have different life cycles, varying in the duration and number of larval instars. T. castaneum has a sequenced genome and has been a model for coleopterans, and we recently obtained a draft genome for T. molitor. We assembled gut transcriptome reads from each insect to their respective genomes and filtered mapped reads to RPKM>1, yielding 11,521 and 17,871 genes in the T. castaneum and T. molitor datasets, respectively. There were identical GO terms in each dataset, and enrichment analyses also identified shared GO terms. From these datasets, we compiled an ortholog list of 6907 genes; 45% of the total assembled reads from T. castaneum were found in the top 25 orthologs, but only 27% of assembled reads were found in the top 25 T. molitor orthologs. There were 2281 genes unique to T. castaneum, and 2088 predicted genes unique to T. molitor, although improvements to the T. molitor genome will likely reduce these numbers as more orthologs are identified. We highlight a few unique genes in T. castaneum or T. molitor that may relate to distinct biological functions. A large number of putative genes expressed in the larval gut with uncharacterized functions (36 and 68% from T. castaneum and T. molitor, respectively) support the need for further research. These data are the first step in building a comprehensive understanding of the physiology of the gut in tenebrionid insects, illustrating commonalities and differences that may be related to speciation and environmental adaptation. Published by Elsevier Ltd.

RIP2 Is a Critical Regulator for NLRs Signaling and MHC Antigen Presentation but Not for MAPK and PI3K/Akt Pathways.

PubMed

Wu, Xiao Man; Chen, Wen Qin; Hu, Yi Wei; Cao, Lu; Nie, Pin; Chang, Ming Xian

2018-01-01

RIP2 is an adaptor protein which is essential for the activation of NF-κB and NOD1- and NOD2-dependent signaling. Although NOD-RIP2 axis conservatively existed in the teleost, the function of RIP2 was only reported in zebrafish, goldfish, and rainbow trout in vitro . Very little is known about the role and mechanisms of piscine NOD-RIP2 axis in vivo . Our previous study showed the protective role of zebrafish NOD1 in larval survival through CD44a-mediated activation of PI3K-Akt signaling. In this study, we examined whether RIP2 was required for larval survival with or without pathogen infection, and determined the signaling pathways modulated by RIP2. Based on our previous report and the present study, our data demonstrated that NOD1-RIP2 axis was important for larval survival in the early ontogenesis. Similar to NOD1, RIP2 deficiency significantly affected immune system processes. The significantly enriched pathways were mainly involved in immune system, such as "Antigen processing and presentation" and "NOD-like receptor signaling pathway" and so on. Furthermore, both transcriptome analysis and qRT-PCR revealed that RIP2 was a critical regulator for expression of NLRs (NOD-like receptors) and those genes involved in MHC antigen presentation. Different from NOD1, the present study showed that NOD1, but not RIP2 deficiency significantly impaired protein levels of MAPK pathways. Although RIP2 deficiency also significantly impaired the expression of CD44a, the downstream signaling of CD44a-Lck-PI3K-Akt pathway remained unchanged. Collectively, our works highlight the similarity and discrepancy of NOD1 and RIP2 in the regulation of immune signaling pathways in the zebrafish early ontogenesis, and confirm the crucial role of RIP2 in NLRs signaling and MHC antigen presentation, but not for MAPK and PI3K/Akt pathways.

A Transcriptomic Analysis of Echinococcus granulosus Larval Stages: Implications for Parasite Biology and Host Adaptation

PubMed Central

Parkinson, John; Wasmuth, James D.; Salinas, Gustavo; Bizarro, Cristiano V.; Sanford, Chris; Berriman, Matthew; Ferreira, Henrique B.; Zaha, Arnaldo; Blaxter, Mark L.; Maizels, Rick M.; Fernández, Cecilia

2012-01-01

Background The cestode Echinococcus granulosus - the agent of cystic echinococcosis, a zoonosis affecting humans and domestic animals worldwide - is an excellent model for the study of host-parasite cross-talk that interfaces with two mammalian hosts. To develop the molecular analysis of these interactions, we carried out an EST survey of E. granulosus larval stages. We report the salient features of this study with a focus on genes reflecting physiological adaptations of different parasite stages. Methodology/Principal Findings We generated ∼10,000 ESTs from two sets of full-length enriched libraries (derived from oligo-capped and trans-spliced cDNAs) prepared with three parasite materials: hydatid cyst wall, larval worms (protoscoleces), and pepsin/H+-activated protoscoleces. The ESTs were clustered into 2700 distinct gene products. In the context of the biology of E. granulosus, our analyses reveal: (i) a diverse group of abundant long non-protein coding transcripts showing homology to a middle repetitive element (EgBRep) that could either be active molecular species or represent precursors of small RNAs (like piRNAs); (ii) an up-regulation of fermentative pathways in the tissue of the cyst wall; (iii) highly expressed thiol- and selenol-dependent antioxidant enzyme targets of thioredoxin glutathione reductase, the functional hub of redox metabolism in parasitic flatworms; (iv) candidate apomucins for the external layer of the tissue-dwelling hydatid cyst, a mucin-rich structure that is critical for survival in the intermediate host; (v) a set of tetraspanins, a protein family that appears to have expanded in the cestode lineage; and (vi) a set of platyhelminth-specific gene products that may offer targets for novel pan-platyhelminth drug development. Conclusions/Significance This survey has greatly increased the quality and the quantity of the molecular information on E. granulosus and constitutes a valuable resource for gene prediction on the parasite genome and for further genomic and proteomic analyses focused on cestodes and platyhelminths. PMID:23209850

A novel highly divergent protein family identified from a viviparous insect by RNA-seq analysis: a potential target for tsetse fly-specific abortifacients.

PubMed

Benoit, Joshua B; Attardo, Geoffrey M; Michalkova, Veronika; Krause, Tyler B; Bohova, Jana; Zhang, Qirui; Baumann, Aaron A; Mireji, Paul O; Takáč, Peter; Denlinger, David L; Ribeiro, Jose M; Aksoy, Serap

2014-04-01

In tsetse flies, nutrients for intrauterine larval development are synthesized by the modified accessory gland (milk gland) and provided in mother's milk during lactation. Interference with at least two milk proteins has been shown to extend larval development and reduce fecundity. The goal of this study was to perform a comprehensive characterization of tsetse milk proteins using lactation-specific transcriptome/milk proteome analyses and to define functional role(s) for the milk proteins during lactation. Differential analysis of RNA-seq data from lactating and dry (non-lactating) females revealed enrichment of transcripts coding for protein synthesis machinery, lipid metabolism and secretory proteins during lactation. Among the genes induced during lactation were those encoding the previously identified milk proteins (milk gland proteins 1-3, transferrin and acid sphingomyelinase 1) and seven new genes (mgp4-10). The genes encoding mgp2-10 are organized on a 40 kb syntenic block in the tsetse genome, have similar exon-intron arrangements, and share regions of amino acid sequence similarity. Expression of mgp2-10 is female-specific and high during milk secretion. While knockdown of a single mgp failed to reduce fecundity, simultaneous knockdown of multiple variants reduced milk protein levels and lowered fecundity. The genomic localization, gene structure similarities, and functional redundancy of MGP2-10 suggest that they constitute a novel highly divergent protein family. Our data indicates that MGP2-10 function both as the primary amino acid resource for the developing larva and in the maintenance of milk homeostasis, similar to the function of the mammalian casein family of milk proteins. This study underscores the dynamic nature of the lactation cycle and identifies a novel family of lactation-specific proteins, unique to Glossina sp., that are essential to larval development. The specificity of MGP2-10 to tsetse and their critical role during lactation suggests that these proteins may be an excellent target for tsetse-specific population control approaches.

Developmental Toxicity of Zinc Oxide Nanoparticles to Zebrafish (Danio rerio): A Transcriptomic Analysis

PubMed Central

Choi, Jin Soo; Kim, Ryeo-Ok; Yoon, Seokjoo

2016-01-01

Zinc oxide nanoparticles (ZnO NPs) are being utilized in an increasing number of fields and commercial applications. While their general toxicity and associated oxidative stress have been extensively studied, the toxicological pathways that they induce in developmental stages are still largely unknown. In this study, the developmental toxicity of ZnO NPs to embryonic/larval zebrafish was investigated. The transcriptional expression profiles induced by ZnO NPs were also investigated to ascertain novel genomic responses related to their specific toxicity pathway. Zebrafish embryos were exposed to 0.01, 0.1, 1, and 10 mg/L ZnO NPs for 96 h post-fertilization. The toxicity of ZnO NPs, based on their Zn concentration, was quite similar to that in embryonic/larval zebrafish exposed to corresponding ZnSO4 concentrations. Pericardial edema and yolk-sac edema were the principal malformations induced by ZnO NPs. Gene-expression profiling using microarrays demonstrated 689 genes that were differentially regulated (fold change >1.5) following exposure to ZnO NPs (498 upregulated, 191 downregulated). Several genes that were differentially regulated following ZnO NP exposure shared similar biological pathways with those observed with ZnSO4 exposure, but six genes (aicda, cyb5d1, edar, intl2, ogfrl2 and tnfsf13b) associated with inflammation and the immune system responded specifically to ZnO NPs (either in the opposite direction or were unchanged in ZnSO4 exposure). Real-time reverse-transcription quantitative polymerase chain reaction confirmed that the responses of these genes to ZnO NPs were significantly different from their response to ZnSO4 exposure. ZnO NPs may affect genes related to inflammation and the immune system, resulting in yolk-sac edema and pericardia edema in embryonic/larval developmental stages. These results will assist in elucidating the mechanisms of toxicity of ZnO NPs during development of zebrafish. PMID:27504894

Coastal Circulation and Sediment Dynamics in War-in-the-Pacific National Historical Park, Guam; measurements of waves, currents, temperature, salinity, and turbidity, June 2007-January 2008

USGS Publications Warehouse

Storlazzi, Curt D.; Presto, M. Katherine; Logan, Joshua B.

2009-01-01

Flow in and around coral reefs affects a number of physical, chemical and biologic processes that influence the health and sustainability of coral reef ecosystems. These range from the residence time of sediment and contaminants to nutrient uptake and larval retention and dispersal. As currents approach a coast they diverge to flow around reef structures, causing high horizontal and vertical shear. This can result in either the rapid advection of material in localized jets, or the retention of material in eddies that form in the lee of bathymetric features. The high complexity and diversity both within and between reefs, in conjunction with past technical restrictions, has limited our understanding of the nature of flow and the resulting flux of physical, chemical, and biologic material in these fragile ecosystems. Sediment, nutrients, and other pollutants from a variety of land-based activities adversely impact many coral reef ecosystems in the U.S. and around the world. These pollutants are transported in surface water runoff, groundwater seepage, and atmospheric fallout into coastal waters, and there is compelling evidence that the sources have increased globally as a result of human-induced changes to watersheds. In Guam, and elsewhere on U.S. high islands in the Pacific and Caribbean, significant changes in the drainage basins due to agriculture, feral grazing, fires, and urbanization have in turn altered the character and volume of land-based pollution released to coral reefs. Terrigenous sediment run-off (and the associated nutrients and contaminants often absorbed to it) and deposition on coral reefs are recognized to potentially have significant impact on coral health by blocking light and inhibiting photosynthesis, directly smothering and abrading coral, and triggering increases in macro algae. Studies that combine information on watershed, surface water- and groundwater-flow, transport and fate of sediment and other pollutants in the reef environment, and their impact on reef health and ecology are essential for effective reef management. Two of the main anthropogenic activities along west-central Guam's coastline that may impact the region's coral reef ecosystems include pollution and coastal land use/development, as discussed in the review by Porter and others (2005). The pollution threats include point-sources, such as municipal wastewater (Northern District, Hagatna, Naval Station Guam, and Agat-Santa Rita Waster Water Treatment Plants), cooling water (Tanguisson Steam and Cabras Power Plants), and numerous storm water, ballast water, and tank bottom draw outfalls; nonpoint sources include septic systems, urban runoff, illegal dumping, and groundwater discharges. Poor land-use practices include development without the use of runoff management measures, increased areal extent of impervious surfaces and decreased extent of vegetative barriers, and recreational off-road vehicle use. Furthermore, feral ungulates and illegal wildfires remove protective vegetative cover and generally result in increased soil erosion. While anthropogenic point-sources have been reduced in many areas due to better management practices, nonpoint sources have either stayed constant or increased. Between 1975 and 1999, it is estimated that Guam lost more than a quarter of its tree cover, and more than 750 wildfires each year have resulted in a greater proportion of badlands and other erosion-prone land surfaces with high erosion rates (Forestry and Soil Resources Division, 1999). Approximately 1.8 square kilometers (km2) of Asan Bay, west-central Guam, lies within the National Park Service's (NPS) War-in-the-Pacific National Historical Park's (WAPA) Asan Unit; the bay is the sink for material coming out of the Asan watershed. Anthropogenic modifications of the watersheds adjacent to Asan Bay, which include intentionally-set wildfires, construction, and agriculture (Minton, 2005), are believed to have increased over the past 25

Maternal Rest/Nrsf Regulates Zebrafish Behavior through snap25a/b

PubMed Central

Moravec, Cara E.; Samuel, John; Weng, Wei; Wood, Ian C.

2016-01-01

During embryonic development, regulation of gene expression is key to creating the many subtypes of cells that an organism needs throughout its lifetime. Recent work has shown that maternal genetics and environmental factors have lifelong consequences on diverse processes ranging from immune function to stress responses. The RE1-silencing transcription factor (Rest) is a transcriptional repressor that interacts with chromatin-modifying complexes to repress transcription of neural-specific genes during early development. Here we show that in zebrafish, maternally supplied rest regulates expression of target genes during larval development and has lifelong impacts on behavior. Larvae deprived of maternal rest are hyperactive and show atypical spatial preferences. Adult male fish deprived of maternal rest present with atypical spatial preferences in a novel environment assay. Transcriptome sequencing revealed 158 genes that are repressed by maternal rest in blastula stage embryos. Furthermore, we found that maternal rest is required for target gene repression until at least 6 dpf. Importantly, disruption of the RE1 sites in either snap25a or snap25b resulted in behaviors that recapitulate the hyperactivity phenotype caused by absence of maternal rest. Both maternal rest mutants and snap25a RE1 site mutants have altered primary motor neuron architecture that may account for the enhanced locomotor activity. These results demonstrate that maternal rest represses snap25a/b to modulate larval behavior and that early Rest activity has lifelong behavioral impacts. SIGNIFICANCE STATEMENT Maternal factors deposited in the oocyte have well-established roles during embryonic development. We show that, in zebrafish, maternal rest (RE1-silencing transcription factor) regulates expression of target genes during larval development and has lifelong impacts on behavior. The Rest transcriptional repressor interacts with chromatin-modifying complexes to limit transcription of neural genes. We identify several synaptic genes that are repressed by maternal Rest and demonstrate that snap25a/b are key targets of maternal rest that modulate larval locomotor activity. These results reveal that zygotic rest is unable to compensate for deficits in maternally supplied rest and uncovers novel temporal requirements for Rest activity, which has implications for the broad roles of Rest-mediated repression during neural development and in disease states. PMID:27605615

Clonal structure and variable fertilization success in Florida Keys broadcast-spawning corals

NASA Astrophysics Data System (ADS)

Miller, M. W.; Baums, I. B.; Pausch, R. E.; Bright, A. J.; Cameron, C. M.; Williams, D. E.; Moffitt, Z. J.; Woodley, C. M.

2018-03-01

Keystone reef-building corals in the Caribbean are predominantly self-incompatible broadcast spawners and a majority are threatened due to both acute adult mortality and poor recruitment. As population densities decline, concerns about fertilization limitation and effective population size in these species increase and would be further exacerbated by either high clonality or gametic incompatibility of parental genotypes. This study begins to address these concerns for two Caribbean broadcasting species by characterizing clonal structure and quantifying experimental pairwise fertilization success. Orbicella faveolata showed surprisingly high and contrasting levels of clonality between two sampled sites; Acropora palmata was previously known to be highly clonal. Individual pairwise crosses of synchronously spawning genotypes of each species were conducted by combining aliquots of gamete bundles immediately after spawning, and showed high and significant variability in fertilization success. Over half of the individual crosses of O. faveolata and about one-third of A. palmata crosses yielded ≤ 40% fertilization. Total sperm concentration was quantified in only a subset of O. faveolata crosses (range of 1-6 × 107 mL-1), but showed no correlation with fertilization success. We interpret that both parental incompatibility and individual genotypes with low-quality gametes are likely to have contributed to the variable fertilization observed with important implications for conservation. Differential fertilization success implies effective population size may be considerably smaller than hoped and population enhancement efforts need to incorporate many more parental genotypes at the patch scale to ensure successful larval production than indicated by estimates based simply on preserving levels of standing genetic diversity.

Experimental evaluation of imprinting and the role innate preference plays in habitat selection in a coral reef fish.

PubMed

Dixson, Danielle L; Jones, Geoffrey P; Munday, Philip L; Planes, Serge; Pratchett, Morgan S; Thorrold, Simon R

2014-01-01

When facing decisions about where to live, juveniles have a strong tendency to choose habitats similar to where their parents successfully bred. Developing larval fishes can imprint on the chemical cues from their natal habitat. However, to demonstrate that imprinting is ecologically important, it must be shown that settlers respond and distinguish among different imprinted cues, and use imprinting for decisions in natural environments. In addition, the potential role innate preferences play compared to imprinted choices also needs to be examined. As environmental variability increases due to anthropogenic causes these two recognition mechanisms, innate and imprinting, could provide conflicting information. Here we used laboratory rearing and chemical choice experiments to test imprinting in larval anemonefish (Amphiprion percula). Individuals exposed to a variety of benthic habitat or novel olfactory cues as larvae either developed a preference for (spent >50% of their time in the cue) or increased their attraction to (increased preference but did not spend >50% of their time in the cue) the cue when re-exposed as settlers. Results indicate not only the capacity for imprinting but also the ability to adjust innate preferences after early exposure to a chemical cue. To test ecological relevance in the natural system, recruits were collected from anemones and related to their parents, using genetic parentage analysis, providing information on the natal anemone species and the species chosen at settlement. Results demonstrated that recruits did not preferentially return to their natal species, conflicting with laboratory results indicating the importance imprinting might have in habitat recognition.

Estimation of desmosponge (Porifera, Demospongiae) larval settlement rates from short-term recruitment rates: Preliminary experiments

NASA Astrophysics Data System (ADS)

Zea, Sven

1992-09-01

During a study of the spatial and temporal patterns of desmosponge (Porifera, Demospongiae) recruitment on rocky and coral reef habitats of Santa Marta, Colombian Caribbean Sea, preliminary attempts were made to estimate actual settlement rates from short-term (1 to a few days) recruitment censuses. Short-term recruitment rates on black, acrylic plastic plates attached to open, non-cryptic substratum by anchor screws were low and variable (0 5 recruits/plate in 1 2 days, sets of n=5 10 plates), but reflected the depth and seasonal trends found using mid-term (1 to a few months) censusing intervals. Moreover, mortality of recruits during 1 2 day intervals was low (0 12%). Thus, short-term censusing intervals can be used to estimate actual settlement rates. To be able to make statistical comparisons, however, it is necessary to increase the number of recruits per census by pooling data of n plates per set, and to have more than one set per site or treatment.

Full allogeneic fusion of embryos in a holothuroid echinoderm.

PubMed

Gianasi, Bruno L; Hamel, Jean-François; Mercier, Annie

2018-05-30

Whole-body chimaeras (organisms composed of genetically distinct cells) have been directly observed in modular/colonial organisms (e.g. corals, sponges, ascidians); whereas in unitary deuterostosmes (including mammals) they have only been detected indirectly through molecular analysis. Here, we document for the first time the step-by-step development of whole-body chimaeras in the holothuroid Cucumaria frondosa , a unitary deuterostome belonging to the phylum Echinodermata. To the best of our knowledge, this is the most derived unitary metazoan in which direct investigation of zygote fusibility has been undertaken. Fusion occurred among hatched blastulae, never during earlier (unhatched) or later (larval) stages. The fully fused chimaeric propagules were two to five times larger than non-chimaeric embryos. Fusion was positively correlated with propagule density and facilitated by the natural tendency of early embryos to agglomerate. The discovery of natural chimaerism in a unitary deuterostome that possesses large externally fertilized eggs provides a framework to explore key aspects of evolutionary biology, histocompatibility and cell transplantation in biomedical research. © 2018 The Author(s).

Kin-Aggregations Explain Chaotic Genetic Patchiness, a Commonly Observed Genetic Pattern, in a Marine Fish.

PubMed

Selwyn, Jason D; Hogan, J Derek; Downey-Wall, Alan M; Gurski, Lauren M; Portnoy, David S; Heath, Daniel D

2016-01-01

The phenomenon of chaotic genetic patchiness is a pattern commonly seen in marine organisms, particularly those with demersal adults and pelagic larvae. This pattern is usually associated with sweepstakes recruitment and variable reproductive success. Here we investigate the biological underpinnings of this pattern in a species of marine goby Coryphopterus personatus. We find that populations of this species show tell-tale signs of chaotic genetic patchiness including: small, but significant, differences in genetic structure over short distances; a non-equilibrium or "chaotic" pattern of differentiation among locations in space; and within locus, within population deviations from the expectations of Hardy-Weinberg equilibrium (HWE). We show that despite having a pelagic larval stage, and a wide distribution across Caribbean coral reefs, this species forms groups of highly related individuals at small spatial scales (<10 metres). These spatially clustered family groups cause the observed deviations from HWE and local population differentiation, a finding that is rarely demonstrated, but could be more common than previously thought.

Nanoscale Transforming Mineral Phases in Fresh Nacre

DOE PAGES

DeVol, Ross T.; Sun, Chang-Yu; Marcus, Matthew A.; ...

2015-09-24

Nacre, or mother-of-pearl, the iridescent inner layer of many mollusk shells, is a biomineral lamellar composite of aragonite (CaCO 3) and organic sheets. Biomineralization frequently occurs via transient amorphous precursor phases, crystallizing into the final stable biomineral. In nacre, despite extensive attempts, amorphous calcium carbonate (ACC) precursors have remained elusive. They were inferred from non-nacre-forming larval shells, or from a residue of amorphous material surrounding mature gastropod nacre tablets, and have only once been observed in bivalve nacre. Here we present the first direct observation of ACC precursors to nacre formation, obtained from the growth front of nacre in gastropodmore » shells from red abalone (Haliotis rufescens), using synchrotron spectromicroscopy. Surprisingly, the abalone nacre data show the same ACC phases that are precursors to calcite (CaCO 3) formation in sea urchin spicules, and not proto-aragonite or poorly crystalline aragonite (pAra), as expected for aragonitic nacre. In contrast, we find pAra in coral.« less

Reef fishes have higher parasite richness at unfished Palmyra Atoll compared to fished Kiritimati Island

USGS Publications Warehouse

Lafferty, Kevin D.; Shaw, Jenny C.; Kuris, Armand M.

2008-01-01

We compared parasite communities at two coral atolls in the Line Islands chain of the central Pacific (Kiritimati Island and Palmyra Atoll). Palmyra Atoll is relatively pristine while Kiritimati Island is heavily fished. At each island, we sampled five fish species for helminth and arthropod endoparasites: Chromis margaritifer, Plectroglyphidodon dickii,Paracirrhites arcatus, Acanthurus nigricans, and Lutjanus bohar. The surveys found monogeneans, digeneans, cestodes, nematodes, acanthocephalans, and copepods. Parasite richness was higher at Palmyra compared to Kiritimati for all five fish species. Fishes from Palmyra also tended to have more parasites species per host, higher parasite prevalence, and higher parasite abundance than did fishes from Kiritimati. The lower parasitism at Kiritimati may result from a simplified food web due to over fishing. Low biodiversity could impair parasite transmission by reducing the availability of hosts required by parasites with complex life cycles. Most notably, the lower abundances of larval shark tapeworms at Kiritimati presumably reflect the fact that fishing has greatly depleted sharks there in comparison to Palmyra.

The Resilience of Coral Reefs Across a Hierarchy of Spatial and Temporal scales

NASA Astrophysics Data System (ADS)

Mumby, P. J.

2016-02-01

Resilience is a dynamical property of ecosystems that integrates processes of recovery, disturbance and internal dynamics, including reinforcing feedbacks. As such, resilience is a useful framework to consider how ecosystems respond to multiple drivers occurring over multiple scales. Many insights have emerged recently including the way in which stressors can combine synergistically to deplete resilience. However, while recent advances have mapped resilience across seascapes, most studies have not captured emergent spatial dependencies and dynamics across the seascape (e.g., independent box models are run across the seascape in isolation). Here, we explore the dynamics that emerge when the seascape is `wired up' using data on larval dispersal, thereby giving a fully spatially-realistic model. We then consider how dynamics change across even larger, biogeographic scales, posing the question, `are there robust and global "rules of thumb" for the resilience of a single ecosystem?'. Answers to this question will help managers tailor their interventions and research needs for their own jurisdiction.

Genetic blueprint of the zoonotic pathogen Toxocara canis

PubMed Central

Zhu, Xing-Quan; Korhonen, Pasi K.; Cai, Huimin; Young, Neil D.; Nejsum, Peter; von Samson-Himmelstjerna, Georg; Boag, Peter R.; Tan, Patrick; Li, Qiye; Min, Jiumeng; Yang, Yulan; Wang, Xiuhua; Fang, Xiaodong; Hall, Ross S.; Hofmann, Andreas; Sternberg, Paul W.; Jex, Aaron R.; Gasser, Robin B.

2015-01-01

Toxocara canis is a zoonotic parasite of major socioeconomic importance worldwide. In humans, this nematode causes disease (toxocariasis) mainly in the under-privileged communities in developed and developing countries. Although relatively well studied from clinical and epidemiological perspectives, to date, there has been no global investigation of the molecular biology of this parasite. Here we use next-generation sequencing to produce a draft genome and transcriptome of T. canis to support future biological and biotechnological investigations. This genome is 317 Mb in size, has a repeat content of 13.5% and encodes at least 18,596 protein-coding genes. We study transcription in a larval, as well as adult female and male stages, characterize the parasite’s gene-silencing machinery, explore molecules involved in development or host–parasite interactions and predict intervention targets. The draft genome of T. canis should provide a useful resource for future molecular studies of this and other, related parasites. PMID:25649139

Relevant principal factors affecting the reproducibility of insect primary culture.

PubMed

Ogata, Norichika; Iwabuchi, Kikuo

2017-06-01

The primary culture of insect cells often suffers from problems with poor reproducibility in the quality of the final cell preparations. The cellular composition of the explants (cell number and cell types), surgical methods (surgical duration and surgical isolation), and physiological and genetic differences between donors may be critical factors affecting the reproducibility of culture. However, little is known about where biological variation (interindividual differences between donors) ends and technical variation (variance in replication of culture conditions) begins. In this study, we cultured larval fat bodies from the Japanese rhinoceros beetle, Allomyrina dichotoma, and evaluated, using linear mixed models, the effect of interindividual variation between donors on the reproducibility of the culture. We also performed transcriptome analysis of the hemocyte-like cells mainly seen in the cultures using RNA sequencing and ultrastructural analyses of hemocytes using a transmission electron microscope, revealing that the cultured cells have many characteristics of insect hemocytes.

Phylogenetic analysis of genes involved in mycosporine-like amino acid biosynthesis in symbiotic dinoflagellates.

PubMed

Rosic, Nedeljka N

2012-04-01

Mycosporine-like amino acids (MAAs) are multifunctional secondary metabolites involved in photoprotection in many marine organisms. As well as having broad ultraviolet (UV) absorption spectra (310-362 nm), these biological sunscreens are also involved in the prevention of oxidative stress. More than 20 different MAAs have been discovered so far, characterized by distinctive chemical structures and a broad ecological distribution. Additionally, UV-screening MAA metabolites have been investigated and used in biotechnology and cosmetics. The biosynthesis of MAAs has been suggested to occur via either the shikimate or pentose phosphate pathways. Despite their wide distribution in marine and freshwater species and also the commercial application in cosmetic products, there are still a number of uncertainties regarding the genetic, biochemical, and evolutionary origin of MAAs. Here, using a transcriptome-mining approach, we identify the gene counterparts from the shikimate or pentose phosphate pathway involved in MAA biosynthesis within the sequences of the reef-building coral symbiotic dinoflagellates (genus Symbiodinium). We also report the highly similar sequences of genes from the proposed MAA biosynthetic pathway involved in the metabolism of 4-deoxygadusol (direct MAA precursor) in various Symbiodinium strains confirming their algal origin and conserved nature. Finally, we reveal the separate identity of two O-methyltransferase genes, possibly involved in MAA biosynthesis, as well as nonribosomal peptide synthetase and adenosine triphosphate grasp homologs in symbiotic dinoflagellates. This study provides a biochemical and phylogenetic overview of the genes from the proposed MAA biosynthetic pathway with a focus on coral endosymbionts.

Transcript expression plasticity as a response to alternative larval host plants in the speciation process of corn and rice strains of Spodoptera frugiperda.

PubMed

Silva-Brandão, Karina Lucas; Horikoshi, Renato Jun; Bernardi, Daniel; Omoto, Celso; Figueira, Antonio; Brandão, Marcelo Mendes

2017-10-16

Our main purpose was to evaluate the expression of plastic and evolved genes involved in ecological speciation in the noctuid moth Spodoptera frugiperda, the fall armyworm (FAW); and to demonstrate how host plants might influence lineage differentiation in this polyphagous insect. FAW is an important pest of several crops worldwide, and it is differentiated into host plant-related strains, corn (CS) and rice strains (RS). RNA-Seq and transcriptome characterization were applied to evaluate unbiased genetic expression differences in larvae from the two strains, fed on primary (corn) and alternative (rice) host plants. We consider that genes that are differently regulated by the same FAW strain, as a response to different hosts, are "plastic". Otherwise, differences in gene expression between the two strains fed on the same host are considered constitutive differences. Individual performance parameters (larval and pupal weight) varied among conditions (strains vs. hosts). A total of 3657 contigs was related to plastic response, and 2395 contigs were differentially regulated in the two strains feeding on preferential and alternative hosts (constitutive contigs). Three molecular functions were present in all comparisons, both down- and up-regulated: oxidoreductase activity, metal-ion binding, and hydrolase activity. Metabolization of foreign chemicals is among the key functions involved in the phenotypic variation of FAW strains. From an agricultural perspective, high plasticity in families of detoxifying genes indicates the capacity for a rapid response to control compounds such as insecticides.

CONTRIBUTIONS OF SEXUAL AND ASEXUAL REPRODUCTION TO POPULATION STRUCTURE IN THE CLONAL SOFT CORAL, ALCYONIUM RUDYI.

PubMed

McFadden, Catherine S

1997-02-01

Numerous studies of population structure in sessile clonal marine invertebrates have demonstrated low genotypic diversity and nonequilibrium genotype frequencies within local populations that are monopolized by relatively few, highly replicated genets. All of the species studied to date produce planktonic sexual propagules capable of dispersing long distances; despite local genotypic disequilibria, populations are often panmictic over large geographic areas. The population structure paradigm these species represent may not be typical of the majority of clonal invertebrate groups, however, which are believed to produce highly philopatric sexual propagules. I used allozyme variation to examine the population structure of the temperate soft coral, Alcyonium rudyi, a typical clonal species whose sexually produced larvae and asexually produced ramets both have very low dispersal capabilities. Like other clonal plants and invertebrates, the local population dynamics of A. rudyi are dominated by asexual reproduction, and recruitment of new sexually produced genets occurs infrequently. As expected from its philopatric larval stage, estimates of genetic differentiation among populations of A. rudyi were highly significant at all spatial scales examined (mean θ = 0.300 among 20 populations spanning a 1100-km range), suggesting that genetic exchange seldom occurs among populations separated by as little as a few hundred meters. Mapping of multilocus allozyme genotypes within a dense aggregation of A. rudyi ramets confirmed that dispersal of asexual propagules is also very limited: members of the same genet usually remain within < 50 cm of one another on the same rock surface. Unlike most previously studied clonal invertebrates, populations of A. rudyi do not appear to be dominated by a few widespread genets: estimates of genotypic diversity (G o ) within 20 geographically distinct populations did not differ from expectations for outcrossing, sexual populations. Despite theoretical suggestions that philopatric dispersal combined with typically small effective population sizes should promote inbreeding in clonal species, inbreeding does not appear to contribute significantly to the population structure of A. rudyi. Genet genotype frequencies conformed to Hardy-Weinberg expectations in all populations, and inbreeding coefficients (f) were close to zero. In general, the population structure of A. rudyi did not differ significantly from that observed among outcrossing sexual species with philopatric larval dispersal. Age estimates suggest, however, that genets of A. rudyi live for many decades. Genet longevity may promote high genotypic diversity within A. rudyi populations and may be the most important evolutionary consequence of clonal reproduction in this species and the many others that share its dispersal characteristics. © 1997 The Society for the Study of Evolution.

Transcriptome Analysis and Discovery of Genes Relevant to Development in Bradysia odoriphaga at Three Developmental Stages.

PubMed

Gao, Huanhuan; Zhai, Yifan; Wang, Wenbo; Chen, Hao; Zhou, Xianhong; Zhuang, Qianying; Yu, Yi; Li, Rumei

2016-01-01

Bradysia odoriphaga (Diptera: Sciaridae) is the most important pest of Chinese chive (Allium tuberosum) in Asia; however, the molecular genetics are poorly understood. To explore the molecular biological mechanism of development, Illumina sequencing and de novo assembly were performed in the third-instar, fourth-instar, and pupal B. odoriphaga. The study resulted in 16.2 Gb of clean data and 47,578 unigenes (≥125 bp) contained in 7,632,430 contigs, 46.21% of which were annotated from non-redundant protein (NR), Gene Ontology (GO), Clusters of Orthologous Groups (COG), Eukaryotic Orthologous Groups (KOG), and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. It was found that 19.67% of unigenes matched the homologous species mainly, including Aedes aegypti, Culex quinquefasciatus, Ceratitis capitata, and Anopheles gambiae. According to differentially expressed gene (DEG) analysis, 143, 490, and 309 DEGs were annotated as involved in the developmental process in the GO database respectively, in the comparisons of third-instar and fourth-instar larvae, third-instar larvae and pupae, and fourth-instar larvae and pupae. Twenty-five genes were closely related to these processes, including developmental process, reproduction process, and reproductive organs development and programmed cell death (PCD). The information of unigenes assembled in B. odoriphaga through transcriptome and DEG analyses could provide a detailed genetic basis and regulated information for elaborating the developmental mechanism from the larval, pre-pupal to pupal stages of B. odoriphaga.

RNA-sequencing analysis reveals abundant developmental stage-specific and immunity-related genes in the pollen beetle Meligethes aeneus.

PubMed

Vogel, H; Badapanda, C; Knorr, E; Vilcinskas, A

2014-02-01

The pollen beetle (Meligethes aeneus) is a major pest of oilseed rape (Brassica napus) and other cruciferous crops in Europe. Pesticide-resistant pollen beetle populations are emerging, increasing the economic impact of this species. We isolated total RNA from the larval and adult stages, the latter either naïve or immunized by injection with bacteria and yeast. High-throughput RNA sequencing (RNA-Seq) was carried out to establish a comprehensive transcriptome catalogue and to screen for developmental stage-specific and immunity-related transcripts. We assembled the transcriptome de novo by combining sequence tags from all developmental stages and treatments. Gene expression data based on normalized read counts revealed several functional gene categories that were differentially expressed between larvae and adults, particularly genes associated with digestion and detoxification that were induced in larvae, and genes associated with reproduction and environmental signalling that were induced in adults. We also identified many genes associated with microbe recognition, immunity-related signalling and defence effectors, such as antimicrobial peptides (AMPs) and lysozymes. Digital gene expression analysis revealed significant differences in the profile of AMPs expressed in larvae, naïve adults and immune-challenged adults, providing insight into the steady-state differences between developmental stages and the complex transcriptional remodelling that occurs following the induction of immunity. Our data provide insight into the adaptive mechanisms used by phytophagous insects and could lead to the development of more effective control strategies for insect pests. © 2013 The Royal Entomological Society.

A genome-wide survey of maternal and embryonic transcripts during Xenopus tropicalis development.

PubMed

Paranjpe, Sarita S; Jacobi, Ulrike G; van Heeringen, Simon J; Veenstra, Gert Jan C

2013-11-06

Dynamics of polyadenylation vs. deadenylation determine the fate of several developmentally regulated genes. Decay of a subset of maternal mRNAs and new transcription define the maternal-to-zygotic transition, but the full complement of polyadenylated and deadenylated coding and non-coding transcripts has not yet been assessed in Xenopus embryos. To analyze the dynamics and diversity of coding and non-coding transcripts during development, both polyadenylated mRNA and ribosomal RNA-depleted total RNA were harvested across six developmental stages and subjected to high throughput sequencing. The maternally loaded transcriptome is highly diverse and consists of both polyadenylated and deadenylated transcripts. Many maternal genes show peak expression in the oocyte and include genes which are known to be the key regulators of events like oocyte maturation and fertilization. Of all the transcripts that increase in abundance between early blastula and larval stages, about 30% of the embryonic genes are induced by fourfold or more by the late blastula stage and another 35% by late gastrulation. Using a gene model validation and discovery pipeline, we identified novel transcripts and putative long non-coding RNAs (lncRNA). These lncRNA transcripts were stringently selected as spliced transcripts generated from independent promoters, with limited coding potential and a codon bias characteristic of noncoding sequences. Many lncRNAs are conserved and expressed in a developmental stage-specific fashion. These data reveal dynamics of transcriptome polyadenylation and abundance and provides a high-confidence catalogue of novel and long non-coding RNAs.

The Transcriptome of the Zoanthid Protopalythoa variabilis (Cnidaria, Anthozoa) Predicts a Basal Repertoire of Toxin-like and Venom-Auxiliary Polypeptides.

PubMed

Huang, Chen; Morlighem, Jean-Étienne Rl; Zhou, Hefeng; Lima, Érica P; Gomes, Paula B; Cai, Jing; Lou, Inchio; Pérez, Carlos D; Lee, Simon Ming; Rádis-Baptista, Gandhi

2016-10-05

Protopalythoa is a zoanthid that, together with thousands of predominantly marine species, such as hydra, jellyfish, and sea anemones, composes the oldest eumetazoan phylum, i.e., the Cnidaria. Some of these species, such as sea wasps and sea anemones, are highly venomous organisms that can produce deadly toxins for preying, for defense or for territorial disputes. Despite the fact that hundreds of organic and polypeptide toxins have been characterized from sea anemones and jellyfish, practically nothing is known about the toxin repertoire in zoanthids. Here, based on a transcriptome analysis of the zoanthid Protopalythoa variabilis, numerous predicted polypeptides with canonical venom protein features are identified. These polypeptides comprise putative proteins from different toxin families: neurotoxic peptides, hemostatic and hemorrhagic toxins, membrane-active (pore-forming) proteins, protease inhibitors, mixed-function venom enzymes, and venom auxiliary proteins. The synthesis and functional analysis of two of these predicted toxin products, one related to the ShK/Aurelin family and the other to a recently discovered anthozoan toxin, displayed potent in vivo neurotoxicity that impaired swimming in larval zebrafish. Altogether, the complex array of venom-related transcripts that are identified in P. variabilis, some of which are first reported in Cnidaria, provides novel insight into the toxin distribution among species and might contribute to the understanding of composition and evolution of venom polypeptides in toxiferous animals. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Polyphenism in social insects: insights from a transcriptome-wide analysis of gene expression in the life stages of the key pollinator, Bombus terrestris

PubMed Central

2011-01-01

Background Understanding polyphenism, the ability of a single genome to express multiple morphologically and behaviourally distinct phenotypes, is an important goal for evolutionary and developmental biology. Polyphenism has been key to the evolution of the Hymenoptera, and particularly the social Hymenoptera where the genome of a single species regulates distinct larval stages, sexual dimorphism and physical castes within the female sex. Transcriptomic analyses of social Hymenoptera will therefore provide unique insights into how changes in gene expression underlie such complexity. Here we describe gene expression in individual specimens of the pre-adult stages, sexes and castes of the key pollinator, the buff-tailed bumblebee Bombus terrestris. Results cDNA was prepared from mRNA from five life cycle stages (one larva, one pupa, one male, one gyne and two workers) and a total of 1,610,742 expressed sequence tags (ESTs) were generated using Roche 454 technology, substantially increasing the sequence data available for this important species. Overlapping ESTs were assembled into 36,354 B. terrestris putative transcripts, and functionally annotated. A preliminary assessment of differences in gene expression across non-replicated specimens from the pre-adult stages, castes and sexes was performed using R-STAT analysis. Individual samples from the life cycle stages of the bumblebee differed in the expression of a wide array of genes, including genes involved in amino acid storage, metabolism, immunity and olfaction. Conclusions Detailed analyses of immune and olfaction gene expression across phenotypes demonstrated how transcriptomic analyses can inform our understanding of processes central to the biology of B. terrestris and the social Hymenoptera in general. For example, examination of immunity-related genes identified high conservation of important immunity pathway components across individual specimens from the life cycle stages while olfactory-related genes exhibited differential expression with a wider repertoire of gene expression within adults, especially sexuals, in comparison to immature stages. As there is an absence of replication across the samples, the results of this study are preliminary but provide a number of candidate genes which may be related to distinct phenotypic stage expression. This comprehensive transcriptome catalogue will provide an important gene discovery resource for directed programmes in ecology, evolution and conservation of a key pollinator. PMID:22185240

Transcriptome and Metabolome Analyses of Glucosinolates in Two Broccoli Cultivars Following Jasmonate Treatment for the Induction of Glucosinolate Defense to Trichoplusia ni (Hübner).

PubMed

Ku, Kang-Mo; Becker, Talon M; Juvik, John A

2016-07-15

Lepidopteran larvae growth is influenced by host plant glucosinolate (GS) concentrations, which are, in turn, influenced by the phytohormone jasmonate (JA). In order to elucidate insect resistance biomarkers to lepidopteran pests, transcriptome and metabolome analyses following JA treatments were conducted with two broccoli cultivars, Green Magic and VI-158, which have differentially induced indole GSs, neoglucobrassicin and glucobrassicin, respectively. To test these two inducible GSs on growth of cabbage looper (Trichoplusia ni), eight neonate cabbage looper larvae were placed onto each of three plants per JA treatments (0, 100, 200, 400 µM) three days after treatment. After five days of feeding, weight of larvae and their survival rate was found to decrease with increasing JA concentrations in both broccoli cultivars. JA-inducible GSs were measured by high performance liquid chromatography. Neoglucobrassicin in Green Magic and glucobrassicin in VI-158 leaves were increased in a dose-dependent manner. One or both of these glucosinolates and/or their hydrolysis products showed significant inverse correlations with larval weight and survival (five days after treatment) while being positively correlated with the number of days to pupation. This implies that these two JA-inducible glucosinolates can influence the growth and survival of cabbage looper larvae. Transcriptome profiling supported the observed changes in glucosinolate and their hydrolysis product concentrations following JA treatments. Several genes related to GS metabolism differentiate the two broccoli cultivars in their pattern of transcriptional response to JA treatments. Indicative of the corresponding change in indole GS concentrations, transcripts of the transcription factor MYB122, core structure biosynthesis genes (CYP79B2, UGT74B1, SUR1, SOT16, SOT17, and SOT18), an indole glucosinolate side chain modification gene (IGMT1), and several glucosinolate hydrolysis genes (TGG1, TGG2, and ESM1) were significantly increased in Green Magic (statistically significant in most cases at 400 µM) while UGT74B1 and MYB122 were significantly increased in VI-158. Therefore, these metabolite and transcript biomarker results indicate that transcriptome profiling can identify genes associated with the formation of two different indole GS and their hydrolysis products. Therefore, these metabolite and transcript biomarkers could be useful in an effective marker-assisted breeding strategy for resistance to generalist lepidopteran pests in broccoli and potentially other Brassica vegetables.

Transcriptome and Metabolome Analyses of Glucosinolates in Two Broccoli Cultivars Following Jasmonate Treatment for the Induction of Glucosinolate Defense to Trichoplusia ni (Hübner)

PubMed Central

Ku, Kang-Mo; Becker, Talon M.; Juvik, John A.

2016-01-01

Lepidopteran larvae growth is influenced by host plant glucosinolate (GS) concentrations, which are, in turn, influenced by the phytohormone jasmonate (JA). In order to elucidate insect resistance biomarkers to lepidopteran pests, transcriptome and metabolome analyses following JA treatments were conducted with two broccoli cultivars, Green Magic and VI-158, which have differentially induced indole GSs, neoglucobrassicin and glucobrassicin, respectively. To test these two inducible GSs on growth of cabbage looper (Trichoplusia ni), eight neonate cabbage looper larvae were placed onto each of three plants per JA treatments (0, 100, 200, 400 µM) three days after treatment. After five days of feeding, weight of larvae and their survival rate was found to decrease with increasing JA concentrations in both broccoli cultivars. JA-inducible GSs were measured by high performance liquid chromatography. Neoglucobrassicin in Green Magic and glucobrassicin in VI-158 leaves were increased in a dose-dependent manner. One or both of these glucosinolates and/or their hydrolysis products showed significant inverse correlations with larval weight and survival (five days after treatment) while being positively correlated with the number of days to pupation. This implies that these two JA-inducible glucosinolates can influence the growth and survival of cabbage looper larvae. Transcriptome profiling supported the observed changes in glucosinolate and their hydrolysis product concentrations following JA treatments. Several genes related to GS metabolism differentiate the two broccoli cultivars in their pattern of transcriptional response to JA treatments. Indicative of the corresponding change in indole GS concentrations, transcripts of the transcription factor MYB122, core structure biosynthesis genes (CYP79B2, UGT74B1, SUR1, SOT16, SOT17, and SOT18), an indole glucosinolate side chain modification gene (IGMT1), and several glucosinolate hydrolysis genes (TGG1, TGG2, and ESM1) were significantly increased in Green Magic (statistically significant in most cases at 400 µM) while UGT74B1 and MYB122 were significantly increased in VI-158. Therefore, these metabolite and transcript biomarker results indicate that transcriptome profiling can identify genes associated with the formation of two different indole GS and their hydrolysis products. Therefore, these metabolite and transcript biomarkers could be useful in an effective marker-assisted breeding strategy for resistance to generalist lepidopteran pests in broccoli and potentially other Brassica vegetables. PMID:27428958

History of Indo-Pacific coral reef systems since the last glaciation: Development patterns and controlling factors

NASA Astrophysics Data System (ADS)

Montaggioni, Lucien F.

2005-06-01

A significant body of new information about the development of coral reefs during the last 23 ka has been generated in the last three decades. In the Indo-Pacific province, structures from a variety of geodynamic settings have been investigated using subsurface drilling and submersible diving. This paper is based principally on the re-examination of the core dataset from the literature, with reconversion of many previously published radiocarbon ages into calendar dates. Seven framework and three detrital facies were identified on the basis of the nature and growth shapes of dominant framework builders, and on that of the texture of sediments, respectively. Framework facies in high-hydrodynamic energy settings were dominated by an association of coralline algae and robust-branching corals ( Acropora robusta group, A. gr. humilis, A. palifera, Pocillopora damicornis) with locally encrusting coral forms (faviids). In moderate energy environments, these were replaced by domal ( Porites), tabular-branching ( Acropora gr. hyacinthus) and arborescent ( Acropora gr. muricata), whereas sheltered areas included an association of arborescent, foliaceous ( Montipora, Pavona) and encrusting coral species. Detrital facies comprise coral rubble, carbonate sand and mud. On compositional and textural bases, four main sand subfacies were recognized: coralgal rudstone to packstone; coral-molluscan grainstone/packstone; molluscan-foraminiferal grainstone/packstone; and green algal ( Halimeda) grainstone/packstone. Despite some overlaps in the sand facies association, each subfacies can provide additional support to reconstruction of paleoreef environments. Three types of framework facies association were identified within entire reef-margin sequences: framework of homogeneous composition reflecting stability of environmental conditions through time; superimposition of two distinct frameworks, usually as deeper water corals overlain by shallower, higher energy ones, and recurrent alternations of shallower and deeper coral assemblages. The two last associations resulted probably from lateral displacements of coral communities in response to rapid changes in accommodation space. Such facies transitions also are described from backreef sediment piles: gravel graded into sand and mud successively as a result of upward shallowing. The degree of reef development seems to be linked to coral community structure. Communities consisting principally of branching and domal coral forms favoured substantial accretion and the formation of well-developed reefs, whereas assemblages comprising foliaceous and encrusting colonies produced only incipient reefs. Within reef systems, the proportions of detritus over framework tend to increase as hydrodynamic energy declines. The Indo-Pacific reef systems are classified into four anatomy types on the basis of dominant depositional patterns: balanced aggrading/onlapping, unbalanced aggrading/downlapping, prograding and backstepping types. Vertical accretion rates of frameworks are highly variable and are not directly dictated by coral growth habits. However, the highest rates recorded (up to 20 mm year -1) relate to tabular- and arborescent-acroporid rich sections. Abrupt variations in the aggradation rates of framework are recorded in sequences at the transitional zone between two distinct coral assemblages. In detritus-dominated sequences, accumulation rates range from 0.2 to about 40 mm year -1, with higher values suggesting intense hurricane-controlled deposition. In addition, accretion rates also seem to depend on water-energy conditions. In high-energy environments, aggradation rates did not exceed 12 mm year -1, but reached 25 mm year -1 in more protected areas. By contrast, lateral accretion operated at an average rate of 90 mm year -1 in agitated waters, while it did not exceed the mean rate of 55 mm year -1 in calm waters. Changes in accretion rates appear to be linked to reef growth modes. In the reef zones driven by a "keep-up" mode, mean vertical accretion rates range at around 6 mm year -1. The reef zones developed through a "catch-up" mode at rates of 3-4 mm year -1. There was little variation in accretion rates according to latitude. At the Last Glacial Maximum, from 23 to about 19 ka BP, reefs (Reef Generation RGO) only developed along what were to become the foreslopes of present reefs, forming accumulations a few metres thick at vertical rates of up to 1 mm year -1. The rapid postglacial rise in sea level, from about 19 to 6.5 ka BP, was accompanied by the settlement of three successive reef generations (the so called RGI, RGII and RGIII), within the periods 17.5-14.7, 13.8-11.5 and 10 ka BP to the Present. During the Postglacial transgression, regional to local differences in gross morphology and internal architecture of the reefs have been determined by differing sea-level histories in combination with neotectonics and typographic factors. Locally, reef colonization seems to have been facilitated or prevented chiefly by small-scale topographic features. Development during subsequent deglaciation was probably largely independent of variations in sea surface temperatures. Water turbidity also seems to have been only a minor determinant of reef settlement and growth, but may locally have controlled the composition of coral communities, resulting in the growth of turbidity-tolerant domal and foliaceous forms. Changes in atmospheric CO 2 levels remained within the tolerance thresholds for reef calcification. The three main reef growth episodes coincide roughly with rapid increases in atmospheric pCO 2. Dust input and variations in sea surface salinities seem to have had a very limited control on reef growth. The LGM was characterized by salinities comparable with those of the present, but by higher dust fluxes. By contrast, nutrient levels, hydrodynamic energy, and to a lesser, extent coral recruitment in relation to substrate availability and ocean circulation, have played major roles in determining reef accretion patterns at both local and regional scales. Two periods of increased upwelling in the western Indian Ocean, at 15.3 and 11.5-10.8 ka BP, coincided with the demise of RGI and RGII. During deglaciation, high-frequency storm events probably led to a scarcity of typical growth framework reefs and favoured the formation of structures composed of reworked and recemented coral framework. Storm control may have been particularly important in the mid-Holocene when water depths over incipient reefs were greater than 5 m. From the LGM to the early Holocene, coral settlement has probably declined due to a lack of suitable nurseries, until the modern patterns of ocean circulation were established and thus favoured larval dispersal from refuges. It is highly desirable to improve analysis of the core database and to increase the number of core-transects, including forereef sites, to enhance our knowledge of Recent reef development.

Coral transplantation triggers shift in microbiome and promotion of coral disease associated potential pathogens

PubMed Central

Casey, Jordan M.; Connolly, Sean R.; Ainsworth, Tracy D.

2015-01-01

By cultivating turf algae and aggressively defending their territories, territorial damselfishes in the genus Stegastes play a major role in shaping coral-algal dynamics on coral reefs. The epilithic algal matrix (EAM) inside Stegastes’ territories is known to harbor high abundances of potential coral disease pathogens. To determine the impact of territorial grazers on coral microbial assemblages, we established a coral transplant inside and outside of Stegastes’ territories. Over the course of one year, the percent mortality of transplanted corals was monitored and coral samples were collected for microbial analysis. As compared to outside damselfish territories, Stegastes were associated with a higher rate of mortality of transplanted corals. However, 16S rDNA sequencing revealed that territorial grazers do not differentially impact the microbial assemblage of corals exposed to the EAM. Regardless of Stegastes presence or absence, coral transplantation resulted in a shift in the coral-associated microbial community and an increase in coral disease associated potential pathogens. Further, transplanted corals that suffer low to high mortality undergo a microbial transition from a microbiome similar to that of healthy corals to that resembling the EAM. These findings demonstrate that coral transplantation significantly impacts coral microbial communities, and transplantation may increase susceptibility to coral disease. PMID:26144865

Biosynthesis of coral settlement cue tetrabromopyrrole in marine bacteria by a uniquely adapted brominase–thioesterase enzyme pair

PubMed Central

El Gamal, Abrahim; Agarwal, Vinayak; Diethelm, Stefan; Rahman, Imran; Schorn, Michelle A.; Sneed, Jennifer M.; Louie, Gordon V.; Whalen, Kristen E.; Mincer, Tracy J.; Noel, Joseph P.; Paul, Valerie J.; Moore, Bradley S.

2016-01-01

Halogenated pyrroles (halopyrroles) are common chemical moieties found in bioactive bacterial natural products. The halopyrrole moieties of mono- and dihalopyrrole-containing compounds arise from a conserved mechanism in which a proline-derived pyrrolyl group bound to a carrier protein is first halogenated and then elaborated by peptidic or polyketide extensions. This paradigm is broken during the marine pseudoalteromonad bacterial biosynthesis of the coral larval settlement cue tetrabromopyrrole (1), which arises from the substitution of the proline-derived carboxylate by a bromine atom. To understand the molecular basis for decarboxylative bromination in the biosynthesis of 1, we sequenced two Pseudoalteromonas genomes and identified a conserved four-gene locus encoding the enzymes involved in its complete biosynthesis. Through total in vitro reconstitution of the biosynthesis of 1 using purified enzymes and biochemical interrogation of individual biochemical steps, we show that all four bromine atoms in 1 are installed by the action of a single flavin-dependent halogenase: Bmp2. Tetrabromination of the pyrrole induces a thioesterase-mediated offloading reaction from the carrier protein and activates the biosynthetic intermediate for decarboxylation. Insights into the tetrabrominating activity of Bmp2 were obtained from the high-resolution crystal structure of the halogenase contrasted against structurally homologous halogenase Mpy16 that forms only a dihalogenated pyrrole in marinopyrrole biosynthesis. Structure-guided mutagenesis of the proposed substrate-binding pocket of Bmp2 led to a reduction in the degree of halogenation catalyzed. Our study provides a biogenetic basis for the biosynthesis of 1 and sets a firm foundation for querying the biosynthetic potential for the production of 1 in marine (meta)genomes. PMID:27001835

Mortalities of Eastern and Pacific oyster Larvae caused by the pathogens Vibrio coralliilyticus and Vibrio tubiashii.

PubMed

Richards, Gary P; Watson, Michael A; Needleman, David S; Church, Karlee M; Häse, Claudia C

2015-01-01

Vibrio tubiashii is reported to be a bacterial pathogen of larval Eastern oysters (Crassostrea virginica) and Pacific oysters (Crassostrea gigas) and has been associated with major hatchery crashes, causing shortages in seed oysters for commercial shellfish producers. Another bacterium, Vibrio coralliilyticus, a well-known coral pathogen, has recently been shown to elicit mortality in fish and shellfish. Several strains of V. coralliilyticus, such as ATCC 19105 and Pacific isolates RE22 and RE98, were misidentified as V. tubiashii until recently. We compared the mortalities caused by two V. tubiashii and four V. coralliilyticus strains in Eastern and Pacific oyster larvae. The 50% lethal dose (LD50) of V. coralliilyticus in Eastern oysters (defined here as the dose required to kill 50% of the population in 6 days) ranged from 1.1 × 10(4) to 3.0 × 10(4) CFU/ml seawater; strains RE98 and RE22 were the most virulent. This study shows that V. coralliilyticus causes mortality in Eastern oyster larvae. Results for Pacific oysters were similar, with LD50s between 1.2 × 10(4) and 4.0 × 10(4) CFU/ml. Vibrio tubiashii ATCC 19106 and ATCC 19109 were highly infectious toward Eastern oyster larvae but were essentially nonpathogenic toward healthy Pacific oyster larvae at dosages of ≥1.1 × 10(4) CFU/ml. These data, coupled with the fact that several isolates originally thought to be V. tubiashii are actually V. coralliilyticus, suggest that V. coralliilyticus has been a more significant pathogen for larval bivalve shellfish than V. tubiashii, particularly on the U.S. West Coast, contributing to substantial hatchery-associated morbidity and mortality in recent years. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Contrasting reproductive strategies in three deep-sea octocorals from eastern Canada: Primnoa resedaeformis, Keratoisis ornata, and Anthomastus grandiflorus

NASA Astrophysics Data System (ADS)

Mercier, A.; Hamel, J.-F.

2011-06-01

Various aspects of reproduction were studied in three deep-sea octocorals belonging to the order Alcyonacea that co-occur at bathyal depths on the continental edge and the slope of eastern Canada. The main goals were to expand knowledge of deep-water heterotrophic corals and ascertain whether reproductive strategies could explain the known patterns of occurrence. Anthomastus grandiflorus is a gonochoric species with a female-biased sex ratio that exhibits internal fertilization and brooding of planula larvae. Conversely, Primnoa resedaeformis and Keratoisis ornata rely on broadcast spawning and external fertilization; their sexuality remains undetermined as spermatocysts were not found. In P. resedaeformis, the presence of mixed size classes of oocytes in samples from all months, depths, and locations studied suggests continuous oogenesis or overlapping development of oocyte cohorts, indicative of a gametogenic cycle spanning more than a year. No evidence of periodicity was found in this species, although it could have been masked by the striking bathymetric variation in potential relative fecundity (oocytes polyp-1). The two other octocorals displayed a clear annual breeding pattern. Spawning in K. ornata and larval release in A. grandiflorus occurred in late summer and fall, respectively, possibly in response to environmental factors, as supported by shifts in the reproductive peak of A. grandiflorus across latitudes. The three species are presumed to share a nonfeeding larval mode, and data on their reproductive potential do not present any striking disparities. Published data on bycatches and video surveys in Atlantic Canada indicate that the gonochoric brooder A. grandiflorus is more widely distributed than the two free spawners, P. resedaeformis and K. ornata, which is contrary to common dispersal potential paradigms.

Ichthyoplankton assemblages in the Gulf of Nicoya and Golfo Dulce embayments, Pacific coast of Costa Rica.

PubMed

Molina-Ureña, H

1996-12-01

Ichthyoplankton surveys were conducted in December (rainy season), 1993 and February (dry season), 1994, during the RV Victor Hensen German-Costa Rican Expedition to the Gulf of Nicoya and Gulfo Dulce, Costa Rica. Samples from the inner, central, and outer areas of each gulf were collected in oblique tows with a bongo net of 0.6 m mouth diameter, 2.5 m long and 1000-micron mesh. A total of 416 fish larvae of 22 families were sorted out of 14 samples. Stations of both the maximum (11) and the minimum (1) family richness were located in Golfo Dulce. Mean total larval abundances were 124.9 and 197.2 individuals 10 m-2 for the Gulf of Nicoya and Golfo Dulce, respectively, while mean larval densities ranged from 95.3 larvae 10 m-2 in December to 236.7 larvae 10 m-2 in February. However, no statistical differences between gulfs or seasons were detected, due to the high within-group variability. Cluster Analysis, Multi-Dimensional Scaling (MDS), and non-parametric tests showed two well-defined major groups: (1) the Gulf of Nicoya neritic assemblage, represented by Engraulids, Sciaenids, and Gobiids (inner and central stations), and (2) the oceanic assemblage, dominated by Myctophids, Bregmacerotids, Ophiidids, and Trichiurids (outer stations off the Gulf of Nicoya and Golfo Dulce). A third, although less defined group, was an Ophichthid-dominated assemblage (typical in areas nearby coral or rocky reefs). These assemblages closely resemble the clusters based upon adult fish data of the beamtrawl catches of the same cruise. This publication is the first to report on the ichthyoplankton community of Golfo Dulce.

Bacterial community dynamics are linked to patterns of coral heat tolerance

NASA Astrophysics Data System (ADS)

Ziegler, Maren; Seneca, Francois O.; Yum, Lauren K.; Palumbi, Stephen R.; Voolstra, Christian R.

2017-02-01

Ocean warming threatens corals and the coral reef ecosystem. Nevertheless, corals can be adapted to their thermal environment and inherit heat tolerance across generations. In addition, the diverse microbes that associate with corals have the capacity for more rapid change, potentially aiding the adaptation of long-lived corals. Here, we show that the microbiome of reef corals is different across thermally variable habitats and changes over time when corals are reciprocally transplanted. Exposing these corals to thermal bleaching conditions changes the microbiome for heat-sensitive corals, but not for heat-tolerant corals growing in habitats with natural high heat extremes. Importantly, particular bacterial taxa predict the coral host response in a short-term heat stress experiment. Such associations could result from parallel responses of the coral and the microbial community to living at high natural temperatures. A competing hypothesis is that the microbial community and coral heat tolerance are causally linked.

Cryptic effects of habitat declines: coral-associated fishes avoid coral-seaweed interactions due to visual and chemical cues.

PubMed

Brooker, Rohan M; Brandl, Simon J; Dixson, Danielle L

2016-01-04

Seaweed-dominated coral reefs are becoming increasingly common as environmental conditions shift away from those required by corals and toward those ideal for rampant seaweed growth. How coral-associated organisms respond to seaweed will not only impact their fate following environmental change but potentially also the trajectories of the coral communities on which they rely. However, behavioral responses by coral-associated organisms to seaweeds are poorly understood. This study examined interactions between a guild of obligate and opportunistic coral-feeding butterflyfishes (Chaetodontidae) and scleractinian corals to determine whether fishes continue to interact with corals in contact with seaweed or if they are avoided. Under natural conditions, all species interacted almost exclusively with seaweed-free corals. In a controlled patch reef experiment, fishes avoided corals in physical contact with seaweed, irrespective of dietary preferences. When visual seaweed cues were removed, butterflyfish continued to avoid corals that had been in contact with the allelopathic Galaxaura filamentosa, suggesting that chemical cues produced by coral-seaweed interactions are repellent. These findings suggest that, due to deleterious visual and chemical cues produced by coral-seaweed interactions, coral-associated organisms may struggle to locate resources as seaweed-free corals decline in abundance.

Spectral response of the coral rubble, living corals, and dead corals: study case on the Spermonde Archipelago, Indonesia

NASA Astrophysics Data System (ADS)

Nurdin, Nurjannah; Komatsu, Teruhisa; Yamano, Hiroya; Arafat, Gulam; Rani, Chair; Akbar AS, M.

2012-10-01

Coral reefs play important ecological services such as providing foods, biodiversity, nutrient recycling etc. for human society. On the other hand, they are threatened by human impacts such as illegal fishing and environmental changes such as rises of sea water temperature and sea level due to global warming. Thus, it is very important to monitor dynamic spatial distributions of coral reefs and related habitats such as coral rubble, dead coral, bleached corals, seagrass, etc. Hyperspectral data, in particular, offer high potential for characterizing and mapping coral reefs because of their capability to identify individual reef components based on their detailed spectral response. We studied the optical properties by measuring in situ spectra of living corals, dead coral and coral rubble covered with algae. Study site was selected in Spermonde archipelago, South Sulawesi, Indonesia because this area is included in the highest diversity of corals in the world named as Coral Triangle, which is recognized as the global centre of marine biodiversity and a global priority for conservation. Correlation analysis and cluster analysis support that there are distinct differences in reflectance spectra among categories. Common spectral characteristic of living corals, dead corals and coral rubble covered with algae was a reflectance minimum at 674 nm. Healthy corals, dead coral covered with algae and coral rubble covered with algae showed high similarity of spectral reflectance. It is estimated that this is due to photsynthetic pigments.

Macroalgae Decrease Growth and Alter Microbial Community Structure of the Reef-Building Coral, Porites astreoides

PubMed Central

Vega Thurber, Rebecca; Burkepile, Deron E.; Correa, Adrienne M. S.; Thurber, Andrew R.; Shantz, Andrew A.; Welsh, Rory; Pritchard, Catharine; Rosales, Stephanie

2012-01-01

With the continued and unprecedented decline of coral reefs worldwide, evaluating the factors that contribute to coral demise is of critical importance. As coral cover declines, macroalgae are becoming more common on tropical reefs. Interactions between these macroalgae and corals may alter the coral microbiome, which is thought to play an important role in colony health and survival. Together, such changes in benthic macroalgae and in the coral microbiome may result in a feedback mechanism that contributes to additional coral cover loss. To determine if macroalgae alter the coral microbiome, we conducted a field-based experiment in which the coral Porites astreoides was placed in competition with five species of macroalgae. Macroalgal contact increased variance in the coral-associated microbial community, and two algal species significantly altered microbial community composition. All macroalgae caused the disappearance of a γ-proteobacterium previously hypothesized to be an important mutualist of P. astreoides. Macroalgal contact also triggered: 1) increases or 2) decreases in microbial taxa already present in corals, 3) establishment of new taxa to the coral microbiome, and 4) vectoring and growth of microbial taxa from the macroalgae to the coral. Furthermore, macroalgal competition decreased coral growth rates by an average of 36.8%. Overall, this study found that competition between corals and certain species of macroalgae leads to an altered coral microbiome, providing a potential mechanism by which macroalgae-coral interactions reduce coral health and lead to coral loss on impacted reefs. PMID:22957055

Macroalgae decrease growth and alter microbial community structure of the reef-building coral, Porites astreoides.

PubMed

Vega Thurber, Rebecca; Burkepile, Deron E; Correa, Adrienne M S; Thurber, Andrew R; Shantz, Andrew A; Welsh, Rory; Pritchard, Catharine; Rosales, Stephanie

2012-01-01

With the continued and unprecedented decline of coral reefs worldwide, evaluating the factors that contribute to coral demise is of critical importance. As coral cover declines, macroalgae are becoming more common on tropical reefs. Interactions between these macroalgae and corals may alter the coral microbiome, which is thought to play an important role in colony health and survival. Together, such changes in benthic macroalgae and in the coral microbiome may result in a feedback mechanism that contributes to additional coral cover loss. To determine if macroalgae alter the coral microbiome, we conducted a field-based experiment in which the coral Porites astreoides was placed in competition with five species of macroalgae. Macroalgal contact increased variance in the coral-associated microbial community, and two algal species significantly altered microbial community composition. All macroalgae caused the disappearance of a γ-proteobacterium previously hypothesized to be an important mutualist of P. astreoides. Macroalgal contact also triggered: 1) increases or 2) decreases in microbial taxa already present in corals, 3) establishment of new taxa to the coral microbiome, and 4) vectoring and growth of microbial taxa from the macroalgae to the coral. Furthermore, macroalgal competition decreased coral growth rates by an average of 36.8%. Overall, this study found that competition between corals and certain species of macroalgae leads to an altered coral microbiome, providing a potential mechanism by which macroalgae-coral interactions reduce coral health and lead to coral loss on impacted reefs.

Big Data Approaches To Coral-Microbe Symbiosis

NASA Astrophysics Data System (ADS)

Zaneveld, J.; Pollock, F. J.; McMinds, R.; Smith, S.; Payet, J.; Hanna, B.; Welsh, R.; Foster, A.; Ohdera, A.; Shantz, A. A.; Burkepile, D. E.; Maynard, J. A.; Medina, M.; Vega Thurber, R.

2016-02-01

Coral reefs face increasing challenges worldwide, threatened by overfishing and nutrient pollution, which drive growth of algal competitors of corals, and periods of extreme temperature, which drive mass coral bleaching. I will discuss two projects that examine how coral's complex relationships with microorganisms affect the response of coral colonies and coral species to environmental challenge. Microbiological studies have documented key roles for coral's microbial symbionts in energy harvest and defense against pathogens. However, the evolutionary history of corals and their microbes is little studied. As part of the Global Coral Microbiome Project, we are characterizing bacterial, archaeal, fungal, and Symbiodinium diversity across >1400 DNA samples from all major groups of corals, collected from 15 locations worldwide. This collection will allow us to ask how coral- microbe associations evolved over evolutionary time, and to determine whether microbial symbiosis helps predict the relative vulnerability of certain coral species to environmental stress. In the second project, we experimentally characterized how the long-term effects of human impacts such as overfishing and nutrient pollution influence coral-microbe symbiosis. We conducted a three-year field experiment in the Florida Keys applying nutrient pollution or simulated overfishing to reef plots, and traced the effects on reef communities, coral microbiomes, and coral health. The results show that extremes of temperature and algal competition destabilize coral microbiomes, increasing pathogen blooms, coral disease, and coral death. Surprisingly, these local stressors interacted strongly with thermal stress: the greatest microbiome disruption, and >80% of coral mortality happened in the hottest periods. Thus, overfishing and nutrient pollution may interact with increased climate-driven episodes of sub-bleaching thermal stress to increase coral mortality by disrupt reef communities down to microbial scales.

Cryptic effects of habitat declines: coral-associated fishes avoid coral-seaweed interactions due to visual and chemical cues

PubMed Central

Brooker, Rohan M.; Brandl, Simon J.; Dixson, Danielle L.

2016-01-01

Seaweed-dominated coral reefs are becoming increasingly common as environmental conditions shift away from those required by corals and toward those ideal for rampant seaweed growth. How coral-associated organisms respond to seaweed will not only impact their fate following environmental change but potentially also the trajectories of the coral communities on which they rely. However, behavioral responses by coral-associated organisms to seaweeds are poorly understood. This study examined interactions between a guild of obligate and opportunistic coral-feeding butterflyfishes (Chaetodontidae) and scleractinian corals to determine whether fishes continue to interact with corals in contact with seaweed or if they are avoided. Under natural conditions, all species interacted almost exclusively with seaweed-free corals. In a controlled patch reef experiment, fishes avoided corals in physical contact with seaweed, irrespective of dietary preferences. When visual seaweed cues were removed, butterflyfish continued to avoid corals that had been in contact with the allelopathic Galaxaura filamentosa, suggesting that chemical cues produced by coral-seaweed interactions are repellent. These findings suggest that, due to deleterious visual and chemical cues produced by coral-seaweed interactions, coral-associated organisms may struggle to locate resources as seaweed-free corals decline in abundance. PMID:26725835

Transcriptomic characterization of temperature stress responses in larval zebrafish.

PubMed

Long, Yong; Li, Linchun; Li, Qing; He, Xiaozhen; Cui, Zongbin

2012-01-01

Temperature influences nearly all biochemical, physiological and life history activities of fish, but the molecular mechanisms underlying the temperature acclimation remains largely unknown. Previous studies have identified many temperature-regulated genes in adult tissues; however, the transcriptional responses of fish larvae to temperature stress are not well understood. In this study, we characterized the transcriptional responses in larval zebrafish exposed to cold or heat stress using microarray analysis. In comparison with genes expressed in the control at 28 °C, a total of 2680 genes were found to be affected in 96 hpf larvae exposed to cold (16 °C) or heat (34 °C) for 2 and 48h and most of these genes were expressed in a temperature-specific and temporally regulated manner. Bioinformatic analysis identified multiple temperature-regulated biological processes and pathways. Biological processes overrepresented among the earliest genes induced by temperature stress include regulation of transcription, nucleosome assembly, chromatin organization and protein folding. However, processes such as RNA processing, cellular metal ion homeostasis and protein transport and were enriched in genes up-regulated under cold exposure for 48 h. Pathways such as mTOR signalling, p53 signalling and circadian rhythm were enriched among cold-induced genes, while adipocytokine signalling, protein export and arginine and praline metabolism were enriched among heat-induced genes. Although most of these biological processes and pathways were specifically regulated by cold or heat, common responses to both cold and heat stresses were also found. Thus, these findings provide new interesting clues for elucidation of mechanisms underlying the temperature acclimation in fish.

Gene expression divergence between malaria vector sibling species Anopheles gambiae and An. coluzzii from rural and urban Yaoundé Cameroon

PubMed Central

Cassone, Bryan J.; Kamdem, Colince; Cheng, Changde; Tan, John C.; Hahn, Matthew W.; Costantini, Carlo; Besansky, Nora J.

2014-01-01

Divergent selection based on aquatic larval ecology is a likely factor in the recent isolation of two broadly sympatric and morphologically identical African mosquito species, the malaria vectors Anopheles gambiae and An. coluzzii. Population-based genome scans have revealed numerous candidate regions of recent positive selection, but have provided few clues as to the genetic mechanisms underlying behavioral and physiological divergence between the two species, phenotypes which themselves remain obscure. To uncover possible genetic mechanisms, we compared global transcriptional profiles of natural and experimental populations using gene-based microarrays. Larvae were sampled as second and fourth instars from natural populations in and around the city of Yaoundé, capital of Cameroon, where the two species segregate along a gradient of urbanization. Functional enrichment analysis of differentially expressed genes revealed that An. coluzzii—the species that breeds in more stable, biotically complex and potentially polluted urban water bodies—over-expresses genes implicated in detoxification and immunity relative to An. gambiae, which breeds in more ephemeral and relatively depauperate pools and puddles in suburbs and rural areas. Moreover, our data suggest that such over-expression by An. coluzzii is not a transient result of induction by xenobiotics in the larval habitat, but an inherent and presumably adaptive response to repeatedly encountered environmental stressors. Finally, we find no significant overlap between the differentially expressed loci and previously identified genomic regions of recent positive selection, suggesting that transcriptome divergence is regulated by trans-acting factors rather than cis-acting elements. PMID:24673723

A coral-on-a-chip microfluidic platform enabling live-imaging microscopy of reef-building corals.

PubMed

Shapiro, Orr H; Kramarsky-Winter, Esti; Gavish, Assaf R; Stocker, Roman; Vardi, Assaf

2016-03-04

Coral reefs, and the unique ecosystems they support, are facing severe threats by human activities and climate change. Our understanding of these threats is hampered by the lack of robust approaches for studying the micro-scale interactions between corals and their environment. Here we present an experimental platform, coral-on-a-chip, combining micropropagation and microfluidics to allow direct microscopic study of live coral polyps. The small and transparent coral micropropagates are ideally suited for live-imaging microscopy, while the microfluidic platform facilitates long-term visualization under controlled environmental conditions. We demonstrate the usefulness of this approach by imaging coral micropropagates at previously unattainable spatio-temporal resolutions, providing new insights into several micro-scale processes including coral calcification, coral-pathogen interaction and the loss of algal symbionts (coral bleaching). Coral-on-a-chip thus provides a powerful method for studying coral physiology in vivo at the micro-scale, opening new vistas in coral biology.

A Novel Highly Divergent Protein Family Identified from a Viviparous Insect by RNA-seq Analysis: A Potential Target for Tsetse Fly-Specific Abortifacients

PubMed Central

Benoit, Joshua B.; Attardo, Geoffrey M.; Michalkova, Veronika; Krause, Tyler B.; Bohova, Jana; Zhang, Qirui; Baumann, Aaron A.; Mireji, Paul O.; Takáč, Peter; Denlinger, David L.; Ribeiro, Jose M.; Aksoy, Serap

2014-01-01

In tsetse flies, nutrients for intrauterine larval development are synthesized by the modified accessory gland (milk gland) and provided in mother's milk during lactation. Interference with at least two milk proteins has been shown to extend larval development and reduce fecundity. The goal of this study was to perform a comprehensive characterization of tsetse milk proteins using lactation-specific transcriptome/milk proteome analyses and to define functional role(s) for the milk proteins during lactation. Differential analysis of RNA-seq data from lactating and dry (non-lactating) females revealed enrichment of transcripts coding for protein synthesis machinery, lipid metabolism and secretory proteins during lactation. Among the genes induced during lactation were those encoding the previously identified milk proteins (milk gland proteins 1–3, transferrin and acid sphingomyelinase 1) and seven new genes (mgp4–10). The genes encoding mgp2–10 are organized on a 40 kb syntenic block in the tsetse genome, have similar exon-intron arrangements, and share regions of amino acid sequence similarity. Expression of mgp2–10 is female-specific and high during milk secretion. While knockdown of a single mgp failed to reduce fecundity, simultaneous knockdown of multiple variants reduced milk protein levels and lowered fecundity. The genomic localization, gene structure similarities, and functional redundancy of MGP2–10 suggest that they constitute a novel highly divergent protein family. Our data indicates that MGP2–10 function both as the primary amino acid resource for the developing larva and in the maintenance of milk homeostasis, similar to the function of the mammalian casein family of milk proteins. This study underscores the dynamic nature of the lactation cycle and identifies a novel family of lactation-specific proteins, unique to Glossina sp., that are essential to larval development. The specificity of MGP2–10 to tsetse and their critical role during lactation suggests that these proteins may be an excellent target for tsetse-specific population control approaches. PMID:24763277

50 CFR 665.463 - Prohibitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Mariana precious coral MUS in any Mariana precious coral permit area, unless a permit has been issued for..., take, or retain any species of Mariana precious coral MUS in any Mariana precious coral permit area: (1...) Take and retain, possess, or land any live pink coral or live black coral from any precious coral...

50 CFR 665.463 - Prohibitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Mariana precious coral MUS in any Mariana precious coral permit area, unless a permit has been issued for..., take, or retain any species of Mariana precious coral MUS in any Mariana precious coral permit area: (1...) Take and retain, possess, or land any live pink coral or live black coral from any precious coral...

50 CFR 665.463 - Prohibitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Mariana precious coral MUS in any Mariana precious coral permit area, unless a permit has been issued for..., take, or retain any species of Mariana precious coral MUS in any Mariana precious coral permit area: (1...) Take and retain, possess, or land any live pink coral or live black coral from any precious coral...

50 CFR 665.463 - Prohibitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Mariana precious coral MUS in any Mariana precious coral permit area, unless a permit has been issued for..., take, or retain any species of Mariana precious coral MUS in any Mariana precious coral permit area: (1...) Take and retain, possess, or land any live pink coral or live black coral from any precious coral...

50 CFR 665.463 - Prohibitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Mariana precious coral MUS in any Mariana precious coral permit area, unless a permit has been issued for..., take, or retain any species of Mariana precious coral MUS in any Mariana precious coral permit area: (1...) Take and retain, possess, or land any live pink coral or live black coral from any precious coral...

Contact with turf algae alters the coral microbiome: contact versus systemic impacts

NASA Astrophysics Data System (ADS)

Pratte, Zoe A.; Longo, Guilherme O.; Burns, Andrew S.; Hay, Mark E.; Stewart, Frank J.

2018-03-01

Coral reefs are degrading to algae-dominated reefs worldwide, with alterations of coral microbiomes commonly co-occurring with reef demise. The severe thermal anomaly during the 2016 El Niño event in the South Pacific killed many corals and stressed others. We examined the microbiome of turf algae and of the coral Porites sp. in contact with turf during this thermal event to investigate algal turf effects on the coral microbiome during a period of environmental stress. The microbial composition of turf did not differ between coral-contacted and non-contacted turfs. However, microbiomes of corals in direct contact with turf were similar to those of the turf microbiome, but differed significantly from coral portions 5 cm from the point of turf/coral contact and from portions of the coral that looked most healthy, regardless of location. Although the majority of significant differences occurred in coral samples at the point of contact, a small subset of microbial taxa was enriched in coral tissues taken 5 cm from turf contact compared to all other sample types, including samples from areas of the coral that appeared most healthy. These results suggest that the coral microbiome is susceptible to colonization by microbes from turf, but not vice versa. Results also suggest that algal contact elicits a subtle shift in the coral microbiome just beyond the contact site. The combination of turf microbiome stability and coral microbiome vulnerability at areas of contact may contribute to the continued decline in coral cover and increase in algal cover associated with coral-algae phase shifts.

Horizontal transmission of Symbiodinium cells between adult and juvenile corals is aided by benthic sediment

NASA Astrophysics Data System (ADS)

Nitschke, Matthew R.; Davy, Simon K.; Ward, Selina

2016-03-01

Of all reef-building coral species, 80-85 % initially draw their intracellular symbionts (dinoflagellates of the genus Symbiodinium) from the environment. Although Symbiodinium cells are crucial for the growth of corals and the formation of coral reefs, little is known about how corals first encounter free-living Symbiodinium cells. We report how the supply of free-living Symbiodinium cells to the benthos by adult corals can increase the rate of horizontal symbiont acquisition for conspecific recruits. Three species of newly settled aposymbiotic (i.e., symbiont-free) corals were maintained in an open aquarium system containing: sterilized sediment and adult coral fragments combined; adult coral fragments alone; sterilized sediment alone; or seawater at Heron Island, Great Barrier Reef, Australia. In all instances, the combination of an adult coral and sediment resulted in the highest symbiont acquisition rates by juvenile corals (up to five-fold greater than seawater alone). Juvenile corals exposed to individual treatments of adult coral or sediment produced an intermediate acquisition response (<52 % of recruits), and symbiont acquisition from unfiltered seawater was comparatively low (<20 % of recruits). Additionally, benthic free-living Symbiodinium cells reached their highest densities in the adult coral + sediment treatment (up to 1.2 × 104 cells mL-1). Our results suggest that corals seed microhabitats with free-living Symbiodinium cells suitable for many coral species during the process of coral recruitment.

[Progress of heterotrophic studies on symbiotic corals].

PubMed

Yang, Yang-Chu-Qiao; Hong, Wen Ting; Wang, Shu Hong

2017-12-01

Heterotrophy of zooxanthellae symbiotic corals refers to the nutrition directly coming from food absorption, not the nutrition obtained from photosynthesis. Most ex situ propagation of symbiotic corals focused on the effects of irradiation, flow rate and water quality on corals, few of them involved in the demand and supply of coral heterotrophic nutrition. This paper reviewed the significance of heterotrophic nutrient supply to symbiotic corals from the sources of coral heterotrophic nutrition, the factors affecting the supply of coral heterotrophic nutrient, and the methods of how to study the coral heterotrophy. In general, the research of coral heterotrophy is just at the beginning stage, and future studies should focus on the inherent mechanism of coral feeding selection and developing more effective research methods.

50 CFR 665.663 - Prohibitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., possess or land PRIA precious coral MUS in any precious coral permit area, unless a permit has been issued..., take, or retain any species of PRIA precious coral MUS in any precious coral permit area: (1) By means... retain, possess, or land any live pink coral or live black coral from any precious coral permit area that...

50 CFR 665.663 - Prohibitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., possess or land PRIA precious coral MUS in any precious coral permit area, unless a permit has been issued..., take, or retain any species of PRIA precious coral MUS in any precious coral permit area: (1) By means... retain, possess, or land any live pink coral or live black coral from any precious coral permit area that...

50 CFR 665.163 - Prohibitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... precious coral in any precious coral permit area, unless a permit has been issued for that vessel and area... species of American Samoa precious coral MUS in any precious coral permit area: (1) By means of gear or... land any live pink coral or live black coral from any precious coral permit area that is less than the...

50 CFR 665.163 - Prohibitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... precious coral in any precious coral permit area, unless a permit has been issued for that vessel and area... species of American Samoa precious coral MUS in any precious coral permit area: (1) By means of gear or... land any live pink coral or live black coral from any precious coral permit area that is less than the...

50 CFR 665.163 - Prohibitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... precious coral in any precious coral permit area, unless a permit has been issued for that vessel and area... species of American Samoa precious coral MUS in any precious coral permit area: (1) By means of gear or... land any live pink coral or live black coral from any precious coral permit area that is less than the...

50 CFR 665.163 - Prohibitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... precious coral in any precious coral permit area, unless a permit has been issued for that vessel and area... species of American Samoa precious coral MUS in any precious coral permit area: (1) By means of gear or... land any live pink coral or live black coral from any precious coral permit area that is less than the...