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Sample records for larval dispersal connects

  1. Modeling larval connectivity of the Atlantic surfclams within the Middle Atlantic Bight: Model development, larval dispersal and metapopulation connectivity

    NASA Astrophysics Data System (ADS)

    Zhang, Xinzhong; Haidvogel, Dale; Munroe, Daphne; Powell, Eric N.; Klinck, John; Mann, Roger; Castruccio, Frederic S.

    2015-02-01

    To study the primary larval transport pathways and inter-population connectivity patterns of the Atlantic surfclam, Spisula solidissima, a coupled modeling system combining a physical circulation model of the Middle Atlantic Bight (MAB), Georges Bank (GBK) and the Gulf of Maine (GoM), and an individual-based surfclam larval model was implemented, validated and applied. Model validation shows that the model can reproduce the observed physical circulation patterns and surface and bottom water temperature, and recreates the observed distributions of surfclam larvae during upwelling and downwelling events. The model results show a typical along-shore connectivity pattern from the northeast to the southwest among the surfclam populations distributed from Georges Bank west and south along the MAB shelf. Continuous surfclam larval input into regions off Delmarva (DMV) and New Jersey (NJ) suggests that insufficient larval supply is unlikely to be the factor causing the failure of the population to recover after the observed decline of the surfclam populations in DMV and NJ from 1997 to 2005. The GBK surfclam population is relatively more isolated than populations to the west and south in the MAB; model results suggest substantial inter-population connectivity from southern New England to the Delmarva region. Simulated surfclam larvae generally drift for over one hundred kilometers along the shelf, but the distance traveled is highly variable in space and over time. Surfclam larval growth and transport are strongly impacted by the physical environment. This suggests the need to further examine how the interaction between environment, behavior, and physiology affects inter-population connectivity. Larval vertical swimming and sinking behaviors have a significant net effect of increasing larval drifting distances when compared with a purely passive model, confirming the need to include larval behavior.

  2. BOLTS: a BiOphysical Larval Tracking System for Measuring Dispersal Characteristics and Marine Population Connectivity

    NASA Astrophysics Data System (ADS)

    Paris, C. B.; Srinivasan, A.; Kourafalou, V.; Sponaugle, S.; Cowen, R. K.

    2008-12-01

    While metapopulation research with hypothetical dispersal matrices has shown how the scales of larval dispersal, transport processes, local recruitment, and temporal and spatial variability in dispersal influence population persistence, the pattern of demographic connectivity produced by larval dispersal is still a key uncertainty. To address this problem, a coupled bio-physical model has been developed that quantifies the degree of connectivity between populations. Such spatially explicit models, forced by dynamic currents coupled to a realistic seascape and life history traits, produce dispersal kernels for a range of scales over which dispersal is practically unquantifiable by current empirical methods. The BiOphysical Larval Tracking System (BOLTS) presented here allows a Lagrangian stochastic individual-based model (IBM) to be coupled via OPENDAP framework to any 3-dimensional fields of circulation models including to domains of various resolutions through 'Lagrangian nesting'. We demonstrate the capabilities of the software in measuring the characteristics of dispersal and evaluating the variability of larval connectivity through two examples at different scales: 1) Caribbean-scale simulations of BOLTS using the large scale (resolution ~7 km) Hybrid Coordinate Ocean Model (HYCOM) from the Global Data Assimilative Experiment (GODAE) provide us with expected connectivity patterns of a reef building coral. By seeding the model with a large number of active particles, it is possible to assemble dispersal kernels and migration matrices from the start (spawning) and the end point (settlement) of individual particle trajectories. Any single run is a stochastic realization of a probabilistic process, thus the full probability density function (pdf) of the kernel requires averaging over many dispersal events. The model output is further corroborated with empirical measures of gene flow among coral colonies around the Caribbean. 2) Coastal-scale simulations of BOLTS

  3. Larval dispersal underlies demographically important inter-system connectivity in a Great Lakes yellow perch (Perca flavescens) population

    USGS Publications Warehouse

    Brodnik, Reed M.; Fraker, Michael E.; Anderson, Eric J.; Carreon-Martinez, Lucia; DeVanna, Kristen M.; Heath, Dan D.; Reichert, Julie M.; Roseman, Edward F.; Ludsin, Stuart A.

    2016-01-01

    Ability to quantify connectivity among spawning subpopulations and their relative contribution of recruits to the broader population is a critical fisheries management need. By combining microsatellite and age information from larval yellow perch (Perca flavescens) collected in the Lake St. Clair – Detroit River system (SC-DRS) and western Lake Erie with a hydrodynamic backtracking approach, we quantified subpopulation structure, connectivity, and contributions of recruits to the juvenile stage in western Lake Erie during 2006-2007. After finding weak (yet stable) genetic structure between the SC-DRS and two western Lake Erie subpopulations, microsatellites also revealed measurable recruitment of SC-DRS larvae to the juvenile stage in western Lake Erie (17-21% during 2006-2007). Consideration of pre-collection larval dispersal trajectories, using hydrodynamic backtracking, increased estimated contributions to 65% in 2006 and 57% in 2007. Our findings highlight the value of complementing subpopulation discrimination methods with hydrodynamic predictions of larval dispersal by revealing the SC-DRS as a source of recruits to western Lake Erie and also showing that connectivity through larval dispersal can affect the structure and dynamics of large-lake fish populations.

  4. Inverse approach to estimating larval dispersal reveals limited population connectivity along 700 km of wave-swept open coast.

    PubMed

    Hameed, Sarah O; White, J Wilson; Miller, Seth H; Nickols, Kerry J; Morgan, Steven G

    2016-06-29

    Demographic connectivity is fundamental to the persistence and resilience of metapopulations, but our understanding of the link between reproduction and recruitment is notoriously poor in open-coast marine populations. We provide the first evidence of high local retention and limited connectivity among populations spanning 700 km along an open coast in an upwelling system. Using extensive field measurements of fecundity, population size and settlement in concert with a Bayesian inverse modelling approach, we estimated that, on average, Petrolisthes cinctipes larvae disperse only 6.9 km (±25.0 km s.d.) from natal populations, despite spending approximately six weeks in an open-coast system that was once assumed to be broadly dispersive. This estimate differed substantially from our prior dispersal estimate (153.9 km) based on currents and larval duration and behaviour, revealing the importance of employing demographic data in larval dispersal estimates. Based on this estimate, we predict that demographic connectivity occurs predominantly among neighbouring populations less than 30 km apart. Comprehensive studies of larval production, settlement and connectivity are needed to advance an understanding of the ecology and evolution of life in the sea as well as to conserve ecosystems. Our novel approach provides a tractable framework for addressing these questions for species occurring in discrete coastal populations. PMID:27358362

  5. Modeling larval dispersal and quantifying coastal connectivity based on a downscaling ocean model in Seto Inland Sea, Japan

    NASA Astrophysics Data System (ADS)

    Kosako, T.; Uchiyama, Y.; Mitarai, S.

    2014-12-01

    Connectivity is defined as the probability that particles leaving a source patch (spawning site) arrive at a sink patch (settling ground) for a given advection time. It can measure stochastic processes of a wide range of larval dispersal due to chaotic coastal circulations (e.g., Mitarai et al., 2009). The present study aims at investigating larval networks in Seto Inland Sea (SIS), an about 450-km long, semi-enclosed, estuarine tidal channel connected to Kuroshio drifting off the two openings of SIS. We quantify coastal connectivity using Lagrangian PDFs of enormous amount of Lagrangian particles released in the modeled SIS circulation field in a double nested configuration based on ROMS at the horizontal grid spacing of 600 m (Uchiyama et al., 2012). The particles are released twice a day from 140 source patches with a radius of 5 km for 2 months in the winter 2011, and integrated over the advection time of 30 days, mimicking spawning and pelagic larvae of marbled sole. The Lagrangian PDFs and the associated connectivity patterns are found to be generally heterogeneous. The connectivity matrices successively depict the larval networks in SIS. We separate SIS into 8 subregions (i.e., bays) to determine the networks among them. The fraction of the particles that exit to another region is about less than 40% except for the two entrance subregions, suggesting the intra-subregional transport is predominant. However, the particles are gradually transported eastward due to the residual mean clockwise circulation of SIS. We then evaluate the larval dispersal of marbled sole in a subregion, Harima Nada (HN). Destination strength shows that particles released in HN are mainly transported towards the northern shore of Shodo Island, and source strength indicates that the particles arriving there originate primarily from the western shore of HN. Those results suggest a potential utility of the ocean model-derived connectivity to quantify the larval networks in estuaries.

  6. 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

  7. Larval connectivity and the international management of fisheries.

    PubMed

    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

  8. Patterns, causes, and consequences of marine larval dispersal

    PubMed Central

    D’Aloia, Cassidy C.; Bogdanowicz, Steven M.; Francis, Robin K.; Majoris, John E.; Harrison, Richard G.; Buston, Peter M.

    2015-01-01

    Quantifying the probability of larval exchange among marine populations is key to predicting local population dynamics and optimizing networks of marine protected areas. The pattern of connectivity among populations can be described by the measurement of a dispersal kernel. However, a statistically robust, empirical dispersal kernel has been lacking for any marine species. Here, we use genetic parentage analysis to quantify a dispersal kernel for the reef fish Elacatinus lori, demonstrating that dispersal declines exponentially with distance. The spatial scale of dispersal is an order of magnitude less than previous estimates—the median dispersal distance is just 1.7 km and no dispersal events exceed 16.4 km despite intensive sampling out to 30 km from source. Overlaid on this strong pattern is subtle spatial variation, but neither pelagic larval duration nor direction is associated with the probability of successful dispersal. Given the strong relationship between distance and dispersal, we show that distance-driven logistic models have strong power to predict dispersal probabilities. Moreover, connectivity matrices generated from these models are congruent with empirical estimates of spatial genetic structure, suggesting that the pattern of dispersal we uncovered reflects long-term patterns of gene flow. These results challenge assumptions regarding the spatial scale and presumed predictors of marine population connectivity. We conclude that if marine reserve networks aim to connect whole communities of fishes and conserve biodiversity broadly, then reserves that are close in space (<10 km) will accommodate those members of the community that are short-distance dispersers. PMID:26508628

  9. Larval connectivity in an effective network of marine protected areas.

    PubMed

    Christie, Mark R; Tissot, Brian N; Albins, Mark A; Beets, James P; Jia, Yanli; Ortiz, Delisse M; Thompson, Stephen E; Hixon, Mark A

    2010-01-01

    Acceptance of marine protected areas (MPAs) as fishery and conservation tools has been hampered by lack of direct evidence that MPAs successfully seed unprotected areas with larvae of targeted species. For the first time, we present direct evidence of large-scale population connectivity within an existing and effective network of MPAs. A new parentage analysis identified four parent-offspring pairs from a large, exploited population of the coral-reef fish Zebrasoma flavescens in Hawai'i, revealing larval dispersal distances ranging from 15 to 184 km. In two cases, successful dispersal was from an MPA to unprotected sites. Given high adult abundances, the documentation of any parent-offspring pairs demonstrates that ecologically-relevant larval connectivity between reefs is substantial. All offspring settled at sites to the north of where they were spawned. Satellite altimetry and oceanographic models from relevant time periods indicated a cyclonic eddy that created prevailing northward currents between sites where parents and offspring were found. These findings empirically demonstrate the effectiveness of MPAs as useful conservation and management tools and further highlight the importance of coupling oceanographic, genetic, and ecological data to predict, validate and quantify larval connectivity among marine populations. PMID:21203576

  10. Connectivity in the Intra-American Seas and implications for potential larval transport

    NASA Astrophysics Data System (ADS)

    Qian, H.; Li, Y.; He, R.; Eggleston, D. B.

    2015-06-01

    A major challenge in marine ecology is to describe patterns of larval dispersal and population connectivity, as well as their underlying processes. We re-assessed broad-scale population connectivity with a focus on the 18 coral reef hot spots in the Intra-American Seas described in Roberts (Science 278:1454-1457, 1997), by including seasonal and inter-annual variability in potential larval dispersal. While overall dispersal patterns were in agreement with previous findings, further statistical analyses show that dispersal patterns driven by mean circulation initially described by Roberts (Science 278:1454-1457, 1997) can significantly underestimate particle connectivity envelopes. The results from this study indicate that seasonal and inter-annual variability in circulation are crucial in modulating both dispersal distance and directional anisotropy of virtual larvae over most coral reef sites and that certain larval hotspots are likely more strongly connected than originally thought. Improved larval dispersal transport envelopes can enhance the accuracy of probability estimates which, in turn, may help to explain episodic larval settlement in certain times and places, and guide spatial management such as marine protected areas.

  11. Complex larval connectivity patterns among marine invertebrate populations

    PubMed Central

    Becker, Bonnie J.; Levin, Lisa A.; Fodrie, F. Joel; McMillan, Pat A.

    2007-01-01

    Based on the belief that marine larvae, which can spend days to months in the planktonic stage, could be transported considerable distances by ocean currents, it has long been assumed that populations of coastal species with a planktonic larval stage are demographically open and highly “connected.” Such assumptions about the connectivity of coastal populations govern approaches to managing marine resources and shape our fundamental understanding of population dynamics and evolution, yet are rarely tested directly due to the small size and high mortality of marine larvae in a physically complex environment. Here, we document a successful application of elemental fingerprinting as a tracking tool to determine sources of settled invertebrates and show that coastal mussel larvae, previously thought to be highly dispersed, can be retained within 20–30 km of their natal origin. We compare two closely related and co-occurring species, Mytilus californianus and Mytilus galloprovincialis, and determine that, despite expected similarities, they exhibit substantially different connectivity patterns. Our use of an in situ larval culturing technique overcomes the previous challenge of applying microchemical tracking methods to species with completely planktonic development. The exchange of larvae and resulting connectivities among marine populations have fundamental consequences for the evolution and ecology of species and for the management of coastal resources. PMID:17360636

  12. Larval retention and connectivity among populations of corals and reef fishes: history, advances and challenges

    NASA Astrophysics Data System (ADS)

    Jones, G. P.; Almany, G. R.; Russ, G. R.; Sale, P. F.; Steneck, R. S.; van Oppen, M. J. H.; Willis, B. L.

    2009-06-01

    The extent of larval dispersal on coral reefs has important implications for the persistence of coral reef metapopulations, their resilience and recovery from an increasing array of threats, and the success of protective measures. This article highlights a recent dramatic increase in research effort and a growing diversity of approaches to the study of larval retention within (self-recruitment) and dispersal among (connectivity) isolated coral reef populations. Historically, researchers were motivated by alternative hypotheses concerning the processes limiting populations and structuring coral reef assemblages, whereas the recent impetus has come largely from the need to incorporate dispersal information into the design of no-take marine protected area (MPA) networks. Although the majority of studies continue to rely on population genetic approaches to make inferences about dispersal, a wide range of techniques are now being employed, from small-scale larval tagging and paternity analyses, to large-scale biophysical circulation models. Multiple approaches are increasingly being applied to cross-validate and provide more realistic estimates of larval dispersal. The vast majority of empirical studies have focused on corals and fishes, where evidence for both extremely local scale patterns of self-recruitment and ecologically significant connectivity among reefs at scales of tens of kilometers (and in some cases hundreds of kilometers) is accumulating. Levels of larval retention and the spatial extent of connectivity in both corals and fishes appear to be largely independent of larval duration or reef size, but may be strongly influenced by geographic setting. It is argued that high levels of both self-recruitment and larval import can contribute to the resilience of reef populations and MPA networks, but these benefits will erode in degrading reef environments.

  13. Larval Dispersal Modeling of Pearl Oyster Pinctada margaritifera following Realistic Environmental and Biological Forcing in Ahe Atoll Lagoon

    PubMed Central

    Thomas, Yoann; Dumas, Franck; Andréfouët, Serge

    2014-01-01

    Studying the larval dispersal of bottom-dwelling species is necessary to understand their population dynamics and optimize their management. The black-lip pearl oyster (Pinctada margaritifera) is cultured extensively to produce black pearls, especially in French Polynesia's atoll lagoons. This aquaculture relies on spat collection, a process that can be optimized by understanding which factors influence larval dispersal. Here, we investigate the sensitivity of P. margaritifera larval dispersal kernel to both physical and biological factors in the lagoon of Ahe atoll. Specifically, using a validated 3D larval dispersal model, the variability of lagoon-scale connectivity is investigated against wind forcing, depth and location of larval release, destination location, vertical swimming behavior and pelagic larval duration (PLD) factors. The potential connectivity was spatially weighted according to both the natural and cultivated broodstock densities to provide a realistic view of connectivity. We found that the mean pattern of potential connectivity was driven by the southwest and northeast main barotropic circulation structures, with high retention levels in both. Destination locations, spawning sites and PLD were the main drivers of potential connectivity, explaining respectively 26%, 59% and 5% of the variance. Differences between potential and realistic connectivity showed the significant contribution of the pearl oyster broodstock location to its own dynamics. Realistic connectivity showed larger larval supply in the western destination locations, which are preferentially used by farmers for spat collection. In addition, larval supply in the same sectors was enhanced during summer wind conditions. These results provide new cues to understanding the dynamics of bottom-dwelling populations in atoll lagoons, and show how to take advantage of numerical models for pearl oyster management. PMID:24740288

  14. Model-Derived Dispersal Pathways from Multiple Source Populations Explain Variability of Invertebrate Larval Supply

    PubMed Central

    Domingues, Carla P.; Nolasco, Rita; Dubert, Jesus; Queiroga, Henrique

    2012-01-01

    Background Predicting the spatial and temporal patterns of marine larval dispersal and supply is a challenging task due to the small size of the larvae and the variability of oceanographic processes. Addressing this problem requires the use of novel approaches capable of capturing the inherent variability in the mechanisms involved. Methodology/Principal Findings In this study we test whether dispersal and connectivity patterns generated from a bio-physical model of larval dispersal of the crab Carcinus maenas, along the west coast of the Iberian Peninsula, can predict the highly variable daily pattern of wind-driven larval supply to an estuary observed during the peak reproductive season (March–June) in 2006 and 2007. Cross-correlations between observed and predicted supply were significant (p<0.05) and strong, ranging from 0.34 to 0.81 at time lags of −6 to +5 d. Importantly, the model correctly predicted observed cross-shelf distributions (Pearson r = 0.82, p<0.001, and r = 0.79, p<0.01, in 2006 and 2007) and indicated that all supply events were comprised of larvae that had been retained within the inner shelf; larvae transported to the outer shelf and beyond never recruited. Estimated average dispersal distances ranged from 57 to 198 km and were only marginally affected by mortality. Conclusions/Significance The high degree of predicted demographic connectivity over relatively large geographic scales is consistent with the lack of genetic structuring in C. maenas along the Iberian Peninsula. These findings indicate that the dynamic nature of larval dispersal can be captured by mechanistic biophysical models, which can be used to provide meaningful predictions of the patterns and causes of fine-scale variability in larval supply to marine populations. PMID:22558225

  15. The relative effect of behaviour in larval dispersal in a low energy embayment

    NASA Astrophysics Data System (ADS)

    Daigle, Rémi M.; Chassé, Joël; Metaxas, Anna

    2016-05-01

    This study examined the relative importance of tidal phase, larval behaviour, release site, depth layer, and vertical swimming velocity on mean in-sea dispersal distance, retention, distance from shore, and population connectivity. Using a biophysical model, we simulated larval dispersal of marine benthic invertebrates for 6 taxonomic groups representing different combinations of swimming speed, and depth preference in St. George's Bay, NS, Canada, a shallow bay with low energy (e.g. lack of estuarine circulation). The biophysical model was run over a period of 3 months, from Jul to Sep, representing the period when larvae of the targeted species were present, and at each of 3 years. Overall, release site had the strongest effect of all factors on the dispersal metrics. Although less important than release site in our system, vertical distribution and swim speed had a significant effect which would likely be more pronounced in high (i.e. with features such as estuarine circulation or internal waves) than low energy environments. Retention and distance from shore were more responsive to our manipulations than dispersal distance, both in terms of the number of ecologically significant effects and the magnitudes of their effect size. These findings allow for the prioritization of biophysical model parameters and improved simulations of larval dispersal.

  16. Rapid effects of marine reserves via larval dispersal.

    PubMed

    Cudney-Bueno, Richard; Lavín, Miguel F; Marinone, Silvio G; Raimondi, Peter T; Shaw, William W

    2009-01-01

    Marine reserves have been advocated worldwide as conservation and fishery management tools. It is argued that they can protect ecosystems and also benefit fisheries via density-dependent spillover of adults and enhanced larval dispersal into fishing areas. However, while evidence has shown that marine reserves can meet conservation targets, their effects on fisheries are less understood. In particular, the basic question of if and over what temporal and spatial scales reserves can benefit fished populations via larval dispersal remains unanswered. We tested predictions of a larval transport model for a marine reserve network in the Gulf of California, Mexico, via field oceanography and repeated density counts of recently settled juvenile commercial mollusks before and after reserve establishment. We show that local retention of larvae within a reserve network can take place with enhanced, but spatially-explicit, recruitment to local fisheries. Enhancement occurred rapidly (2 yrs), with up to a three-fold increase in density of juveniles found in fished areas at the downstream edge of the reserve network, but other fishing areas within the network were unaffected. These findings were consistent with our model predictions. Our findings underscore the potential benefits of protecting larval sources and show that enhancement in recruitment can be manifested rapidly. However, benefits can be markedly variable within a local seascape. Hence, effects of marine reserve networks, positive or negative, may be overlooked when only focusing on overall responses and not considering finer spatially-explicit responses within a reserve network and its adjacent fishing grounds. Our results therefore call for future research on marine reserves that addresses this variability in order to help frame appropriate scenarios for the spatial management scales of interest. PMID:19129910

  17. Strengthened currents override the effect of warming on lobster larval dispersal and survival.

    PubMed

    Cetina-Heredia, Paulina; Roughan, Moninya; van Sebille, Erik; Feng, Ming; Coleman, Melinda A

    2015-12-01

    Human-induced climate change is projected to increase ocean temperature and modify circulation patterns, with potential widespread implications for the transport and survival of planktonic larvae of marine organisms. Circulation affects the dispersal of larvae, whereas temperature impacts larval development and survival. However, the combined effect of changes in circulation and temperature on larval dispersal and survival has rarely been studied in a future climate scenario. Such understanding is crucial to predict future species distributions, anticipate ecosystem shifts and design effective management strategies. We simulate contemporary (1990s) and future (2060s) dispersal of lobster larvae using an eddy-resolving ocean model in south-eastern Australia, a region of rapid ocean warming. Here we show that the effects of changes in circulation and temperature can counter each other: ocean warming favours the survival of lobster larvae, whereas a strengthened western boundary current diminishes the supply of larvae to the coast by restricting cross-current larval dispersal. Furthermore, we find that changes in circulation have a stronger effect on connectivity patterns of lobster larvae along south-eastern Australia than ocean warming in the future climate so that the supply of larvae to the coast reduces by ~4% and the settlement peak shifts poleward by ~270 km in the model simulation. Thus, ocean circulation may be one of the dominant factors contributing to climate-induced changes of species ranges. PMID:26268457

  18. Gene flow by larval dispersal in the Antarctic notothenioid fish Gobionotothen gibberifrons.

    PubMed

    Matschiner, Michael; Hanel, Reinhold; Salzburger, Walter

    2009-06-01

    The diversification of the teleost suborder Notothenioidei (Perciformes) in Antarctic waters provides one of the most striking examples of a marine adaptive radiation. Along with a number of adaptations to the cold environment, such as the evolution of antifreeze glycoproteins, notothenioids diversified into eight families and at least 130 species. Here, we investigate the genetic population structure of the humped rockcod (Gobionotothen gibberifrons), a benthic notothenioid fish. Six populations were sampled at different locations around the Scotia Sea, comprising a large part of the species' distribution range (N = 165). Our analyses based on mitochondrial DNA sequence data (352 bp) and eight microsatellite markers reveal a lack of genetic structuring over large geographic distances (Phi(ST) < or = 0.058, F(ST) < or = 0.005, P values nonsignificant). In order to test whether this was due to passive larval dispersal, we used GPS-tracked drifter trajectories, which approximate movement of passive surface particles with ocean currents. The drifter data indicate that the Antarctic Circumpolar Current (ACC) connects the sampling locations in one direction only (west-east), and that passive transport is possible within the 4-month larval period of G. gibberifrons. Indeed, when applying the isolation-with-migration model in IMA, strong unidirectional west-east migration rates are detected in the humped rockcod. This leads us to conclude that, in G. gibberifrons, genetic differentiation is prevented by gene flow via larval dispersal with the ACC. PMID:19457182

  19. Larval dispersal drives trophic structure across Pacific coral reefs.

    PubMed

    Stier, Adrian C; Hein, Andrew M; Parravicini, Valeriano; Kulbicki, Michel

    2014-01-01

    Top predators are a critical part of healthy ecosystems. Yet, these species are often absent from spatially isolated habitats leading to the pervasive view that fragmented ecological communities collapse from the top down. Here we study reef fish from coral reef communities across the Pacific Ocean. Our analysis shows that species richness of reef fish top predators is relatively stable across habitats that vary widely in spatial isolation and total species richness. In contrast, species richness of prey reef fish declines rapidly with increasing isolation. By consequence, species-poor communities from isolated islands have three times as many predator species per prey species as near-shore communities. We develop and test a colonization-extinction model to reveal how larval dispersal patterns shape this ocean-scale gradient in trophic structure. PMID:25412873

  20. Larval abundance and dispersal at deep-sea hydrothermal vents in the southern Mariana Trough

    NASA Astrophysics Data System (ADS)

    Beaulieu, S. E.; Watanabe, H.; Mills, S. W.; Pradillon, F.; Kojima, S.; Mullineaux, L. S.

    2010-12-01

    Since the discovery of deep-sea hydrothermal vents over thirty years ago, scientists have been perplexed by the question: “How are the faunal populations established and maintained at these very discrete and often ephemeral habitats?” For the animals that are sessile or have limited mobility as adults, dispersal to these habitats occurs early in the life cycle, as planktonic larvae in the water column. Due to the difficulties in sampling deep-sea larvae, including low abundances (dilute concentrations), we have very few quantitative estimates of larval dispersal between or larval supply to hydrothermal vents. Here, we will present results of an international, collaborative effort to study larval abundance and dispersal at vents near the back-arc spreading center in the southern Mariana Trough. On R/V Yokosuka cruise YK10-11 in September 2010, we will deploy large-volume plankton pumps at approximately 3000-m depth at Snail (also called South Backarc), Archaean, and Pika, three of the Vents (Volcanic) Unit sites in the U.S. Marianas Trench Marine National Monument. These vents are being studied as part of the Japanese multi-disciplinary program TAIGA (Trans-crustal Advection and In-situ biogeochemical proceses of Global sub-sea floor Aquifer). These will be the first collections of vent larvae in the Mariana back-arc, and we will compare the abundances and diversity of larvae to similar work conducted at the Ridge 2000 East Pacific Rise Integrated Studies Site. We will deploy a current meter near the Snail site (on-axis) for preliminary estimates of passive larval transport on the time scale of the cruise. The three study sites are situated in a line perpendicular to the back-arc spreading axis, and thus may be interesting in terms of local dispersal processes. Perhaps more interesting, however, is that the back-arc vents that we will visit are as close as 25 km to known vents on the arc, yet 600 km south of the other known vents in the back-arc. These two

  1. Spatial and temporal patterns of larval dispersal in a coral-reef fish metapopulation: evidence of variable reproductive success.

    PubMed

    Pusack, Timothy J; Christie, Mark R; Johnson, Darren W; Stallings, Christopher D; Hixon, Mark A

    2014-07-01

    Many marine organisms can be transported hundreds of kilometres during their pelagic larval stage, yet little is known about spatial and temporal patterns of larval dispersal. Although traditional population-genetic tools can be applied to infer movement of larvae on an evolutionary timescale, large effective population sizes and high rates of gene flow present serious challenges to documenting dispersal patterns over shorter, ecologically relevant, timescales. Here, we address these challenges by combining direct parentage analysis and indirect genetic analyses over a 4-year period to document spatial and temporal patterns of larval dispersal in a common coral-reef fish: the bicolour damselfish (Stegastes partitus). At four island locations surrounding Exuma Sound, Bahamas, including a long-established marine reserve, we collected 3278 individuals and genotyped them at 10 microsatellite loci. Using Bayesian parentage analysis, we identified eight parent-offspring pairs, thereby directly documenting dispersal distances ranging from 0 km (i.e., self-recruitment) to 129 km (i.e., larval connectivity). Despite documenting substantial dispersal and gene flow between islands, we observed more self-recruitment events than expected if the larvae were drawn from a common, well-mixed pool (i.e., a completely open population). Additionally, we detected both spatial and temporal variation in signatures of sweepstakes and Wahlund effects. The high variance in reproductive success (i.e., 'sweepstakes') we observed may be influenced by seasonal mesoscale gyres present in the Exuma Sound, which play a prominent role in shaping local oceanographic patterns. This study documents the complex nature of larval dispersal in a coral-reef fish, and highlights the importance of sampling multiple cohorts and coupling both direct and indirect genetic methods in order disentangle patterns of dispersal, gene flow and variable reproductive success. PMID:24917250

  2. Consequences of variable larval dispersal pathways and resulting phenotypic mixtures to the dynamics of marine metapopulations

    PubMed Central

    Shima, Jeffrey S.; Noonburg, Erik G.; Swearer, Stephen E.

    2015-01-01

    Larval dispersal can connect distant subpopulations, with important implications for marine population dynamics and persistence, biodiversity conservation and fisheries management. However, different dispersal pathways may affect the final phenotypes, and thus the performance and fitness of individuals that settle into subpopulations. Using otolith microchemical signatures that are indicative of ‘dispersive’ larvae (oceanic signatures) and ‘non-dispersive’ larvae (coastal signatures), we explore the population-level consequences of dispersal-induced variability in phenotypic mixtures for the common triplefin (a small reef fish). We evaluate lipid concentration and otolith microstructure and find that ‘non-dispersive’ larvae (i) have greater and less variable lipid reserves at settlement (and this variability attenuates at a slower rate), (ii) grow faster after settlement, and (iii) experience similar carry-over benefits of lipid reserves on post-settlement growth relative to ‘dispersive’ larvae. We then explore the consequences of phenotypic mixtures in a metapopulation model with two identical subpopulations replenished by variable contributions of ‘dispersive’ and ‘non-dispersive’ larvae and find that the resulting phenotypic mixtures can have profound effects on the size of the metapopulation. We show that, depending upon the patterns of connectivity, phenotypic mixtures can lead to larger metapopulations, suggesting dispersal-induced demographic heterogeneity may facilitate metapopulation persistence. PMID:25673001

  3. 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

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

    PubMed

    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

  5. Genetic population structure of the endemic fourline wrasse (Larabicus quadrilineatus) suggests limited larval dispersal distances in the Red Sea.

    PubMed

    Froukh, Tawfiq; Kochzius, Marc

    2007-04-01

    The connectivity among marine populations is determined by the dispersal capabilities of adults as well as their eggs and larvae. Dispersal distances and directions have a profound effect on gene flow and genetic differentiation within species. Genetic homogeneity over large areas is a common feature of coral reef fishes and can reflect high dispersal capability resulting in high levels of gene flow. If fish larvae return to their parental reef, gene flow would be restricted and genetic differentiation could occur. Larabicus quadrilineatus (Labridae) is considered as an endemic fish species of the Red Sea and Gulf of Aden. The juveniles of this species are cleaner fish that feed on ectoparasites of other fishes. Here, we investigated the genetic population structure and gene flow in L. quadrilineatus among five locations in the Red Sea to infer connectivity among them. To estimate genetic diversity, we analysed 369 bp of 237 mitochondrial DNA control region sequences. Haplotype and nucleotide diversities were higher in the southern than in the northern Red Sea. Analysis of molecular variance (amova) detected the highest significant genetic variation between northern and central/southern populations (Phi(CT) = 0.01; P < 0.001). Migration analysis revealed a several fold higher northward than southward migration, which could be explained by oceanographic conditions and spawning season. Even though the Phi(ST) value of 0.01 is rather low and implies a long larval dispersal distance, estimates based on the isolation-by-distance model show a very low mean larval dispersal distance (0.44-5.1 km) compared to other studies. In order to enable a sustainable ornamental fishery on the fourline wrasse, the results of this study suggest that populations in the northern and southern Red Sea should be managed separately as two different stocks. The rather low larval dispersal distance of about 5 km needs to be considered in the design of marine protected areas to enable

  6. Reduced genetic diversity and increased reproductive isolation follow population-level loss of larval dispersal in a marine gastropod.

    PubMed

    Ellingson, Ryan A; Krug, Patrick J

    2016-01-01

    Population-level consequences of dispersal ability remain poorly understood, especially for marine animals in which dispersal is typically considered a species-level trait governed by oceanographic transport of microscopic larvae. Transitions from dispersive (planktotrophic) to nondispersive, aplanktonic larvae are predicted to reduce connectivity, genetic diversity within populations, and the spatial scale at which reproductive isolation evolves. However, larval dimorphism within a species is rare, precluding population-level tests. We show the sea slug Costasiella ocellifera expresses both larval morphs in Florida and the Caribbean, regions with divergent mitochondrial lineages. Planktotrophy predominated at 11 sites, 10 of which formed a highly connected and genetically diverse Caribbean metapopulation. Four populations expressed mainly aplanktonic development and had markedly reduced connectivity, and lower genetic diversity at one mitochondrial and six nuclear loci. Aplanktonic dams showed partial postzygotic isolation in most interpopulation crosses, regardless of genetic or geographic distance to the sire's source, suggesting that outbreeding depression affects fragmented populations. Dams from genetically isolated and neighboring populations also exhibited premating isolation, consistent with reinforcement contingent on historical interaction. By increasing self-recruitment and genetic drift, the loss of dispersal may thus initiate a feedback loop resulting in the evolution of reproductive isolation over small spatial scales in the sea. PMID:26635309

  7. Larval dispersal and movement patterns of coral reef fishes, and implications for marine reserve network design.

    PubMed

    Green, Alison L; Maypa, Aileen P; Almany, Glenn R; Rhodes, Kevin L; Weeks, Rebecca; Abesamis, Rene A; Gleason, Mary G; Mumby, Peter J; White, Alan T

    2015-11-01

    Well-designed and effectively managed networks of marine reserves can be effective tools for both fisheries management and biodiversity conservation. Connectivity, the demographic linking of local populations through the dispersal of individuals as larvae, juveniles or adults, is a key ecological factor to consider in marine reserve design, since it has important implications for the persistence of metapopulations and their recovery from disturbance. For marine reserves to protect biodiversity and enhance populations of species in fished areas, they must be able to sustain focal species (particularly fishery species) within their boundaries, and be spaced such that they can function as mutually replenishing networks whilst providing recruitment subsidies to fished areas. Thus the configuration (size, spacing and location) of individual reserves within a network should be informed by larval dispersal and movement patterns of the species for which protection is required. In the past, empirical data regarding larval dispersal and movement patterns of adults and juveniles of many tropical marine species have been unavailable or inaccessible to practitioners responsible for marine reserve design. Recent empirical studies using new technologies have also provided fresh insights into movement patterns of many species and redefined our understanding of connectivity among populations through larval dispersal. Our review of movement patterns of 34 families (210 species) of coral reef fishes demonstrates that movement patterns (home ranges, ontogenetic shifts and spawning migrations) vary among and within species, and are influenced by a range of factors (e.g. size, sex, behaviour, density, habitat characteristics, season, tide and time of day). Some species move <0.1-0.5 km (e.g. damselfishes, butterflyfishes and angelfishes), <0.5-3 km (e.g. most parrotfishes, goatfishes and surgeonfishes) or 3-10 km (e.g. large parrotfishes and wrasses), while others move tens to hundreds

  8. Identifying appropriate spatial scales for marine conservation and management using a larval dispersal model: The case of Concholepas concholepas (loco) in Chile

    NASA Astrophysics Data System (ADS)

    Garavelli, Lysel; Kaplan, David Michael; Colas, François; Stotz, Wolfgang; Yannicelli, Beatriz; Lett, Christophe

    2014-05-01

    Along the coast of Chile, fisheries targeting the marine gastropod Concholepas concholepas, commonly named “loco”, were highly valuable until the end of the 80s when catches declined significantly. Since the late 90s, a management plan based on territorial-user-rights areas has been implemented, with limited effect on stock recovery. More effective loco conservation and management is impeded by lack of information regarding connectivity via larval dispersal between these individually-managed areas. To develop a regional view of loco connectivity, we integrate loco life history information into a biophysical, individual-based larval dispersal model. This model is used to evaluate scales of loco connectivity and seasonality in connectivity patterns, as well as to partition the coast into largely disconnected subpopulations using a recently developed connectivity-matrix clustering algorithm. We find mean dispersal distances ranging from 170 to 220 km depending on release depth of larvae and planktonic larval duration. Settlement success levels depend quantitatively on the physical and biological processes included in the model, but connectivity patterns remain qualitatively similar. Model estimates of settlement success peak for larval release dates in late austral autumn, consistent with field results and with favorable conditions for larval coastal retention due to weak upwelling during austral autumn. Despite the relatively homogeneous Chilean coastline, distinct subpopulations with minimal connectivity between them are readily identifiable. Barriers to connectivity that are robust to changes in model configuration exist at 23°S and 29°S latitudes. These zones are all associated with important headlands and embayments of the Chilean coast.

  9. A review of postfeeding larval dispersal in blowflies: implications for forensic entomology

    NASA Astrophysics Data System (ADS)

    Gomes, Leonardo; Godoy, Wesley Augusto Conde; von Zuben, Claudio José

    2006-05-01

    Immature and adult stages of blowflies are one of the primary invertebrate consumers of decomposing animal organic matter. When the food supply is consumed or when the larvae complete their development and migrate prior to the total removal of the larval substrate, they disperse to find adequate places for pupation, a process known as postfeeding larval dispersal. Several important ecological and physiological aspects of this process were studied since the work by Green (Ann Appl Biol 38:475, 1951) 50 years ago. An understanding of postfeeding larval dispersal can be useful for determining the postmortem interval (PMI) of human cadavers in legal medicine, particularly because this interval may be underestimated if older dispersing larvae or those that disperse longer, faster, and deeper are not taken into account. In this article, we review the process of postfeeding larval dispersal and its implications for legal medicine, in particular showing that aspects such as burial behavior and competition among species of blowflies can influence this process and consequently, the estimation of PMI.

  10. Asymmetric Dispersal Can Maintain Larval Polymorphism: A Model Motivated by Streblospio benedicti

    PubMed Central

    Zakas, Christina; Hall, David W.

    2012-01-01

    Polymorphism in traits affecting dispersal occurs in a diverse variety of taxa. Typically, the maintenance of a dispersal polymorphism is attributed to environmental heterogeneity where parental bet-hedging can be favored. There are, however, examples of dispersal polymorphisms that occur across similar environments. For example, the estuarine polychaete Streblospio benedicti has a highly heritable offspring dimorphism that affects larval dispersal potential. We use analytical models of dispersal to determine the conditions necessary for a stable dispersal polymorphism to exist. We show that in asexual haploids, sexual haploids, and in sexual diploids in the absence of overdominance, asymmetric dispersal is required in order to maintain a dispersal polymorphism when patches do not vary in intrinsic quality. Our study adds an additional factor, dispersal asymmetry, to the short list of mechanisms that can maintain polymorphism in nature. The region of the parameter space in which polymorphism is possible is limited, suggesting why dispersal polymorphisms within species are rare. PMID:22576818

  11. Numerical simulations of barnacle larval dispersion coupled with field observations on larval abundance, settlement and recruitment in a tropical monsoon influenced coastal marine environment

    NASA Astrophysics Data System (ADS)

    Gaonkar, Chetan A.; Samiksha, S. V.; George, Grinson; Aboobacker, V. M.; Vethamony, P.; Anil, Arga Chandrashekar

    2012-06-01

    Larval abundance in an area depends on various factors which operate over different spatial and temporal scales. Identifying the factors responsible for variations in larval supply and abundance is important to understand the settlement and recruitment variability of their population in a particular area. In view of this, observations were carried out to monitor the larval abundance, settlement and recruitment of barnacles on a regular basis for a period of two years. The results were then compared with the numerical modelling studies carried out along the west coast of India. Field observations of larval abundance showed temporal variations. The least abundance of larvae was mostly observed during the monsoon season and the peak in abundance was mostly observed during the pre-monsoon season. Numerical simulations also showed a seasonal change in larval dispersion and retention patterns. During pre-monsoon season the larval movement was mostly found towards south and the larvae released from the northern release sites contributed to larval abundance within the estuaries, whereas during the monsoon season the larval movement was mostly found towards north and the larvae released from southern release sites contributed to larval abundance within the estuary. During post-monsoon season, the larval movement was found towards the north in the beginning of the season and is shifted towards the south at the end of the season, but the movement was mostly restricted near to the release sites. Larval supply from the adjacent rocky sites to the estuaries was higher during the pre-monsoon season and the retention of larvae released from different sites within the estuaries was found to be highest during the late post-monsoon and early pre-monsoon season. Maximum larval supply and retention during the pre-monsoon season coincided with maximum larval abundance, settlement and recruitment of barnacles observed in the field studies. These observations showed that the pattern of

  12. Effect of Two Oil Dispersants on Larval Grass Shrimp (Palaemonetes pugio) Development.

    NASA Astrophysics Data System (ADS)

    Betancourt, P.; Key, P. B.; Chung, K. W.; DeLorenzo, M. E.

    2015-12-01

    The study focused on the effects that two oil dispersants, Corexit® EC9500A and Finasol® OSR52, have on the development of larval grass shrimp, (Palaemonetes pugio). The hypothesis was that Finasol would have a greater effect on larval grass shrimp development than Corexit. The experiment was conducted using 300 grass shrimp larvae that were 24 hours old. Each larva was exposed individually. In total, five sub-lethal concentrations were tested for each dispersant (control, 1.25, 2.50, 5.0,10.0 mg/L). The larvae were exposed for five days then transferred to clean seawater until metamorphosis into the juvenile stage. Key data measurements recorded included number of days to become juveniles, number of instars, length, dry weight, and mortality. Data from exposed shrimp was compared to the results of the control for each dispersant concentration. Corexit and Finasol exposure treatments of 5 mg/L and 10 mg/L showed significantly higher values for number of days and number of instars to reach juvenile status than values obtained from unexposed, control shrimp. Overall, mortality was higher in the Finasol treatments but the two dispersants did not respond significantly different from one another. Future studies are needed to determine the long term effects of dispersant exposure on all grass shrimp life stages and how any dispersant exposure impacts grass shrimp populations. Grass shrimp serve as excellent toxicity indicators of estuaries, and further studies will help to develop better oil spill mitigation techniques.

  13. Not my "type": larval dispersal dimorphisms and bet-hedging in opisthobranch life histories.

    PubMed

    Krug, Patrick J

    2009-06-01

    When conditions fluctuate unpredictably, selection may favor bet-hedging strategies that vary offspring characteristics to avoid reproductive wipe-outs in bad seasons. For many marine gastropods, the dispersal potential of offspring reflects both maternal effects (egg size, egg mass properties) and larval traits (development rate, habitat choice). I present data for eight sea slugs in the genus Elysia (Opisthobranchia: Sacoglossa), highlighting potentially adaptive variation in traits like offspring size, timing of metamorphosis, hatching behavior, and settlement response. Elysia zuleicae produced both planktotrophic and lecithotrophic larvae, a true case of poecilogony. Both intracapsular and post-hatching metamorphosis occurred among clutches of "Boselia" marcusi, E. cornigera, and E. crispata, a dispersal dimorphism often misinterpreted as poecilogony. Egg masses of E. tuca hatched for up to 16 days but larvae settled only on the adult host alga Halimeda, whereas most larvae of E. papillosa spontaneously metamorphosed 5-7 days after hatching. Investment in extra-capsular yolk may allow mothers to increase larval size relative to egg size and vary offspring size within and among clutches. Flexible strategies of larval dispersal and offspring provisioning in Elysia spp. may represent adaptations to the patchy habitat of these specialized herbivores, highlighting the evolutionary importance of variation in a range of life-history traits. PMID:19556600

  14. Modelling larval dispersal of the king scallop ( Pecten maximus) in the English Channel: examples from the bay of Saint-Brieuc and the bay of Seine

    NASA Astrophysics Data System (ADS)

    Nicolle, Amandine; Dumas, Franck; Foveau, Aurélie; Foucher, Eric; Thiébaut, Eric

    2013-06-01

    The king scallop ( Pecten maximus) is one of the most important benthic species of the English Channel as it constitutes the first fishery in terms of landings in this area. To support strategies of spatial fishery management, we develop a high-resolution biophysical model to study scallop dispersal in two bays along the French coasts of the English Channel (i.e. the bay of Saint-Brieuc and the bay of Seine) and to quantify the relative roles of local hydrodynamic processes, temperature-dependent planktonic larval duration (PLD) and active swimming behaviour (SB). The two bays are chosen for three reasons: (1) the distribution of the scallop stocks in these areas is well known from annual scallop stock surveys, (2) these two bays harbour important fisheries and (3) scallops in these two areas present some differences in terms of reproductive cycle and spawning duration. The English Channel currents and temperature are simulated for 10 years (2000-2010) with the MARS-3D code and then used by the Lagrangian module of MARS-3D to model the transport. Results were analysed in terms of larval distribution at settlement and connectivity rates. While larval transport in the two bays depended both on the tidal residual circulation and the wind-induced currents, the relative role of these two hydrodynamic processes varied among bays. In the bay of Saint-Brieuc, the main patterns of larval dispersal were due to tides, the wind being only a source of variability in the extent of larval patch and the local retention rate. Conversely, in the bay of Seine, wind-induced currents altered both the direction and the extent of larval transport. The main effect of a variable PLD in relation to the thermal history of each larva was to reduce the spread of dispersal and consequently increase the local retention by about 10 % on average. Although swimming behaviour could influence larval dispersal during the first days of the PLD when larvae are mainly located in surface waters, it has a

  15. Role of Upwelling on Larval Dispersal and Productivity of Gooseneck Barnacle Populations in the Cantabrian Sea: Management Implications

    PubMed Central

    Rivera, Antonella; Weidberg, Nicolás; Pardiñas, Antonio F.; González-Gil, Ricardo; García-Flórez, Lucía; Acuña, J. L.

    2013-01-01

    The effect of coastal upwelling on the recruitment and connectivity of coastal marine populations has rarely been characterized to a level of detail to be included into sound fishery management strategies. The gooseneck barnacle (Pollicipes pollicipes) fishery at the Cantabrian Coast (Northern Spain) is located at the fringes of the NW Spanish Upwelling system. This fishery is being co-managed through a fine-scale, interspersed set of protected rocks where each rock receives a distinct level of protection. Such interspersion is potentially beneficial, but the extent to which such spacing is consistent with mean larval dispersal distances is as yet unknown. We have simulated the spread of gooseneck barnacle larvae in the Central Cantabrian Coast using a high-resolution time-series of current profiles measured at a nearshore location. During a year of high upwelling activity (2009), theoretical recruitment success was 94% with peak recruitment predicted 56 km west of the emission point. However, for a year of low upwelling activity (2011) theoretical recruitment success dropped to 15.4% and peak recruitment was expected 13 km east of the emission point. This is consistent with a positive correlation between catch rates and the Integrated Upwelling Index, using a 4-year lag to allow recruits to reach commercial size. Furthermore, a net long-term westward larval transport was estimated by means of mitochondrial cytochrome c oxidase subunit I (COI) sequences for five populations in the Cantabrian Sea. Our results call into question the role of long distance dispersal, driven by the mesoscale processes in the area, in gooseneck barnacle populations and point to the prevalent role of small-scale, asymmetric connectivity more consistent with the typical scale of the co-management process in this fishery. PMID:24236020

  16. Stretched to the limit; can a short pelagic larval duration connect adult populations of an Indo-Pacific diadromous fish (Kuhlia rupestris)?

    PubMed

    Feutry, P; Vergnes, A; Broderick, D; Lambourdière, J; Keith, P; Ovenden, J R

    2013-03-01

    Freshwater species on tropical islands face localized extinction and the loss of genetic diversity. Their habitats can be ephemeral due to variability in freshwater run-off and erosion. Even worse, anthropogenic effects on these ecosystems are intense. Most of these species are amphidromous or catadromous (i.e. their life cycle includes a marine larval phase), which buffers them against many of these effects. A long pelagic larval duration (PLD) was thought to be critical to ensure the colonization and persistence in tropical islands, but recent findings indicated that several species with short PLDs are successful in those ecosystems. To test the potential of a short PLD in maintaining genetic connectivity and forestalling extirpation, we studied Kuhlia rupestris, a catadromous fish species with an extensive distribution in the western Pacific and Indian Oceans. Using a combination of molecular genetic markers (13 microsatellite loci and two gene regions from mtDNA) and modelling of larval dispersal, we show that a short PLD constrains genetic connectivity over a wide geographical range. Molecular markers showed that the short PLD did not prevent genetic divergence through evolutionary time and speciation has occurred or is occurring. Modelling of larvae dispersal suggested limited recent connectivity between genetically homogeneous populations across the Coral Sea. However, a short PLD can maintain connectivity on a subocean basin scale. Conservation and management of tropical diadromous species needs to take into account that population connectivity may be more limited than previously suspected in those species. PMID:23294379

  17. Dispersal of larval suckers at the Williamson River Delta, Upper Klamath Lake, Oregon, 2006-09

    USGS Publications Warehouse

    Wood, Tamara M.; Hendrixson, Heather A.; Markle, Douglas F.; Erdman, Charles S.; Burdick, Summer M.; Ellsworth, Craig M.; Buccola, Norman L.

    2012-01-01

    An advection/diffusion modeling approach was used to simulate the transport of larval suckers from spawning areas in the Williamson River, through the newly restored Williamson River Delta, to Upper Klamath Lake. The density simulations spanned the years of phased restoration, from 2006/2007 prior to any levee breaching, to 2008 when the northern part of the delta was reconnected to the lake, and 2009 when levees on both sides of the delta had been breached. Model simulation results from all four years were compared to field data using rank correlation. Spearman ρ correlation coefficients were usually significant and in the range 0.30 to 0.60, providing moderately strong validation of the model. The correlation coefficients varied with fish size class in a way that suggested that the model best described the distribution of smaller fish near the Williamson River channel, and larger fish away from the channel. When Lost River and shortnose/Klamath largescale suckers were simulated independently, the correlation results suggested that the model better described the transport and dispersal of the latter species. The incorporation of night-time-only drift behavior in the Williamson River channel neither improved nor degraded correlations with field data. The model showed that advection by currents is an important factor in larval dispersal.

  18. Connectivity and Dispersal Patterns of Protected Biogenic Reefs: Implications for the Conservation of Modiolus modiolus (L.) in the Irish Sea.

    PubMed

    Gormley, Kate; Mackenzie, Clara; Robins, Peter; Coscia, Ilaria; Cassidy, Andrew; James, Jenny; Hull, Angela; Piertney, Stuart; Sanderson, William; Porter, Joanne

    2015-01-01

    Biogenic reefs created by Modiolus modiolus (Linnaeus, 1758) (horse mussel reefs) are marine habitats which support high levels of species biodiversity and provide valuable ecosystem services. Currently, M. modiolus reefs are listed as a threatened and/or declining species and habitat in all OSPAR regions and thus are highlighted as a conservation priority under the EU Marine Strategy Framework Directive (MSFD). Determining patterns of larval dispersal and genetic connectivity of remaining horse mussel populations can inform management efforts and is a critical component of effective marine spatial planning (MSP). Larval dispersal patterns and genetic structure were determined for several M. modiolus bed populations in the Irish Sea including those in Wales (North Pen Llŷn), Isle of Man (Point of Ayre) and Northern Ireland (Ards Peninsula and Strangford Lough). Simulations of larval dispersal suggested extant connectivity between populations within the Irish Sea. Results from the genetic analysis carried out using newly developed microsatellite DNA markers were consistent with those of the biophysical model. Results indicated moderately significant differentiation between the Northern Ireland populations and those in the Isle of Man and Wales. Simulations of larval dispersal over a 30 day pelagic larval duration (PLD) suggest that connectivity over a spatial scale of 150km is possible between some source and sink populations. However, it appears unlikely that larvae from Northern Ireland will connect directly with sites on the Llŷn or Isle of Man. It also appears unlikely that larvae from the Llŷn connect directly to any of the other sites. Taken together the data establishes a baseline for underpinning management and conservation of these important and threatened marine habitats in the southern part of the known range. PMID:26625263

  19. Connectivity and Dispersal Patterns of Protected Biogenic Reefs: Implications for the Conservation of Modiolus modiolus (L.) in the Irish Sea

    PubMed Central

    Gormley, Kate; Mackenzie, Clara; Robins, Peter; Coscia, Ilaria; Cassidy, Andrew; James, Jenny; Hull, Angela; Piertney, Stuart; Sanderson, William; Porter, Joanne

    2015-01-01

    Biogenic reefs created by Modiolus modiolus (Linnaeus, 1758) (horse mussel reefs) are marine habitats which support high levels of species biodiversity and provide valuable ecosystem services. Currently, M. modiolus reefs are listed as a threatened and/or declining species and habitat in all OSPAR regions and thus are highlighted as a conservation priority under the EU Marine Strategy Framework Directive (MSFD). Determining patterns of larval dispersal and genetic connectivity of remaining horse mussel populations can inform management efforts and is a critical component of effective marine spatial planning (MSP). Larval dispersal patterns and genetic structure were determined for several M. modiolus bed populations in the Irish Sea including those in Wales (North Pen Llŷn), Isle of Man (Point of Ayre) and Northern Ireland (Ards Peninsula and Strangford Lough). Simulations of larval dispersal suggested extant connectivity between populations within the Irish Sea. Results from the genetic analysis carried out using newly developed microsatellite DNA markers were consistent with those of the biophysical model. Results indicated moderately significant differentiation between the Northern Ireland populations and those in the Isle of Man and Wales. Simulations of larval dispersal over a 30 day pelagic larval duration (PLD) suggest that connectivity over a spatial scale of 150km is possible between some source and sink populations. However, it appears unlikely that larvae from Northern Ireland will connect directly with sites on the Llŷn or Isle of Man. It also appears unlikely that larvae from the Llŷn connect directly to any of the other sites. Taken together the data establishes a baseline for underpinning management and conservation of these important and threatened marine habitats in the southern part of the known range. PMID:26625263

  20. Atlantic surfclam connectivity within the Middle Atlantic Bight: Mechanisms underlying variation in larval transport and settlement

    NASA Astrophysics Data System (ADS)

    Zhang, Xinzhong; Munroe, Daphne; Haidvogel, Dale; Powell, Eric N.

    2016-05-01

    Larval transport and settlement have been shown in various studies to be essential in determining population abundance and connectivity for benthic invertebrates. This transport is influenced by both the physical environment and biological behavior. The Atlantic surfclam, Spisula solidissima, is a commercially important benthic invertebrate fishery species along the U.S northeastern coast. In this study, a physical circulation model is coupled to a surfclam larval model to investigate the dynamics of larval transport and settlement within the Middle Atlantic Bight (MAB) shelf in 2006. The main physical mechanisms causing variability in larval transport and settlement are also examined. Model results show that surfclam larvae released from July to early October experience relatively larger settlement rates, due to higher average temperatures experienced by larvae. Larval along-shore transport exhibits a mean down-coast pattern following the coastal current from the northeast to the southwest, with most high-frequency (period of 2-10 days) variations caused by fluctuations in the along-shore surface wind stress, and with seasonal variations speculated to be driven mainly by changes in the across-shelf density gradient. Larval across-shelf movement is highly correlated with the along-shore surface wind stress mediated by coastal upwelling and downwelling episodes, but the correlation is further dependent on the vertical distribution of the larvae, particularly their position relative to the thermocline. Most surfclam larvae released from the Middle Atlantic shelf stay below the thermocline and experience a net onshore transport during the summer-stratified season when upwelling-favorable wind forcing dominates. A proposed critical value of water temperature at the thermocline successfully regulates the observed patterns of vertical distribution of surfclam larvae and their across-shelf movement off the New Jersey and South Virginia shelves; that is, when the water

  1. Connectivity patterns of coastal fishes following different dispersal scenarios across a transboundary marine protected area (Bonifacio strait, NW Mediterranean)

    NASA Astrophysics Data System (ADS)

    Koeck, Barbara; Gérigny, Olivia; Durieux, Eric Dominique Henri; Coudray, Sylvain; Garsi, Laure-Hélène; Bisgambiglia, Paul-Antoine; Galgani, François; Agostini, Sylvia

    2015-03-01

    The Strait of Bonifacio constitutes one of the rare transboundary Marine Protected Areas (MPA) of the Mediterranean Sea (between Sardinia, Italy and Corsica, France). Based on the hypothesis that no-take zones will produce more fish larvae, compared to adjacent fished areas, we modeled the outcome of larvae released by coastal fishes inside the no-take zones of the MPA in order to: (1) characterize the dispersal patterns across the Strait of Bonifacio; (2) identify the main potential settlement areas; (3) quantify the connectivity and the larval supply from the MPAs to the surrounding areas. A high resolution hydrodynamic model (MARS 3D, Corse 400 m) combined to an individual based model (Ichthyop software) was used to model the larval dispersal of fish following various scenarios (Pelagic Larval Duration PLD and release depth) over the main spawning period (i.e. between April and September). Dispersal model outputs were then compared with those obtained from an ichthyoplankton sampling cruise performed in August 2012. There was a significant influence of PLD to the connectivity between coastal areas. The synchronization between spawning and hydrodynamic conditions appeared to be determinant in the larval transport success. Biotic and abiotic parameters affecting the dispersal dynamic of fish larvae within the Strait of Bonifacio were identified and synthesis maps were established as a tool for conservation planning.

  2. A numerical study of marine larval dispersal in the presence of an axial convergent front

    NASA Astrophysics Data System (ADS)

    Robins, P. E.; Neill, S. P.; Giménez, L.

    2012-03-01

    Estuarine axial convergent fronts generate strong secondary (cross-estuary) flows which can be important for larval dispersal and settlement, and have been shown in this research to aid estuarine retention of natal populations which will promote production. This paper explores several larval migratory strategies, synchronised by sensory cues such as pressure, velocity, salinity and solar radiation, in relation to an estuarine axial convergent front - an important circulatory mechanism that forms in many coastal regions where larvae are concentrated; hence these results have implications for fisheries management. A three-dimensional hydrodynamic model is applied to an idealised channel, parameterised from observations of a well documented axial convergent front in the Conwy Estuary, UK. The model simulates the bilateral cross-sectional circulation of the front, attributed to the interaction of lateral shear of the longitudinal currents with the axial salinity gradient. Axial surface convergence develops during the flood phase of the tide and (weaker) surface divergence during the ebb phase. Lagrangian Particle Tracking Models subsequently use velocities from a range of simulated tidal and climatic scenarios to track larvae in the estuary. The results show that axial convergent fronts aid estuarine retention of larvae. Specifically retention is enhanced for larvae that experience tidal stream transport and diel migration. Tidally-synchronised larvae exhibit the strongest landward dispersal while the modelled copepod (a combination of tidal and salinity cues) exhibits 'full retention' in the mid-estuary release location. Finally, the vertical migration speed of the larvae must exceed the background vertical velocities in order to get the greatest enhancement of retention.

  3. Are genes faster than crabs? Mitochondrial introgression exceeds larval dispersal during population expansion of the invasive crab Carcinus maenas.

    PubMed

    Darling, John A; Tsai, Yi-Hsin Erica; Blakeslee, April M H; Roman, Joe

    2014-10-01

    Biological invasions offer unique opportunities to investigate evolutionary dynamics at the peripheries of expanding populations. Here, we examine genetic patterns associated with admixture between two distinct invasive lineages of the European green crab, Carcinus maenas L., independently introduced to the northwest Atlantic. Previous investigations based on mitochondrial DNA sequences demonstrated that larval dispersal driven by advective currents could explain observed southward displacement of an admixture zone between the two invasions. Comparison of published mitochondrial results with new nuclear data from nine microsatellite loci, however, reveals striking discordance in their introgression patterns. Specifically, introgression of mitochondrial genomes relative to nuclear background suggests that demographic processes such as sex-biased reproductive dynamics and population size imbalances-and not solely larval dispersal-play an important role in driving the evolution of the genetic cline. In particular, the unpredicted introgression of mitochondrial alleles against the direction of mean larval dispersal in the region is consistent with recent models invoking similar demographic processes to explain movements of genes into invading populations. These observations have important implications for understanding historical shifts in C. maenas range limits, and more generally for inferences of larval dispersal based on genetic data. PMID:26064543

  4. Connectivity from a different perspective: comparing seed dispersal kernels in connected vs. unfragmented landscapes.

    PubMed

    Herrmann, John D; Carlo, Tomas A; Brudvig, Lars A; Damschen, Ellen I; Haddad, Nick M; Levey, Douglas J; Orrock, John L; Tewksbury, Joshua J

    2016-05-01

    Habitat fragmentation can create significant impediments to dispersal. A technique to increase dispersal between otherwise isolated fragments is the use of corridors. Although previous studies have compared dispersal between connected fragments to dispersal between unconnected fragments, it remains unknown how dispersal between fragments connected by a corridor compares to dispersal in unfragmented landscapes. To assess the extent to which corridors can restore dispersal in fragmented landscapes to levels observed in unfragmented landscapes, we employed a stable-isotope marking technique to track seeds within four unfragmented landscapes and eight experimental landscapes with fragments connected by corridors. We studied two wind- and two bird-dispersed plant species, because previous community-based research showed that dispersal mode explains how connectivity effects vary among species. We constructed dispersal kernels for these species in unfragmented landscapes and connected fragments by marking seeds in the center of each landscape with 'IN and then recovering marked seeds in seed traps at distances up to 200 m. For the two wind-dispersed plants, seed dispersal kernels were similar in unfragmented landscapes and connected fragments. In contrast, dispersal kernels of bird-dispersed seeds were both affected by fragmentation and differed in the direction of the impact: Morella cerifera experienced more and Rhus copallina experienced less long-distance dispersal in unfragmented than in connected landscapes. These results show that corridors can facilitate dispersal probabilities comparable to those observed in unfragmented landscapes. Although dispersal mode may provide useful broad predictions, we acknowledge that similar species may respond uniquely due to factors such as seasonality and disperser behavior. Our results further indicate that prior work has likely underestimated dispersal distances of wind-dispersed plants and that factors altering long

  5. Sole larval supply to coastal nurseries: Interannual variability and connectivity at interregional and interpopulation scales

    NASA Astrophysics Data System (ADS)

    Savina, M.; Lunghi, M.; Archambault, B.; Baulier, L.; Huret, M.; Le Pape, O.

    2016-05-01

    Simulating fish larval drift helps assess the sensitivity of recruitment variability to early life history. An individual-based model (IBM) coupled to a hydrodynamic model was used to simulate common sole larval supply from spawning areas to coastal and estuarine nursery grounds at the meta-population scale (4 assessed stocks), from the southern North Sea to the Bay of Biscay (Western Europe) on a 26-yr time series, from 1982 to 2007. The IBM allowed each particle released to be transported by currents, to grow depending on temperature, to migrate vertically depending on development stage, to die along pelagic stages or to settle on a nursery, representing the life history from spawning to metamorphosis. The model outputs were analysed to explore interannual patterns in the amounts of settled sole larvae at the population scale; they suggested: (i) a low connectivity between populations at the larval stage, (ii) a moderate influence of interannual variation in the spawning biomass, (iii) dramatic consequences of life history on the abundance of settling larvae and (iv) the effects of climate variability on the interannual variability of the larvae settlement success.

  6. On the evolution of dispersal via heterogeneity in spatial connectivity

    PubMed Central

    Henriques-Silva, Renato; Boivin, Frédéric; Calcagno, Vincent; Urban, Mark C.; Peres-Neto, Pedro R.

    2015-01-01

    Dispersal has long been recognized as a mechanism that shapes many observed ecological and evolutionary processes. Thus, understanding the factors that promote its evolution remains a major goal in evolutionary ecology. Landscape connectivity may mediate the trade-off between the forces in favour of dispersal propensity (e.g. kin-competition, local extinction probability) and those against it (e.g. energetic or survival costs of dispersal). It remains, however, an open question how differing degrees of landscape connectivity may select for different dispersal strategies. We implemented an individual-based model to study the evolution of dispersal on landscapes that differed in the variance of connectivity across patches ranging from networks with all patches equally connected to highly heterogeneous networks. The parthenogenetic individuals dispersed based on a flexible logistic function of local abundance. Our results suggest, all else being equal, that landscapes differing in their connectivity patterns will select for different dispersal strategies and that these strategies confer a long-term fitness advantage to individuals at the regional scale. The strength of the selection will, however, vary across network types, being stronger on heterogeneous landscapes compared with the ones where all patches have equal connectivity. Our findings highlight how landscape connectivity can determine the evolution of dispersal strategies, which in turn affects how we think about important ecological dynamics such as metapopulation persistence and range expansion. PMID:25673685

  7. Are genes faster than crabs? Mitochondrial introgression exceeds larval dispersal during population expansion of the invasive crab Carcinus maenas

    PubMed Central

    Darling, John A.; Tsai, Yi-Hsin Erica; Blakeslee, April M. H.; Roman, Joe

    2014-01-01

    Biological invasions offer unique opportunities to investigate evolutionary dynamics at the peripheries of expanding populations. Here, we examine genetic patterns associated with admixture between two distinct invasive lineages of the European green crab, Carcinus maenas L., independently introduced to the northwest Atlantic. Previous investigations based on mitochondrial DNA sequences demonstrated that larval dispersal driven by advective currents could explain observed southward displacement of an admixture zone between the two invasions. Comparison of published mitochondrial results with new nuclear data from nine microsatellite loci, however, reveals striking discordance in their introgression patterns. Specifically, introgression of mitochondrial genomes relative to nuclear background suggests that demographic processes such as sex-biased reproductive dynamics and population size imbalances—and not solely larval dispersal—play an important role in driving the evolution of the genetic cline. In particular, the unpredicted introgression of mitochondrial alleles against the direction of mean larval dispersal in the region is consistent with recent models invoking similar demographic processes to explain movements of genes into invading populations. These observations have important implications for understanding historical shifts in C. maenas range limits, and more generally for inferences of larval dispersal based on genetic data. PMID:26064543

  8. Increasing the Depth of Current Understanding: Sensitivity Testing of Deep-Sea Larval Dispersal Models for Ecologists

    PubMed Central

    Nimmo-Smith, W. Alex M.; Howell, Kerry L.

    2016-01-01

    Larval dispersal is an important ecological process of great interest to conservation and the establishment of marine protected areas. Increasing numbers of studies are turning to biophysical models to simulate dispersal patterns, including in the deep-sea, but for many ecologists unassisted by a physical oceanographer, a model can present as a black box. Sensitivity testing offers a means to test the models’ abilities and limitations and is a starting point for all modelling efforts. The aim of this study is to illustrate a sensitivity testing process for the unassisted ecologist, through a deep-sea case study example, and demonstrate how sensitivity testing can be used to determine optimal model settings, assess model adequacy, and inform ecological interpretation of model outputs. Five input parameters are tested (timestep of particle simulator (TS), horizontal (HS) and vertical separation (VS) of release points, release frequency (RF), and temporal range (TR) of simulations) using a commonly employed pairing of models. The procedures used are relevant to all marine larval dispersal models. It is shown how the results of these tests can inform the future set up and interpretation of ecological studies in this area. For example, an optimal arrangement of release locations spanning a release area could be deduced; the increased depth range spanned in deep-sea studies may necessitate the stratification of dispersal simulations with different numbers of release locations at different depths; no fewer than 52 releases per year should be used unless biologically informed; three years of simulations chosen based on climatic extremes may provide results with 90% similarity to five years of simulation; and this model setup is not appropriate for simulating rare dispersal events. A step-by-step process, summarising advice on the sensitivity testing procedure, is provided to inform all future unassisted ecologists looking to run a larval dispersal simulation. PMID

  9. Increasing the Depth of Current Understanding: Sensitivity Testing of Deep-Sea Larval Dispersal Models for Ecologists.

    PubMed

    Ross, Rebecca E; Nimmo-Smith, W Alex M; Howell, Kerry L

    2016-01-01

    Larval dispersal is an important ecological process of great interest to conservation and the establishment of marine protected areas. Increasing numbers of studies are turning to biophysical models to simulate dispersal patterns, including in the deep-sea, but for many ecologists unassisted by a physical oceanographer, a model can present as a black box. Sensitivity testing offers a means to test the models' abilities and limitations and is a starting point for all modelling efforts. The aim of this study is to illustrate a sensitivity testing process for the unassisted ecologist, through a deep-sea case study example, and demonstrate how sensitivity testing can be used to determine optimal model settings, assess model adequacy, and inform ecological interpretation of model outputs. Five input parameters are tested (timestep of particle simulator (TS), horizontal (HS) and vertical separation (VS) of release points, release frequency (RF), and temporal range (TR) of simulations) using a commonly employed pairing of models. The procedures used are relevant to all marine larval dispersal models. It is shown how the results of these tests can inform the future set up and interpretation of ecological studies in this area. For example, an optimal arrangement of release locations spanning a release area could be deduced; the increased depth range spanned in deep-sea studies may necessitate the stratification of dispersal simulations with different numbers of release locations at different depths; no fewer than 52 releases per year should be used unless biologically informed; three years of simulations chosen based on climatic extremes may provide results with 90% similarity to five years of simulation; and this model setup is not appropriate for simulating rare dispersal events. A step-by-step process, summarising advice on the sensitivity testing procedure, is provided to inform all future unassisted ecologists looking to run a larval dispersal simulation. PMID:27575625

  10. Adult habitat preferences, larval dispersal, and the comparative phylogeography of three Atlantic surgeonfishes (Teleostei: Acanthuridae).

    PubMed

    Rocha, Luiz A; Bass, Anna L; Robertson, D Ross; Bowen, Brian W

    2002-02-01

    Although many reef fishes of the tropical Atlantic are widely distributed, there are large discontinuities that may strongly influence phylogeographical patterns. The freshwater outflow of the Amazon basin is recognized as a major barrier that produces a break between Brazilian and Caribbean faunas. The vast oceanic distances between Brazil and the mid-Atlantic ridge islands represent another formidable barrier. To assess the relative importance of these barriers, we compared a fragment of the mitochondrial DNA (mtDNA) cytochrome b gene among populations of three species of Atlantic surgeonfishes: Acanthurus bahianus, A. chirurgus and A. coeruleus. These species have similar life histories but different adult habitat preferences. The mtDNA data show no population structure between Brazil and the mid-Atlantic islands, indicating that this oceanic barrier is readily traversed by the pelagic larval stage of all three surgeonfishes, which spend approximately 45-70 days in the pelagic environment. The Amazon is a strong barrier to dispersal of A. bahianus (d = 0.024, phiST = 0.724), a modest barrier for A. coeruleus (phiST = 0.356), and has no discernible effect as a barrier for A. chirurgus. The later species has been collected on soft bottoms with sponge habitats under the Amazon outflow, indicating that relaxed adult habitat requirements enable it to readily cross that barrier. A limited ability to use soft bottom habitats may also explain the low (but significant) population structure in A. coeruleus. In contrast, A. bahianus has not been collected over deep sponge bottoms, and rarely settles outside shallow reefs. Overall, adult habitat preferences seem to be the factor that differentiates phylogeographical patterns in these reef-associated species. PMID:11856425

  11. Influence of flow regime and channel morphology on larval drift and dispersion in a large regulated river

    NASA Astrophysics Data System (ADS)

    Erwin, S.; Jacobson, R. B.

    2013-12-01

    Larval drift is a critical phase of ontogenetic development for many species of lotic fishes. Downstream advection and dispersion of passively drifting larvae or eggs is controlled by the complex interaction of flow regime, channel planform, local channel morphology, and the resulting hydraulic gradients. In many regulated rivers, channel engineering and perturbations to the flow regime may disrupt natural drift processes and impact successful recruitment of native fishes. Here we explore the influence of flow regime and channel morphology on the downstream transport, dispersion, and retention of Pallid Sturgeon larvae, an endangered species endemic to the Mississippi River basin and the focus of significant conservation effort on the Missouri River. The transition from drifting free embryo to exogenously feeding larvae has been identified as a potential life stage bottleneck for the Pallid Sturgeon. Previous studies have indicated that river regulation and fragmentation may contribute to mortality of larval Pallid Sturgeon by reducing the extent of free-flowing river required by free embryos to complete the transition to exogenous feeding. Additionally, channelization may have increased the rate at which larvae are advected downstream out of the Missouri River basin. We describe the complex interactions and influence of morphologic and hydraulic factors on larval drift using an extensive library of hydroacoustic data collected along more than 1300 km of the Lower Missouri River. We use a one-dimensional advection-dispersion model to estimate total drift distance and employ the longitudinal dispersion coefficient as a measure to quantify the tendency towards dispersion or retention of passively drifting larvae in geomorphically distinct segments of river. We use a two-dimensional hydrodynamic model to evaluate the sensitivity of drift and dispersion to in-channel navigation structures and flood hydrology. Based on insights gained from the analysis of field data and

  12. Dispersal of stable flies (Diptera: Muscidae) from larval development sites in a Nebraska landscape

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seven mark recapture studies of stable flies wer conducted in a mixed agricultural environment in northeastern Nebraska. Larval developmental sites were marked by dusting the surface with fluorescent pigments and stable flies were recaptured with grids of Alsynite sticky traps. Recaptured flies were...

  13. Evidence of the St. Clair-Detroit River system as a dispersal corridor and nursery habitat for transient larval burbot

    USGS Publications Warehouse

    McCullough, Darrin E.; Roseman, Edward F.; Keeler, Kevin M.; DeBruyne, Robin L.; Pritt, Jeremy J.; Thompson, Patricia A.; Ireland, Stacey A.; Ross, Jason E.; Bowser, Dustin; Hunter, Robert D.; Castle, Dana Kristina; Fischer, Jason; Provo, Stacy A.

    2015-01-01

    Burbot Lota lota are distributed across the Laurentian Great Lakes where they occupy a top piscivore role. The St. Clair-Detroit River System is known to provide a migration corridor as well as spawning and nursery habitat for many indigenous fishes of economic and ecological significance. However, knowledge is scant of the early life history of burbot and the importance of this system in their dispersal, survival, and recruitment. In order to assess the role of the St. Clair-Detroit River System to burbot ecology, we collected larval burbot during ichthyoplankton surveys in this system from 2010 to 2013 as part of a habitat restoration monitoring program. More and larger burbot larvae were found in the St. Clair River than in the lower Detroit River, although this may be due to differences in sampling methods between the two rivers. Consistent with existing studies, larval burbot exhibited ontogenesis with a distinct transition from a pelagic zooplankton-based diet to a benthic macroinvertebrate-based diet. Our results demonstrate that the St. Clair-Detroit Rivers provide food resources, required habitat, and a migration conduit between the upper and lower Great Lakes, but the contribution of these fish to the lower lakes requires further examination.

  14. Fisheries Closed Areas Strengthen Scallop Larval Settlement and Connectivity Among Closed Areas and Across International Open Fishing Grounds: A Model Study

    NASA Astrophysics Data System (ADS)

    Davies, Kimberley T. A.; Gentleman, W. C.; DiBacco, C.; Johnson, C. L.

    2015-09-01

    This study examined whether a measured increase in average body size of adult sea scallops inside three fishery closed areas on Georges Bank (GB), United States (US), was sufficient to increase larval supply to closed areas and open fishing areas in both US and Canadian areas of the Bank. The effects of adult scallop density-at-size and fecundity-at-size on egg production were compared among open and closed fishery areas, countries, and time periods before and after the closed areas were established. Estimated egg production was then used to define spawning conditions in a coupled biological-physical larval tracking model that simulated larval development, mortality, and dispersal. Results showed that order of magnitude increases in larval settlement after closure were facilitated by increases in size-dependant egg production inside and dispersal from Closed Areas I and II, but not Nantucket Lightship Closed Area. The distributions of both egg production and larval settlement became more uniform across the Bank, causing the relative contribution of Canadian larvae to US scallop aggregations to decrease after establishment of Closed Areas I and II. Decreases in small and medium-sized scallop density in Canada and decreases in large scallops over the US-Southern Flank after closure caused local declines in egg production but were not sufficient to negatively affect larval settlement at the regional scale. Our model suggests that the establishment of fishery closed areas on GB considerably strengthened larval supply and settlement within and among several adult scallop aggregations.

  15. Postfeeding larval dispersal behavior of late season blow flies (calliphoridae) in Southern Ontario, Canada.

    PubMed

    Turpin, Chantal; Kyle, Christopher; Beresford, David V

    2014-09-01

    Postfeeding dispersal involves migration of larvae away from their food source in order to pupate. Puparia are difficult to find, yet are important for estimating PMI, and missing puparia during collection can result in inaccurate estimations. This study investigates the late season maggot dispersal patterns for blow flies at coyote carcasses in two habitats with an aim to improving puparia collection procedures. Puparia samples collected from various dispersal distances and directions tested the spatial distribution patterns of the various species using the variance/mean ratio (VMR). Lucilia illustris was the most common species to emerge, with a preferred minimum dispersal distance of more than 50.8 cm and an overall VMR value of 14.91, indicating this species had a clumped distribution pattern. These findings highlight that current collection procedures that use random sampling from under carcasses do not adequately account for the spatial distribution of larvae. PMID:24602116

  16. Evaluation of a Stable Isotope Method to Mark Naturally-Breeding Larval Mosquitoes for Adult Dispersal Studies

    PubMed Central

    HAMER, GABRIEL L.; DONOVAN, DANIELLE J.; HOOD-NOWOTNY, REBECCA; KAUFMAN, MICHAEL G.; GOLDBERG, TONY L.; WALKER, EDWARD D.

    2014-01-01

    Understanding mosquito dispersal is critically important for vector-borne disease control and prevention. Mark–release–recapture methods using various marking techniques have made substantial contributions to the study of mosquito biology. However, the ability to mark naturally breeding mosquitoes noninvasively and with life-long retention has remained problematic. Here, we describe a method to mark naturally breeding mosquitoes with stable isotopes. Culexpipiens f. molestus mosquitoes were provisioned as larvae in laboratory experiments with 15N-labeled potassium nitrate and 13C-labeled glucose. Larval enrichment was sufficient to differentiate marked adult mosquitoes from unmarked control mosquitoes and the natural source population from Chicago Illinois, using either δ15N or δ13C. Isotopic retention lasted for at least 55 d for adult male and females mosquitoes. There were no consistent effects of isotopic enrichment on immature mosquito survival or adult mosquito body size. We then applied this marking technique to naturally breeding Culex pipiens mosquitoes in suburban Chicago, IL, and for the first time, report successful isotopic enrichment of mosquitoes in the field. This stable isotope marking technique will facilitate studies of mosquito dispersal. PMID:22308772

  17. Dispersal of post-larval macrobenthos in subtidal sedimentary habitats: Roles of vertical diel migration, water column, bedload transport and biological traits' expression

    NASA Astrophysics Data System (ADS)

    Pacheco, Aldo S.; Uribe, Roberto A.; Thiel, Martin; Oliva, Marcelo E.; Riascos, Jose M.

    2013-03-01

    Post-larval dispersal along the sediment-water interface is an important process in the dynamics of macrobenthic populations and communities in marine sublittoral sediments. However, the modes of post-larval dispersal in low energy sublittoral habitats have been poorly documented. Herein we examined the specific dispersal mechanisms (diel vertical migration, water column, and bedload transport) and corresponding biological traits of the dispersing assemblage. At two sublittoral sites (sheltered and exposed) along the northern coast of Chile, we installed different trap types that capture benthic organisms with specific modes of dispersal (active emergence and passive water column drifting) and also by a combination of mechanisms (bedload transport, passive suspension and settlement from the water column). Our results show that even though there were common species in all types of traps, the post-larval macrobenthic assemblage depended on specific mechanisms of dispersal. At the sheltered site, abundant emerging taxa colonized sediments that were placed 0.5 m above the bottom and bedload-transported invertebrates appeared to be associated to the passive drifting of macroalgae. At the exposed site, assemblage dispersal was driven by specific mechanisms e.g. bedload transport and active emergence. At both sites the biological traits "small size, swimming, hard exoskeleton, free living and surface position" were associated to water column and bedload dispersal. This study highlights the importance of (i) the water-sediment interface for dispersal of post-larvae in sublittoral soft-bottom habitat, and (ii) a specific set of biological traits when dispersing either along the bottom or through the water column.

  18. Larval dispersal of the weed biological control agent Oxyops vitiosa (Coleoptera: Curculionidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Australian weevil Oxyops vitiosa is a biological control agent of the exotic tree Melaleuca quinquenervia in Florida, USA. Evidence suggests that the last instar drops from the canopy to the forest floor to pupate in the soil or leaf litter. This dispersal method preempts weevil population persi...

  19. Oceanographic and behavioural processes affecting invertebrate larval dispersal and supply in the western Iberia upwelling ecosystem

    NASA Astrophysics Data System (ADS)

    Queiroga, Henrique; Cruz, Teresa; dos Santos, Antonina; Dubert, Jesus; González-Gordillo, Juan Ignácio; Paula, José; Peliz, Álvaro; Santos, A. Miguel P.

    2007-08-01

    The present review addresses recent findings made in the western Iberia ecosystem on the behavioural and physical interactions that regulate dispersal, supply to coastal habitats and settlement of invertebrate larvae. These studies used the barnacle Chthamalus spp. and the crab Carcinus maenas as model organisms. The observations made on the Iberian shelf showed extensive diel vertical migrations along the water column by representatives of both groups that have never been reported before. The interaction of the diel vertical migration with the two-layer flow structure of upwelling/downwelling circulation suggests a mechanism that may help to retain larvae in shelf waters during upwelling conditions. Measurements of daily supply of C. maenas megalopae to estuaries separated by 500 km disclosed a semilunar pattern, with highest supply around highest amplitude tides, indicating that supply of megalopae to estuaries is accomplished by selective tidal stream transport. Relaxation of equatorward winds also played a role in supply, by enhancing translocation of megalopae to the nearshore. Concerning Chthamalus larvae, the observations on daily settlement made at rocky shores also separated by 500 km showed unclear patterns between locations and years. The relationship of settlement with water temperature, tidal range and upwelling indices indicated that supply of barnacle cyprids may be controlled by multiple mechanisms, viz. upwelling/downwelling circulation, internal tidal bores and sea breezes.

  20. Simulation and validation of larval sucker dispersal and retention through the restored Williamson River Delta and Upper Klamath Lake system, Oregon

    USGS Publications Warehouse

    Wood, Tamara M.; Hendrixson, Heather A.; Markle, Douglas F.; Erdman, Charles S.; Burdick, Summer M.; Ellsworth, Craig M.

    2014-01-01

    A hydrodynamic model with particle tracking was used to create individual-based simulations to describe larval fish dispersal through the restored Williamson River Delta and into Upper Klamath Lake, Oregon. The model was verified by converting particle ages to larval lengths and comparing these lengths to lengths of larvae in net catches. Correlations of simulated lengths with field data were moderate and suggested a species-specific difference in model performance. Particle trajectories through the delta were affected by wind speed and direction, lake elevation, and shoreline configuration. Once particles entered the lake, transport was a function of current speed and whether behavior enhanced transport (swimming aligned with currents) or countered transport through greater dispersal (faster random swimming). We tested sensitivity to swim speed (higher speeds led to greater dispersal and more retention), shoreline configuration (restoration increased retention relative to pre-restoration conditions), and lake elevation (retention was maximized at an intermediate elevation). The simulations also highlight additional biological questions, such as the extent to which spatially heterogeneous mortality or fish behavior and environmental cues could interact with wind-driven currents and contribute to patterns of dispersal.

  1. The influence of spawning periodicity on population connectivity

    NASA Astrophysics Data System (ADS)

    Kough, Andrew S.; Paris, Claire B.

    2015-09-01

    Many coral reef populations exist as discrete habitat patches linked through larval dispersal into a larger network. On these reefs, organisms spawn periodically and release propagules over a range of frequencies. Biophysical models of larval transport examine marine networks, yet particle release frequency needs careful consideration. We describe the time between sequential spawning events as the release interval and define any linkage of modeled larvae between two habitat sites as a connection. We investigate how changing the release interval affects the connectivity networks of three Caribbean species with low- to high-dispersal potential and swimming behavior. We find that spawning periodicity controls the number and persistence of network connections. Further, larval vertical movement behavior stabilizes the network, significantly increasing connections and connection persistence. This work demonstrates the impact of release interval on connectivity networks and underscores including larval behavior with realistic spawning periodicity in biophysical models of larval transport.

  2. Across-Shelf Transport of Bivalve Larvae: Can the Interface between a Coastal Current and Inshore Waters Act as an Ecological Barrier to Larval Dispersal?

    PubMed Central

    Tilburg, Charles E.; McCartney, Michael A.; Yund, Philip O.

    2012-01-01

    Using an integrated physical and biological approach, we examined across-shelf advection and exchange and the associated transport of bivalve larvae in the presence of a strong coastal current separated from the coast by a stratified inshore environment. We tested the hypothesis that the interface of the coastal current and inshore waters can act as an ecological barrier to across-shelf transport of larvae but can be overcome by wind- or tidally-induced transport. Our study region in the Gulf of Maine encompasses a coastal current that diverges from the coast as it moves downshelf. The region inshore of this current is home to several species that exhibit limited recruitment in spite of extensive upshelf larval sources. Analysis of surface water temperatures and wind velocities revealed episodic decreases in temperature along the coast correlated with alongshelf (but not upwelling) winds, indicating wind-forced onshore movement of the cold coastal current. Such wind-driven onshore migrations are more common along the northern portion of the study region where the coastal current is near the coast, tidal currents are strong, and wind directions are more conducive to onshore migration, but rarer further south where the interface between inshore waters and the coastal current is further offshore and suitable wind events are less common. The distribution of bivalve larvae was consistent with the physical measurements. There was little across-shelf variation in larval abundance where the current abuts the coast, indicating strong across-shelf exchange of larvae, but strong across-shelf variation in larval density where the stratified inshore waters separate the current from the coast, indicating weak across-shelf transport of larvae. Our results suggest that the interface between the coastal current and inshore waters may constitute a major ecological barrier to larval dispersal in the southern part of the region that may only be overcome by rare, strong wind

  3. Dispersal of Adult Culex Mosquitoes in an Urban West Nile Virus Hotspot: A Mark-Capture Study Incorporating Stable Isotope Enrichment of Natural Larval Habitats

    PubMed Central

    Hamer, Gabriel L.; Anderson, Tavis K.; Donovan, Danielle J.; Brawn, Jeffrey D.; Krebs, Bethany L.; Gardner, Allison M.; Ruiz, Marilyn O.; Brown, William M.; Kitron, Uriel D.; Newman, Christina M.; Goldberg, Tony L.; Walker, Edward D.

    2014-01-01

    Dispersal is a critical life history behavior for mosquitoes and is important for the spread of mosquito-borne disease. We implemented the first stable isotope mark-capture study to measure mosquito dispersal, focusing on Culex pipiens in southwest suburban Chicago, Illinois, a hotspot of West Nile virus (WNV) transmission. We enriched nine catch basins in 2010 and 2011 with 15N-potassium nitrate and detected dispersal of enriched adult females emerging from these catch basins using CDC light and gravid traps to distances as far as 3 km. We detected 12 isotopically enriched pools of mosquitoes out of 2,442 tested during the two years and calculated a mean dispersal distance of 1.15 km and maximum flight range of 2.48 km. According to a logistic distribution function, 90% of the female Culex mosquitoes stayed within 3 km of their larval habitat, which corresponds with the distance-limited genetic variation of WNV observed in this study region. This study provides new insights on the dispersal of the most important vector of WNV in the eastern United States and demonstrates the utility of stable isotope enrichment for studying the biology of mosquitoes in other disease systems. PMID:24676212

  4. Long-Distance Dispersal via Ocean Currents Connects Omani Clownfish Populations throughout Entire Species Range

    PubMed Central

    Claereboudt, Michel R.; Planes, Serge

    2014-01-01

    Dispersal is a crucial ecological process, driving population dynamics and defining the structure and persistence of populations. Measuring demographic connectivity between discreet populations remains a long-standing challenge for most marine organisms because it involves tracking the movement of pelagic larvae. Recent studies demonstrate local connectivity of reef fish populations via the dispersal of planktonic larvae, while biogeography indicates some larvae must disperse 100–1000 s kilometres. To date, empirical measures of long-distance dispersal are lacking and the full scale of dispersal is unknown. Here we provide the first measure of long-distance dispersal in a coral reef fish, the Omani clownfish Amphiprion omanensis, throughout its entire species range. Using genetic assignment tests we demonstrate bidirectional exchange of first generation migrants, with subsequent social and reproductive integration, between two populations separated by over 400 km. Immigration was 5.4% and 0.7% in each region, suggesting a biased southward exchange, and matched predictions from a physically-coupled dispersal model. This rare opportunity to measure long-distance dispersal demonstrates connectivity of isolated marine populations over distances of 100 s of kilometres and provides a unique insight into the processes of biogeography, speciation and adaptation. PMID:25229550

  5. Passive advection-dispersion in networks of pipes: Effect of connectivity and relationship to permeability

    NASA Astrophysics Data System (ADS)

    Bernabé, Y.; Wang, Y.; Qi, T.; Li, M.

    2016-02-01

    The main purpose of this work is to investigate the relationship between passive advection-dispersion and permeability in porous materials presumed to be statistically homogeneous at scales larger than the pore scale but smaller than the reservoir scale. We simulated fluid flow through pipe network realizations with different pipe radius distributions and different levels of connectivity. The flow simulations used periodic boundary conditions, allowing monitoring of the advective motion of solute particles in a large periodic array of identical network realizations. In order to simulate dispersion, we assumed that the solute particles obeyed Taylor dispersion in individual pipes. When a particle entered a pipe, a residence time consistent with local Taylor dispersion was randomly assigned to it. When exiting the pipe, the particle randomly proceeded into one of the pipes connected to the original one according to probabilities proportional to the outgoing volumetric flow in each pipe. For each simulation we tracked the motion of at least 6000 solute particles. The mean fluid velocity was 10-3 ms-1, and the distance traveled was on the order of 10 m. Macroscopic dispersion was quantified using the method of moments. Despite differences arising from using different types of lattices (simple cubic, body-centered cubic, and face-centered cubic), a number of general observations were made. Longitudinal dispersion was at least 1 order of magnitude greater than transverse dispersion, and both strongly increased with decreasing pore connectivity and/or pore size variability. In conditions of variable hydraulic radius and fixed pore connectivity and pore size variability, the simulated dispersivities increased as power laws of the hydraulic radius and, consequently, of permeability, in agreement with previously published experimental results. Based on these observations, we were able to resolve some of the complexity of the relationship between dispersivity and permeability.

  6. Marine population connectivity: reconciling large-scale dispersal and high self-retention.

    PubMed

    Nickols, Kerry J; White, J Wilson; Largier, John L; Gaylord, Brian

    2015-02-01

    Predicting connectivity patterns in systems with fluid transport requires descriptions of the spatial distribution of propagules. In contrast to research on terrestrial seed dispersal, where much attention has focused on localized physical factors affecting dispersal, studies of oceanic propagule dispersal have often emphasized the role of large-scale factors. We link these two perspectives by exploring how propagule dispersal in the ocean is influenced by the "coastal boundary layer" (CBL), a region of reduced velocities near the shoreline that might substantially modify local-scale dispersal. We used a simple simulation model to demonstrate that accounting for the CBL markedly alters transport distances, the widths of dispersal distributions, and the fraction of larvae retained near their sites of origin (self-retention). Median dispersal distances were up to 59% shorter in simulations with a CBL than in those without. Self-retention of larvae increased by up to 3 orders of magnitude in the presence of CBLs, but only minor changes arose in the long-distance tails of the distributions, resulting in asymmetric, non-Gaussian kernels analogous to those quantified for terrestrial seed dispersal. Because successfully settling larvae are commonly those that remain close to shore and interact with the CBL, ignoring this pervasive oceanographic feature will substantially alter predictions of population self-persistence, estimates of connectivity, and outcomes of metapopulation analyses. PMID:25616139

  7. How Nemo finds home: the neuroecology of dispersal and of population connectivity in larvae of marine fishes.

    PubMed

    Leis, Jeffrey M; Siebeck, Ulrike; Dixson, Danielle L

    2011-11-01

    Nearly all demersal teleost marine fishes have pelagic larval stages lasting from several days to several weeks, during which time they are subject to dispersal. Fish larvae have considerable swimming abilities, and swim in an oriented manner in the sea. Thus, they can influence their dispersal and thereby, the connectivity of their populations. However, the sensory cues marine fish larvae use for orientation in the pelagic environment remain unclear. We review current understanding of these cues and how sensory abilities of larvae develop and are used to achieve orientation with particular emphasis on coral-reef fishes. The use of sound is best understood; it travels well underwater with little attenuation, and is current-independent but location-dependent, so species that primarily utilize sound for orientation will have location-dependent orientation. Larvae of many species and families can hear over a range of ~100-1000 Hz, and can distinguish among sounds. They can localize sources of sounds, but the means by which they do so is unclear. Larvae can hear during much of their pelagic larval phase, and ontogenetically, hearing sensitivity, and frequency range improve dramatically. Species differ in sensitivity to sound and in the rate of improvement in hearing during ontogeny. Due to large differences among-species within families, no significant differences in hearing sensitivity among families have been identified. Thus, distances over which larvae can detect a given sound vary among species and greatly increase ontogenetically. Olfactory cues are current-dependent and location-dependent, so species that primarily utilize olfactory cues will have location-dependent orientation, but must be able to swim upstream to locate sources of odor. Larvae can detect odors (e.g., predators, conspecifics), during most of their pelagic phase, and at least on small scales, can localize sources of odors in shallow water, although whether they can do this in pelagic

  8. Does stability in local community composition depend on temporal variation in rates of dispersal and connectivity?

    NASA Astrophysics Data System (ADS)

    Valanko, Sebastian; Norkko, Joanna; Norkko, Alf

    2015-04-01

    In ecology understanding variation in connectivity is central for how biodiversity is maintained. Field studies on dispersal and temporal dynamics in community regulating processes are, however, rare. We test the short-term temporal stability in community composition in a soft-sediment benthic community by determining among-sampling interval similarity in community composition. We relate stability to in situ measures of connectivity (wind, wave, current energy) and rates of dispersal (quantified in different trap types). Waves were an important predictor of when local community taxa are most likely to disperse in different trap-types, suggesting that wave energy is important for connectivity in a region. Community composition at the site was variable and changed stochastically over time. We found changes in community composition (occurrence, abundance, dominance) to be greater at times when connectivity and rates of dispersal were low. In response to periods of lower connectedness dominant taxa in the local community only exhibited change in their relative abundance. In contrast, locally less abundant taxa varied in both their presence, as well as in relative abundance. Constancy in connectivity and rates of dispersal promotes community stability and persistence, suggesting that local community composition will be impacted by changes in the spatial extent over which immigration and emigration operates in the region. Few empirical studies have actually measured dispersal directly in a multi-species context to demonstrate the role it plays in maintaining local community structure. Even though our study does not evaluate coexistence over demographic time scales, it importantly demonstrates that dispersal is not only important in initial recruitment or following a disturbance, but also key in maintaining local community composition.

  9. Influence of Biological Factors on Connectivity Patterns for Concholepas concholepas (loco) in Chile

    PubMed Central

    Garavelli, Lysel; Colas, François; Verley, Philippe; Kaplan, David Michael; Yannicelli, Beatriz; Lett, Christophe

    2016-01-01

    In marine benthic ecosystems, larval connectivity is a major process influencing the maintenance and distribution of invertebrate populations. Larval connectivity is a complex process to study as it is determined by several interacting factors. Here we use an individual-based, biophysical model, to disentangle the effects of such factors, namely larval vertical migration, larval growth, larval mortality, adults fecundity, and habitat availability, for the marine gastropod Concholepas concholepas (loco) in Chile. Lower transport success and higher dispersal distances are observed including larval vertical migration in the model. We find an overall decrease in larval transport success to settlement areas from northern to southern Chile. This spatial gradient results from the combination of current direction and intensity, seawater temperature, and available habitat. From our simulated connectivity patterns we then identify subpopulations of loco along the Chilean coast, which could serve as a basis for spatial management of this resource in the future. PMID:26751574

  10. Influence of Biological Factors on Connectivity Patterns for Concholepas concholepas (loco) in Chile.

    PubMed

    Garavelli, Lysel; Colas, François; Verley, Philippe; Kaplan, David Michael; Yannicelli, Beatriz; Lett, Christophe

    2016-01-01

    In marine benthic ecosystems, larval connectivity is a major process influencing the maintenance and distribution of invertebrate populations. Larval connectivity is a complex process to study as it is determined by several interacting factors. Here we use an individual-based, biophysical model, to disentangle the effects of such factors, namely larval vertical migration, larval growth, larval mortality, adults fecundity, and habitat availability, for the marine gastropod Concholepas concholepas (loco) in Chile. Lower transport success and higher dispersal distances are observed including larval vertical migration in the model. We find an overall decrease in larval transport success to settlement areas from northern to southern Chile. This spatial gradient results from the combination of current direction and intensity, seawater temperature, and available habitat. From our simulated connectivity patterns we then identify subpopulations of loco along the Chilean coast, which could serve as a basis for spatial management of this resource in the future. PMID:26751574

  11. 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.

  12. Genetic evidence supports larval retention in the Western Caribbean for an invertebrate with high dispersal capability ( Ophiothrix suensonii: Echinodermata, Ophiuroidea)

    NASA Astrophysics Data System (ADS)

    Richards, V. P.; DeBiasse, M. B.; Shivji, M. S.

    2015-03-01

    The brittle star Ophiothrix suensonii is a common coral reef sponge commensal with high dispersal potential. Here, we utilize COI sequence data from 264 O. suensonii individuals collected from 10 locations throughout Florida and the Caribbean to investigate dispersal dynamics and demographic history. Locations separated by up to 1,700 km lacked genetic differentiation, confirming the ability for long-range dispersal. However, significant differentiation was detected among other regions. Samples from Utila, Honduras showed the greatest differentiation, suggesting that the circulation of the Mesoamerican gyre could be a significant factor restricting gene flow in this region. Demographic analyses provided strong evidence for a population expansion, possibly out of Florida, through the Caribbean, and into Honduras, which commenced in the early Pleistocene. However, the presence of a clade of rare haplotypes, which split much earlier (mid-Pliocene), indicates that O. suensonii persisted long before its recent expansion, suggesting a cyclic history of population contraction and expansion. Finally, patterns of gene flow are not concordant with contemporary surface currents; rather, they reflect historical movements possibly linked with changes in circulation during periods of Pleistocene climate change.

  13. Influence of the larval phase on connectivity: strong differences in the genetic structure of brooders and broadcasters in the Ophioderma longicauda species complex.

    PubMed

    Weber, A A-T; Mérigot, B; Valière, S; Chenuil, A

    2015-12-01

    Closely related species with divergent life history traits are excellent models to infer the role of such traits in genetic diversity and connectivity. Ophioderma longicauda is a brittle star species complex composed of different genetic clusters, including brooders and broadcasters. These species diverged very recently and some of them are sympatric and ecologically syntopic, making them particularly suitable to study the consequences of their trait differences. At the scale of the geographic distribution of the broadcasters (Mediterranean Sea and northeastern Atlantic), we sequenced the mitochondrial marker COI and genotyped an intron (i51) for 788 individuals. In addition, we sequenced 10 nuclear loci newly developed from transcriptome sequences, for six sympatric populations of brooders and broadcasters from Greece. At the large scale, we found a high genetic structure within the brooders (COI: 0.07 < F(ST) < 0.65) and no polymorphism at the nuclear locus i51. In contrast, the broadcasters displayed lower genetic structure (0 < F(ST) < 0.14) and were polymorphic at locus i51. At the regional scale, the multilocus analysis confirmed the contrasting genetic structure between species, with no structure in the broadcasters (global F(ST) < 0.001) and strong structure in the brooders (global F(ST) = 0.49), and revealed a higher genetic diversity in broadcasters. Our study showed that the lecithotrophic larval stage allows on average a 50-fold increase in migration rates, a 280-fold increase in effective size and a threefold to fourfold increase in genetic diversity. Our work, investigating complementary genetic markers on sympatric and syntopic taxa, highlights the strong impact of the larval phase on connectivity and genetic diversity. PMID:26547515

  14. Hydration State and Aqueous Phase Connectivity Shape Microbial Dispersal Rates in Unsaturated Angular Pore Networks

    NASA Astrophysics Data System (ADS)

    Or, D.; Ebrahimi, A.

    2014-12-01

    The limited dispersal of self-propelled microorganisms and constrained nutrient transport in unsaturated soils are considered key factors in the promotion and maintenance of soil microbial diversity. Despite the importance of microbial dispersal to biogeochemical and ecological functioning of soil, little is known about how pore spaces and hydration conditions affect dispersal ranges and rates of motile bacteria. To address these questions quantitatively, we developed a novel 3-D pore network model (PNM) composed of triangular bonds connected to cubic (volumeless) bonds to mimic the salient geometrical and physical properties of natural pore spaces. Within this abstracted physical domain we employed individual based models for motile microorganisms that are capable of motion, nutrient consumption, growth and cell division. We focused on dispersal rates through the network as a function of hydration conditions through its impact on aqueous phase fragmentation that suppress nutrient diffusion (hence growth rates) and dispersal rates in good agreement with limited experimental data. Chemotactically-biased mean travel rates of microbial cells across the saturated PNM was ~3 mm/hr and decreased exponentially to 0.45 mm/hr for matric potential of (at dispersal practically ceases and cells are pinned by capillary forces). Individual-based results were upscaled to describe population scale dispersal rates, and PNM predictions considering different microbial cell sizes were in good agreement with experimental results for unsaturated soils. The role of convection for most unsaturated conditions was negligible relative to self-motility highlighting the need to constrain continuum models with respect to cell size and motility to imporve predictions of transport of motile microorganisms. The modeling platform confirms universal predictions based on percolation theory for the onset of aqueous phase fragmentation that limit dispersal and provide niches essential for species

  15. Directed dispersal by rotational shepherding supports landscape genetic connectivity in a calcareous grassland plant.

    PubMed

    Rico, Yessica; Holderegger, Rolf; Boehmer, Hans Juergen; Wagner, Helene H

    2014-02-01

    Directed dispersal by animal vectors has been found to have large effects on the structure and dynamics of plant populations adapted to frugivory. Yet, empirical data are lacking on the potential of directed dispersal by rotational grazing of domestic animals to mediate gene flow across the landscape. Here, we investigated the potential effect of large-flock shepherding on landscape-scale genetic structure in the calcareous grassland plant Dianthus carthusianorum, whose seeds lack morphological adaptations to dispersal to animals or wind. We found a significant pattern of genetic structure differentiating population within grazed patches of three nonoverlapping shepherding systems and populations of ungrazed patches. Among ungrazed patches, we found a strong and significant effect of isolation by distance (r = 0.56). In contrast, genetic distance between grazed patches within the same herding system was unrelated to geographical distance but significantly related to distance along shepherding routes (r = 0.44). This latter effect of connectivity along shepherding routes suggests that gene flow is spatially restricted occurring mostly between adjacent populations. While this study used nuclear markers that integrate gene flow by pollen and seed, the significant difference in the genetic structure between ungrazed patches and patches connected by large-flock shepherding indicates the potential of directed seed dispersal by sheep across the landscape. PMID:24451046

  16. Disjunct distribution of highly diverged mitochondrial lineage clade and population subdivision in a marine bivalve with pelagic larval dispersal.

    PubMed

    Luttikhuizen, P C; Drent, J; Baker, A J

    2003-08-01

    are currently isolated, while others appear to be connected by gene flow. Apparently, populations of this species can remain highly subdivided in spite of the potential for high gene flow, implying that their population and evolutionary dynamics can be independent. PMID:12859640

  17. Long Distance Dispersal and Connectivity in Amphi-Atlantic Corals at Regional and Basin Scales

    PubMed Central

    Nunes, Flavia L. D.; Norris, Richard D.; Knowlton, Nancy

    2011-01-01

    Among Atlantic scleractinian corals, species diversity is highest in the Caribbean, but low diversity and high endemism are observed in various peripheral populations in central and eastern Atlantic islands and along the coasts of Brazil and West Africa. The degree of connectivity between these distantly separated populations is of interest because it provides insight into processes at both evolutionary and ecological time scales, such as speciation, recruitment dynamics and the persistence of coral populations. To assess connectivity in broadly distributed coral species of the Atlantic, DNA sequence data from two nuclear markers were obtained for six coral species spanning their distributional ranges. At basin-wide scales, significant differentiation was generally observed among populations in the Caribbean, Brazil and West Africa. Concordance of patterns in connectivity among co-distributed taxa indicates that extrinsic barriers, such as the Amazon freshwater plume or long stretches of open ocean, restrict dispersal of coral larvae from region to region. Within regions, dispersal ability appears to be influenced by aspects of reproduction and life history. Two broadcasting species, Siderastrea siderea and Montastraea cavernosa, were able to maintain gene flow among populations separated by as much as 1,200 km along the coast of Brazil. In contrast, brooding species, such as Favia gravida and Siderastrea radians, had more restricted gene flow along the Brazilian coast. PMID:21799816

  18. Drosophila adult and larval pheromones modulate larval food choice

    PubMed Central

    Farine, Jean-Pierre; Cortot, Jérôme; Ferveur, Jean-François

    2014-01-01

    Insects use chemosensory cues to feed and mate. In Drosophila, the effect of pheromones has been extensively investigated in adults, but rarely in larvae. The colonization of natural food sources by Drosophila buzzatii and Drosophila simulans species may depend on species-specific chemical cues left in the food by larvae and adults. We identified such chemicals in both species and measured their influence on larval food preference and puparation behaviour. We also tested compounds that varied between these species: (i) two larval volatile compounds: hydroxy-3-butanone-2 and phenol (predominant in D. simulans and D. buzzatii, respectively), and (ii) adult cuticular hydrocarbons (CHs). Drosophila buzzatii larvae were rapidly attracted to non-CH adult conspecific cues, whereas D. simulans larvae were strongly repulsed by CHs of the two species and also by phenol. Larval cues from both species generally reduced larval attraction and pupariation on food, which was generally—but not always—low, and rarely reflected larval response. As these larval and adult pheromones specifically influence larval food search and the choice of a pupariation site, they may greatly affect the dispersion and survival of Drosophila species in nature. PMID:24741012

  19. Experimental evaluation of connectivity influence on dispersivity under confined and unconfined radial convergent flow conditions

    NASA Astrophysics Data System (ADS)

    Guzzi, Silvia; Molinari, Antonio; Fallico, Carmine; Pedretti, Daniele

    2014-05-01

    Heterogeneity and connectivity have a significant impact on the fate and transport of contaminants due to the occurrence of formations with largest permeability than the surrounding geological materials, which can originate preferential pathways in groundwater system. These issues are usually addressed by tracer tests and a radial convergent (RC) flow setting is typically selected for convenience but more complicated for model interpretation than uniform flow transport. An experimental investigation was performed using RC tracer tests in a 3D intermediate scale physical model to illustrate the role of connected features on the estimation of dispersivity using the classical Sauty solution and the method of moments, under confined and unconfined aquifer conditions. The physical model consists of 26 piezometers located at difference distances from a constant-discharge central pumping well. The box is filled with gravel channels embedded in a sandy matrix and organized in different layers. Materials have been well characterized before and after the test. For the confined configuration, a silt layer was placed above the previous layers. Tracer tests were performed using potassium iodide solutions with concentration of 3•10-3 M and under a constant pumping flow rate of 0.05 L/s. To mimic a pulse injection in each piezometer we used syringes and pipes, whereas a probe allowed continuous measuring of tracer concentration. Average velocity and longitudinal dispersion coefficient were defined from the first and second central moment of the observed breakthrough curves for each piezometer (integrated over the outflow boundary of the domain) and using the classical curve matching from the Sauty's solution at different Péclet numbers. Results reveal in some cases that estimates of hydrodynamic parameters from the Sauty solution and the method of moments seem to be different. This is related to the different basic assumptions of the two methods applied, and especially because

  20. Effects on electrical distribution networks of dispersed power generation at high levels of connection penetration

    SciTech Connect

    Longrigg, P

    1983-07-01

    The advent and deployment of significant levels of photovoltaic and wind energy generation in the spatially dispersed mode (i.e., residential and intermediate load centers) may have deleterious effects upon existing protective relay equipment and its time-current coordination on radial distribution circuits to which power conditioning equipment may be connected for power sell-back purposes. The problems that may arise involve harmonic injection from power conditioning inverters that can affect protective relays and cause excessive voltage and current from induced series and parallel resonances on feeders and connected passive equipment. Voltage regulation, var requirements, and consumer metering can also be affected by this type of dispersed generation. The creation of islands of supply is also possible, particularly on rural supply systems. This paper deals mainly with the effects of harmonics and short-circuit currents from wind energy conversion systems (WECS) and photovoltaic (PV) systems upon the operating characteristics of distribution networks and relays and other protective equipment designed to ensure the safety and supply integrity of electrical utility networks. Traditionally, electrical supply networks have been designed for one-way power flow-from generation to load, with a balance maintained between the two by means of automatic generation and load-frequency controls. Dispersed generation, from renewables like WECS or PV or from nonrenewable resources, can change traditional power flow. These changes must be dealt with effectively if renewable energy resources are to be integrated into the utility distribution system. This paper gives insight into these problems and proposes some solutions.

  1. Dispersal

    USGS Publications Warehouse

    2001-01-01

    The ability of species to migrate and disperse is a trait that has interested ecologists for many years. Now that so many species and ecosystems face major environmental threats from habitat fragmentation and global climate change, the ability of species to adapt to these changes by dispersing, migrating, or moving between patches of habitat can be crucial to ensuring their survival. This book provides a timely and wide-ranging overview of the study of dispersal and incorporates much of the latest research. The causes, mechanisms, and consequences of dispersal at the individual, population, species and community levels are considered. The potential of new techniques and models for studying dispersal, drawn from molecular biology and demography, is also explored. Perspectives and insights are offered from the fields of evolution, conservation biology and genetics. Throughout the book, theoretical approaches are combined with empirical data, and care has been taken to include examples from as wide a range of species as possible.

  2. 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

  3. Embryogenesis and larval biology of the cold-water coral Lophelia pertusa.

    PubMed

    Larsson, Ann I; Järnegren, Johanna; 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

  4. Detecting larval export from marine reserves

    PubMed Central

    Pelc, R. A.; Warner, R. R.; Gaines, S. D.; Paris, C. B.

    2010-01-01

    Marine reserve theory suggests that where large, productive populations are protected within no-take marine reserves, fished areas outside reserves will benefit through the spillover of larvae produced in the reserves. However, empirical evidence for larval export has been sparse. Here we use a simple idealized coastline model to estimate the expected magnitude and spatial scale of larval export from no-take marine reserves across a range of reserve sizes and larval dispersal scales. Results suggest that, given the magnitude of increased production typically found in marine reserves, benefits from larval export are nearly always large enough to offset increased mortality outside marine reserves due to displaced fishing effort. However, the proportional increase in recruitment at sites outside reserves is typically small, particularly for species with long-distance (on the order of hundreds of kilometers) larval dispersal distances, making it very difficult to detect in field studies. Enhanced recruitment due to export may be detected by sampling several sites at an appropriate range of distances from reserves or at sites downcurrent of reserves in systems with directional dispersal. A review of existing empirical evidence confirms the model's suggestion that detecting export may be difficult without an exceptionally large differential in production, short-distance larval dispersal relative to reserve size, directional dispersal, or a sampling scheme that encompasses a broad range of distances from the reserves. PMID:20181570

  5. Genes and song: genetic and social connections in fragmented habitat in a woodland bird with limited dispersal.

    PubMed

    Pavlova, Alexandra; Amos, J Nevil; Goretskaia, Maria I; Beme, Irina R; Buchanan, Katherine L; Takeuchi, Naoko; Radford, James Q; Sunnucks, Paul

    2012-07-01

    Understanding the processes leading to population declines in fragmented landscapes is essential for successful conservation management. However, isolating the influence of disparate processes, and dispersal in particular, is challenging. The Grey Shrike-thrush, Colluricincla harmonica, is a sedentary woodland-dependent songbird, with learned vocalizations whose incidence in suitable habitat patches falls disproportionally with decline in tree cover in the landscape. Although it has been suggested that gaps in tree cover might act as barriers to its dispersal, the species remains in many remnants of native vegetation in agricultural landscapes, suggesting that it may have responded to habitat removal and fragmentation by maintaining or even increasing dispersal distances. We quantified population connectivity of the Grey Shrike-thrush in a system fragmented over more than 120 years using genetic (microsatellites) and acoustic (song types) data. First, we tested for population genetic and acoustic structure at regional and local scales in search of barriers to dispersal or gene flow and signals of local spatial structuring indicative of restricted dispersal or localized acoustic similarity. Then we tested for effects of habitat loss and fragmentation on genetic and acoustic connectivity by fitting alternative models of mobility (isolation-by-distance [the null model] and reduced and increased movement models) across treeless vs. treed areas. Birds within -5 km of each other had more similar genotypes and song types than those farther away, suggesting that dispersal and song matching are limited in the region. Despite restricted dispersal detected for females (but not males), populations appeared to be connected by gene flow and displayed some cultural (acoustic) connectivity across the region. Fragmentation did not appear to impact greatly the dispersal of the Grey Shrike-thrush: none of the mobility models fit the genetic distances of males, whereas for females, an

  6. Population Connectivity Shifts at High Frequency within an Open-Coast Marine Protected Area Network

    PubMed Central

    Cook, Geoffrey S.; Parnell, P. Ed; Levin, Lisa A.

    2014-01-01

    A complete understanding of population connectivity via larval dispersal is of great value to the effective design and management of marine protected areas (MPA). However empirical estimates of larval dispersal distance, self-recruitment, and within season variability of population connectivity patterns and their influence on metapopulation structure remain rare. We used high-resolution otolith microchemistry data from the temperate reef fish Hypsypops rubicundus to explore biweekly, seasonal, and annual connectivity patterns in an open-coast MPA network. The three MPAs, spanning 46 km along the southern California coastline were connected by larval dispersal, but the magnitude and direction of connections reversed between 2008 and 2009. Self-recruitment, i.e. spawning, dispersal, and settlement to the same location, was observed at two locations, one of which is a MPA. Self-recruitment to this MPA ranged from 50–84%; within the entire 60 km study region, self-recruitment accounted for 45% of all individuals settling to study reefs. On biweekly time scales we observed directional variability in alongshore current data and larval dispersal trajectories; if viewed in isolation these data suggest the system behaves as a source-sink metapopulation. However aggregate biweekly data over two years reveal a reef network in which H. rubicundus behaves more like a well-mixed metapopulation. As one of the few empirical studies of population connectivity within a temperate open coast reef network, this work can inform the MPA design process, implementation of ecosystem based management plans, and facilitate conservation decisions. PMID:25077486

  7. Okeanos Explorer 2014 Gulf of Mexico Expedition: engaging and connecting with diverse and geographically dispersed audiences

    NASA Astrophysics Data System (ADS)

    Russell, C. W.; Elliott, K.; Lobecker, E.; McKenna, L.; Haynes, S.; Crum, E.; Gorell, F.

    2014-12-01

    From February to May 2014, NOAA Ship Okeanos Explorer conducted a telepresence-enabled ocean exploration expedition addressing NOAA and National deepwater priorities in the U.S. Gulf of Mexico. The community-driven expedition connected diverse and geographically dispersed audiences including scientists from industry, academia, and government, and educators, students, and the general public. Expedition planning included input from the ocean science and management community, and was executed with more than 70 scientists and students from 14 U.S. states participating from shore in real time. Training the next generation permeated operations: a mapping internship program trained undergraduate and graduate students; an ROV mentorship program trained young engineers to design, build and operate the system; and undergraduate through doctoral students around the country collaborated with expedition scientists via telepresence. Online coverage of the expedition included background materials, daily updates, and mission logs that received more than 100,000 visits by the public. Live video feeds of operations received more than 700,000 views online. Additionally, professional development workshops hosted in multiple locations throughout the spring introduced educators to the Okeanos Explorer Educational Materials Collection and the live expedition, and taught them how to use the website and education resources in their classrooms. Social media furthered the reach of the expedition to new audiences, garnered thousands of new followers and provided another medium for real-time interactions with the general public. Outreach continued through live interactions with museums and aquariums, Exploration Command Center tours, outreach conducted by partners, and media coverage in more than 190 outlets in the U.S. and Europe. Ship tours were conducted when the ship came in to port to engage local scientists, ocean managers, and educators. After the expedition, data and products were

  8. Morphology of First Zoeal Stage of Four Genera of Alvinocaridid Shrimps from Hydrothermal Vents and Cold Seeps: Implications for Ecology, Larval Biology and Phylogeny

    PubMed Central

    Hernández-Ávila, Iván; Cambon-Bonavita, Marie-Anne; Pradillon, Florence

    2015-01-01

    Alvinocaridid shrimps are endemic species inhabiting hydrothermal vents and/or cold seeps. Although indirect evidences (genetic and lipid markers) suggest that their larval stages disperse widely and support large scale connectivity, larval life and mechanisms underlying dispersal are unknown in alvinocaridids. Here we provide for the first time detailed descriptions of the first larval stage (zoea I) of four alvinocaridid species: Rimicaris exoculata and Mirocaris fortunata from the Mid-Atlantic Ridge, Alvinocaris muricola from the Congo Basin and Nautilocaris saintlaurentae from the Western Pacific. The larvae were obtained from onboard hatching of brooding females (either at atmospheric pressure or at habitat pressure in hyperbaric chambers) and from the water column near adult habitats, sampled with plankton pumps or sediment traps. Major characteristics of the alvinocaridid larvae include undeveloped mandible and almost complete absence of setation in the inner margin of the mouth parts and maxillipeds. Although the larvae are very similar between the four species studied, some morphological features could be used for species identification. In addition, undeveloped mouthparts and the large amount of lipid reserves strongly support the occurrence of primary lecithotrophy in the early stage of alvinocaridids. Although lecithotrophy in decapod crustaceans is usually associated with abbreviated larval development, as a mechanism of larval retention, morphological and physiological evidences suggest the occurrence of an extended and lecithotrophic larval stage in the Alvinocarididae. These traits permit the colonization of widely dispersed and fragmented environments of hydrothermal vents and cold seeps. Distribution of larval traits along the phylogenetic reconstruction of the Alvinocarididae and related families suggest that lecithotrophy/planktotrophy and extended/abbreviated development have evolved independently along related families in all potential

  9. Morphology of First Zoeal Stage of Four Genera of Alvinocaridid Shrimps from Hydrothermal Vents and Cold Seeps: Implications for Ecology, Larval Biology and Phylogeny.

    PubMed

    Hernández-Ávila, Iván; Cambon-Bonavita, Marie-Anne; Pradillon, Florence

    2015-01-01

    Alvinocaridid shrimps are endemic species inhabiting hydrothermal vents and/or cold seeps. Although indirect evidences (genetic and lipid markers) suggest that their larval stages disperse widely and support large scale connectivity, larval life and mechanisms underlying dispersal are unknown in alvinocaridids. Here we provide for the first time detailed descriptions of the first larval stage (zoea I) of four alvinocaridid species: Rimicaris exoculata and Mirocaris fortunata from the Mid-Atlantic Ridge, Alvinocaris muricola from the Congo Basin and Nautilocaris saintlaurentae from the Western Pacific. The larvae were obtained from onboard hatching of brooding females (either at atmospheric pressure or at habitat pressure in hyperbaric chambers) and from the water column near adult habitats, sampled with plankton pumps or sediment traps. Major characteristics of the alvinocaridid larvae include undeveloped mandible and almost complete absence of setation in the inner margin of the mouth parts and maxillipeds. Although the larvae are very similar between the four species studied, some morphological features could be used for species identification. In addition, undeveloped mouthparts and the large amount of lipid reserves strongly support the occurrence of primary lecithotrophy in the early stage of alvinocaridids. Although lecithotrophy in decapod crustaceans is usually associated with abbreviated larval development, as a mechanism of larval retention, morphological and physiological evidences suggest the occurrence of an extended and lecithotrophic larval stage in the Alvinocarididae. These traits permit the colonization of widely dispersed and fragmented environments of hydrothermal vents and cold seeps. Distribution of larval traits along the phylogenetic reconstruction of the Alvinocarididae and related families suggest that lecithotrophy/planktotrophy and extended/abbreviated development have evolved independently along related families in all potential

  10. Hydrodynamic provinces and oceanic connectivity from a transport network help designing marine reserves

    NASA Astrophysics Data System (ADS)

    Rossi, Vincent; Ser-Giacomi, Enrico; López, Cristóbal; Hernández-García, Emilio

    2014-04-01

    Oceanic dispersal and connectivity have been identified as crucial factors for structuring marine populations and designing marine protected areas (MPAs). Focusing on larval dispersal by ocean currents, we propose an approach coupling Lagrangian transport and new tools from Network Theory to characterize marine connectivity in the Mediterranean basin. Larvae of different pelagic durations and seasons are modeled as passive tracers advected in a simulated oceanic surface flow from which a network of connected areas is constructed. Hydrodynamical provinces extracted from this network are delimited by frontiers which match multiscale oceanographic features. By examining the repeated occurrence of such boundaries, we identify the spatial scales and geographic structures that would control larval dispersal across the entire seascape. Based on these hydrodynamical units, we study novel connectivity metrics for existing reserves. Our results are discussed in the context of ocean biogeography and MPAs design, having ecological and managerial implications.

  11. MODELING SCALE-DEPENDENT LANDSCAPE PATTERN, DISPERSAL, AND CONNECTIVITY FROM THE PERSPECTIVE OF THE ORGANISM

    EPA Science Inventory

    Effects of fine- to broad-scale patterns of landscape heterogeneity on dispersal success were examined for organisms varying in life history traits. To systematically control spatial pattern, a landscape model was created by merging physiographically-based maps of simulated land...

  12. 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

  13. Exploration of the "larval pool": development and ground-truthing of a larval transport model off leeward Hawai'i.

    PubMed

    Wren, Johanna L K; Kobayashi, Donald R

    2016-01-01

    Most adult reef fish show site fidelity thus dispersal is limited to the mobile larval stage of the fish, and effective management of such species requires an understanding of the patterns of larval dispersal. In this study, we assess larval reef fish distributions in the waters west of the Big Island of Hawai'i using both in situ and model data. Catches from Cobb midwater trawls off west Hawai'i show that reef fish larvae are most numerous in offshore waters deeper than 3,000 m and consist largely of pre-settlement Pomacanthids, Acanthurids and Chaetodontids. Utilizing a Lagrangian larval dispersal model, we were able to replicate the observed shore fish distributions from the trawl data and we identified the 100 m depth strata as the most likely depth of occupancy. Additionally, our model showed that for larval shore fish with a pelagic larval duration longer than 40 days there was no significant change in settlement success in our model. By creating a general additive model (GAM) incorporating lunar phase and angle we were able to explain 67.5% of the variance between modeled and in situ Acanthurid abundances. We took steps towards creating a predictive larval distribution model that will greatly aid in understanding the spatiotemporal nature of the larval pool in west Hawai'i, and the dispersal of larvae throughout the Hawaiian archipelago. PMID:26855873

  14. Quantifying dispersal from hydrothermal vent fields in the western Pacific Ocean

    PubMed Central

    Mitarai, Satoshi; Watanabe, Hiromi; Nakajima, Yuichi; Shchepetkin, Alexander F.; McWilliams, James C.

    2016-01-01

    Hydrothermal vent fields in the western Pacific Ocean are mostly distributed along spreading centers in submarine basins behind convergent plate boundaries. Larval dispersal resulting from deep-ocean circulations is one of the major factors influencing gene flow, diversity, and distributions of vent animals. By combining a biophysical model and deep-profiling float experiments, we quantify potential larval dispersal of vent species via ocean circulation in the western Pacific Ocean. We demonstrate that vent fields within back-arc basins could be well connected without particular directionality, whereas basin-to-basin dispersal is expected to occur infrequently, once in tens to hundreds of thousands of years, with clear dispersal barriers and directionality associated with ocean currents. The southwest Pacific vent complex, spanning more than 4,000 km, may be connected by the South Equatorial Current for species with a longer-than-average larval development time. Depending on larval dispersal depth, a strong western boundary current, the Kuroshio Current, could bridge vent fields from the Okinawa Trough to the Izu-Bonin Arc, which are 1,200 km apart. Outcomes of this study should help marine ecologists estimate gene flow among vent populations and design optimal marine conservation plans to protect one of the most unusual ecosystems on Earth. PMID:26929376

  15. Quantifying dispersal from hydrothermal vent fields in the western Pacific Ocean.

    PubMed

    Mitarai, Satoshi; Watanabe, Hiromi; Nakajima, Yuichi; Shchepetkin, Alexander F; McWilliams, James C

    2016-03-15

    Hydrothermal vent fields in the western Pacific Ocean are mostly distributed along spreading centers in submarine basins behind convergent plate boundaries. Larval dispersal resulting from deep-ocean circulations is one of the major factors influencing gene flow, diversity, and distributions of vent animals. By combining a biophysical model and deep-profiling float experiments, we quantify potential larval dispersal of vent species via ocean circulation in the western Pacific Ocean. We demonstrate that vent fields within back-arc basins could be well connected without particular directionality, whereas basin-to-basin dispersal is expected to occur infrequently, once in tens to hundreds of thousands of years, with clear dispersal barriers and directionality associated with ocean currents. The southwest Pacific vent complex, spanning more than 4,000 km, may be connected by the South Equatorial Current for species with a longer-than-average larval development time. Depending on larval dispersal depth, a strong western boundary current, the Kuroshio Current, could bridge vent fields from the Okinawa Trough to the Izu-Bonin Arc, which are 1,200 km apart. Outcomes of this study should help marine ecologists estimate gene flow among vent populations and design optimal marine conservation plans to protect one of the most unusual ecosystems on Earth. PMID:26929376

  16. High connectivity across the fragmented chemosynthetic ecosystems of the deep Atlantic Equatorial Belt: efficient dispersal mechanisms or questionable endemism?

    PubMed

    Teixeira, Sara; Olu, Karine; Decker, Carole; Cunha, Regina L; Fuchs, Sandra; Hourdez, Stéphane; Serrão, Ester A; Arnaud-Haond, Sophie

    2013-09-01

    Chemosynthetic ecosystems are distributed worldwide in fragmented habitats harbouring seemingly highly specialized communities. Yet, shared taxa have been reported from highly distant chemosynthetic communities. These habitats are distributed in distinct biogeographical regions, one of these being the so-called Atlantic Equatorial Belt (AEB). Here, we combined genetic data (COI) from several taxa to assess the possible existence of cryptic or synonymous species and to detect the possible occurrence of contemporary gene flow among populations of chemosynthetic species located on both sides of the Atlantic. Several Evolutionary Significant Units (ESUs) of Alvinocarididae shrimp and Vesicomyidae bivalves were found to be shared across seeps of the AEB. Some were also common to hydrothermal vent communities of the Mid-Atlantic Ridge (MAR), encompassing taxa morphologically described as distinct species or even genera. The hypothesis of current or very recent large-scale gene flow among seeps and vents was supported by microsatellite analysis of the shrimp species Alvinocaris muricola/Alvinocaris markensis across the AEB and MAR. Two nonmutually exclusive hypotheses may explain these findings. The dispersion of larvae or adults following strong deep-sea currents, possibly combined with biochemical cues influencing the duration of larval development and timing of metamorphosis, may result in large-scale effective migration among distant spots scattered on the oceanic seafloor. Alternatively, these results may arise from the prevailing lack of knowledge on the ocean seabed, apart from emblematic ecosystems (chemosynthetic ecosystems, coral reefs or seamounts), where the widespread classification of endemism associated with many chemosynthetic taxa might hide wider distributions in overlooked parts of the deep sea. PMID:23927457

  17. Examination of circulation, dispersion, and connectivity in Lunenburg Bay of Nova Scotia using a nested-grid circulation model

    NASA Astrophysics Data System (ADS)

    Sheng, Jinyu; Zhao, Jun; Zhai, Li

    2009-05-01

    A coastal ocean observatory has been established in Lunenburg Bay, Nova Scotia since summer 2002 as part of a multi-agency research program of marine environmental observation and prediction over Atlantic Canada coastal waters. The observatory was operational when a category-2 hurricane (Juan) made land fall within 50-km of the bay in September 2003. The coastal response of the bay to Hurricane Juan is examined using a nested-grid coastal circulation modelling system. The nested-grid system is forced by the local wind, tides, and remotely generated coastal waves. A comparison of model results with observed surface elevations and currents demonstrates that the nested-grid system has reasonable skills in simulating the three-dimensional (3D) storm-induced circulation in the study region. The 3D model currents are used to examine the transport and dispersion of passive tracers, local flushing time, and retention and connectivity of passive particles in the bay during Hurricane Juan. Numerical results demonstrate that local wind forcing plays a dominant role in generating large dispersion and hydrodynamic connectivity in the bay during the storm.

  18. Drosophila Homolog of Human KIF22 at the Autism-Linked 16p11.2 Loci Influences Synaptic Connectivity at Larval Neuromuscular Junctions.

    PubMed

    Park, Sang Mee; Littleton, J Troy; Park, Hae Ryoun; Lee, Ji Hye

    2016-02-01

    Copy number variations at multiple chromosomal loci, including 16p11.2, have recently been implicated in the pathogenesis of autism spectrum disorder (ASD), a neurodevelopmental disease that affects 1~3% of children worldwide. The aim of this study was to investigate the roles of human genes at the 16p11.2 loci in synaptic development using Drosophila larval neuromuscular junctions (NMJ), a well-established model synapse with stereotypic innervation patterns. We conducted a preliminary genetic screen based on RNA interference in combination with the GAL4-UAS system, followed by mutational analyses. Our result indicated that disruption of klp68D, a gene closely related to human KIF22, caused ectopic innervations of axon branches forming type III boutons in muscle 13, along with less frequent re-routing of other axon branches. In addition, mutations in klp64D, of which gene product forms Kinesin-2 complex with KLP68D, led to similar targeting errors of type III axons. Mutant phenotypes were at least partially reproduced by knockdown of each gene via RNA interference. Taken together, our data suggest the roles of Kinesin-2 proteins, including KLP68D and KLP64D, in ensuring proper synaptic wiring. PMID:26924931

  19. Drosophila Homolog of Human KIF22 at the Autism-Linked 16p11.2 Loci Influences Synaptic Connectivity at Larval Neuromuscular Junctions

    PubMed Central

    Park, Sang Mee; Littleton, J. Troy; Park, Hae Ryoun

    2016-01-01

    Copy number variations at multiple chromosomal loci, including 16p11.2, have recently been implicated in the pathogenesis of autism spectrum disorder (ASD), a neurodevelopmental disease that affects 1~3% of children worldwide. The aim of this study was to investigate the roles of human genes at the 16p11.2 loci in synaptic development using Drosophila larval neuromuscular junctions (NMJ), a well-established model synapse with stereotypic innervation patterns. We conducted a preliminary genetic screen based on RNA interference in combination with the GAL4-UAS system, followed by mutational analyses. Our result indicated that disruption of klp68D, a gene closely related to human KIF22, caused ectopic innervations of axon branches forming type III boutons in muscle 13, along with less frequent re-routing of other axon branches. In addition, mutations in klp64D, of which gene product forms Kinesin-2 complex with KLP68D, led to similar targeting errors of type III axons. Mutant phenotypes were at least partially reproduced by knockdown of each gene via RNA interference. Taken together, our data suggest the roles of Kinesin-2 proteins, including KLP68D and KLP64D, in ensuring proper synaptic wiring. PMID:26924931

  20. DNA and dispersal models highlight constrained connectivity in a migratory marine megavertebrate

    USGS Publications Warehouse

    Naro-Maciel, Eugenia; Hart, Kristen M.; Cruciata, Rossana; Putman, Nathan F.

    2016-01-01

    Population structure and spatial distribution are fundamentally important fields within ecology, evolution, and conservation biology. To investigate pan-Atlantic connectivity of globally endangered green turtles (Chelonia mydas) from two National Parks in Florida, USA, we applied a multidisciplinary approach comparing genetic analysis and ocean circulation modeling. The Everglades (EP) is a juvenile feeding ground, whereas the Dry Tortugas (DT) is used for courtship, breeding, and feeding by adults and juveniles. We sequenced two mitochondrial segments from 138 turtles sampled there from 2006-2015, and simulated oceanic transport to estimate their origins. Genetic and ocean connectivity data revealed northwestern Atlantic rookeries as the major natal sources, while southern and eastern Atlantic contributions were negligible. However, specific rookery estimates differed between genetic and ocean transport models. The combined analyses suggest that post-hatchling drift via ocean currents poorly explains the distribution of neritic juveniles and adults, but juvenile natal homing and population history likely play important roles. DT and EP were genetically similar to feeding grounds along the southern US coast, but highly differentiated from most other Atlantic groups. Despite expanded mitogenomic analysis and correspondingly increased ability to detect genetic variation, no significant differentiation between DT and EP, or among years, sexes or stages was observed. This first genetic analysis of a North Atlantic green turtle courtship area provides rare data supporting local movements and male philopatry. The study highlights the applications of multidisciplinary approaches for ecological research and conservation.

  1. Multilocus Phylogeny of the Afrotropical Freshwater Crab Fauna Reveals Historical Drainage Connectivity and Transoceanic Dispersal Since the Eocene.

    PubMed

    Daniels, Savel R; Phiri, Ethel E; Klaus, Sebastian; Albrecht, Christian; Cumberlidge, Neil

    2015-07-01

    Phylogenetic reconstruction, divergence time estimations and ancestral range estimation were undertaken for 66% of the Afrotropical freshwater crab fauna (Potamonautidae) based on four partial DNA loci (12S rRNA, 16S rRNA, cytochrome oxidase one [COI], and histone 3). The present study represents the most comprehensive taxonomic sampling of any freshwater crab family globally, and explores the impact of paleodrainage interconnectivity on cladogenesis among freshwater crabs. Phylogenetic analyses of the total evidence data using maximum-likelihood (ML), maximum parsimony (MP), and Bayesian inference (BI) produced a robust statistically well-supported tree topology that reaffirmed the monophyly of the Afrotropical freshwater crab fauna. The estimated divergence times suggest that the Afrotropical Potamonautidae diverged during the Eocene. Cladogenesis within and among several genera occurred predominantly during the Miocene, which was associated with major tectonic and climatic ameliorations throughout the region. Paleodrainage connectivity was observed with specimens from the Nilo-Sudan and East African coast proving to be sister to specimens from the Upper Guinea Forests in West Africa. In addition, we observed strong sister taxon affinity between specimens from East Africa and the Congo basin, including specimens from Lake Tanganyika, while the southern African fauna was retrieved as sister to the Angolan taxa. Within the East African clade we observed two independent transoceanic dispersal events, one to the Seychelles Archipelago and a second to Madagascar, while we observe a single transoceanic dispersal event from West Africa to São Tomé. The ancestral area estimation suggested a West African/East African ancestral range for the family with multiple dispersal events between southern Africa and East Africa, and between East Africa and Central Africa The taxonomic implications of our results are discussed in light of the widespread paraphyly evident among a

  2. Modeling vertical coral connectivity and mesophotic refugia

    NASA Astrophysics Data System (ADS)

    Holstein, Daniel M.; Paris, Claire B.; Vaz, Ana C.; Smith, Tyler B.

    2016-03-01

    Whether mesophotic reefs will behave as refugia for corals threatened by global climate change and coastal development depends on vertical exchange of larvae between diverse habitats. Here we use a biophysical model of larval dispersal to estimate vertical connectivity of a broadcasting ( Orbicella faveolata) and a brooding ( Porites astreoides) species of coral in the US Virgin Islands. Modeling predicts subsidy to shallow areas by mesophotic larvae of both species based on local hydrology, adult reproductive characteristics, larval traits, and a wide range of scenarios developed to test depth-sensitive factors, such as fertilization rates and post-settlement survivorship. In extreme model scenarios of reduced fertilization and post-settlement survivorship of mesophotic larvae, 1-10 % local mesophotic subsidy to shallow recruitment is predicted for both species, which are demographically significant. Although direct vertical connectivity is higher for the broadcaster, the brooder demonstrates higher local multigenerational vertical connectivity, which suggests that local P. astreoides populations are more resilient than those of O. faveolata, and corroborates field studies. As shallow habitat degrades, mesophotic-shallow subsidy is predicted to increase for both species. This study is the first of its kind to simulate larval dispersal and settlement between habitats of different depths, and these findings have local, regional, and global implications for predicting and managing coral reef persistence in a changing climate.

  3. Oceanic provinces and basin-scale connectivity derived from a hydrodynamical network help designing marine reserves in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    López, Cristóbal; Rossi, Vincent; Ser-Giacomi, Enrico; Hernandez-Garcia, Emilio

    2014-05-01

    Larval dispersal and marine connectivity have been identified as crucial factors for structuring marine population and thus to design Marine Protected Areas (MPAs). Focusing on larval dispersal by ocean currents, we propose a new approach coupling Lagrangian modeling and network theory which characterizes marine connectivity in the whole Mediterranean basin. Larvae of different Pelagic Larval Duration are modeled as passive tracers advected in a simulated oceanic surface flow from which a network of connected areas can be constructed. Hydrodynamical 'coherent' provinces extracted from this network are delimited by frontiers which match mesoscale oceanographic features. By examining the repeated occurrence of such boundaries, we identify the relevant scales of larval dispersal across the entire seascape. We finally used these hydrodynamical units to define connectivity metrics for a few selected MPAs in the Mediterranean sea and we discuss our results for future allocations of MPA. The characterization of marine connectivity and its geographic structure at basin-scale has ecological and managerial implications, especially considering the growing interests for offshore MPAs.

  4. Low connectivity between Mediterranean marine protected areas: a biophysical modeling approach for the dusky grouper Epinephelus marginatus.

    PubMed

    Andrello, Marco; Mouillot, David; Beuvier, Jonathan; Albouy, Camille; Thuiller, Wilfried; Manel, Stéphanie

    2013-01-01

    Marine protected areas (MPAs) are major tools to protect biodiversity and sustain fisheries. For species with a sedentary adult phase and a dispersive larval phase, the effectiveness of MPA networks for population persistence depends on connectivity through larval dispersal. However, connectivity patterns between MPAs remain largely unknown at large spatial scales. Here, we used a biophysical model to evaluate connectivity between MPAs in the Mediterranean Sea, a region of extremely rich biodiversity that is currently protected by a system of approximately a hundred MPAs. The model was parameterized according to the dispersal capacity of the dusky grouper Epinephelus marginatus, an archetypal conservation-dependent species, with high economic importance and emblematic in the Mediterranean. Using various connectivity metrics and graph theory, we showed that Mediterranean MPAs are far from constituting a true, well-connected network. On average, each MPA was directly connected to four others and MPAs were clustered into several groups. Two MPAs (one in the Balearic Islands and one in Sardinia) emerged as crucial nodes for ensuring multi-generational connectivity. The high heterogeneity of MPA distribution, with low density in the South-Eastern Mediterranean, coupled with a mean dispersal distance of 120 km, leaves about 20% of the continental shelf without any larval supply. This low connectivity, here demonstrated for a major Mediterranean species, poses new challenges for the creation of a future Mediterranean network of well-connected MPAs providing recruitment to the whole continental shelf. This issue is even more critical given that the expected reduction of pelagic larval duration following sea temperature rise will likely decrease connectivity even more. PMID:23861917

  5. Low Connectivity between Mediterranean Marine Protected Areas: A Biophysical Modeling Approach for the Dusky Grouper Epinephelus marginatus

    PubMed Central

    Andrello, Marco; Mouillot, David; Beuvier, Jonathan; Albouy, Camille; Thuiller, Wilfried; Manel, Stéphanie

    2013-01-01

    Marine protected areas (MPAs) are major tools to protect biodiversity and sustain fisheries. For species with a sedentary adult phase and a dispersive larval phase, the effectiveness of MPA networks for population persistence depends on connectivity through larval dispersal. However, connectivity patterns between MPAs remain largely unknown at large spatial scales. Here, we used a biophysical model to evaluate connectivity between MPAs in the Mediterranean Sea, a region of extremely rich biodiversity that is currently protected by a system of approximately a hundred MPAs. The model was parameterized according to the dispersal capacity of the dusky grouper Epinephelus marginatus, an archetypal conservation-dependent species, with high economic importance and emblematic in the Mediterranean. Using various connectivity metrics and graph theory, we showed that Mediterranean MPAs are far from constituting a true, well-connected network. On average, each MPA was directly connected to four others and MPAs were clustered into several groups. Two MPAs (one in the Balearic Islands and one in Sardinia) emerged as crucial nodes for ensuring multi-generational connectivity. The high heterogeneity of MPA distribution, with low density in the South-Eastern Mediterranean, coupled with a mean dispersal distance of 120 km, leaves about 20% of the continental shelf without any larval supply. This low connectivity, here demonstrated for a major Mediterranean species, poses new challenges for the creation of a future Mediterranean network of well-connected MPAs providing recruitment to the whole continental shelf. This issue is even more critical given that the expected reduction of pelagic larval duration following sea temperature rise will likely decrease connectivity even more. PMID:23861917

  6. Connectivity

    ERIC Educational Resources Information Center

    Grush, Mary, Ed.

    2006-01-01

    Connectivity has dramatically changed the landscape of higher education IT. From "on-demand" services for net-gen students and advanced eLearning systems for faculty, to high-performance computing grid resources for researchers, IT now provides more networked services than ever to connect campus constituents to each other and to the world.…

  7. Unusually limited pollen dispersal and connectivity of Pedunculate oak (Quercus robur) refugial populations at the species' southern range margin.

    PubMed

    Moracho, E; Moreno, G; Jordano, P; Hampe, A

    2016-07-01

    Low-latitudinal range margins of temperate and boreal plant species typically consist of scattered populations that persist locally in microrefugia. It remains poorly understood how their refugial habitats affect patterns of gene flow and connectivity, key components for their long-term viability and evolution. We examine landscape-scale patterns of historical and contemporary gene flow in refugial populations of the widespread European forest tree Pedunculate oak (Quercus robur) at the species' southwestern range margin. We sampled all adult trees (n = 135) growing in a 20 km long valley and genotyped 724 acorns from 72 mother trees at 17 microsatellite loci. The ten oak stands that we identified were highly differentiated and formed four distinct genetic clusters, despite sporadic historical dispersal being detectable. By far most contemporary pollination occurred within stands, either between local mates (85.6%) or through selfing (6.8%). Pollen exchange between stands (2.6%) was remarkably rare given their relative proximity and was complemented by long-distance pollen immigration (4.4%) and hybridization with the locally abundant Quercus pyrenaica (0.6%). The frequency of between-stand mating events decreased with increasing size and spatial isolation of stands. Overall, our results reveal outstandingly little long-distance gene flow for a wind-pollinated tree species. We argue that the distinct landscape characteristics of oaks' refugial habitats, with a combination of a rugged topography, dense vegetation and humid microclimate, are likely to increase plant survival but to hamper effective long-distance pollen dispersal. Moreover, local mating might be favoured by high tree compatibility resulting from genetic purging in these long-term relict populations. PMID:27146553

  8. Dispersal Patterns of Coastal Fish: Implications for Designing Networks of Marine Protected Areas

    PubMed Central

    Di Franco, Antonio; Gillanders, Bronwyn M.; De Benedetto, Giuseppe; Pennetta, Antonio; De Leo, Giulio A.; Guidetti, Paolo

    2012-01-01

    Information about dispersal scales of fish at various life history stages is critical for successful design of networks of marine protected areas, but is lacking for most species and regions. Otolith chemistry provides an opportunity to investigate dispersal patterns at a number of life history stages. Our aim was to assess patterns of larval and post-settlement (i.e. between settlement and recruitment) dispersal at two different spatial scales in a Mediterranean coastal fish (i.e. white sea bream, Diplodus sargus sargus) using otolith chemistry. At a large spatial scale (∼200 km) we investigated natal origin of fish and at a smaller scale (∼30 km) we assessed “site fidelity” (i.e. post-settlement dispersal until recruitment). Larvae dispersed from three spawning areas, and a single spawning area supplied post-settlers (proxy of larval supply) to sites spread from 100 to 200 km of coastline. Post-settlement dispersal occurred within the scale examined of ∼30 km, although about a third of post-settlers were recruits in the same sites where they settled. Connectivity was recorded both from a MPA to unprotected areas and vice versa. The approach adopted in the present study provides some of the first quantitative evidence of dispersal at both larval and post-settlement stages of a key species in Mediterranean rocky reefs. Similar data taken from a number of species are needed to effectively design both single marine protected areas and networks of marine protected areas. PMID:22355388

  9. Modelling dispersal dynamics of the early life stages of a marine flatfish (Solea solea L.)

    NASA Astrophysics Data System (ADS)

    Lacroix, Geneviève; Maes, Gregory E.; Bolle, Loes J.; Volckaert, Filip A. M.

    2013-11-01

    Connectivity throughout the life cycle of flatfish remains an open question, especially during the early life stages. Their effective management requires understanding of how spawning grounds and nurseries are connected and what processes influence larval retention and dispersal. The case of sole (Solea solea L.) is of particular interest because it is one of the most valuable commercial species in the North Sea, although stocks are chronically overexploited and variability in interannual recruitment is high. The transport of sole larvae from the spawning grounds to the nurseries is driven by hydrodynamic processes, but the final dispersal pattern and larval survival/abundance might be influenced by both behavioral and environmental factors. Therefore it is important to understand the relative impact of hydrodynamics, environment, behavior and ecophysiology on sole larval dispersal. Here we use a particle-tracking transport model coupled to a 3D hydro-dynamic model of the North Sea to investigate interannual variability of the transport of sole larvae over a 12-year period (1995-2006). A sensitivity analysis is performed to assess the relative impact of hydrodynamics, temperature and behavior on the recruitment dynamics to the nurseries. Four scenarios have been tested: (i) constant forcing of sea surface temperature during all years but varying meteorological forcing and river runoff, (ii) constant meteorological forcing during the whole period but varying sea surface temperature and river runoff, (iii) no vertical migration and (iv) an extended drift period (max. 30 days) before settlement if the larvae are not close to a suitable sediment type. Results suggest that year-to-year variability of larval supply to the nurseries is high, both in terms of abundance and larval source (balance between retention and dispersal). Sensitivity analysis shows that larval abundance at the end of the larval stage increases considerably if a settling delay is included. The impact

  10. Predicting connectivity of green turtles at Palmyra Atoll, central Pacific: a focus on mtDNA and dispersal modelling

    USGS Publications Warehouse

    Naro-Maciel, Eugenia; Gaughran, Stephen J.; Putman, Nathan F.; Amato, George; Arengo, Felicity; Dutton, Peter H.; McFadden, Katherine W.; Vintinner, Erin C.; Sterling, Eleanor J.

    2014-01-01

    Population connectivity and spatial distribution are fundamentally related to ecology, evolution and behaviour. Here, we combined powerful genetic analysis with simulations of particle dispersal in a high-resolution ocean circulation model to investigate the distribution of green turtles foraging at the remote Palmyra Atoll National Wildlife Refuge, central Pacific. We analysed mitochondrial sequences from turtles (n = 349) collected there over 5 years (2008–2012). Genetic analysis assigned natal origins almost exclusively (approx. 97%) to the West Central and South Central Pacific combined Regional Management Units. Further, our modelling results indicated that turtles could potentially drift from rookeries to Palmyra Atoll via surface currents along a near-Equatorial swathe traversing the Pacific. Comparing findings from genetics and modelling highlighted the complex impacts of ocean currents and behaviour on natal origins. Although the Palmyra feeding ground was highly differentiated genetically from others in the Indo-Pacific, there was no significant differentiation among years, sexes or stage-classes at the Refuge. Understanding the distribution of this foraging population advances knowledge of green turtles and contributes to effective conservation planning for this threatened species.

  11. Predicting connectivity of green turtles at Palmyra Atoll, central Pacific: a focus on mtDNA and dispersal modelling

    PubMed Central

    Naro-Maciel, Eugenia; Gaughran, Stephen J.; Putman, Nathan F.; Amato, George; Arengo, Felicity; Dutton, Peter H.; McFadden, Katherine W.; Vintinner, Erin C.; Sterling, Eleanor J.

    2014-01-01

    Population connectivity and spatial distribution are fundamentally related to ecology, evolution and behaviour. Here, we combined powerful genetic analysis with simulations of particle dispersal in a high-resolution ocean circulation model to investigate the distribution of green turtles foraging at the remote Palmyra Atoll National Wildlife Refuge, central Pacific. We analysed mitochondrial sequences from turtles (n = 349) collected there over 5 years (2008–2012). Genetic analysis assigned natal origins almost exclusively (approx. 97%) to the West Central and South Central Pacific combined Regional Management Units. Further, our modelling results indicated that turtles could potentially drift from rookeries to Palmyra Atoll via surface currents along a near-Equatorial swathe traversing the Pacific. Comparing findings from genetics and modelling highlighted the complex impacts of ocean currents and behaviour on natal origins. Although the Palmyra feeding ground was highly differentiated genetically from others in the Indo-Pacific, there was no significant differentiation among years, sexes or stage-classes at the Refuge. Understanding the distribution of this foraging population advances knowledge of green turtles and contributes to effective conservation planning for this threatened species. PMID:24451389

  12. Exploration of the “larval pool”: development and ground-truthing of a larval transport model off leeward Hawai‘i

    PubMed Central

    Kobayashi, Donald R.

    2016-01-01

    Most adult reef fish show site fidelity thus dispersal is limited to the mobile larval stage of the fish, and effective management of such species requires an understanding of the patterns of larval dispersal. In this study, we assess larval reef fish distributions in the waters west of the Big Island of Hawai‘i using both in situ and model data. Catches from Cobb midwater trawls off west Hawai‘i show that reef fish larvae are most numerous in offshore waters deeper than 3,000 m and consist largely of pre-settlement Pomacanthids, Acanthurids and Chaetodontids. Utilizing a Lagrangian larval dispersal model, we were able to replicate the observed shore fish distributions from the trawl data and we identified the 100 m depth strata as the most likely depth of occupancy. Additionally, our model showed that for larval shore fish with a pelagic larval duration longer than 40 days there was no significant change in settlement success in our model. By creating a general additive model (GAM) incorporating lunar phase and angle we were able to explain 67.5% of the variance between modeled and in situ Acanthurid abundances. We took steps towards creating a predictive larval distribution model that will greatly aid in understanding the spatiotemporal nature of the larval pool in west Hawai‘i, and the dispersal of larvae throughout the Hawaiian archipelago. PMID:26855873

  13. Population divergences despite long pelagic larval stages: lessons from crocodile icefishes (Channichthyidae).

    PubMed

    Damerau, M; Matschiner, M; Salzburger, W; Hanel, R

    2014-02-01

    Dispersal via pelagic larval stages plays a key role in population connectivity of many marine species. The degree of connectivity is often correlated with the time that larvae spend in the water column. The Antarctic notothenioid fishes develop through an unusually long pelagic larval phase often exceeding 1 year. Notothenioids thus represent a prime model system for studying the influence of prolonged larval phases on population structure in otherwise demersal species. Here, we compare the population genetic structure and demographic history of two sub-Antarctic crocodile icefish species (Chaenocephalus aceratus and Champsocephalus gunnari) from the Scotia Arc and Bouvet Island in the Atlantic sector of the Southern Ocean to delineate the relative importance of species-specific, oceanographic and paleoclimatic factors to gene flow. Based on 7 (C. aceratus) and 8 (C. gunnari) microsatellites, as well as two mitochondrial DNA markers (cytochrome b, D-loop), we detect pronounced population genetic structure in both species (amova FSTs range from 0.04 to 0.53). High genetic similarities were found concordantly in the populations sampled at the Southern Scotia Arc between Elephant Island and South Orkney Islands, whereas the populations from Bouvet Island, which is located far to the east of the Scotia Arc, are substantially differentiated from those of the Scotia Arc region. Nonetheless, haplotype genealogies and Bayesian cluster analyses suggest occasional gene flow over thousands of kilometres. Higher divergences between populations of C. gunnari as compared to C. aceratus are probably caused by lower dispersal capabilities and demographic effects. Bayesian skyline plots reveal population size reductions during past glacial events in both species with an estimated onset of population expansions about 25 000 years ago. PMID:24372945

  14. The development of the Drosophila larval brain.

    PubMed

    Hartenstein, Volker; Spindler, Shana; Pereanu, Wayne; Fung, Siaumin

    2008-01-01

    In this chapter we will start out by describing in more detail the progenitors of the nervous system, the neuroblasts and ganglion mother cells. Subsequently we will survey the generic cell types that make up the developing Drosophila brain, namely neurons, glial cells and tracheal cells. Finally, we will attempt a synopsis of the neuronal connectivity of the larval brain that can be deduced from the analysis of neural lineages and their relationship to neuropile compartments. PMID:18683635

  15. 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

  16. 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

  17. Linking basin-scale connectivity, oceanography and population dynamics for the management of marine ecosystems in the Mediterranean sea

    NASA Astrophysics Data System (ADS)

    Rossi, Vincent; Dubois, Mélodie; Ser-Giacomi, Enrico; Arnaud-Haond, Sophie; Lopez, Cristobal; Hernandez-Garcia, Emilio

    2015-04-01

    A major challenge in marine ecology is to describe properly larval dispersal and marine connectivity since they structure marine populations and are thus crucial criteria to design Marine Protected Areas (MPAs). Focusing on larval dispersal by ocean currents in the entire Mediterranean Sea, I present a new approach coupling Lagrangian modeling and Network Theory tools to characterize broad-scale connectivity of marine populations. The Mediterranean basin is subdivided into an ensemble of sub-regions that are interconnected through oceanic transport. Passive larvae of different pelagic durations and seasons are advected in a simulated surface flow from which a network of connected areas is constructed. First, the global analysis of the transport network using a community detection algorithm enables the extraction of hydrodynamical provinces which are delimited by frontiers matching multiscale oceanographic features. By examining the repeated occurrence of such boundaries, we identify the spatial scales and geographic structures that control larval dispersal across the entire seascape. We also analyze novel connectivity metrics for the existing marine reserves and we discussed our results in the context of ocean biogeography and MPAs design. Secondly, we studied the local properties of the network with the computation of proxies commonly used in population ecology to measure local retention, self-recruitment and larval sources/sinks. Our results confirmed that retention processes are favored along certain coastlines due to specific oceanographic conditions while they are weak in the open ocean. Moreover, we found that divergent (convergent) oceanic zones resulting from Ekman theory are systematically characterized by larval sources (sinks). Finally, although these proxies are often studied separately in the literature, we suggest they are inter-related under certain conditions. Their integrated interpretation leads to a better understanding of population dynamics and

  18. Rapid declines in metabolism explain extended coral larval longevity

    NASA Astrophysics Data System (ADS)

    Graham, E. M.; Baird, A. H.; Connolly, S. R.; Sewell, M. A.; Willis, B. L.

    2013-06-01

    Lecithotrophic, or non-feeding, marine invertebrate larvae generally have shorter pelagic larval durations (PLDs) than planktotrophic larvae. However, non-feeding larvae of scleractinian corals have PLDs far exceeding those of feeding larvae of other organisms and predictions of PLD based on energy reserves and metabolic rates, raising questions about how such longevity is achieved. Here, we measured temporal changes in metabolic rates and total lipid content of non-feeding larvae of four species of reef corals to determine whether changes in energy utilization through time contribute to extended larval durations. The temporal dynamics of both metabolic rates and lipid content were highly consistent among species. Prior to fertilization, metabolic rates were low (2.73-8.63 nmol O2 larva-1 h-1) before rapidly increasing to a peak during embryogenesis and early development 1-2 days after spawning. Metabolic rates remained high until shortly after larvae first became competent to metamorphose and then declined by up to two orders of magnitude to levels at or below rates seen in unfertilized eggs over the following week. Larvae remained in this state of low metabolic activity for up to 2 months. Consistent with temporal patterns in metabolic rates, depletion of lipids was extremely rapid during early development and then slowed dramatically from 1 week onward. Despite the very low metabolic rates in these species, larvae continued to swim and retained competence for at least 2 months. The capacity of non-feeding coral larvae to enter a state of low metabolism soon after becoming competent to metamorphose significantly extends dispersal potential, thereby accruing advantages typically associated with planktotrophy, notably enhanced population connectivity.

  19. Modelling the transport of common sole larvae in the southern North Sea: Influence of hydrodynamics and larval vertical movements

    NASA Astrophysics Data System (ADS)

    Savina, Marie; Lacroix, Geneviève; Ruddick, Kevin

    2010-04-01

    In the present work we used a particle-tracking model coupled to a 3D hydrodynamic model to study the combined effect of hydrodynamic variability and active vertical movements on the transport of sole larvae in the southern North Sea. Larval transport from the 6 main spawning grounds was simulated during 40 day periods starting on 2 plausible spawning dates, the 15/04 and the 01/05, during 2 years, 1995 and 1996. In addition to a "passive" behaviour, 3 types of active vertical movements inspired from previous studies have been tested: (1) Eggs and early larvae float in the surface waters, late larvae migrate toward the bottom and stay there until the end of the simulation; (2 and 3) Eggs float in the surface waters, early larvae perform diel vertical migrations in the surface waters, and (2) Late larvae perform diel vertical migrations in the bottom waters until the end of the simulation; or (3) Late larvae perform tidally synchronised vertical migrations in the bottom waters until the end of the simulation. These behaviours have been implemented in the model with vertical migration rates, positive or negative, which can account for buoyancy or real swimming activity. Variations in larval transport were analysed in terms of mean trajectories, final larvae distribution, larval retention above nurseries, and connectivity. Results suggest that the variations in larval retention above nurseries due to the varying hydrodynamic conditions are not consistent in space i.e. not the same for all the spawning sites. The effect of active vertical movements on larval transport is also not consistent in space: Effects of active vertical movements include decreased retention above nurseries, decreased transport and/or decreased horizontal dispersion of larvae through reduced vertical shear (depending on the zone). The variability in larval retention due to hydrodynamic variability is higher than variability due to differences in the behaviour of larvae. In terms of connectivity

  20. Linking River Morphology to Larval Drift of an Endangered Sturgeon

    NASA Astrophysics Data System (ADS)

    Bazzetta, L.; Jacobson, R. B.; Braaten, P. J.; Elliott, C. M.; Reuter, J. M.

    2009-12-01

    Computational models developed to calculate longitudinal advection and dispersion of contaminants in rivers have potential application in predicting larval drift. A critical component of this family of models is the longitudinal dispersion coefficient which parameterizes the processes that retain and distribute a contaminant along the river. Here we evaluate the potential for longitudinal dispersion coefficients to characterize larval drift of the endangered pallid sturgeon (Scaphirhynchus albus) in various segments of the free-flowing Missouri River ranging from Missouri to Montana. We randomly selected transects of acoustic Doppler current profiler (ADCP) flow velocity data from reach-scale datasets that were collected in the Missouri River from 2002-2008 under comparable discharge conditions. We used previously developed equations (Kim and others, 2007) to calculate a one-dimensional longitudinal dispersion coefficient for each ADCP transect. We compared the statistical distributions of these coefficients for 2 to 6 reaches chosen from each of six geomorphic segments of the Missouri. Distributional patterns indicate that dispersion coefficients relate to observed variation in hydrology and geomorphology of the channel at the segment scale. Although one-dimensional dispersion analysis demonstrates potential as a tool for estimating pallid sturgeon larval drift and habitat suitability in unchannelized portions of the Missouri River, the large spatial variation in calculated dispersion coefficients resulting from river-training structures (wing dikes) in the Lower Missouri complicates selection of appropriate values. Recent data indicating that pallid sturgeon larvae occur in greater concentration in the thalweg indicate that the majority of larvae may bypass these structures and their associated retentive eddies. A two-dimensional space-averaged dispersion calculation and analysis may more accurately characterize the potential drift times and distances of larval

  1. 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. PMID:26641083

  2. 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

  3. Genetic Diversity and Local Connectivity in the Mediterranean Red Gorgonian Coral after Mass Mortality Events.

    PubMed

    Pilczynska, Joanna; Cocito, Silvia; Boavida, Joana; Serrão, Ester; Queiroga, Henrique

    2016-01-01

    Estimating the patterns of connectivity in marine taxa with planktonic dispersive stages is a challenging but crucial task because of its conservation implications. The red gorgonian Paramuricea clavata is a habitat forming species, characterized by short larval dispersal and high reproductive output, but low recruitment. In the recent past, the species was impacted by mass mortality events caused by increased water temperatures in summer. In the present study, we used 9 microsatellites to investigate the genetic structure and connectivity in the highly threatened populations from the Ligurian Sea (NW Mediterranean). No evidence for a recent bottleneck neither decreased genetic diversity in sites impacted by mass mortality events were found. Significant IBD pattern and high global FST confirmed low larval dispersal capability in the red gorgonian. The maximum dispersal distance was estimated at 20-60 km. Larval exchange between sites separated by hundreds of meters and between different depths was detected at each site, supporting the hypothesis that deeper subpopulations unaffected by surface warming peaks may provide larvae for shallower ones, enabling recovery after climatically induced mortality events. PMID:26982334

  4. Genetic Diversity and Local Connectivity in the Mediterranean Red Gorgonian Coral after Mass Mortality Events

    PubMed Central

    Pilczynska, Joanna; Cocito, Silvia; Boavida, Joana; Serrão, Ester; Queiroga, Henrique

    2016-01-01

    Estimating the patterns of connectivity in marine taxa with planktonic dispersive stages is a challenging but crucial task because of its conservation implications. The red gorgonian Paramuricea clavata is a habitat forming species, characterized by short larval dispersal and high reproductive output, but low recruitment. In the recent past, the species was impacted by mass mortality events caused by increased water temperatures in summer. In the present study, we used 9 microsatellites to investigate the genetic structure and connectivity in the highly threatened populations from the Ligurian Sea (NW Mediterranean). No evidence for a recent bottleneck neither decreased genetic diversity in sites impacted by mass mortality events were found. Significant IBD pattern and high global FST confirmed low larval dispersal capability in the red gorgonian. The maximum dispersal distance was estimated at 20–60 km. Larval exchange between sites separated by hundreds of meters and between different depths was detected at each site, supporting the hypothesis that deeper subpopulations unaffected by surface warming peaks may provide larvae for shallower ones, enabling recovery after climatically induced mortality events. PMID:26982334

  5. Low Rate of Between-Population Seed Dispersal Restricts Genetic Connectivity and Metapopulation Dynamics in a Clonal Shrub

    PubMed Central

    Merwin, Laura; He, Tianhua; Lamont, Byron B.; Enright, Neal J.; Krauss, Siegfried L.

    2012-01-01

    Clonal species normally have low seed production, low recruitment rates and long lifespans, and it is expected that the rates of long-distance dispersal (LDD) of seeds will be low as well. Banksia candolleana is a clonal shrub in Mediterranean-type, fire-prone sclerophyll shrublands of southwestern Australia, whose reproductive biology and population dynamics contrast with those of co-occurring nonclonal congeneric species, all of which are restricted to a mosaic of sand dunes set within a matrix of inhospitable swales. Using microsatellite markers, we genotyped 499 plants in all 15 populations of B. candolleana within a 12-km2 area, assessed population genetic differentiation, and quantified the effective rate of interpopulation seed dispersal through genetic assignment of individuals to populations. We measured life history, reproductive and demographic attributes, and compared these with two co-occurring Banksia species, a non-clonal resprouter and a nonsprouter. B. candolleana has much higher levels of population genetic differentiation, and one-third the rate of interpopulation seed migration, as the other two species (2.2% vs 5.5−6.8% of genotyped plants inferred to be immigrants), though distances reached by LDD are comparable (0.3−2.3 km). The low rate of interpopulation dispersal was supported by an analysis of the age structure of three populations that suggests a mean interdune migration rate of <800 m in 200 years, and 60% of suitable dunes remain uninhabited. Thus, B. candolleana has poor properties for promoting long-distance dispersal. It is unclear if these are idiosyncratic to this species or whether such properties are to be expected of clonal species in general where LDD is less critical for species survival. PMID:23209839

  6. Contrasting levels of connectivity and localised persistence characterise the latitudinal distribution of a wind-dispersed rainforest canopy tree.

    PubMed

    Heslewood, Margaret M; Lowe, Andrew J; Crayn, Darren M; Rossetto, Maurizio

    2014-06-01

    Contrasting signals of genetic divergence due to historic and contemporary gene flow were inferred for Coachwood, Ceratopetalum apetalum (Cunoniaceae), a wind-dispersed canopy tree endemic to eastern Australian warm temperate rainforest. Analysis of nine nuclear microsatellites across 22 localities revealed two clusters between northern and southern regions and with vicariance centred on the wide Hunter River Valley. Within populations diversity was high indicating a relatively high level of pollen dispersal among populations. Genetic variation was correlated to differences in regional biogeography and ecology corresponding to IBRA regions, primary factors being soil type and rainfall. Eleven haplotypes were identified by chloroplast microsatellite analysis from the same 22 localities. A lack of chloroplast diversity within sites demonstrates limited gene flow via seed dispersal. Network representation indicated regional sharing of haplotypes indicative of multiple Pleistocene refugia as well as deep divergences between regional elements of present populations. Chloroplast differentiation between sites in the upper and lower sections of the northern population is reflective of historic vicariance at the Clarence River Corridor. There was no simple vicariance explanation for the distribution of the divergent southern chlorotype, but its distribution may be explained by the effects of drift from a larger initial gene pool. Both the Hunter and Clarence River Valleys represent significant dry breaks within the species range, consistent with this species being rainfall dependent rather than cold-adapted. PMID:24898671

  7. 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.

  8. Effects of Habitat Fragmentation on Abundance, Larval Food and Parasitism of a Spider-Hunting Wasp

    PubMed Central

    Coudrain, Valérie; Herzog, Felix; Entling, Martin H.

    2013-01-01

    Habitat fragmentation strongly affects species distribution and abundance. However, mechanisms underlying fragmentation effects often remain unresolved. Potential mechanisms are (1) reduced dispersal of a species or (2) altered species interactions in fragmented landscapes. We studied if abundance of the spider-hunting and cavity-nesting wasp Trypoxylon figulus Linnaeus (Hymenoptera: Crabronidae) is affected by fragmentation, and then tested for any effect of larval food (bottom up regulation) and parasitism (top down regulation). Trap nests of T. figulus were studied in 30 agricultural landscapes of the Swiss Plateau. The sites varied in the level of isolation from forest (adjacent, in the open landscape but connected, isolated) and in the amount of woody habitat (from 4 % to 74 %). We recorded wasp abundance (number of occupied reed tubes), determined parasitism of brood cells and analysed the diversity and abundance of spiders that were deposited as larval food. Abundances of T. figulus were negatively related to forest cover in the landscape. In addition, T. figulus abundances were highest at forest edges, reduced by 33.1% in connected sites and by 79.4% in isolated sites. The mean number of spiders per brood cell was lowest in isolated sites. Nevertheless, structural equation modelling revealed that this did not directly determine wasp abundance. Parasitism was neither related to the amount of woody habitat nor to isolation and did not change with host density. Therefore, our study showed that the abundance of T. figulus cannot be fully explained by the studied trophic interactions. Further factors, such as dispersal and habitat preference, seem to play a role in the population dynamics of this widespread secondary carnivore in agricultural landscapes. PMID:23516622

  9. Geographic Patterns of Genetic Connectivity Among Lophelia pertusa Deep Coral Populations in the Western North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Morrison, C. L.; King, T. L.; Johnson, R. L.; Ross, S. W.; Nizinski, M. S.

    2008-05-01

    Lophelia pertusa, a cosmopolitan species, is the dominant structure-forming scleractinian coral on the continental slope in the western North Atlantic Ocean (WNAO) off of the southeastern U.S. coast and in the Gulf of Mexico (GOM). Little is known about this coral's basic biology, including larval dispersal and population connectivity, yet adverse impacts from human activities is documented. Using a suite of twelve microsatellite markers, we assessed the spatial scale and pattern of genetic connectivity among wide-spread L. pertusa populations by determining multi-locus genotypes for approximately 350 L. pertusa individuals from 20 sites in the WNAO, GOM and eastern North Atlantic Ocean (i.e., off Scotland). Quantitative estimates of hierarchical gene diversity (AMOVA) indicated significant population structure between the three regions and within the GOM and WNAO. Patterns of population connectivity were complex. We found evidence for incomplete mixing at smaller spatial scales suggesting retention of larvae. Additionally, we found instances of increased connectivity across broader geographic distances suggesting that some larvae are broadly dispersed. Thus, dispersal of L. pertusa larvae appears to be localized generally, but long distance dispersal must occur with enough frequency that there remains some regional genetic cohesion within the GOM and WNAO. To the extent possible, local and regional hydrodynamic patterns that may influence larval dispersal will be discussed.

  10. A larval Devonian lungfish.

    PubMed

    Thomson, Keith S; Sutton, Mark; Thomas, Bethia

    2003-12-18

    Perhaps the most enduring of puzzles in palaeontology has been the identity of Palaeospondylus gunni Traquair, a tiny (5-60-mm) vertebrate fossil from the Middle Devonian period (approximately 385 Myr ago) of Scotland, first discovered in 1890 (refs 1-3). It is known principally from a single site (Achanarras Quarry, Caithness) where, paradoxically, it is extremely abundant, preserved in varved lacustrine deposits along with 13 other genera of fishes. Here we show that Palaeospondylus is the larval stage of a lungfish, most probably Dipterus valenciennesi Sedgwick and Murchison 1828 (ref. 5), and that development of the adult form requires a distinct metamorphosis. Palaeospondylus is the oldest known true larva of a vertebrate. PMID:14685237

  11. Larval descriptions of the family Porcellanidae: A worldwide annotated compilation of the literature (Crustacea, Decapoda).

    PubMed

    Vela, María José; González-Gordillo, Juan Ignacio

    2016-01-01

    For most of the family Porcellanidae, which comprises 283 species, larval development remains to be described. Full development has been only described for 52 species, while part of the larval cycle has been described for 45 species. The importance of knowing the complete larval development of a species goes beyond allowing the identification of larval specimens collected in the plankton. Morphological larval data also constitute a support to cladistic techniques used in the establishment of the phylogenetic status (see Hiller et al. 2006, Marco-Herrero et al. 2013). Nevertheless, the literature on the larval development of this family is old and widely dispersed and in many cases it is difficult to collect the available information on a particular taxon. Towards the aim of facilitating future research, all information available on the larval development of porcellanids has been compiled. Following the taxonomic checklist of Porcellanidae proposed by Osawa and McLaughlin (2010), a checklist has been prepared that reflects the current knowledge about larval development of the group including larval stages and the method used to obtain the larvae, together with references. Those species for which the recognised names have been changed according to Osawa and McLaughlin (2010) are indicated. PMID:27081332

  12. Location Isn’t Everything: Timing of Spawning Aggregations Optimizes Larval Replenishment

    PubMed Central

    Donahue, Megan J.; Karnauskas, Mandy; Toews, Carl; Paris, Claire B.

    2015-01-01

    Many species of reef fishes form large spawning aggregations that are highly predictable in space and time. Prior research has suggested that aggregating fish derive fitness benefits not just from mating at high density but, also, from oceanographic features of the spatial locations where aggregations occur. Using a probabilistic biophysical model of larval dispersal coupled to a fine resolution hydrodynamic model of the Florida Straits, we develop a stochastic landscape of larval fitness. Tracking virtual larvae from release to settlement and incorporating changes in larval behavior through ontogeny, we found that larval success was sensitive to the timing of spawning. Indeed, propagules released during the observed spawning period had higher larval success rates than those released outside the observed spawning period. In contrast, larval success rates were relatively insensitive to the spatial position of the release site. In addition, minimum (rather than mean) larval survival was maximized during the observed spawning period, indicating a reproductive strategy that minimizes the probability of recruitment failure. Given this landscape of larval fitness, we take an inverse optimization approach to define a biological objective function that reflects a tradeoff between the mean and variance of larval success in a temporally variable environment. Using this objective function, we suggest that the length of the spawning period can provide insight into the tradeoff between reproductive risk and reward. PMID:26103162

  13. Larval descriptions of the family Porcellanidae: A worldwide annotated compilation of the literature (Crustacea, Decapoda)

    PubMed Central

    Vela, María José; González-Gordillo, Juan Ignacio

    2016-01-01

    Abstract For most of the family Porcellanidae, which comprises 283 species, larval development remains to be described. Full development has been only described for 52 species, while part of the larval cycle has been described for 45 species. The importance of knowing the complete larval development of a species goes beyond allowing the identification of larval specimens collected in the plankton. Morphological larval data also constitute a support to cladistic techniques used in the establishment of the phylogenetic status (see Hiller et al. 2006, Marco-Herrero et al. 2013). Nevertheless, the literature on the larval development of this family is old and widely dispersed and in many cases it is difficult to collect the available information on a particular taxon. Towards the aim of facilitating future research, all information available on the larval development of porcellanids has been compiled. Following the taxonomic checklist of Porcellanidae proposed by Osawa and McLaughlin (2010), a checklist has been prepared that reflects the current knowledge about larval development of the group including larval stages and the method used to obtain the larvae, together with references. Those species for which the recognised names have been changed according to Osawa and McLaughlin (2010) are indicated. PMID:27081332

  14. Location Isn't Everything: Timing of Spawning Aggregations Optimizes Larval Replenishment.

    PubMed

    Donahue, Megan J; Karnauskas, Mandy; Toews, Carl; Paris, Claire B

    2015-01-01

    Many species of reef fishes form large spawning aggregations that are highly predictable in space and time. Prior research has suggested that aggregating fish derive fitness benefits not just from mating at high density but, also, from oceanographic features of the spatial locations where aggregations occur. Using a probabilistic biophysical model of larval dispersal coupled to a fine resolution hydrodynamic model of the Florida Straits, we develop a stochastic landscape of larval fitness. Tracking virtual larvae from release to settlement and incorporating changes in larval behavior through ontogeny, we found that larval success was sensitive to the timing of spawning. Indeed, propagules released during the observed spawning period had higher larval success rates than those released outside the observed spawning period. In contrast, larval success rates were relatively insensitive to the spatial position of the release site. In addition, minimum (rather than mean) larval survival was maximized during the observed spawning period, indicating a reproductive strategy that minimizes the probability of recruitment failure. Given this landscape of larval fitness, we take an inverse optimization approach to define a biological objective function that reflects a tradeoff between the mean and variance of larval success in a temporally variable environment. Using this objective function, we suggest that the length of the spawning period can provide insight into the tradeoff between reproductive risk and reward. PMID:26103162

  15. The relationship between pelagic larval duration and range size in tropical reef fishes: a synthetic analysis

    PubMed Central

    Lester, Sarah E; Ruttenberg, Benjamin I

    2005-01-01

    We address the conflict in earlier results regarding the relationship between dispersal potential and range size. We examine all published pelagic larval duration data for tropical reef fishes. Larval duration is a convenient surrogate for dispersal potential in marine species that are sedentary as adults and that therefore only experience significant dispersal during their larval phase. Such extensive quantitative dispersal data are only available for fishes and thus we use a unique dataset to examine the relationship between dispersal potential and range size. We find that dispersal potential and range size are positively correlated only in the largest ocean basin, the Indo-Pacific, and that this pattern is driven primarily by the spatial distribution of habitat and dispersal barriers. Furthermore, the relationship strengthens at higher taxonomic levels, suggesting an evolutionary mechanism. We document a negative correlation between species richness and larval duration at the family level in the Indo-Pacific, implying that speciation rate may be negatively related to dispersal potential. If increased speciation rate within a taxonomic group results in smaller range sizes within that group, speciation rate could regulate the association between range size and dispersal potential. PMID:16007745

  16. The importance of chain connectivity in the formation of non-covalent interactions between polymers and single-walled carbon nanotubes and its impact on dispersion

    SciTech Connect

    Linton, Dias; Driva, Paraskevi; Ivanov, Ilia N; Geohegan, David B; Feigerle, Charles S; Dadmun, Mark D

    2010-05-01

    In this study we investigate the formation of non-covalent electron donor acceptor (EDA) interactions between polymers and single-walled carbon nanotubes (SWNTs) with the goal of optimizing interfacial adhesion and homogeneity of nanocomposites without modifying the SWNT native surface. Nanocomposites of SWNTs and three sets of polymer matrices with varying composition of electron donating 2-(dimethylamino)ethyl methacrylate (DMAEMA) or electron accepting acrylonitrile (AN) and cyanostyrene (CNSt) were prepared, quantitatively characterized by optical microscopy and Raman spectroscopy (Raman mapping, Raman D* peak shifts) and qualitatively compared through thick film composite visualization. The experimental data show that copolymers with 30 mol% DMAEMA, 45 mol% AN, 23 mol% CNSt and polyacrylonitrile homopolymer have the highest extent of intermolecular interaction, which translates to an optimum SWNT spatial dispersion among the series. These results are found to correlate very well with the intermolecular interaction energies obtained from quantum density functional theory calculations. Both experimental and computational results also illustrate that chain connectivity is critical in controlling the accessibility of the functional groups to form intermolecular interactions. This means that an adequate distance between interacting functional groups on a polymer chain is needed in order to allow efficient intermolecular contact. Thus, controlling the amount of electron donating or withdrawing moieties throughout the polymer chain will direct the extent of EDA interaction, which enables tuning the SWNT dispersion.

  17. The importance of chain connectivity in the formation of non-covalent interactions between polymers and single-walled carbon nanotubes and its impact on dispersion

    SciTech Connect

    Sumpter, Bobby G; Dadmun, Mark D; Driva, Paraskevi; Ivanov, Ilia N; Geohegan, David B; Linton, Dias; Feigerle, Charles S

    2010-01-01

    In this study we investigate the formation of non-covalent electron donor acceptor (EDA) interactions between polymers and single-walled carbon nanotubes (SWNTs) with the goal of optimizing interfacial adhesion and homogeneity of nanocomposites without modifying the SWNT native surface. Nanocomposites of SWNTs and three sets of polymer matrices with varying composition of electron donating 2-(dimethylamino)ethyl methacrylate (DMAEMA) or electron accepting acrylonitrile (AN) and cyanostyrene (CNSt) were prepared, quantitatively characterized by optical microscopy and Raman spectroscopy (Raman mapping, Raman D* peak shifts) and qualitatively compared through thick film composite visualization. The experimental data show that copolymers with 30 mol% DMAEMA, 45 mol% AN, 23 mol% CNSt and polyacrylonitrile homopolymer have the highest extent of intermolecular interaction, which translates to an optimum SWNT spatial dispersion among the series. These results are found to correlate very well with the intermolecular interaction energies obtained from quantum density functional theory calculations. Both experimental and computational results also illustrate that chain connectivity is critical in controlling the accessibility of the functional groups to form intermolecular interactions. This means that an adequate distance between interacting functional groups on a polymer chain is needed in order to allow efficient intermolecular contact. Thus, controlling the amount of electron donating or withdrawing moieties throughout the polymer chain will direct the extent of EDA interaction, which enables tuning the SWNT dispersion.

  18. Long-distance dispersal, low connectivity and molecular evidence of a new cryptic species in the obligate rafter Caprella andreae Mayer, 1890 (Crustacea: Amphipoda: Caprellidae)

    NASA Astrophysics Data System (ADS)

    Cabezas, M. Pilar; Navarro-Barranco, Carlos; Ros, Macarena; Guerra-García, José Manuel

    2013-09-01

    The amphipod Caprella andreae Mayer, 1890 was recorded for the first time in Southern Iberian Peninsula (36°44'15″N, 3°59'38″W). This species is the only obligate rafter of the suborder Caprellidea and has been reported to attach not only to floating objects such as ropes or driftwoods but also to turtle carapaces. Mitochondrial and nuclear markers were used to examine dispersal capabilities and population genetic structure of C. andreae across seven localities in the Mediterranean and Atlantic Ocean collected from floating substrata with different dispersal patterns. The strong population differentiation with no haplotypes shared between populations suggests that C. andreae is quite faithful to the substratum on which it settles. In addition, the proportionally higher genetic diversity displayed in populations living on turtles as well as the presence of highly differentiated haplotypes in the same turtle population may be indicative that these populations survive longer, which could lead C. andreae to prefer turtles instead of floating objects to settle and disperse. Therefore, rafting on floating objects may be sporadic, and ocean currents would not be the most important factor shaping patterns of connectivity and population structure in this species. Furthermore, molecular phylogenetic analyses revealed the existence of a cryptic species whose estimates of genetic divergence are higher than those estimated between C. andreae and other congeneric species (e.g. Caprella dilatata and Caprella penantis). Discovery of cryptic species among widely distributed small marine invertebrates is quite common and, in this case, prompts for a more detailed phylogenetic analysis and taxonomic revision of genus Caprella. On the other hand, this study also means the first record of the gammarids Jassa cadetta and Elasmopus brasiliensis and the caprellid Caprella hirsuta on drifting objects.

  19. Oceanographic Currents and Local Ecological Knowledge Indicate, and Genetics Does Not Refute, a Contemporary Pattern of Larval Dispersal for The Ornate Spiny Lobster, Panulirus ornatus in the South-East Asian Archipelago

    PubMed Central

    Dao, Hoc Tan; Smith-Keune, Carolyn; Wolanski, Eric; Jones, Clive M.; Jerry, Dean R.

    2015-01-01

    Here we utilize a combination of genetic data, oceanographic data, and local ecological knowledge to assess connectivity patterns of the ornate spiny lobster Panulirus ornatus (Fabricius, 1798) in the South-East Asian archipelago from Vietnam to Australia. Partial mitochondrial DNA control region and 10 polymorphic microsatellites did not detect genetic structure of 216 wild P. ornatus samples from Australia, Indonesia and Vietnam. Analyses show no evidence for genetic differentiation among populations (mtDNA control region sequences ΦST = -0.008; microsatellite loci FST = 0.003). A lack of evidence for regional or localized mtDNA haplotype clusters, or geographic clusters of microsatellite genotypes, reveals a pattern of high gene flow in P. ornatus throughout the South-East Asian Archipelago. This lack of genetic structure may be due to the oceanography-driven connectivity of the pelagic lobster larvae between spawning grounds in Papua New Guinea, the Philippines and, possibly, Indonesia. The connectivity cycle necessitates three generations. The lack of genetic structure of P. ornatus population in the South-East Asian archipelago has important implications for the sustainable management of this lobster in that the species within the region needs to be managed as one genetic stock. PMID:25951344

  20. Oceanographic Currents and Local Ecological Knowledge Indicate, and Genetics Does Not Refute, a Contemporary Pattern of Larval Dispersal for The Ornate Spiny Lobster, Panulirus ornatus in the South-East Asian Archipelago.

    PubMed

    Dao, Hoc Tan; Smith-Keune, Carolyn; Wolanski, Eric; Jones, Clive M; Jerry, Dean R

    2015-01-01

    Here we utilize a combination of genetic data, oceanographic data, and local ecological knowledge to assess connectivity patterns of the ornate spiny lobster Panulirus ornatus (Fabricius, 1798) in the South-East Asian archipelago from Vietnam to Australia. Partial mitochondrial DNA control region and 10 polymorphic microsatellites did not detect genetic structure of 216 wild P. ornatus samples from Australia, Indonesia and Vietnam. Analyses show no evidence for genetic differentiation among populations (mtDNA control region sequences ΦST = -0.008; microsatellite loci FST = 0.003). A lack of evidence for regional or localized mtDNA haplotype clusters, or geographic clusters of microsatellite genotypes, reveals a pattern of high gene flow in P. ornatus throughout the South-East Asian Archipelago. This lack of genetic structure may be due to the oceanography-driven connectivity of the pelagic lobster larvae between spawning grounds in Papua New Guinea, the Philippines and, possibly, Indonesia. The connectivity cycle necessitates three generations. The lack of genetic structure of P. ornatus population in the South-East Asian archipelago has important implications for the sustainable management of this lobster in that the species within the region needs to be managed as one genetic stock. PMID:25951344

  1. Circulation constrains the evolution of larval development modes and life histories in the coastal ocean.

    PubMed

    Pringle, James M; Byers, James E; Pappalardo, Paula; Wares, John P; Marshall, Dustin

    2014-04-01

    The evolutionary pressures that drive long larval planktonic durations in some coastal marine organisms, while allowing direct development in others, have been vigorously debated. We introduce into the argument the asymmetric dispersal of larvae by coastal currents and find that the strength of the currents helps determine which dispersal strategies are evolutionarily stable. In a spatially and temporally uniform coastal ocean of finite extent, direct development is always evolutionarily stable. For passively drifting larvae, long planktonic durations are stable when the ratio of mean to fluctuating currents is small and the rate at which larvae increase in size in the plankton is greater than the mortality rate (both in units of per time). However, larval behavior that reduces downstream larval dispersal for a given time in plankton will be selected for, consistent with widespread observations of behaviors that reduce dispersal of marine larvae. Larvae with long planktonic durations are shown to be favored not for the additional dispersal they allow, but for the additional fecundity that larval feeding in the plankton enables. We analyzed the spatial distribution of larval life histories in a large database of coastal marine benthic invertebrates and documented a link between ocean circulation and the frequency of planktotrophy in the coastal ocean. The spatial variation in the frequency of species with planktotrophic larvae is largely consistent with our theory; increases in mean currents lead to a decrease in the fraction of species with planktotrophic larvae over a broad range of temperatures. PMID:24933820

  2. Using post-settlement demography to estimate larval survivorship: a coral reef fish example.

    PubMed

    Johnson, D W; Christie, M R; Stallings, C D; Pusack, T J; Hixon, M A

    2015-11-01

    Many species have multi-stage life cycles in which the youngest stages (e.g., larvae) are small, dispersive, and abundant, whereas later stages are sessile or sedentary. Quantifying survival throughout such early stages is critical for understanding dispersal, population dynamics, and life history evolution. However, dispersive stages can be very difficult to sample in situ, and estimates of survival through the entire duration of these stages are typically poor. Here we describe how demographic information from juveniles and adults can be used to estimate survival throughout a dispersive larval stage that was not sampled directly. Using field measurements of demography, we show that detailed information on post-settlement growth, survival, and reproduction can be used to estimate average larval survivorship under the assumption that a typical individual replaces itself over its lifetime. Applying this approach to a common coral reef fish (bicolor damselfish, Stegastes partitus), we estimated average larval survivorship to be 0.108% (95% CI 0.025-0.484). We next compared this demography-based estimate to an expected value derived from published estimates of larval mortality rates. Our estimate of larval survivorship for bicolor damselfish was approximately two orders of magnitude greater than what would be expected if larval mortality of this species followed the average, size-dependent pattern of mortality inferred from a published sample of marine fishes. Our results highlight the importance of understanding mortality during the earliest phases of larval life, which are typically not sampled, as well as the need to understand the details of how larval mortality scales with body size. PMID:26093629

  3. Asymmetric connectivity of spawning aggregations of a commercially important marine fish using a multidisciplinary approach

    PubMed Central

    Jackson, Alexis; Marinone, Silvio Guido; Erisman, Brad; Moreno-Baez, Marcia; Girón-Nava, Alfredo; Pfister, Tad; Aburto-Oropeza, Octavio; Torre, Jorge

    2014-01-01

    Understanding patterns of larval dispersal is key in determining whether no-take marine reserves are self-sustaining, what will be protected inside reserves and where the benefits of reserves will be observed. We followed a multidisciplinary approach that merged detailed descriptions of fishing zones and spawning time at 17 sites distributed in the Midriff Island region of the Gulf of California with a biophysical oceanographic model that simulated larval transport at Pelagic Larval Duration (PLD) 14, 21 and 28 days for the most common and targeted predatory reef fish, (leopard grouper Mycteroperca rosacea). We tested the hypothesis that source–sink larval metapopulation dynamics describing the direction and frequency of larval dispersal according to an oceanographic model can help to explain empirical genetic data. We described modeled metapopulation dynamics using graph theory and employed empirical sequence data from a subset of 11 sites at two mitochondrial genes to verify the model predictions based on patterns of genetic diversity within sites and genetic structure between sites. We employed a population graph describing a network of genetic relationships among sites and contrasted it against modeled networks. While our results failed to explain genetic diversity within sites, they confirmed that ocean models summarized via graph and adjacency distances over modeled networks can explain seemingly chaotic patterns of genetic structure between sites. Empirical and modeled networks showed significant similarities in the clustering coefficients of each site and adjacency matrices between sites. Most of the connectivity patterns observed towards downstream sites (Sonora coast) were strictly asymmetric, while those between upstream sites (Baja and the Midriffs) were symmetric. The best-supported gene flow model and analyses of modularity of the modeled networks confirmed a pulse of larvae from the Baja Peninsula, across the Midriff Island region and towards the

  4. Asymmetric connectivity of spawning aggregations of a commercially important marine fish using a multidisciplinary approach.

    PubMed

    Munguia-Vega, Adrian; Jackson, Alexis; Marinone, Silvio Guido; Erisman, Brad; Moreno-Baez, Marcia; Girón-Nava, Alfredo; Pfister, Tad; Aburto-Oropeza, Octavio; Torre, Jorge

    2014-01-01

    Understanding patterns of larval dispersal is key in determining whether no-take marine reserves are self-sustaining, what will be protected inside reserves and where the benefits of reserves will be observed. We followed a multidisciplinary approach that merged detailed descriptions of fishing zones and spawning time at 17 sites distributed in the Midriff Island region of the Gulf of California with a biophysical oceanographic model that simulated larval transport at Pelagic Larval Duration (PLD) 14, 21 and 28 days for the most common and targeted predatory reef fish, (leopard grouper Mycteroperca rosacea). We tested the hypothesis that source-sink larval metapopulation dynamics describing the direction and frequency of larval dispersal according to an oceanographic model can help to explain empirical genetic data. We described modeled metapopulation dynamics using graph theory and employed empirical sequence data from a subset of 11 sites at two mitochondrial genes to verify the model predictions based on patterns of genetic diversity within sites and genetic structure between sites. We employed a population graph describing a network of genetic relationships among sites and contrasted it against modeled networks. While our results failed to explain genetic diversity within sites, they confirmed that ocean models summarized via graph and adjacency distances over modeled networks can explain seemingly chaotic patterns of genetic structure between sites. Empirical and modeled networks showed significant similarities in the clustering coefficients of each site and adjacency matrices between sites. Most of the connectivity patterns observed towards downstream sites (Sonora coast) were strictly asymmetric, while those between upstream sites (Baja and the Midriffs) were symmetric. The best-supported gene flow model and analyses of modularity of the modeled networks confirmed a pulse of larvae from the Baja Peninsula, across the Midriff Island region and towards the

  5. Understanding the Spatial Scale of Genetic Connectivity at Sea: Unique Insights from a Land Fish and a Meta-Analysis.

    PubMed

    Cooke, Georgina M; Schlub, Timothy E; Sherwin, William B; Ord, Terry J

    2016-01-01

    Quantifying the spatial scale of population connectivity is important for understanding the evolutionary potential of ecologically divergent populations and for designing conservation strategies to preserve those populations. For marine organisms like fish, the spatial scale of connectivity is generally set by a pelagic larval phase. This has complicated past estimates of connectivity because detailed information on larval movements are difficult to obtain. Genetic approaches provide a tractable alternative and have the added benefit of estimating directly the reproductive isolation of populations. In this study, we leveraged empirical estimates of genetic differentiation among populations with simulations and a meta-analysis to provide a general estimate of the spatial scale of genetic connectivity in marine environments. We used neutral genetic markers to first quantify the genetic differentiation of ecologically-isolated adult populations of a land dwelling fish, the Pacific leaping blenny (Alticus arnoldorum), where marine larval dispersal is the only probable means of connectivity among populations. We then compared these estimates to simulations of a range of marine dispersal scenarios and to collated FST and distance data from the literature for marine fish across diverse spatial scales. We found genetic connectivity at sea was extensive among marine populations and in the case of A. arnoldorum, apparently little affected by the presence of ecological barriers. We estimated that ~5000 km (with broad confidence intervals ranging from 810-11,692 km) was the spatial scale at which evolutionarily meaningful barriers to gene flow start to occur at sea, although substantially shorter distances are also possible for some taxa. In general, however, such a large estimate of connectivity has important implications for the evolutionary and conservation potential of many marine fish communities. PMID:27195493

  6. Understanding the Spatial Scale of Genetic Connectivity at Sea: Unique Insights from a Land Fish and a Meta-Analysis

    PubMed Central

    Cooke, Georgina M.; Schlub, Timothy E.; Sherwin, William B.; Ord, Terry J.

    2016-01-01

    Quantifying the spatial scale of population connectivity is important for understanding the evolutionary potential of ecologically divergent populations and for designing conservation strategies to preserve those populations. For marine organisms like fish, the spatial scale of connectivity is generally set by a pelagic larval phase. This has complicated past estimates of connectivity because detailed information on larval movements are difficult to obtain. Genetic approaches provide a tractable alternative and have the added benefit of estimating directly the reproductive isolation of populations. In this study, we leveraged empirical estimates of genetic differentiation among populations with simulations and a meta-analysis to provide a general estimate of the spatial scale of genetic connectivity in marine environments. We used neutral genetic markers to first quantify the genetic differentiation of ecologically-isolated adult populations of a land dwelling fish, the Pacific leaping blenny (Alticus arnoldorum), where marine larval dispersal is the only probable means of connectivity among populations. We then compared these estimates to simulations of a range of marine dispersal scenarios and to collated FST and distance data from the literature for marine fish across diverse spatial scales. We found genetic connectivity at sea was extensive among marine populations and in the case of A. arnoldorum, apparently little affected by the presence of ecological barriers. We estimated that ~5000 km (with broad confidence intervals ranging from 810–11,692 km) was the spatial scale at which evolutionarily meaningful barriers to gene flow start to occur at sea, although substantially shorter distances are also possible for some taxa. In general, however, such a large estimate of connectivity has important implications for the evolutionary and conservation potential of many marine fish communities. PMID:27195493

  7. Drosophila Food-Associated Pheromones: Effect of Experience, Genotype and Antibiotics on Larval Behavior

    PubMed Central

    Thibert, Julien; Farine, Jean-Pierre; Cortot, Jérôme; Ferveur, Jean-François

    2016-01-01

    Animals ubiquitously use chemical signals to communicate many aspects of their social life. These chemical signals often consist of environmental cues mixed with species-specific signals—pheromones—emitted by conspecifics. During their life, insects can use pheromones to aggregate, disperse, choose a mate, or find the most suitable food source on which to lay eggs. Before pupariation, larvae of several Drosophila species migrate to food sources depending on their composition and the presence of pheromones. Some pheromones derive from microbiota gut activity and these food-associated cues can enhance larval attraction or repulsion. To explore the mechanisms underlying the preference (attraction/repulsion) to these cues and clarify their effect, we manipulated factors potentially involved in larval response. In particular, we found that the (i) early exposure to conspecifics, (ii) genotype, and (iii) antibiotic treatment changed D. melanogaster larval behavior. Generally, larvae—tested either individually or in groups—strongly avoided food processed by other larvae. Compared to previous reports on larval attractive pheromones, our data suggest that such attractive effects are largely masked by food-associated compounds eliciting larval aversion. The antagonistic effect of attractive vs. aversive compounds could modulate larval choice of a pupariation site and impact the dispersion of individuals in nature. PMID:26987117

  8. Kinship analyses identify fish dispersal events on a temperate coastline.

    PubMed

    Schunter, C; Pascual, M; Garza, J C; Raventos, N; Macpherson, E

    2014-06-22

    Connectivity is crucial for the persistence and resilience of marine species, the establishment of networks of marine protected areas and the delineation of fishery management units. In the marine environment, understanding connectivity is still a major challenge, due to the technical difficulties of tracking larvae. Recently, parentage analysis has provided a means to address this question effectively. To be effective, this method requires limited adult movement and extensive sampling of parents, which is often not possible for marine species. An alternative approach that is less sensitive to constraints in parental movement and sampling could be the reconstruction of sibships. Here, we directly measure connectivity and larval dispersal in a temperate marine ecosystem through both analytical approaches. We use data from 178 single nucleotide polymorphism markers to perform parentage and sibship reconstruction of the black-faced blenny (Tripterygion delaisi) from an open coastline in the Mediterranean Sea. Parentage analysis revealed a decrease in dispersal success in the focal area over 1 km distance and approximately 6.5% of the juveniles were identified as self-recruits. Sibship reconstruction analysis found that, in general, full siblings did not recruit together to the same location, and that the largest distance between recruitment locations was much higher (11.5 km) than found for parent-offspring pairs (1.2 km). Direct measurements of dispersal are essential to understanding connectivity patterns in different marine habitats, and show the degree of self-replenishment and sustainability of populations of marine organisms. We demonstrate that sibship reconstruction allows direct measurements of dispersal and family structure in marine species while being more easily applied in those species for which the collection of the parental population is difficult or unfeasible. PMID:24812064

  9. Neuroanatomy of pars intercerebralis neurons with special reference to their connections with neurons immunoreactive for pigment-dispersing factor in the blow fly Protophormia terraenovae.

    PubMed

    Yasuyama, Kouji; Hase, Hiroaki; Shiga, Sakiko

    2015-10-01

    Input regions of pars intercerebralis (PI) neurons are examined by confocal and electron microscopies with special reference to their connections with neurons immunoreactive for pigment-dispersing factor (PDF) in the blow fly, Protophormia terraenovae. PI neurons are a prerequisite for ovarian development under long-day conditions. Backfills from the cardiac recurrent nerve after severance of the posterior lateral tracts labeled thin fibers derived from the PI neurons in the superior medial protocerebrum. These PI fibers were mainly synapsin-negative and postsynaptic to unknown varicose profiles containing dense-core vesicles. Backfilled fibers in the periesophageal neuropils, derived from the PI neurons or neurons with somata in the subesophageal zone, were varicose and some were synapsin-positive. Electron microscopy revealed the presence of both presynaptic and postsynaptic sites in backfilled fibers in the periesophageal neuropils. Many PDF-immunoreactive varicosities were found in the superior medial and lateral protocerebrum and double-labeling showed that 60-88 % of PDF-immunoreactive varicosities were also synapsin-immunoreactive. Double-labeling with the backfills and PDF immunocytochemistry showed that the PI fibers and PDF-immunoreactive varicosities were located close to each other in the superior medial protocerebrum. Results of triple-labeling of PI neurons, PDF-immunoreactive neurons and synapsin-immunoreactive terminals demonstrated that the synapsin-positive PDF-immunoreactive varicosities contacted the PI fibers. These data suggest that PI neurons receive synaptic contacts from PDF-immunoreactive fibers, which are derived from circadian clock neurons, of small ventral lateral neurons (previously called OL2) or posterior dorsal (PD) neurons with somata in the pars lateralis. PMID:25971932

  10. Limited genetic connectivity of Pavona gigantea in the Mexican Pacific

    NASA Astrophysics Data System (ADS)

    Saavedra-Sotelo, N. C.; Calderon-Aguilera, L. E.; Reyes-Bonilla, H.; López-Pérez, R. A.; Medina-Rosas, P.; Rocha-Olivares, A.

    2011-09-01

    Coral reefs are the most complex and diverse of aquatic ecosystems. Their vulnerability and deterioration in the face of anthropogenic disturbance require the adoption of conservation and restoration efforts to maintain their resilience, for which connectivity is of paramount importance. Dispersal of meroplanktonic larval stages drives the levels of connectivity among coral populations and is influenced by the local current regime, the synchronization of spawning events, and the capacity of larvae to reach recruitment sites. This research aims to quantify the levels of connectivity among Pavona gigantea populations in the Mexican Pacific, using two mitochondrial genes and a nuclear gene. Mitochondrial genes were insufficiently variable to test geographical heterogeneity, whereas the more variable ( h ≥ 0.86) nuclear rDNA indicated significant geographic differentiation ( Φ ST = 0.159, P < 0.001) among five locations along the Mexican Pacific, but no evidence of isolation by distance. Gene flow was limited among most sampled locales, and the largest estimate suggested moderate and unidirectional gene flow from Huatulco Bays to La Paz Bay and Marietas Islands. We found partial agreement between the patterns of connectivity among localities and the general pattern of superficial oceanographic circulation of the region, particularly in reference with the expected influence of the northward flowing West Mexican Current. These results suggest a limited demographic connectivity among Pavona gigantea populations along the Mexican Pacific, mediated by passive larval transport, and highlight the difficulty of predicting connectivity patterns on the basis of highly variable oceanographic regimes and reproductive events. The limited connectivity is of consequence for the viability and vulnerability of local populations and should be considered in the management and conservation strategies in the region.

  11. Post-settlement dispersal: the neglected link in maintenance of soft-sediment biodiversity.

    PubMed

    Pilditch, Conrad A; Valanko, Sebastian; Norkko, Joanna; Norkko, Alf

    2015-02-01

    Seafloor integrity is threatened by disturbances owing to human activities. The capacity of the system to recover from disturbances, as well as maintain resilience and function, depends on dispersal. In soft-sediment systems, dispersal continues after larval settlement, but there are very few measurements of how far the post-settlers disperse in nature. Spatial scales of post-settlement dispersal are, however, likely to be similar to pelagic larval dispersal because of continued, frequent, small-scale dispersal over longer periods. The consequences of this dispersal may be more important for the maintenance of biodiversity and metacommunity dynamics than is pelagic larval dispersal, because of the greater size and competency of the dispersers. We argue that an increased empirical understanding of post-settlement dispersal processes is key for predicting how benthic communities will respond to local disturbances and shrinking regional species pools, with implications for monitoring, managing and conserving biodiversity. PMID:25652219

  12. Post-settlement dispersal: the neglected link in maintenance of soft-sediment biodiversity

    PubMed Central

    Pilditch, Conrad A.; Valanko, Sebastian; Norkko, Joanna; Norkko, Alf

    2015-01-01

    Seafloor integrity is threatened by disturbances owing to human activities. The capacity of the system to recover from disturbances, as well as maintain resilience and function, depends on dispersal. In soft-sediment systems, dispersal continues after larval settlement, but there are very few measurements of how far the post-settlers disperse in nature. Spatial scales of post-settlement dispersal are, however, likely to be similar to pelagic larval dispersal because of continued, frequent, small-scale dispersal over longer periods. The consequences of this dispersal may be more important for the maintenance of biodiversity and metacommunity dynamics than is pelagic larval dispersal, because of the greater size and competency of the dispersers. We argue that an increased empirical understanding of post-settlement dispersal processes is key for predicting how benthic communities will respond to local disturbances and shrinking regional species pools, with implications for monitoring, managing and conserving biodiversity. PMID:25652219

  13. 'Peer pressure' in larval Drosophila?

    PubMed

    Niewalda, Thomas; Jeske, Ines; Michels, Birgit; Gerber, Bertram

    2014-01-01

    Understanding social behaviour requires a study case that is simple enough to be tractable, yet complex enough to remain interesting. Do larval Drosophila meet these requirements? In a broad sense, this question can refer to effects of the mere presence of other larvae on the behaviour of a target individual. Here we focused in a more strict sense on 'peer pressure', that is on the question of whether the behaviour of a target individual larva is affected by what a surrounding group of larvae is doing. We found that innate olfactory preference of a target individual was neither affected (i) by the level of innate olfactory preference in the surrounding group nor (ii) by the expression of learned olfactory preference in the group. Likewise, learned olfactory preference of a target individual was neither affected (iii) by the level of innate olfactory preference of the surrounding group nor (iv) by the learned olfactory preference the group was expressing. We conclude that larval Drosophila thus do not take note of specifically what surrounding larvae are doing. This implies that in a strict sense, and to the extent tested, there is no social interaction between larvae. These results validate widely used en mass approaches to the behaviour of larval Drosophila. PMID:24907371

  14. The role of internal waves in larval fish interactions with potential predators and prey

    NASA Astrophysics Data System (ADS)

    Greer, Adam T.; Cowen, Robert K.; Guigand, Cedric M.; Hare, Jonathan A.; Tang, Dorothy

    2014-09-01

    Tidally driven internal wave packets in coastal environments have the potential to influence patchiness of larval fishes, prey, and gelatinous predators. We used the In Situ Ichthyoplankton Imaging System (ISIIS) to synoptically sample larval fishes, copepods, and planktonic predators (ctenophores, hydromedusae, chaetognaths, and polychaetes) across these predictable features in the summer near Stellwagen Bank, Massachusetts, USA. Full water column profiles and fixed depth transects (∼10 m depth) were used to quantify vertical and horizontal components of the fish and invertebrate distributions during stable and vertically mixed conditions associated with tidally generated internal waves. Larval fishes, consisting mostly of Urophycis spp., Merluccius bilinearis, and Labridae, were concentrated near the surface, with larger sizes generally occupying greater depths. During stable water column conditions, copepods formed a near surface thin layer several meters above the chlorophyll-a maximum that was absent when internal waves were propagating. In contrast, ctenophores and other predators were much more abundant at depth, but concentrations near 10 m increased immediately after the internal hydraulic jump mixed the water column. During the propagation of internal waves, the fine-scale abundance of larval fishes was more correlated with the abundance of gelatinous predators and less correlated with copepods compared to the stable conditions. Vertical oscillations caused by the internal hydraulic jump can disperse patches of zooplankton and force surface dwelling larval fishes into deeper water where probability of predator contact is increased, creating conditions potentially less favorable for larval fish growth and survival on short time scales.

  15. Measuring thigmotaxis in larval zebrafish.

    PubMed

    Schnörr, S J; Steenbergen, P J; Richardson, M K; Champagne, D L

    2012-03-17

    One of the most commonly used behavioral endpoints measured in preclinical studies using rodent models is thigmotaxis (or "wall-hugging"). Thigmotaxis is a well-validated index of anxiety in animals and humans. While assays measuring thigmotaxis in adult zebrafish have been developed, a thigmotaxis assay has not yet been validated in larval zebrafish. Here we present a novel assay for measurement of thigmotaxis in zebrafish larvae that is triggered by a sudden change in illumination (i.e. sudden light-to-darkness transition) and performed in a standard 24-well plate. We show that zebrafish larvae as young as 5 days post fertilization respond to this challenge by engaging in thigmotaxis. Thigmotaxis was significantly attenuated by anxiolytic (diazepam) and significantly enhanced by anxiogenic (caffeine) drugs, thus representing the first validated thigmotaxis assay for larval zebrafish. We also show that exposure to sudden darkness per se may represent an anxiogenic situation for larval zebrafish since less contrasting light-to-darkness transitions (achieved by lowering darkness degrees) significantly decreased thigmotaxis levels in a manner similar to what was achieved with diazepam. These findings suggest that stimuli such as exposure to sudden darkness could be used proficiently to trigger the expression of anxiety-like behaviors in laboratory settings. In sum, this is a versatile protocol allowing testing of both anxiolytic and anxiogenic drugs in a cost-effective manner (only 10 min). This assay is also amenable to medium to high-throughput capacity while constituting a valuable tool for stress and central nervous system research as well as for preclinical drug screening and discovery. PMID:22197677

  16. Soundscape manipulation enhances larval recruitment of a reef-building mollusk

    PubMed Central

    Bohnenstiehl, DelWayne R.; Eggleston, David B.

    2015-01-01

    Marine seafloor ecosystems, and efforts to restore them, depend critically on the influx and settlement of larvae following their pelagic dispersal period. Larval dispersal and settlement patterns are driven by a combination of physical oceanography and behavioral responses of larvae to a suite of sensory cues both in the water column and at settlement sites. There is growing evidence that the biological and physical sounds associated with adult habitats (i.e., the “soundscape”) influence larval settlement and habitat selection; however, the significance of acoustic cues is rarely tested. Here we show in a field experiment that the free-swimming larvae of an estuarine invertebrate, the eastern oyster, respond to the addition of replayed habitat-related sounds. Oyster larval recruitment was significantly higher on larval collectors exposed to oyster reef sounds compared to no-sound controls. These results provide the first field evidence that soundscape cues may attract the larval settlers of a reef-building estuarine invertebrate. PMID:26056624

  17. Consequences of pre-dispersal damage by insects for the dispersal and recruitment of mangroves.

    PubMed

    Minchinton, Todd E

    2006-05-01

    Herbivores may enhance plant recruitment, but such positive interactions may be overlooked in favour of obvious negative effects of herbivory on propagules. My objective was to determine whether larval insects that feed and develop within fruit of the mangrove Avicennia marina act as mutualist herbivores by increasing the dispersal of propagules without affecting their viability and emerging successfully as adults following dispersal of the propagule by water. Surveys revealed that frugivory is common throughout the mangrove forest, and fruit had up to six exit holes where larvae had emerged as adults. Larval insects did not affect the flotation of propagules with pericarps, a thin structure that provides buoyancy for dispersal by water. In contrast, after simulating germination by removing the pericarp, the majority of propagules with three exit holes floated on average for 20 h longer than those without exit holes, which sank immediately. Based on this evidence that frugivory could increase the dispersal potential of propagules, I predicted that propagules consumed by larval insects should disperse farther than undamaged propagules, and this was tested by quantifying the potential viability of propagules stranded on beaches at increasing distances (up to 20 km) from mangrove forests. Flies and moths emerged as adults after being transported tens of kilometres within mangrove propagules, revealing a novel mode of dispersal. Proportionally fewer potentially viable propagules were supplied to beaches at increasing distances from mangrove forests, however, indicating that larval insects negatively affect recruitment and are thus not acting as mutualist herbivores. Nevertheless, when transported back to the mangrove forest, seedlings established from propagules damaged by larval insects and stranded on beaches. Therefore, although frugivory does not preclude mangrove recruitment, its negative effects in the pre-dispersal environment may be intensified with increasing

  18. Embryogenesis, hatching and larval development of Artemia during orbital spaceflight

    NASA Technical Reports Server (NTRS)

    Spooner, B. S.; Debell, L.; Armbrust, L.; Guikema, J. A.; Metcalf, J.; Paulsen, A.

    1994-01-01

    Developmental biology studies, using gastrula-arrested cysts of the brine shrimp Artemia franciscana, were conducted during two flights of the space shuttle Atlantis (missions STS-37 and STS-43) in 1991. Dehydrated cysts were activated, on orbit, by addition of salt water to the cysts, and then development was terminated by the addition of fixative. Development took place in 5 ml syringes, connected by tubing to activation syringes, containing salt water, and termination syringes, containing fixative. Comparison of space results with simultaneous ground control experiments showed that equivalent percentages of naupliar larvae hatched in the syringes (40%). Thus, reactivation of development, completion of embryogenesis, emergence and hatching took place, during spaceflight, without recognizable alteration in numbers of larvae produced. Post-hatching larval development was studied in experiments where development was terminated, by introduction of fixative, 2 days, 4 days, and 8 days after reinitiation of development. During spaceflight, successive larval instars or stages, interrupted by molts, occurred, generating brine shrimp at appropriate larval instars. Naupliar larvae possessed the single naupliar eye, and development of the lateral pair of adult eyes also took place in space. Transmission electron microscopy revealed extensive differentiation, including skeletal muscle and gut endoderm, as well as the eye tissues. These studies demonstrate the potential value of Artemia for developmental biology studies during spa ceflight, and show that extensive degrees of development can take place in this microgravity environment.

  19. Embryogenesis, hatching and larval development of Artemia during orbital spaceflight

    NASA Astrophysics Data System (ADS)

    Spooner, B. S.; Debell, L.; Armbrust, L.; Guikema, J. A.; Metcalf, J.; Paulsen, A.

    1994-08-01

    Developmental biology studies, using gastrula-arrested cysts of the brine shrimp Artemia franciscana, were conducted during two flights of the space shuttle Atlantis (missions STS-37 and STS-43) in 1991. Dehydrated cysts were activated, on orbit, by addition of salt water to the cysts, and then development was terminated by the addition of fixative. Development took place in 5 ml syringes, connected by tubing to activation syringes, containing salt water, and termination syringes, containing fixative. Comparison of space results with simultaneous ground control experiments showed that equivalent percentages of naupliar larvae hatched in the syringes (40%). Thus, reactivation of development, completion of embryogenesis, emergence and hatching took place, during spaceflight, without recognizable alteration in numbers of larvae produced. Post-hatching larval development was studied in experiments where development was terminated, by intrduction of fixative, 2 days, 4 days, and 8 days after reinitiation of development. During spaceflight, successive larval instars or stages, interrupted by molts, occurred, generating brine shrimp at appropriate larval instars. Naupliar larvae possessed the single naupliar eye, and development of the lateral pair of adult eyes also took place in space. Transmission electron microscopy revealed extensive differentiation, including skeletal muscle and gut endoderm, as well as the eye tissues. These studies demonstrate the potential value of Artemia for developmental biology studies during spaceflight, and show that extensive degress of development can take place in this microgravity environment.

  20. Evaluating the importance of demographic connectivity in a marine metapopulation.

    PubMed

    Carson, Henry S; Cook, Geoffrey S; López-Duarte, Paola C; Levin, Lisa A

    2011-10-01

    Recently researchers have gone to great lengths to measure marine metapopulation connectivity via tagging, genetic, and trace-elemental fingerprinting studies. These empirical estimates of larval dispersal are key to assessing the significance of metapopulation connectivity within a demographic context, but the life-history data required to do this are rarely available. To evaluate the demographic consequences of connectivity we constructed seasonal, size-structured metapopulation matrix models for two species of mytilid mussel in San Diego County, California, USA. The self-recruitment and larval exchange terms were produced from a time series of realized connectivities derived from trace-elemental fingerprinting of larval shells during spring and fall from 2003 to 2008. Both species exhibited a strong seasonal pattern of southward movement of recruits in spring and northward movement in fall. Growth and mortality terms were estimated using mark-recapture data from representative sites for each species and subpopulation, and literature estimates of juvenile mortality. Fecundity terms were estimated using county-wide settlement data from 2006-2008; these data reveal peak reproduction and recruitment in fall for Mytilus californianus, and spring for M. galloprovincialis. Elasticity and life-stage simulation analyses were employed to identify the season- and subpopulation-specific vital rates and connectivity terms to which the metapopulation growth rate (lambda) was most sensitive. For both species, metapopulation growth was most sensitive to proportional changes in adult fecundity, survival and growth of juvenile stages, and population connectivity, in order of importance, but relatively insensitive to adult growth or survival. The metapopulation concept was deemed appropriate for both Mytilus species as exchange between the subpopulations was necessary for subpopulation persistence. However, highest metapopulation growth occurred in years when a greater proportion

  1. Is dispersal neutral?

    PubMed

    Lowe, Winsor H; McPeek, Mark A

    2014-08-01

    Dispersal is difficult to quantify and often treated as purely stochastic and extrinsically controlled. Consequently, there remains uncertainty about how individual traits mediate dispersal and its ecological effects. Addressing this uncertainty is crucial for distinguishing neutral versus non-neutral drivers of community assembly. Neutral theory assumes that dispersal is stochastic and equivalent among species. This assumption can be rejected on principle, but common research approaches tacitly support the 'neutral dispersal' assumption. Theory and empirical evidence that dispersal traits are under selection should be broadly integrated in community-level research, stimulating greater scrutiny of this assumption. A tighter empirical connection between the ecological and evolutionary forces that shape dispersal will enable richer understanding of this fundamental process and its role in community assembly. PMID:24962790

  2. Does mating behaviour affect connectivity in marine fishes? Comparative population genetics of two protogynous groupers (Family Serranidae).

    PubMed

    Portnoy, D S; Hollenbeck, C M; Renshaw, M A; Cummings, N J; Gold, J R

    2013-01-01

    Pelagic larval duration (PLD) has been hypothesized to be the primary predictor of connectivity in marine fishes; however, few studies have examined the effects that adult reproductive behaviour may have on realized dispersal. We assessed gene flow (connectivity) by documenting variation in microsatellites and mitochondrial DNA sequences in two protogynous species of groupers, the aggregate spawning red hind, Epinephelus guttatus, and the single-male, harem-spawning coney, Cephalopholis fulva, to ask whether reproductive strategy affects connectivity. Samples of both species were obtained from waters off three islands (Puerto Rico, St. Thomas and St. Croix) in the Caribbean Sea. Despite the notion that aggregate spawning of red hind may facilitate larval retention, stronger signals of population structure were detected in the harem-spawning coney. Heterogeneity and/or inferred barriers, based on microsatellites, involved St. Croix (red hind and coney) and the west coast of Puerto Rico (coney). Heterogeneity and/or inferred barriers, based on mitochondrial DNA, involved St. Croix (coney only). Genetic divergence in both species was stronger for microsatellites than for mitochondrial DNA, suggesting sex-biased dispersal in both species. Long-term migration rates, based on microsatellites, indicated asymmetric gene flow for both species in the same direction as mean surface currents in the region. Red hind had higher levels of variation in microsatellites and lower levels of variation in mitochondrial DNA. Long-term effective size and effective number of breeders were greater for red hind; estimates of θ(f) , a proxy for long-term effective female size, were the same in both species. Patterns of gene flow in both species appear to stem in part from shared aspects of larval and adult biology, local bathymetry and surface current patterns. Differences in connectivity and levels of genetic variation between the species, however, likely stem from differences in behaviour

  3. Close encounters with eddies: oceanographic features increase growth of larval reef fishes during their journey to the reef.

    PubMed

    Shulzitski, Kathryn; Sponaugle, Su; Hauff, Martha; Walter, Kristen; D'Alessandro, Evan K; Cowen, Robert K

    2015-01-01

    Like most benthic marine organisms, coral reef fishes produce larvae that traverse open ocean waters before settling and metamorphosing into juveniles. Where larvae are transported and how they survive is a central question in marine and fisheries ecology. While there is increasing success in modelling potential larval trajectories, our knowledge of the physical and biological processes contributing to larval survivorship during dispersal remains relatively poor. Mesoscale eddies (MEs) are ubiquitous throughout the world's oceans and their propagation is often accompanied by upwelling and increased productivity. Enhanced production suggests that eddies may serve as important habitat for the larval stages of marine organisms, yet there is a lack of empirical data on the growth rates of larvae associated with these eddies. During three cruises in the Straits of Florida, we sampled larval fishes inside and outside five cyclonic MEs. Otolith microstructure analysis revealed that four of five species of reef fish examined had consistently faster growth inside these eddies. Because increased larval growth often leads to higher survivorship, larvae that encounter MEs during transit are more likely to contribute to reef populations. Successful dispersal in oligotrophic waters may rely on larval encounter with such oceanographic features. PMID:25631227

  4. Close encounters with eddies: oceanographic features increase growth of larval reef fishes during their journey to the reef

    PubMed Central

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

    2015-01-01

    Like most benthic marine organisms, coral reef fishes produce larvae that traverse open ocean waters before settling and metamorphosing into juveniles. Where larvae are transported and how they survive is a central question in marine and fisheries ecology. While there is increasing success in modelling potential larval trajectories, our knowledge of the physical and biological processes contributing to larval survivorship during dispersal remains relatively poor. Mesoscale eddies (MEs) are ubiquitous throughout the world's oceans and their propagation is often accompanied by upwelling and increased productivity. Enhanced production suggests that eddies may serve as important habitat for the larval stages of marine organisms, yet there is a lack of empirical data on the growth rates of larvae associated with these eddies. During three cruises in the Straits of Florida, we sampled larval fishes inside and outside five cyclonic MEs. Otolith microstructure analysis revealed that four of five species of reef fish examined had consistently faster growth inside these eddies. Because increased larval growth often leads to higher survivorship, larvae that encounter MEs during transit are more likely to contribute to reef populations. Successful dispersal in oligotrophic waters may rely on larval encounter with such oceanographic features. PMID:25631227

  5. Low interbasin connectivity in a facultatively diadromous fish: evidence from genetics and otolith chemistry.

    PubMed

    Hughes, Jane M; Schmidt, Daniel J; Macdonald, Jed I; Huey, Joel A; Crook, David A

    2014-03-01

    Southern smelts (Retropinna spp.) in coastal rivers of Australia are facultatively diadromous, with populations potentially containing individuals with diadromous or wholly freshwater life histories. The presence of diadromous individuals is expected to reduce genetic structuring between river basins due to larval dispersal via the sea. We use otolith chemistry to distinguish between diadromous and nondiadromous life histories and population genetics to examine interbasin connectivity resulting from diadromy. Otolith strontium isotope ((87) Sr:(86) Sr) transects identified three main life history patterns: amphidromy, freshwater residency and estuarine/marine residency. Despite the potential for interbasin connectivity via larval mixing in the marine environment, we found unprecedented levels of genetic structure for an amphidromous species. Strong hierarchical structure along putative taxonomic boundaries was detected, along with highly structured populations within groups using microsatellites (FST  = 0.046-0.181), and mtDNA (ΦST  = 0.498-0.816). The presence of strong genetic subdivision, despite the fact that many individuals reside in saline water during their early life history, appears incongruous. However, analysis of multielemental signatures in the otolith cores of diadromous fish revealed strong discrimination between river basins, suggesting that diadromous fish spend their early lives within chemically distinct estuaries rather than the more homogenous marine environment, thus avoiding dispersal and maintaining genetic structure. PMID:24410817

  6. 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

  7. Matching oceanography and genetics at the basin scale. Seascape connectivity of the Mediterranean shore crab in the Adriatic Sea.

    PubMed

    Schiavina, M; Marino, I A M; Zane, L; Melià, P

    2014-11-01

    Investigating the interactions between the physical environment and early life history is crucial to understand the mechanisms that shape the genetic structure of marine populations. Here, we assessed the genetic differentiation in a species with larval dispersal, the Mediterranean shore crab (Carcinus aestuarii) in the Adriatic Sea (central Mediterranean), and we investigated the role of oceanic circulation in shaping population structure. To this end, we screened 11 polymorphic microsatellite loci from 431 individuals collected at eight different sites. We found a weak, yet significant, genetic structure into three major clusters: a northern Adriatic group, a central Adriatic group and one group including samples from southern Adriatic and Ionian seas. Genetic analyses were compared, under a seascape genetics approach, with estimates of potential larval connectivity obtained with a coupled physical-biological model that integrates a water circulation model and a description of biological traits affecting dispersal. The cross-validation of the results of the two approaches supported the view that genetic differentiation reflects an oceanographic subdivision of the Adriatic Sea into three subbasins, with circulation patterns allowing the exchange of larvae through permanent connections linking north Adriatic sites and ephemeral connections like those linking the central Adriatic with northern and southern locations. PMID:25294324

  8. Larval green and white sturgeon swimming performance in relation to water-diversion flows

    PubMed Central

    Verhille, Christine E.; Poletto, Jamilynn B.; Cocherell, Dennis E.; DeCourten, Bethany; Baird, Sarah; Cech, Joseph J.; Fangue, Nann A.

    2014-01-01

    Little is known of the swimming capacities of larval sturgeons, despite global population declines in many species due in part to fragmentation of their spawning and rearing habitats by man-made water-diversion structures. Larval green (Acipenser medirostris) and white sturgeon (Acipenser transmontanus) inhabit the highly altered Sacramento–San Joaquin watershed, making them logical species to examine vulnerability to entrainment by altered water flows. The risk of larval sturgeon entrainment is influenced by the ontogeny of swimming capacity and dispersal timing and their interactions with water-diversion structure operations. Therefore, the aim of this study was to describe and compare the ontogeny and allometry of larval green and white sturgeon swimming capacities until completion of metamorphosis into juveniles. Despite the faster growth rates and eventual larger size of larval white sturgeon, green sturgeon critical swimming velocities remained consistently, though modestly, greater than those of white sturgeon throughout the larval life stage. Although behavioural interactions with water-diversion structures are also important considerations, regarding swimming capacity, Sacramento–San Joaquin sturgeons are most vulnerable to entrainment in February–May, when white sturgeon early larvae are in the middle Sacramento River, and April–May, when green sturgeon early larvae are in the upper river. Green sturgeon migrating downstream to the estuary and bays in October–November are also susceptible to entrainment due to their movements combined with seasonal declines in their swimming capacity. An additional inter-species comparison of the allometric relationship between critical swimming velocities and total length with several sturgeon species found throughout the world suggests a similar ontogeny of swimming capacity with growth. Therefore, although dispersal and behaviour differ among river systems and sturgeon species, similar recommendations are

  9. Factors Regulating Early Life History Dispersal of Atlantic Cod (Gadus morhua) from Coastal Newfoundland

    PubMed Central

    Stanley, Ryan R. E.; deYoung, Brad; Snelgrove, Paul V. R.; Gregory, Robert S.

    2013-01-01

    To understand coastal dispersal dynamics of Atlantic cod (Gadus morhua), we examined spatiotemporal egg and larval abundance patterns in coastal Newfoundland. In recent decades, Smith Sound, Trinity Bay has supported the largest known overwintering spawning aggregation of Atlantic cod in the region. We estimated spawning and dispersal characteristics for the Smith Sound-Trinity Bay system by fitting ichthyoplankton abundance data to environmentally-driven, simplified box models. Results show protracted spawning, with sharply increased egg production in early July, and limited dispersal from the Sound. The model for the entire spawning season indicates egg export from Smith Sound is 13%•day−1 with a net mortality of 27%•day–1. Eggs and larvae are consistently found in western Trinity Bay with little advection from the system. These patterns mirror particle tracking models that suggest residence times of 10–20 days, and circulation models indicating local gyres in Trinity Bay that act in concert with upwelling dynamics to retain eggs and larvae. Our results are among the first quantitative dispersal estimates from Smith Sound, linking this spawning stock to the adjacent coastal waters. These results illustrate the biophysical interplay regulating dispersal and connectivity originating from inshore spawning of coastal northwest Atlantic. PMID:24058707

  10. A Tale of Two Anomalies: Depletion, Dispersion, and the Connection between the Stellar Lithium Spread and Inflated Radii on the Pre-main Sequence

    NASA Astrophysics Data System (ADS)

    Somers, Garrett; Pinsonneault, Marc H.

    2014-07-01

    We investigate lithium depletion in standard stellar models (SSMs) and main sequence (MS) open clusters, and explore the origin of the Li dispersion in young, cool stars of equal mass, age, and composition. We first demonstrate that SSMs accurately predict the Li abundances of solar analogs at the zero-age main sequence (ZAMS) within theoretical uncertainties. We then measure the rate of MS Li depletion by removing the [Fe/H]-dependent ZAMS Li pattern from three well-studied clusters, and comparing the detrended data. MS depletion is found to be mass-dependent, in the sense of more depletion at low mass. A dispersion in Li abundance at fixed T eff is nearly universal, and sets in by ~200 Myr. We discuss mass and age dispersion trends, and the pattern is mixed. We argue that metallicity impacts the ZAMS Li pattern, in agreement with theoretical expectations but contrary to the findings of some previous studies, and suggest Li as a test of cluster metallicity. Finally, we argue that a radius dispersion in stars of fixed mass and age, during the epoch of pre-MS Li destruction, is responsible for the spread in Li abundances and the correlation between rotation and Li in young cool stars, most well known in the Pleiades. We calculate stellar models, inflated to match observed radius anomalies in magnetically active systems, and the resulting range of Li abundances reproduces the observed patterns of young clusters. We discuss ramifications for pre-MS evolutionary tracks and age measurements of young clusters, and suggest an observational test.

  11. A tale of two anomalies: Depletion, dispersion, and the connection between the stellar lithium spread and inflated radii on the pre-main sequence

    SciTech Connect

    Somers, Garrett; Pinsonneault, Marc H. E-mail: pinsono@astronomy.ohio-state.edu

    2014-07-20

    We investigate lithium depletion in standard stellar models (SSMs) and main sequence (MS) open clusters, and explore the origin of the Li dispersion in young, cool stars of equal mass, age, and composition. We first demonstrate that SSMs accurately predict the Li abundances of solar analogs at the zero-age main sequence (ZAMS) within theoretical uncertainties. We then measure the rate of MS Li depletion by removing the [Fe/H]-dependent ZAMS Li pattern from three well-studied clusters, and comparing the detrended data. MS depletion is found to be mass-dependent, in the sense of more depletion at low mass. A dispersion in Li abundance at fixed T{sub eff} is nearly universal, and sets in by ∼200 Myr. We discuss mass and age dispersion trends, and the pattern is mixed. We argue that metallicity impacts the ZAMS Li pattern, in agreement with theoretical expectations but contrary to the findings of some previous studies, and suggest Li as a test of cluster metallicity. Finally, we argue that a radius dispersion in stars of fixed mass and age, during the epoch of pre-MS Li destruction, is responsible for the spread in Li abundances and the correlation between rotation and Li in young cool stars, most well known in the Pleiades. We calculate stellar models, inflated to match observed radius anomalies in magnetically active systems, and the resulting range of Li abundances reproduces the observed patterns of young clusters. We discuss ramifications for pre-MS evolutionary tracks and age measurements of young clusters, and suggest an observational test.

  12. The interplay of adult and larval time constraints shapes species differences in larval life history.

    PubMed

    Mikolajewski, Dirk J; De Block, Marjan; Stoks, Robby

    2015-04-01

    In animals with a complex life cycle, larval life-history plasticity is likely shaped by the interplay of selective factors in both larval and adult stages. A wide interspecific variation in responses to larval time constraints imposed by seasonality has been documented. Few studies have addressed differences among closely related species in the evolutionary trajectories of age and size at metamorphosis and their link with larval growth rate under time constraints. None have considered how species-specific length of the reproductive season affects larval developmental responses to time constraints. We tested in four Coenagrion damselfly species whether species with a longer reproductive season, facing a smaller threat of missing out on reproduction, react less to larval time constraints and pre-winter food shortage by accelerating development rate and growth rate, and therefore pay less physiological costs. All species increased development and growth rates under larval time constraints. The magnitude of this increase negatively correlated across species with the length of the reproductive season. Under larval time constraints, only the species exhibiting the longest reproductive season suffered a delayed emergence and a reduced investment in energy storage, yet also showed an increased immune function. Under a longer reproductive season, evolution may favor compensation for larval constraints after metamorphosis. Growth rate was accelerated after pre-winter food shortage to the same extent across species; effects on age and mass at emergence also did not differ among species. Time constraints associated with the length of the reproductive season may predictably contribute to species differences in their response to time constraints imposed in the larval stage. Our study adds empirical proof that the interplay of selective factors in the larval and adult stages may determine life-history plasticity with regard to larval time constraints. PMID:26230032

  13. Oil dispersants

    SciTech Connect

    Flaherty, L.M.

    1989-01-01

    This book contains papers presented at a symposium of the American Society for Testing and Materials. The topics covered include: The effect of elastomers on the efficiency of oil spill dispersants; planning for dispersant use; field experience with dispersants for oil spills on land; and measurements on natural dispersion.

  14. Foraging characteristics of larval bluegill sunfish and larval longear sunfish in the Kanawha River, West Virginia

    USGS Publications Warehouse

    Rider, S.J.; Margraf, F.J.

    1998-01-01

    We determined spatial and temporal foraging characteristics of larval bluegill sunfish (Lepomis macrochirus) and longear sunfish (Lepomis megalotis) in the upper Kanawha River, West Virginia during the summer of 1989. Stomach contents were examined among habitat types (i.e., main channel, main-channel border, and shoreline habitats) and depth (surface, middle, and bottom). Diet of larval bluegill sunfish was dominated by Chironomidae, temporally and spatially. Chironomidae dominated larval longear sunfish diet in main channel and main-channel border collections from all three depths. However, along the shoreline, larval longear sunfish diet was dominated by Cladocera.

  15. Soundscapes and Larval Settlement: Larval Bivalve Responses to Habitat-Associated Underwater Sounds.

    PubMed

    Eggleston, David B; Lillis, Ashlee; Bohnenstiehl, DelWayne R

    2016-01-01

    We quantified the effects of habitat-associated sounds on the settlement response of two species of bivalves with contrasting habitat preferences: (1) Crassostrea virginicia (oyster), which prefers to settle on other oysters, and (2) Mercenaria mercenaria (clam), which settles on unstructured habitats. Oyster larval settlement in the laboratory was significantly higher when exposed to oyster reef sound compared with either off-reef or no-sound treatments. Clam larval settlement did not vary according to sound treatments. Similar to laboratory results, field experiments showed that oyster larval settlement in "larval housings" suspended above oyster reefs was significantly higher compared with off-reef sites. PMID:26610967

  16. 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

    -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. PMID:26913461

  17. Human mediated transport determines the non-native distribution of a dispersal limited estuarine invertebrate

    EPA Science Inventory

    Sessile invertebrates are common invaders of estuarine ecosystems. To expand their non-native ranges, these invasive taxa must contend with the geographically and ecologically discontinuous nature of estuarine habitats, in many cases without the benefit of highly dispersed larval...

  18. A synthesis of genetic connectivity in deep-sea fauna and implications for marine reserve design.

    PubMed

    Baco, Amy R; Etter, Ron J; Ribeiro, Pedro A; von der Heyden, Sophie; Beerli, Peter; Kinlan, Brian P

    2016-07-01

    With anthropogenic impacts rapidly advancing into deeper waters, there is growing interest in establishing deep-sea marine protected areas (MPAs) or reserves. Reserve design depends on estimates of connectivity and scales of dispersal for the taxa of interest. Deep-sea taxa are hypothesized to disperse greater distances than shallow-water taxa, which implies that reserves would need to be larger in size and networks could be more widely spaced; however, this paradigm has not been tested. We compiled population genetic studies of deep-sea fauna and estimated dispersal distances for 51 studies using a method based on isolation-by-distance slopes. Estimates of dispersal distance ranged from 0.24 km to 2028 km with a geometric mean of 33.2 km and differed in relation to taxonomic and life-history factors as well as several study parameters. Dispersal distances were generally greater for fishes than invertebrates with the Mollusca being the least dispersive sampled phylum. Species that are pelagic as adults were more dispersive than those with sessile or sedentary lifestyles. Benthic species from soft-substrate habitats were generally less dispersive than species from hard substrate, demersal or pelagic habitats. As expected, species with pelagic and/or feeding (planktotrophic) larvae were more dispersive than other larval types. Many of these comparisons were confounded by taxonomic or other life-history differences (e.g. fishes being more dispersive than invertebrates) making any simple interpretation difficult. Our results provide the first rough estimate of the range of dispersal distances in the deep sea and allow comparisons to shallow-water assemblages. Overall, dispersal distances were greater for deeper taxa, although the differences were not large (0.3-0.6 orders of magnitude between means), and imbalanced sampling of shallow and deep taxa complicates any simple interpretation. Our analyses suggest the scales of dispersal and connectivity for reserve design

  19. Connectivity, cycles, and persistence thresholds in metapopulation networks.

    PubMed

    Artzy-Randrup, Yael; Stone, Lewi

    2010-01-01

    Synthesising the relationships between complexity, connectivity, and the stability of large biological systems has been a longstanding fundamental quest in theoretical biology and ecology. With the many exciting developments in modern network theory, interest in these issues has recently come to the forefront in a range of multidisciplinary areas. Here we outline a new theoretical analysis specifically relevant for the study of ecological metapopulations focusing primarily on marine systems, where subpopulations are generally connected via larval dispersal. Our work determines the qualitative and quantitative conditions by which dispersal and network structure control the persistence of a set of age-structured patch populations. Mathematical modelling combined with a graph theoretic analysis demonstrates that persistence depends crucially on the topology of cycles in the dispersal network which tend to enhance the effect of larvae "returning home." Our method clarifies the impact directly due to network structure, but this almost by definition can only be achieved by examining the simplified case in which patches are identical; an assumption that we later relax. The methodology identifies critical migration routes, whose presence are vital to overall stability, and therefore should have high conservation priority. In contrast, "lonely links," or links in the network that do not participate in a cyclical component, have no impact on persistence and thus have low conservation priority. A number of other intriguing criteria for persistence are derived. Our modelling framework reveals new insights regarding the determinants of persistence, stability, and thresholds in complex metapopulations. In particular, while theoretical arguments have, in the past, suggested that increasing connectivity is a destabilizing feature in complex systems, this is not evident in metapopulation networks where connectivity, cycles, coherency, and heterogeneity all tend to enhance

  20. 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

  1. Chemical mediation of coral larval settlement by crustose coralline algae.

    PubMed

    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

  2. Connectivity, neutral theories and the assessment of species vulnerability to global change in temperate estuaries

    NASA Astrophysics Data System (ADS)

    Chust, Guillem; Albaina, Aitor; Aranburu, Aizkorri; Borja, Ángel; Diekmann, Onno E.; Estonba, Andone; Franco, Javier; Garmendia, Joxe M.; Iriondo, Mikel; Muxika, Iñigo; Rendo, Fernando; Rodríguez, J. Germán; Ruiz-Larrañaga, Otsanda; Serrão, Ester A.; Valle, Mireia

    2013-10-01

    One of the main adaptation strategies to global change scenarios, aiming to preserve ecosystem functioning and biodiversity, is to maximize ecosystem resilience. The resilience of a species metapopulation can be improved by facilitating connectivity between local populations, which will prevent demographic stochasticity and inbreeding. This investigation estimated the degree of connectivity among estuarine species along the north-eastern Iberian coast, in order to assess community vulnerability to global change scenarios. To address this objective, two connectivity proxy types have been used based upon genetic and ecological drift processes: 1) DNA markers for the bivalve cockle (Cerastoderma edule) and seagrass Zostera noltei, and 2) the decrease in the number of species shared between two sites with geographic distance. Neutral biodiversity theory predicts that dispersal limitation modulates this decrease, and this has been explored in estuarine plants and macroinvertebrates. Results indicate dispersal limitation for both saltmarsh plants and seagrass beds community and Z. noltei populations; this suggests they are especially vulnerable to expected climate changes on their habitats. In contrast, unstructured spatial pattern found in macroinvertebrate communities and in C. edule genetic populations in the area suggests that estuarine soft-bottom macroinvertebrates with planktonic larval dispersal strategies may have a high resilience capacity to moderate changes within their habitats. Our findings allow environmental managers to prioritize the most vulnerable species and habitats to be restored.

  3. Development and plasticity of the Drosophila larval neuromuscular junction

    PubMed Central

    Menon, Kaushiki P.; Carrillo, Robert A.; Zinn, Kai

    2013-01-01

    The Drosophila larval neuromuscular system is relatively simple, containing only 32 motor neurons in each abdominal hemisegment, and its neuromuscular junctions (NMJs) are large, individually specified, and easy to visualize and record from. NMJ synapses exhibit developmental and functional plasticity while displaying stereotyped connectivity. Drosophila Type I NMJ synapses are glutamatergic, while the vertebrate NMJ uses acetylcholine as its primary neurotransmitter. The larval NMJ synapses use ionotropic glutamate receptors (GluRs) that are homologous to AMPA-type glutamate receptors in the mammalian brain, and they have postsynaptic scaffolds that resemble those found in mammalian postsynaptic densities. These features make the Drosophila neuromuscular system an excellent genetic model for the study of excitatory synapses in the mammalian central nervous system. The first section of the review presents an overview of NMJ development. The second section describes genes that regulate NMJ development, including: 1) genes that positively and negatively regulate growth of the NMJ; 2) genes required for maintenance of NMJ bouton structure; 3) genes that modulate neuronal activity and alter NMJ growth; 4) genes involved in trans-synaptic signaling at the NMJ. The third section describes genes that regulate acute plasticity, focusing on translational regulatory mechanisms. Since this review is intended for a developmental biology audience, it does not cover NMJ electrophysiology in detail, and does not review genes for which mutations produce only electrophysiological but no structural phenotypes. PMID:24014452

  4. Anopheline Larval Habitats Seasonality and Species Distribution: A Prerequisite for Effective Targeted Larval Habitats Control Programmes

    PubMed Central

    Kweka, Eliningaya J.; Zhou, Guofa; Munga, Stephen; Lee, Ming-Chieh; Atieli, Harrysone E.; Nyindo, Mramba; Githeko, Andrew K.; Yan, Guiyun

    2012-01-01

    Background Larval control is of paramount importance in the reduction of malaria vector abundance and subsequent disease transmission reduction. Understanding larval habitat succession and its ecology in different land use managements and cropping systems can give an insight for effective larval source management practices. This study investigated larval habitat succession and ecological parameters which influence larval abundance in malaria epidemic prone areas of western Kenya. Methods and Findings A total of 51 aquatic habitats positive for anopheline larvae were surveyed and visited once a week for a period of 85 weeks in succession. Habitats were selected and identified. Mosquito larval species, physico-chemical parameters, habitat size, grass cover, crop cycle and distance to nearest house were recorded. Polymerase chain reaction revealed that An. gambiae s.l was the most dominant vector species comprised of An.gambiae s.s (77.60%) and An.arabiensis (18.34%), the remaining 4.06% had no amplification by polymerase chain reaction. Physico-chemical parameters and habitat size significantly influenced abundance of An. gambiae s.s (P = 0.024) and An. arabiensis (P = 0.002) larvae. Further, larval species abundance was influenced by crop cycle (P≤0.001), grass cover (P≤0.001), while distance to nearest houses significantly influenced the abundance of mosquito species larvae (r = 0.920;P≤0.001). The number of predator species influenced mosquito larval abundance in different habitat types. Crop weeding significantly influenced with the abundance of An.gambiae s.l (P≤0.001) when preceded with fertilizer application. Significantly higher anopheline larval abundance was recorded in habitats in pasture compared to farmland (P = 0.002). When habitat stability and habitat types were considered, hoof print were the most productive followed by disused goldmines. Conclusion These findings suggest that implementation of effective larval control

  5. Genetic assessment of population structure and connectivity in the threatened Mediterranean coral Astroides calycularis (Scleractinia, Dendrophylliidae) at different spatial scales.

    PubMed

    Casado-Amezúa, P; Goffredo, S; Templado, J; Machordom, A

    2012-08-01

    Understanding dispersal patterns, population structure and connectivity among populations is helpful in the management and conservation of threatened species. Molecular markers are useful tools as indirect estimators of these characteristics. In this study, we assess the population genetic structure of the orange coral Astroides calycularis in the Alboran Sea at local and regional scale, and at three localities outside of this basin. Bayesian clustering methods, traditional F-statistics and D(est) statistics were used to determine the patterns of genetic structure. Likelihood and coalescence approaches were used to infer migration patterns and effective population sizes. The results obtained reveal a high level of connectivity among localities separated by as much as 1 km and moderate levels of genetic differentiation among more distant localities, somewhat corresponding with a stepping-stone model of gene flow and connectivity. These data suggest that connectivity among populations of this coral is mainly driven by the biology of the species, with low dispersal abilities; in addition, hydrodynamic processes, oceanographic fronts and the distribution of rocky substrate along the coastline may influence larval dispersal. PMID:22646530

  6. Modelling larval transport in a axial convergence front

    NASA Astrophysics Data System (ADS)

    Robins, P.

    2010-12-01

    Marine larvae exhibit different vertical swimming behaviours, synchronised by factors such as tidal currents and daylight, in order to aid retention near the parent populations and hence promote production, avoid predation, or to stimulate digestion. This paper explores two types of larval migration in an estuarine axial convergent front which is an important circulatory mechanism in many coastal regions where larvae are concentrated. A parallelised, three-dimensional, ocean model was applied to an idealised estuarine channel which was parameterised from observations of an axial convergent front which occurs in the Conwy Estuary, U.K. (Nunes and Simpson, 1985). The model successfully simulates the bilateral cross-sectional recirculation of an axial convergent front, which has been attributed to lateral density gradients established by the interaction of the lateral shear of the longitudinal currents with the axial salinity gradients. On the flood tide, there is surface axial convergence whereas on the ebb tide, there is (weaker) surface divergence. Further simulations with increased/decreased tidal velocities and with stronger/weaker axial salinity gradients are planned so that the effects of a changing climate on the secondary flow can be understood. Three-dimensional Lagrangian Particle Tracking Models (PTMs) have been developed which use the simulated velocity fields to track larvae in the estuarine channel. The PTMs take into account the vertical migrations of two shellfish species that are commonly found in the Conwy Estuary: (i) tidal migration of the common shore crab (Carcinus maenas) and (ii), diel (daily) migration of the Great scallop (Pecten maximus). These migration behaviours are perhaps the most widespread amongst shellfish larvae and have been compared with passive (drifting) particles in order to assess their relative importance in terms of larval transport. Preliminary results suggest that the net along-estuary dispersal over a typical larval

  7. Stress dependent dispersion relations of acoustic waves travelling on a chain of point masses connected by anharmonic linear and torsional springs

    NASA Astrophysics Data System (ADS)

    Pluta, Mieczysław; Amjad, Umar; Klinghammer, Hermann; Jha, Diwaker; Tarar, Khurram; Grill, Wolfgang

    2012-05-01

    The propagation of a deformation along a flexural beam or plate depends on material properties, geometrical conditions like the beam cross-section, effects of stiffening or softening due to external stress, and last but not least the mode of the wave including its polarization. The time-of-flight (TOF) of acoustic waves is influenced by any of the above listed parameters. This effect is utilized in ultrasonic NDE and structural health monitoring applications. It was shown in earlier publications that the solutions of wave equations for a linear chain model consisting of identical mass points, subject to a direction and distance dependent potential, show the dispersion properties and dependencies on externally applied stress of the lowest longitudinal and transversal plate modes. In the model presented here anharmonic potentials are introduced. The potentials are represented by torsional springs at each mass point and linear springs between them. Dynamic equations are derived, based on interactions with next and second next neighbors. The results obtained with the developed model are compared with experimental observations concerning the reaction of the TOF for the lowest Lamb modes in an aluminum plate under variable in plane stress. The developed models are capable to demonstrate general aspects of the mode and frequency dependence of the acousto-elastic coefficients for the lowest symmetric and antisymmetric Lamb waves. The introduced anharmonicities allow furthermore for a close approximation of the experimental findings.

  8. Neuroblast lineage-specific origin of the neurons of the Drosophila larval olfactory system

    PubMed Central

    Das, Abhijit; Gupta, Tripti; Davla, Sejal; Godino, Laura Lucia Prieto; Diegelmann, Sören; Reddy, O. Venkateswara; VijayRaghavan, K.; Reichert, Heinrich; Lovick, Jennifer; Hartenstein, Volker

    2014-01-01

    The complete neuronal repertoire of the central brain of Drosophila originates from only approximately 100 pairs of neural stem cells, or neuroblasts. Each neuroblast produces a highly stereotyped lineage of neurons which innervate specific compartments of the brain. Neuroblasts undergo two rounds of mitotic activity: embryonic divisions produce lineages of primary neurons that build the larval nervous system; after a brief quiescence, the neuroblasts go through a second round of divisions in larval stage to produce secondary neurons which are integrated into the adult nervous system. Here we investigate the lineages that are associated with the larval antennal lobe, one of the most widely studied neuronal systems in fly. We find that the same five neuroblasts responsible for the adult antennal lobe also produce the antennal lobe of the larval brain. However, there are notable differences in the composition of larval (primary) lineages and their adult (secondary) counterparts. Significantly, in the adult, two lineages (lNB/BAlc and adNB/BAmv3) produce uniglomerular projection neurons connecting the antennal lobe with the mushroom body and lateral horn; another lineage, vNB/BAla1, generates multiglomerular neurons reaching the lateral horn directly. lNB/BAlc, as well as a fourth lineage, vlNB/BAla2, generate a diversity of local interneurons. We describe a fifth, previously unknown lineage, BAlp4, which connects the posterior part of the antennal lobe and the neighboring tritocerebrum (gustatory center) with a higher brain center located adjacent to the mushroom body. In the larva, only one of these lineages, adNB/BAmv3, generates all uniglomerular projection neurons. Also as in the adult, lNB/BAlc and vlNB/BAla2 produce local interneurons which, in terms of diversity in architecture and transmitter expression, resemble their adult counterparts. In addition, lineages lNB/BAlc and vNB/BAla1, as well as the newly described BAlp4, form numerous types of projection

  9. Neuroblast lineage-specific origin of the neurons of the Drosophila larval olfactory system.

    PubMed

    Das, Abhijit; Gupta, Tripti; Davla, Sejal; Prieto-Godino, Lucia L; Diegelmann, Sören; Reddy, O Venkateswara; Raghavan, K Vijay; Reichert, Heinrich; Lovick, Jennifer; Hartenstein, Volker

    2013-01-15

    The complete neuronal repertoire of the central brain of Drosophila originates from only approximately 100 pairs of neural stem cells, or neuroblasts. Each neuroblast produces a highly stereotyped lineage of neurons which innervate specific compartments of the brain. Neuroblasts undergo two rounds of mitotic activity: embryonic divisions produce lineages of primary neurons that build the larval nervous system; after a brief quiescence, the neuroblasts go through a second round of divisions in larval stage to produce secondary neurons which are integrated into the adult nervous system. Here we investigate the lineages that are associated with the larval antennal lobe, one of the most widely studied neuronal systems in fly. We find that the same five neuroblasts responsible for the adult antennal lobe also produce the antennal lobe of the larval brain. However, there are notable differences in the composition of larval (primary) lineages and their adult (secondary) counterparts. Significantly, in the adult, two lineages (lNB/BAlc and adNB/BAmv3) produce uniglomerular projection neurons connecting the antennal lobe with the mushroom body and lateral horn; another lineage, vNB/BAla1, generates multiglomerular neurons reaching the lateral horn directly. lNB/BAlc, as well as a fourth lineage, vlNB/BAla2, generate a diversity of local interneurons. We describe a fifth, previously unknown lineage, BAlp4, which connects the posterior part of the antennal lobe and the neighboring tritocerebrum (gustatory center) with a higher brain center located adjacent to the mushroom body. In the larva, only one of these lineages, adNB/BAmv3, generates all uniglomerular projection neurons. Also as in the adult, lNB/BAlc and vlNB/BAla2 produce local interneurons which, in terms of diversity in architecture and transmitter expression, resemble their adult counterparts. In addition, lineages lNB/BAlc and vNB/BAla1, as well as the newly described BAlp4, form numerous types of projection

  10. 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. PMID:26818771

  11. Soundscapes and Larval Settlement: Characterizing the Stimulus from a Larval Perspective.

    PubMed

    Lillis, Ashlee; Eggleston, David B; Bohnenstiehl, DelWayne R

    2016-01-01

    There is growing evidence that underwater sounds serve as a cue for the larvae of marine organisms to locate suitable settlement habitats; however, the relevant spatiotemporal scales of variability in habitat-related sounds and how this variation scales with larval settlement processes remain largely uncharacterized, particularly in estuarine habitats. Here, we provide an overview of the approaches we have developed to characterize an estuarine soundscape as it relates to larval processes, and a conceptual framework is provided for how habitat-related sounds may influence larval settlement, using oyster reef soundscapes as an example. PMID:26611014

  12. Swimming Speed of Larval Snail Does Not Correlate with Size and Ciliary Beat Frequency

    PubMed Central

    Chan, Kit Yu Karen; Jiang, Houshuo; Padilla, Dianna K.

    2013-01-01

    Many marine invertebrates have planktonic larvae with cilia used for both propulsion and capturing of food particles. Hence, changes in ciliary activity have implications for larval nutrition and ability to navigate the water column, which in turn affect survival and dispersal. Using high-speed high-resolution microvideography, we examined the relationship between swimming speed, velar arrangements, and ciliary beat frequency of freely swimming veliger larvae of the gastropod Crepidula fornicata over the course of larval development. Average swimming speed was greatest 6 days post hatching, suggesting a reduction in swimming speed towards settlement. At a given age, veliger larvae have highly variable speeds (0.8–4 body lengths s−1) that are independent of shell size. Contrary to the hypothesis that an increase in ciliary beat frequency increases work done, and therefore speed, there was no significant correlation between swimming speed and ciliary beat frequency. Instead, there are significant correlations between swimming speed and visible area of the velar lobe, and distance between centroids of velum and larval shell. These observations suggest an alternative hypothesis that, instead of modifying ciliary beat frequency, larval C. fornicata modify swimming through adjustment of velum extension or orientation. The ability to adjust velum position could influence particle capture efficiency and fluid disturbance and help promote survival in the plankton. PMID:24367554

  13. Acidification reduced growth rate but not swimming speed of larval sea urchins

    PubMed Central

    Chan, Kit Yu Karen; García, Eliseba; Dupont, Sam

    2015-01-01

    Swimming behaviors of planktonic larvae impact dispersal and population dynamics of many benthic marine invertebrates. This key ecological function is modulated by larval development dynamics, biomechanics of the resulting morphology, and behavioral choices. Studies on ocean acidification effects on larval stages have yet to address this important interaction between development and swimming under environmentally-relevant flow conditions. Our video motion analysis revealed that pH covering present and future natural variability (pH 8.0, 7.6 and 7.2) did not affect age-specific swimming of larval green urchin Strongylocentrotus droebachiensis in still water nor in shear, despite acidified individuals being significantly smaller in size (reduced growth rate). This maintenance of speed and stability in shear was accompanied by an overall change in size-corrected shape, implying changes in swimming biomechanics. Our observations highlight strong evolutionary pressure to maintain swimming in a varying environment and the plasticity in larval responses to environmental change. PMID:25978405

  14. Adaptation to larval crowding in Drosophila ananassae and Drosophila nasuta nasuta: increased larval competitive ability without increased larval feeding rate.

    PubMed

    Nagarajan, Archana; Natarajan, Sharmila Bharathi; Jayaram, Mohan; Thammanna, Ananda; Chari, Sudarshan; Bose, Joy; Jois, Shreyas V; Joshi, Amitabh

    2016-06-01

    The standard view of adaptation to larval crowding in fruitflies, built on results from 25 years of multiple experimental evolution studies on Drosophila melanogaster, was that enhanced competitive ability evolves primarily through increased larval feeding and foraging rate, and increased larval tolerance to nitrogenous wastes, at the cost of efficiency of food conversion to biomass. These results were at odds from the predictions of classical K-selection theory, notably the expectation that selection at high density should result in the increase of efficiency of conversion of food to biomass, and were better interpreted through the lens of α-selection. We show here that populations of D. ananassae and D. n. nasuta subjected to extreme larval crowding evolve greater competitive ability and pre-adult survivorship at high density, primarily through a combination of reduced larval duration, faster attainment of minimum critical size for pupation, greater time efficiency of food conversion to biomass and increased pupation height, with a relatively small role of increased urea/ammonia tolerance, if at all. This is a very different suite of traits than that seen to evolve under similar selection in D. melanogaster, and seems to be closer to the expectations from the canonical theory of K-selection. We also discuss possible reasons for these differences in results across the three species. Overall, the results reinforce the view that our understanding of the evolution of competitive ability in fruitflies needs to be more nuanced than before, with an appreciation that there may be multiple evolutionary routes through which higher competitive ability can be attained. PMID:27350686

  15. Behavorial assessments of larval zebrafish neurotoxicology

    EPA Science Inventory

    Fishes have long been a popular organism in ecotoxicology research, and are increasingly used in human health research as an alternative animal model for chemical screening. Our laboratory incorporates a zebrafish (Danio rerio) embryo/larval assay to screen chemicals for developm...

  16. Modeled connectivity of Acropora millepora populations from reefs of the Spratly Islands and the greater South China Sea

    NASA Astrophysics Data System (ADS)

    Dorman, Jeffrey G.; Castruccio, Frederic S.; Curchitser, Enrique N.; Kleypas, Joan A.; Powell, Thomas M.

    2016-03-01

    The Spratly Island archipelago is a remote network of coral reefs and islands in the South China Sea that is a likely source of coral larvae to the greater region, but about which little is known. Using a particle-tracking model driven by oceanographic data from the Coral Triangle region, we simulated both spring and fall spawning events of Acropora millepora, a common coral species, over a 46-yr period (1960-2005). Simulated population biology of A. millepora included the acquisition and loss of competency, settlement over appropriate benthic habitat, and mortality based on experimental data. The simulations aimed to provide insights into the connectivity of reefs within the Spratly Islands, the settlement of larvae on reefs of the greater South China Sea, and the potential dispersal range of reef organisms from the Spratly Islands. Results suggest that (1) the Spratly Islands may be a significant source of A. millepora larvae for the Palawan reefs (Philippines) and some of the most isolated reefs of the South China Sea; and (2) the relatively isolated western Spratly Islands have limited source reefs supplying them with larvae and fewer of their larvae successfully settling on other reefs. Examination of particle dispersal without biology (settlement and mortality) suggests that larval connectivity is possible throughout the South China Sea and into the Coral Triangle region. Strong differences in the spring versus fall larval connectivity and dispersal highlight the need for a greater understanding of spawning dynamics of the region. This study confirms that the Spratly Islands are likely an important source of larvae for the South China Sea and Coral Triangle region.

  17. Phylogeography and limited genetic connectivity in the endangered boring giant clam across the Coral Triangle.

    PubMed

    DeBoer, Timery S; Subia, Matthew D; Erdmann, Mark V; Kovitvongsa, Katie; Barber, Paul H

    2008-10-01

    The Coral Triangle is the global center of marine biodiversity; however, its coral reefs are critically threatened. Because of the bipartite life history of many marine species with sedentary adults and dispersive pelagic larvae, designing effective marine protected areas requires an understanding of patterns of larval dispersal and connectivity among geographically discrete populations. We used mtDNA sequence data to examine patterns of genetic connectivity in the boring giant clam (Tridacna crocea) in an effort to guide conservation efforts within the Coral Triangle. We collected an approximately 485 base pair fragment of mtDNA cytochrome c oxidase 1 (CO1) from 414 individuals at 26 sites across Indonesia. Genetic structure was strong between regions (phi(ST)=0.549, p < 0.00001) with 3 strongly supported clades: one restricted to western Sumatra, another distributed across central Indonesia, and a third limited to eastern Indonesia and Papua. Even within the single largest clade, small but significant genetic structure was documented (phi(ST)=0.069, p < 0.00001), which indicates limited gene flow within and among phylogeographic regions. Significant patterns of isolation by distance indicated an average dispersal distance of only 25-50 km, which is far below dispersal predictions of 406-708 km derived from estimates of passive dispersal over 10 days via surface currents. The strong regional genetic structure we found indicates potent limits to genetic and demographic connectivity for this species throughout the Coral Triangle and provides a regional context for conservation planning. The recovery of 3 distinct evolutionarily significant units within a well-studied taxonomic group suggests that biodiversity in this region may be significantly underestimated and that Tridacna taxa may be more endangered than currently recognized. PMID:18637905

  18. Ocular dispersion

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Noojin, Gary D.; Thomas, Robert J.; Stolarski, David J.; Rockwell, Benjamin A.; Welch, Ashley J.

    1999-06-01

    Spectrally resolved white-light interferometry (SRWLI) was used to measure the wavelength dependence of refractive index (i.e., dispersion) for various ocular components. The accuracy of the technique was assessed by measurement of fused silica and water, the refractive indices of which have been measured at several different wavelengths. The dispersion of bovine and rabbit aqueous and vitreous humor was measured from 400 to 1100 nm. Also, the dispersion was measured from 400 to 700 nm for aqueous and vitreous humor extracted from goat and rhesus monkey eyes. For the humors, the dispersion did not deviate significantly from water. In an additional experiment, the dispersion of aqueous and vitreous humor that had aged up to a month was compared to freshly harvested material. No difference was found between the fresh and aged media. An unsuccessful attempt was also made to use the technique for dispersion measurement of bovine cornea and lens. Future refinement may allow measurement of the dispersion of cornea and lens across the entire visible and near-infrared wavelength band. The principles of white- light interferometry including image analysis, measurement accuracy, and limitations of the technique, are discussed. In addition, alternate techniques and previous measurements of ocular dispersion are reviewed.

  19. Biological Recruitment in Buoyancy Driven Coastal Systems: Maintenance of Larval Patches

    NASA Astrophysics Data System (ADS)

    Tilburg, C.; Garvine, R.

    2002-12-01

    A number of fisheries depend on the transport of larvae between estuaries and the coastal ocean. This study focuses on the fate of the blue crab, which spawns in the estuary and uses the coastal ocean as a nursery. Recent studies have yielded conceptual models of the transport of blue crab larvae. Maximum spawning occurs in late July and early August at the mouth of the estuary. Once spawned, blue crab larvae rise to the surface and maintain a surface distribution. They are transported out of the estuary within the buoyant river discharge. Offshore Ekman transport associated with upwelling events transport the larvae out of the coastal current, while the associated upshelf currents advect the larvae back towards the estuary. Onshore Ekman transport associated with downwelling events transport the blue crab larvae back into the estuary. Several studies have shown that blue crab larvae form discrete patches that remain intact throughout their time on the coastal shelf. The persistence of patches, despite the dispersive activity of physical diffusion, suggests an active biological role involving larval swimming. The possibility of horizontal swimming as a mechanism for the persistence of larval patches is examined using a physical circulation model, consisting of an idealized estuary and the adjoining coastal region. This physical model is coupled to a tracer algorithm that incorporates larval swimming. A series of simulations were performed to determine the larval swimming speeds necessary for the persistence of larval patches during transport within a buoyant coastal current and upwelling and downwelling episodes. These simulations as well as the validity of their results are discussed.

  20. The Role of Dopamine in Drosophila Larval Classical Olfactory Conditioning

    PubMed Central

    Han, Kyung-An; Stocker, Reinhard F.; Thum, Andreas S.

    2009-01-01

    Learning and memory is not an attribute of higher animals. Even Drosophila larvae are able to form and recall an association of a given odor with an aversive or appetitive gustatory reinforcer. As the Drosophila larva has turned into a particularly simple model for studying odor processing, a detailed neuronal and functional map of the olfactory pathway is available up to the third order neurons in the mushroom bodies. At this point, a convergence of olfactory processing and gustatory reinforcement is suggested to underlie associative memory formation. The dopaminergic system was shown to be involved in mammalian and insect olfactory conditioning. To analyze the anatomy and function of the larval dopaminergic system, we first characterize dopaminergic neurons immunohistochemically up to the single cell level and subsequent test for the effects of distortions in the dopamine system upon aversive (odor-salt) as well as appetitive (odor-sugar) associative learning. Single cell analysis suggests that dopaminergic neurons do not directly connect gustatory input in the larval suboesophageal ganglion to olfactory information in the mushroom bodies. However, a number of dopaminergic neurons innervate different regions of the brain, including protocerebra, mushroom bodies and suboesophageal ganglion. We found that dopamine receptors are highly enriched in the mushroom bodies and that aversive and appetitive olfactory learning is strongly impaired in dopamine receptor mutants. Genetically interfering with dopaminergic signaling supports this finding, although our data do not exclude on naïve odor and sugar preferences of the larvae. Our data suggest that dopaminergic neurons provide input to different brain regions including protocerebra, suboesophageal ganglion and mushroom bodies by more than one route. We therefore propose that different types of dopaminergic neurons might be involved in different types of signaling necessary for aversive and appetitive olfactory memory

  1. Divergence in parental care, habitat selection and larval life history between two species of Peruvian poison frogs: an experimental analysis.

    PubMed

    Brown, J L; Morales, V; Summers, K

    2008-11-01

    Changes in the nature of the ecological resources exploited by a species can lead to the evolution of novel suites of behaviours. We identified a case in which the transition from large pool use to the use of very small breeding pools in neotropical poison frogs (family Dendrobatidae) is associated with the evolution of a suite of behaviours, including biparental care (from uniparental care) and social monogamy (from promiscuity). We manipulated breeding pool size in order to demonstrate experimentally that breeding habitat selection strategy has evolved in concert with changes in parental care and mating system. We also manipulated intra- and interspecific larval interactions to demonstrate that larval adaptation to the use of very small pools for breeding affected the evolution of larval competition and cannibalism. Our results illustrate the intimate connection between breeding pool ecology, parental care and mating strategies in Peruvian poison frogs. PMID:18811668

  2. Live Cell Imaging of Butterfly Pupal and Larval Wings In Vivo

    PubMed Central

    Ohno, Yoshikazu; Otaki, Joji M.

    2015-01-01

    Butterfly wing color patterns are determined during the late larval and early pupal stages. Characterization of wing epithelial cells at these stages is thus critical to understand how wing structures, including color patterns, are determined. Previously, we successfully recorded real-time in vivo images of developing butterfly wings over time at the tissue level. In this study, we employed similar in vivo fluorescent imaging techniques to visualize developing wing epithelial cells in the late larval and early pupal stages 1 hour post-pupation. Both larval and pupal epithelial cells were rich in mitochondria and intracellular networks of endoplasmic reticulum, suggesting high metabolic activities, likely in preparation for cellular division, polyploidization, and differentiation. Larval epithelial cells in the wing imaginal disk were relatively large horizontally and tightly packed, whereas pupal epithelial cells were smaller and relatively loosely packed. Furthermore, larval cells were flat, whereas pupal cells were vertically elongated as deep as 130 μm. In pupal cells, many endosome-like or autophagosome-like structures were present in the cellular periphery down to approximately 10 μm in depth, and extensive epidermal feet or filopodia-like processes were observed a few micrometers deep from the cellular surface. Cells were clustered or bundled from approximately 50 μm in depth to deeper levels. From 60 μm to 80 μm in depth, horizontal connections between these clusters were observed. The prospective eyespot and marginal focus areas were resistant to fluorescent dyes, likely because of their non-flat cone-like structures with a relatively thick cuticle. These in vivo images provide important information with which to understand processes of epithelial cell differentiation and color pattern determination in butterfly wings. PMID:26107809

  3. ‘Peer pressure’ in larval Drosophila?

    PubMed Central

    Niewalda, Thomas; Jeske, Ines; Michels, Birgit; Gerber, Bertram

    2014-01-01

    ABSTRACT Understanding social behaviour requires a study case that is simple enough to be tractable, yet complex enough to remain interesting. Do larval Drosophila meet these requirements? In a broad sense, this question can refer to effects of the mere presence of other larvae on the behaviour of a target individual. Here we focused in a more strict sense on ‘peer pressure’, that is on the question of whether the behaviour of a target individual larva is affected by what a surrounding group of larvae is doing. We found that innate olfactory preference of a target individual was neither affected (i) by the level of innate olfactory preference in the surrounding group nor (ii) by the expression of learned olfactory preference in the group. Likewise, learned olfactory preference of a target individual was neither affected (iii) by the level of innate olfactory preference of the surrounding group nor (iv) by the learned olfactory preference the group was expressing. We conclude that larval Drosophila thus do not take note of specifically what surrounding larvae are doing. This implies that in a strict sense, and to the extent tested, there is no social interaction between larvae. These results validate widely used en mass approaches to the behaviour of larval Drosophila. PMID:24907371

  4. Detecting critical periods in larval flatfish populations

    NASA Astrophysics Data System (ADS)

    Chambers, R. Christopher; Witting, David A.; Lewis, Stephen J.

    2001-06-01

    We evaluate the time-course of deaths and evidence of periods of increased mortality (i.e., critical periods) in laboratory populations of larval flatfish. First, we make the distinction between age-at-death and abundance-at-time data for fish larvae, the latter being typical in studies of natural populations. Next, we describe an experimental investigation of age- and temperature-dependent mortality in larval winter flounder, Pseudopleuronectes americanus. The survivorship curves of these populations differed significantly in both the magnitude and time-course of mortality among the four water temperatures evaluated (7, 10, 13, and 16°C). Mortality was highest in the cooler temperatures and concentrated in the third quarter of larval life, largely concurrent with settlement of surviving members of the cohort. Among the statistical methods for analysing survival data, the proportional-hazards model with time-varying covariates proved best at capturing the patterns of age-specific mortalities. We conclude that fair appraisals of recruitment hypotheses which are predicated on periods of high, age-specific mortality that vary with environmental conditions (e.g., Hjort's critical period hypothesis) will require: (1) data that are based on age, not time; (2) data that are of higher temporal resolution than commonly available at present and (3) analytical methods that are sensitive to irregularities in survivorship curves. We suggest four research approaches for evaluating critical periods in nature.

  5. Inter-individual stereotypy of the Platynereis larval visual connectome

    PubMed Central

    Randel, Nadine; Shahidi, Réza; Verasztó, Csaba; Bezares-Calderón, Luis A; Schmidt, Steffen; Jékely, Gáspár

    2015-01-01

    Developmental programs have the fidelity to form neural circuits with the same structure and function among individuals of the same species. It is less well understood, however, to what extent entire neural circuits of different individuals are similar. Previously, we reported the neuronal connectome of the visual eye circuit from the head of a Platynereis dumerilii larva (Randel et al., 2014). We now report a full-body serial section transmission electron microscopy (ssTEM) dataset of another larva of the same age, for which we describe the connectome of the visual eyes and the larval eyespots. Anatomical comparisons and quantitative analyses of the two circuits reveal a high inter-individual stereotypy of the cell complement, neuronal projections, and synaptic connectivity, including the left-right asymmetry in the connectivity of some neurons. Our work shows the extent to which the eye circuitry in Platynereis larvae is hard-wired. DOI: http://dx.doi.org/10.7554/eLife.08069.001 PMID:26061864

  6. Effect of benserazid and 6-hydroxydopamine on the development of the last larval instar of the house cricket, Acheta domestica L.

    PubMed

    Rózsa, K S; Chudakova, I V; Hiripi, L

    1986-01-01

    The effect of benserazid and 6-OHDA on the duration of the last larval instar and development of wings with intact corpora allata and following allatectomy on Acheta domestica L. was studied. 6-OHDA failed to alter the duration of the last larval instar in the nymphs with intact corpora allata but prolonged it in the allatectomized crickets. Introduction of 6-OHDA in the second phase of the last larval instar caused a deformation of the wings both in allatectomized and intact crickets. Injection of benserazid to the nymphs of the last larval instar prolonged the duration of this phase only in the presence of the corpora allata. The effect of benserazid can be connected to elimination of central inhibition of the corpora allata involving dopaminergic neurons of the brain. PMID:2869911

  7. Limited connectivity and a phylogeographic break characterize populations of the pink anemonefish, Amphiprion perideraion, in the Indo-Malay Archipelago: inferences from a mitochondrial and microsatellite loci

    PubMed Central

    Dohna, Tina A; Timm, Janne; Hamid, Lemia; Kochzius, Marc

    2015-01-01

    To enhance the understanding of larval dispersal in marine organisms, species with a sedentary adult stage and a pelagic larval phase of known duration constitute ideal candidates, because inferences can be made about the role of larval dispersal in population connectivity. Members of the immensely diverse marine fauna of the Indo-Malay Archipelago are of particular importance in this respect, as biodiversity conservation is becoming a large concern in this region. In this study, the genetic population structure of the pink anemonefish, Amphiprion perideraion, is analyzed by applying 10 microsatellite loci as well as sequences of the mitochondrial control region to also allow for a direct comparison of marker-derived results. Both marker systems detected a strong overall genetic structure (ΦST = 0.096, P < 0.0001; mean Dest = 0.17; FST = 0.015, P < 0.0001) and best supported regional groupings (ΦCT = 0.199 P < 0.0001; FCT = 0.018, P < 0.001) that suggested a differentiation of the Java Sea population from the rest of the archipelago. Differentiation of a New Guinea group was confirmed by both markers, but disagreed over the affinity of populations from west New Guinea. Mitochondrial data suggest higher connectivity among populations with fewer signals of regional substructure than microsatellite data. Considering the homogenizing effect of only a few migrants per generation on genetic differentiation between populations, marker-specific results have important implications for conservation efforts concerning this and similar species. PMID:25937914

  8. Offshore-onshore linkages in the larval life history of sole in the Gulf of Lions (NW-Mediterranean)

    NASA Astrophysics Data System (ADS)

    Morat, Fabien; Letourneur, Yves; Blamart, Dominique; Pécheyran, Christophe; Darnaude, Audrey M.; Harmelin-Vivien, Mireille

    2014-08-01

    Understanding individual dispersion from offshore natal areas to coastal nurseries during pelagic larval life is especially important for the sustainable management of exploited marine fish species. For several years, the hatching period, the larval life duration, the average growth rate and the otolith chemical composition (δ13C, δ18O, Sr:Ca and Ba:Ca) during the larval life were studied for young of the year (YOY) of sole collected in three main nurseries of the Gulf of Lions (GoL) (Thau, Mauguio and Berre). We investigated the spatial variation in the origin of the sole larvae which colonised the nurseries around the GoL, and whether temporal differences in environmental conditions during this life stage affected growth and larval life duration. The hatching period ranges from October to March, depending on year and site. Average ages at metamorphosis varied between 43 and 50 days, with the lowest and highest values consistently found for Mauguio and Berre, respectively. Otolith growth rates ranged between 2.7 and 3.2 μm d-1, with the lowest values in Thau and Mauguio and the highest in Berre. Otolith chemical composition during the larval life also varied, suggesting contrasted larval environmental histories in YOY among nurseries. In fishes from Berre and Mauguio, larval life was more influenced by the Rhône River, showing consistently higher larval Ba:Ca ratios (10/23 μmol mol-1) and lower δ13C (-6.5/-6.1‰) and δ18O values (-1.6/0.1‰) than for Thau (with Ba:Ca ratios < 8 μmol mol-1, δ13C ˜-2.3‰ and δ18O ˜1.5‰). Differences in larval otolith composition were observed for 2004, with higher Ba:Ca and lower δ13C and δ18O values than in the two other years. These differences were explained by changes in composition and chemical signatures of water masses after an exceptional flooding event of the Rhône River in late 2003.

  9. Adult and larval traits as determinants of geographic range size among tropical reef fishes

    PubMed Central

    Luiz, Osmar J.; Allen, Andrew P.; Robertson, D. Ross; Floeter, Sergio R.; Kulbicki, Michel; Vigliola, Laurent; Becheler, Ronan; Madin, Joshua S.

    2013-01-01

    Most marine organisms disperse via ocean currents as larvae, so it is often assumed that larval-stage duration is the primary determinant of geographic range size. However, empirical tests of this relationship have yielded mixed results, and alternative hypotheses have rarely been considered. Here we assess the relative influence of adult and larval-traits on geographic range size using a global dataset encompassing 590 species of tropical reef fishes in 47 families, the largest compilation of such data to date for any marine group. We analyze this database using linear mixed-effect models to control for phylogeny and geographical limits on range size. Our analysis indicates that three adult traits likely to affect the capacity of new colonizers to survive and establish reproductive populations (body size, schooling behavior, and nocturnal activity) are equal or better predictors of geographic range size than pelagic larval duration. We conclude that adult life-history traits that affect the postdispersal persistence of new populations are primary determinants of successful range extension and, consequently, of geographic range size among tropical reef fishes. PMID:24065830

  10. Spawning, fertilization, and larval development of Potamocorbula amurensis (Mollusca: Bivalvia) from San Francisco Bay, California

    USGS Publications Warehouse

    Nicolini, M.H.; Penry, D.L.

    2000-01-01

    In Potamocorbula amurensis time for development to the straight-hinge larval stage is 48 hr at 15??C. Potamocorbula amurensis settles at a shell length of approximately 135 ??m 17 to 19 days after fertilization. Our observations of timing of larval devdlopment in P. amurensis support the hypothesis of earlier workers that its route of initial introduction to San Francisco Bay was as veliger larvae transported in ballast water by trans-Pacific cargo ships. The length of the larval period of P. amurensis relative to water mass residence times in San Francisco Bay suggests that it is sufficient to allow substantial dispersal from North Bay to South Bay populations in concordance with previous observations that genetic differentiation among populations of P. amurensis in San Francisco Bay is low. Potamocorbula amurensis is markedly euryhaline at all stages of development. Spawning and fertilization can occur at salinities from 5 to 25 psu, and eggs and sperms can each tolerance at least a 10-psu step increase or decrease in salinity. Embryos that are 2 hr old can tolerate the same range of salinities from (10 to 30 psu), and by the time they are 24 hr old they can tolerate the same range of salinities (2 to 30 psu) that adult clams can. The ability of P. amurensis larvae to tolerate substantial step changes in salinity suggests a strong potential to survive incomplete oceanic exchanges of ballast water and subsequent discharge into receiving waters across a broad range of salinities.

  11. Larval mortality rates and population dynamics of Lesser Sandeel ( Ammodytes marinus) in the northwestern North Sea

    NASA Astrophysics Data System (ADS)

    Heath, Michael R.; Rasmussen, Jens; Bailey, Martin C.; Dunn, John; Fraser, John; Gallego, Alejandro; Hay, Stephen J.; Inglis, Michelle; Robinson, Susan

    2012-05-01

    Intense fishing of a stock of sandeels ( Ammodytes marinus) on the sand banks off the Firth of Forth, northeast Scotland, during the 1990s led to a decline in catch per unit effort to uneconomic levels and collateral failures of piscivorous seabird breeding success at nearby colonies. A prohibition on fishing in 1999 was followed by a short-term recovery of stock biomass, but then a sustained decline to very low levels of abundance. Demographic survey data show that despite the decline in stock, recruit abundance was maintained implying an increasing larval survival rate, and that the stock decline was not due to recruitment failure. To verify this hypothesis we analysed a 10-year long data set of weekly catches of sandeel larvae at a nearby plankton monitoring site to determine the patterns of larval mortality and dispersal. We found that the loss rate of larvae up to 20 d age decreased over time, corresponding with the trend in survival rate implied by the stock demography data. The pattern of loss rate in relation to hatchling abundance implied that mortality may have been density dependent. Our study rules out increased larval mortality as the primary cause of decline in the sandeel stock.

  12. Energy metabolism during larval development of green and white abalone, Haliotis fulgens and H. sorenseni.

    PubMed

    Moran, Amy L; Manahan, Donal T

    2003-06-01

    An understanding of the biochemical and physiological energetics of lecithotrophic development is useful for interpreting patterns of larval development, dispersal potential, and life-history evolution. This study investigated the metabolic rates and use of biochemical reserves in two species of abalone, Haliotis fulgens (the green abalone) and H. sorenseni (the white abalone). Larvae of H. fulgens utilized triacylglycerol as a primary source of endogenous energy reserves for development ( approximately 50% depletion from egg to metamorphic competence). Amounts of phospholipid remained constant, and protein dropped by about 30%. After embryogenesis, larvae of H. fulgens had oxygen consumption rates of 81.7 +/- 5.9 (SE) pmol larva(-1) h(-1) at 15 degrees C through subsequent development. The loss of biochemical reserves fully met the needs of metabolism, as measured by oxygen consumption. Larvae of H. sorenseni were examined during later larval development and were metabolically and biochemically similar to H. fulgens larvae at a comparable stage. Metabolic rates of both species were very similar to previous data for a congener, H. rufescens, suggesting that larval metabolism and energy utilization may be conserved among closely related species that also share similar developmental morphology and feeding modes. PMID:12807704

  13. The formation of the nervous system during larval development in Triops cancriformis (Bosc) (crustacea, Branchiopoda): An immunohistochemical survey.

    PubMed

    Fritsch, Martin; Richter, Stefan

    2010-12-01

    We provide data of the development of thenervous system during the first five larval stages of Triops cancriformis. We use immunohistochemical labeling (against acetylated α-tubulin, serotonin, histamine, and FMRFamide), confocal laser scanning microscopy analysis, and 3D-reconstruction. The development of the nervous system corresponds with the general anamorphic development in T. cancriformis. In larval stage I (L I), all brain parts (proto-, deuto-, and tritocerebrum), the circumoral connectives, and the mandibular neuromere are already present. Also, the frontal filaments and the developing nauplius eye are already present. However, until stage L III, the nauplius eye only consists of three cups. Throughout larval development, the protocerebral network differentiates into distinct subdivisions. In the postnaupliar region, additional neuromeres and their commissures emerge in an anteroposterior gradient. The larval nervous system in L V consists of a differentiated protocerebrum including a central body, a nauplius eye comprising four cups, a circumoral nerve ring, mandibular- and postnaupliar neuromeres up to the seventh thoracic segment, each featuring an anterior and a posterior commissure, and two parallel connectives. The presence of a protocerebral bridge is questionable. The distribution of neurotransmitters in L I is restricted to the naupliar nervous system. Over the course of the five stages of development, neurotransmitter distribution also follows an anteroposterior gradient. Each neuromere is equipped with two ganglia innervating the locomotional appendages and possesses a specific neurotransmitter distribution pattern. We suggest a correlation between neurotransmitter expression and locomotion. PMID:20938985

  14. Evaluating sampling strategies for larval cisco (Coregonus artedi)

    USGS Publications Warehouse

    Myers, J.T.; Stockwell, J.D.; Yule, D.L.; Black, J.A.

    2008-01-01

    To improve our ability to assess larval cisco (Coregonus artedi) populations in Lake Superior, we conducted a study to compare several sampling strategies. First, we compared density estimates of larval cisco concurrently captured in surface waters with a 2 x 1-m paired neuston net and a 0.5-m (diameter) conical net. Density estimates obtained from the two gear types were not significantly different, suggesting that the conical net is a reasonable alternative to the more cumbersome and costly neuston net. Next, we assessed the effect of tow pattern (sinusoidal versus straight tows) to examine if propeller wash affected larval density. We found no effect of propeller wash on the catchability of larval cisco. Given the availability of global positioning systems, we recommend sampling larval cisco using straight tows to simplify protocols and facilitate straightforward measurements of volume filtered. Finally, we investigated potential trends in larval cisco density estimates by sampling four time periods during the light period of a day at individual sites. Our results indicate no significant trends in larval density estimates during the day. We conclude estimates of larval cisco density across space are not confounded by time at a daily timescale. Well-designed, cost effective surveys of larval cisco abundance will help to further our understanding of this important Great Lakes forage species.

  15. Two Hemocyte Lineages Exist in Silkworm Larval Hematopoietic Organ

    PubMed Central

    Nakahara, Yuichi; Kanamori, Yasushi; Kiuchi, Makoto; Kamimura, Manabu

    2010-01-01

    Background Insects have multiple hemocyte morphotypes with different functions as do vertebrates, however, their hematopoietic lineages are largely unexplored with the exception of Drosophila melanogaster. Methodology/Principal Findings To study the hematopoietic lineage of the silkworm, Bombyx mori, we investigated in vivo and in vitro differentiation of hemocyte precursors in the hematopoietic organ (HPO) into the four mature hemocyte subsets, namely, plasmatocytes, granulocytes, oenocytoids, and spherulocytes. Five days after implantation of enzymatically-dispersed HPO cells from a GFP-expressing transgenic line into the hemocoel of normal larvae, differentiation into plasmatocytes, granulocytes and oenocytoids, but not spherulocytes, was observed. When the HPO cells were cultured in vitro, plasmatocytes appeared rapidly, and oenocytoids possessing prophenol oxidase activity appeared several days later. HPO cells were also able to differentiate into a small number of granulocytes, but not into spherulocytes. When functionally mature plasmatocytes were cultured in vitro, oenocytoids were observed 10 days later. These results suggest that the hemocyte precursors in HPO first differentiate into plasmatocytes, which further change into oenocytoids. Conclusions/Significance From these results, we propose that B. mori hemocytes can be divided into two major lineages, a granulocyte lineage and a plasmatocyte-oenocytoid lineage. The origins of the spherulocytes could not be determined in this study. We construct a model for the hematopoietic lineages at the larval stage of B. mori. PMID:20676370

  16. Drift dynamics of larval pallid sturgeon and shovelnose sturgeon in a natural side channel of the Upper Missouri River, Montana

    USGS Publications Warehouse

    Braaten, P.J.; Fuller, D.B.; Holte, L.D.; Lott, R.D.; Viste, W.; Brandt, T.F.; Legare, R.G.

    2008-01-01

    The drift dynamics of larval shovelnose sturgeon Scaphirhynchus platorynchus (1, 2, 6, and 10 d posthatch [dph]) and pallid sturgeon S. albus (1, 2, 5, 9, 11, and 17 dph) were examined in a natural side channel of the Missouri River to quantify the vertical drift location of larvae in the water column, determine the drift velocity of larvae relative to water velocity, and simulate the cumulative distance (km) drifted by larvae during ontogenetic development. Larvae were released at the side-channel inlet and sampled at points 100, 500, 900, and 1,300 m downstream. Larvae drifted primarily near the riverbed, as 58-79% of recaptured shovelnose sturgeon and 63-89% of recaptured pallid sturgeon were sampled in the lower 0.5 m of the water column. The transition from the drifting to the benthic life stage was initiated at 6 dph (mean length, 15.6 mm) for shovelnose sturgeon and at 11-17 dph (mean length, 18.1-20.3 mm) for pallid sturgeon. Across ages, the drift rates of larval shovelnose sturgeon averaged 0.09-0.16 m/s slower than the mean water column velocity. The drift rates of pallid sturgeon were similar to or slightly slower (0.03-0.07 m/s) than the mean water column velocity for 1-11-dph larvae. Conversely, 17-dph larval pallid sturgeon dispersed downstream at a much slower rate (mean, 0.20 m/s slower than the mean water column velocity) owing to their transition to benthic habitats. Drift simulations indicated that the average larval shovelnose sturgeon may drift from 94 to 250 km and the average larval pallid sturgeon may drift from 245 to 530 km, depending on water velocity. Differences in larval drift dynamics between species provide a possible explanation for differences in recruitment between shovelnose sturgeon and pallid sturgeon in the upper Missouri River. ?? Copyright by the American Fisheries Society 2008.

  17. Connectivity of Marine Protected Areas and Its Relation with Total Kinetic Energy.

    PubMed

    D'Agostini, Andressa; Gherardi, Douglas Francisco Marcolino; Pezzi, Luciano Ponzi

    2015-01-01

    The East Continental Shelf (ECS) of Brazil is a hotspot of endemism and biodiversity of reef biota in the South Atlantic, hosting a number of Marine Protected Areas (MPAs). Connectivity of MPAs through larval dispersal influences recruitment, population dynamics, genetic structure and biogeography in coral reef ecosystems. Connectivity of protected reef ecosystem in the ECS was investigated with a hydrodynamic model (ROMS) forcing an Individual Based Model (IBM-Ichthyop), and used groupers (genus Mycteroperca) as functional group. The hydrodynamic output from ROMS was compared with satellite data and showed good agreement with observed surface fields. Eggs were released, in IBM experiments, from April to September along six years (2002-2007) in five MPAs along the ECS. Intrannual variability in recruitment and self-recruitment of grouper larvae was observed, as well as a negative correlation of these population parameters with total Kinetic Energy (KE) used as a metric of the physical environment. Higher KE leads to increased offshore advection of larvae, reduced total recruitment and connectivity of MPAs. Our results indicate high and uni-directional connectivity between MPAs from north to south influenced by the Brazil Current flowing in the same direction. Results also showed that some MPAs act predominantly as "sink" while others are mainly "source" areas. PMID:26448650

  18. Connectivity of Marine Protected Areas and Its Relation with Total Kinetic Energy

    PubMed Central

    D’Agostini, Andressa; Gherardi, Douglas Francisco Marcolino; Pezzi, Luciano Ponzi

    2015-01-01

    The East Continental Shelf (ECS) of Brazil is a hotspot of endemism and biodiversity of reef biota in the South Atlantic, hosting a number of Marine Protected Areas (MPAs). Connectivity of MPAs through larval dispersal influences recruitment, population dynamics, genetic structure and biogeography in coral reef ecosystems. Connectivity of protected reef ecosystem in the ECS was investigated with a hydrodynamic model (ROMS) forcing an Individual Based Model (IBM—Ichthyop), and used groupers (genus Mycteroperca) as functional group. The hydrodynamic output from ROMS was compared with satellite data and showed good agreement with observed surface fields. Eggs were released, in IBM experiments, from April to September along six years (2002–2007) in five MPAs along the ECS. Intrannual variability in recruitment and self-recruitment of grouper larvae was observed, as well as a negative correlation of these population parameters with total Kinetic Energy (KE) used as a metric of the physical environment. Higher KE leads to increased offshore advection of larvae, reduced total recruitment and connectivity of MPAs. Our results indicate high and uni-directional connectivity between MPAs from north to south influenced by the Brazil Current flowing in the same direction. Results also showed that some MPAs act predominantly as “sink” while others are mainly “source” areas. PMID:26448650

  19. Dispersion Modeling.

    ERIC Educational Resources Information Center

    Budiansky, Stephen

    1980-01-01

    This article discusses the need for more accurate and complete input data and field verification of the various models of air pollutant dispension. Consideration should be given to changing the form of air quality standards based on enhanced dispersion modeling techniques. (Author/RE)

  20. Differential patterns of divergence in ocean drifters: Implications for larval flatfish advection and recruitment

    NASA Astrophysics Data System (ADS)

    Wilderbuer, Thomas; Duffy-Anderson, Janet T.; Stabeno, Phyllis; Hermann, Albert

    2016-05-01

    In an effort to better understand the physics of the eastern Bering Sea shelf current as it relates to flatfish advection to favorable near-shore areas, sets of multiple, satellite-tracked, oceanic drifters were released in 2010, 2012 and 2013. The release sites and dates were chosen to coincide with known spawning locations for northern rock sole (Lepidopsetta polyxystra) and known time of larval emergence. The drifters were drogued 5-each at 20 and 40 m in 2010 and 2012, and 4 at 40 m and 2 at 20 m in 2013. The locations of drifters were used to calculate divergence over a 90-day period that corresponds to the larval pelagic duration of Bering Sea shelf northern rock sole. Results indicate that there are alternating periods of positive and negative divergence with an overall trend toward drifter separation after 90 days, roughly the end of the rock sole planktonic larval period. Examination of the drifter behavior at the hourly scale indicates that semi-daily tidal forcing is the primary mechanism of drifter divergence and convergence. Field observations of early-stage northern rock sole larval distributions over the same period indicate that predominant oceanographic advection is northerly over the continental shelf among preflexion stages, though juveniles are predominantly found in nursery areas located ~ 400 km eastward and inshore. Evidence from drifter deployments suggests that behavioral movements during the postflexion and early juvenile larval phases that optimize eastward periodicity of tidal cycles is a viable mechanism to enhance eastward movement of northern rock sole larvae to favorable nursery grounds. A regional ocean modeling system (ROMS) was implemented to track the different rates of dispersion in simulations both with and without tidal forcing, and was used to estimate effective horizontal eddy diffusion in the case of both isobaric (fixed-depth) and Lagrangian (neutrally buoyant) particles. The addition of tidal forcing had a pronounced

  1. Ontogenetic changes in larval swimming and orientation of pre-competent sea urchin Arbacia punctulata in turbulence

    PubMed Central

    Wheeler, Jeanette D.; Chan, Kit Yu Karen; Anderson, Erik J.; Mullineaux, Lauren S.

    2016-01-01

    ABSTRACT Many marine organisms have complex life histories, having sessile adults and relying on the planktonic larvae for dispersal. Larvae swim and disperse in a complex fluid environment and the effect of ambient flow on larval behavior could in turn impact their survival and transport. However, to date, most studies on larvae–flow interactions have focused on competent larvae near settlement. We examined the importance of flow on early larval stages by studying how local flow and ontogeny influence swimming behavior in pre-competent larval sea urchins, Arbacia punctulata. We exposed larval urchins to grid-stirred turbulence and recorded their behavior at two stages (4- and 6-armed plutei) in three turbulence regimes. Using particle image velocimetry to quantify and subtract local flow, we tested the hypothesis that larvae respond to turbulence by increasing swimming speed, and that the increase varies with ontogeny. Swimming speed increased with turbulence for both 4- and 6-armed larvae, but their responses differed in terms of vertical swimming velocity. 4-Armed larvae swam most strongly upward in the unforced flow regime, while 6-armed larvae swam most strongly upward in weakly forced flow. Increased turbulence intensity also decreased the relative time that larvae spent in their typical upright orientation. 6-Armed larvae were tilted more frequently in turbulence compared with 4-armed larvae. This observation suggests that as larvae increase in size and add pairs of arms, they are more likely to be passively re-oriented by moving water, rather than being stabilized (by mechanisms associated with increased mass), potentially leading to differential transport. The positive relationship between swimming speed and larval orientation angle suggests that there was also an active response to tilting in turbulence. Our results highlight the importance of turbulence to planktonic larvae, not just during settlement but also in earlier stages through morphology

  2. Ontogenetic changes in larval swimming and orientation of pre-competent sea urchin Arbacia punctulata in turbulence.

    PubMed

    Wheeler, Jeanette D; Chan, Kit Yu Karen; Anderson, Erik J; Mullineaux, Lauren S

    2016-05-01

    Many marine organisms have complex life histories, having sessile adults and relying on the planktonic larvae for dispersal. Larvae swim and disperse in a complex fluid environment and the effect of ambient flow on larval behavior could in turn impact their survival and transport. However, to date, most studies on larvae-flow interactions have focused on competent larvae near settlement. We examined the importance of flow on early larval stages by studying how local flow and ontogeny influence swimming behavior in pre-competent larval sea urchins, Arbacia punctulata We exposed larval urchins to grid-stirred turbulence and recorded their behavior at two stages (4- and 6-armed plutei) in three turbulence regimes. Using particle image velocimetry to quantify and subtract local flow, we tested the hypothesis that larvae respond to turbulence by increasing swimming speed, and that the increase varies with ontogeny. Swimming speed increased with turbulence for both 4- and 6-armed larvae, but their responses differed in terms of vertical swimming velocity. 4-Armed larvae swam most strongly upward in the unforced flow regime, while 6-armed larvae swam most strongly upward in weakly forced flow. Increased turbulence intensity also decreased the relative time that larvae spent in their typical upright orientation. 6-Armed larvae were tilted more frequently in turbulence compared with 4-armed larvae. This observation suggests that as larvae increase in size and add pairs of arms, they are more likely to be passively re-oriented by moving water, rather than being stabilized (by mechanisms associated with increased mass), potentially leading to differential transport. The positive relationship between swimming speed and larval orientation angle suggests that there was also an active response to tilting in turbulence. Our results highlight the importance of turbulence to planktonic larvae, not just during settlement but also in earlier stages through morphology-flow interactions

  3. Maternal diet and larval diet influence survival skills of larval red drum Sciaenops ocellatus.

    PubMed

    Perez, K O; Fuiman, L A

    2015-04-01

    Larval red drum Sciaenops ocellatus survival, turning rate, routine swimming speed, escape response latency and escape response distance were significantly correlated with essential fatty-acid (EFA) concentrations in eggs. Of the five traits that varied with egg EFA content, two (escape response latency and routine swimming speed) were significantly different when larvae were fed enriched diets compared with the low fatty-acid diet, indicating that the larval diet can compensate for some imbalances in egg composition. Turning rate during routine swimming and escape response distance, however, did not change when larvae predicted to have low performance (based on egg composition) were fed an enriched diet, indicating that these effects of egg composition may be irreversible. Escape response distances and survival rates of larvae predicted to perform well (based on egg composition) and fed highly enriched diets were lower than expected, suggesting that high levels of EFA intake can be detrimental. Altogether, these results suggest that both maternal diet, which is responsible for egg EFA composition, and larval diet may play a role in larval survivorship and recruitment. PMID:25740661

  4. Burrowing activities of the larval lamprey

    USGS Publications Warehouse

    Sawyer, Philip J.

    1959-01-01

    Since the appearance in 1950 of Applegate's work on the sea lamprey in Michigan (U. S. Fish and Wildl. Serv., Spec. Sci. Rept.; Fish, No. 55) and the subsequent development of means to control lampreys in the Great Lakes, biologists have accumulated much additional information on adult lampreys. Larval lampreys, however, are difficult animals to observe in the field, and many facets of their behavior are still unknown. While working with the U. S. Fish and Wildlife Service, I kept ammocetes in captivity, and was able to observe their burrowing activities.

  5. Fog dispersion

    NASA Technical Reports Server (NTRS)

    Frost, W.; Christensen, L. S.; Collins, F. G.; Camp, D. W.

    1980-01-01

    A study of economically viable techniques for dispersing warm fog at commercial airports is presented. Five fog dispersion techniques are examined: evaporation suppression, downwash, mixing, seeding with hygroscopic material, thermal techniques, and charged particle techniques. Thermal techniques, although effective, were found to be too expensive for routine airport operations, and detrimental to the environment. Seeding or helicopter downwash are practical for small-scale or temporary fog clearing, but are probably not useful for airport operations on a routine basis. Considerable disagreement exists on the capability of charged particle techniques, which stems from the fact that different assumptions and parameter values are used in the analytical models. Recommendations resulting from the review of this technique are listed, and include: experimental measurements of the parameters in question; a study to ascertain possible safety hazards, such as increased electrical activity or fuel ignition during refueling operations which could render charged particle techniques impractical; and a study of a single charged particle generator.

  6. Microscopic identification of novel cell types in the integument of larval lake sturgeon, Acipenser fulvescens.

    PubMed

    Shute, Lauren; Huebner, Erwin; Anderson, W Gary

    2016-01-01

    Osmoregulation, respiration, nutrient/mineral transport, and defense mechanisms are all evident in the integument of fish. The role of the integument in these physiological processes is particularly important during early life history in larval fishes, as functional systems such as the gills and gastrointestinal tract are not fully developed. Using a variety of microscopy techniques, we describe the morphology of keratinocytes, mitochondria rich cells, ciliated cells and mucous cells of the skin, yolk sac, and gills. The cytology we observed was similar to previous studies describing the integument of larval fish, however, we have also identified two novel cell types on the integument of larval Lake Sturgeon, Acipenser fulvescens, between 9 and 34 days post fertilization. Our detailed analysis included a multifaceted microscopy approach using scanning electron, transmission electron, and light microscopy to elucidate the histology of the tissue and cellular morphology in addition to quantification and distribution of these novel cell types. The first cell type had a characteristic ampullary shape with a central cavity and a pore opening at the surface. The second, located on the free surface of the epidermis, had an uneven plasma membrane surface. Based on the abundance of secretory vesicles, organelles necessary for protein synthesis, and the lack of neural connection in both cell types, we propose these cells to be involved in the release of semiochemicals that may act as a pheromone, alarm substance, or chemical defense mechanism. PMID:26440535

  7. Apical organs in echinoderm larvae: insights into larval evolution in the Ambulacraria.

    PubMed

    Byrne, Maria; Nakajima, Yoko; Chee, Francis C; Burke, Robert D

    2007-01-01

    The anatomy and cellular organization of serotonergic neurons in the echinoderm apical organ exhibits class-specific features in dipleurula-type (auricularia, bipinnaria) and pluteus-type (ophiopluteus, echinopluteus) larvae. The apical organ forms in association with anterior ciliary structures. Apical organs in dipleurula-type larvae are more similar to each other than to those in either of the pluteus forms. In asteroid bipinnaria and holothuroid auricularia the apical organ spans ciliary band sectors that traverse the anterior-most end of the larvae. The asteroid apical organ also has prominent bilateral ganglia that connect with an apical network of neurites. The simple apical organ of the auricularia is similar to that in the hemichordate tornaria larva. Apical organs in pluteus forms differ markedly. The echinopluteus apical organ is a single structure on the oral hood between the larval arms comprised of two groups of cells joined by a commissure and its cell bodies do not reside in the ciliary band. Ophioplutei have a pair of lateral ganglia associated with the ciliary band of larval arms that may be the ophiuroid apical organ. Comparative anatomy of the serotonergic nervous systems in the dipleurula-type larvae of the Ambulacraria (Echinodermata+Hemichordata) suggests that the apical organ of this deuterostome clade originated as a simple bilaterally symmetric nerve plexus spanning ciliary band sectors at the anterior end of the larva. From this structure, the apical organ has been independently modified in association with the evolution of class-specific larval forms. PMID:17845515

  8. Whole-central nervous system functional imaging in larval Drosophila

    PubMed Central

    Lemon, William C.; Pulver, Stefan R.; Höckendorf, Burkhard; McDole, Katie; Branson, Kristin; Freeman, Jeremy; Keller, Philipp J.

    2015-01-01

    Understanding how the brain works in tight concert with the rest of the central nervous system (CNS) hinges upon knowledge of coordinated activity patterns across the whole CNS. We present a method for measuring activity in an entire, non-transparent CNS with high spatiotemporal resolution. We combine a light-sheet microscope capable of simultaneous multi-view imaging at volumetric speeds 25-fold faster than the state-of-the-art, a whole-CNS imaging assay for the isolated Drosophila larval CNS and a computational framework for analysing multi-view, whole-CNS calcium imaging data. We image both brain and ventral nerve cord, covering the entire CNS at 2 or 5 Hz with two- or one-photon excitation, respectively. By mapping network activity during fictive behaviours and quantitatively comparing high-resolution whole-CNS activity maps across individuals, we predict functional connections between CNS regions and reveal neurons in the brain that identify type and temporal state of motor programs executed in the ventral nerve cord. PMID:26263051

  9. Protective immune responses of the jird to larval Dipetalonema viteae.

    PubMed Central

    Abraham, D; Weiner, D J; Farrell, J P

    1986-01-01

    In vivo and in vitro experiments were performed to study immune protective mechanisms against larval Dipetalonema viteae. Jirds infected with 30 third-stage larvae (L3) of D. viteae for 1, 3 or 5 weeks showed significant killing of challenge larvae implanted for 2 weeks in diffusion chambers. A retardation of larval growth was seen 7 days after larval implantation, and larval death was observed beginning at 10 days. When L3 were placed in vitro with peritoneal exudate cells (PEC) from normal jirds, cellular adherence was seen starting on Day 4, and larval death was seen on Day 10. It was concluded that larvae had to undergo some development in vitro, that would allow cellular adherence to larval surface. Larvae, recovered after 7 days in vivo or in vitro, were placed in culture with normal PEC; cell adherence and worm death occurred at equal rates for both groups of worms. Larvae which had been in culture for 7 days were implanted in immunized jirds for 7 days. Significant killing of these worms was observed, whereas larvae recovered from ticks prior to implantation were not killed. In vivo and in vitro results therefore show that larval development is required for generating susceptibility to specific and/or non-specific immune reactions. A hypothesis is suggested for the function of larval retardation. PMID:3943876

  10. NON-INVASIVE NEUROTOXICITY ASSAY USING LARVAL MEDAKA

    EPA Science Inventory

    We present a method for non-invasive electrophysiological analysis of rapid escape responses in intact, freely behaving larval medaka (Oryzias latipes) before and after short-term exposure to environmental toxicants. ecordings are obtained as a larval medaka swims in a small cham...

  11. EFFECTS OF DIET ON GROWTH AND SURVIVAL OF LARVAL WALLYES

    EPA Science Inventory

    The effects of diet quality on larval walleye (Stizostedion vitreum vitreum) growth and survival are described. The cyclopoid copepod Diacyclops thomasi consumed larval walleyes within 10 min at dense copepod concentrations and within 1 day at lower densities (500 organisms/L). A...

  12. Larval fish distribution in the St. Louis River estuary

    EPA Science Inventory

    Our objective was to determine what study design, environmental, and habitat variables contribute to the distribution and abundance of larval fish in the St. Louis River estuary. Larval fish habitat associations are poorly understood in Great Lakes coastal wetlands, yet critical ...

  13. Adsorption and removal of graphene dispersants.

    PubMed

    Irin, Fahmida; Hansen, Matthew J; Bari, Rozana; Parviz, Dorsa; Metzler, Shane D; Bhattacharia, Sanjoy K; Green, Micah J

    2015-05-15

    We demonstrate three different techniques (dialysis, vacuum filtration, and spray drying) for removal of dispersants from liquid-exfoliated graphene. We evaluate these techniques for elimination of dispersants from both the bulk liquid phase and from the graphene surface. Thermogravimetric analysis (TGA) confirms dispersant removal by these treatments. Vacuum filtration (driving by convective mass transfer) is the most effective method of dispersant removal, regardless of the type of dispersant, removing up to ∼95 wt.% of the polymeric dispersant with only ∼7.4 wt.% decrease in graphene content. Dialysis also removes a significant fraction (∼70 wt.% for polymeric dispersants) of un-adsorbed dispersants without disturbing the dispersion quality. Spray drying produces re-dispersible, crumpled powder samples and eliminates much of the unabsorbed dispersants. We also show that there is no rapid desorption of dispersants from the graphene surface. In addition, electrical conductivity measurements demonstrate conductivities one order of magnitude lower for graphene drop-cast films (where excess dispersants are present) than for vacuum filtered films, confirming poor inter-sheet connectivity when excess dispersants are present. PMID:25681785

  14. Similarities and Differences for Swimming in Larval and Adult Lampreys.

    PubMed

    McClellan, Andrew D; Pale, Timothée; Messina, J Alex; Buso, Scott; Shebib, Ahmad

    2016-01-01

    The spinal locomotor networks controlling swimming behavior in larval and adult lampreys may have some important differences. As an initial step in comparing the locomotor systems in lampreys, in larval animals the relative timing of locomotor movements and muscle burst activity were determined and compared to those previously published for adults. In addition, the kinematics for free swimming in larval and adult lampreys was compared in detail for the first time. First, for swimming in larval animals, the neuromechanical phase lag between the onsets or terminations of muscle burst activity and maximum concave curvature of the body increased with increasing distance along the body, similar to that previously shown in adults. Second, in larval lampreys, but not adults, absolute swimming speed (U; mm s(-1)) increased with animal length (L). In contrast, normalized swimming speed (U'; body lengths [bl] s(-1)) did not increase with L in larval or adult animals. In both larval and adult lampreys, U' and normalized wave speed (V') increased with increasing tail-beat frequency. Wavelength and mechanical phase lag did not vary significantly with tail-beat frequency but were significantly different in larval and adult animals. Swimming in larval animals was characterized by a smaller U/V ratio, Froude efficiency, and Strouhal number than in adults, suggesting less efficient swimming for larval animals. In addition, during swimming in larval lampreys, normalized lateral head movements were larger and normalized lateral tail movements were smaller than for adults. Finally, larval animals had proportionally smaller lateral surface areas of the caudal body and fin areas than adults. These differences are well suited for larval sea lampreys that spend most of the time buried in mud/sand, in which swimming efficiency is not critical, compared to adults that would experience significant selection pressure to evolve higher-efficiency swimming to catch up to and attach to fish for

  15. Otolith geochemistry does not reflect dispersal history of clownfish larvae

    NASA Astrophysics Data System (ADS)

    Berumen, M. L.; Walsh, H. J.; Raventos, N.; Planes, S.; Jones, G. P.; Starczak, V.; Thorrold, S. R.

    2010-12-01

    Natural geochemical signatures in calcified structures are commonly employed to retrospectively estimate dispersal pathways of larval fish and invertebrates. However, the accuracy of the approach is generally untested due to the absence of individuals with known dispersal histories. We used genetic parentage analysis (genotyping) to divide 110 new recruits of the orange clownfish, Amphiprion percula, from Kimbe Island, Papua New Guinea, into two groups: “self-recruiters” spawned by parents on Kimbe Island and “immigrants” that had dispersed from distant reefs (>10 km away). Analysis of daily increments in sagittal otoliths found no significant difference in PLDs or otolith growth rates between self-recruiting and immigrant larvae. We also quantified otolith Sr/Ca and Ba/Ca ratios during the larval phase using laser ablation inductively coupled plasma mass spectrometry. Again, we found no significant differences in larval profiles of either element between self-recruits and immigrants. Our results highlight the need for caution when interpreting otolith dispersal histories based on natural geochemical tags in the absence of water chemistry data or known-origin larvae with which to test the discriminatory ability of natural tags.

  16. Lost at sea: ocean acidification undermines larval fish orientation via altered hearing and marine soundscape modification.

    PubMed

    Rossi, Tullio; Nagelkerken, Ivan; Pistevos, Jennifer C A; Connell, Sean D

    2016-01-01

    The dispersal of larvae and their settlement to suitable habitat is fundamental to the replenishment of marine populations and the communities in which they live. Sound plays an important role in this process because for larvae of various species, it acts as an orientational cue towards suitable settlement habitat. Because marine sounds are largely of biological origin, they not only carry information about the location of potential habitat, but also information about the quality of habitat. While ocean acidification is known to affect a wide range of marine organisms and processes, its effect on marine soundscapes and its reception by navigating oceanic larvae remains unknown. Here, we show that ocean acidification causes a switch in role of present-day soundscapes from attractor to repellent in the auditory preferences in a temperate larval fish. Using natural CO2 vents as analogues of future ocean conditions, we further reveal that ocean acidification can impact marine soundscapes by profoundly diminishing their biological sound production. An altered soundscape poorer in biological cues indirectly penalizes oceanic larvae at settlement stage because both control and CO2-treated fish larvae showed lack of any response to such future soundscapes. These indirect and direct effects of ocean acidification put at risk the complex processes of larval dispersal and settlement. PMID:26763221

  17. Not All Larvae Stay Close to Home: Insights into Marine Population Connectivity with a Focus on the Brown Surgeonfish (Acanthurus nigrofuscus)

    PubMed Central

    Eble, Jeff A.; Rocha, Luiz A.; Craig, Matthew T.; Bowen, Brian W.

    2014-01-01

    Recent reports of localized larval recruitment in predominately small-range fishes are countered by studies that show high genetic connectivity across large oceanic distances. This discrepancy may result from the different timescales over which genetic and demographic processes operate or rather may indicate regular long-distance dispersal in some species. Here, we contribute an analysis of mtDNA cytochrome b diversity in the widely distributed Brown Surgeonfish (Acanthurus nigrofuscus; N = 560), which revealed significant genetic structure only at the extremes of the range (ΦCT = 0.452; P < .001). Collections from Hawaii to the Eastern Indian Ocean comprise one large, undifferentiated population. This pattern of limited genetic subdivision across reefs of the central Indo-Pacific has been observed in a number of large-range reef fishes. Conversely, small-range fishes are often deeply structured over the same area. These findings demonstrate population connectivity differences among species at biogeographic and evolutionary timescales, which likely translates into differences in dispersal ability at ecological and demographic timescales. While interspecific differences in population connectivity complicate the design of management strategies, the integration of multiscale connectivity patterns into marine resource planning will help ensure long-term ecosystem stability by preserving functionally diverse communities. PMID:25505914

  18. From egg production to recruits: Connectivity and inter-annual variability in the recruitment patterns of European anchovy in the northwestern Mediterranean

    NASA Astrophysics Data System (ADS)

    Ospina-Alvarez, Andres; Catalán, Ignacio A.; Bernal, Miguel; Roos, David; Palomera, Isabel

    2015-11-01

    We show the application of a Spatially-Explicit Individual-Based Model (SEIBM) to understand the recruitment process of European anchovy. The SEIBM is applied to simulate the effects of inter-annual variability in parental population spawning behavior and intensity, and ocean dynamics, on the dispersal of eggs and larvae from the spawning area in the Gulf of Lions (GoL) towards the coastal nursery areas in the GoL and Catalan Sea (northwestern Mediterranean Sea). For each of seven years (2003-2009), we initialize the SEIBM with the real positions of anchovy eggs during the spawning peak, from an acoustics-derived eggs production model. We analyze the effect of spawners' distribution, timing of spawning, and oceanographic conditions on the connectivity patterns, growth, dispersal distance and late-larval recruitment (14 mm larva recruits, R14) patterns. The area of influence of the Rhône river plume was identified as having a high probability of larval recruitment success (64%), but up to 36% of R14 larvae end up in the Catalan Coast. We demonstrate that the spatial paths of larvae differ dramatically from year to year, and suggest potential offshore nursery grounds. We showed that our simulations are coherent with existing recruitment proxies and therefore open new possibilities for fisheries management.

  19. Larval development of Evermannia zosterura (Perciformes: Gobiidae).

    PubMed

    González-Navarro, Enrique; Saldierna-Martínez, Ricardo Javier; Aceves-Medina, Gerardo

    2014-06-01

    Gobiidae is the most specious fish family in the world with almost 2 000 species, however only 11% of them have been described for their larval stages. The entire life cycle information is essential to understand the biology and ecology of this important fish group. Previous studies on zooplankton samples from Ensenada de La Paz, México, have shown the presence of several Gobiidae larvae and juveniles which were identified as Evermania zosterura. The main objective of this work was to describe the larval stages of this species, widely distributed in the Eastern tropical Pacific. The development of E. zosterura larvae was described based on 66 specimens. A total of 53 specimens were used to describe morphometrics and pigmentation patterns, while 13 specimens were cleared and stained, to obtain meristic characteristics. Cleared specimens had 30 to 31 total vertebrae; dorsal-fin elements: IV; 1, 13-14, anal-fin elements: 1, 13-14, and most had pterygiophore formula 4-111100. The combination of these characteristics confirmed these specimens as E. zosterura. The pigment pattern is similar throughout ontogeny. Larvae are characterized by having three to five dendritic melanophores along the post-anal ventral margin, four to nine smaller melanophores along the ventral margin between the isthmus and anus, and one on the midpoint of the dorsal margin of the tail. There is one small pigment spot on the angle of the jaw, and other on the tip of lower lip. There is an elongated internal pigment under the notochord, between the head and gas bladder. Notochord flexion starts near 3.5mm BL and ends at 4.6mm BL; transformalion to the juvenile stage is at about 13.6mm BL. Our conclusion is that the most useful characters to distinguish this species early-larval stages from those of similar species in the area, are the number of myomeres, the large melanophores (approximately uniformly in size) on the post anal ventral margin, and the elongate internal pigment under the notochord

  20. Modelling larval movement data from individual bioassays.

    PubMed

    McLellan, Chris R; Worton, Bruce J; Deasy, William; Birch, A Nicholas E

    2015-05-01

    We consider modelling the movements of larvae using individual bioassays in which data are collected at a high-frequency rate of five observations per second. The aim is to characterize the behaviour of the larvae when exposed to attractant and repellent compounds. Mixtures of diffusion processes, as well as Hidden Markov models, are proposed as models of larval movement. These models account for directed and localized movements, and successfully distinguish between the behaviour of larvae exposed to attractant and repellent compounds. A simulation study illustrates the advantage of using a Hidden Markov model rather than a simpler mixture model. Practical aspects of model estimation and inference are considered on extensive data collected in a study of novel approaches for the management of cabbage root fly. PMID:25764283

  1. Lagrangian simulations and interannual variability of anchovy egg and larva dispersal in the Sicily Channel

    NASA Astrophysics Data System (ADS)

    Palatella, Luigi; Bignami, Francesco; Falcini, Federico; Lacorata, Guglielmo; Lanotte, Alessandra S.; Santoleri, Rosalia

    2014-02-01

    The interannual variability in the transport of anchovy eggs and larvae in the Sicily Channel, relatively to the period 1999-2012, is studied by means of numerical simulations of the Mediterranean Forecasting System (MFS) circulation model provided by INGV. Subgrid-scale dynamics not resolved by the MFS model is parameterized in terms of kinematic fields. The latter affect small-scale tracer relative dispersion, while leaving the mean large-scale advection substantially unchanged. A Lagrangian Transport Index (LTI) can be defined to characterize the efficiency of the main currents, e.g., the Atlantic Ionian Stream, in connecting spawning and nursery areas to each other. In our case, this indicator comes from the first arrival time statistics of tracers traveling from a spawning area near Sciacca to a nursery area in proximity of Cape Passero. We observe, on the basis of LTI values, that there are years when the Lagrangian connectivity is very efficient (2004, 2008, 2012) and years when it is weak (2000, 2001, 2003, 2010). Lagrangian indicators like the LTI concur to explain observed fluctuations of larval density and, also, can be employed, more in general, in multivariate models of population dynamics.

  2. Bean Type Modifies Larval Competition in Zabrotes subfasciatus (Chrysomelidae: Bruchinae).

    PubMed

    Oliveira, S O D; Rodrigues, A S; Vieira, J L; Rosi-Denadai, C A; Guedes, N M P; Guedes, R N C

    2015-08-01

    Larval competition is particularly prevalent among grain beetles that remain within their mother-selected grain throughout development, and the behavioral process of competition is usually inferred by the competition outcome. The Mexican bean weevil Zabrotes subfasciatus (Boheman) is subjected to resource availability variation because of the diversity of common bean types and sizes, from small (e.g., kidney beans) to large (e.g., cranberry beans). The competition process was identified in the Mexican bean weevil reared on kidney and cranberry beans by inference from the competition outcome and by direct observation through digital X-ray imaging. Increased larval density negatively affected adult emergence in kidney beans and reduced adult body mass in both kidney and cranberry beans. Developmental time was faster in cranberry beans. The results allowed for increased larval fitness (i.e., higher larval biomass produced per grain), with larval density reaching a maximum plateau >5 hatched larvae per kidney bean, whereas in cranberry beans, larval fitness linearly increased with density to 13 hatched larvae per bean. These results, together with X-ray imaging without evidence of direct aggressive interaction among larvae, indicate scramble competition, with multiple larvae emerging per grain. However, higher reproductive output was detected for adults from lower density competition with better performance on cranberry beans. Larger populations and fitter adults are expected in intermediate larval densities primarily in cranberry beans where grain losses should be greater. PMID:26470357

  3. Nectar sugar limits larval growth of solitary bees (Hymenoptera: Megachilidae).

    PubMed

    Burkle, Laura; Irwin, Rebecca

    2009-08-01

    The bottom-up effects of plant food quality and quantity can affect the growth, survival, and reproduction of herbivores. The larvae of solitary bee pollinators, consumers of nectar and pollen, are also herbivores. Although pollen quantity and quality are known to be important for larval growth, little is known about how nectar quality limits solitary bee performance. By adding different levels of nectar sugar directly to solitary bee provisions in the subalpine of Colorado, we tested the degree to which larval performance (development time, mass, and survival) was limited by nectar sugar. We found that larval growth increased with nectar sugar addition, with the highest larval mass in the high nectar-sugar addition treatment (50% honey solution). The shortest larval development time was observed in the low nectar-sugar addition treatment (25% honey solution). Neither low nor high nectar-sugar addition affected larval survival. This study suggests that, in addition to pollen, nectar-sugar concentration can limit solitary bee larval growth and development, and nectar should be considered more explicitly as a currency governing foraging decisions related to producing optimally sized offspring. The availability and sugar content of nectar may scale up to affect bee fitness, population dynamics, and plant-pollinator mutualisms. PMID:19689912

  4. Dimethylsulfoniopropionate (DMSP) Increases Survival of Larval Sablefish, Anoplopoma fimbria.

    PubMed

    Lee, Jonathan S F; Poretsky, Rachel S; Cook, Matthew A; Reyes-Tomassini, Jose J; Berejikian, Barry A; Goetz, Frederick W

    2016-06-01

    High concentrations of dimethylsulfoniopropionate (DMSP), a chemical compound released by lysed phytoplankton, may indicate high rates of grazing by zooplankton and may thus be a foraging cue for planktivorous fishes. Previous studies have shown that some planktivorous fishes and birds aggregate or alter locomotory behavior in response to this chemical cue, which is likely adaptive because it helps them locate prey. These behavioral responses have been demonstrated in juveniles and adults, but no studies have tested for effects on larval fish. Larvae suffer from high mortality rates and are vulnerable to starvation. While larvae are generally thought to be visual predators, they actually have poor vision and cryptic prey. Thus, larval fish should benefit from a chemical cue that provides information on prey abundance. We reared larval sablefish, Anoplopoma fimbria, for one week and supplemented feedings with varying concentrations of DMSP to test the hypothesis that DMSP affects larval survival. Ecologically relevant DMSP concentrations increased larval survival by up to 70 %, which has implications for production in aquaculture and recruitment in nature. These results provide a new tool for increasing larval production in aquaculture and also suggest that larvae may use DMSP as an olfactory cue. The release of DMSP may be a previously unappreciated mechanism through which phytoplankton affect larval survival and recruitment. PMID:27306913

  5. Turbulent shear spurs settlement in larval sea urchins

    PubMed Central

    Gaylord, Brian; Hodin, Jason; Ferner, Matthew C.

    2013-01-01

    Marine invertebrates commonly produce larvae that disperse in ocean waters before settling into adult shoreline habitat. Chemical and other seafloor-associated cues often facilitate this latter transition. However, the range of effectiveness of such cues is limited to small spatial scales, creating challenges for larvae in finding suitable sites at which to settle, especially given that they may be carried many kilometers by currents during their planktonic phase. One possible solution is for larvae to use additional, broader-scale environmental signposts to first narrow their search to the general vicinity of a candidate settlement location. Here we demonstrate strong effects of just such a habitat-scale cue, one with the potential to signal larvae that they have arrived in appropriate coastal areas. Larvae of the purple sea urchin (Strongylocentrotus purpuratus) exhibit dramatic enhancement in settlement following stimulation by turbulent shear typical of wave-swept shores where adults of this species live. This response manifests in an unprecedented fashion relative to previously identified cues. Turbulent shear does not boost settlement by itself. Instead, it drives a marked developmental acceleration that causes “precompetent” larvae refractory to chemical settlement inducers to immediately become “competent” and thereby reactive to such inducers. These findings reveal an unrecognized ability of larval invertebrates to shift the trajectory of a major life history event in response to fluid-dynamic attributes of a target environment. Such an ability may improve performance and survival in marine organisms by encouraging completion of their life cycle in advantageous locations. PMID:23572585

  6. Ecology of larval trematodes in three marine gastropods.

    PubMed

    Curtis, Lawrence A

    2002-01-01

    To comprehend natural host-parasite systems, ecological knowledge of both hosts and parasites is critical. Here I present a view of marine systems based on the snail Ilyanassa obsoleta and its trematodes. This system is reviewed and two others, those of the snails Cerithidea californica and Littorina littorea, are then summarized and compared. Trematodes can profoundly affect the physiology, behaviour and spatial distribution of hosts. Studying these systems is challenging because trematodes are often embedded in host populations in unappreciated ways. Trematode prevalence is variable, but can be high in populations of all three hosts. Conditions under which single- and multiple-species infections can accumulate are considered. Adaptive relations between species are likely the most important and potentials for adaptation of parasites to hosts, hosts to parasites, and parasites to other parasites are also considered. Even if colonization rate is low, a snail population can develop high trematode prevalence, if infections persist long and the host is long-lived and abundant. Trematodes must be adapted to use their snail hosts. However, both I. obsoleta and L. littorea possess highly dispersed planktonic larvae and trematode prevalence is variable among snail populations. Host adaptation to specific infections, or even to trematodes in general, is unlikely because routine exposure to trematodes is improbable. Crawl-away juveniles of C. californica make adaptation to trematodes in that system a possibility. Trematode species in all three systems are not likely adapted to each other. Multiple-species infections are rare and definitive hosts scatter parasite eggs among snail populations with variable prevalences. Routine co-occurrence of trematodes in snails is thus unlikely. Adaptations of these larval trematodes to inhabit the snail host must, then, be the basis for what happens when they do co-occur. PMID:12396215

  7. High Connectivity of Animal Populations in Deep-Sea Hydrothermal Vent Fields in the Central Indian Ridge Relevant to Its Geological Setting

    PubMed Central

    Beedessee, Girish; Watanabe, Hiromi; Ogura, Tomomi; Nemoto, Suguru; Yahagi, Takuya; Nakagawa, Satoshi; Nakamura, Kentaro; Takai, Ken; Koonjul, Meera; Marie, Daniel E. P.

    2013-01-01

    Dispersal ability plays a key role in the maintenance of species in spatially and temporally discrete niches of deep-sea hydrothermal vent environments. On the basis of population genetic analyses in the eastern Pacific vent fields, dispersal of animals in the mid-oceanic ridge systems generally appears to be constrained by geographical barriers such as trenches, transform faults, and microplates. Four hydrothermal vent fields (the Kairei and Edmond fields near the Rodriguez Triple Junction, and the Dodo and Solitaire fields in the Central Indian Ridge) have been discovered in the mid-oceanic ridge system of the Indian Ocean. In the present study, we monitored the dispersal of four representative animals, Austinograea rodriguezensis, Rimicaris kairei, Alviniconcha and the scaly-foot gastropods, among these vent fields by using indirect methods, i.e., phylogenetic and population genetic analyses. For all four investigated species, we estimated potentially high connectivity, i.e., no genetic difference among the populations present in vent fields located several thousands of kilometers apart; however, the direction of migration appeared to differ among the species, probably because of different dispersal strategies. Comparison of the intermediate-spreading Central Indian Ridge with the fast-spreading East Pacific Rise and slow-spreading Mid-Atlantic Ridge revealed the presence of relatively high connectivity in the intermediate- and slow-spreading ridge systems. We propose that geological background, such as spreading rate which determines distance among vent fields, is related to the larval dispersal and population establishment of vent-endemic animal species, and may play an important role in controlling connectivity among populations within a biogeographical province. PMID:24358117

  8. High connectivity of animal populations in deep-sea hydrothermal vent fields in the Central Indian Ridge relevant to its geological setting.

    PubMed

    Beedessee, Girish; Watanabe, Hiromi; Ogura, Tomomi; Nemoto, Suguru; Yahagi, Takuya; Nakagawa, Satoshi; Nakamura, Kentaro; Takai, Ken; Koonjul, Meera; Marie, Daniel E P

    2013-01-01

    Dispersal ability plays a key role in the maintenance of species in spatially and temporally discrete niches of deep-sea hydrothermal vent environments. On the basis of population genetic analyses in the eastern Pacific vent fields, dispersal of animals in the mid-oceanic ridge systems generally appears to be constrained by geographical barriers such as trenches, transform faults, and microplates. Four hydrothermal vent fields (the Kairei and Edmond fields near the Rodriguez Triple Junction, and the Dodo and Solitaire fields in the Central Indian Ridge) have been discovered in the mid-oceanic ridge system of the Indian Ocean. In the present study, we monitored the dispersal of four representative animals, Austinograea rodriguezensis, Rimicaris kairei, Alviniconcha and the scaly-foot gastropods, among these vent fields by using indirect methods, i.e., phylogenetic and population genetic analyses. For all four investigated species, we estimated potentially high connectivity, i.e., no genetic difference among the populations present in vent fields located several thousands of kilometers apart; however, the direction of migration appeared to differ among the species, probably because of different dispersal strategies. Comparison of the intermediate-spreading Central Indian Ridge with the fast-spreading East Pacific Rise and slow-spreading Mid-Atlantic Ridge revealed the presence of relatively high connectivity in the intermediate- and slow-spreading ridge systems. We propose that geological background, such as spreading rate which determines distance among vent fields, is related to the larval dispersal and population establishment of vent-endemic animal species, and may play an important role in controlling connectivity among populations within a biogeographical province. PMID:24358117

  9. 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

  10. Increased Long-Flight Activity Triggered in Beet Armyworm by Larval Feeding on Diet Containing Cry1Ac Protoxin

    PubMed Central

    Jiang, Xing Fu; Chen, Jian; Zhang, Lei; Sappington, Thomas W.; Luo, Li Zhi

    2013-01-01

    Evaluating ecological safety and conducting pest risk analysis for transgenic crops are vitally important before their commercial planting. The beet armyworm, Spodoptera exigua, a long-distance migratory insect pest, is not a direct target of transgenic Cry1Ac-expressing cotton in China, but nevertheless it has recently become an important pest. Migrants leaving their natal field arrive in other appropriate habitat far away in a short time, often followed by larval outbreaks. S. exigua has low susceptibility to Cry1Ac. However, our results from laboratory experiments identified (i) sublethal effects of Cry1Ac protoxin on larval development rate, larval and pupal weight, and adult lifetime fecundity, and (ii) increased long-flight behavior triggered by Cry1Ac which may contribute to larval outbreaks elsewhere. No significant differences in larval mortality, pupation rate, adult emergence rate, longevity, pre-oviposition period, or oviposition period were observed between controls and larvae fed on artificial diet incorporating a low concentration of Cry1Ac protoxin. The negative sublethal effects on some developmental and reproductive traits and lack of effect on others suggest they do not contribute to the observed severity of S. exigua outbreaks after feeding on Cry1Ac cotton. Interestingly, the percentage of long fliers increased significantly when larvae were reared on diet containing either of two low-dose treatments of Cry1Ac, suggesting a possible increased propensity to disperse long distances triggered by Cry1Ac. We hypothesize that negative effects on development and reproduction caused by Cry1Ac in the diet are offset by increased flight propensity triggered by the poor food conditions, thereby improving the chances of escaping adverse local conditions before oviposition. Increased long-flight propensity in turn may amplify the area damaged by outbreak populations. This phenomenon might be common in other migratory insect pests receiving sublethal doses

  11. Mosquito larval source management for controlling malaria

    PubMed Central

    Tusting, Lucy S; Thwing, Julie; Sinclair, David; Fillinger, Ulrike; Gimnig, John; Bonner, Kimberly E; Bottomley, Christian; Lindsay, Steven W

    2015-01-01

    Background Malaria is an important cause of illness and death in people living in many parts of the world, especially sub-Saharan Africa. Long-lasting insecticide treated bed nets (LLINs) and indoor residual spraying (IRS) reduce malaria transmission by targeting the adult mosquito vector and are key components of malaria control programmes. However, mosquito numbers may also be reduced by larval source management (LSM), which targets mosquito larvae as they mature in aquatic habitats. This is conducted by permanently or temporarily reducing the availability of larval habitats (habitat modification and habitat manipulation), or by adding substances to standing water that either kill or inhibit the development of larvae (larviciding). Objectives To evaluate the effectiveness of mosquito LSM for preventing malaria. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; EMBASE; CABS Abstracts; and LILACS up to 24 October 2012. We handsearched the Tropical Diseases Bulletin from 1900 to 2010, the archives of the World Health Organization (up to 11 February 2011), and the literature database of the Armed Forces Pest Management Board (up to 2 March 2011). We also contacted colleagues in the field for relevant articles. Selection criteria We included cluster randomized controlled trials (cluster-RCTs), controlled before-and-after trials with at least one year of baseline data, and randomized cross-over trials that compared LSM with no LSM for malaria control. We excluded trials that evaluated biological control of anopheline mosquitoes with larvivorous fish. Data collection and analysis At least two authors assessed each trial for eligibility. We extracted data and at least two authors independently determined the risk of bias in the included studies. We resolved all disagreements through discussion with a third author. We analyzed the data using Review Manager 5 software

  12. Functional Regeneration Following Spinal Transection Demonstrated in the Isolated Spinal Cord of the Larval Sea Lamprey

    NASA Astrophysics Data System (ADS)

    Cohen, A. H.; Mackler, S. A.; Selzer, M. E.

    1986-04-01

    Axons in the larval sea lamprey can regenerate across the site of a spinal cord transection and form functioning synapses with some of their normal target neurons. The animals recover normal-appearing locomotion, but whether the regenerating axons and their synaptic connections are capable of playing a functional role during this behavior is unknown. To test this, ``fictive'' swimming was induced in the isolated spinal cord by the addition of D-glutamate to the bathing solution. Ventral root discharges of segments above and below a healed transection showed a high degree of phase-locking. This strongly suggests that the behavioral recovery is mediated by regenerated functional synaptic connections subserving intersegmental coordination of the central pattern generator for locomotion.

  13. Connected Traveler

    SciTech Connect

    Schroeder, Alex

    2015-11-01

    The Connected Traveler project is a multi-disciplinary undertaking that seeks to validate potential for transformative transportation system energy savings by incentivizing efficient traveler behavior. This poster outlines various aspects of the Connected Traveler project, including market opportunity, understanding traveler behavior and decision-making, automation and connectivity, and a projected timeline for Connected Traveler's key milestones.

  14. Behavioral analysis of the escape response in larval zebrafish

    NASA Astrophysics Data System (ADS)

    Feng, Ruopei; Girdhar, Kiran; Chemla, Yann; Gruebele, Martin

    The behavior of larval zebrafish is of great interest because the limited number of locomotor neurons in larval zebrafish couples with its rich repertoire of movements as a vertebrate animal. Current research uses a priori-selected parameters to describe their swimming behavior while our lab has built a parameter-free model based on singular value decomposition analysis to characterize it. Our previous work has analyzed the free swimming of larval zebrafish and presented a different picture from the current classification of larval zebrafish locomotion. Now we are extending this work to the studies of their escape response to acoustic stimulus. Analysis has shown intrinsic difference in the locomotion between escape response and free swimming.

  15. Genetic differentiation and connectivity of morphological types of the broadcast-spawning coral Galaxea fascicularis in the Nansei Islands, Japan.

    PubMed

    Nakajima, Yuichi; Zayasu, Yuna; Shinzato, Chuya; Satoh, Noriyuki; Mitarai, Satoshi

    2016-03-01

    Population connectivity resulting from larval dispersal is essential for the maintenance or recovery of populations in marine ecosystems, including coral reefs. Studies of species diversity and genetic connectivity within species are essential for the conservation of corals and coral reef ecosystems. We analyzed mitochondrial DNA sequence types and microsatellite genotypes of the broadcast-spawning coral, Galaxea fascicularis, from four regions in the subtropical Nansei Islands in the northwestern Pacific Ocean. Two types (soft and hard types) of nematocyst morphology are known in G. fascicularis and are significantly correlated with the length of a mitochondrial DNA noncoding sequence (soft type: mt-L; hard type: mt-S type). Using microsatellites, significant genetic differentiation was detected between the mitochondrial DNA sequence types in all regions. We also found a third genetic cluster (mt-L+), and this unexpected type may be a cryptic species of Galaxea. High clonal diversity was detected in both mt-L and mt-S types. Significant genetic differentiation, which was found among regions within a given type (F ST = 0.009-0.024, all Ps ≤ 0.005 in mt-L; 0.009-0.032, all Ps ≤ 0.01 in mt-S), may result from the shorter larval development than in other broadcast-spawning corals, such as the genus Acropora. Nevertheless, intraspecific genetic diversity and connectivity have been maintained, and with both sexual and asexual reproduction, this species appears to have a potential for the recovery of populations after disturbance. PMID:27087925

  16. Reduction of a larval herring population by jellyfish predator.

    PubMed

    Möller, H

    1984-05-11

    The scyphomedusa Aurelia aurita consumes large amounts of yolk-sac herring larvae in Kiel Fjord. The decline of the larval herring population in late spring coincides with a major population growth of the jellyfish. The size of the larval herring population seems to be more significantly affected by the size of the predator stock than by the size of the parental herring stock. PMID:17838355

  17. Contribution of larval nutrition to adult reproduction in Drosophila melanogaster.

    PubMed

    Aguila, Jerell R; Hoshizaki, Deborah K; Gibbs, Allen G

    2013-02-01

    Within the complex life cycle of holometabolous insects, nutritional resources acquired during larval feeding are utilized by the pupa and the adult. The broad features of the transfer of larval resources to the pupae and the allocation of larval resources in the adult have been described by studies measuring and tracking macronutrients at different developmental stages. However, the mechanisms of resource transfer from the larva and the factors regulating the allocation of these resources in the adult between growth, reproduction and somatic maintenance are unknown. Drosophila melanogaster presents a tractable system in which to test cellular and tissue mechanisms of resource acquisition and allocation because of the detailed understanding of D. melanogaster development and the experimental tools to manipulate its tissues across developmental stages. In previous work, we demonstrated that the fat body of D. melanogaster larvae is important for survival of starvation stress in the young adult, and suggested that programmed cell death of the larval fat cells in the adult is important for allocation of resources for female reproduction. Here, we describe the temporal uptake of larval-derived carbon by the ovaries, and demonstrate the importance of larval fat-cell death in the maturation of the ovary and in fecundity. Larvae and adults were fed stable carbon isotopes to follow the acquisition of larval-derived carbon by the adult ovaries. We determined that over half of the nutrients acquired by the ovaries in 2-day-old adult females are dependent upon the death of the fat cells. Furthermore, when programmed cell death is inhibited in the larval fat cells, ovarian development was depressed and fecundity was reduced. PMID:23038728

  18. Colloidal Dispersions

    NASA Astrophysics Data System (ADS)

    Russel, W. B.; Saville, D. A.; Schowalter, W. R.

    1992-03-01

    The book covers the physical side of colloid science from the individual forces acting between submicron particles suspended in a liquid through the resulting equilibrium and dynamic properties. The relevant forces include Brownian motion, electrostatic repulsion, dispersion attraction, both attraction and repulsion due to soluble polymer, and viscous forces due to relative motion between the particles and the liquid. The balance among Brownian motion and the interparticle forces decides the questions of stability and phase behavior. Imposition of external fields produces complex effects, i.e. electrokinetic phenomena (electric field), sedimentation (gravitational field), diffusion (concentration/chemical potential gradient), and non-Newtonian rheology (shear field). The treatment aims to impart a sound, quantitative understanding based on fundamental theory and experiments with well-characterized model systems. This broad grasp of the fundamentals lends insight and helps to develop the intuitive sense needed to isolate essential features of technological problems and design critical experiments. Some exposure to fluid mechanics, statistical mechanics, and electricity and magnetism is assumed, but each subject is reintroduced in a self-contained manner.

  19. Dispersion in alluvial convergent estuaries

    NASA Astrophysics Data System (ADS)

    Zhang, Zhilin; Savenije, Hubert H. G.

    2016-04-01

    The Van der Burgh's equation for longitudinal effective dispersion is a purely empirical method with practical implications. Its application to the effective tidal average dispersion under equilibrium conditions appears to have excellent performance in a wide range of alluvial estuaries. In this research, we try to find out the physical meaning of Van der Burgh's coefficient. Researchers like MacCready, Fischer, Kuijper, Hansen and Rattray have tried to split up dispersion into its constituents which did not do much to explain overall behaviour. In addition, traditional literature on dispersion is mostly related to flumes with constant cross-section. This research is about understanding the Van der Burgh's coefficient facing the fact that natural estuaries have exponentially varying cross-section. The objective is to derive a simple 1-D model considering both longitudinal and lateral mixing processes based on field observations (theoretical derivation). To that effect, we connect dispersion with salinity using the salt balance equation. Then we calculate the salinity along the longitudinal direction and compare it to the observed salinity. Calibrated dispersion coefficients in a range of estuaries are then compared with new expressions for the Van der Burgh's coefficient K and it is analysed if K varies from estuary to estuary. The set of reliable data used will be from estuaries: Kurau, Perak, Bernam, Selangor, Muar, Endau, Maputo, Thames, Corantijn, Sinnamary, Mae Klong, Lalang, Limpopo, Tha Chin, Chao Phraya, Edisto and Elbe.

  20. From Shelf to Shelf: Assessing Historical and Contemporary Genetic Differentiation and Connectivity across the Gulf of Mexico in Gag, Mycteroperca microlepis

    PubMed Central

    Jue, Nathaniel K.; Brulé, Thierry; Coleman, Felicia C.; Koenig, Christopher C.

    2015-01-01

    Describing patterns of connectivity among populations of species with widespread distributions is particularly important in understanding the ecology and evolution of marine species. In this study, we examined patterns of population differentiation, migration, and historical population dynamics using microsatellite and mitochondrial loci to test whether populations of the epinephelid fish, Gag, Mycteroperca microlepis, an important fishery species, are genetically connected across the Gulf of Mexico and if so, whether that connectivity is attributable to either contemporary or historical processes. Populations of Gag on the Campeche Bank and the West Florida Shelf show significant, but low magnitude, differentiation. Time since divergence/expansion estimates associated with historical population dynamics indicate that any population or spatial expansions indicated by population genetics would have likely occurred in the late Pleistocene. Using coalescent-based approaches, we find that the best model for explaining observed spatial patterns of contemporary genetic variation is one of asymmetric gene flow, with movement from Campeche Bank to the West Florida Shelf. Both estimated migration rates and ecological data support the hypothesis that Gag populations throughout the Gulf of Mexico are connected via present day larval dispersal. Demonstrating this greatly expanded scale of connectivity for Gag highlights the influence of “ghost” populations (sensu Beerli) on genetic patterns and presents a critical consideration for both fisheries management and conservation of this and other species with similar genetic patterns. PMID:25856095

  1. Imaging fictive locomotor patterns in larval Drosophila

    PubMed Central

    Bayley, Timothy G.; Taylor, Adam L.; Berni, Jimena; Bate, Michael; Hedwig, Berthold

    2015-01-01

    We have established a preparation in larval Drosophila to monitor fictive locomotion simultaneously across abdominal and thoracic segments of the isolated CNS with genetically encoded Ca2+ indicators. The Ca2+ signals closely followed spiking activity measured electrophysiologically in nerve roots. Three motor patterns are analyzed. Two comprise waves of Ca2+ signals that progress along the longitudinal body axis in a posterior-to-anterior or anterior-to-posterior direction. These waves had statistically indistinguishable intersegmental phase delays compared with segmental contractions during forward and backward crawling behavior, despite being ∼10 times slower. During these waves, motor neurons of the dorsal longitudinal and transverse muscles were active in the same order as the muscle groups are recruited during crawling behavior. A third fictive motor pattern exhibits a left-right asymmetry across segments and bears similarities with turning behavior in intact larvae, occurring equally frequently and involving asymmetry in the same segments. Ablation of the segments in which forward and backward waves of Ca2+ signals were normally initiated did not eliminate production of Ca2+ waves. When the brain and subesophageal ganglion (SOG) were removed, the remaining ganglia retained the ability to produce both forward and backward waves of motor activity, although the speed and frequency of waves changed. Bilateral asymmetry of activity was reduced when the brain was removed and abolished when the SOG was removed. This work paves the way to studying the neural and genetic underpinnings of segmentally coordinated motor pattern generation in Drosophila with imaging techniques. PMID:26311188

  2. Basic Gravitational Reflexes in the Larval Frog

    NASA Technical Reports Server (NTRS)

    Cochran, Stephen L.

    1996-01-01

    This investigation was designed to determine how a primitive vertebrate, the bullfrog tadpole, is able to sense and process gravitational stimuli. Because of the phylogenetic similarities of the vestibular systems in all vertebrates, the understanding of the gravitational reflexes in this relatively simple vertebrate should elucidate a skeletal framework on a elementary level, upon which the more elaborate reflexes of higher vertebrates may be constructed. The purpose of this study was to understand how the nervous system of the larval amphibian processes gravitational information. This study involved predominantly electrophysiological investigations of the isolated, alert (forebrain removed) bullfrog tadpole head. The focus of these experiments is threefold: (1) to understand from whole extraocular nerve recordings the signals sent to the eye following static gravitational tilt of the head; (2) to localize neuronal centers responsible for generating these signals through reversible pharmacological ablation of these centers; and (3) to record intracellularly from neurons within these centers in order to determine the single neuron's role in the overall processing of the center. This study has provided information on the mechanisms by which a primitive vertebrate processes gravitational reflexes.

  3. Imaging fictive locomotor patterns in larval Drosophila.

    PubMed

    Pulver, Stefan R; Bayley, Timothy G; Taylor, Adam L; Berni, Jimena; Bate, Michael; Hedwig, Berthold

    2015-11-01

    We have established a preparation in larval Drosophila to monitor fictive locomotion simultaneously across abdominal and thoracic segments of the isolated CNS with genetically encoded Ca(2+) indicators. The Ca(2+) signals closely followed spiking activity measured electrophysiologically in nerve roots. Three motor patterns are analyzed. Two comprise waves of Ca(2+) signals that progress along the longitudinal body axis in a posterior-to-anterior or anterior-to-posterior direction. These waves had statistically indistinguishable intersegmental phase delays compared with segmental contractions during forward and backward crawling behavior, despite being ∼10 times slower. During these waves, motor neurons of the dorsal longitudinal and transverse muscles were active in the same order as the muscle groups are recruited during crawling behavior. A third fictive motor pattern exhibits a left-right asymmetry across segments and bears similarities with turning behavior in intact larvae, occurring equally frequently and involving asymmetry in the same segments. Ablation of the segments in which forward and backward waves of Ca(2+) signals were normally initiated did not eliminate production of Ca(2+) waves. When the brain and subesophageal ganglion (SOG) were removed, the remaining ganglia retained the ability to produce both forward and backward waves of motor activity, although the speed and frequency of waves changed. Bilateral asymmetry of activity was reduced when the brain was removed and abolished when the SOG was removed. This work paves the way to studying the neural and genetic underpinnings of segmentally coordinated motor pattern generation in Drosophila with imaging techniques. PMID:26311188

  4. Dissection of larval CNS in Drosophila melanogaster.

    PubMed

    Hafer, Nathaniel; Schedl, Paul

    2006-12-01

    The central nervous system (CNS) of Drosophila larvae is complex and poorly understood. One way to investigate the CNS is to use immunohistochemistry to examine the expression of various novel and marker proteins. Staining of whole larvae is impractical because the tough cuticle prevents antibodies from penetrating inside the body cavity. In order to stain these tissues it is necessary to dissect the animal prior to fixing and staining. In this article we demonstrate how to dissect Drosophila larvae without damaging the CNS. Begin by tearing the larva in half with a pair of fine forceps, and then turn the cuticle "inside-out" to expose the CNS. If the dissection is performed carefully the CNS will remain attached to the cuticle. We usually keep the CNS attached to the cuticle throughout the fixation and staining steps, and only completely remove the CNS from the cuticle just prior to mounting the samples on glass slides. We also show some representative images of a larval CNS stained with Eve, a transcription factor expressed in a subset of neurons in the CNS. The article concludes with a discussion of some of the practical uses of this technique and the potential difficulties that may arise. PMID:18704179

  5. Immunoregulation in larval Echinococcus multilocularis infection.

    PubMed

    Wang, J; Gottstein, B

    2016-03-01

    Alveolar echinococcosis (AE) is a clinically very severe zoonotic helminthic disease, characterized by a chronic progressive hepatic damage caused by the continuous proliferation of the larval stage (metacestode) of Echinococcus multilocularis. The proliferative potential of the parasite metacestode tissue is dependent on the nature/function of the periparasitic immune-mediated processes of the host. Immune tolerance and/or down-regulation of immunity are a marked characteristic increasingly observed when disease develops towards its chronic (late) stage of infection. In this context, explorative studies have clearly shown that T regulatory (Treg) cells play an important role in modulating and orchestrating inflammatory/immune reactions in AE, yielding a largely Th2-biased response, and finally allowing thus long-term parasite survival, proliferation and maturation. AE is fatal if not treated appropriately, but the current benzimidazole chemotherapy is far from optimal, and novel options for control are needed. Future research should focus on the elucidation of the crucial immunological events that lead to anergy in AE, and focus on providing a scientific basis for the development of novel and more effective immunotherapeutical options to support cure AE by abrogating anergy, anticipating also that a combination of immuno- and chemotherapy could provide a synergistic therapeutical effect. PMID:26536823

  6. Autophagy precedes apoptosis during the remodeling of silkworm larval midgut.

    PubMed

    Franzetti, Eleonora; Huang, Zhi-Jun; Shi, Yan-Xia; Xie, Kun; Deng, Xiao-Juan; Li, Jian-Ping; Li, Qing-Rong; Yang, Wan-Ying; Zeng, Wen-Nian; Casartelli, Morena; Deng, Hui-Min; Cappellozza, Silvia; Grimaldi, Annalisa; Xia, Qingyou; Feng, Qili; Cao, Yang; Tettamanti, Gianluca

    2012-03-01

    Although several features of apoptosis and autophagy have been reported in the larval organs of Lepidoptera during metamorphosis, solid experimental evidence for autophagy is still lacking. Moreover, the role of the two processes and the nature of their relationship are still cryptic. In this study, we perform a cellular, biochemical and molecular analysis of the degeneration process that occurs in the larval midgut of Bombyx mori during larval-adult transformation, with the aim to analyze autophagy and apoptosis in cells that die under physiological conditions. We demonstrate that larval midgut degradation is due to the concerted action of the two mechanisms, which occur at different times and have different functions. Autophagy is activated from the wandering stage and reaches a high level of activity during the spinning and prepupal stages, as demonstrated by specific autophagic markers. Our data show that the process of autophagy can recycle molecules from the degenerating cells and supply nutrients to the animal during the non-feeding period. Apoptosis intervenes later. In fact, although genes encoding caspases are transcribed at the end of the larval period, the activity of these proteases is not appreciable until the second day of spinning and apoptotic features are observable from prepupal phase. The abundance of apoptotic features during the pupal phase, when the majority of the cells die, indicates that apoptosis is actually responsible for cell death and for the disappearance of larval midgut cells. PMID:22127643

  7. Can Georges Bank larval cod survive on a calanoid diet?

    NASA Astrophysics Data System (ADS)

    Lynch, Daniel R.; Lewis, Craig V. W.; Werner, Francisco E.

    A simple conceptual model is developed for larval fish feeding on stage-structured prey populations, in an Eulerian framework. The model combines simplified contemporary models of larval fish trophodynamics, zooplankton population dynamics, and hydrodynamic turbulence. The Eulerian view allows instructive maps of larval feeding and growth rates for individual prey species, alone or in combination. Decadally averaged MARMAP surveys of Calanus finmarchicus and Pseudocalanus spp. are analyzed for the March-April period. Quasi-static population dynamics are used to infer the abundance of the smallest stages from adult female abundance. Computed growth rates show that Calanus alone is insufficient to support the smallest cod larvae (4 and 6 mm), but provides good growth (⩾10%/day) for large larvae (10, 12 mm). Pseudocalanus alone provides generally good growth for all larvae but is mismatched spatially with observed cod spawning and subsequent larval advection. Both species together provide good growth, matched spatially with larval cod, for 6 mm and larger larvae. A dietary supplement beyond these two species is needed for the smallest larvae. The procedure provides a general method for mapping observations of zooplankton abundance, distribution and reproductive status, and their relevance to larval fish survival, when the smallest stages are not observable.

  8. 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

  9. A role for blind DN2 clock neurons in temperature entrainment of the Drosophila larval brain.

    PubMed

    Picot, Marie; Klarsfeld, André; Chélot, Elisabeth; Malpel, Sébastien; Rouyer, François

    2009-07-01

    Circadian clocks synchronize to the solar day by sensing the diurnal changes in light and temperature. In adult Drosophila, the brain clock that controls rest-activity rhythms relies on neurons showing Period oscillations. Nine of these neurons are present in each larval brain hemisphere. They can receive light inputs through Cryptochrome (CRY) and the visual system, but temperature input pathways are unknown. Here, we investigate how the larval clock network responds to light and temperature. We focused on the CRY-negative dorsal neurons (DN2s), in which light-dark (LD) cycles set molecular oscillations almost in antiphase to all other clock neurons. We first showed that the phasing of the DN2s in LD depends on the pigment-dispersing factor (PDF) neuropeptide in four lateral neurons (LNs), and on the PDF receptor in the DN2s. In the absence of PDF signaling, these cells appear blind, but still synchronize to temperature cycles. Period oscillations in the DN2s were stronger in thermocycles than in LD, but with a very similar phase. Conversely, the oscillations of LNs were weaker in thermocycles than in LD, and were phase-shifted in synchrony with the DN2s, whereas the phase of the three other clock neurons was advanced by a few hours. In the absence of any other functional clock neurons, the PDF-positive LNs were entrained by LD cycles but not by temperature cycles. Our results show that the larval clock neurons respond very differently to light and temperature, and strongly suggest that the CRY-negative DN2s play a prominent role in the temperature entrainment of the network. PMID:19571122

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

    PubMed

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

    2016-06-21

    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

  11. Larval settlement and metamorphosis in a marine gastropod in response to multiple conspecific cues

    PubMed Central

    Koury, Spencer A.

    2016-01-01

    Larvae of the marine gastropod Crepidula fornicata must complete a transition from the plankton, where they are highly dispersed, to an aggregated group of benthic adults. Previous research has shown that selective settlement of larvae on conspecific adults is mediated by a water-borne chemical cue. However, variable experimental conditions have been used to study this cue, and standardization is needed in order to investigate factors that may have weak effects on settlement. In this study, we developed a time-course bioassay based on a full-factorial design with temporal blocking and statistical analysis of larval settlement rates in the lab. We tested this bioassay by examining settlement in the presence of an abiotic cue (KCl), and biotic cues (water conditioned with adult conspecifics and conspecific pedal mucus). Results confirmed settlement in the presence of both KCl and adult-conditioned water, and discovered the induction of settlement by pedal mucus. This optimized, standardized bioassay will be used in future experiments to characterize the complex process of larval settlement in C. fornicata, particularly to measure components of potentially small effect. PMID:27547586

  12. Larval settlement and metamorphosis in a marine gastropod in response to multiple conspecific cues.

    PubMed

    Cahill, Abigail E; Koury, Spencer A

    2016-01-01

    Larvae of the marine gastropod Crepidula fornicata must complete a transition from the plankton, where they are highly dispersed, to an aggregated group of benthic adults. Previous research has shown that selective settlement of larvae on conspecific adults is mediated by a water-borne chemical cue. However, variable experimental conditions have been used to study this cue, and standardization is needed in order to investigate factors that may have weak effects on settlement. In this study, we developed a time-course bioassay based on a full-factorial design with temporal blocking and statistical analysis of larval settlement rates in the lab. We tested this bioassay by examining settlement in the presence of an abiotic cue (KCl), and biotic cues (water conditioned with adult conspecifics and conspecific pedal mucus). Results confirmed settlement in the presence of both KCl and adult-conditioned water, and discovered the induction of settlement by pedal mucus. This optimized, standardized bioassay will be used in future experiments to characterize the complex process of larval settlement in C. fornicata, particularly to measure components of potentially small effect. PMID:27547586

  13. Distinct visual pathways mediate Drosophila larval light avoidance and circadian clock entrainment.

    PubMed

    Keene, Alex C; Mazzoni, Esteban O; Zhen, Jamie; Younger, Meg A; Yamaguchi, Satoko; Blau, Justin; Desplan, Claude; Sprecher, Simon G

    2011-04-27

    Visual organs perceive environmental stimuli required for rapid initiation of behaviors and can also entrain the circadian clock. The larval eye of Drosophila is capable of both functions. Each eye contains only 12 photoreceptors (PRs), which can be subdivided into two subtypes. Four PRs express blue-sensitive rhodopsin5 (rh5) and eight express green-sensitive rhodopsin6 (rh6). We found that either PR-subtype is sufficient to entrain the molecular clock by light, while only the Rh5-PR subtype is essential for light avoidance. Acetylcholine released from PRs confers both functions. Both subtypes of larval PRs innervate the main circadian pacemaker neurons of the larva, the neuropeptide PDF (pigment-dispersing factor)-expressing lateral neurons (LNs), providing sensory input to control circadian rhythms. However, we show that PDF-expressing LNs are dispensable for light avoidance, and a distinct set of three clock neurons is required. Thus we have identified distinct sensory and central circuitry regulating light avoidance behavior and clock entrainment. Our findings provide insights into the coding of sensory information for distinct behavioral functions and the underlying molecular and neuronal circuitry. PMID:21525293

  14. Congruent patterns of connectivity can inform management for broadcast spawning corals on the Great Barrier Reef.

    PubMed

    Lukoschek, Vimoksalehi; Riginos, Cynthia; van Oppen, Madeleine J H

    2016-07-01

    Connectivity underpins the persistence and recovery of marine ecosystems. The Great Barrier Reef (GBR) is the world's largest coral reef ecosystem and managed by an extensive network of no-take zones; however, information about connectivity was not available to optimize the network's configuration. We use multivariate analyses, Bayesian clustering algorithms and assignment tests of the largest population genetic data set for any organism on the GBR to date (Acropora tenuis, >2500 colonies; >50 reefs, genotyped for ten microsatellite loci) to demonstrate highly congruent patterns of connectivity between this common broadcast spawning reef-building coral and its congener Acropora millepora (~950 colonies; 20 reefs, genotyped for 12 microsatellite loci). For both species, there is a genetic divide at around 19°S latitude, most probably reflecting allopatric differentiation during the Pleistocene. GBR reefs north of 19°S are essentially panmictic whereas southern reefs are genetically distinct with higher levels of genetic diversity and population structure, most notably genetic subdivision between inshore and offshore reefs south of 19°S. These broadly congruent patterns of higher genetic diversities found on southern GBR reefs most likely represent the accumulation of alleles via the southward flowing East Australia Current. In addition, signatures of genetic admixture between the Coral Sea and outer-shelf reefs in the northern, central and southern GBR provide evidence of recent gene flow. Our connectivity results are consistent with predictions from recently published larval dispersal models for broadcast spawning corals on the GBR, thereby providing robust connectivity information about the dominant reef-building genus Acropora for coral reef managers. PMID:27085309

  15. Modeling habitat connectivity to inform reintroductions: a case study with the Chiricahua Leopard Frog

    USGS Publications Warehouse

    Jarchow, Christopher J; Hossack, Blake R.; Sigafus, Brent H.; Schwalbe, Cecil R.; Muths, Erin L.

    2016-01-01

    Managing species with intensive tools such as reintroduction may focus on single sites or entire landscapes. For vagile species, long-term persistence will require colonization and establishment in neighboring habitats. Therefore, both suitable colonization sites and suitable dispersal corridors between sites are required. Assessment of landscapes for both requirements can contribute to ranking and selection of reintroduction areas, thereby improving management success. Following eradication of invasive American Bullfrogs (Lithobates catesbeianus) from most of Buenos Aires National Wildlife Refuge (BANWR; Arizona, United States), larval Chiricahua Leopard Frogs (Lithobates chiricahuensis) from a private pond were reintroduced into three stock ponds. Populations became established at all three reintroduction sites followed by colonization of neighboring ponds in subsequent years. Our aim was to better understand colonization patterns by the federally threatened L. chiricahuensis which could help inform other reintroduction efforts. We assessed the influence of four landscape features on colonization. Using surveys from 2007 and information about the landscape, we developed a habitat connectivity model, based on electrical circuit theory, that identified potential dispersal corridors after explicitly accounting for imperfect detection of frogs. Landscape features provided little insight into why some sites were colonized and others were not, results that are likely because of the uniformity of the BANWR landscape. While corridor modeling may be effective in more-complex landscapes, our results suggest focusing on local habitat will be more useful at BANWR. We also illustrate that existing data, even when limited in spatial or temporal resolution, can provide information useful in formulating management actions.

  16. Does the zooplankton prey availability limit the larval habitats of pike in the Baltic Sea?

    NASA Astrophysics Data System (ADS)

    Kallasvuo, Meri; Salonen, Maiju; Lappalainen, Antti

    2010-01-01

    The objectives of this study were to (1) investigate whether the availability of suitable zooplankton prey limits the distribution of the coastal larval areas of pike ( Esox lucius) in two archipelago areas of the northern Baltic Sea and (2) compare the availability of zooplankton prey in spring between different types of coastal littoral habitat. According to the results, reed belt habitats formed by Phragmites australis constitute hot spots for zooplankton prey in the coastal ecosystem. During the spring, reed-covered shores of the inner archipelago maintained more than 10 times higher densities of copepods and cladocerans, the preferred prey for larval pike, compared to the other studied shores. Temperature conditions were also most favourable in the reed belt habitat. Thus, the reed belts of the inner and middle archipelago were shown to form the best habitat for larval pike in the coastal area of the northern Baltic Sea, and this was also the only habitat where pike larvae were found. Our results suggest that the poor survival and recruitment of pike in the outer archipelago, however, cannot exclusively be explained by sub-optimal feeding conditions of the larvae. There are also other important factors, presumably connected to the exposure to the open sea, that affect the distribution of the pike larvae. Our results, however, highlight the importance of sheltered coastal reed belt shores as reproduction habitat for spring-spawning fish in the northern Baltic Sea. Further, this study disproves the assumption that the seaweed bladder wrack ( Fucus vesiculosus) forms a reproduction habitat for pike in the coastal area.

  17. Do Larval Supply and Recruitment Vary among Chemosynthetic Environments of the Deep Sea?

    PubMed Central

    Metaxas, Anna; Kelly, Noreen E.

    2010-01-01

    Background The biological communities that inhabit chemosynthetic environments exist in an ephemeral and patchily distributed habitat with unique physicochemical properties that lead to high endemicity. Consequently, the maintenance and recovery from perturbation of the populations in these habitats is, arguably, mainly regulated by larval supply and recruitment. Methodology/Principal Findings We use data from the published scientific literature to: (1) compare the magnitudes of and variability in larval supply and settlement and recruitment at hydrothermal vents, seeps, and whale, wood and kelp falls; (2) explore factors that affect these life history processes, when information is available; and (3) explore taxonomic affinities in the recruit assemblages of the different chemosynthetic habitats, using multivariate statistical techniques. Larval supply at vents can vary across segments by several orders of magnitude for gastropods; for bivalves, supply is similar at vents on different segments, and at cold seeps. The limited information on larval development suggests that dispersal potential may be highest for molluscs from cold seeps, intermediate for siboglinids at vents and lowest for the whale-bone siboglinid Osedax. Settlement is poorly studied and only at vents and seeps, but tends to be highest near an active source of emanating fluid in both habitats. Rate of recruitment at vents is more variable among studies within a segment than among segments. Across different chemosynthetic habitats, recruitment rate of bivalves is much more variable than that of gastropods and polychaetes. Total recruitment rate ranges only between 0.1 and 1 ind dm−2 d−1 across all chemosynthetic habitats, falling above rates in the non-reducing deep sea. The recruit assemblages at vents, seeps and kelp falls have lower taxonomic breadth, and include more families and genera that have many species more closely related to each other than those at whale and wood falls. Vents also

  18. Lineage-associated tracts defining the anatomy of the Drosophila first instar larval brain.

    PubMed

    Hartenstein, Volker; Younossi-Hartenstein, Amelia; Lovick, Jennifer K; Kong, Angel; Omoto, Jaison J; Ngo, Kathy T; Viktorin, Gudrun

    2015-10-01

    Fixed lineages derived from unique, genetically specified neuroblasts form the anatomical building blocks of the Drosophila brain. Neurons belonging to the same lineage project their axons in a common tract, which is labeled by neuronal markers. In this paper, we present a detailed atlas of the lineage-associated tracts forming the brain of the early Drosophila larva, based on the use of global markers (anti-Neuroglian, anti-Neurotactin, inscuteable-Gal4>UAS-chRFP-Tub) and lineage-specific reporters. We describe 68 discrete fiber bundles that contain axons of one lineage or pairs/small sets of adjacent lineages. Bundles enter the neuropil at invariant locations, the lineage tract entry portals. Within the neuropil, these fiber bundles form larger fascicles that can be classified, by their main orientation, into longitudinal, transverse, and vertical (ascending/descending) fascicles. We present 3D digital models of lineage tract entry portals and neuropil fascicles, set into relationship to commonly used, easily recognizable reference structures such as the mushroom body, the antennal lobe, the optic lobe, and the Fasciclin II-positive fiber bundles that connect the brain and ventral nerve cord. Correspondences and differences between early larval tract anatomy and the previously described late larval and adult lineage patterns are highlighted. Our L1 neuro-anatomical atlas of lineages constitutes an essential step towards following morphologically defined lineages to the neuroblasts of the early embryo, which will ultimately make it possible to link the structure and connectivity of a lineage to the expression of genes in the particular neuroblast that gives rise to that lineage. Furthermore, the L1 atlas will be important for a host of ongoing work that attempts to reconstruct neuronal connectivity at the level of resolution of single neurons and their synapses. PMID:26141956

  19. Comparison of population-genetic structuring in congeneric kelp- versus rock-associated snails: a test of a dispersal-by-rafting hypothesis

    PubMed Central

    Nikula, Raisa; Spencer, Hamish G; Waters, Jonathan M

    2011-01-01

    Phylogeographic studies indicate that many marine invertebrates lacking autonomous dispersal ability are able to achieve trans-oceanic colonization by rafting on buoyant macroalgae. However, less is known about the impact of rafting on on-going population-genetic connectivity of intertidal species associated with buoyant macroalgae. We hypothesize that such species will have higher levels of population-genetic connectivity than those exploiting nonbuoyant substrates such as rock. We tested this hypothesis by comparing nuclear multilocus population-genetic structuring in two sister topshell species, which both have a planktonic larval phase but are fairly well segregated by their habitat preference of low-tidal bull-kelp holdfasts versus mid-to-low tidal bare rock. We analyzed population samples from four sympatric sites spanning 372 km of the east coast of southern New Zealand. The sampled region encompasses a 180 km wide habitat discontinuity and is influenced by a stable, northward coastal current. The level of connectivity was high in both species, and neither of them showed significant correlation between genetic and geographic distances. However, a significant negative partial correlation between genetic distance and habitat discontinuity was found in the rock-associated species, and estimates of migrant movement between sites were somewhat different between the two species, with the kelp-associated species more often yielding higher estimates across the habitat discontinuity, whereas the rock-associated species more often exhibited higher estimates between sites interspersed by rock habitats. We conclude that for species with substantial means of autonomous dispersal, the most conspicuous consequence of kelp dwelling may be enhanced long-distance dispersal across habitat discontinuities rather than a general increase of gene flow. PMID:22393493

  20. The Effects of Anthropogenic Structures on Habitat Connectivity and the Potential Spread of Non-Native Invertebrate Species in the Offshore Environment

    PubMed Central

    Simons, Rachel D.; Page, Henry M.; Zaleski, Susan; Miller, Robert; Dugan, Jenifer E.; Schroeder, Donna M.; Doheny, Brandon

    2016-01-01

    Offshore structures provide habitat that could facilitate species range expansions and the introduction of non-native species into new geographic areas. Surveys of assemblages of seven offshore oil and gas platforms in the Santa Barbara Channel revealed a change in distribution of the non-native sessile invertebrate Watersipora subtorquata, a bryozoan with a planktonic larval duration (PLD) of 24 hours or less, from one platform in 2001 to four platforms in 2013. We use a three-dimensional biophysical model to assess whether larval dispersal via currents from harbors to platforms and among platforms is a plausible mechanism to explain the change in distribution of Watersipora and to predict potential spread to other platforms in the future. Hull fouling is another possible mechanism to explain the change in distribution of Watersipora. We find that larval dispersal via currents could account for the increase in distribution of Watersipora from one to four platforms and that Watersipora is unlikely to spread from these four platforms to additional platforms through larval dispersal. Our results also suggest that larvae with PLDs of 24 hours or less released from offshore platforms can attain much greater dispersal distances than larvae with PLDs of 24 hours or less released from nearshore habitat. We hypothesize that the enhanced dispersal distance of larvae released from offshore platforms is driven by a combination of the offshore hydrodynamic environment, larval behavior, and larval release above the seafloor. PMID:27031827

  1. The Effects of Anthropogenic Structures on Habitat Connectivity and the Potential Spread of Non-Native Invertebrate Species in the Offshore Environment.

    PubMed

    Simons, Rachel D; Page, Henry M; Zaleski, Susan; Miller, Robert; Dugan, Jenifer E; Schroeder, Donna M; Doheny, Brandon

    2016-01-01

    Offshore structures provide habitat that could facilitate species range expansions and the introduction of non-native species into new geographic areas. Surveys of assemblages of seven offshore oil and gas platforms in the Santa Barbara Channel revealed a change in distribution of the non-native sessile invertebrate Watersipora subtorquata, a bryozoan with a planktonic larval duration (PLD) of 24 hours or less, from one platform in 2001 to four platforms in 2013. We use a three-dimensional biophysical model to assess whether larval dispersal via currents from harbors to platforms and among platforms is a plausible mechanism to explain the change in distribution of Watersipora and to predict potential spread to other platforms in the future. Hull fouling is another possible mechanism to explain the change in distribution of Watersipora. We find that larval dispersal via currents could account for the increase in distribution of Watersipora from one to four platforms and that Watersipora is unlikely to spread from these four platforms to additional platforms through larval dispersal. Our results also suggest that larvae with PLDs of 24 hours or less released from offshore platforms can attain much greater dispersal distances than larvae with PLDs of 24 hours or less released from nearshore habitat. We hypothesize that the enhanced dispersal distance of larvae released from offshore platforms is driven by a combination of the offshore hydrodynamic environment, larval behavior, and larval release above the seafloor. PMID:27031827

  2. Simultaneous exposure to chronic hypoxia and dissolved polycyclic aromatic hydrocarbons results in reduced egg production and larval survival in the sheepshead minnow (Cyprinodon variegatus).

    PubMed

    Hedgpeth, Bryan M; Griffitt, Robert J

    2016-03-01

    Estuarine fish in the northern Gulf of Mexico are exposed annually to hypoxic conditions. In addition to hypoxia, fish located throughout the northern Gulf of Mexico were potentially exposed to oil released during the Deepwater Horizon incident. Therefore, the interaction between oil exposure and hypoxia is worth investigating. To examine this interaction, the authors exposed adult and larval sheepshead minnow (Cyprinodon variegatus) to crude or dispersed oil under both normoxic and hypoxic conditions. The authors examined total egg production, egg hatching success, and larval survival post hatch. The authors' results indicate that co-exposure to crude or dispersed oil and hypoxia resulted in a significant decrease in egg production, as well as a significant decrease in both egg hatch success and larval survival post hatch. The significant impact on reproductive success following crude or dispersed oil and hypoxia exposure indicates the importance of including environmental parameters such as hypoxia when evaluating the impact of an oil spill. Environ Toxicol Chem 2016;35:645-651. © 2015 SETAC. PMID:26274940

  3. Strong population genetic structure and larval dispersal capability of the burrowing ghost shrimp (Neotrypaea californiensis)

    EPA Science Inventory

    The burrowing ghost shrimp, Neotrypaea californiensis, is a vital member of the estuarine benthic community. Dense populations of shrimp are found in the major estuaries of Washington and Oregon. Our study determines the genetic structure of shrimp populations in order to gain ...

  4. Transmembrane channel-like (tmc) gene regulates Drosophila larval locomotion.

    PubMed

    Guo, Yanmeng; Wang, Yuping; Zhang, Wei; Meltzer, Shan; Zanini, Damiano; Yu, Yue; Li, Jiefu; Cheng, Tong; Guo, Zhenhao; Wang, Qingxiu; Jacobs, Julie S; Sharma, Yashoda; Eberl, Daniel F; Göpfert, Martin C; Jan, Lily Yeh; Jan, Yuh Nung; Wang, Zuoren

    2016-06-28

    Drosophila larval locomotion, which entails rhythmic body contractions, is controlled by sensory feedback from proprioceptors. The molecular mechanisms mediating this feedback are little understood. By using genetic knock-in and immunostaining, we found that the Drosophila melanogaster transmembrane channel-like (tmc) gene is expressed in the larval class I and class II dendritic arborization (da) neurons and bipolar dendrite (bd) neurons, both of which are known to provide sensory feedback for larval locomotion. Larvae with knockdown or loss of tmc function displayed reduced crawling speeds, increased head cast frequencies, and enhanced backward locomotion. Expressing Drosophila TMC or mammalian TMC1 and/or TMC2 in the tmc-positive neurons rescued these mutant phenotypes. Bending of the larval body activated the tmc-positive neurons, and in tmc mutants this bending response was impaired. This implicates TMC's roles in Drosophila proprioception and the sensory control of larval locomotion. It also provides evidence for a functional conservation between Drosophila and mammalian TMCs. PMID:27298354

  5. Local scale connectivity in the cave-dwelling brooding fish Apogon imberbis

    NASA Astrophysics Data System (ADS)

    Muths, Delphine; Rastorgueff, Pierre-Alexandre; Selva, Marjorie; Chevaldonné, Pierre

    2015-01-01

    A lower degree of population connectivity is generally expected for species living in a naturally fragmented habitat than for species living in a continuum of suitable environment. Due to clear-cut environmental conditions with the surrounding littoral zone, underwater marine caves of the Mediterranean Sea constitute a good model to explore the effect of habitat discontinuity on the population structure of their inhabitants. With this goal, the genetic population structure of Apogon imberbis, a mouth-brooding teleost, was explored using the mitochondrial cytochrome b gene and 7 nuclear microsatellite loci from 164 fishes sampled at the micro-scale (ca. 40 km) of the Marseille area (Bay of Marseille and Calanques coast, in NW Mediterranean). Both marker types indicated a low level of genetic structure within the studied area. We propose that each suitable crack and cavity is used as a stepping-stone habitat between disconnected large cave-habitats. This, together with larval dispersal, ensures enough gene flow between caves to homogenize the genetic pattern at microscale while isolation by distance and by open waters could explain the small structure observed. The present study indicates that the effect of natural fragmentation in connectivity disruption can largely be counter-balanced by life history traits and overlooked details in habitat preferences.

  6. Spatial and temporal influences on hydrologic connectivity: A mathematical formalization

    EPA Science Inventory

    Connectivity between landscape elements has been an important consideration in landscape ecology since at least the mid-1980s. In particular, the use of random landscapes to study the interaction between connectivity, landscape structure, and dispersal mechanisms has provided in...

  7. Particle motion is broadly represented in the vestibular medulla of the bullfrog across larval development.

    PubMed

    Simmons, Andrea Megela; Flores, Victoria

    2012-04-01

    In their shallow-water habitats, bullfrog (Rana catesbeiana) tadpoles are exposed to both underwater and airborne sources of acoustic stimulation. We probed the representation of underwater particle motion throughout the tadpole's dorsal medulla to determine its spatial extent over larval life. Using neurobiotin-filled micropipettes, we recorded neural activity to z-axis particle motion (frequencies of 40-200 Hz) in the medial vestibular nucleus, lateral vestibular nucleus, dorsal medullary nucleus (DMN), and along the dorsal arcuate pathway. Sensitivity was comparable in the medial and lateral vestibular nuclei, with estimated thresholds between 0.016 and 12.5 μm displacement. Neither best responding frequency nor estimated threshold varied significantly over larval stage. Transport of neurobiotin from active recording sites was also stable over development. The DMN responded poorly to z-axis particle motion, but did respond to low-frequency pressure stimulation. These data suggest that particle motion is represented widely and stably in the tadpole's vestibular medulla. This is in marked contrast to the representation of pressure stimulation in the auditory midbrain, where a transient "deaf period" of non-responsiveness and decreased connectivity occurs immediately prior to metamorphic climax. We suggest that, in bullfrogs, sensitivity to particle motion and to pressure follows different developmental trajectories. PMID:22198742

  8. Egg hatching, larval movement and larval survival of the malaria vector Anopheles gambiae in desiccating habitats

    PubMed Central

    Koenraadt, Constantianus JM; Paaijmans, Krijn P; Githeko, Andrew K; Knols, Bart GJ; Takken, Willem

    2003-01-01

    Background Although the effects of rainfall on the population dynamics of the malaria vector Anopheles gambiae have been studied in great detail, the effects of dry periods on its survival remain less clear. Methods The effects of drying conditions were simulated by creating desiccated habitats, which consisted of trays filled with damp soil. Experiments were performed in these trays to (i) test the ability of An. gambiae sensu stricto eggs to hatch on damp soil and for larvae to reach an artificial breeding site at different distances of the site of hatching and (ii) to record survival of the four larval stages of An. gambiae s.s. when placed on damp soil. Results Eggs of An. gambiae s.s. hatched on damp soil and emerging larvae were capable of covering a distance of up to 10 cm to reach surface water enabling further development. However, proportions of larvae reaching the site decreased rapidly with increasing distance. First, second and third-instar larvae survived on damp soil for an estimated period of 64, 65 and 69 hrs, respectively. Fourth-instar larvae survived significantly longer and we estimated that the maximum survival time was 113 hrs. Conclusion Short-term survival of aquatic stages of An. gambiae on wet soil may be important and adaptive when considering the transient nature of breeding sites of this species in sub-Saharan Africa. In addition, the results suggest that, for larval vector control methods to be effective, habitats should remain drained for at least 5 days to kill all larvae (e.g. in rice fields) and habitats that recently dried up should be treated as well, if larvicidal agents are applied. PMID:12919636

  9. Phormidium animalis (Cyanobacteria: Oscillatoriaceae) supports larval development of Anopheles albimanus.

    PubMed

    Vázquez-Martínez, M Guadalupe; Rodríguez, Mario H; Arredondo-Jiménez, Juan I; Méndez-Sánchez, José D

    2003-06-01

    The capability of Phormidium animalis, a cyanobacterium commonly found in larval habitats of Anopheles albimanus in southern Mexico, to support larval development of this mosquito was investigated. First-stage larvae were reared under insectary conditions with P. animalis ad libitum and their development was compared with larvae fed with wheat germ. The time of pupation and adult mosquito size, assessed by wing length, were similar in both groups, but fewer adult mosquitoes were obtained from larvae fed with the cyanobacteria. Nevertheless, these observations indicate that P. animalis is ingested and assimilated by larval An. albimanus, making this cyanobacterium a good candidate for genetic engineering for the introduction of mosquitocidal toxins for malaria control in the region. PMID:12825668

  10. Measurement of Larval Activity in the Drosophila Activity Monitor

    PubMed Central

    McParland, Aidan L.; Follansbee, Taylor L.; Ganter, Geoffrey K.

    2016-01-01

    Drosophila larvae are used in many behavioral studies, yet a simple device for measuring basic parameters of larval activity has not been available. This protocol repurposes an instrument often used to measure adult activity, the TriKinetics Drosophila activity monitor (MB5 Multi-Beam Activity Monitor) to study larval activity. The instrument can monitor the movements of animals in 16 individual 8 cm glass assay tubes, using 17 infrared detection beams per tube. Logging software automatically saves data to a computer, recording parameters such as number of moves, times sensors were triggered, and animals’ positions within the tubes. The data can then be analyzed to represent overall locomotion and/or position preference as well as other measurements. All data are easily accessible and compatible with basic graphing and data manipulation software. This protocol will discuss how to use the apparatus, how to operate the software and how to run a larval activity assay from start to finish. PMID:25993121

  11. Effects of climate change on the survival of larval cod

    NASA Astrophysics Data System (ADS)

    Kristiansen, T.; Stock, C. A.; Drinkwater, K. F.; Curchitser, E. N.

    2011-12-01

    Understanding how climate change may impact important commercial fisheries is critical for developing sustainable fisheries management strategies. In this study, we used simulations from an Earth System Model (NOAA GFDL ESM2.1) coupled with an individual-based model (IBM) for larval fish to provide a first assessment of the potential importance of climate-change driven changes in primary productivity and temperature on cod recruitment in the North Atlantic to the year 2100. ESM model output was averaged for 5 regions, each with an area of 5x5 on a latitude-longitude grid, and representing the geographic boundaries of the current cod range. The physical and environmental data were incorporated into a mechanistic IBM used to simulate the critical early phases in the life of larval fish (e.g. cod) in a changing environment. Large phytoplankton production was predicted to decrease in most regions, thereby lowering the number of meso-zooplankton in the water column. Meso-zooplankton is the most important prey item for larval cod and a reduction in their numbers have strong impacts on larval cod survival. The combination of lowered prey abundance with increased energy requirement for growth and metabolism through increased temperature had a negative impact on cod recruitment in all modeled regions of the North Atlantic. The probability of survival past the larval stages was reduced with 20-30% at all five spawning grounds by the year 2100. Together, these results suggest climate change could have significant impacts on the survival of larval cod in the North Atlantic.

  12. Adult beetles compensate for poor larval food conditions.

    PubMed

    Müller, Thorben; Müller, Caroline

    2016-05-01

    Life history traits of herbivores are highly influenced by the quality of their hosts, i.e., the composition of primary and secondary plant metabolites. In holometabolous insects, larvae and adults may face different host plants, which differ in quality. It has been hypothesised that adult fitness is either highest when larval and adult environmental conditions match (environmental matching) or it may be mainly determined by optimal larval conditions (silver spoon effect). Alternatively, the adult stage may be most decisive for the actual fitness, independent of larval food exposure, due to adult compensation ability. To determine the influence of constant versus changing larval and adult host plant experiences on growth performance, fitness and feeding preferences, we carried out a match-mismatch experiment using the mustard leaf beetle, Phaedon cochleariae. Larvae and adults were either constantly reared on watercress (natural host) or cabbage (crop plant) or were switched after metamorphosis to the other host. Growth, reproductive traits and feeding preferences were determined repeatedly over lifetime and host plant quality traits analysed. Differences in the host quality led to differences in the development time and female reproduction. Egg numbers were significantly influenced by the host plant species experienced by the adults. Thus, adults were able to compensate for poor larval conditions. Likewise, the current host experience was most decisive for feeding preferences; in adult beetles a feeding preference was shaped regardless of the larval host plant. Larvae or adults reared on the more nutritious host, cabbage, showed a higher preference for this host. Hence, beetles most likely develop a preference when gaining a direct positive feedback in terms of an improved performance, whereby the current experience matters the most. Highly nutritious crop plants may be, in consequence, all the more exploited by potential pests that may show a high plasticity in

  13. Effects of beach morphology and waves on onshore larval transport

    NASA Astrophysics Data System (ADS)

    Fujimura, A.; Reniers, A.; Paris, C. B.; Shanks, A.; MacMahan, J.; Morgan, S.

    2015-12-01

    Larvae of intertidal species grow offshore, and migrate back to the shore when they are ready to settle on their adult substrates. In order to reach the habitat, they must cross the surf zone, which is characterized as a semi-permeable barrier. This is accomplished through physical forcing (i.e., waves and current) as well as their own behavior. Two possible scenarios of onshore larval transport are proposed: Negatively buoyant larvae stay in the bottom boundary layer because of turbulence-dependent sinking behavior, and are carried toward the shore by streaming of the bottom boundary layer; positively buoyant larvae move to the shore during onshore wind events, and sink to the bottom once they encounter high turbulence (i.e., surf zone edge), where they are carried by the bottom current toward the shore (Fujimura et al. 2014). Our biophysical Lagrangian particle tracking model helps to explain how beach morphology and wave conditions affect larval distribution patterns and abundance. Model results and field observations show that larval abundance in the surf zone is higher at mildly sloped, rip-channeled beaches than at steep pocket beaches. Beach attributes are broken up to examine which and how beach configuration factors affect larval abundance. Modeling with alongshore uniform beaches with variable slopes reveal that larval populations in the surf zone are negatively correlated with beach steepness. Alongshore variability enhances onshore larval transport because of increased cross-shore water exchange by rip currents. Wave groups produce transient rip currents and enhance cross-shore exchange. Effects of other wave components, such as wave height and breaking wave rollers are also considered.

  14. Effects of coastal transport on larval patches: Models and observations

    NASA Astrophysics Data System (ADS)

    Tilburg, Charles E.; Houser, Letise T.; Steppe, Cecily N.; Garvine, Richard W.; Epifanio, Charles E.

    2006-03-01

    We used a combination of field observations and numerical modeling to examine the physical mechanisms responsible for the evolution and transport of patches of blue crab larvae in the mouth of Delaware Bay. The observations consisted of larval collections and surface salinity measurements taken along a moving spatial grid whose origin was determined by a satellite-tracked drifter. Examination of field observations revealed a slender larval patch that was aligned with salinity contours. Measurement of the salting rate of the larval patch indicated that the patch moved through the offshore edge of a buoyant plume due to wind-driven upwelling circulation. A numerical model that provided realistic simulations of the flow field at the mouth of Delaware Bay and the adjoining coastal ocean was used to examine the physical mechanisms responsible for the movement and evolution of the patch. We conducted a series of simulations in which we separately examined the effects of tides, buoyancy-driven flow, and wind-driven transport. Results showed that both tides and buoyancy-driven flow tend to elongate an initially square fluid element. Although winds alone have little effect on the shape of a patch, wind-driven flow can effectively move a patch through a complex flow field in which the deformation by tides and buoyancy-driven circulation can have significant effects. This study represents the first observation and analysis of a larval patch that remains intact while moving through the edge of a buoyant plume. It provides new insight into the shape of larval patches in Delaware Bay and any region with strong buoyancy- and tidally-driven flow, suggesting that typical larval patches may not be characterized by equal across- and alongshelf dimensions but instead tend to be slender shapes that are aligned with the flow field.

  15. Larval nematodes found in amphibians from northeastern Argentina.

    PubMed

    González, C E; Hamann, M I

    2010-11-01

    Five species of amphibians, Leptodactylus podicipinus, Scinax acuminatus, S. nasicus, Rhinella fernandezae and Pseudis paradoxa, were collected in Corrientes province, Argentina and searched for larval nematodes. All larval nematodes were found as cysts in the serous of the stomach of hosts. Were identified one superfamily, Seuratoidea; one genus, Spiroxys (Superfamily Gnathostomatoidea) and one family, Rhabdochonidae (Superfamily Thelazioidea). We present a description and illustrations of these taxa. These nematodes have an indirect life cycle and amphibians are infected by consuming invertebrate, the intermediate hosts. The genus Spiroxys and superfamily Seuratoidea were reported for the first time for Argentinean amphibians. PMID:21180919

  16. Effects of Underwater Turbine Noise on Crab Larval Metamorphosis.

    PubMed

    Pine, Matthew K; Jeffs, Andrew G; Radford, Craig A

    2016-01-01

    The development of marine tidal turbines has advanced at a rapid rate over the last decade but with little detailed understanding of the potential noise impacts on invertebrates. Previous research has shown that underwater reef noise plays an important role in mediating metamorphosis in many larval crabs and fishes. New research suggests that underwater estuarine noise may also mediate metamorphosis in estuarine crab larvae and that the noise emitted from underwater tidal and sea-based wind turbines may significantly influence larval metamorphosis in estuarine crabs. PMID:26611041

  17. A merganser die-off associated with larval eustrongylides

    USGS Publications Warehouse

    Locke, L.N.; DeWitt, J.B.; Menzie, C.M.; Kerwin, J.A.

    1964-01-01

    A die-off of red-breasted mergansers on Lake Holly, Virginia Beach, Virginia, was found to be due to a larval Eustrongylides. Massive tissue destruction and hemorrhage was produced by the migration of the larval Eustrongylides. Earlier stages of the same Eustrongylides were found in eastern mosquitofish and silversides upon which the mergansers had been feeding. In addition, residues of DDT were found in mosquitofish, gizzard shad, and five mergansers collected from Lake Holly, and in the tissues of two mergansers from Back Bay, Virginia. However, the information available was insufficient to establish the significance of these residue levels.

  18. Toxicity of the dispersant Corexit 9500 to early life stages of blue crab, Callinectes sapidus.

    PubMed

    Anderson Lively, Julie A; McKenzie, Jon

    2014-12-01

    The Deepwater Horizon well released 4.4 million barrels of light crude oil offshore of Louisiana into one of the world's largest and most productive blue crab (Callinectes sapidus) fisheries. The objectives of this paper were to determine the toxicity of the dispersant Corexit(®) 9500A used in the 2010 oil spill on juvenile and larval blue crabs, and the long-term effects of sublethal acute exposure. Only the highest treatment levels of dispersant significantly increased mortality in larval and juvenile blue crabs (100 mg/L and 1,000 mg/L, respectively). This correlated to concentrations well above levels found in the Gulf of Mexico following the spill. Smaller and younger crabs showed higher mortality than older and larger crabs. This research indicates direct application of dispersants on crab larvae could cause acute mortality, but dilution through diffusion and natural weathering processes would minimize long-term effects. PMID:25173366

  19. Population Genetics of a Trochid Gastropod Broadens Picture of Caribbean Sea Connectivity

    PubMed Central

    Díaz-Ferguson, Edgardo; Haney, Robert; Wares, John; Silliman, Brian

    2010-01-01

    Background Regional genetic connectivity models are critical for successful conservation and management of marine species. Even though rocky shore invertebrates have been used as model systems to understand genetic structure in some marine environments, our understanding of connectivity in Caribbean communities is based overwhelmingly on studies of tropical fishes and corals. In this study, we investigate population connectivity and diversity of Cittarium pica, an abundant rocky shore trochid gastropod that is commercially harvested across its natural range, from the Bahamas to Venezuela. Methodology/Principal Findings We tested for genetic structure using DNA sequence variation at the mitochondrial COI and 16S loci, AMOVA and distance-based methods. We found substantial differentiation among Caribbean sites. Yet, genetic differentiation was associated only with larger geographic scales within the Caribbean, and the pattern of differentiation only partially matched previous assessments of Caribbean connectivity, including those based on larval dispersal from hydrodynamic models. For instance, the Bahamas, considered an independent region by previous hydrodynamic studies, showed strong association with Eastern Caribbean sites in our study. Further, Bonaire (located in the east and close to the meridional division of the Caribbean basin) seems to be isolated from other Eastern sites. Conclusions/Significance The significant genetic structure and observed in C. pica has some commonalities in pattern with more commonly sampled taxa, but presents features, such as the differentiation of Bonaire, that appear unique. Further, the level of differentiation, together with regional patterns of diversity, has important implications for the application of conservation and management strategies in this commercially harvested species. PMID:20844767

  20. Aspects of larval, post-larval and juvenile ecology of Macrobrachium petersi (Hilgendorf) in the Keiskamma estuary, South Africa

    NASA Astrophysics Data System (ADS)

    Read, G. H. L.

    1985-10-01

    Although Macrobrachium petersi has nine larval stages, only stage I and a minimal number of stage II M. petersi larvae were caught in the Keiskamma estuary. Stage I larvae undergo a vertical migration at night which is markedly influenced by salinity, especially under stratified conditions. Larvae remain in the water column on the ebb tide, a behavioural pattern which effectively carried them to favourable salinities for growth and development. Stage I larvae show an association with salt front regions. The sudden decline in larval abundance from stage I to stage II downstream from the front suggests a change from a pelagic to an epibenthic existence. Later larval stages failed to appear in the plankton. However, post-larvae were caught in the estuary and a juvenile migration from the estuary to freshwater was monitored.

  1. The Great Melting Pot. Common Sole Population Connectivity Assessed by Otolith and Water Fingerprints

    PubMed Central

    Morat, Fabien; Letourneur, Yves; Dierking, Jan; Pécheyran, Christophe; Bareille, Gilles; Blamart, Dominique; Harmelin-Vivien, Mireille

    2014-01-01

    Quantifying the scale and importance of individual dispersion between populations and life stages is a key challenge in marine ecology. The common sole (Solea solea), an important commercial flatfish in the North Sea, Atlantic Ocean and the Mediterranean Sea, has a marine pelagic larval stage, a benthic juvenile stage in coastal nurseries (lagoons, estuaries or shallow marine areas) and a benthic adult stage in deeper marine waters on the continental shelf. To date, the ecological connectivity among these life stages has been little assessed in the Mediterranean. Here, such an assessment is provided for the first time for the Gulf of Lions, NW Mediterranean, based on a dataset on otolith microchemistry and stable isotopic composition as indicators of the water masses inhabited by individual fish. Specifically, otolith Ba/Ca and Sr/Ca profiles, and δ13C and δ18O values of adults collected in four areas of the Gulf of Lions were compared with those of young-of-the-year collected in different coastal nurseries. Results showed that a high proportion of adults (>46%) were influenced by river inputs during their larval stage. Furthermore Sr/Ca ratios and the otolith length at one year of age revealed that most adults (∼70%) spent their juvenile stage in nurseries with high salinity, whereas the remainder used brackish environments. In total, data were consistent with the use of six nursery types, three with high salinity (marine areas and two types of highly saline lagoons) and three brackish (coastal areas near river mouths, and two types of brackish environments), all of which contributed to the replenishment of adult populations. These finding implicated panmixia in sole population in the Gulf of Lions and claimed for a habitat integrated management of fisheries. PMID:24475151

  2. Making Connections

    ERIC Educational Resources Information Center

    Turner, Paul

    2015-01-01

    This article aims to illustrate a process of making connections, not between mathematics and other activities, but within mathematics itself--between diverse parts of the subject. Novel connections are still possible in previously explored mathematics when the material happens to be unfamiliar, as may be the case for a learner at any career stage.…

  3. HABITAT ASSOCIATIONS OF LARVAL FISH IN A LAKE SUPERIOR COASTAL WETLAND

    EPA Science Inventory

    Habitat associations of larval fishes in Great Lakes coastal wetlands (GLCW) are not well documented. To determine the distribution of larval fish in coastal wetlands with regard to location and vegetation characteristics, we used a larval tow-sled to sample four macrohabitat typ...

  4. Dispersal of a defensive symbiont depends on contact between hosts, host health, and host size.

    PubMed

    Hopkins, Skylar R; Boyle, Lindsey J; Belden, Lisa K; Wojdak, Jeremy M

    2015-10-01

    Symbiont dispersal is necessary for the maintenance of defense mutualisms in space and time, and the distribution of symbionts among hosts should be intricately tied to symbiont dispersal behaviors. However, we know surprisingly little about how most defensive symbionts find and choose advantageous hosts or what cues trigger symbionts to disperse from their current hosts. In a series of six experiments, we explored the dispersal ecology of an oligochaete worm (Chaetogaster limnaei) that protects snail hosts from infection by larval trematode parasites. Specifically, we determined the factors that affected net symbiont dispersal from a current "donor" host to a new "receiver" host. Symbionts rarely dispersed unless hosts directly came in contact with one another. However, symbionts overcame their reluctance to disperse across the open environment if the donor host died. When hosts came in direct contact, net symbiont dispersal varied with both host size and trematode infection status, whereas symbiont density did not influence the probability of symbiont dispersal. Together, these experiments show that symbiont dispersal is not a constant, random process, as is often assumed in symbiont dispersal models, but rather the probability of dispersal varies with ecological conditions and among individual hosts. The observed heterogeneity in dispersal rates among hosts may help to explain symbiont aggregation among snail hosts in nature. PMID:25964062

  5. Larval fish dynamics in spring pools in middle Tennessee

    USGS Publications Warehouse

    Bettoli, Phillip William; Goldsworthy, C.A.

    2011-01-01

    We used lighted larval traps to assess reproduction by fishes inhabiting nine spring pools in the Barrens Plateau region of middle Tennessee between May and September 2004. The traps (n = 162 deployments) captured the larval or juvenile forms of Etheostoma crossopterum (Fringed Darter) (n = 188), Gambusia affinis (Western Mosquitofish) (n = 139), Hemitremia flammea (Flame Chub) (n = 55), the imperiled Fundulus julisia (Barrens Topminnow) (n = 10), and Forbesichthys agassizii (Spring Cavefish) (n = 1). The larval forms of four other species (Families Centrarchidae, Cyprinidae, and Cottidae) were not collected, despite the presence of adults. Larval Barrens Topminnow hatched over a protracted period (early June through late September); in contrast, hatching intervals were much shorter for Fringed Darter (mid-May through early June). Flame Chub hatching began before our first samples in early May and concluded by late-May. Juvenile Western Mosquitofish were collected between early June and late August. Our sampling revealed that at least two species (Flame Chub and Fringed Darter) were able to reproduce and recruit in habitats harboring the invasive Western Mosquitofish, while Barrens Topminnow could not.

  6. Evolved differences in larval social behavior mediated by novel pheromones

    PubMed Central

    Mast, Joshua D; De Moraes, Consuelo M; Alborn, Hans T; Lavis, Luke D; Stern, David L

    2014-01-01

    Pheromones, chemical signals that convey social information, mediate many insect social behaviors, including navigation and aggregation. Several studies have suggested that behavior during the immature larval stages of Drosophila development is influenced by pheromones, but none of these compounds or the pheromone-receptor neurons that sense them have been identified. Here we report a larval pheromone-signaling pathway. We found that larvae produce two novel long-chain fatty acids that are attractive to other larvae. We identified a single larval chemosensory neuron that detects these molecules. Two members of the pickpocket family of DEG/ENaC channel subunits (ppk23 and ppk29) are required to respond to these pheromones. This pheromone system is evolving quickly, since the larval exudates of D. simulans, the sister species of D. melanogaster, are not attractive to other larvae. Our results define a new pheromone signaling system in Drosophila that shares characteristics with pheromone systems in a wide diversity of insects. DOI: http://dx.doi.org/10.7554/eLife.04205.001 PMID:25497433

  7. Fruit Fly Liquid Larval Diet Technology Transfer and Update

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Since October 2006, USDA-ARS has been implementing a fruit fly liquid larval diet technology transfer, which has proceeded according to the following steps: (1) Recruitment of interested groups through request; (2) Establishment of the Material Transfer Agreement (MTA) with ARS; (3) Fruit fly liquid...

  8. Phenology of larval fish in the St. Louis River estuary

    EPA Science Inventory

    Little work has been done on the phenology of fish larvae in Great Lakes coastal wetlands. As part of an aquatic invasive species early detection study, we conducted larval fish surveys in the St. Louis River estuary (SLRE) in 2012 and 2013. Using multiple gears in a spatially ba...

  9. LARVAL FISH HABITAT QUALITY : THE EFFECTS OF FRESHWATER FLOW

    EPA Science Inventory

    We sampled larval fish in Suisun Marsh, in the San Francisco Bay estuary from February to June 1994-1999. We used principal components analysis (PCA) and canonical correspondence analysis (CCA) on 13 taxonomic groups making up 99.7% of the catch and several environmental variable...

  10. New larval trematodes in Biomphalaria species (Planorbidae) from Northeastern Argentina.

    PubMed

    Fernández, María Virginia; Hamann, Monika Inés; de Núñez, Margarita Ostrowski

    2016-09-01

    Larval trematodes infecting Biomphalaria tenagophila and B. occidentalis were surveyed in a suburban and semipermanent pond of Corrientes province, Northeastern Argentina. A total of 1,409 snails were examined between spring 2011 to winter 2013, and 8 different larval trematodes were studied morphologically. Three of these species-Echinocercaria sp. IV, Ribeiroia sp. and Echinocercaria sp. XIV-have been previously found in Corrientes province. Six other trematodes belonging to Strigeidae (Furcocercaria sp. III), Clinostomidae (Cercaria Clinostomidae sp.), Spirorchiidae (Cercaria Spirorchiidae sp.) and Echinostomatidae (Echinocercaria sp. 1, Echinocercaria sp. 2, Echinocercaria sp. 3) are new species parasitizing Biomphalaria snails. Cercaria Spirorchiidae sp. is the third larval trematode related to Spirorchiidae recorded in South America and the first one for Argentina. Cercaria Clinostomidae sp. is the first one related to Clinostomidae in northeastern Argentina. The prevalence of larval trematodes infecting B. tenagophila and B. occidentalis in the environment studied was low (<5%) with the echinostome group better represented in terms of prevalence and species richness. Drought periods could affect the dynamics of parasitic transmission due to the absence of trematodes in the autumn and winter of the first seasonal cycle. However, in humid periods parasite transmission can occur throughout the year due to the presence of larvae in all seasons of the second seasonal cycle, although the less-warm seasons showed higher prevalence than the summer period probably related to the subtropical climate of Corrientes province. PMID:27447210

  11. Rainbow smelt - larval lake herring interactions: competitors or casual acquaintances?

    USGS Publications Warehouse

    Selgeby, James H.; MacCallum, Wayne R.; Hoff, Michael H.

    1994-01-01

    We examined the hypothesis that competition for food between rainbow smelt (Osmerus mordax) and larval lake herring (Coregonus artedi) was a cause for the declines of lake herring stocks in Lake Superior. We studied the diet of larval lake herring and of larval, juvenile, and adult rainbow smelt during 1974 in Black Bay, Ontario, where both species were abundant, and in the Apostle Islands Region, Wisconsin, where rainbow smelt was abundant but lake herring was scarce. No evidence of competition for food was found between larval lake herring and rainbow smelt. Spawning and hatching times of the two species were separate enough that most larvae of the two species did not occupy the study areas simultaneously. Juvenile and adult rainbow smelt were found with lake herring larvae, but their diets differed. Therefore, we concluded that rainbow smelt did not compete with lake herring larvae for food and that competition for food between rainbow smelt and lake herring larvae was not the factor that caused lake herring population declines in Lake Superior.

  12. A sampler for capturing larval and juvenile Atlantic menhaden

    USGS Publications Warehouse

    Hedrick, J.D.; Hedrick, L.R.; Margraf, F.J.

    2005-01-01

    Interest in capturing larval and juvenile Atlantic menhaden Brevoortia tyrannus for use in laboratory studies required the design and construction of a sampling device that would allow us to make collections of live fish from open-water areas. Our device for capturing 1-2.5-in larval-juvenile fish was constructed of a stainless steel frame that supported a 9.84-ft-long (3-m-long)5 cone plankton net with a 3.28-ft-diameter (1-m-diameter) opening and a 0.04-in (1-mm) mesh size. Although the plankton net was similar to that used during typical larval fish collections, the cod end was constructed of Plexiglas and was nearly watertight; this prevented impingement and injury to larval fish and provided a calm-water environment. The cod end was designed for quick release from the plankton net, and the entire cod end could be submerged into a 75-gal onboard holding tank. This design and technique obviated the netting or emerging of fish from the water until they were returned to the laboratory. ?? Copyright by the American Fisheries Society 2005.

  13. LARVAL DEVELOPMENT OF THE SPIDER CRAB, 'LIBINIA EMERGINATA' (MAJIDAE)

    EPA Science Inventory

    Larval development of the spider crab, Libinia emarginata, consists of two zoeal stages and megalopa. Laboratory-reared larvae (South Carolina and Rhode Island) are described and compared with planktonic larvae from Narragansett Bay, RI. No significant variations in morphology we...

  14. Swimming behavior of larval Medaka fish under microgravity

    NASA Astrophysics Data System (ADS)

    Furukawa, R.; Ijiri, K.

    Fish exhibit looping and rolling behaviors when subjected to short periods of microgravity during parabolic flight. Strain-differences in the behavioral response of adult Medaka fish ( Oryzias latipes) were reported previously, however, there have been few studies of larval fish behavior under microgravity. In the present study, we investigated whether microgravity affects the swimming behavior of larvae at various ages (0 to 20 days after hatching), using different strains: HNI-II, HO5, ha strain, and variety of different strains (variety). The preliminary experiments were done in the ground laboratory: the development of eyesight was examined using optokinetic response for the different strains. The visual acuity of larvae improved drastically during 20 days after hatching. Strain differences of response were noted for the development of their visual acuity. In microgravity, the results were significantly different from those of adult Medaka. The larval fish appeared to maintain their orientation, except that a few of them exhibited looping and rolling behavior. Further, most larvae swam normally with their backs turning toward the light source (dorsal light response, DLR), and the rest of them stayed with their abdomen touching the surface of the container (ventral substrate response, VSR). For larval stages, strain-differences and age-differences in behavior were observed, but less pronounced than with adult fish under microgravity. Our observations suggest that adaptability of larval fish to the gravitational change and the mechanism of their postural control in microgravity are more variable than in adult fish.

  15. Managing Ammonia Emissions From Screwworm Larval Rearing Media.

    PubMed

    Sagel, Agustin; Phillips, Pamela; Chaudhury, Muhammad; Skoda, Steven

    2016-02-01

    Mass production, sterilization, and release of screwworms (Cochliomyia hominivorax (Coquerel)) that were competitive in the field significantly contributed to the successful application of the sterile insect technique for eradication of screwworms from continental North America. Metabolic byproducts resulting from protein-rich diets required for larval screwworms lead to ammonia liberation, sometimes at high levels, within the mass rearing facility. Until recently a sodium polyacrylate gel bulking agent was used for the larval media and adsorbed much of the ammonia. A need to replace the gel with an environmentally "friendly" bulking agent, while not increasing ammonia levels in the rearing facility, led to a series of experiments with the objective of developing procedures to reduce ammonia emissions from the larval media bulked with cellulose fiber. Additives of ammonia-converting bacteria, potassium permanganate, and Yucca schidigera Roezl ex Otrgies powder extract, previously reported to reduce ammonia levels in organic environments, were evaluated. Ammonia-converting bacteria did not have a positive effect. Addition of Y. schidigera powder extract (∼1% of total volume), potassium permanganate (∼250 ppm), and a combination of these two additives (at these same concentrations) kept ammonia at equivalent levels as when larval media was bulked with gel. Potassium permanganate also had sufficient antimicrobial properties that the use of formaldehyde in the diet was not necessary. Further testing is needed, at a mass rearing level, before full implementation into the screwworm eradication program. PMID:26468514

  16. Effects of Vegetation Microclimate on Larval Cattle Fever Tick Survival

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cattle Fever Ticks (CFT), Rhipicephalus annulatus and R. microplus, have been a threat to the livestock industry for many years. These ticks are vectors of cattle fever, a disease produced by the hemoparasite Babesia bovis and B. bigemina. Laboratory research on CFT larval survival has shown that co...

  17. Stretch-activated cation channel from larval bullfrog skin.

    PubMed

    Hillyard, Stanley D; Willumsen, Niels J; Marrero, Mario B

    2010-05-01

    Cell-attached patches from isolated epithelial cells from larval bullfrog skin revealed a cation channel that was activated by applying suction (-1 kPa to -4.5 kPa) to the pipette. Activation was characterized by an initial large current spike that rapidly attenuated to a stable value and showed a variable pattern of opening and closing with continuing suction. Current-voltage plots demonstrated linear or inward rectification and single channel conductances of 44-56 pS with NaCl or KCl Ringer's solution as the pipette solution, and a reversal potential (-V(p)) of 20-40 mV. The conductance was markedly reduced with N-methyl-D-glucamide (NMDG)-Cl Ringer's solution in the pipette. Neither amiloride nor ATP, which are known to stimulate an apical cation channel in Ussing chamber preparations of larval frog skin, produced channel activation nor did these compounds affect the response to suction. Stretch activation was not affected by varying the pipette concentrations of Ca(2+) between 0 mmol l(-1) and 4 mmol l(-1) or by varying pH between 6.8 and 8.0. However, conductance was reduced with 4 mmol l(-1) Ca(2+). Western blot analysis of membrane homogenates from larval bullfrog and larval toad skin identified proteins that were immunoreactive with mammalian TRPC1 and TRPC5 (TRPC, canonical transient receptor potential channel) antibodies while homogenates of skin from newly metamorphosed bullfrogs were positive for TRPC1 and TRPC3/6/7 antibodies. The electrophysiological response of larval bullfrog skin resembles that of a stretch-activated cation channel characterized in Xenopus oocytes and proposed to be TRPC1. These results indicate this channel persists in all life stages of anurans and that TRP isoforms may be important for sensory functions of their skin. PMID:20435829

  18. Remotely Sensing Larval Population Dynamics of Rice Field Anophelines

    NASA Technical Reports Server (NTRS)

    Beck, Louisa R.; Dister, Sheri W.; Wood, Byron L.; Washino, Robert K.

    1997-01-01

    The primary objective of both studies was to determine if RS and GIS techniques could be used to distinguish between high and low larval-producing rice fields in California. Results of the first study suggested that early-season green-up and proximity to livestock pastures were positively correlated with high larval abundance. Based on the early-season spectral differences between high and low larval-producing fields, it appeared that canopy development and tillering influenced mosquito habitat quality. At that time, rice fields consisted of a mixture of plants and water, a combination that allowed An. freeborni females to lay eggs in partial sunlight, protected from both predators and wind. This established a population earlier in the season than in other, 'less-green' fields where tillering and plant emergence was too minimal for ovipositioning. The study also indicated the importance of the distance that a mosquito would have to fly in order to take a bloodmeal prior to ovipositing. These associations were fully explored in an expanded study two years later. The second study confirmed the positive relationship between early season canopy development and larval abundance, and also demonstrated the relationship between abundance and distance-to-pasture. The association between greenness (as measured using NDVI), distance-to-pasture, and abundance is illustrated. The second study also indicated the siginificance of the landscape context of rice fields for larval production. Fields that included opportunities for feeding and resting within the flight range of the mosquito had higher abundances than did fields that were in a homogeneous rice area.

  19. Food selection in larval fruit flies: dynamics and effects on larval development

    NASA Astrophysics Data System (ADS)

    Schwarz, Sebastian; Durisko, Zachary; Dukas, Reuven

    2014-01-01

    Selecting food items and attaining a nutritionally balanced diet is an important challenge for all animals including humans. We aimed to establish fruit fly larvae ( Drosophila melanogaster) as a simple yet powerful model system for examining the mechanisms of specific hunger and diet selection. In two lab experiments with artificial diets, we found that larvae deprived of either sucrose or protein later selectively fed on a diet providing the missing nutrient. When allowed to freely move between two adjacent food patches, larvae surprisingly preferred to settle on one patch containing yeast and ignored the patch providing sucrose. Moreover, when allowed to move freely between three patches, which provided either yeast only, sucrose only or a balanced mixture of yeast and sucrose, the majority of larvae settled on the yeast-plus-sucrose patch and about one third chose to feed on the yeast only food. While protein (yeast) is essential for development, we also quantified larval success on diets with or without sucrose and show that larvae develop faster on diets containing sucrose. Our data suggest that fruit fly larvae can quickly assess major nutrients in food and seek a diet providing a missing nutrient. The larvae, however, probably prefer to quickly dig into a single food substrate for enhanced protection over achieving an optimal diet.

  20. About connections.

    PubMed

    Rockland, Kathleen S

    2015-01-01

    Despite the attention attracted by "connectomics", one can lose sight of the very real questions concerning "What are connections?" In the neuroimaging community, "structural" connectivity is ground truth and underlying constraint on "functional" or "effective" connectivity. It is referenced to underlying anatomy; but, as increasingly remarked, there is a large gap between the wealth of human brain mapping and the relatively scant data on actual anatomical connectivity. Moreover, connections have typically been discussed as "pairwise", point x projecting to point y (or: to points y and z), or more recently, in graph theoretical terms, as "nodes" or regions and the interconnecting "edges". This is a convenient shorthand, but tends not to capture the richness and nuance of basic anatomical properties as identified in the classic tradition of tracer studies. The present short review accordingly revisits connectional weights, heterogeneity, reciprocity, topography, and hierarchical organization, drawing on concrete examples. The emphasis is on presynaptic long-distance connections, motivated by the intention to probe current assumptions and promote discussions about further progress and synthesis. PMID:26042001

  1. On the mathematics underlying dispersion relations

    NASA Astrophysics Data System (ADS)

    Labuda, Cecille; Labuda, Iwo

    2014-12-01

    The history of mathematical methods underlying the study of dispersion relations in physics is discussed. In particular, some misconceptions connected with a theorem known in the physics literature as Titchmarsh's Theorem are addressed. It is pointed out that the aforementioned theorem is a compilation of two well-known theorems in mathematics, the Paley-Wiener theorem and the Marcel Riesz theorem.

  2. The influence of oceanographic fronts and early-life-history traits on connectivity among littoral fish species

    PubMed Central

    Galarza, Juan A.; Carreras-Carbonell, Josep; Macpherson, Enrique; Pascual, Marta; Roques, Severine; Turner, George F.; Rico, Ciro

    2009-01-01

    The spatial distribution of neutral genetic diversity is mainly influenced by barriers to dispersal. The nature of such barriers varies according to the dispersal means and capabilities of the organisms concerned. Although these barriers are often obvious on land, in the ocean they can be more difficult to identify. Determining the relative influence of physical and biotic factors on genetic connectivity remains a major challenge for marine ecologists. Here, we compare gene flow patterns of 7 littoral fish species from 6 families with a range of early-life-history traits sampled at the same geographic locations across common environmental discontinuities in the form of oceanic fronts in the Western Mediterranean. We show that these fronts represent major barriers to gene flow and have a strong influence on the population genetic structure of some fish species. We also found no significant relation between the early-life-history traits most commonly investigated (egg type, pelagic larval duration, and inshore-offshore spawning) and gene flow patterns, suggesting that other life-history factors should deserve attention. The fronts analyzed and the underlying physical mechanisms are not site-specific but common among the oceans, suggesting the generality of our findings. PMID:19164518

  3. Statistical dispersion relation for spatially broadband fields.

    PubMed

    Shan, Mingguang; Nastasa, Viorel; Popescu, Gabriel

    2016-06-01

    The dispersion relation is fundamental to a physical phenomenon that develops in both space and time. This equation connects the spatial and temporal frequencies involved in the dynamic process through the material constants. Electromagnetic plane waves propagating in homogeneous media are bound by simple dispersion relation, which sets the magnitude of the spatial frequency, k, as being proportional to the temporal frequency, ω, with the proportionality constant dependent on the refractive index, n, and the speed of light in vacuum, c. Here we show that, for spatially broadband fields, an analog dispersion relation can be derived, except in this case the k-vector variance is connected with the temporal frequency through the statistics of the refractive index fluctuations in the medium. We discuss how this relationship can be used to retrieve information about refractive index distributions in biological tissues. This result is particularly significant in measurements of angular light scattering and quantitative phase imaging of biological structures. PMID:27244396

  4. Embryonic, Larval, and Juvenile Development of the Sea Biscuit Clypeaster subdepressus (Echinodermata: Clypeasteroida)

    PubMed Central

    Vellutini, Bruno C.; Migotto, Alvaro E.

    2010-01-01

    Sea biscuits and sand dollars diverged from other irregular echinoids approximately 55 million years ago and rapidly dispersed to oceans worldwide. A series of morphological changes were associated with the occupation of sand beds such as flattening of the body, shortening of primary spines, multiplication of podia, and retention of the lantern of Aristotle into adulthood. To investigate the developmental basis of such morphological changes we documented the ontogeny of Clypeaster subdepressus. We obtained gametes from adult specimens by KCl injection and raised the embryos at 26C. Ciliated blastulae hatched 7.5 h after sperm entry. During gastrulation the archenteron elongated continuously while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larvae began to feed in 3 d and were 20 d old at metamorphosis; starved larvae died 17 d after fertilization. Postlarval juveniles had neither mouth nor anus nor plates on the aboral side, except for the remnants of larval spicules, but their bilateral symmetry became evident after the resorption of larval tissues. Ossicles of the lantern were present and organized in 5 groups. Each group had 1 tooth, 2 demipyramids, and 2 epiphyses with a rotula in between. Early appendages consisted of 15 spines, 15 podia (2 types), and 5 sphaeridia. Podial types were distributed in accordance to Lovén's rule and the first podium of each ambulacrum was not encircled by the skeleton. Seven days after metamorphosis juveniles began to feed by rasping sand grains with the lantern. Juveniles survived in laboratory cultures for 9 months and died with wide, a single open sphaeridium per ambulacrum, aboral anus, and no differentiated food grooves or petaloids. Tracking the morphogenesis of early juveniles is a necessary step to elucidate the developmental mechanisms of echinoid growth and important groundwork to clarify homologies between irregular urchins. PMID:20339592

  5. Larval behaviour and settlement cues of a brooding coral reef sponge

    NASA Astrophysics Data System (ADS)

    Abdul Wahab, M. A.; de Nys, R.; Whalan, S.

    2011-06-01

    Patterns of larval release, dispersal and settlement in sponges are poorly understood despite their significance in explaining adult ecology. Time of release, swimming speeds, phototaxis and vertical migration were quantified for larvae of the dictyoceratid sponge Coscinoderma matthewsi. The influence of cues associated with biofilms and coral rubble on larval settlement and metamorphosis was also measured. C. matthewsi is a brooding sponge and releases tufted parenchymellae larvae during the day. Upon release, larvae (>90%) have no phototactic response, maintaining their position at the water surface for 80 min ± 0 (mean ± SE) regardless of a light cue (natural daylight) before exhibiting negative phototaxis. At 28 h post-release, the majority of larvae (94.7% ± 6.1) exposed to light from the surface migrated to the bottom and assumed a demersal phase. Without light, larvae occupied the surface for up to 28 h post-release (89.3% ± 1.8) before migrating to the bottom. Larvae did not settle gregariously and began to settle and metamorphose after 28 h post-release without a cue. Settlement and metamorphosis were faster in the presence of a biofilm (settlement = 15.0% ± 8.7 and metamorphosis = 12.5% ± 9.5 at 28 h post-release), while the addition of coral rubble accelerated metamorphosis further (settlement = 10.0% ± 4.1 and metamorphosis = 27.5% ± 10.3 at 28 h post-release) compared to controls (sterile surfaces) (settlement = 0% and metamorphosis = 0% at 28 h post-release). However, both biofilms and coral rubble decrease total metamorphosis (control = 92.5% ± 4.8, biofilms = 67.5% ± 7.5 and coral rubble = 55.0% ± 13.2) due to mortality after 76 h post-release.

  6. Propagule size and dispersal costs mediate establishment success of an invasive species.

    PubMed

    Lange, Rolanda; Marshall, Dustin J

    2016-03-01

    Bio-invasions depend on the number and frequency of invaders arriving in new habitats. Yet, as is often the case, it is not only quantity that counts, but also quality. The process of dispersal can change disperser quality and establishment success. Invasions are a form of extra-range dispersal, so that invaders often experience changes in quality through dispersal. To study effects of dispersal on invader quality, and its interactions with quantity on invasion success, we manipulated both in a field experiment using an invasive marine invertebrate. Establishment success increased with the number of individuals arriving in a new habitat. Prolonged larval durations--our manipulation of prolonged dispersal--decreased individual quality and establishment success. Groups of invaders with prolonged larval durations contributed only a third of the offspring relative to invaders that settled immediately. We also found an interaction between the quality and quantity of invaders on individual growth: only within high-quality cohorts did individuals experience density-dependent effects on growth. Our findings highlight that dispersal not only affects the quantity of invaders arriving in a new habitat but also their quality, and both mediate establishment success. PMID:27197384

  7. Lectures on Dispersion Theory

    DOE R&D Accomplishments Database

    Salam, A.

    1956-04-01

    Lectures with mathematical analysis are given on Dispersion Theory and Causality and Dispersion Relations for Pion-nucleon Scattering. The appendix includes the S-matrix in terms of Heisenberg Operators. (F. S.)

  8. Ecological traits influencing range expansion across large oceanic dispersal barriers: insights from tropical Atlantic reef fishes.

    PubMed

    Luiz, Osmar J; Madin, Joshua S; Robertson, D Ross; Rocha, Luiz A; Wirtz, Peter; Floeter, Sergio R

    2012-03-01

    How do biogeographically different provinces arise in response to oceanic barriers to dispersal? Here, we analyse how traits related to the pelagic dispersal and adult biology of 985 tropical reef fish species correlate with their establishing populations on both sides of two Atlantic marine barriers: the Mid-Atlantic Barrier (MAB) and the Amazon-Orinoco Plume (AOP). Generalized linear mixed-effects models indicate that predictors for successful barrier crossing are the ability to raft with flotsam for the deep-water MAB, non-reef habitat usage for the freshwater and sediment-rich AOP, and large adult-size and large latitudinal-range for both barriers. Variation in larval-development mode, often thought to be broadly related to larval-dispersal potential, is not a significant predictor in either case. Many more species of greater taxonomic diversity cross the AOP than the MAB. Rafters readily cross both barriers but represent a much smaller proportion of AOP crossers than MAB crossers. Successful establishment after crossing both barriers may be facilitated by broad environmental tolerance associated with large body size and wide latitudinal-range. These results highlight the need to look beyond larval-dispersal potential and assess adult-biology traits when assessing determinants of successful movements across marine barriers. PMID:21920979

  9. Different key roles of mesoscale oceanographic structures and ocean bathymetry in shaping larval fish distribution pattern: A case study in Sicilian waters in summer 2009

    NASA Astrophysics Data System (ADS)

    Cuttitta, Angela; Quinci, Enza Maria; Patti, Bernardo; Bonomo, Sergio; Bonanno, Angelo; Musco, Marianna; Torri, Marco; Placenti, Francesco; Basilone, Gualtiero; Genovese, Simona; Armeri, Grazia Maria; Spanò, Antonina; Arculeo, Marco; Mazzola, Antonio; Mazzola, Salvatore

    2016-09-01

    Fish larvae data collected in year 2009 were used to examine the effects of particular environmental conditions on the structure of larval assemblages in two oligotrophic Mediterranean areas (the Southern Tyrrhenian Sea and the Strait of Sicily). For this purpose, relationships with environmental variables (temperature, salinity and fluorescence), zooplankton biomass, water circulation and bathymetry are discussed. Hydrodynamic conditions resulted very differently between two study areas. The Southern Tyrrhenian Sea was characterized by moderate shallow circulation compared to the Strait of Sicily. In this framework, distribution pattern of larval density in the Tyrrhenian Sea was mainly driven by bathymetry, due to spawning behavior of adult fish. There, results defined four assemblages: two coastal assemblages dominated by pelagic and demersal families and two oceanic assemblages dominated by mesopelagic species more abundant in western offshore and less abundant in eastern offshore. The assemblage variations in the western side was related to the presence of an anti-cyclonic gyre in the northern side of the Gulf of Palermo, while in the eastern side the effect of circulation was not very strong and the environmental conditions rather than the dispersal of species determined the larval fish communities structure. Otherwise in the Strait of Sicily the currents were the main factor governing the concentration and the assemblage structure. In fact, the distribution of larvae was largely consistent with the branch of the Atlantic Ionian Stream (AIS). Moreover, very complex oceanographic structures (two cyclonic circulations in the western part of the study area and one anti-cyclonic circulation in the eastern part) caused the formation of uncommon spatial distribution of larval fish assemblages, only partially linked to bathymetry of the study area. Typically coastal larvae (pelagic families: Engraulidae and Clupeidae) were mostly concentrated in the offshore areas

  10. Dispersion y dinamica poblacional

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dispersal behavior of fruit flies is appetitive. Measures of dispersion involve two different parameter: the maximum distance and the standard distance. Standard distance is a parameter that describes the probalility of dispersion and is mathematically equivalent to the standard deviation around ...

  11. Matching spatial property rights fisheries with scales of fish dispersal.

    PubMed

    White, Crow; Costello, Christopher

    2011-03-01

    Regulation of fisheries using spatial property rights can alleviate competition for high-value patches that hinders economic efficiency in quota-based, rights-based, and open-access management programs. However, efficiency gains erode when delineation of spatial rights constitutes incomplete ownership of the resource, thereby degrading its local value and promoting overexploitation. Incomplete ownership may be particularly prevalent in the spatial management of mobile fishery species. We developed a game-theoretic bioeconomic model of spatial property rights representing territorial user rights fisheries (TURF) management of nearshore marine fish and invertebrate species with mobile adult and larval life history stages. Strategic responses by fisheries in neighboring management units result in overexploitation of the stock and reduced yields for each fishery compared with those attainable without resource mobility or with coordination or sole control in fishing effort. High dispersal potential of the larval stage, a common trait among nearshore fishery species, coupled with scaling of management units to only capture adult mobility, a common characteristic of many nearshore TURF programs, in particular substantially reduced stock levels and yields. In a case study of hypothetical TURF programs of nearshore fish and invertebrate species, management units needed to be tens of kilometers in alongshore length to minimize larval export and generate reasonable returns to fisheries. Cooperation and quota regulations represent solutions to the problem that need to be quantified in cost and integrated into the determination of the acceptability of spatial property rights management of fisheries. PMID:21563568

  12. Theory of dispersive microlenses

    NASA Technical Reports Server (NTRS)

    Herman, B.; Gal, George

    1993-01-01

    A dispersive microlens is a miniature optical element which simultaneously focuses and disperses light. Arrays of dispersive mircolenses have potential applications in multicolor focal planes. They have a 100 percent optical fill factor and can focus light down to detectors of diffraction spot size, freeing up areas on the focal plane for on-chip analog signal processing. Use of dispersive microlenses allows inband color separation within a pixel and perfect scene registration. A dual-color separation has the potential for temperature discrimination. We discuss the design of dispersive microlenses and present sample results for efficient designs.

  13. The influence of substrate material on ascidian larval settlement.

    PubMed

    Chase, Anna L; Dijkstra, Jennifer A; Harris, Larry G

    2016-05-15

    Submerged man-made structures present novel habitat for marine organisms and often host communities that differ from those on natural substrates. Although many factors are known to contribute to these differences, few studies have directly examined the influence of substrate material on organism settlement. We quantified larval substrate preferences of two species of ascidians, Ciona intestinalis (cryptogenic, formerly C. intestinalis type B) and Botrylloides violaceus (non-native), on commonly occurring natural (granite) and man-made (concrete, high-density polyethylene, PVC) marine materials in laboratory trials. Larvae exhibited species-specific settlement preferences, but generally settled more often than expected by chance on concrete and HDPE. Variation in settlement between materials may reflect preferences for rougher substrates, or may result from the influence of leached chemicals on ascidian settlement. These findings indicate that an experimental plate material can influence larval behavior and may help us understand how substrate features may contribute to differences in settlement in the field. PMID:27039957

  14. Learning the specific quality of taste reinforcement in larval Drosophila

    PubMed Central

    Schleyer, Michael; Miura, Daisuke; Tanimura, Teiichi; Gerber, Bertram

    2015-01-01

    The only property of reinforcement insects are commonly thought to learn about is its value. We show that larval Drosophila not only remember the value of reinforcement (How much?), but also its quality (What?). This is demonstrated both within the appetitive domain by using sugar vs amino acid as different reward qualities, and within the aversive domain by using bitter vs high-concentration salt as different qualities of punishment. From the available literature, such nuanced memories for the quality of reinforcement are unexpected and pose a challenge to present models of how insect memory is organized. Given that animals as simple as larval Drosophila, endowed with but 10,000 neurons, operate with both reinforcement value and quality, we suggest that both are fundamental aspects of mnemonic processing—in any brain. DOI: http://dx.doi.org/10.7554/eLife.04711.001 PMID:25622533

  15. Cost effectiveness analysis of larval therapy for leg ulcers

    PubMed Central

    Iglesias, Cynthia P; Bland, J Martin; Cullum, Nicky; Dumville, Jo C; Nelson, E Andrea; Torgerson, David J; Worthy, Gill

    2009-01-01

    Objective To assess the cost effectiveness of larval therapy compared with hydrogel in the management of leg ulcers. Design Cost effectiveness and cost utility analyses carried out alongside a pragmatic multicentre, randomised, open trial with equal randomisation. Population Intention to treat population comprising 267 patients with a venous or mixed venous and arterial ulcers with at least 25% coverage of slough or necrotic tissue. Interventions Patients were randomly allocated to debridement with bagged larvae, loose larvae, or hydrogel. Main outcome measure The time horizon was 12 months and costs were estimated from the UK National Health Service perspective. Cost effectiveness outcomes are expressed in terms of incremental costs per ulcer-free day (cost effectiveness analysis) and incremental costs per quality adjusted life years (cost utility analysis). Results The larvae arms were pooled for the main analysis. Treatment with larval therapy cost, on average, £96.70 (€109.61; $140.57) more per participant per year (95% confidence interval −£491.9 to £685.8) than treatment with hydrogel. Participants treated with larval therapy healed, on average, 2.42 days before those in the hydrogel arm (95% confidence interval −0.95 to 31.91 days) and had a slightly better health related quality of life, as the annual difference in QALYs was 0.011 (95% confidence interval −0.067 to 0.071). However, none of these differences was statistically significant. The incremental cost effectiveness ratio for the base case analysis was estimated at £8826 per QALY gained and £40 per ulcer-free day. Considerable uncertainty surrounds the outcome estimates. Conclusions Debridement of sloughy or necrotic leg ulcers with larval therapy is likely to produce similar health benefits and have similar costs to treatment with hydrogel. Trial registration Current Controlled Trials ISRCTN55114812 and National Research Register N0484123692. PMID:19304578

  16. Social coercion of larval development in an ant species

    NASA Astrophysics Data System (ADS)

    Villalta, Irene; Amor, Fernando; Cerdá, Xim; Boulay, Raphaël

    2016-04-01

    Ants provide one of the best examples of the division of labor in animal societies. While the queens reproduce, workers generally refrain from laying eggs and dedicate themselves exclusively to domestic tasks. In many species, the small diploid larvae are bipotent and can develop either into workers or queens depending mostly on environmental cues. This generates a conflicting situation between the adults that tend to rear a majority of larvae into workers and the larvae whose individual interest may be to develop into reproductive queens. We tested the social regulation of larval caste fate in the fission-performing ant Aphaenogaster senilis. We first observed interactions between resident workers and queen- and worker-destined larvae in presence/absence of the queen. The results show that workers tend to specifically eliminate queen-destined larvae when the queen is present but not when she is absent or imprisoned in a small cage allowing for volatile pheromone exchanges. In addition, we found that the presence of already developed queen-destined larvae does not inhibit the development of younger still bipotent larvae into queens. Finally, we analyzed the cuticular hydrocarbon profiles of queen- and worker-destined larvae and found no significant quantitative or qualitative difference. Interestingly, the total amount of hydrocarbons on both larval castes is extremely low, which lends credence on the chemical insignificance hypothesis of larval ants. Overall, our results suggest that workers control larval development and police larvae that would develop into queens instead of workers. Such policing behavior is similar in many aspects to what is known of worker policing among adults.

  17. Social coercion of larval development in an ant species.

    PubMed

    Villalta, Irene; Amor, Fernando; Cerdá, Xim; Boulay, Raphaël

    2016-04-01

    Ants provide one of the best examples of the division of labor in animal societies. While the queens reproduce, workers generally refrain from laying eggs and dedicate themselves exclusively to domestic tasks. In many species, the small diploid larvae are bipotent and can develop either into workers or queens depending mostly on environmental cues. This generates a conflicting situation between the adults that tend to rear a majority of larvae into workers and the larvae whose individual interest may be to develop into reproductive queens. We tested the social regulation of larval caste fate in the fission-performing ant Aphaenogaster senilis. We first observed interactions between resident workers and queen- and worker-destined larvae in presence/absence of the queen. The results show that workers tend to specifically eliminate queen-destined larvae when the queen is present but not when she is absent or imprisoned in a small cage allowing for volatile pheromone exchanges. In addition, we found that the presence of already developed queen-destined larvae does not inhibit the development of younger still bipotent larvae into queens. Finally, we analyzed the cuticular hydrocarbon profiles of queen- and worker-destined larvae and found no significant quantitative or qualitative difference. Interestingly, the total amount of hydrocarbons on both larval castes is extremely low, which lends credence on the chemical insignificance hypothesis of larval ants. Overall, our results suggest that workers control larval development and police larvae that would develop into queens instead of workers. Such policing behavior is similar in many aspects to what is known of worker policing among adults. PMID:26874941

  18. Development of Drosophila larval neuromuscular junctions: maintaining synaptic strength.

    PubMed

    Li, H; Peng, X; Cooper, R L

    2002-01-01

    In spite of the available information about the development of Drosophila neuromuscular junctions, the correlation between nerve terminal morphology and maintenance of synaptic strength has still not been systematically addressed throughout larval development. We characterized the growth of the abdominal longitudinal muscle 6 (m6) and the motor terminals Ib and Is that innervate it within segment 4. In addition, we measured the evoked excitatory junction potential (EJP) amplitudes while the Ib and Is axons were selectively recruited. Regression analysis with natural log transformation of response variables indicated that the developmental curves for m6 and the motor axons Ib and Is were best fitted as second order polynomial regressions during larval development. Initially Is terminals are longer and possess more synaptic varicosities at the first instar stage. The Is terminals also grow faster in subsequent developmental stages. The growth of nerve terminals and their target m6 are not proportional although tightly correlated. This results in a larger average muscle area innervated by a single varicosity as the animal develops. The amplitudes of the EJPs of Ib and Is neurons show no developmental difference in their amplitudes from the first to the late third larval instar. The Is axon consistently produced larger EJPs than the Ib axon at each developmental stage. The time constants for both rising and decay phases of EJPs increase exponentially throughout larval development. The results presented not only help in quantifying the normal development of Drosophila neuromuscular junctions, but also provide a framework for future investigations to properly interpret developmental abnormalities that may occur in various mutants. PMID:12421617

  19. Larval RNA interference in the red flour beetle, Tribolium castaneum.

    PubMed

    Linz, David M; Clark-Hachtel, Courtney M; Borràs-Castells, Ferran; Tomoyasu, Yoshinori

    2014-01-01

    The red flour beetle, Tribolium castaneum, offers a repertoire of experimental tools for genetic and developmental studies, including a fully annotated genome sequence, transposon-based transgenesis, and effective RNA interference (RNAi). Among these advantages, RNAi-based gene knockdown techniques are at the core of Tribolium research. T. castaneum show a robust systemic RNAi response, making it possible to perform RNAi at any life stage by simply injecting double-stranded RNA (dsRNA) into the beetle's body cavity. In this report, we provide an overview of our larval RNAi technique in T. castaneum. The protocol includes (i) isolation of the proper stage of T. castaneum larvae for injection, (ii) preparation for the injection setting, and (iii) dsRNA injection. Larval RNAi is a simple, but powerful technique that provides us with quick access to loss-of-function phenotypes, including multiple gene knockdown phenotypes as well as a series of hypomorphic phenotypes. Since virtually all T. castaneum tissues are susceptible to extracellular dsRNA, the larval RNAi technique allows researchers to study a wide variety of tissues in diverse contexts, including the genetic basis of organismal responses to the outside environment. In addition, the simplicity of this technique stimulates more student involvement in research, making T. castaneum an ideal genetic system for use in a classroom setting. PMID:25350485

  20. Evaluation of Human Attachment by Larval Amblyomma maculatum (Acari: Ixodidae).

    PubMed

    Portugal, José Santos; Goddard, Jerome

    2016-03-01

    The tick, Amblyomma maculatum Koch (Gulf Coast tick), has recently been shown to be an important disease vector of both medical and veterinary concern. Although much is known about the behavior and ecology of adults, little is known of the immatures. Larval feeding on humans has never been demonstrated (and thus, there are no collection records from humans). In this experiment, 10 larval A. maculatum, Amblyomma americanum (L.) (a positive control), and Dermacentor variabilis (Say) (a negative control), were applied to both forearms of 10 human volunteers (five male, five female). Ticks were placed in plastic caps and secured to skin with medical-grade adhesive tape, and volunteers remained sedentary during the experiment. After 15 min, caps were removed, and attachment was determined using fine-tipped forceps. Any A. maculatum that were attached were then removed and subsequently examined microscopically to verify identification. In total, 34 ticks attached to the subjects, including 11 A. maculatum (5.5%), 23 A. americanum (11.5%), and no D. variabilis. Amblyomma maculatum attached to six volunteers, and no apparent association between gender and attachment rate was noted. No skin lesions developed in the human volunteers bit by A. maculatum. This is the first report of larval A. maculatum attaching to humans, and is significant in that Rickettsia parkeri, a human pathogen vectored by this species, has recently been reported to be transmitted transovarially. If A. maculatum are infected as larvae, they could potentially transmit R. parkeri to people. PMID:26576936

  1. Larval RNA Interference in the Red Flour Beetle, Tribolium castaneum

    PubMed Central

    Tomoyasu, Yoshinori

    2014-01-01

    The red flour beetle, Tribolium castaneum, offers a repertoire of experimental tools for genetic and developmental studies, including a fully annotated genome sequence, transposon-based transgenesis, and effective RNA interference (RNAi). Among these advantages, RNAi-based gene knockdown techniques are at the core of Tribolium research. T. castaneum show a robust systemic RNAi response, making it possible to perform RNAi at any life stage by simply injecting double-stranded RNA (dsRNA) into the beetle’s body cavity. In this report, we provide an overview of our larval RNAi technique in T. castaneum. The protocol includes (i) isolation of the proper stage of T. castaneum larvae for injection, (ii) preparation for the injection setting, and (iii) dsRNA injection. Larval RNAi is a simple, but powerful technique that provides us with quick access to loss-of-function phenotypes, including multiple gene knockdown phenotypes as well as a series of hypomorphic phenotypes. Since virtually all T. castaneum tissues are susceptible to extracellular dsRNA, the larval RNAi technique allows researchers to study a wide variety of tissues in diverse contexts, including the genetic basis of organismal responses to the outside environment. In addition, the simplicity of this technique stimulates more student involvement in research, making T. castaneum an ideal genetic system for use in a classroom setting. PMID:25350485

  2. Assessment of current rates of Diadema antillarum larval settlement

    NASA Astrophysics Data System (ADS)

    Miller, M. W.; Kramer, K. L.; Williams, S. M.; Johnston, L.; Szmant, A. M.

    2009-06-01

    The generally slow and incomplete recovery of the long-spined sea urchin, Diadema antillarum, from the 1983-84 Caribbean-wide die-off, particularly in the Florida Keys, USA, raises the question of factors limiting population recovery. This study sought to quantify larval settlement rates as an indicator of larval supply at two sites in the Florida Keys, utilizing methods comparable to an historic study. Settlement at two sites in southwest Puerto Rico was also examined as a comparison of present-day settlement rates at a site where D. antillarum recovery has been moderate. Monthly settlement rates were low (max < 2 m-2) and did not differ between the two sites examined in the Florida Keys. Settlement was significantly higher at only one of the Puerto Rico sites (max 16 m-2), but still an order of magnitude lower than that reported for historic populations in Curaçao (1982-83). Results are consistent with the hypothesis of low larval supply limiting D. antillarum recovery in the Florida Keys.

  3. Larval Defense against Attack from Parasitoid Wasps Requires Nociceptive Neurons

    PubMed Central

    Robertson, Jessica L.; Tsubouchi, Asako; Tracey, W. Daniel

    2013-01-01

    Parasitoid wasps are a fierce predator of Drosophila larvae. Female Leptopilina boulardi (LB) wasps use a sharp ovipositor to inject eggs into the bodies of Drosophila melanogaster larvae. The wasp then eats the Drosophila larva alive from the inside, and an adult wasp ecloses from the Drosophila pupal case instead of a fly. However, the Drosophila larvae are not defenseless as they may resist the attack of the wasps through somatosensory-triggered behavioral responses. Here we describe the full range of behaviors performed by the larval prey in immediate response to attacks by the wasps. Our results suggest that Drosophila larvae primarily sense the wasps using their mechanosensory systems. The range of behavioral responses included both “gentle touch” like responses as well as nociceptive responses. We found that the precise larval response depended on both the somatotopic location of the attack, and whether or not the larval cuticle was successfully penetrated during the course of the attack. Interestingly, nociceptive responses are more likely to be triggered by attacks in which the cuticle had been successfully penetrated by the wasp. Finally, we found that the class IV neurons, which are necessary for mechanical nociception, were also necessary for a nociceptive response to wasp attacks. Thus, the class IV neurons allow for a nociceptive behavioral response to a naturally occurring predator of Drosophila. PMID:24205297

  4. Characterisation of Culex quinquefasciatus (Diptera: Culicidae) larval habitats at ground level and temporal fluctuations of larval abundance in Córdoba, Argentina.

    PubMed

    Grech, Marta; Sartor, Paolo; Estallo, Elizabet; Ludueña-Almeida, Francisco; Almirón, Walter

    2013-09-01

    The aims of this study were to characterise the ground-level larval habitats of the mosquito Culex quinquefasciatus, to determine the relationships between habitat characteristics and larval abundance and to examine seasonal larval-stage variations in Córdoba city. Every two weeks for two years, 15 larval habitats (natural and artificial water bodies, including shallow wells, drains, retention ponds, canals and ditches) were visited and sampled for larval mosquitoes. Data regarding the water depth, temperature and pH, permanence, the presence of aquatic vegetation and the density of collected mosquito larvae were recorded. Data on the average air temperatures and accumulated precipitation during the 15 days prior to each sampling date were also obtained. Cx. quinquefasciatus larvae were collected throughout the study period and were generally most abundant in the summer season. Generalised linear mixed models indicated the average air temperature and presence of dicotyledonous aquatic vegetation as variables that served as important predictors of larval densities. Additionally, permanent breeding sites supported high larval densities. In Córdoba city and possibly in other highly populated cities at the same latitude with the same environmental conditions, control programs should focus on permanent larval habitats with aquatic vegetation during the early spring, when the Cx. quinquefasciatus population begins to increase. PMID:24037200

  5. Characterisation of Culex quinquefasciatus (Diptera: Culicidae) larval habitats at ground level and temporal fluctuations of larval abundance in Córdoba, Argentina

    PubMed Central

    Grech, Marta; Sartor, Paolo; Estallo, Elizabet; Ludueña-Almeida, Francisco; Almirón, Walter

    2013-01-01

    The aims of this study were to characterise the ground-level larval habitats of the mosquito Culex quinquefasciatus, to determine the relationships between habitat characteristics and larval abundance and to examine seasonal larval-stage variations in Córdoba city. Every two weeks for two years, 15 larval habitats (natural and artificial water bodies, including shallow wells, drains, retention ponds, canals and ditches) were visited and sampled for larval mosquitoes. Data regarding the water depth, temperature and pH, permanence, the presence of aquatic vegetation and the density of collected mosquito larvae were recorded. Data on the average air temperatures and accumulated precipitation during the 15 days prior to each sampling date were also obtained. Cx. quinquefasciatus larvae were collected throughout the study period and were generally most abundant in the summer season. Generalised linear mixed models indicated the average air temperature and presence of dicotyledonous aquatic vegetation as variables that served as important predictors of larval densities. Additionally, permanent breeding sites supported high larval densities. In Córdoba city and possibly in other highly populated cities at the same latitude with the same environmental conditions, control programs should focus on permanent larval habitats with aquatic vegetation during the early spring, when the Cx. quinquefasciatus population begins to increase. PMID:24037200

  6. Serologically defined Rhipicephalus (Boophilus) microplus larval antigens in BmLF3, a partially pure Sephacryl S-300 fraction of crude larval proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This report is the second in a series providing a database of Rhipicephalus (Boophilus) microplus larval proteins that elicit a humoral immune response in cattle as a result of natural ectoparasite infestation. Larval proteins of R. microplus are complex and the profile is not dominated by any majo...

  7. Device Connectivity

    PubMed Central

    Walsh, John; Roberts, Ruth; Morris, Richard

    2015-01-01

    Patients with diabetes have to take numerous factors/data into their therapeutic decisions in daily life. Connecting the devices they are using by feeding the data generated into a database/app is supposed to help patients to optimize their glycemic control. As this is not established in practice, the different roadblocks have to be discussed to open the road. That large telecommunication companies are now entering this market might be a big help in pushing this forward. Smartphones offer an ideal platform for connectivity solutions. PMID:25614015

  8. Evolution of poecilogony from planktotrophy: cryptic speciation, phylogeography, and larval development in the gastropod genus Alderia.

    PubMed

    Ellingson, Ryan A; Krug, Patrick J

    2006-11-01

    Poecilogony, a rare phenomenon in marine invertebrates, occurs when alternative larval morphs differing in dispersal potential or trophic mode are produced from a single genome. Because both poecilogony and cryptic species are prevalent among sea slugs in the suborder Sacoglossa (Gastropoda: Opisthobranchia), molecular data are needed to confirm cases of variable development and to place them in a phylogenetic context. The nominal species Alderia modesta produces long-lived, feeding larvae throughout the North Atlantic and Pacific, but in California can also produce short-lived larvae that metamorphose without feeding. We collected morphological, developmental, and molecular data for Alderia from 17 sites spanning the eastern and western Pacific and North Atlantic. Estuaries south of Bodega Harbor, California, contained a cryptic species (hereafter Alderia sp.) with variable development, sister to the strictly planktotrophic A. modesta. The smaller Alderia sp. seasonally toggled between planktotrophy and lecithotrophy, with some individuals differing in development but sharing mitochondrial DNA haplotypes. The sibling species overlapped in Tomales Bay, California, but showed no evidence of hybridization; laboratory mating trials suggest postzygotic isolation has arisen. Intra- and interspecific divergence times were estimated using a molecular clock calibrated with geminate sacoglossans. Speciation occurred about 4.1 million years ago during a major marine radiation in the eastern Pacific, when large inland embayments in California may have isolated ancestral populations. Atlantic and Pacific A. modesta diverged about 1.7 million years ago, suggesting trans-Arctic gene flow was interrupted by Pleistocene glaciation. Both Alderia species showed evidence of late Pleistocene population expansion, but the southern Alderia sp. likely experienced a more pronounced bottleneck. Reduced body size may have incurred selection against obligate planktotrophy in Alderia sp. by

  9. Evolution of increased adult longevity in Drosophila melanogaster populations selected for adaptation to larval crowding.

    PubMed

    Shenoi, V N; Ali, S Z; Prasad, N G

    2016-02-01

    In holometabolous animals such as Drosophila melanogaster, larval crowding can affect a wide range of larval and adult traits. Adults emerging from high larval density cultures have smaller body size and increased mean life span compared to flies emerging from low larval density cultures. Therefore, adaptation to larval crowding could potentially affect adult longevity as a correlated response. We addressed this issue by studying a set of large, outbred populations of D. melanogaster, experimentally evolved for adaptation to larval crowding for 83 generations. We assayed longevity of adult flies from both selected (MCUs) and control populations (MBs) after growing them at different larval densities. We found that MCUs have evolved increased mean longevity compared to MBs at all larval densities. The interaction between selection regime and larval density was not significant, indicating that the density dependence of mean longevity had not evolved in the MCU populations. The increase in longevity in MCUs can be partially attributed to their lower rates of ageing. It is also noteworthy that reaction norm of dry body weight, a trait probably under direct selection in our populations, has indeed evolved in MCU populations. To the best of our knowledge, this is the first report of the evolution of adult longevity as a correlated response of adaptation to larval crowding. PMID:26575793

  10. Dispersal kernel estimation: A comparison of empirical and modelled particle dispersion in a coastal marine system

    NASA Astrophysics Data System (ADS)

    Hrycik, Janelle M.; Chassé, Joël; Ruddick, Barry R.; Taggart, Christopher T.

    2013-11-01

    Early life-stage dispersal influences recruitment and is of significance in explaining the distribution and connectivity of marine species. Motivations for quantifying dispersal range from biodiversity conservation to the design of marine reserves and the mitigation of species invasions. Here we compare estimates of real particle dispersion in a coastal marine environment with similar estimates provided by hydrodynamic modelling. We do so by using a system of magnetically attractive particles (MAPs) and a magnetic-collector array that provides measures of Lagrangian dispersion based on the time-integration of MAPs dispersing through the array. MAPs released as a point source in a coastal marine location dispersed through the collector array over a 5-7 d period. A virtual release and observed (real-time) environmental conditions were used in a high-resolution three-dimensional hydrodynamic model to estimate the dispersal of virtual particles (VPs). The number of MAPs captured throughout the collector array and the number of VPs that passed through each corresponding model location were enumerated and compared. Although VP dispersal reflected several aspects of the observed MAP dispersal, the comparisons demonstrated model sensitivity to the small-scale (random-walk) particle diffusivity parameter (Kp). The one-dimensional dispersal kernel for the MAPs had an e-folding scale estimate in the range of 5.19-11.44 km, while those from the model simulations were comparable at 1.89-6.52 km, and also demonstrated sensitivity to Kp. Variations among comparisons are related to the value of Kp used in modelling and are postulated to be related to MAP losses from the water column and (or) shear dispersion acting on the MAPs; a process that is constrained in the model. Our demonstration indicates a promising new way of 1) quantitatively and empirically estimating the dispersal kernel in aquatic systems, and 2) quantitatively assessing and (or) improving regional hydrodynamic

  11. Impact of dispersal on the stability of metapopulations.

    PubMed

    Tromeur, Eric; Rudolf, Lars; Gross, Thilo

    2016-03-01

    Dispersal is a key ecological process that enables local populations to form spatially extended systems called metapopulations. In the present study, we investigate how dispersal affects the linear stability of a general single-species metapopulation model. We discuss both the influence of local within-patch dynamics and the effects of various dispersal behaviours on stability. We find that positive density-dependent dispersal and positive density-dependent settlement are destabilizing dispersal behaviours while negative density-dependent dispersal and negative density-dependent settlement are stabilizing. It is also shown that dispersal has a stabilizing impact on heterogeneous metapopulations that correlates positively with the number of patches and the connectance of metapopulation networks. PMID:26723533

  12. Larval and Post-Larval Stages of Pacific Oyster (Crassostrea gigas) Are Resistant to Elevated CO2

    PubMed Central

    R, Dineshram; Dennis, Choi K. S.; Adela, Li J.; Yu, Ziniu; Thiyagarajan, Vengatesen

    2013-01-01

    The average pH of surface oceans has decreased by 0.1 unit since industrialization and is expected to decrease by another 0.3–0.7 units before the year 2300 due to the absorption of anthropogenic CO2. This human-caused pH change is posing serious threats and challenges to the Pacific oyster (Crassostrea gigas), especially to their larval stages. Our knowledge of the effect of reduced pH on C. gigas larvae presently relies presumptively on four short-term (<4 days) survival and growth studies. Using multiple physiological measurements and life stages, the effects of long-term (40 days) exposure to pH 8.1, 7.7 and 7.4 on larval shell growth, metamorphosis, respiration and filtration rates at the time of metamorphosis, along with the juvenile shell growth and structure of the C. gigas, were examined in this study. The mean survival and growth rates were not affected by pH. The metabolic, feeding and metamorphosis rates of pediveliger larvae were similar, between pH 8.1 and 7.7. The pediveligers at pH 7.4 showed reduced weight-specific metabolic and filtration rates, yet were able to sustain a more rapid post-settlement growth rate. However, no evidence suggested that low pH treatments resulted in alterations to the shell ultrastructures (SEM images) or elemental compositions (i.e., Mg/Ca and Sr/Ca ratios). Thus, larval and post-larval forms of the C. gigas in the Yellow Sea are probably resistant to elevated CO2 and decreased near-future pH scenarios. The pre-adapted ability to resist a wide range of decreased pH may provide C. gigas with the necessary tolerance to withstand rapid pH changes over the coming century. PMID:23724027

  13. Connecting Node

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J.; Raboin, Jasen L.; Spexarth, Gary R.

    2009-01-01

    A paper describes the Octanode, a connecting node that facilitates the integration of multiple docking mechanisms, hatches, windows, and internal and external systems with the use of flat surfaces. The Octanode is a 26- faced Great Rhombicuboctahedron Archi medean solid with six octagonshaped panels, eight hexagon-shaped panels, and 12 square panels using three unique, simple, flat shapes to construct a spherical approximation. Each flat shape can be constructed with a variety of material and manufacturing techniques, such as honeycomb composite panels or a pocketed skinstringer configuration, using conventional means. The flat shapes can be connected together and sealed to create a pressurizable volume by the use of any conventional means including welding or fastening devices and sealant. The node can then be connected to other elements to allow transfer between those elements, or it could serve as an airlock. The Octanode can be manufactured on the ground and can be integrated with subsystems including hatches and ports. The node can then be transported to its intended location, whether on orbit or on surface. Any of the flat panels could be replaced by curved ones, turning the node into a copula. Windows may be placed on flat panes with optimal viewing angles that are not blocked by large connecting nodes. The advantage of using flat panels to represent a spherical approximation is that this allows for easier integration of subsystems and design features.

  14. Get Connected

    ERIC Educational Resources Information Center

    Horton, Jessica; Hagevik, Rita; Adkinson, Bennett; Parmly, Jilynn

    2013-01-01

    Technology can be both a blessing and a curse in the classroom. Although technology can provide greater access to information and increase student engagement, if screen time replaces time spent outside, then students stand to lose awareness and connectivity to the surrounding natural environment. This article describes how Google Earth can foster…

  15. Making Connections

    ERIC Educational Resources Information Center

    Quillen, Ian

    2014-01-01

    "We used to send out books that looked like this," says Barbara Dreyer, as she holds the 500-page volume from one of the first-ever courses offered online by Connections Academy. "You could look at this information online, but, frankly, a lot of people were doing this," she adds, thumbing through the book's pages. Dreyer,…

  16. Learning Connections

    ERIC Educational Resources Information Center

    Royer, Regina D.; Richards, Patricia O.

    2005-01-01

    In this edition of Learning Connections, the authors show how technology can enhance study of weather patterns, reading comprehension, real-world training, critical thinking, health education, and art criticism. The following sections are included: (1) Social Studies; (2) Language Arts; (3) Computer Science and ICT; (4) Art; and (5) Health.…

  17. College Connection

    ERIC Educational Resources Information Center

    Hewitt, Kimberly Kappler; Scalzo, Mary Jo

    2012-01-01

    This article describes Oakwood City School District's College Connection Study, which is now in its eighth year. The purpose of the study is to help the educators in the district learn how to effectively prepare students for success in the colleges of their choice. Teachers, administrators, and other staff members travel to colleges to conduct…

  18. Effects of Salinity on Oil Spill Dispersant Toxicity in Estuarine Organisms

    NASA Astrophysics Data System (ADS)

    Eckmann, C. A.

    2015-12-01

    Chemical dispersants can be a useful tool to mitigate oil spills, but the potential risks to sensitive estuarine species should be carefully considered. To improve the decision making process, more information is needed regarding the effects of oil spill dispersants on the health of coastal ecosystems under variable environmental conditions such as salinity. The two oil dispersants used in this study were Corexit ® 9500 and Finasol ® OSR 52. Corexit ® 9500 was the primary dispersant used during the 2010 Deepwater Horizon oil spill event, while Finasol® OSR 52 is another dispersant approved for oil spill response in the U.S., yet considerably less is known regarding its toxicity to estuarine species. The grass shrimp, Palaemonetes pugio, was used as a model estuarine species. It is a euryhaline species that tolerates salinities from brackish to full strength seawater. Adult and larval life stages were tested with each dispersant at three salinities, 5ppt, 20ppt, and 30ppt. Median acute lethal toxicity thresholds were calculated. Lipid peroxidation assays were conducted on surviving shrimp to investigate sublethal effects. The toxicity of both dispersants was significantly influenced by salinity, with greatest toxicity observed at the lowest salinity tested. Larval shrimp were significantly more sensitive than adult shrimp to both dispersants, and both life stages were significantly more sensitive to Finasol than to Corexit. Furthermore, significant sublethal effects were seen at higher concentrations of both dispersants compared to the control. These data will enable environmental managers to make informed decisions regarding dispersant use in future oil spills.

  19. Dispersant Corexit 9500A and chemically dispersed crude oil decreases the growth rates of meroplanktonic barnacle nauplii (Amphibalanus improvisus) and tornaria larvae (Schizocardium sp.).

    PubMed

    Almeda, Rodrigo; Bona, Shawn; Foster, Charles R; Buskey, Edward J

    2014-08-01

    Our knowledge of the lethal and sublethal effects of dispersants and dispersed crude oil on meroplanktonic larvae is limited despite the importance of planktonic larval stages in the life cycle of benthic invertebrates. We determined the effects of Light Louisiana Sweet crude oil, dispersant Corexit 9500A, and dispersant-treated crude oil on the survival and growth rates of nauplii of the barnacle Amphibalanus improvisus and tornaria larvae of the enteropneust Schizocardium sp. Growth rates of barnacle nauplii and tornaria larvae were significantly reduced after exposure to chemically dispersed crude oil and dispersant Corexit 9500A at concentrations commonly found in the water column after dispersant application in crude oil spills. We also found that barnacle nauplii ingested dispersed crude oil, which may have important consequences for the biotransfer of petroleum hydrocarbons through coastal pelagic food webs after a crude oil spill. Therefore, application of chemical dispersants increases the impact of crude oil spills on meroplanktonic larvae, which may affect recruitment and population dynamics of marine benthic invertebrates. PMID:25028258

  20. Ant benefits in a seed dispersal mutualism.

    PubMed

    Gammans, Nicola; Bullock, James M; Schönrogge, Karsten

    2005-11-01

    Myrmecochorous plant seeds have nutrient rich appendages, elaiosomes, which induce some ant species to carry the seeds back to their nest where the elaiosome is consumed and the seed is discarded unharmed. The benefits to plants of dispersal of their seeds in this way have been well documented, but the benefits to the ants from consuming the elaiosomes have rarely been measured and are less clear. Ant benefits from myrmecochory were investigated in a laboratory experiment using the ant Myrmica ruginodis and seeds of Ulex species. To separate the effects of elaiosome consumption on the development of newly produced larvae versus existing larvae, ten 'Queenright' colonies containing a queen were compared to ten 'Queenless' colonies. Six measures of colony fitness over a complete annual cycle were taken: sexual production, larval weight and number, pupal weight and number, and worker survival. Queenless colonies fed with elaiosomes produced 100.0+/-29.3 (mean +/- SE) of larvae compared to non-elaiosome fed colonies which produced 49.6+/-19.0; an increase of 102%. Larval weight increased in both Queenright and Queenless colonies. In colonies fed with elaiosomes, larvae weighed 1.02+/-0.1 mg, but in non-elaiosome fed colonies larvae weighed 0.69+/-0.1 mg; an increase of 48%. The food supplement provided by Ulex elaiosomes was trivial in energetic terms, under the conditions of an ample diet, suggesting that these effects might be due to the presence of essential nutrients. Chemical analysis of Ulex elaiosomes showed the presence of four essential fatty acids and four essential sterols for ants. PMID:16049717

  1. Patterns of growth and tract formation during the early development of secondary lineages in the Drosophila larval brain.

    PubMed

    Lovick, Jennifer K; Kong, Angel; Omoto, Jaison J; Ngo, Kathy T; Younossi-Hartenstein, Amelia; Hartenstein, Volker

    2016-04-01

    The Drosophila brain consists of a relatively small number of invariant, genetically determined lineages which provide a model to study the relationship between gene function and neuronal architecture. In following this long-term goal, we reconstruct the morphology (projection pattern and connectivity) and gene expression patterns of brain lineages throughout development. In this article, we focus on the secondary phase of lineage morphogenesis, from the reactivation of neuroblast proliferation in the first larval instar to the time when proliferation ends and secondary axon tracts have fully extended in the late third larval instar. We have reconstructed the location and projection of secondary lineages at close (4 h) intervals and produced a detailed map in the form of confocal z-projections and digital three-dimensional models of all lineages at successive larval stages. Based on these reconstructions, we could compare the spatio-temporal pattern of axon formation and morphogenetic movements of different lineages in normal brain development. In addition to wild type, we reconstructed lineage morphology in two mutant conditions. (1) Expressing the construct UAS-p35 which rescues programmed cell death we could systematically determine which lineages normally lose hemilineages to apoptosis. (2) so-Gal4-driven expression of dominant-negative EGFR ablated the optic lobe, which allowed us to conclude that the global centrifugal movement normally affecting the cell bodies of lateral lineages in the late larva is causally related to the expansion of the optic lobe, and that the central pattern of axonal projections of these lineages is independent of the presence or absence of the optic lobe. PMID:26178322

  2. Expression and light-triggered movement of rhodopsins in the larval visual system of mosquitoes

    PubMed Central

    Rocha, Manuel; Kimler, Kyle J.; Leming, Matthew T.; Hu, Xiaobang; Whaley, Michelle A.; O'Tousa, Joseph E.

    2015-01-01

    ABSTRACT During the larval stages, the visual system of the mosquito Aedes aegypti contains five stemmata, often referred to as larval ocelli, positioned laterally on each side of the larval head. Here we show that stemmata contain two photoreceptor types, distinguished by the expression of different rhodopsins. The rhodopsin Aaop3 (GPROP3) is expressed in the majority of the larval photoreceptors. There are two small clusters of photoreceptors located within the satellite and central stemmata that express the rhodopsin Aaop7 (GPROP7) instead of Aaop3. Electroretinogram analysis of transgenic Aaop7 Drosophila indicates that Aaop3 and Aaop7, both classified as long-wavelength rhodopsins, possess similar but not identical spectral properties. Light triggers an extensive translocation of Aaop3 from the photosensitive rhabdoms to the cytoplasmic compartment, whereas light-driven translocation of Aaop7 is limited. The results suggest that these photoreceptor cell types play distinct roles in larval vision. An additional component of the larval visual system is the adult compound eye, which starts to develop at the anterior face of the larval stemmata during the 1st instar stage. The photoreceptors of the developing compound eye show rhodopsin expression during the 4th larval instar stage, consistent with indications from previous reports that the adult compound eye contributes to larval and pupal visual capabilities. PMID:25750414

  3. Butterfly oviposition preference is not related to larval performance on a polyploid herb.

    PubMed

    König, Malin A E; Wiklund, Christer; Ehrlén, Johan

    2016-05-01

    The preference-performance hypothesis predicts that female insects maximize their fitness by utilizing host plants which are associated with high larval performance. Still, studies with several insect species have failed to find a positive correlation between oviposition preference and larval performance. In the present study, we experimentally investigated the relationship between oviposition preferences and larval performance in the butterfly Anthocharis cardamines. Preferences were assessed using both cage experiments and field data on the proportion of host plant individuals utilized in natural populations. Larval performance was experimentally investigated using larvae descending from 419 oviposition events by 21 females on plants from 51 populations of two ploidy types of the perennial herb Cardamine pratensis. Neither ploidy type nor population identity influenced egg survival or larval development, but increased plant inflorescence size resulted in a larger final larval size. There was no correlation between female oviposition preference and egg survival or larval development under controlled conditions. Moreover, variation in larval performance among populations under controlled conditions was not correlated with the proportion of host plants utilized in the field. Lastly, first instar larvae added to plants rejected for oviposition by butterfly females during the preference experiment performed equally well as larvae growing on plants chosen for oviposition. The lack of a correlation between larval performance and oviposition preference for A. cardamines under both experimental and natural settings suggests that female host choice does not maximize the fitness of the individual offspring. PMID:27217940

  4. Cardiorespiratory ontogeny and response to environmental hypoxia of larval spiny lobster, Sagmariasus verreauxi.

    PubMed

    Fitzgibbon, Quinn P; Ruff, Nicole; Battaglene, Stephen C

    2015-06-01

    Cardiorespiratory function is vital to an organism's ability to respond to environmental stress and analysis of cardiorespiratory capacity of species or life stages can elucidate vulnerability to climate change. Spiny lobsters have one of the most complex pelagic larval life cycles of any invertebrate and recently there has been an unexplained decline in post-larval recruitment for a number of species. We conducted the first analysis of the larval ontogeny of oxygen consumption, heart rate, maxilla 2 ventilation rate and oxyregulatory capacity of the spiny lobster, Sagmariasus verreauxi, to gain insight into their vulnerability to ocean change and to investigate life stage specific sensitivity to temperature-dependent oxygen limitation. In normoxia, heart and maxilla 2 ventilation rates increased in early larval development before declining, which we hypothesise is related to the transition from myogenic to neurogenic cardiac control. Maxilla 2 ventilation rate was sensitive to hypoxia at all larval stages, while heart rate was only sensitive to hypoxia in the late phyllosoma stages. Oxygen consumption conformed to environmental hypoxia at all larval stages. Spiny lobster larvae have limited respiratory control due to immature gas exchange physiology, compounded by their exceptionally large size. The lack of oxyregulatory ability suggests that all development stages are vulnerable to changes in sea temperature and oxygen availability. The synergetic stressors of increased temperature and reduced dissolved oxygen in the marine environment will diminish spiny lobster larval performance, increasing the challenge to achieve their extended larval life cycle, which may contribute to declines in post-larval recruitment. PMID:25683612

  5. Redescription of the early larval stages of the pandalid shrimp Chlorotocus crassicornis (Decapoda: Caridea: Pandalidae).

    PubMed

    Landeira, Jose M; Jiang, Guo-Chen; Chan, Tin-Yam; Shih, Tung-Wei; Gozález-Gordillo, J Ignacio

    2015-01-01

    The first four larval stages of the pandalid shrimp Chlorotocus crassicornis (A. Costa, 1871) are described and illustrated from laboratory-reared material obtained from ovigerous females collected in the southwestern Spain and south Taiwan. The second to fourth larval stages of this species are reported for the first time to science. Detailed examination of the first larval stages reveals that previous description misidentified some key larval characters which have prevented its identification in plankton samples. It is found that the zoeal morphology of Chlorotocus is not very different from other pandalid larvae, and in fact closely resembles Plesionika and Heterocarpus. PMID:26623885

  6. Quantifying the drivers of larval density patterns in two tropical mosquito species to maximize control efficiency.

    PubMed

    De Little, Siobhan C; Bowman, David M J S; Whelan, Peter I; Brook, Barry W; Bradshaw, Corey J A

    2009-08-01

    Understanding the contributions of environmental variation and density feedbacks to changes in vector populations is essential for designing effective vector control. We analyzed monitoring datasets describing larval densities over 7 yr of the two dominant mosquito species, Aedes vigilax (Skuse) and Culex annulirostris (Skuse), of the greater Darwin area (Northern Territory, Australia). Using generalized linear and linear mixed-effects models, we tested hypotheses regarding the environmental determinants of spatio-temporal patterns in relative larval abundance in both species. The most important spatial drivers of Ae. vigilax and Cx. annulirostris larval densities were elevation and water presence. Ae. vigilax density correlates negatively with elevation, whereas there was a positive relationship between Cx. annulirostris density and elevation. These results show how larval habitats used by the saltwater-influenced breeder Ae. vigilax and the obligate freshwater breeder Cx. annulirostris are separated in a tidally influenced swamp. The models examining temporal drivers of larval density also identified this discrimination between freshwater and saltwater habitats. Ae. vigilax larval densities were positively related to maximum tide height and high tide frequency, whereas Cx. annulirostris larval densities were positively related to elevation and rainfall. Adult abundance in the previous month was the most important temporal driver of larval densities in both species, providing a clear dynamical link between the two main life phases in mosquito development. This study shows the importance of considering both spatial and temporal drivers, and intrinsic population dynamics, when planning vector control strategies to reduce larval density, adult population density, and disease transmission effectively. PMID:19689879

  7. Larval microhabitats of Lutzomyia longipalpis (Diptera: Psychodidae) in an endemic focus of visceral leishmaniasis in Colombia.

    PubMed

    Ferro, C; Pardo, R; Torres, M; Morrison, A C

    1997-11-01

    An intensive search for the larval habitats of Lutzomyia longipalpis (Lutz & Neiva) was conducted from November 1992 to October 1993 at a small rural community in Colombia where American visceral leishmaniasis is endemic. Emergence traps constructed from polyvinyl chloride pipes were used to sample a variety of soil microhabitats that included edge areas of covered pigpens, cattle corrals, the base of trees, and leaf litter at sites within 40 m of a house, rocks in fields located between 50 and 500 m from houses, and sites within a patch of secondary forest (rocks, base of palm trees, and leaf litter). The teneral status of the sand flies captured in the emergence traps was confirmed by laboratory studies that determined the rate of terminalia rotation in male L. longipalpis and the rate of cuticular growth layer formation of the thoracic phragma in both sexes of this species. A total of 58 teneral sand flies was captured during the study period (49 wk). Fifteen specimens were L. longipalpis; of these 11 (5 sand flies per square meter) were captured near pigpens, 3 (1.4 sand flies per square meter) were captured near rock resting sites, and 1 (1.6 sand flies per square meter) was collected at the base of a tree. The remainder of the sand flies were either L. trinidadensis (Newstead) or L. cayennensis (Flock & Abonnenc). Our results indicate that L. longipalpis larvae were dispersed widely in sites near houses, rather than concentrated in a few optimal microhabitats. PMID:9439128

  8. Visualizing Dispersion Interactions

    ERIC Educational Resources Information Center

    Gottschalk, Elinor; Venkataraman, Bhawani

    2014-01-01

    An animation and accompanying activity has been developed to help students visualize how dispersion interactions arise. The animation uses the gecko's ability to walk on vertical surfaces to illustrate how dispersion interactions play a role in macroscale outcomes. Assessment of student learning reveals that students were able to develop…

  9. Spores Disperse, Too!

    ERIC Educational Resources Information Center

    Schumann, Donna N.

    1981-01-01

    Suggests the use of spores and spore-producing structures to show adaptations facilitating spore dispersal and dispersal to favorable environments. Describes several activities using horsetails, ferns, and mosses. Lists five safety factors related to use of mold spores in the classroom. (DS)

  10. Dispersion strengthened copper

    DOEpatents

    Sheinberg, H.; Meek, T.T.; Blake, R.D.

    1990-01-09

    A composition of matter is described which is comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide. A method for making this composition of matter is also described. This invention relates to the art of powder metallurgy and, more particularly, it relates to dispersion strengthened metals.

  11. Dispersal of forest insects

    NASA Technical Reports Server (NTRS)

    Mcmanus, M. L.

    1979-01-01

    Dispersal flights of selected species of forest insects which are associated with periodic outbreaks of pests that occur over large contiguous forested areas are discussed. Gypsy moths, spruce budworms, and forest tent caterpillars were studied for their massive migrations in forested areas. Results indicate that large dispersals into forested areas are due to the females, except in the case of the gypsy moth.

  12. A Column Dispersion Experiment.

    ERIC Educational Resources Information Center

    Corapcioglu, M. Y.; Koroglu, F.

    1982-01-01

    Crushed glass and a Rhodamine B solution are used in a one-dimensional optically scanned column experiment to study the dispersion phenomenon in porous media. Results indicate that the described model gave satisfactory results and that the dispersion process in this experiment is basically convective. (DC)

  13. 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

  14. Dispersion and space charge

    NASA Astrophysics Data System (ADS)

    Venturini, Marco; Kishek, Rami A.; Reiser, Martin

    1998-11-01

    The presence of space charge affects the value of the dispersion function. On the other hand dispersion has a role in shaping the beam distribution and therefore in determining the resulting forces due to space charge. In this paper we present a framework where the interplay between space charge and dispersion for a continuous beam can be simultaneously treated. We revise the derivation of a new set of rms envelope-dispersion equations we have recently proposed in [1]. The new equations generalize the standard rms envelope equations currently used for matching to the case where bends and a longitudinal momentum spread are present. We report a comparison between the solutions of the rms envelope-dispersion equations and the results obtained using WARP, a Particle in Cell (PIC) code, in the modeling of the Maryland Electron Ring.

  15. Spawning areas of eastern Baltic cod revisited: Using hydrodynamic modelling to reveal spawning habitat suitability, egg survival probability, and connectivity patterns

    NASA Astrophysics Data System (ADS)

    Hinrichsen, H.-H.; Lehmann, A.; Petereit, C.; Nissling, A.; Ustups, D.; Bergström, U.; Hüssy, K.

    2016-04-01

    could appear as a barrier for the transport of Baltic cod eggs and yolk sac larvae and could potentially limit the connectivity of Baltic cod early life stages between the different basins in the western and eastern Baltic Sea. The possibility of an eastward directed transport up to the first-feeding larval stage exists only for eggs and yolk sac larvae at high buoyancy levels, suggesting that dispersal of early life stages between these spawning areas is limited.

  16. Habitat Suitability Index Models: Larval and Juvenile Red Drum

    USGS Publications Warehouse

    Buckley, Jack

    1984-01-01

    A review and synthesis of existing information were used to develop a habitat model for larval and juvenile red drum. The model is scaled to produce an index of habitat suitability between 0 (unsuitable habitat) and 1 (optimally suitable habitat) for estuarine areas along the Gulf of Mexico and Atlantic coasts. Habitat suitability indices are designed for use with habitat evaluation procedures developed by the U.S. Fish and Wildlife Service. Guidelines for model application and techniques for estimating model variables are provided.

  17. Oviposition and larval habitat preferences of the saltwater mosquito, Aedes vigilax, in a subtropical mangrove forest in Queensland, Australia.

    PubMed

    Knight, Jon; Griffin, Lachlan; Dale, Pat; Phinn, Stuart

    2012-01-01

    Our aim was to investigate the oviposition and larval habitats of the saltwater mosquito Aedes vigilax (Skuse) (Diptera: Culicidae) in a mangrove forest system in subtropical Queensland, Australia. Eggshells (indicators of oviposition) and larvae were sampled in three habitat classes that were depicted in a schematic model. Two classes were in depressions or basins, either with hummocks or dense pneumatophore substrates, both of which retained water after tidal flooding. The third class was in freely flushed mangroves that corresponded with more frequent tidal connections than the depression classes. ANOVA and Tukey-Kramer tests were used to analyze the data. The null hypotheses were rejected: the hummock class was a significant habitat based on both eggshell and larval data. The conclusion was that mosquito production in the mangrove system was distributed unevenly between habitat classes, and that the hummock class had conditions suited to the requirements of the immature stages of Ae. vigilax. This research has the potential to inform mosquito management strategies by focusing treatment on the problem habitats and underpinning habitat modifications including reducing water retention in the basins. PMID:22938052

  18. Oviposition and Larval Habitat Preferences of the Saltwater Mosquito, Aedes vigilax, in a Subtropical Mangrove Forest in Queensland, Australia

    PubMed Central

    Knight, Jon; Griffin, Lachlan; Dale, Pat; Phinn, Stuart

    2012-01-01

    Our aim was to investigate the oviposition and larval habitats of the saltwater mosquito Aedes vigilax (Skuse) (Diptera: Culicidae) in a mangrove forest system in subtropical Queensland, Australia. Eggshells (indicators of oviposition) and larvae were sampled in three habitat classes that were depicted in a schematic model. Two classes were in depressions or basins, either with hummocks or dense pneumatophore substrates, both of which retained water after tidal flooding. The third class was in freely flushed mangroves that corresponded with more frequent tidal connections than the depression classes. ANOVA and Tukey-Kramer tests were used to analyze the data. The null hypotheses were rejected: the hummock class was a significant habitat based on both eggshell and larval data. The conclusion was that mosquito production in the mangrove system was distributed unevenly between habitat classes, and that the hummock class had conditions suited to the requirements of the immature stages of Ae. vigilax. This research has the potential to inform mosquito management strategies by focusing treatment on the problem habitats and underpinning habitat modifications including reducing water retention in the basins. PMID:22938052

  19. Larvae from deep-sea methane seeps disperse in surface waters

    PubMed Central

    Arellano, Shawn M.; Van Gaest, Ahna L.; Johnson, Shannon B.; Vrijenhoek, Robert C.; Young, Craig M.

    2014-01-01

    Many species endemic to deep-sea methane seeps have broad geographical distributions, suggesting that they produce larvae with at least episodic long-distance dispersal. Cold-seep communities on both sides of the Atlantic share species or species complexes, yet larval dispersal across the Atlantic is expected to take prohibitively long at adult depths. Here, we provide direct evidence that the long-lived larvae of two cold-seep molluscs migrate hundreds of metres above the ocean floor, allowing them to take advantage of faster surface currents that may facilitate long-distance dispersal. We collected larvae of the ubiquitous seep mussel “Bathymodiolus” childressi and an associated gastropod, Bathynerita naticoidea, using remote-control plankton nets towed in the euphotic zone of the Gulf of Mexico. The timing of collections suggested that the larvae might disperse in the water column for more than a year, where they feed and grow to more than triple their original sizes. Ontogenetic vertical migration during a long larval life suggests teleplanic dispersal, a plausible explanation for the amphi-Atlantic distribution of “B.” mauritanicus and the broad western Atlantic distribution of B. naticoidea. These are the first empirical data to demonstrate a biological mechanism that might explain the genetic similarities between eastern and western Atlantic seep fauna. PMID:24827437

  20. Dispersion dipoles for coupled Drude oscillators

    NASA Astrophysics Data System (ADS)

    Odbadrakh, Tuguldur T.; Jordan, Kenneth D.

    2016-01-01

    We present the dispersion-induced dipole moments of coupled Drude oscillators obtained from two approaches. The first approach evaluates the dipole moment using the second-order Rayleigh-Schrödinger perturbation theory wave function allowing for dipole-dipole and dipole-quadrupole coupling. The second approach, based on response theory, employs an integral of the dipole-dipole polarizability of one oscillator and the dipole-dipole-quadrupole hyperpolarizability of the other oscillator over imaginary frequencies. The resulting dispersion dipoles exhibit an R-7 dependence on the separation between the two oscillators and are connected to the leading-order C6/R6 dispersion energy through the electrostatic Hellmann-Feynman theorem.

  1. Effect of three larval diets on larval development and male sexual performance of Anopheles gambiae s.s.

    PubMed

    Yahouédo, Gildas A; Djogbénou, Luc; Saïzonou, Jacques; Assogba, Bénoît S; Makoutodé, Michel; Gilles, Jeremie R L; Maïga, Hamidou; Mouline, Karine; Soukou, Bhonna K; Simard, Frédéric

    2014-04-01

    Population replacement/elimination strategies based on mass-release of sterile or otherwise genetically modified (male) mosquitoes are being considered in order to expand the malaria vector control arsenal on the way to eradication. A challenge in this context, is to produce male mosquitoes that will be able to compete and mate with wild females more efficiently than their wild counterparts, i.e. high fitness males. This study explored the effect of three larval food diets developed by the International Atomic Energy Agency on the overall fitness and mating performance of male Anopheles gambiae s.s. mosquitoes (Kisumu strain). Larval development (pupation and emergence rate, development time) was monitored, and adult wing length and energy reserves at emergence (i.e. lipids, sugars, glycogen and proteins) were measured. Male sexual performance was assessed through an insemination test whereby one male and 10 virgin females were maintained together in the same cage in order to record the number of inseminated females per 24h. Our results show that males reared on Diets 2 and 3 performed best during larval development. Males provided with treatment 2.2 had a shorter development time and performed best in insemination tests. However, these males had the lowest overall lifespan, suggesting a trade-off between longevity and sexual performances which needs to be taken into consideration when planning release. The results from this work were discussed in the context of sterile insect techniques or genetic control methods which is today one of the strategy in the overall mosquito control and elimination efforts. PMID:24291460

  2. Patterns and mechanisms of dispersal in a keystone seagrass species.

    PubMed

    Jahnke, Marlene; Christensen, Asbjørn; Micu, Dragos; Milchakova, Nataliya; Sezgin, Murat; Todorova, Valentina; Strungaru, Stefan; Procaccini, Gabriele

    2016-06-01

    Mechanisms and vectors of long-distance dispersal remain unknown for many coastal benthic species, including plants. Indications for the possibility for long-distance dispersal come from dispersal modelling and from genetic assessments, but have rarely been assessed with both methods. To this end, we assessed dispersal of the seagrass Zostera noltei, an important foundation species of the coastal zone. We investigate whether small scale seed dispersal and long-distance propagule dispersal do play a role for meta-population dynamics, using both genetic assessments based on eight microsatellite markers and physical modelling of ocean currents. Such assessments enhance our understanding of the biology and population dynamics of an important coastal foundation species. They are relevant for large scale conservation strategies as they give insights in the maintenance of genetic diversity and connectivity that may enhance resilience and resistance to stresses associated with seagrass loss. PMID:27085058

  3. Glycotope Sharing between Snail Hemolymph and Larval Schistosomes: Larval Transformation Products Alter Shared Glycan Patterns of Plasma Proteins

    PubMed Central

    Yoshino, Timothy P.; Wu, Xiao-Jun; Liu, Hongdi; Gonzalez, Laura A.; Deelder, André M.; Hokke, Cornelis H.

    2012-01-01

    Recent evidence supports the involvement of inducible, highly diverse lectin-like recognition molecules in snail hemocyte-mediated responses to larval Schistosoma mansoni. Because host lectins likely are involved in initial parasite recognition, we sought to identify specific carbohydrate structures (glycans) shared between larval S. mansoni and its host Biomphalaria glabrata to address possible mechanisms of immune avoidance through mimicry of elements associated with the host immunoreactivity. A panel of monoclonal antibodies (mABs) to specific S. mansoni glycans was used to identify the distribution and abundance of shared glycan epitopes (glycotopes) on plasma glycoproteins from B. glabrata strains that differ in their susceptibilities to infection by S. mansoni. In addition, a major aim of this study was to determine if larval transformation products (LTPs) could bind to plasma proteins, and thereby alter the glycotopes exposed on plasma proteins in a snail strain-specific fashion. Plasma fractions (<100 kDa/>100 kDa) from susceptible (NMRI) and resistant (BS-90) snail strains were subjected to SDS-PAGE and immunoblot analyses using mAB to LacdiNAc (LDN), fucosylated LDN variants, Lewis X and trimannosyl core glycans. Results confirmed a high degree of glycan sharing, with NMRI plasma exhibiting a greater distribution/abundance of LDN, F-LDN and F-LDN-F than BS-90 plasma (<100 kDa fraction). Pretreatment of blotted proteins with LTPs significantly altered the reactivity of specific mABs to shared glycotopes on blots, mainly through the binding of LTPs to plasma proteins resulting in either glycotope blocking or increased glycotope attachment to plasma. Many LTP-mediated changes in shared glycans were snail-strain specific, especially those in the <100 kDa fraction for NMRI plasma proteins, and for BS-90, mainly those in the >100 kDa fraction. Our data suggest that differential binding of S. mansoni LTPs to plasma proteins of susceptible and resistant B

  4. Glycotope sharing between snail hemolymph and larval schistosomes: larval transformation products alter shared glycan patterns of plasma proteins.

    PubMed

    Yoshino, Timothy P; Wu, Xiao-Jun; Liu, Hongdi; Gonzalez, Laura A; Deelder, André M; Hokke, Cornelis H

    2012-01-01

    Recent evidence supports the involvement of inducible, highly diverse lectin-like recognition molecules in snail hemocyte-mediated responses to larval Schistosoma mansoni. Because host lectins likely are involved in initial parasite recognition, we sought to identify specific carbohydrate structures (glycans) shared between larval S. mansoni and its host Biomphalaria glabrata to address possible mechanisms of immune avoidance through mimicry of elements associated with the host immunoreactivity. A panel of monoclonal antibodies (mABs) to specific S. mansoni glycans was used to identify the distribution and abundance of shared glycan epitopes (glycotopes) on plasma glycoproteins from B. glabrata strains that differ in their susceptibilities to infection by S. mansoni. In addition, a major aim of this study was to determine if larval transformation products (LTPs) could bind to plasma proteins, and thereby alter the glycotopes exposed on plasma proteins in a snail strain-specific fashion. Plasma fractions (< 100 kDa/> 100 kDa) from susceptible (NMRI) and resistant (BS-90) snail strains were subjected to SDS-PAGE and immunoblot analyses using mAB to LacdiNAc (LDN), fucosylated LDN variants, Lewis X and trimannosyl core glycans. Results confirmed a high degree of glycan sharing, with NMRI plasma exhibiting a greater distribution/abundance of LDN, F-LDN and F-LDN-F than BS-90 plasma (< 100 kDa fraction). Pretreatment of blotted proteins with LTPs significantly altered the reactivity of specific mABs to shared glycotopes on blots, mainly through the binding of LTPs to plasma proteins resulting in either glycotope blocking or increased glycotope attachment to plasma. Many LTP-mediated changes in shared glycans were snail-strain specific, especially those in the < 100 kDa fraction for NMRI plasma proteins, and for BS-90, mainly those in the > 100 kDa fraction. Our data suggest that differential binding of S. mansoni LTPs to plasma proteins of susceptible and resistant B

  5. Estimation of Dispersal Distances of Culex erraticus in a Focus of Eastern Equine Encephalitis Virus in the Southeastern United States

    PubMed Central

    Estep, Laura K.; Burkett-Cadena, Nathan D.; Hill, Geoffrey E.; Unnasch, Robert S.; Unnasch, Thomas R.

    2011-01-01

    Patterns of mosquito dispersal are important for predicting the risk of transmission of mosquito-borne pathogens to vertebrate hosts. We studied dispersal behavior of Culex erraticus (Dyar & Knab), a potentially significant vector of eastern equine encephalitis virus (EEEV) that is often associated with foci of this pathogen in the southeastern United States. Using data on the relative density of resting adult female Cx. erraticus around known emergence sites in Tuskegee National Forest, Alabama, we developed a model for the exponential decay of the relative density of adult mosquitoes with distance from larval habitats through parameterization of dispersal kernels. The mean and 99th percentile of dispersal distance for Cx. erraticus estimated from this model were 0.97 and 3.21 km per gonotrophic cycle, respectively. Parameterized dispersal kernels and estimates of the upper percentiles of dispersal distance of this species can potentially be used to predict EEEV infection risk in areas surrounding the Tuskegee National Forest focus in the event of an EEEV outbreak. The model that we develop for estimating the dispersal distance of Cx. erraticus from collections of adult mosquitoes could be applicable to other mosquito species that emerge from discrete larval sites. PMID:21175044

  6. Proteomic analysis through larval development of Solea senegalensis flatfish.

    PubMed

    Chicano-Gálvez, Eduardo; Asensio, Esther; Cañavate, José Pedro; Alhama, José; López-Barea, Juan

    2015-12-01

    The post-embryonic development of the Senegalese sole, Solea senegalensis, a flatfish of growing interest in fisheries and aquaculture, is associated with drastic morpho-physiological changes during metamorphosis. Although in the last two decades knowledge on sole culture has notably increased, especially in Southern Europe, its progress was restricted due to lack of methods to control reproduction, improve larval quality and increase juvenile disease resistance. A limited knowledge of the physiological, molecular and genetic mechanisms involved is at the base of such limitation. A proteomic study was carried out to explore the molecular events that occur during S. senegalensis ontogenesis. Protein expression changes were monitored in larvae from 5 to 21 dph by combining 2DE and protein identification with de novo MS/MS sequencing. An average of 6177 ± 282 spots was resolved in 2DE gels. Hierarchical cluster analysis of the 705 selected spots grouped them in eight patterns. Thirty-four proteins were identified and assigned biological functions including structure, metabolism highlighting energy metabolism, transport, protein folding, stress response, chromatin organization and regulation of gene expression. These changes provide a sequential description of the molecular events associated with the biochemical and biological transformations that occur during sole larval development. PMID:26365915

  7. Small nonnative fishes as predators of larval razorback suckers

    USGS Publications Warehouse

    Carpenter, J.; Mueller, G.A.

    2008-01-01

    The razorback sucker (Xyrauchen texanus), an endangered big-river fish of the Colorado River basin, has demonstrated no sustainable recruitment in 4 decades, despite presence of spawning adults and larvae. Lack of adequate recruitment has been attributed to several factors, including predation by nonnative fishes. Substantial funding and effort has been expended on mechanically removing nonnative game fishes, typically targeting large predators. As a result, abundance of larger predators has declined, but the abundance of small nonnative fishes has increased in some areas. We conducted laboratory experiments to determine if small nonnative fishes would consume larval razorback suckers. We tested adults of three small species (threadfin shad, Dorosoma petenense; red shiner, Cyprinella lutrensis; fathead minnow, Pimephales promelas) and juveniles of six larger species (common carp, Cyprinus carpio; yellow bullhead, Ameiurus natalis; channel catfish, Ictalurus punctatus; rainbow trout, Oncorhynchus mykiss; green sunfish, Lepomis cyanellus; bluegill, L. macrochirus). These nonnative fishes span a broad ecological range and are abundant within the historical range of the razorback sucker. All nine species fed on larval razorback suckers (total length, 9-16 mm). Our results suggest that predation by small nonnative fishes could be responsible for limiting recovery of this endangered species.

  8. Standardized Laboratory Feeding of Larval Aedes japonicus japonicus (Diptera: Culicidae)

    PubMed Central

    Bock, Friederike; Kuch, Ulrich; Pfenninger, Markus; Müller, Ruth

    2015-01-01

    The Asian bush mosquito (Aedes japonicus japonicus, Theobald 1901) is an invasive culicid species which originates in Asia but is nowadays present in northern America and Europe. It is a competent vector for several human disease pathogens. In addition to the public health threat, this invasive species may also be an ecological threat for native container-breeding mosquitoes which share a similar larval habitat. Therefore, it is of importance to gain knowledge on ecological and eco-toxicological features of the Asian bush mosquito. However, optimal laboratory feeding conditions have not yet been established. Standardized feeding methods will be needed in assessing the impact of insecticides or competitional strength of this species. To fill this gap, we performed experiments on food quality and quantity for Ae. j. japonicus larvae. We found out that the commercial fish food TetraMin (Tetra, Melle, Germany) in a dose of 10 mg per larva is the most suitable food tested. We also suggest a protocol with a feeding sequence of seven portions for all larval stages of this species. PMID:26452522

  9. Resource Limitation, Controphic Ostracod Density and Larval Mosquito Development

    PubMed Central

    Rowbottom, Raylea; Carver, Scott; Barmuta, Leon A.; Weinstein, Philip; Foo, Dahlia; Allen, Geoff R.

    2015-01-01

    Aquatic environments can be restricted with the amount of available food resources especially with changes to both abiotic and biotic conditions. Mosquito larvae, in particular, are sensitive to changes in food resources. Resource limitation through inter-, and intra-specific competition among mosquitoes are known to affect both their development and survival. However, much less is understood about the effects of non-culicid controphic competitors (species that share the same trophic level). To address this knowledge gap, we investigated and compared mosquito larval development, survival and adult size in two experiments, one with different densities of non-culicid controphic conditions and the other with altered resource conditions. We used Aedes camptorhynchus, a salt marsh breeding mosquito and a prominent vector for Ross River virus in Australia. Aedes camptorhynchus usually has few competitors due to its halo-tolerance and distribution in salt marshes. However, sympatric ostracod micro-crustaceans often co-occur within these salt marshes and can be found in dense populations, with field evidence suggesting exploitative competition for resources. Our experiments demonstrate resource limiting conditions caused significant increases in mosquito developmental times, decreased adult survival and decreased adult size. Overall, non-culicid exploitation experiments showed little effect on larval development and survival, but similar effects on adult size. We suggest that the alterations of adult traits owing to non-culicid controphic competition has potential to extend to vector-borne disease transmission. PMID:26558896

  10. An electric beam trawl for the capture of larval lampreys

    USGS Publications Warehouse

    McLain, Alberton; Dahl, Frederick H.

    1968-01-01

    The chemicals used to control the sea lamprey, Petromyzon marinus, in the Great Lakes have drastically reduced populations of larval lampreys in tributary streams. These larvicides are too costly and difficult to apply, however, in inland lakes, estuaries, and bays. Populations of sea lampreys in these areas constitute a threat to the refinement of the control. The gear available to locate, ample, and evaluate larval populations in deep water are inefficient. Electric shockers, satisfactory for collecting ammocoetes in streams, are limited to shallow water. The use of mechanical devices such as the Petersen dredge, anchor dredge, and the orange-peel dredge is time consuming, inefficient, and relatively ineffective in providing reliable quantitative evaluation of population size and composition over large areas of bottom. A device was required to sample adequately many areas in a short period of time, regardless of the depth of water. Mobility also was essential to permit operation of the unit in the various Great Lakes and in inland waters. An electrified beam trawl has been developed that most nearly meets these requirements. It has been used successfully to collect larvae of the sea lamprey, American brook lamprey (Lampetra lamottei), northern brook lamprey (Ichthyomyzon fossor), and silver lamprey (I. unicuspis). Effectiveness of the trawl did not appear to differ with species.

  11. FACS purification of Drosophila larval Neuroblasts for next generation sequencing

    PubMed Central

    Conder, Ryan; Schmauss, Gerald; Knoblich, Juergen A.

    2014-01-01

    Elegant tools are available for the genetic analysis of neural stem cell lineages in Drosophila, but a methodology for purifying stem cells and their differentiated progeny for transcriptome analysis is currently missing. Previous attempts to overcome this problem either involved using RNA isolated from whole larval brain tissue or co-transcriptional in vivo mRNA tagging. As both methods have limited cell type specificity, we developed a protocol for the isolation of Drosophila neural stem cells (neuroblasts, NBs) and their differentiated sibling cells by FACS. We dissected larval brains from fly strains expressing GFP under the control of a NB lineage-specific GAL4 line. Upon dissociation, we made use of differences in GFP intensity and cell size to separate NBs and neurons. The resulting cell populations are over 98% pure and can readily be used for live imaging or gene expression analysis. Our method is optimized for neural stem cells, but it can also be applied to other Drosophila cell types. Primary cell suspensions and sorted cell populations can be obtained within 1 d; material for deep-sequencing library preparation can be obtained within 4 d. PMID:23660757

  12. Standardized Laboratory Feeding of Larval Aedes japonicus japonicus (Diptera: Culicidae).

    PubMed

    Bock, Friederike; Kuch, Ulrich; Pfenninger, Markus; Müller, Ruth

    2015-01-01

    The Asian bush mosquito (Aedes japonicus japonicus, Theobald 1901) is an invasive culicid species which originates in Asia but is nowadays present in northern America and Europe. It is a competent vector for several human disease pathogens. In addition to the public health threat, this invasive species may also be an ecological threat for native container-breeding mosquitoes which share a similar larval habitat. Therefore, it is of importance to gain knowledge on ecological and eco-toxicological features of the Asian bush mosquito. However, optimal laboratory feeding conditions have not yet been established. Standardized feeding methods will be needed in assessing the impact of insecticides or competitional strength of this species. To fill this gap, we performed experiments on food quality and quantity for Ae. j. japonicus larvae. We found out that the commercial fish food TetraMin (Tetra, Melle, Germany) in a dose of 10 mg per larva is the most suitable food tested. We also suggest a protocol with a feeding sequence of seven portions for all larval stages of this species. PMID:26452522

  13. Resource Limitation, Controphic Ostracod Density and Larval Mosquito Development.

    PubMed

    Rowbottom, Raylea; Carver, Scott; Barmuta, Leon A; Weinstein, Philip; Foo, Dahlia; Allen, Geoff R

    2015-01-01

    Aquatic environments can be restricted with the amount of available food resources especially with changes to both abiotic and biotic conditions. Mosquito larvae, in particular, are sensitive to changes in food resources. Resource limitation through inter-, and intra-specific competition among mosquitoes are known to affect both their development and survival. However, much less is understood about the effects of non-culicid controphic competitors (species that share the same trophic level). To address this knowledge gap, we investigated and compared mosquito larval development, survival and adult size in two experiments, one with different densities of non-culicid controphic conditions and the other with altered resource conditions. We used Aedes camptorhynchus, a salt marsh breeding mosquito and a prominent vector for Ross River virus in Australia. Aedes camptorhynchus usually has few competitors due to its halo-tolerance and distribution in salt marshes. However, sympatric ostracod micro-crustaceans often co-occur within these salt marshes and can be found in dense populations, with field evidence suggesting exploitative competition for resources. Our experiments demonstrate resource limiting conditions caused significant increases in mosquito developmental times, decreased adult survival and decreased adult size. Overall, non-culicid exploitation experiments showed little effect on larval development and survival, but similar effects on adult size. We suggest that the alterations of adult traits owing to non-culicid controphic competition has potential to extend to vector-borne disease transmission. PMID:26558896

  14. System for maintaining sediment suspensions during larval fish studies

    USGS Publications Warehouse

    Chilton, E.W., II

    1991-01-01

    A new system was developed for maintaining suspensions of inorganic solids during laboratory studies on early life stages of fish. Microfine bentonite was successfully held in suspension in specially constructed units during a 21-d fishless test, a 28-d experiment with juvenile green sunfish (lepomis cyanellus), and four shorter experiments (5-9 d) with four species of larval fishes, white sucker (catostomus commersoni), northern pike (esox lucius), channel catfish (ictalurus punctatus), and walleye (stizostedion vitreum). Each experiment on larval fish was conducted until the yolk-sac had been absorbed. Concentrations of bentonite ranged from 0 to 728 mg/l. Each unit consisted of a holding chamber set in a stainless steel bowl and two submersible pumps that recirculated the suspension. Turbidity readings remained nearly constant throughout each experiment. Because the turbidity of suspensions was well correlated with bentonite concentration (r2 = 0.989) And easy to measure, turbidity was used as an indicator of concentration. The system is inexpensive, easy to assemble, and does not require a diluter system to maintain constant concentrations of suspended material.

  15. Influence of a dispersant on the bioaccumulation of phenanthrene by topsmelt (Atherinops affinis).

    PubMed

    Mielbrecht, E E; Wolfe, M F; Tjeerdema, R S; Sowby, M L

    2005-05-01

    Chemical dispersants enhance oil spill dispersion by forming water-accommodated micelles with oil droplets. However, how dispersants alter bioavailability and subsequent bioaccumulation of hydrocarbons is not well understood. Thus, the goal was to investigate the influence of a chemical dispersant on the disposition (uptake, biotransformation, and depuration) of a model hydrocarbon, [14C]-phenanthrene ([14C]PHN), by larval topsmelt (Atherinops affinis). Exposure was via aqueous-only or combined dietary and aqueous routes from a water-accommodated fraction (WAF) of Prudhoe Bay Crude Oil (PBCO) or a WAF of Corexit 9527-dispersed PBCO (DO). Trophic transfer was measured by incorporating into exposure media both a rotifer (Brachionus plicatilis) as food for the fish and a phytoplankton (Isochrysis galbana) as food for the rotifers. Short-term (4 h) bioconcentration of PHN was significantly decreased in topsmelt when oil was treated with dispersant (P < 0.05), but differences diminished after 12 h. When trophic transfer was incorporated, PHN accumulation was initially delayed but after 12 h attained similar levels. Dispersant use also significantly decreased the proportion of biotransformed PHN (as 9-phenanthrylsulfate) produced by topsmelt (P < 0.05). However, overall PHN depuration was not affected by dispersant use. Thus, chemical dispersant use in oil spill response may reduce short-term uptake but not long-term accumulation of hydrocarbons such as PHN in pelagic fish. PMID:15814309

  16. The Regional Patterns of Chemical Composition in the Otolith Core of Larval Fish

    NASA Astrophysics Data System (ADS)

    Chang, M. Y.; Geffen, A. J.; Nash, R. D. M.; Clemmesen, C.

    2012-04-01

    juveniles from western Irish Sea and the Stanton Bank contributed most to the spawning populations. The otolith signature (without length-at-age information) indicated that the North Sea larvae contributed mostly to the spawning herring from the Dingle and the Cape Wrath. The results suggested that there might be different current systems, which drove the larval dispersal both northward and southward from the spawning ground to the North Sea. Although there might be mixtures and interconnections among the west coast herrings, which resulted in the similar otolith chemical signals, the otolith chemical composition still provided useful information of regional differences for tracing back the origin of spawning populations. The detailed current system may be needed to provide more inference for the larval dispersal and the linkage between nursery-ground and spawning populations. * present address: Biodiversity Research Center, Academia Sinica, Taiwan, R.O.C.

  17. Position of Larval Tapeworms, Polypocephalus sp., in the Ganglia of Shrimp, Litopenaeus setiferus

    PubMed Central

    Carreon, Nadia; Faulkes, Zen

    2014-01-01

    Parasites that invade the nervous system of their hosts have perhaps the best potential to manipulate their host’s behavior, but how they manipulate the host, if they do at all, could depend on their position within the host’s nervous system. We hypothesize that parasites that live in the nervous system of their host will be randomly distributed if they exert their influence through non-specific effects (i.e., general pathology), but that their position in the nervous system will be non-random if they exert their influence by targeting specific neural circuits. We recorded the position of larval tapeworms, Polypocephalus sp., in the abdominal ganglia of white shrimp, Litopenaeus setiferus. Tapeworms are more common within ganglia than in the section of the nerve cord between ganglia, even though the nerve cord has a greater volume than the ganglia. The tapeworms are also more abundant in the periphery of the ganglia. Because most synaptic connections are within the central region of the ganglion, such positioning may represent a trade-off between controlling the nervous system and damaging it. PMID:24820854

  18. Effect of ace inhibitors and TMOF on growth, development, and trypsin activity of larval Spodoptera littoralis.

    PubMed

    Lemeire, Els; Borovsky, Dov; Van Camp, John; Smagghe, Guy

    2008-12-01

    Angiotensin converting enzyme (ACE) is a zinc metallopeptidase capable of cleaving dipeptide or dipeptideamide moieties at the C-terminal end of peptides. ACE is present in the hemolymph and reproductive tissues of insects. The presence of ACE in the hemolymph and its broad substrate specificity suggests an important role in processing of bioactive peptides. This study reports the effects of ACE inhibitors on larval growth in the cotton leafworm Spodoptera littoralis. Feeding ACE inhibitors ad lib decreased the growth rate, inhibited ACE activity in the larval hemolymph, and down-regulated trypsin activity in the larval gut. These results indicate that S. littoralis ACE may influence trypsin biosynthesis in the larval gut by interacting with a trypsin-modulating oostatic factor (TMOF). Injecting third instar larvae with a combination of Aea-TMOF and the ACE inhibitor captopril, down-regulated trypsin biosynthesis in the larval gut indicating that an Aea-TMOF gut receptor analogue could be present. Injecting captopril and enalapril into newly molted fifth instar larvae stopped larval feeding and decreased weight gain. Together, these results indicate that ACE inhibitors are efficacious in stunting larval growth and ACE plays an important role in larval growth and development. PMID:18949805

  19. Evaluation of waste artificial larval rearing media as oviposition attractant for New World screwworm (Diptera: Calliphoridae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The waste artificial larval rearing media of the New World Screwworm, Cochliomyia hominivorax (Coquerel) were evaluated to determine their effectiveness as oviposition attractants. Various concentrations of waste larval media resulting from rearing screwworm larvae in gel and cellulose fiber-based ...

  20. Ascorbic Acid Influences the Development and Immunocompetence of Larval Heliothis virescens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report that ascorbic acid, which is known to be a free radical scavenger, to be important not only in insect development but also in larval resistance to baculovirus infection. We sequentially elevated the ascorbic acid content in diet and evaluated the effect on larval H. virescens development ...

  1. Influences of acid mine drainage and thermal enrichment on stream fish reproduction and larval survival

    USGS Publications Warehouse

    Hafs, Andrew W.; Horn, C.D.; Mazik, P.M.; Hartman, K.J.

    2010-01-01

    Potential effects of acid mine drainage (AMD) and thermal enrichment on the reproduction of fishes were investigated through a larval-trapping survey in the Stony River watershed, Grant County, WV. Trapping was conducted at seven sites from 26 March to 2 July 2004. Overall larval catch was low (379 individuals in 220 hours of trapping). More larval White Suckers were captured than all other species. Vectors fitted to nonparametric multidimensional scaling ordinations suggested that temperature was highly correlated to fish communities captured at our sites. Survival of larval Fathead Minnows was examined in situ at six sites from 13 May to 11 June 2004 in the same system. Larval survival was lower, but not significantly different between sites directly downstream of AMD-impacted tributaries (40% survival) and non-AMD sites (52% survival). The lower survival was caused by a significant mortality event at one site that coincided with acute pH depression in an AMD tributary immediately upstream of the site. Results from a Cox proportional hazard test suggests that low pH is having a significant negative influence on larval fish survival in this system. The results from this research indicate that the combination of low pH events and elevated temperature are negatively influencing the larval fish populations of the Stony River watershed. Management actions that address these problems would have the potential to substantially increase both reproduction rates and larval survival, therefore greatly enhancing the fishery.

  2. The effect of larval density on adult demographic traits in Ambystoma opacum

    SciTech Connect

    Scott, D.E. )

    1994-07-01

    Factors that affect traits of aquatic larvae of amphibians may have long-lasting effects on terrestrial juveniles and adults. I manipulated larval densities of marbled salamanders, Ambystoma opacum, in large-scale field enclosures during 2 yr, released the juveniles that metamorphosed from these enclosures, and tested for effects on adults that returned to the pond during 6-7 subsequent breeding seasons. Individuals from low larval density treatments tended to have greater lipid stores at metamorphosis than those from high densities and survived longer in a laboratory inanition study. In the field, individuals that experienced low larval density returned for their first reproductive bout as larger adults than those from high-density treatments. For 5-yr-old females released in 1986, low larval density was linked to greater clutch size; clutch size in 4-yr-old animals from the 1987 cohort did not differ between larval treatment groups. Larval density also influenced age at first reproduction, as animals rared at low densities returned to breed at younger ages. Averaged across both cohorts, the proportion of animals that returned to breed at least once was 21% for low-density groups compared to 6% for the high density groups. The larval environment exerted a strong influence on postmetamorphic traits, and thus larval density likely plays an important role of population regulation in both the aquatic and terrestrial phase of the life cycle. 81 refs., 4 figs., 6 tabs.

  3. Dispersion strengthened copper

    DOEpatents

    Sheinberg, Haskell; Meek, Thomas T.; Blake, Rodger D.

    1990-01-01

    A composition of matter comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide, and a method for making this composition of matter.

  4. Dispersion strengthened copper

    DOEpatents

    Sheinberg, Haskell; Meek, Thomas T.; Blake, Rodger D.

    1989-01-01

    A composition of matter comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide, and a method for making this composition of matter.

  5. Dendritic connectivity controls biodiversity patterns in experimental metacommunities

    PubMed Central

    Carrara, Francesco; Altermatt, Florian; Rodriguez-Iturbe, Ignacio; Rinaldo, Andrea

    2012-01-01

    Biological communities often occur in spatially structured habitats where connectivity directly affects dispersal and metacommunity processes. Recent theoretical work suggests that dispersal constrained by the connectivity of specific habitat structures, such as dendrites like river networks, can explain observed features of biodiversity, but direct evidence is still lacking. We experimentally show that connectivity per se shapes diversity patterns in microcosm metacommunities at different levels. Local dispersal in isotropic lattice landscapes homogenizes local species richness and leads to pronounced spatial persistence. On the contrary, dispersal along dendritic landscapes leads to higher variability in local diversity and among-community composition. Although headwaters exhibit relatively lower species richness, they are crucial for the maintenance of regional biodiversity. Our results establish that spatially constrained dendritic connectivity is a key factor for community composition and population persistence. PMID:22460788

  6. A larval key to the Drusinae species (Trichoptera: Limnephilidae) of Austria, Germany, Switzerland and the dinaric western Balkan1

    PubMed Central

    Waringer, J.; Graf, W.; Pauls, S.U.; Previšić, A.; Kučinić, M.

    2016-01-01

    A larval key of the Drusinae of Central Europe and the dinaric western Balkan is presented. Phylogeographic relationships are discussed in the light of molecular genetics, feeding ecology and larval morphology. PMID:26985170

  7. Nanocrystal dispersed amorphous alloys

    NASA Technical Reports Server (NTRS)

    Perepezko, John H. (Inventor); Allen, Donald R. (Inventor); Foley, James C. (Inventor)

    2001-01-01

    Compositions and methods for obtaining nanocrystal dispersed amorphous alloys are described. A composition includes an amorphous matrix forming element (e.g., Al or Fe); at least one transition metal element; and at least one crystallizing agent that is insoluble in the resulting amorphous matrix. During devitrification, the crystallizing agent causes the formation of a high density nanocrystal dispersion. The compositions and methods provide advantages in that materials with superior properties are provided.

  8. Larval therapy from antiquity to the present day: mechanisms of action, clinical applications and future potential

    PubMed Central

    Whitaker, Iain S; Twine, Christopher; Whitaker, Michael J; Welck, Mathew; Brown, Charles S; Shandall, Ahmed

    2007-01-01

    When modern medicine fails, it is often useful to draw ideas from ancient treatments. The therapeutic use of fly larvae to debride necrotic tissue, also known as larval therapy, maggot debridement therapy or biosurgery, dates back to the beginnings of civilisation. Despite repeatedly falling out of favour largely because of patient intolerance to the treatment, the practice of larval therapy is increasing around the world because of its efficacy, safety and simplicity. Clinical indications for larval treatment are varied, but, in particular, are wounds infected with multidrug‐resistant bacteria and the presence of significant co‐morbidities precluding surgical intervention. The flies most often used in larval therapy are the facultative calliphorids, with the greenbottle blowfly (Lucilia sericata) being the most widely used species. This review summarises the fascinating and turbulent history of larval therapy from its origin to the present day, including mechanisms of action and evidence for its clinical applications. It also explores future research directions. PMID:17551073

  9. [Relationships among Cyrtotrachelus buqueti larval density and wormhole number and bamboo shoot damage degree].

    PubMed

    Yang, Yao-Jun; Wang, Shu-Fang; Gong, Jia-Wen; Liu, Chao; Mu, Chi; Qin, Hong

    2009-08-01

    In August of 2007 and 2008, a field investigation was made to study the relationships among Cyrtotrachelus buqueti larval density and wormhole number and bamboo shoot damage degree in Sichuan Province. The three pairs of variables, i. e., C. buqueti larval density and wormhole number, C. buqueti larval density and bamboo shoot damage degree, and C. buqueti wormhole number and bamboo shoot damage degree, fitted cubic equations well, with the correlation coefficients at P = 0.001. Based on these mathematical models, the forecast tables for C. buqueti larval density and bamboo shoot damage degree were established, and the thresholds of C. buqueti larval density and wormhole number were 0.13 and 0.40 individual per bamboo, respectively. PMID:19947221

  10. Wind direction and proximity to larval sites determines malaria risk in Kilifi District in Kenya

    PubMed Central

    Midega, Janet T.; Smith, Dave L.; Olotu, Ally; Mwangangi, Joseph M.; Nzovu, Joseph G.; Wambua, Juliana; Nyangweso, George; Mbogo, Charles M.; Christophides, George K.; Marsh, Kevin; Bejon, Philip

    2012-01-01

    Studies of the fine-scale spatial epidemiology of malaria consistently identify malaria hotspots, comprising clusters of homesteads at high transmission intensity. These hotspots sustain transmission, and may be targeted by malaria-control programmes. Here we describe the spatial relationship between the location of Anopheles larval sites and human malaria infection in a cohort study of 642 children, aged 1–10-years-old. Our data suggest that proximity to larval sites predict human malaria infection, when homesteads are upwind of larval sites, but not when homesteads are downwind of larval sites. We conclude that following oviposition, female Anophelines fly upwind in search for human hosts and, thus, malaria transmission may be disrupted by targeting vector larval sites in close proximity, and downwind to malaria hotspots. PMID:22334077

  11. Fickian dispersion is anomalous

    SciTech Connect

    Cushman, John H.; O’Malley, Dan

    2015-06-22

    The thesis put forward here is that the occurrence of Fickian dispersion in geophysical settings is a rare event and consequently should be labeled as anomalous. What people classically call anomalous is really the norm. In a Lagrangian setting, a process with mean square displacement which is proportional to time is generally labeled as Fickian dispersion. With a number of counter examples we show why this definition is fraught with difficulty. In a related discussion, we show an infinite second moment does not necessarily imply the process is super dispersive. By employing a rigorous mathematical definition of Fickian dispersion we illustrate why it is so hard to find a Fickian process. We go on to employ a number of renormalization group approaches to classify non-Fickian dispersive behavior. Scaling laws for the probability density function for a dispersive process, the distribution for the first passage times, the mean first passage time, and the finite-size Lyapunov exponent are presented for fixed points of both deterministic and stochastic renormalization group operators. The fixed points of the renormalization group operators are p-self-similar processes. A generalized renormalization group operator is introduced whose fixed points form a set of generalized self-similar processes. Finally, power-law clocks are introduced to examine multi-scaling behavior. Several examples of these ideas are presented and discussed.

  12. Fickian dispersion is anomalous

    DOE PAGESBeta

    Cushman, John H.; O’Malley, Dan

    2015-06-22

    The thesis put forward here is that the occurrence of Fickian dispersion in geophysical settings is a rare event and consequently should be labeled as anomalous. What people classically call anomalous is really the norm. In a Lagrangian setting, a process with mean square displacement which is proportional to time is generally labeled as Fickian dispersion. With a number of counter examples we show why this definition is fraught with difficulty. In a related discussion, we show an infinite second moment does not necessarily imply the process is super dispersive. By employing a rigorous mathematical definition of Fickian dispersion wemore » illustrate why it is so hard to find a Fickian process. We go on to employ a number of renormalization group approaches to classify non-Fickian dispersive behavior. Scaling laws for the probability density function for a dispersive process, the distribution for the first passage times, the mean first passage time, and the finite-size Lyapunov exponent are presented for fixed points of both deterministic and stochastic renormalization group operators. The fixed points of the renormalization group operators are p-self-similar processes. A generalized renormalization group operator is introduced whose fixed points form a set of generalized self-similar processes. Finally, power-law clocks are introduced to examine multi-scaling behavior. Several examples of these ideas are presented and discussed.« less

  13. Correlated Evolution between Mode of Larval Development and Habitat in Muricid Gastropods

    PubMed Central

    Pappalardo, Paula; Rodríguez-Serrano, Enrique; Fernández, Miriam

    2014-01-01

    Abstract Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule), which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding) development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in muricids

  14. Correlated evolution between mode of larval development and habitat in muricid gastropods.

    PubMed

    Pappalardo, Paula; Rodríguez-Serrano, Enrique; Fernández, Miriam

    2014-01-01

    Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule), which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding) development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in muricids gastropods

  15. Looking for hotspots of marine metacommunity connectivity: a methodological framework.

    PubMed

    Melià, Paco; Schiavina, Marcello; Rossetto, Marisa; Gatto, Marino; Fraschetti, Simonetta; Casagrandi, Renato

    2016-01-01

    Seascape connectivity critically affects the spatiotemporal dynamics of marine metacommunities. Understanding how connectivity patterns emerge from physically and biologically-mediated interactions is therefore crucial to conserve marine ecosystem functions and biodiversity. Here, we develop a set of biophysical models to explore connectivity in assemblages of species belonging to a typical Mediterranean community (Posidonia oceanica meadows) and characterized by different dispersing traits. We propose a novel methodological framework to synthesize species-specific results into a set of community connectivity metrics and show that spatiotemporal variation in magnitude and direction of the connections, as well as interspecific differences in dispersing traits, are key factors structuring community connectivity. We eventually demonstrate how these metrics can be used to characterize the functional role of each marine area in determining patterns of community connectivity at the basin level and to support marine conservation planning. PMID:27029563

  16. Looking for hotspots of marine metacommunity connectivity: a methodological framework

    NASA Astrophysics Data System (ADS)

    Melià, Paco; Schiavina, Marcello; Rossetto, Marisa; Gatto, Marino; Fraschetti, Simonetta; Casagrandi, Renato

    2016-03-01

    Seascape connectivity critically affects the spatiotemporal dynamics of marine metacommunities. Understanding how connectivity patterns emerge from physically and biologically-mediated interactions is therefore crucial to conserve marine ecosystem functions and biodiversity. Here, we develop a set of biophysical models to explore connectivity in assemblages of species belonging to a typical Mediterranean community (Posidonia oceanica meadows) and characterized by different dispersing traits. We propose a novel methodological framework to synthesize species-specific results into a set of community connectivity metrics and show that spatiotemporal variation in magnitude and direction of the connections, as well as interspecific differences in dispersing traits, are key factors structuring community connectivity. We eventually demonstrate how these metrics can be used to characterize the functional role of each marine area in determining patterns of community connectivity at the basin level and to support marine conservation planning.

  17. Looking for hotspots of marine metacommunity connectivity: a methodological framework

    PubMed Central

    Melià, Paco; Schiavina, Marcello; Rossetto, Marisa; Gatto, Marino; Fraschetti, Simonetta; Casagrandi, Renato

    2016-01-01

    Seascape connectivity critically affects the spatiotemporal dynamics of marine metacommunities. Understanding how connectivity patterns emerge from physically and biologically-mediated interactions is therefore crucial to conserve marine ecosystem functions and biodiversity. Here, we develop a set of biophysical models to explore connectivity in assemblages of species belonging to a typical Mediterranean community (Posidonia oceanica meadows) and characterized by different dispersing traits. We propose a novel methodological framework to synthesize species-specific results into a set of community connectivity metrics and show that spatiotemporal variation in magnitude and direction of the connections, as well as interspecific differences in dispersing traits, are key factors structuring community connectivity. We eventually demonstrate how these metrics can be used to characterize the functional role of each marine area in determining patterns of community connectivity at the basin level and to support marine conservation planning. PMID:27029563

  18. Biocontrol of larval mosquitoes by Acilius sulcatus (Coleoptera: Dytiscidae)

    PubMed Central

    Chandra, Goutam; Mandal, Samir K; Ghosh, Arup K; Das, Dipanwita; Banerjee, Siddhartha S; Chakraborty, Sumanta

    2008-01-01

    Background Problems associated with resistant mosquitoes and the effects on non-target species by chemicals, evoke a reason to find alternative methods to control mosquitoes, like the use of natural predators. In this regard, aquatic coleopterans have been explored less compared to other insect predators. In the present study, an evaluation of the role of the larvae of Acilius sulcatus Linnaeus 1758 (Coleoptera: Dytiscidae) as predator of mosquito immatures was made in the laboratory. Its efficacy under field condition was also determined to emphasize its potential as bio-control agent of mosquitoes. Methods In the laboratory, the predation potential of the larvae of A. sulcatus was assessed using the larvae of Culex quinquefasciatus Say 1823 (Diptera: Culicidae) as prey at varying predator and prey densities and available space. Under field conditions, the effectiveness of the larvae of A. sulcatus was evaluated through augmentative release in ten cemented tanks hosting immatures of different mosquito species at varying density. The dip density changes in the mosquito immatures were used as indicator for the effectiveness of A. sulcatus larvae. Results A single larva of A. sulcatus consumed on an average 34 IV instar larvae of Cx. quinquefasciatus in a 24 h period. It was observed that feeding rate of A. sulcatus did not differ between the light-on (6 a.m. – 6 p.m.), and dark (6 p.m. – 6 a.m.) phases, but decreased with the volume of water i.e., space availability. The prey consumption of the larvae of A. sulcatus differed significantly (P < 0.05) with different prey, predator and volume combinations, revealed through univariate ANOVA. The field study revealed a significant decrease (p < 0.05) in larval density of different species of mosquitoes after 30 days from the introduction of A. sulcatus larvae, while with the withdrawal, a significant increase (p < 0.05) in larval density was noted indicating the efficacy of A. sulcatus in regulating mosquito

  19. When is dispersal for dispersal? Unifying marine and terrestrial perspectives.

    PubMed

    Burgess, Scott C; Baskett, Marissa L; Grosberg, Richard K; Morgan, Steven G; Strathmann, Richard R

    2016-08-01

    Recent syntheses on the evolutionary causes of dispersal have focused on dispersal as a direct adaptation, but many traits that influence dispersal have other functions, raising the question: when is dispersal 'for' dispersal? We review and critically evaluate the ecological causes of selection on traits that give rise to dispersal in marine and terrestrial organisms. In the sea, passive dispersal is relatively easy and specific morphological, behavioural, and physiological adaptations for dispersal are rare. Instead, there may often be selection to limit dispersal. On land, dispersal is relatively difficult without specific adaptations, which are relatively common. Although selection for dispersal is expected in both systems and traits leading to dispersal are often linked to fitness, systems may differ in the extent to which dispersal in nature arises from direct selection for dispersal or as a by-product of selection on traits with other functions. Our analysis highlights incompleteness of theories that assume a simple and direct relationship between dispersal and fitness, not just insofar as they ignore a vast array of taxa in the marine realm, but also because they may be missing critically important effects of traits influencing dispersal in all realms. PMID:26118564

  20. The simple fly larval visual system can process complex images.

    PubMed

    Justice, Elizabeth Daubert; Macedonia, Nicholas James; Hamilton, Catherine; Condron, Barry

    2012-01-01

    Animals that have simple eyes are thought to only detect crude visual detail such as light level. However, predatory insect larvae using a small number of visual inputs seem to distinguish complex image targets. Here we show that Drosophila melanogaster larvae, which have 12 photoreceptor cells per hemisphere, are attracted to distinct motions of other, tethered larvae and that this recognition requires the visual system but not the olfactory system. In addition, attraction to tethered larvae still occurs across a clear plastic barrier, does not occur significantly in the dark and attraction occurs to a computer screen movie of larval motion. By altering the artificial attractant movie, we conclude that visual recognition involves both spatial and temporal components. Our results demonstrate that a simple but experimentally tractable visual system can distinguish complex images and that processing in the relatively large central brain may compensate for the simple input. PMID:23093193

  1. Neural Circuits Underlying Visually Evoked Escapes in Larval Zebrafish.

    PubMed

    Dunn, Timothy W; Gebhardt, Christoph; Naumann, Eva A; Riegler, Clemens; Ahrens, Misha B; Engert, Florian; Del Bene, Filippo

    2016-02-01

    Escape behaviors deliver organisms away from imminent catastrophe. Here, we characterize behavioral responses of freely swimming larval zebrafish to looming visual stimuli simulating predators. We report that the visual system alone can recruit lateralized, rapid escape motor programs, similar to those elicited by mechanosensory modalities. Two-photon calcium imaging of retino-recipient midbrain regions isolated the optic tectum as an important center processing looming stimuli, with ensemble activity encoding the critical image size determining escape latency. Furthermore, we describe activity in retinal ganglion cell terminals and superficial inhibitory interneurons in the tectum during looming and propose a model for how temporal dynamics in tectal periventricular neurons might arise from computations between these two fundamental constituents. Finally, laser ablations of hindbrain circuitry confirmed that visual and mechanosensory modalities share the same premotor output network. We establish a circuit for the processing of aversive stimuli in the context of an innate visual behavior. PMID:26804997

  2. Properties of the larval neuromuscular junction in Drosophila melanogaster.

    PubMed Central

    Jan, L Y; Jan, Y N

    1976-01-01

    The anatomy and physiology of the Drosophila larval neuromuscular junction were studied. 2. The dependence of muscle resting potentials on [K+]o and [Na+]o follows the Goldman-Hodgkin-Katz equation (PNa/PK=0-23). Chloride ions distribute passively across the membrane. 3. The mean specific membrane resistance of muscle fibres is 4-3 X 10(3) omega cm2, and the mean specific membrane capacitance is 7-1 muF/cm2. The muscle fibre is virtually isopotential. 4.Transmitter release is quantal. Both the miniature excitatory junctional potential and the evoked release follow the Poisson distribution. 5. Transmitter release depends on approximately the fourth power of [Ca2+]o. If Sr2+ replaces Ca2+, it depends on approximately the fourth power of [Sr2+]o. Mg2+ reduces transmitter release without altering the fourth power dependence on [Ca2+]o. Images A B A B Plate 3 PMID:11339

  3. Agreement among observers classifying larval sea lamprey (Petromyzon marinus) habitat

    USGS Publications Warehouse

    Mullett, K.M.; Bergstedt, R.A.

    2003-01-01

    Estimates of larval sea lamprey (Petromyzon marinus) abundance are used to rank Great Lakes tributaries for lampricide treatment. Observers subjectively stratify habitat into three categories: type I = preferred, type II = acceptable, type III = unacceptable. Agreement was evaluated among eight observers classifying habitats in small discrete plots in two Lake Superior tributaries, the Rock and Chocolay rivers, and among four observers classifying and measuring the amount of each habitat type along random transects in the Rock River. Agreement among the eight observers classifying habitat plots was high (Chocolay, ?? = 0.742 and Rock, ?? = 0.785). The amounts of types I, II, and III habitat estimated were statistically different among observers. However, the amount of variability found in the classification and measurement of habitat by observers had little effect on the ranking of 51 streams considered for lampricide treatment.

  4. The genus Odontophrynus (Anura: Odontophrynidae): a larval perspective.

    PubMed

    Filipe Augusto C, Do Nascimento; Tamí, Mott; José A, Langone; Christine A, Davis; Rafael O, De Sá

    2013-01-01

    The genus Odontophrynus consists of 11 species of medium-sized frogs distributed across south and east South America. This study examines and describes the chondrocrania and oral cavities of O. americanus, O. maisuma, O. carvalhoi, and O. cultripes, and review current knowledge about the larval external morphology of the genus. Twenty-one tadpoles were cleared and double-stained for chondrocranium description and five tadpoles were dissected for analysis in a scanning electron microscope. The presence of a tectum parientale may be considered here as a putative synapomorphy of the genus. The O. americanus and O. cultripes species groups were partially differentiated by the length of the processus pseudopterigoideus, shape of divergence of the hypobranchial plates, number of postnarial papillae, and number of projections of the lateral ridge papillae. The larvae of O. occidentalis species group, in turn, differed from others by presenting a greater total length. PMID:26106718

  5. Agreement among observers classifying larval sea lamprey (Petromyzon marinus) habitat

    USGS Publications Warehouse

    Mullett, Katherine M.; Bergstedt, Roger A.

    2003-01-01

    Estimates of larval sea lamprey (Petromyzon marinus) abundance are used to rank Great Lakes tributaries for lampricide treatment. Observers subjectively stratify habitat into three categories: type I = preferred, type II = acceptable, type III = unacceptable. Agreement was evaluated among eight observers classifying habitats in small discrete plots in two Lake Superior tributaries, the Rock and Chocolay rivers, and among four observers classifying and measuring the amount of each habitat type along random transects in the Rock River. Agreement among the eight observers classifying habitat plots was high (Chocolay, k = 0.742 and Rock, k = 0.785). The amounts of types I, II, and III habitat estimated were statistically different among observers. However, the amount of variability found in the classification and measurement of habitat by observers had little effect on the ranking of 51 streams considered for lampricide treatment.

  6. Environmentally relevant concentrations of microplastic particles influence larval fish ecology.

    PubMed

    Lönnstedt, Oona M; Eklöv, Peter

    2016-06-01

    The widespread occurrence and accumulation of plastic waste in the environment have become a growing global concern over the past decade. Although some marine organisms have been shown to ingest plastic, few studies have investigated the ecological effects of plastic waste on animals. Here we show that exposure to environmentally relevant concentrations of microplastic polystyrene particles (90 micrometers) inhibits hatching, decreases growth rates, and alters feeding preferences and innate behaviors of European perch (Perca fluviatilis) larvae. Furthermore, individuals exposed to microplastics do not respond to olfactory threat cues, which greatly increases predator-induced mortality rates. Our results demonstrate that microplastic particles operate both chemically and physically on larval fish performance and development. PMID:27257256

  7. Feeding competition between larval lake whitefish and lake herring

    USGS Publications Warehouse

    Savino, Jacqueline F.; Hudson, Patrick L.

    1995-01-01

    The potential for competition for food between larval lake whitefish (Coregonus clupeaformis) and lake herring (C. artedi) 1- to 8-wk of age was explored in a series of 1-h laboratory feeding studies. Feeding started at 2-wk post-hatch. Learning and fish size appear to be more important than prey density at the onset of feeding. Species differed in their feeding behavior and consumption noticeably by 5-wk and substantially by 8-wk. Lake whitefish generally were more aggressive foragers than lake herring, attacking and capturing more prey. At high plankton density at 8-wk, lake herring feeding was depressed in mixed-fish treatments. This difference in competitive food consumption between the two coregonids occurs at a critical life stage, and when combined with other biotic and abiotic factors, may have a significant impact on recruitment.

  8. Embryonic and larval development of Brycon amazonicus (SPIX & AGASSIZ, 1829).

    PubMed

    Nakauth, A C S Sampaio; Villacorta-Correa, M A; Figueiredo, M R; Bernardino, G; França, J M

    2016-02-01

    The objective of this study was to describe the embryonic and larval development of Brycon amazonicus, featuring the main events up to 50 hours after fertilization (AF). The material was provided by the Aquaculture Training, Technology and Production Center, Presidente Figueiredo (AM). The characterization was based on stereomicroscopic examination of the morphology of eggs, embryos and larvae and comparison with the literature. Matrinxã eggs are free, transparent, and spherical, with a perivitelline space of 0.56 ± 0.3 mm. The successive divisions give rise to cells with 64 blastomeres during the first hour AF. The gastrula stage, beginning 02 h 40 min AF, was characterized by progressive regression cells and the formation of the embryonic axis, leading to differentiation of the head and tail 05 h 30 min AF. From 06 to 09 h AF the somites, notochord, otic and optic vesicles and otoliths were observed, in addition to heart rate and the release of the tail. The larvae hatched at 10 h 30 min AF (29.9 °C), with a total length of 3.56 ± 0.46 mm. Between 19 and 30 h AF, we observed 1) pigmentation and gut formation, 2) branchial arches, 3) pectoral fins, 4) a mouth opening and 5) teeth. Cannibalism was initiated earlier (34 h AF) which was associated with rapid yolk absorption (more than 90% until 50 h AF), signaling the need for an exogenous nutritional source. The environmental conditions (especially temperature) influenced the time course of some events throughout the embryonic and larval development, suggesting the need for further studies on this subject. PMID:26909629

  9. Biased gene expression in early honeybee larval development

    PubMed Central

    2013-01-01

    Background Female larvae of the honeybee (Apis mellifera) develop into either queens or workers depending on nutrition. This nutritional stimulus triggers different developmental trajectories, resulting in adults that differ from each other in physiology, behaviour and life span. Results To understand how these trajectories are established we have generated a comprehensive atlas of gene expression throughout larval development. We found substantial differences in gene expression between worker and queen-destined larvae at 6 hours after hatching. Some of these early changes in gene expression are maintained throughout larval development, indicating that caste-specific developmental trajectories are established much earlier than previously thought. Within our gene expression data we identified processes that potentially underlie caste differentiation. Queen-destined larvae have higher expression of genes involved in transcription, translation and protein folding early in development with a later switch to genes involved in energy generation. Using RNA interference, we were able to demonstrate that one of these genes, hexamerin 70b, has a role in caste differentiation. Both queen and worker developmental trajectories are associated with the expression of genes that have alternative splice variants, although only a single variant of a gene tends to be differentially expressed in a given caste. Conclusions Our data, based on the biases in gene expression early in development together with published data, supports the idea that caste development in the honeybee consists of two phases; an initial biased phase of development, where larvae can still switch to the other caste by differential feeding, followed by commitment to a particular developmental trajectory. PMID:24350621

  10. Influence of Physiological Stress on Nutrient Stoichiometry in Larval Amphibians.

    PubMed

    Kirschman, Lucas J; Haslett, Savhannah; Fritz, Kelley A; Whiles, Matt R; Warne, Robin W

    2016-01-01

    Exposure to environmental stressors alters animal phenotypes as well as nutrient metabolism, assimilation, and excretion. While stress-induced shifts in nutrient processes are known to alter organismal carbon (C) and nitrogen (N) stoichiometry, there has been little exploration of how environmental factors influence phosphorous (P). A better understanding of how P cycling varies with animal physiological state may provide insight into across-scale processes, because P is essential to animal function and ecological processes such as production and decomposition. We tested the effects of predator stress and exogenous glucocorticoids on C∶N∶P stoichiometry of larval amphibians. Glucocorticoids altered nutrient stoichiometry, apparently by modulating ossification and renal function. This reduced whole-body P and significantly increased N∶P. Additionally, elevated glucocorticoids caused a long-term reduction in P excretion. This reduction may reflect an initial unmeasured loss of P that glucocorticoids induce over acute timescales. In contrast, exposure to predator cues had no effect on larval C∶N∶P stoichiometry, which highlights that different stressors have varied effects on the endocrine stress response. Predation, in particular, is ubiquitous in the environment; thus, larvae responding to predators have conserved mechanisms that likely prevent or minimize physiological disruption. These results demonstrate the differing physiological roles of N and P, distinct nutrient demands associated with amphibian metamorphosis, and the contrasting effects that different environmental factors have on the physiological stress response. Our results also suggest that anthropogenic changes to the environment that induce chronic stress in amphibians could affect the biogeochemistry of nutrient-poor environments where they may act as keystone species. PMID:27327181

  11. Spatial dynamics of large-scale, multistage crab (Callinectes sapidus) dispersal: Determinants and consequences for recruitment

    USGS Publications Warehouse

    Etherington, L.L.; Eggleston, D.B.

    2003-01-01

    We assessed determinants and consequences of multistage dispersal on spatial recruitment of the blue crab, Callinectes sapidus, within the Croatan, Albemarle, Pamlico Estuarine System (CAPES), North Carolina, U.S.A. Large-scale sampling of early juvenile crabs over 4 years indicated that spatial abundance patterns were size-dependent and resulted from primary post-larval dispersal (pre-settlement) and secondary juvenile dispersal (early post-settlement). In general, primary dispersal led to high abundances within more seaward habitats, whereas secondary dispersal (which was relatively consistent) expanded the distribution of juveniles, potentially increasing the estuarine nursery capacity. There were strong relationships between juvenile crab density and specific wind characteristics; however, these patterns were spatially explicit. Various physical processes (e.g., seasonal wind events, timing and magnitude of tropical cyclones) interacted to influence dispersal during multiple stages and determined crab recruitment patterns. Our results suggest that the nursery value of different habitats is highly dependent on the dispersal potential (primary and secondary dispersal) to and from these areas, which is largely determined by the relative position of habitats within the estuarine landscape.

  12. Structural habitat predicts functional dispersal habitat of a large carnivore: how leopards change spots.

    PubMed

    Fattebert, Julien; Robinson, Hugh S; Balme, Guy; Slotow, Rob; Hunter, Luke

    2015-10-01

    Natal dispersal promotes inter-population linkage, and is key to spatial distribution of populations. Degradation of suitable landscape structures beyond the specific threshold of an individual's ability to disperse can therefore lead to disruption of functional landscape connectivity and impact metapopulation function. Because it ignores behavioral responses of individuals, structural connectivity is easier to assess than functional connectivity and is often used as a surrogate for landscape connectivity modeling. However using structural resource selection models as surrogate for modeling functional connectivity through dispersal could be erroneous. We tested how well a second-order resource selection function (RSF) models (structural connectivity), based on GPS telemetry data from resident adult leopard (Panthera pardus L.), could predict subadult habitat use during dispersal (functional connectivity). We created eight non-exclusive subsets of the subadult data based on differing definitions of dispersal to assess the predictive ability of our adult-based RSF model extrapolated over a broader landscape. Dispersing leopards used habitats in accordance with adult selection patterns, regardless of the definition of dispersal considered. We demonstrate that, for a wide-ranging apex carnivore, functional connectivity through natal dispersal corresponds to structural connectivity as modeled by a second-order RSF. Mapping of the adult-based habitat classes provides direct visualization of the potential linkages between populations, without the need to model paths between a priori starting and destination points. The use of such landscape scale RSFs may provide insight into predicting suitable dispersal habitat peninsulas in human-dominated landscapes where mitigation of human-wildlife conflict should be focused. We recommend the use of second-order RSFs for landscape conservation planning and propose a similar approach to the conservation of other wide-ranging large

  13. Plasticity of larval pre-competency in response to temperature: observations on multiple broadcast spawning coral species

    NASA Astrophysics Data System (ADS)

    Heyward, A. J.; Negri, A. P.

    2010-09-01

    The pre-competency period of coral larvae influences dispersal, and this may be affected under projected climate change conditions. In this laboratory study, we examined the influence of sea water temperature on the duration of pre-competency of larvae of four broadcast spawning coral species. Fungia repanda, Acropora millepora, A. spathulata and Symphyllia recta larvae demonstrated large differences in cohort competency levels when cultured over a 4°C range during the first 4 days post fertilisation. Warmer temperatures reduced pre-competency periods by at least a day for all species, but there were also indications of an upper temperature threshold of less than 32°C for the development of F. repanda, A. millepora and S. recta. These data suggest a general flexibility in ontogenic response to ambient water temperatures. Sea surface temperatures (SST) that differ at spawning time by as little as 2°C, due to inter-annual or latitudinal variation, are likely to alter coral larval dispersal ranges. In some locations, notably the central Indo-Pacific, where major coral spawning activity can coincide with seasonal SST maxima, a future 2°C increase due to climate change may have serious negative effects on coral development and distribution.

  14. Cauchy's dispersion equation reconsidered : dispersion in silicate glasses.

    SciTech Connect

    Smith, D. Y.; Inokuti, M.; Karstens, W.; Physics; Univ. of Vermont; St. Michael's College

    2002-01-01

    We formulate a novel method of characterizing optically transparent substances using dispersion theory. The refractive index is given by a generalized Cauchy dispersion equation with coefficients that are moments of the uv and ir absorptions. Mean dispersion, Abbe number, and partial dispersion are combinations of these moments. The empirical relation between index and dispersion for families of glasses appears as a consequence of Beer's law applied to the uv spectra.

  15. KISMET tungsten dispersal experiment

    SciTech Connect

    Wohletz, K.; Kunkle, T.; Hawkins, W.

    1996-12-01

    Results of the KISMET tungsten dispersal experiment indicate a relatively small degree of wall-rock contamination caused by this underground explosive experiment. Designed as an add-on to the KISMET test, which was performed in the U-1a.02 drift of the LYNER facility at Nevada Test Site on 1 March 1995, this experiment involved recovery and analysis of wall-rock samples affected by the high- explosive test. The chemical, high-explosive blast drove tungsten powder, placed around the test package as a plutonium analog, into the surrounding wall- rock alluvium. Sample analyses by an analytical digital electron microscope (ADEM) show tungsten dispersed in the rock as tiny (<10 {mu}m) particles, agglomerates, and coatings on alluvial clasts. Tungsten concentrations, measured by energy dispersive spectral analysis on the ADEM, indicate penetration depths less than 0.1 m and maximum concentrations of 1.5 wt % in the alluvium.

  16. Fog dispersal technology.

    NASA Technical Reports Server (NTRS)

    Mcgowan, W. A.

    1971-01-01

    The state-of-the-art in fog dispersal technology is briefly discussed. Fog is categorized as supercooled fog, occurring in air temperatures below freezing, and warm fog, occurring at above-freezing temperatures. Operational techniques are available to disperse supercooled fog in the airport area. It is much more difficult to cope with warm fog. Various known concepts to disperse warm fog are evaluated as to their operational merits. The most effective concept for immediate use involves heating the air to cause fog evaporation. Use of helicopter downwash has some application, possibly complementing the promising concept of seeding with sized hygroscopic particles. These latter two concepts appear to have future application, pending further research. The concept using polyelectrolytes is of uncertain value, lacking both a scientific explanation and a substantive evaluation of reported operational successes.

  17. Drilling mud dispersants

    SciTech Connect

    Gleason, P. A.; Brase, I. E.

    1985-05-21

    Dispersants useful in aqueous drilling mud formulations employed in the drilling of subterranean wells where high temperature and high pressure environments are encountered are disclosed. The dispersants, when used in amounts of about 0.1 to 25 ppb provide muds containing colloidal material suspended in an aqueous medium with improved high temperature and high pressure stability. The dispersants are water soluble sulfonated vinyl toluene-maleic anhydride copolymers which have a molar ratio of vinyl toluene to maleic anhydride of about 1:1 to less than about 2:1, a molecular weight of 1,000 to 25,000 and at least about 0.7 sulfonic acid groups per vinyl toluene unit.

  18. Larval development of Culex quinquefasciatus in water with low to moderate.

    PubMed

    Noori, Navideh; Lockaby, B Graeme; Kalin, Latif

    2015-12-01

    Population growth and urbanization have increased the potential habitats, and consequently the abundance of Culex quinquefasciatus, the southern house mosquito, a vector of West Nile Virus in urban areas. Water quality is critical in larval habitat distribution and in providing microbial food resources for larvae. A mesocosm experiment was designed to demonstrate which specific components of water chemistry are conducive to larval Culex mosquitoes. Dose-response relationships between larval development and NO3 , NH4 , and PO4 concentrations in stream water were developed through this experiment to describe the isolated effects of each nutrient on pre-adult development. The emergence pattern of Culex mosquitoes was found to be strongly related to certain nutrients, and results showed that breeding sites with higher PO4 or NO3 concentrations had higher larval survival rates. High NO3 concentrations favor the development of male mosquitoes and suppress the development of female mosquitoes, but those adult females that do emerge develop faster in containers with high NO3 levels compared to the reference group. The addition of PO4 in the absence of nitrogen sources to the larval habitat slowed larval development, however, it took fewer days for larvae to reach the pupal stage in containers with combinations of NO3 and PO4 or NH4 and PO4 nutrients. Results from this study may bolster efforts to control WNV in urban landscapes by exploring water quality conditions of Culex larval habitats that produce adult mosquitoes. PMID:26611953

  19. Cyanobacteria associated with Anopheles albimanus (Diptera: Culicidae) larval habitats in southern Mexico.

    PubMed

    Vázquez-Martínez, M Guadalupe; Rodríguez, Mario H; Arredondo-Jiménez, Juan I; Méndez-Sanchez, José D; Bond-Compeán, J Guillermo; Cold-Morgan, Michelle

    2002-11-01

    Cyanobacteria associated with Anopheles albimanus Wiedemann larval habitats from southern Chiapas, Mexico, were isolated and identified from water samples and larval midguts using selective medium BG-11. Larval breeding sites were classified according to their hydrology and dominant vegetation. Cyanobacteria isolated in water samples were recorded and analyzed according to hydrological and vegetation habitat breeding types, and mosquito larval abundance. In total, 19 cyanobacteria species were isolated from water samples. Overall, the most frequently isolated cyanobacterial taxa were Phormidium sp., Oscillatoria sp., Aphanocapsa cf. littoralis, Lyngbya lutea, P. animalis, and Anabaena cf. spiroides. Cyanobacteria were especially abundant in estuaries, irrigation canals, river margins and mangrove lagoons, and more cyanobacteria were isolated from Brachiaria mutica, Ceratophyllum demersum, and Hymenachne amplexicaulis habitats. Cyanobacteria were found in habitats with low to high An. albimanus larval abundance, but Aphanocapsa cf. littoralis was associated with habitats of low larval abundance. No correlation was found between water chemistry parameters and the presence of cyanobacteria, however, water temperature (29.2-29.4 degrees C) and phosphate concentration (79.8-136.5 ppb) were associated with medium and high mosquito larvae abundance. In An. albimanus larval midguts, only six species of cyanobacteria were isolated, the majority being from the most abundant cyanobacteria in water samples. PMID:12495179

  20. Effects of larval density in Ambystoma opacum: An experiment in large-scale field enclosures

    SciTech Connect

    Scott, D.E. )

    1990-02-01

    This experiment was designed to measure the effects of larval density on larval traits in the salamander Ambystoma opacum, and to ascertain whether previous studies conducted at smaller spatial scales or higher densities produced artifactual results. Density effects on larval growth, body size at metamorphosis, length of larval period, and survival to metamorphosis were studied in A. opacum in large-scale (41 m{sup 2} and 23 m{sup 2}) field enclosures in two temporary ponds. Each enclosure contained indigenous populations of prey (zooplankton and insects) and predators, as well as the range of microhabitats present in these natural ponds. Initial larval densities were chosen to represent high and low levels of naturally occurring mean densities. The results suggest that, in natural ponds, the importance of intraspecific competition is dependent upon hydroperiod, and the intensity of competition influences predation risk. Thus, both density-dependent and density-independent factors affect body size and recruitment of larval A. opacum into the adult population. The use of large-scale field enclosures has advantages and disadvantages: it allows the examination of density-dependent processes under natural conditions and provides high statistical power because of low variability in larval traits; however, experimental designs must be simple and underlying mechanisms are difficult to identify.

  1. Multiscale analysis of compartment models with dispersal

    PubMed Central

    Kang, Yun; Castillo-Chavez, Carlos

    2014-01-01

    Dispersal, minimally defined as the movement or spatial displacement of organisms, links the dynamics of local population within and across regions. Landscape-population interactions responsible for driving co-evolutionary processes that on the long run shape communities of organisms, determine the outcomes of biological invasions, or alter the dynamics and evolution of infectious agents, are connected via dispersal. A generalized modeling framework is introduced derived from our interests in characterizing the dynamics of animal populations and trade in the presence of disease. We explore the impact of dispersal on systems that include disease, Allee effects, and host mobility. The emphasis is on disease, a selective force, that often plays a fundamental role on the life-history dynamics of a population. The models incorporate disease-driven effects on, often excluded, interactions like individual’s competitive ability to acquire resources. The framework makes use of deterministic and stochastic models that account for features often ignored or rarely included like (a) induced Allee effects; (b) disease dynamics; and (c) spatial heterogeneity. Preliminary results highlight the role of initial conditions, patch quality, and “topological” or connectivity landscape structure (the physical space where individuals move, reproduce, get sick, die, or compete for resources) on the dynamics of populations when disease is an important selective force. We dedicate this article to our grand mentor Simon Levin. PMID:22934939

  2. About measuring velocity dispersions

    NASA Astrophysics Data System (ADS)

    Fellhauer, M.

    A lot of our knowledge about the dynamics and total masses of pressure dominated stellar systems relies on measuring the internal velocity disper- sion of the system. We assume virial equilibrium and that we are able to measure only the bound stars of the system without any contamination. This article shows how likely it is to measure the correct velocity dispersion in reality. It will show that as long as we have small samples of velocity mea- surements the distribution of possible outcomes can be very large and as soon as we have a source of error the velocity dispersion can wrong by several standard deviations especially in large samples.

  3. Uranium Dispersion & Dosimetry Model.

    SciTech Connect

    MICHAEL,; MOMENI, H.

    2002-03-22

    The Uranium Dispersion and Dosimetry (UDAD) program provides estimates of potential radiation exposure to individuals and to the general population in the vicinity of a uranium processing facility such as a uranium mine or mill. Only transport through the air is considered. Exposure results from inhalation, external irradiation from airborne and ground-deposited activity, and ingestion of foodstuffs. Individual dose commitments, population dose commitments, and environmental dose commitments are computed. The program was developed for application to uranium mining and milling; however, it may be applied to dispersion of any other pollutant.

  4. Uranium Dispersion & Dosimetry Model.

    Energy Science and Technology Software Center (ESTSC)

    2002-03-22

    The Uranium Dispersion and Dosimetry (UDAD) program provides estimates of potential radiation exposure to individuals and to the general population in the vicinity of a uranium processing facility such as a uranium mine or mill. Only transport through the air is considered. Exposure results from inhalation, external irradiation from airborne and ground-deposited activity, and ingestion of foodstuffs. Individual dose commitments, population dose commitments, and environmental dose commitments are computed. The program was developed for applicationmore » to uranium mining and milling; however, it may be applied to dispersion of any other pollutant.« less

  5. Pollen clumping and wind dispersal in an invasive angiosperm.

    PubMed

    Martin, Michael D; Chamecki, Marcelo; Brush, Grace S; Meneveau, Charles; Parlange, Marc B

    2009-09-01

    Pollen dispersal is a fundamental aspect of plant reproductive biology that maintains connectivity between spatially separated populations. Pollen clumping, a characteristic feature of insect-pollinated plants, is generally assumed to be a detriment to wind pollination because clumps disperse shorter distances than do solitary pollen grains. Yet pollen clumps have been observed in dispersion studies of some widely distributed wind-pollinated species. We used Ambrosia artemisiifolia (common ragweed; Asteraceae), a successful invasive angiosperm, to investigate the effect of clumping on wind dispersal of pollen under natural conditions in a large field. Results of simultaneous measurements of clump size both in pollen shedding from male flowers and airborne pollen being dispersed in the atmosphere are combined with a transport model to show that rather than being detrimental, clumps may actually be advantageous for wind pollination. Initial clumps can pollinate the parent population, while smaller clumps that arise from breakup of larger clumps can cross-pollinate distant populations. PMID:21622356

  6. Larval intraspecific competition for food in the European grapevine moth Lobesia botrana.

    PubMed

    Thiéry, D; Monceau, K; Moreau, J

    2014-08-01

    Effective pest management with lower amounts of pesticides relies on accurate prediction of insect pest growth rates. Knowledge of the factors governing this trait and the resulting fitness of individuals is thus necessary to refine predictions and make suitable decisions in crop protection. The European grapevine moth, Lobesia botrana, the major pest of grapes in Europe, is responsible for huge economic losses. Larvae very rarely leave the grape bunch on which they were oviposited and thus cannot avoid intraspecific competition. In this study, we determined the impact of intraspecific competition during the larval stage on development and adult fitness in this species. This was tested by rearing different numbers of larvae on an artificial diet and measuring developmental and reproductive life history traits. We found that intraspecific competition during larval development has a slight impact on the fitness of L. botrana. The principal finding of this work is that larval density has little effect on the life history traits of survivors. Thus, the timing of eclosion, duration of subsequent oviposition, fecundity appears to be more uniform in L. botrana than in other species. The main effect of larval crowding was a strong increase of larval mortality at high densities whereas the probability of emergence, sex ratio, pupal mass, fecundity and longevity of mated females were not affected by larval crowding. Owing to increased larval mortality at high larval densities, we hypothesized that mortality of larvae at high densities provided better access to food for the survivors with the result that more food was available per capita and there were no effect on fitness of survivors. From our results, larval crowding alters the reproductive capacity of this pest less than expected but this single factor should now be tested in interaction with limited resources in the wild. PMID:24788023

  7. Optimizing larval assessment to support sea lamprey control in the Great Lakes

    USGS Publications Warehouse

    Hansen, Michael J.; Adams, Jean V.; Cuddy, Douglas W.; Richards, Jessica M.; Fodale, Michael F.; Larson, Geraldine L.; Ollila, Dale J.; Slade, Jeffrey W.; Steeves, Todd B.; Young, Robert J.; Zerrenner, Adam

    2003-01-01

    Elements of the larval sea lamprey (Petromyzon marinus) assessment program that most strongly influence the chemical treatment program were analyzed, including selection of streams for larval surveys, allocation of sampling effort among stream reaches, allocation of sampling effort among habitat types, estimation of daily growth rates, and estimation of metamorphosis rates, to determine how uncertainty in each element influenced the stream selection program. First, the stream selection model based on current larval assessment sampling protocol significantly underestimated transforming sea lam-prey abundance, transforming sea lampreys killed, and marginal costs per sea lamprey killed, compared to a protocol that included more years of data (especially for large streams). Second, larval density in streams varied significantly with Type-I habitat area, but not with total area or reach length. Third, the ratio of larval density between Type-I and Type-II habitat varied significantly among streams, and that the optimal allocation of sampling effort varied with the proportion of habitat types and variability of larval density within each habitat. Fourth, mean length varied significantly among streams and years. Last, size at metamorphosis varied more among years than within or among regions and that metamorphosis varied significantly among streams within regions. Study results indicate that: (1) the stream selection model should be used to identify streams with potentially high residual populations of larval sea lampreys; (2) larval sampling in Type-II habitat should be initiated in all streams by increasing sampling in Type-II habitat to 50% of the sampling effort in Type-I habitat; and (3) methods should be investigated to reduce uncertainty in estimates of sea lamprey production, with emphasis on those that reduce the uncertainty associated with larval length at the end of the growing season and those used to predict metamorphosis.

  8. Differences in Time until Dispersal between Cryptic Species of a Marine Nematode Species Complex

    PubMed Central

    De Meester, Nele; Derycke, Sofie; Moens, Tom

    2012-01-01

    Co-occurrence of closely related species may be achieved in environments with fluctuating dynamics, where competitively inferior species can avoid competition through dispersal. Here we present an experiment in which we compared active dispersal abilities (time until first dispersal, number and gender of dispersive adults, and nematode densities at time of dispersal) in Litoditis marina, a common bacterivorous nematode species complex comprising four often co-occurring cryptic species, Pm I, II, III, and IV, as a function of salinity and food distribution. The experiment was conducted in microcosms consisting of an inoculation plate, connection tube, and dispersal plate. Results show species-specific dispersal abilities with Pm I dispersing almost one week later than Pm III. The number of dispersive adults at time of first dispersal was species-specific, with one dispersive female in Pm I and Pm III and a higher, gender-balanced, number in Pm II and Pm IV. Food distribution affected dispersal: in absence of food in the inoculation plate, all species dispersed after ca four days. When food was available Pm I dispersed later, and at the same time and densities irrespective of food conditions in the dispersal plate (food vs no food), suggesting density-dependent dispersal. Pm III dispersed faster and at a lower population density. Salinity affected dispersal, with slower dispersal at higher salinity. These results suggest that active dispersal in Litoditis marina is common, density-dependent, and with species, gender- and environment-specific dispersal abilities. These differences can lead to differential responses under suboptimal conditions and may help to explain temporary coexistence at local scales. PMID:22876328

  9. Testing comparative phylogeographic models of marine vicariance and dispersal using a hierarchical Bayesian approach

    PubMed Central

    2008-01-01

    Background Marine allopatric speciation is an enigma because pelagic larval dispersal can potentially connect disjunct populations thereby preventing reproductive and morphological divergence. Here we present a new hierarchical approximate Bayesian computation model (HABC) that tests two hypotheses of marine allopatric speciation: 1.) "soft vicariance", where a speciation involves fragmentation of a large widespread ancestral species range that was previously connected by long distance gene flow; and 2.) peripatric colonization, where speciations in peripheral archipelagos emerge from sweepstakes colonizations from central source regions. The HABC approach analyzes all the phylogeographic datasets at once in order to make across taxon-pair inferences about biogeographic processes while explicitly allowing for uncertainty in the demographic differences within each taxon-pair. Our method uses comparative phylogeographic data that consists of single locus mtDNA sequences from multiple co-distributed taxa containing pairs of central and peripheral populations. We use the method on two comparative phylogeographic data sets consisting of cowrie gastropod endemics co-distributed in the Hawaiian (11 taxon-pairs) and Marquesan archipelagos (7 taxon-pairs). Results Given the Marquesan data, we find strong evidence of simultaneous colonization across all seven cowrie gastropod endemics co-distributed in the Marquesas. In contrast, the lower sample sizes in the Hawaiian data lead to greater uncertainty associated with the Hawaiian estimates. Although, the hyper-parameter estimates point to soft vicariance in a subset of the 11 Hawaiian taxon-pairs, the hyper-prior and hyper-posterior are too similar to make a definitive conclusion. Both results are not inconsistent with what is known about the geologic history of the archipelagos. Simulations verify that our method can successfully distinguish these two histories across a wide range of conditions given sufficient sampling

  10. Warm fog dispersal

    NASA Technical Reports Server (NTRS)

    Frost, W.

    1983-01-01

    The charged particle generator was further tested after some design modification. The generator performance was measured with additional instrumentation and found to confirm previous measurements. Plans for a field testing were than developed. The overall status of the program and the field test plans were presented to a group of atmospheric scientists and electrostatic experts at the NASA/MSFC sponsored USRA Workshop on Electrostatic Fog Dispersal at NCAR, Boulder, Colorado discussed in previous sections. The recommendations from this workshop are being evaluated as to whether NASA should proceed with the field test or whether further theoretical research on the phenomenon of electrostatic fog dispersal and additional development of the charged particle generator should be carried out. Information obtained from the USRA Workshop clearly identified three physical mechanisms that could possibly influence the fog dispersal process, which heretofore have not been considered, and which may provide additional insight to the direction of further fog dispersal work. These mechanisms are: the effect of corona discharge on the electric field strength at the surface, the influx of fog into the cleared volume by turbulent diffusion, and the increase in supersaturation as liquid water is removed, activating haze particles, and thus generating more fog. Plans are being formulated to investigate these mechanisms.

  11. Acoustic dispersive prism.

    PubMed

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  12. Acoustic dispersive prism

    PubMed Central

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz–1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  13. Acoustic dispersive prism

    NASA Astrophysics Data System (ADS)

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium.

  14. Uncovering the connectivity of coral reef systems via Lagrangian Coherent Structures

    NASA Astrophysics Data System (ADS)

    Leclair, Matthieu; Lowe, Ryan; Zang, Zhenlin; Ivey, Gregory; Peacock, Thomas

    2015-04-01

    There has been a staggering decline in the health of coral reef ecosystems worldwide over the past century, driven by anthropogenic influences, natural processes, and overall climate change. The future of coral reefs depends largely on their ability to recover from catastrophic events, which in turn crucially relies on the ability of reef larval populations to supply and restore damaged reefs. Improving quantitative predictions of reef larval transport and connectivity has thus emerged as a high priority research area in coral reef science. Ocean circulation models are being increasingly utilized in conjunction with particle tracking methods to provide spatially explicit predictions of larval transport within reef systems. The current major drawback of this approach is that it does not elucidate the underlying yet dynamic flow structures that drive reef connectivity. Recently, however, novel Lagrangian-based analysis approaches have been developed to identify the hidden coherent structures that govern material transport in spatiotemporally complex flow fields. Here we apply these methods to investigate the connectivity within a complex coral reef system, using the UNESCO World Heritage Ningaloo Reef in Australia as a case study. Our study demonstrates how this new approach identifies the dominant flow structures present on the reef, thereby uncovering connectivity and advocating a new practical framework for investigating and understanding how ocean processes shape the ecological transport in and around coral reefs. The technique can prove particularly valuable in supporting the design of Marine Protected Areas that are intended to safeguard the future of coral reefs and other ocean ecosystems.

  15. Octave spanning wedge dispersive mirrors with low dispersion oscillations.

    PubMed

    Habel, Florian; Shirvanyan, Vage; Trubetskov, Michael; Burger, Christian; Sommer, Annkatrin; Kling, Matthias F; Schultze, Martin; Pervak, Vladimir

    2016-05-01

    A novel concept for octave spanning dispersive mirrors with low spectral dispersion oscillations is presented. The key element of the so-called wedge dispersive mirror is a slightly wedged layer which is coated on a specially optimized dispersive multilayer stack by a common sputter coating process. The group delay dispersion (GDD) of a pulse reflected on a wedge dispersive mirror is nearly free of oscillations. Fabricated mirrors with negative GDD demonstrate the compression of a pulse down to 3.8 fs as good as double angled mirrors optimized for the same bandwidth. PMID:27137538

  16. Dispersal similarly shapes both population genetics and community patterns in the marine realm

    PubMed Central

    Chust, Guillem; Villarino, Ernesto; Chenuil, Anne; Irigoien, Xabier; Bizsel, Nihayet; Bode, Antonio; Broms, Cecilie; Claus, Simon; Fernández de Puelles, María L.; Fonda-Umani, Serena; Hoarau, Galice; Mazzocchi, Maria G.; Mozetič, Patricija; Vandepitte, Leen; Veríssimo, Helena; Zervoudaki, Soultana; Borja, Angel

    2016-01-01

    Dispersal plays a key role to connect populations and, if limited, is one of the main processes to maintain and generate regional biodiversity. According to neutral theories of molecular evolution and biodiversity, dispersal limitation of propagules and population stochasticity are integral to shaping both genetic and community structure. We conducted a parallel analysis of biological connectivity at genetic and community levels in marine groups with different dispersal traits. We compiled large data sets of population genetic structure (98 benthic macroinvertebrate and 35 planktonic species) and biogeographic data (2193 benthic macroinvertebrate and 734 planktonic species). We estimated dispersal distances from population genetic data (i.e., FST vs. geographic distance) and from β-diversity at the community level. Dispersal distances ranked the biological groups in the same order at both genetic and community levels, as predicted by organism dispersal ability and seascape connectivity: macrozoobenthic species without dispersing larvae, followed by macrozoobenthic species with dispersing larvae and plankton (phyto- and zooplankton). This ranking order is associated with constraints to the movement of macrozoobenthos within the seabed compared with the pelagic habitat. We showed that dispersal limitation similarly determines the connectivity degree of communities and populations, supporting the predictions of neutral theories in marine biodiversity patterns. PMID:27344967

  17. Dispersal similarly shapes both population genetics and community patterns in the marine realm.

    PubMed

    Chust, Guillem; Villarino, Ernesto; Chenuil, Anne; Irigoien, Xabier; Bizsel, Nihayet; Bode, Antonio; Broms, Cecilie; Claus, Simon; Fernández de Puelles, María L; Fonda-Umani, Serena; Hoarau, Galice; Mazzocchi, Maria G; Mozetič, Patricija; Vandepitte, Leen; Veríssimo, Helena; Zervoudaki, Soultana; Borja, Angel

    2016-01-01

    Dispersal plays a key role to connect populations and, if limited, is one of the main processes to maintain and generate regional biodiversity. According to neutral theories of molecular evolution and biodiversity, dispersal limitation of propagules and population stochasticity are integral to shaping both genetic and community structure. We conducted a parallel analysis of biological connectivity at genetic and community levels in marine groups with different dispersal traits. We compiled large data sets of population genetic structure (98 benthic macroinvertebrate and 35 planktonic species) and biogeographic data (2193 benthic macroinvertebrate and 734 planktonic species). We estimated dispersal distances from population genetic data (i.e., FST vs. geographic distance) and from β-diversity at the community level. Dispersal distances ranked the biological groups in the same order at both genetic and community levels, as predicted by organism dispersal ability and seascape connectivity: macrozoobenthic species without dispersing larvae, followed by macrozoobenthic species with dispersing larvae and plankton (phyto- and zooplankton). This ranking order is associated with constraints to the movement of macrozoobenthos within the seabed compared with the pelagic habitat. We showed that dispersal limitation similarly determines the connectivity degree of communities and populations, supporting the predictions of neutral theories in marine biodiversity patterns. PMID:27344967

  18. Traffic congestion and dispersion in Hurricane evacuation

    NASA Astrophysics Data System (ADS)

    Tanaka, Katsunori; Nagatani, Takashi; Hanaura, Hirotoshi

    2007-03-01

    We study the traffic congestion and dispersion of vehicles occurring on a single lane highway in Hurricane evacuation. The traffic congestion depends on both sensitivity and speed of the leading vehicle. When the leading vehicle moves with low speed, the vehicular traffic exhibits the stop and go-wave (oscillating congested traffic) for low sensitivity, while the traffic results in the homogeneous congested traffic for high sensitivity. The traffic dispersion is measured by the time difference between the leading and rear vehicles. The time difference fluctuates highly for the oscillating congestion traffic, while it keeps a constant value for the homogeneous congested traffic. The traffic states in Hurricane evacuation is connected to the phase diagram of conventional traffic.

  19. Dispersion-free radial transmission lines

    DOEpatents

    Caporaso, George J.; Nelson, Scott D.

    2011-04-12

    A dispersion-free radial transmission line ("DFRTL") preferably for linear accelerators, having two plane conductors each with a central hole, and an electromagnetically permeable material ("EPM") between the two conductors and surrounding a channel connecting the two holes. At least one of the material parameters of relative magnetic permeability, relative dielectric permittivity, and axial width of the EPM is varied as a function of radius, so that the characteristic impedance of the DFRTL is held substantially constant, and pulse transmission therethrough is substantially dispersion-free. Preferably, the EPM is divided into concentric radial sections, with the varied material parameters held constant in each respective section but stepwise varied between sections as a step function of the radius. The radial widths of the concentric sections are selected so that pulse traversal time across each section is the same, and the varied material parameters of the concentric sections are selected to minimize traversal error.

  20. A capture-recapture model of amphidromous fish dispersal.

    PubMed

    Smith, W E; Kwak, T J

    2014-04-01

    Adult movement scale was quantified for two tropical Caribbean diadromous fishes, bigmouth sleeper Gobiomorus dormitor and mountain mullet Agonostomus monticola, using passive integrated transponders (PITs) and radio-telemetry. Large numbers of fishes were tagged in Río Mameyes, Puerto Rico, U.S.A., with PITs and monitored at three fixed locations over a 2·5 year period to estimate transition probabilities between upper and lower elevations and survival probabilities with a multistate Cormack-Jolly-Seber model. A sub-set of fishes were tagged with radio-transmitters and tracked at weekly intervals to estimate fine-scale dispersal. Changes in spatial and temporal distributions of tagged fishes indicated that neither G. dormitor nor A. monticola moved into the lowest, estuarine reaches of Río Mameyes during two consecutive reproductive periods, thus demonstrating that both species follow an amphidromous, rather than catadromous, migratory strategy. Further, both species were relatively sedentary, with restricted linear ranges. While substantial dispersal of these species occurs at the larval stage during recruitment to fresh water, the results indicate minimal dispersal in spawning adults. Successful conservation of diadromous fauna on tropical islands requires management at both broad basin and localized spatial scales. PMID:24673127

  1. A capture-recapture model of amphidromous fish dispersal

    USGS Publications Warehouse

    Smith, W.; Kwak, Thomas J.

    2014-01-01

    Adult movement scale was quantified for two tropical Caribbean diadromous fishes, bigmouth sleeper Gobiomorus dormitor and mountain mullet Agonostomus monticola, using passive integrated transponders (PITs) and radio-telemetry. Large numbers of fishes were tagged in Rio Mameyes, Puerto Rico, U.S.A., with PITs and monitored at three fixed locations over a 2-5 year period to estimate transition probabilities between upper and lower elevations and survival probabilities with a multistate Cormack-Jolly-Seber model. A sub-set of fishes were tagged with radio-transmitters and tracked at weekly intervals to estimate fine-scale dispersal. Changes in spatial and temporal distributions of tagged fishes indicated that neither G. dormitor nor A. monticola moved into the lowest, estuarine reaches of Rio