Science.gov

Sample records for abstract coral bleaching

  1. Warm waters, bleached corals

    SciTech Connect

    Roberts, L.

    1990-10-12

    Two researchers, Tom Goreau of the Discovery Laboratory in Jamaica and Raymond Hayes of Howard University, claim that they have evidence that nearly clinches the temperature connection to the bleached corals in the Caribbean and that the coral bleaching is an indication of Greenhouse warming. The incidents of scattered bleaching of corals, which have been reported for decades, are increasing in both intensity and frequency. The researchers based their theory on increased temperature of the seas measured by satellites. However, some other scientists feel that the satellites measure the temperature of only the top few millimeters of the water and that since corals lie on reefs perhaps 60 to 100 feet below the ocean surface, the elevated temperatures are not significant.

  2. Hurricanes benefit bleached corals.

    PubMed

    Manzello, Derek P; Brandt, Marilyn; Smith, Tyler B; Lirman, Diego; Hendee, James C; Nemeth, Richard S

    2007-07-17

    Recent, global mass-mortalities of reef corals due to record warm sea temperatures have led researchers to consider global warming as one of the most significant threats to the persistence of coral reef ecosystems. The passage of a hurricane can alleviate thermal stress on coral reefs, highlighting the potential for hurricane-associated cooling to mitigate climate change impacts. We provide evidence that hurricane-induced cooling was responsible for the documented differences in the extent and recovery time of coral bleaching between the Florida Reef Tract and the U.S. Virgin Islands during the Caribbean-wide 2005 bleaching event. These results are the only known scenario where the effects of a hurricane can benefit a stressed marine community.

  3. Coral reef bleaching: ecological perspectives

    NASA Astrophysics Data System (ADS)

    Glynn, P. W.

    1993-03-01

    Coral reef bleaching, the whitening of diverse invertebrate taxa, results from the loss of symbiotic zooxanthellae and/or a reduction in photosynthetic pigment concentrations in zooxanthellae residing within the gastrodermal tissues of host animals. Of particular concern are the consequences of bleaching of large numbers of reef-building scleractinian corals and hydrocorals. Published records of coral reef bleaching events from 1870 to the present suggest that the frequency (60 major events from 1979 to 1990), scale (co-occurrence in many coral reef regions and often over the bathymetric depth range of corals) and severity (>95% mortality in some areas) of recent bleaching disturbances are unprecedented in the scientific literature. The causes of small scale, isolated bleaching events can often be explained by particular stressors (e.g., temperature, salinity, light, sedimentation, aerial exposure and pollutants), but attempts to explain large scale bleaching events in terms of possible global change (e.g., greenhouse warming, increased UV radiation flux, deteriorating ecosystem health, or some combination of the above) have not been convincing. Attempts to relate the severity and extent of large scale coral reef bleaching events to particular causes have been hampered by a lack of (a) standardized methods to assess bleaching and (b) continuous, long-term data bases of environmental conditions over the periods of interest. An effort must be made to understand the impact of bleaching on the remainder of the reef community and the long-term effects on competition, predation, symbioses, bioerosion and substrate condition, all factors that can influence coral recruitment and reef recovery. If projected rates of sea warming are realized by mid to late AD 2000, i.e. a 2°C increase in high latitude coral seas, the upper thermal tolerance limits of many reef-building corals could be exceeded. Present evidence suggests that many corals would be unable to adapt

  4. Coral bleaching: the role of the host.

    PubMed

    Baird, Andrew H; Bhagooli, Ranjeet; Ralph, Peter J; Takahashi, Shunichi

    2009-01-01

    Coral bleaching caused by global warming is one of the major threats to coral reefs. Very recently, research has focused on the possibility of corals switching symbionts as a means of adjusting to accelerating increases in sea surface temperature. Although symbionts are clearly of fundamental importance, many aspects of coral bleaching cannot be readily explained by differences in symbionts among coral species. Here we outline several potential mechanisms by which the host might influence the bleaching response, and conclude that predicting the fate of corals in response to climate change requires both members of the symbiosis to be considered equally.

  5. Patterns of coral bleaching: Modeling the adaptive bleaching hypothesis

    USGS Publications Warehouse

    Ware, J.R.; Fautin, D.G.; Buddemeier, R.W.

    1996-01-01

    Bleaching - the loss of symbiotic dinoflagellates (zooxanthellae) from animals normally possessing them - can be induced by a variety of stresses, of which temperature has received the most attention. Bleaching is generally considered detrimental, but Buddemeier and Fautin have proposed that bleaching is also adaptive, providing an opportunity for recombining hosts with alternative algal types to form symbioses that might be better adapted to altered circumstances. Our mathematical model of this "adaptive bleaching hypothesis" provides insight into how animal-algae symbioses might react under various circumstances. It emulates many aspects of the coral bleaching phenomenon including: corals bleaching in response to a temperature only slightly greater than their average local maximum temperature; background bleaching; bleaching events being followed by bleaching of lesser magnitude in the subsequent one to several years; higher thermal tolerance of corals subject to environmental variability compared with those living under more constant conditions; patchiness in bleaching; and bleaching at temperatures that had not previously resulted in bleaching. ?? 1996 Elsevier Science B.V. All rights reserved.

  6. Local stressors reduce coral resilience to bleaching.

    PubMed

    Carilli, Jessica E; Norris, Richard D; Black, Bryan A; Walsh, Sheila M; McField, Melanie

    2009-07-22

    Coral bleaching, during which corals lose their symbiotic dinoflagellates, typically corresponds with periods of intense heat stress, and appears to be increasing in frequency and geographic extent as the climate warms. A fundamental question in coral reef ecology is whether chronic local stress reduces coral resistance and resilience from episodic stress such as bleaching, or alternatively promotes acclimatization, potentially increasing resistance and resilience. Here we show that following a major bleaching event, Montastraea faveolata coral growth rates at sites with higher local anthropogenic stressors remained suppressed for at least 8 years, while coral growth rates at sites with lower stress recovered in 2-3 years. Instead of promoting acclimatization, our data indicate that background stress reduces coral fitness and resilience to episodic events. We also suggest that reducing chronic stress through local coral reef management efforts may increase coral resilience to global climate change.

  7. The role of microorganisms in coral bleaching.

    PubMed

    Rosenberg, Eugene; Kushmaro, Ariel; Kramarsky-Winter, Esti; Banin, Ehud; Yossi, Loya

    2009-02-01

    Coral bleaching is the disruption of the symbiosis between the coral host and its endosymbiotic algae. The prevalence and severity of the disease have been correlated with high seawater temperature. During the last decade, the major hypothesis to explain coral bleaching is that high water temperatures cause irreversible damage to the symbiotic algae resulting in loss of pigment and/or algae from the holobiont. Here, we discuss the evidence for an alternative but not mutually exclusive concept, the microbial hypothesis of coral bleaching.

  8. Coral bleaching: Thermal adaptation in reef coral symbionts

    NASA Astrophysics Data System (ADS)

    Rowan, Rob

    2004-08-01

    Many corals bleach as a result of increased seawater temperature, which causes them to lose their vital symbiotic algae (Symbiodinium spp.) - unless these symbioses are able to adapt to global warming, bleaching threatens coral reefs worldwide. Here I show that some corals have adapted to higher temperatures, at least in part, by hosting specifically adapted Symbiodinium. If other coral species can host these or similar Symbiodinium taxa, they might adapt to warmer habitats relatively easily.

  9. Coral bleaching independent of photosynthetic activity.

    PubMed

    Tolleter, Dimitri; Seneca, François O; DeNofrio, Jan C; Krediet, Cory J; Palumbi, Stephen R; Pringle, John R; Grossman, Arthur R

    2013-09-23

    The global decline of reef-building corals is due in part to the loss of algal symbionts, or "bleaching," during the increasingly frequent periods of high seawater temperatures. During bleaching, endosymbiotic dinoflagellate algae (Symbiodinium spp.) either are lost from the animal tissue or lose their photosynthetic pigments, resulting in host mortality if the Symbiodinium populations fail to recover. The >1,000 studies of the causes of heat-induced bleaching have focused overwhelmingly on the consequences of damage to algal photosynthetic processes, and the prevailing model for bleaching invokes a light-dependent generation of toxic reactive oxygen species (ROS) by heat-damaged chloroplasts as the primary trigger. However, the precise mechanisms of bleaching remain unknown, and there is evidence for involvement of multiple cellular processes. In this study, we asked the simple question of whether bleaching can be triggered by heat in the dark, in the absence of photosynthetically derived ROS. We used both the sea anemone model system Aiptasia and several species of reef-building corals to demonstrate that symbiont loss can occur rapidly during heat stress in complete darkness. Furthermore, we observed damage to the photosynthetic apparatus under these conditions in both Aiptasia endosymbionts and cultured Symbiodinium. These results do not directly contradict the view that light-stimulated ROS production is important in bleaching, but they do show that there must be another pathway leading to bleaching. Elucidation of this pathway should help to clarify bleaching mechanisms under the more usual conditions of heat stress in the light.

  10. Coral diseases and bleaching on Colombian Caribbean coral reefs.

    PubMed

    Navas-Camacho, Raúl; Gil-Agudelo, Diego Luis; Rodríguez-Ramírez, Alberto; Reyes-Nivia, María Catalina; Garzón-Ferreira, Jaime

    2010-05-01

    Since 1998 the National Monitoring System for the Coral Reefs of Colombia (SIMAC) has monitored the occurrence of coral bleaching and diseases in some Colombian coral reefs (permanent stations at San Andres Island, Rosario Islands, Tayrona, San Bernardo Islands and Urabá). The main purpose is to evaluate their health status and to understand the factors that have been contributing to their decline. To estimate these occurrences, annual surveys in 126 permanent belt transects (10 x 2m) with different depth intervals (3-6 meters, 9-12 meters and 15-18 meters) are performed at all reef sites. Data from the 1998-2004 period, revealed that San Andrés Island had many colonies with diseases (38.9 colonies/m2), and Urabá had high numbers with bleaching (54.4 colonies/m2). Of the seven reported coral diseases studied, Dark Spots Disease (DSD), and White Plague Disease (WPD) were noteworthy because they occurred in all Caribbean monitored sites, and because of their high interannual infection incidence. Thirty five species of scleractinian corals were affected by at least one disease and a high incidence of coral diseases on the main reef builders is documented. Bleaching was present in 34 species. During the whole monitoring period, Agaricia agaricites and Siderastrea siderea were the species most severely affected by DSD and bleaching, respectively. Diseases on species such as Agaricia fragilis, A. grahamae, A. humilis, Diploria clivosa, Eusmilia fastigiata, Millepora complanata, and Mycetophyllia aliciae are recorded for first time in Colombia. We present bleaching and disease incidences, kinds of diseases, coral species affected, reef localities studied, depth intervals of surveys, and temporal (years) variation for each geographic area. This variation makes difficult to clearly determine defined patterns or general trends for monitored reefs. This is the first long-term study of coral diseases and bleaching in the Southwestern Caribbean, and one of the few long

  11. Chronic parrotfish grazing impedes coral recovery after bleaching

    NASA Astrophysics Data System (ADS)

    Rotjan, Randi D.; Dimond, James L.; Thornhill, Daniel J.; Leichter, James J.; Helmuth, Brian; Kemp, Dustin W.; Lewis, Sara M.

    2006-08-01

    Coral bleaching, in which corals become visibly pale and typically lose their endosymbiotic zooxanthellae ( Symbiodinium spp.), increasingly threatens coral reefs worldwide. While the proximal environmental triggers of bleaching are reasonably well understood, considerably less is known concerning physiological and ecological factors that might exacerbate coral bleaching or delay recovery. We report a bleaching event in Belize during September 2004 in which Montastraea spp. corals that had been previously grazed by corallivorous parrotfishes showed a persistent reduction in symbiont density compared to intact colonies. Additionally, grazed corals exhibited greater diversity in the genetic composition of their symbiont communities, changing from uniform ITS2 type C7 Symbiodinium prior to bleaching to mixed assemblages of Symbiodinium types post-bleaching. These results suggest that chronic predation may exacerbate the influence of environmental stressors and, by altering the coral-zooxanthellae symbiosis, such abiotic-biotic interactions may contribute to spatial variation in bleaching processes.

  12. Does coral bleaching mean global warming

    SciTech Connect

    Miller, J.A.

    1991-02-01

    This article discusses the implications of global warming on the marine ecosystems. In recent hearings of the US Senate Committee on Commerce, Science and Transportation, plans were made to introduce legislation for control of greenhouse-gas emissions, conservation of biological diversity, forest conservation, world population planning, sustainable economic development , increased fuel efficiency, and increased research into Earth-system processes. Research is required to ascertain the meaning of coral bleaching, which is the mass expulsion of symbiotic algae, called zooxanthellae, which gives the coral its color. Many scientists think that the death of the algae is an early indicator for massive destruction of the marine ecosystem.

  13. Coral Bleaching: Coral 'refugia' amid heating seas

    NASA Astrophysics Data System (ADS)

    Caldeira, Ken

    2013-05-01

    The Earth is getting hotter as carbon dioxide, predominantly from the burning of fossil fuels, continues to accumulate in the atmosphere. It is widely recognized that increasing temperatures pose a threat to coral reefs, but just how large a risk are these reefs facing?

  14. The cumulative impact of annual coral bleaching can turn some coral species winners into losers.

    PubMed

    Grottoli, Andréa G; Warner, Mark E; Levas, Stephen J; Aschaffenburg, Matthew D; Schoepf, Verena; McGinley, Michael; Baumann, Justin; Matsui, Yohei

    2014-12-01

    Mass coral bleaching events caused by elevated seawater temperatures result in extensive coral loss throughout the tropics, and are projected to increase in frequency and severity. If bleaching becomes an annual event later in this century, more than 90% of coral reefs worldwide may be at risk of long-term degradation. While corals can recover from single isolated bleaching and can acclimate to recurring bleaching events that are separated by multiple years, it is currently unknown if and how they will survive and possibly acclimatize to annual coral bleaching. Here, we demonstrate for the first time that annual coral bleaching can dramatically alter thermal tolerance in Caribbean corals. We found that high coral energy reserves and changes in the dominant algal endosymbiont type (Symbiodinium spp.) facilitated rapid acclimation in Porites divaricata, whereas low energy reserves and a lack of algal phenotypic plasticity significantly increased susceptibility in Porites astreoides to bleaching the following year. Phenotypic plasticity in the dominant endosymbiont type of Orbicella faveolata did not prevent repeat bleaching, but may have facilitated rapid recovery. Thus, coral holobiont response to an isolated single bleaching event is not an accurate predictor of its response to bleaching the following year. Rather, the cumulative impact of annual coral bleaching can turn some coral species 'winners' into 'losers', and can also facilitate acclimation and turn some coral species 'losers' into 'winners'. Overall, these findings indicate that cumulative impact of annual coral bleaching could result in some species becoming increasingly susceptible to bleaching and face a long-term decline, while phenotypically plastic coral species will acclimatize and persist. Thus, annual coral bleaching and recovery could contribute to the selective loss of coral diversity as well as the overall decline of coral reefs in the Caribbean.

  15. The 2014 summer coral bleaching event in subtropical Hong Kong.

    PubMed

    Xie, James Y; Lau, Dickey C C; Kei, Keith; Yu, Vriko P F; Chow, Wing-Kuen; Qiu, Jian-Wen

    2017-04-06

    We reported a coral bleaching event that occurred in August-September 2014 in Hong Kong waters based on video transect surveys conducted at eight sites. The bleaching affected eight species of corals with different growth forms. Bleaching at seven of the eight study sites was minor, affecting only 0.4-5.2% colonies and 0.8-10.0% coral-covered area. Sharp Island East, however, suffered from a moderate level of bleaching, with 13.1% colonies and 30.1% coral-covered area affected. Examination of the government's environmental monitoring data indicated abnormal water quality conditions preceding and during the bleaching event. Follow-up field surveys of tagged colonies showed that 76% of them had fully recovered, 12% partially recovered, and 12% suffered from mortality. These results indicate that the subtropical corals of Hong Kong are not immune to bleaching, and there is a need to study their responses under climate change scenarios.

  16. Coral community response to bleaching on a highly disturbed reef

    NASA Astrophysics Data System (ADS)

    Guest, J. R.; Low, J.; Tun, K.; Wilson, B.; Ng, C.; Raingeard, D.; Ulstrup, K. E.; Tanzil, J. T. I.; Todd, P. A.; Toh, T. C.; McDougald, D.; Chou, L. M.; Steinberg, P. D.

    2016-02-01

    While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress.

  17. Coral community response to bleaching on a highly disturbed reef

    PubMed Central

    Guest, J. R.; Low, J.; Tun, K.; Wilson, B.; Ng, C.; Raingeard, D.; Ulstrup, K. E.; Tanzil, J. T. I.; Todd, P. A.; Toh, T. C.; McDougald, D.; Chou, L. M.; Steinberg, P. D.

    2016-01-01

    While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress. PMID:26876092

  18. Coral community response to bleaching on a highly disturbed reef.

    PubMed

    Guest, J R; Low, J; Tun, K; Wilson, B; Ng, C; Raingeard, D; Ulstrup, K E; Tanzil, J T I; Todd, P A; Toh, T C; McDougald, D; Chou, L M; Steinberg, P D

    2016-02-15

    While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress.

  19. Incorporating adaptive responses into future projections of coral bleaching.

    PubMed

    Logan, Cheryl A; Dunne, John P; Eakin, C Mark; Donner, Simon D

    2014-01-01

    Climate warming threatens to increase mass coral bleaching events, and several studies have projected the demise of tropical coral reefs this century. However, recent evidence indicates corals may be able to respond to thermal stress though adaptive processes (e.g., genetic adaptation, acclimatization, and symbiont shuffling). How these mechanisms might influence warming-induced bleaching remains largely unknown. This study compared how different adaptive processes could affect coral bleaching projections. We used the latest bias-corrected global sea surface temperature (SST) output from the NOAA/GFDL Earth System Model 2 (ESM2M) for the preindustrial period through 2100 to project coral bleaching trajectories. Initial results showed that, in the absence of adaptive processes, application of a preindustrial climatology to the NOAA Coral Reef Watch bleaching prediction method overpredicts the present-day bleaching frequency. This suggests that corals may have already responded adaptively to some warming over the industrial period. We then modified the prediction method so that the bleaching threshold either permanently increased in response to thermal history (e.g., simulating directional genetic selection) or temporarily increased for 2-10 years in response to a bleaching event (e.g., simulating symbiont shuffling). A bleaching threshold that changes relative to the preceding 60 years of thermal history reduced the frequency of mass bleaching events by 20-80% compared with the 'no adaptive response' prediction model by 2100, depending on the emissions scenario. When both types of adaptive responses were applied, up to 14% more reef cells avoided high-frequency bleaching by 2100. However, temporary increases in bleaching thresholds alone only delayed the occurrence of high-frequency bleaching by ca. 10 years in all but the lowest emissions scenario. Future research should test the rate and limit of different adaptive responses for coral species across latitudes and

  20. Coral bleaching: a potential biomarker of environmental stress.

    PubMed

    Meehan, W J; Ostrander, G K

    1997-04-25

    Coral bleaching refers to the loss of symbiotic algae by host corals, or to the loss of pigmentation by the algae themselves, causing corals to appear white or "bleached." Some corals may regain algae or pigmentation and survive, but when bleaching is severe the host coral dies. Coral bleaching events have increased dramatically in the last two decades, and coral reefs throughout the world have been extensively degraded as a result. This article reviews coral bleaching for investigators working in the field of toxicology and environmental health, a group of scientists not normally exposed to this issue. Several environmental stressors have been correlated with bleaching, including fluctuations in sea surface temperatures and salinity, increased sedimentation, increased solar radiation, and contaminants such as oil and herbicides. Molecular mechanisms of bleaching are only beginning to be investigated and are thus far poorly understood. Toxicologists have the potential to make significant contributions toward understanding anthropogenic aspects of coral bleaching and elucidating molecular mechanisms of this important environmental problem.

  1. Coral reef bleaching at Agatti Island of Lakshadweep atolls, India

    NASA Astrophysics Data System (ADS)

    Vinoth, Ramar; Gopi, Mohan; Kumar, Thipramalai Thankappanpillai Ajith; Thangaradjou, Thirunavukarassu; Balasubramanian, Thangavel

    2012-03-01

    A survey on coral bleaching was carried out at Agatti Island of Lakshadweep from May to June 2010. Elevated sea surface temperatures (SSTs) of the region exceeded the seasonal average and delayed the onset of monsoon, which triggered widespread bleaching of corals. The Agatti reefs showed an average of 73% bleached corals with apparent bleaching-related mortality of sea anemones (87%) and giant clams (83%). The SST increased up to 34 °C with an average maximum SST of 32.5 during the study °C period between May and June 2010. Coral reefs on the southern side of the island are fully or partially exposed to sun light during low tide in contrast to the other side. This suggests that the mortality is more likely due to the low tide exposure than exclusively due to the elevated SST. Observations indicated a clear increase in coral bleaching during April 2010, at levels higher than that in normal summer.

  2. Coral bleaching--capacity for acclimatization and adaptation.

    PubMed

    Coles, S L; Brown, Barbara E

    2003-01-01

    Coral bleaching, i.e., loss of most of the symbiotic zooxanthellae normally found within coral tissue, has occurred with increasing frequency on coral reefs throughout the world in the last 20 years, mostly during periods of El Nino Southern Oscillation (ENSO). Experiments and observations indicate that coral bleaching results primarily from elevated seawater temperatures under high light conditions, which increases rates of biochemical reactions associated with zooxanthellar photosynthesis, producing toxic forms of oxygen that interfere with cellular processes. Published projections of a baseline of increasing ocean temperature resulting from global warming have suggested that annual temperature maxima within 30 years may be at levels that will cause frequent coral bleaching and widespread mortality leading to decline of corals as dominant organisms on reefs. However, these projections have not considered the high variability in bleaching response that occurs among corals both within and among species. There is information that corals and their symbionts may be capable of acclimatization and selective adaptation to elevated temperatures that have already resulted in bleaching resistant coral populations, both locally and regionally, in various areas of the world. There are possible mechanisms that might provide resistance and protection to increased temperature and light. These include inducible heat shock proteins that act in refolding denatured cellular and structural proteins, production of oxidative enzymes that inactivate harmful oxygen radicals, fluorescent coral pigments that both reflect and dissipate light energy, and phenotypic adaptations of zooxanthellae and adaptive shifts in their populations at higher temperatures. Such mechanisms, when considered in conjunction with experimental and observational evidence for coral recovery in areas that have undergone coral bleaching, suggest an as yet undefined capacity in corals and zooxanthellae to adapt to

  3. Mass coral bleaching in 2010 in the southern Caribbean.

    PubMed

    Alemu I, Jahson Berhane; Clement, Ysharda

    2014-01-01

    Ocean temperatures are increasing globally and the Caribbean is no exception. An extreme ocean warming event in 2010 placed Tobago's coral reefs under severe stress resulting in widespread coral bleaching and threatening the livelihoods that rely on them. The bleaching response of four reef building taxa was monitored over a six month period across three major reefs systems in Tobago. By identifying taxa resilient to bleaching we propose to assist local coral reef managers in the decision making process to cope with mass bleaching events. The bleaching signal (length of exposure to high ocean temperatures) varied widely between the Atlantic and Caribbean reefs, but regardless of this variation most taxa bleached. Colpophyllia natans, Montastraea faveolata and Siderastrea siderea were considered the most bleaching vulnerable taxa. Interestingly, reefs with the highest coral cover showed the greatest decline reef building taxa, and conversely, reefs with the lowest coral cover showed the most bleaching but lowest change in coral cover with little algal overgrowth post-bleaching.

  4. Bacteria associated with the bleached and cave coral Oculina patagonica.

    PubMed

    Koren, Omry; Rosenberg, Eugene

    2008-04-01

    The relative abundance of bacteria in the mucus and tissues of Oculina patagonica taken from bleached and cave (azooxanthellae) corals was determined by analyses of the 16S rRNA genes from cloned libraries of extracted DNA and from isolated colonies. The results were compared to previously published data on healthy O. patagonica. The bacterial community of bleached, cave, and healthy corals were completely different from each other. A tight cluster (>99.5% identity) of bacteria, showing 100% identity to Acinetobacter species, dominated bleached corals, comprising 25% of the 316 clones sequenced. The dominant bacterial cluster found in cave corals, representing 29% of the 97 clones sequenced, showed 98% identity to an uncultured bacterium from the Great Barrier Reef. Vibrio splendidus was the most dominant species in healthy O. patagonica. The culturable bacteria represented 0.1-1.0% of the total bacteria (SYBR Gold staining) of the corals. The most abundant culturable bacteria in bleached, cave, and healthy corals were clusters that most closely matched Microbulbifer sp., an alpha-proteobacterium previously isolated from healthy corals and an alpha-protobacterium (AB026194), respectively. Three generalizations emerge from this study on O. patagonica: (1) More bacteria are associated with coral tissue than mucus; (2) tissue and mucus populations are different; (3) bacterial populations associated with corals change dramatically when corals lack their symbiotic zooxanthellae, either as a result of the bleaching disease or when growing in the absence of light.

  5. Through bleaching and tsunami: Coral reef recovery in the Maldives.

    PubMed

    Morri, Carla; Montefalcone, Monica; Lasagna, Roberta; Gatti, Giulia; Rovere, Alessio; Parravicini, Valeriano; Baldelli, Giuseppe; Colantoni, Paolo; Bianchi, Carlo Nike

    2015-09-15

    Coral reefs are degrading worldwide, but little information exists on their previous conditions for most regions of the world. Since 1989, we have been studying the Maldives, collecting data before, during and after the bleaching and mass mortality event of 1998. As early as 1999, many newly settled colonies were recorded. Recruits shifted from a dominance of massive and encrusting corals in the early stages of recolonisation towards a dominance of Acropora and Pocillopora by 2009. Coral cover, which dropped to less than 10% after the bleaching, returned to pre-bleaching values of around 50% by 2013. The 2004 tsunami had comparatively little effect. In 2014, the coral community was similar to that existing before the bleaching. According to descriptors and metrics adopted, recovery of Maldivian coral reefs took between 6 and 15years, or may even be considered unachieved, as there are species that had not come back yet.

  6. Effects of coral bleaching on the obligate coral-dwelling crab Trapezia cymodoce

    NASA Astrophysics Data System (ADS)

    Stella, J. S.; Munday, P. L.; Jones, G. P.

    2011-09-01

    Corals are an essential and threatened habitat for a diverse range of reef-associated animals. Episodes of coral bleaching are predicted to increase in frequency and intensity over coming decades, yet the effects of coral-host bleaching on the associated animal communities remain poorly understood. The present study investigated the effects of host-colony bleaching on the obligate coral-dwelling crab, Trapezia cymodoce, during a natural bleaching event in the lagoon of Lizard Island, Australia. Branching corals, which harbour the highest diversity of coral associates, comprised 13% of live coral cover at the study site, with 83% affected by bleaching. Crabs on healthy and bleached colonies of Pocillopora damicornis were monitored over a 5-week period to determine whether coral bleaching affected crab density and movement patterns. All coral colonies initially contained one breeding pair of crabs. There was a significant decline in crab density on bleached corals after 5 weeks, with many corals losing one or both crabs, yet all healthy colonies retained a mating pair. Fecundity of crabs collected from bleached and healthy colonies of P. damicornis was also compared. The size of egg clutches of crabs collected from bleached hosts was 40% smaller than those from healthy hosts, indicating a significant reduction in fecundity. A laboratory experiment on movement patterns found that host-colony bleaching also prompted crabs to emigrate in search of more suitable colonies. Emigrant crabs engaged in aggressive interactions with occupants of healthy hosts, with larger crabs always usurping occupants of a smaller size. Decreased densities and clutch sizes, along with increased competitive interactions, could potentially result in a population decline of these important coral associates with cascading effects on coral health.

  7. Global warming and recurrent mass bleaching of corals

    NASA Astrophysics Data System (ADS)

    Hughes, Terry P.; Kerry, James T.; Álvarez-Noriega, Mariana; Álvarez-Romero, Jorge G.; Anderson, Kristen D.; Baird, Andrew H.; Babcock, Russell C.; Beger, Maria; Bellwood, David R.; Berkelmans, Ray; Bridge, Tom C.; Butler, Ian R.; Byrne, Maria; Cantin, Neal E.; Comeau, Steeve; Connolly, Sean R.; Cumming, Graeme S.; Dalton, Steven J.; Diaz-Pulido, Guillermo; Eakin, C. Mark; Figueira, Will F.; Gilmour, James P.; Harrison, Hugo B.; Heron, Scott F.; Hoey, Andrew S.; Hobbs, Jean-Paul A.; Hoogenboom, Mia O.; Kennedy, Emma V.; Kuo, Chao-Yang; Lough, Janice M.; Lowe, Ryan J.; Liu, Gang; McCulloch, Malcolm T.; Malcolm, Hamish A.; McWilliam, Michael J.; Pandolfi, John M.; Pears, Rachel J.; Pratchett, Morgan S.; Schoepf, Verena; Simpson, Tristan; Skirving, William J.; Sommer, Brigitte; Torda, Gergely; Wachenfeld, David R.; Willis, Bette L.; Wilson, Shaun K.

    2017-03-01

    During 2015–2016, record temperatures triggered a pan-tropical episode of coral bleaching, the third global-scale event since mass bleaching was first documented in the 1980s. Here we examine how and why the severity of recurrent major bleaching events has varied at multiple scales, using aerial and underwater surveys of Australian reefs combined with satellite-derived sea surface temperatures. The distinctive geographic footprints of recurrent bleaching on the Great Barrier Reef in 1998, 2002 and 2016 were determined by the spatial pattern of sea temperatures in each year. Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. Consequently, immediate global action to curb future warming is essential to secure a future for coral reefs.

  8. Global warming and recurrent mass bleaching of corals.

    PubMed

    Hughes, Terry P; Kerry, James T; Álvarez-Noriega, Mariana; Álvarez-Romero, Jorge G; Anderson, Kristen D; Baird, Andrew H; Babcock, Russell C; Beger, Maria; Bellwood, David R; Berkelmans, Ray; Bridge, Tom C; Butler, Ian R; Byrne, Maria; Cantin, Neal E; Comeau, Steeve; Connolly, Sean R; Cumming, Graeme S; Dalton, Steven J; Diaz-Pulido, Guillermo; Eakin, C Mark; Figueira, Will F; Gilmour, James P; Harrison, Hugo B; Heron, Scott F; Hoey, Andrew S; Hobbs, Jean-Paul A; Hoogenboom, Mia O; Kennedy, Emma V; Kuo, Chao-Yang; Lough, Janice M; Lowe, Ryan J; Liu, Gang; McCulloch, Malcolm T; Malcolm, Hamish A; McWilliam, Michael J; Pandolfi, John M; Pears, Rachel J; Pratchett, Morgan S; Schoepf, Verena; Simpson, Tristan; Skirving, William J; Sommer, Brigitte; Torda, Gergely; Wachenfeld, David R; Willis, Bette L; Wilson, Shaun K

    2017-03-15

    During 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching, the third global-scale event since mass bleaching was first documented in the 1980s. Here we examine how and why the severity of recurrent major bleaching events has varied at multiple scales, using aerial and underwater surveys of Australian reefs combined with satellite-derived sea surface temperatures. The distinctive geographic footprints of recurrent bleaching on the Great Barrier Reef in 1998, 2002 and 2016 were determined by the spatial pattern of sea temperatures in each year. Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. Consequently, immediate global action to curb future warming is essential to secure a future for coral reefs.

  9. A novel paleo-bleaching proxy using boron isotopes and high-resolution laser ablation to reconstruct coral bleaching events

    NASA Astrophysics Data System (ADS)

    Dishon, G.; Fisch, J.; Horn, I.; Kaczmarek, K.; Bijma, J.; Gruber, D. F.; Nir, O.; Popovich, Y.; Tchernov, D.

    2015-06-01

    Coral reefs occupy only ~0.1% of the oceans habitat, but are the most biologically diverse marine ecosystem. In recent decades, coral reefs have experienced significant global declines due to a variety of causes, one of the major being widespread coral bleaching events. During bleaching the coral expels its symbiotic algae losing its main source of nutrition generally obtained through photosynthesis. While recent coral bleaching events have been extensively investigated, there is no scientific data on historical coral bleaching prior to 1979. In this study, we employ high-resolution femtosecond Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) to demonstrate a distinct biologically-induced decline of boron (B) isotopic composition (δ11B) as a result of coral bleaching. These findings and methodology offer a new use for a previously developed isotopic proxy to reconstruct paleo-coral bleaching events. Based on a literature review of published δ11B data and our recorded "vital effect" of coral bleaching on the δ11B signal, we also describe at least two possible coral bleaching events since the Last Glacial Maximum. The implementation of this bleaching proxy holds the potential of identifying occurrences of coral bleaching throughout the geological record. A deeper temporal view of coral bleaching will enable scientists to determine if it occurred in the past during times of environmental change and what outcome it may have had on coral population structure.

  10. THE CONDITION OF CORAL REEFS IN SOUTH FLORIDA (2000) USING CORAL DISEASE AND BLEACHING AS INDICATORS

    EPA Science Inventory

    The destruction for coral reef habitats is occurring at unprecedented levels. Coral disease epizootics in the Southwestern Atlantic have lead to coral replacement by turf algae, prompting a call to classify some coral species as endangered. In addition, a massive bleaching event ...

  11. The effects of habitat on coral bleaching responses in Kenya.

    PubMed

    Grimsditch, Gabriel; Mwaura, Jelvas M; Kilonzo, Joseph; Amiyo, Nassir

    2010-06-01

    This study examines the bleaching responses of scleractinian corals at four sites in Kenya (Kanamai, Vipingo, Mombasa and Nyali) representing two distinct lagoon habitats (relatively shallow and relatively deep). Bleaching incidence was monitored for the whole coral community, while zooxanthellae densities and chlorophyll levels were monitored for target species (Pocillopora damicornis, Porites lutea, and Porites cylindrica) during a non-bleaching year (2006) and a year of mild-bleaching (2007). Differences in bleaching responses between habitats were observed, with shallower sites Kanamai and Vipingo exhibiting lower bleaching incidence than deeper sites Nyali and Mombasa. These shallower lagoons display more fluctuating thermal and light environments than the deeper sites, suggesting that corals in the shallower lagoons have acclimatized and/or adapted to the fluctuating environmental conditions they endure on a daily basis and have become more resistant to bleaching stress. In deeper sites that did exhibit higher bleaching (Mombasa and Nyali), it was found that coral recovery occurred more quickly in the protected area than in the non-protected area.

  12. INDICATORS OF UV EXPOSURE IN CORALS AND THEIR RELEVANCE TO GLOBAL CLIMATE CHANGE AND CORAL BLEACHING

    EPA Science Inventory

    A compelling aspect of the deterioration of coral reefs is the phenomenon of coral bleaching. Through interactions with other factors such as sedimentation, pollution, and bacterial infection, bleaching can impact large areas of a reef with limited recovery, and it might be induc...

  13. INDICATORS OF UV EXPOSURE IN CORAL AND THEIR RELEVANCE TO GLOBAL CLIMATE CHANGE AND CORAL BLEACHING

    EPA Science Inventory

    A compelling aspect of the deterioration of coral reefs is the phenomenon of coral bleaching. Bleaching can destroy large areas of a reef with limited recovery or recruitment, and it may be induced by a variety of stressors ranging from exposure to temperature and salinity extrem...

  14. The effects of coral bleaching on settlement preferences and growth of juvenile butterflyfishes.

    PubMed

    Cole, A J; Lawton, R J; Pisapia, C; Pratchett, M S

    2014-07-01

    Coral bleaching and associated mortality is an increasingly prominent threat to coral reef ecosystems. Although the effects of bleaching-induced coral mortality on reef fishes have been well demonstrated, corals can remain bleached for several weeks prior to recovery or death and little is known about how bleaching affects resident fishes during this time period. This study compared growth rates of two species of juvenile butterflyfishes (Chaetodon aureofasciatus and Chaetodon lunulatus) that were restricted to feeding upon either bleached or healthy coral tissue of Acropora spathulata or Pocillopora damicornis. Coral condition (bleached vs. unbleached) had no significant effects on changes in total length or weight over a 23-day period. Likewise, in a habitat choice experiment, juvenile butterflyfishes did not discriminate between healthy and bleached corals, but actively avoided using recently dead colonies. These results indicate that juvenile coral-feeding fishes are relatively robust to short term effects of bleaching events, provided that the corals do recover.

  15. Climatological context for large-scale coral bleaching

    NASA Astrophysics Data System (ADS)

    Barton, A. D.; Casey, K. S.

    2005-12-01

    Large-scale coral bleaching was first observed in 1979 and has occurred throughout virtually all of the tropics since that time. Severe bleaching may result in the loss of live coral and in a decline of the integrity of the impacted coral reef ecosystem. Despite the extensive scientific research and increased public awareness of coral bleaching, uncertainties remain about the past and future of large-scale coral bleaching. In order to reduce these uncertainties and place large-scale coral bleaching in the longer-term climatological context, specific criteria and methods for using historical sea surface temperature (SST) data to examine coral bleaching-related thermal conditions are proposed by analyzing three, 132 year SST reconstructions: ERSST, HadISST1, and GISST2.3b. These methodologies are applied to case studies at Discovery Bay, Jamaica (77.27°W, 18.45°N), Sombrero Reef, Florida, USA (81.11°W, 24.63°N), Academy Bay, Galápagos, Ecuador (90.31°W, 0.74°S), Pearl and Hermes Reef, Northwest Hawaiian Islands, USA (175.83°W, 27.83°N), Midway Island, Northwest Hawaiian Islands, USA (177.37°W, 28.25°N), Davies Reef, Australia (147.68°E, 18.83°S), and North Male Atoll, Maldives (73.35°E, 4.70°N). The results of this study show that (1) The historical SST data provide a useful long-term record of thermal conditions in reef ecosystems, giving important insight into the thermal history of coral reefs and (2) While coral bleaching and anomalously warm SSTs have occurred over much of the world in recent decades, case studies in the Caribbean, Northwest Hawaiian Islands, and parts of other regions such as the Great Barrier Reef exhibited SST conditions and cumulative thermal stress prior to 1979 that were comparable to those conditions observed during the strong, frequent coral bleaching events since 1979. This climatological context and knowledge of past environmental conditions in reef ecosystems may foster a better understanding of how coral reefs will

  16. Coral bleaching response index: a new tool to standardize and compare susceptibility to thermal bleaching.

    PubMed

    Swain, Timothy D; Vega-Perkins, Jesse B; Oestreich, William K; Triebold, Conrad; DuBois, Emily; Henss, Jillian; Baird, Andrew; Siple, Margaret; Backman, Vadim; Marcelino, Luisa

    2016-07-01

    As coral bleaching events become more frequent and intense, our ability to predict and mitigate future events depends upon our capacity to interpret patterns within previous episodes. Responses to thermal stress vary among coral species; however the diversity of coral assemblages, environmental conditions, assessment protocols, and severity criteria applied in the global effort to document bleaching patterns creates challenges for the development of a systemic metric of taxon-specific response. Here, we describe and validate a novel framework to standardize bleaching response records and estimate their measurement uncertainties. Taxon-specific bleaching and mortality records (2036) of 374 coral taxa (during 1982-2006) at 316 sites were standardized to average percent tissue area affected and a taxon-specific bleaching response index (taxon-BRI) was calculated by averaging taxon-specific response over all sites where a taxon was present. Differential bleaching among corals was widely variable (mean taxon-BRI = 25.06 ± 18.44%, ±SE). Coral response may differ because holobionts are biologically different (intrinsic factors), they were exposed to different environmental conditions (extrinsic factors), or inconsistencies in reporting (measurement uncertainty). We found that both extrinsic and intrinsic factors have comparable influence within a given site and event (60% and 40% of bleaching response variance of all records explained, respectively). However, when responses of individual taxa are averaged across sites to obtain taxon-BRI, differential response was primarily driven by intrinsic differences among taxa (65% of taxon-BRI variance explained), not conditions across sites (6% explained), nor measurement uncertainty (29% explained). Thus, taxon-BRI is a robust metric of intrinsic susceptibility of coral taxa. Taxon-BRI provides a broadly applicable framework for standardization and error estimation for disparate historical records and collection of novel

  17. A novel paleo-bleaching proxy using boron isotopes and high-resolution laser ablation to reconstruct coral bleaching events

    NASA Astrophysics Data System (ADS)

    Dishon, G.; Fisch, J.; Horn, I.; Kaczmarek, K.; Bijma, J.; Gruber, D. F.; Nir, O.; Popovich, Y.; Tchernov, D.

    2015-10-01

    Coral reefs occupy only ~ 0.1 percent of the ocean's habitat, but are the most biologically diverse marine ecosystem. In recent decades, coral reefs have experienced a significant global decline due to a variety of causes, one of the major causes being widespread coral bleaching events. During bleaching, the coral expels its symbiotic algae, thereby losing its main source of nutrition generally obtained through photosynthesis. While recent coral bleaching events have been extensively investigated, there is no scientific data on historical coral bleaching prior to 1979. In this study, we employ high-resolution femtosecond Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) to demonstrate a distinct biologically induced decline of boron (B) isotopic composition (δ11B) as a result of coral bleaching. These findings and methodology offer a new use for a previously developed isotopic proxy to reconstruct paleo-coral bleaching events. Based on a literature review of published δ11B data and our recorded vital effect of coral bleaching on the δ11B signal, we also describe at least two possible coral bleaching events since the Last Glacial Maximum. The implementation of this bleaching proxy holds the potential of identifying occurrences of coral bleaching throughout the geological record. A deeper temporal view of coral bleaching will enable scientists to determine if it occurred in the past during times of environmental change and what outcome it may have had on coral population structure. Understanding the frequency of bleaching events is also critical for determining the relationship between natural and anthropogenic causes of these events.

  18. Impacts of the 1998 and 2010 mass coral bleaching events on the Western Gulf of Thailand

    NASA Astrophysics Data System (ADS)

    Sutthacheep, Makamas; Yucharoen, Mathinee; Klinthong, Wanlaya; Pengsakun, Sittiporn; Sangmanee, Kanwara; Yeemin, Thamasak

    2013-11-01

    A long-term study of coral reef ecology in the Gulf of Thailand provides a good opportunity to examine the temporal variation on the impact of mass coral bleaching at those reef sites. We compared the bleaching and mortality of corals between the mass bleaching events in 1998 and 2010 at a coral community in the Western Gulf of Thailand. The aim was to identify the coral species which were most likely to suffer from (and to be able to tolerate) changes in seawater temperature. Significant differences in the susceptibility of the coral taxa to bleaching events between the years 1998 and 2010 and among coral species were documented. Bleaching was significantly different between the most dominant corals. Diploastrea heliopora was the most resistant coral to bleaching in both years. Some coral species showed more resistance to bleaching in 2010. The coral mortality following the mass bleaching events in 1998 and 2010 varied significantly between the years and the coral taxa. Mortality of some dominant coral taxa was also lower in 2010. Seven coral species, i.e. Astreopora myriophthalma, Pachyseris rugosa, Turbinaria mesenterina, Goniastrea pectinata, Favia pallida, F. maritima, Favites halicora, Platygyra daedalea and Galaxea fascicularis, were tolerant to the coral bleaching events. An ecosystem-based approach to managing coral reefs in the Gulf of Thailand is needed to identify appropriate marine protected area networks and to strengthen marine and coastal resource policies in order to build coral reef resilience.

  19. Project Overview: A Reef Manager's Guide to Coral Bleaching ...

    EPA Pesticide Factsheets

    The purpose of this report is to provide the latest scientific knowledge and discuss available management options to assist local and regional managers in responding effectively to mass coral bleaching events. Background A Reef Manager’s Guide to Coral Bleaching is the result of a collaborative effort by over 50 scientists and managers to: (1) share the best available scientific information on climate-related coral bleaching; and (2) compile a tool kit of currently available strategies for adaptive management of coral reefs in a changing climate. The result is a compendium of current information, tools, and practical suggestions to aid managers in their efforts to protect reefs in a way that maximizes reef resilience in the face of continuing climate change. The Guide is a joint publication of the National Oceanic and Atmospheric Administration, the Great Barrier Reef Marine Park Authority, and The World Conservation Union, with author contributions from a variety of international partners from government agencies, non-governmental organizations, and academic institutions. EPA’s Office of Research and Development was a major contributor to the Guide through authorship and participation in the final review and editing process for the entire report. A Reef Manager’s Guide to Coral Bleaching is the result of a collaborative effort by over 50 scientists and managers to: (1) share the best available scientific information on climate-related coral blea

  20. The condition of coral reefs in South Florida (2000) using Coral disease and bleaching as indicators.

    PubMed

    Santavy, Deborah L; Summers, J Kevin; Engle, Virginia D; Harwell, Linda C

    2005-01-01

    The destruction of coral reef habitats has occurred at unprecedented levels during the last three decades. Coral disease and bleaching in the Caribbean and South Florida have caused extensive coral mortality with limited recovery, often coral reefs are being replaced with turf algae. Acroporids were once dominant corals and have diminished to the state where they are being considered as endangered species. Our survey assessed the condition of reef corals throughout South Florida. A probability-based design produced unbiased estimates of the spatial extent of ecological condition, measured as the absence or presence and frequency or prevalence of coral diseases and bleaching intensity over large geographic regions. This approach allowed us to calculate a quantifiable level of uncertainty. Coral condition was estimated for 4100 hectares (ha) (or 41.0 km2) of coral reefs in South Florida, including reefs in the Florida Keys National Marine Sanctuary (FKNMS), New Grounds, Dry Tortugas National Park (DTNP), and Biscayne National Park (BNP). The absence or presence of coral disease, 'causal' coral bleaching, partial bleaching and coral paling were not good indicators of overall coral condition. It was more useful to report the prevalence of anomalies that indicated a compromised condition at both the population and community levels. For example, 79% of the area in South Florida had less than 6% of the coral colonies diseased, whereas only 2.2% (97.15 ha) of the sampled area had a maximum prevalence of 13% diseased coral colonies at any single location. The usefulness of 'causal bleaching' might be more important when considering the prevalence of each of the three different states at a single location. For example, paling was observed over the entire area, whereas bleaching and partial bleaching occurred at 19 and 41% of the area, respectively. An index for coral reef condition might integrate the prevalence and species affected by each bleaching state at individual

  1. Ocean Acidification: A Major Driver of Coral Bleaching in the 21st Century?

    NASA Astrophysics Data System (ADS)

    Anthony, K.; Eakin, M. C.; Cao, L.; Caldeira, K.; Hoegh-Guldberg, O.

    2009-05-01

    Heat stress long been known to drive patterns of coral bleaching. Recently, however, it was discovered that ocean acidification can drive coral bleaching independently of temperature. This raises the question: how important will acidification be in driving coral bleaching under climate change? Here, we develop and apply a model that accounts for both thermal stress and ocean acidification in the coral bleaching response. Our analyses, which combine experimental bleaching data under manipulated ocean chemistry and warming with projections of CO2 and SST based on global circulation models, show that ocean acidification will become a key driver of future mass bleaching events within a few decades. Our findings, based on highly conservative assumptions, reveal that coral bleaching alert systems based on warming alone could underestimate coral bleaching by up to 50% during the 21st century. This is a striking result that will affect coral reef management strategies worldwide and has policy implications relating to global efforts to reduce greenhouse gas emissions.

  2. Change in CO2 Flux in Coral Reefs by Bleaching

    NASA Astrophysics Data System (ADS)

    Kayanne, H.; Kayanne, H.; Watanabe, A.; Hata, H.; Kudo, S.; Nozaki, K.; Kato, K.; Negishi, A.; Saito, H.

    2001-05-01

    Coral reefs are related with carbon cycles through photosynthesis, respiration and calcification. Photosynthesis acts as sink of CO2, though respiration and calcification act as source of CO2. The role of coral reef ecosystem to atmospheric CO2 changes with balance among these community-level metabolisms. The world-wide coral reef bleaching in 1997-1998 provided us with a chance to evaluate the role of the metabolic processes of coral reefs to carbon cycles. In Ishigaki Island, Ryukyu Islands, southwest Japan and Palau Islands, west of Caroline Islands, we measured CO2 in reef water and community metabolisms by change in seawater alkalinity and total inorganic carbon. The observtion were conducted during and after bleaching in Ishigaki Island, and before and after bleaching in Palau Islands. Higher rates of community gross primary production (Pg) and respiration (R), and lower rate of net community production (Pn) were observed for the community with extensive bleaching. Calcification rate (G) was almost the same. The resultant increase in magnitude of diurnal change in CO2 were observed, and the community acted as net source of CO2. Lower rates of Pg, R, Pn, G and resultant smaller variation in diurnal CO2 change were observed for the community of dead corals and filamentous brown algae. This also resulted in shift of the community CO2 flux to net source of CO2. Bleaching shifted the function of coral reef ecosystem from sink or small source to large source of CO2. More severe and extensive bleaching is predicted to be occurred during the global warming, which acted as positive feedback to CO2 increase, and thus, global warming.

  3. The Impact of Tropical Cyclones on Coral Bleaching and Coral Diseases

    NASA Astrophysics Data System (ADS)

    van Hooidonk, R. J.; Huber, M.

    2006-12-01

    Tropical cyclones (TCs) impact coral reef ecology in various ways, they cool down ambient sea surface temperature (SST), damage coral reefs by wave action, decrease salinity, increase nutrients, and increase sedimentation rates on a reef. Here we present an investigation into the effect of TCs on coral bleaching and the effect TCs have on the occurrence of coral diseases. Coral bleaching, the condition where the symbiotic zooxanthellae leave the coral host, is one of the major threats to coral reefs. Bleaching occurs in anomalously warm waters, analysis of historical TC tracks show that TCs frequently occur near coral bleaching episodes. Intriguingly, TCs cool down sea surface temperature by vertical mixing and as SST is the most important factor in coral bleaching this phenomenon might have an impact on the duration, occurrence and the resulting coral mortality, of bleaching events. In recent literature a correlation has been seen in the power of tropical cyclones and average sea surface temperature, making the study of the effect of TCs on the ecology of reefs an urgent one. We will present case studies where a TCs occurred near bleaching episodes and a statistical analysis to quantify this effect. To do this we use historical cyclone track data, satellite SST data, and a dataset of reefs. But there are other TC effects on reefs that bear investigation. Because TCs occur near corals that experience thermal stress, the changes in the corals environment caused by TCs might be anomalously detrimental. For example, data suggests that corals, because they are stressed by increased sedimentation, are more vulnerable to disease and algal overgrowth after TC damage. Nutrients have been shown to increase the severity of coral diseases. With satellite data it can be shown that short-term events such as increased run-off due to tropical cyclones can be an important part of the distribution of pollutants and pathogens affecting reefs. Infectious diseases severely affect

  4. Bacteria are not the primary cause of bleaching in the Mediterranean coral Oculina patagonica.

    PubMed

    Ainsworth, T D; Fine, M; Roff, G; Hoegh-Guldberg, O

    2008-01-01

    Coral bleaching occurs when the endosymbiosis between corals and their symbionts disintegrates during stress. Mass coral bleaching events have increased over the past 20 years and are directly correlated with periods of warm sea temperatures. However, some hypotheses have suggested that reef-building corals bleach due to infection by bacterial pathogens. The 'Bacterial Bleaching' hypothesis is based on laboratory studies of the Mediterranean invading coral, Oculina patagonica, and has further generated conclusions such as the coral probiotic hypothesis and coral hologenome theory of evolution. We aimed to investigate the natural microbial ecology of O. patagonica during the annual bleaching using fluorescence in situ hybridization to map bacterial populations within the coral tissue layers, and found that the coral bleaches on the temperate rocky reefs of the Israeli coastline without the presence of Vibrio shiloi or bacterial penetration of its tissue layers. Bacterial communities were found associated with the endolithic layer of bleached coral regions, and a community dominance shift from an apparent cyanobacterial-dominated endolithic layer to an algal-dominated layer was found in bleached coral samples. While bacterial communities certainly play important roles in coral stasis and health, we suggest environmental stressors, such as those documented with reef-building corals, are the primary triggers leading to bleaching of O. patagonica and suggest that bacterial involvement in patterns of bleaching is that of opportunistic colonization.

  5. Sunscreens Cause Coral Bleaching by Promoting Viral Infections

    PubMed Central

    Danovaro, Roberto; Bongiorni, Lucia; Corinaldesi, Cinzia; Giovannelli, Donato; Damiani, Elisabetta; Astolfi, Paola; Greci, Lucedio; Pusceddu, Antonio

    2008-01-01

    Background Coral bleaching (i.e., the release of coral symbiotic zooxanthellae) has negative impacts on biodiversity and functioning of reef ecosystems and their production of goods and services. This increasing world-wide phenomenon is associated with temperature anomalies, high irradiance, pollution, and bacterial diseases. Recently, it has been demonstrated that personal care products, including sunscreens, have an impact on aquatic organisms similar to that of other contaminants. Objectives Our goal was to evaluate the potential impact of sunscreen ingredients on hard corals and their symbiotic algae. Methods In situ and laboratory experiments were conducted in several tropical regions (the Atlantic, Indian, and Pacific Oceans, and the Red Sea) by supplementing coral branches with aliquots of sunscreens and common ultraviolet filters contained in sunscreen formula. Zooxanthellae were checked for viral infection by epifluorescence and transmission electron microscopy analyses. Results Sunscreens cause the rapid and complete bleaching of hard corals, even at extremely low concentrations. The effect of sunscreens is due to organic ultraviolet filters, which are able to induce the lytic viral cycle in symbiotic zooxanthellae with latent infections. Conclusions We conclude that sunscreens, by promoting viral infection, potentially play an important role in coral bleaching in areas prone to high levels of recreational use by humans. PMID:18414624

  6. Annual coral bleaching and the long-term recovery capacity of coral.

    PubMed

    Schoepf, Verena; Grottoli, Andréa G; Levas, Stephen J; Aschaffenburg, Matthew D; Baumann, Justin H; Matsui, Yohei; Warner, Mark E

    2015-11-22

    Mass bleaching events are predicted to occur annually later this century. Nevertheless, it remains unknown whether corals will be able to recover between annual bleaching events. Using a combined tank and field experiment, we simulated annual bleaching by exposing three Caribbean coral species (Porites divaricata, Porites astreoides and Orbicella faveolata) to elevated temperatures for 2.5 weeks in 2 consecutive years. The impact of annual bleaching stress on chlorophyll a, energy reserves, calcification, and tissue C and N isotopes was assessed immediately after the second bleaching and after both short- and long-term recovery on the reef (1.5 and 11 months, respectively). While P. divaricata and O. faveolata were able to recover from repeat bleaching within 1 year, P. astreoides experienced cumulative damage that prevented full recovery within this time frame, suggesting that repeat bleaching had diminished its recovery capacity. Specifically, P. astreoides was not able to recover protein and carbohydrate concentrations. As energy reserves promote bleaching resistance, failure to recover from annual bleaching within 1 year will likely result in the future demise of heat-sensitive coral species.

  7. Annual coral bleaching and the long-term recovery capacity of coral

    PubMed Central

    Schoepf, Verena; Grottoli, Andréa G.; Levas, Stephen J.; Aschaffenburg, Matthew D.; Baumann, Justin H.; Matsui, Yohei; Warner, Mark E.

    2015-01-01

    Mass bleaching events are predicted to occur annually later this century. Nevertheless, it remains unknown whether corals will be able to recover between annual bleaching events. Using a combined tank and field experiment, we simulated annual bleaching by exposing three Caribbean coral species (Porites divaricata, Porites astreoides and Orbicella faveolata) to elevated temperatures for 2.5 weeks in 2 consecutive years. The impact of annual bleaching stress on chlorophyll a, energy reserves, calcification, and tissue C and N isotopes was assessed immediately after the second bleaching and after both short- and long-term recovery on the reef (1.5 and 11 months, respectively). While P. divaricata and O. faveolata were able to recover from repeat bleaching within 1 year, P. astreoides experienced cumulative damage that prevented full recovery within this time frame, suggesting that repeat bleaching had diminished its recovery capacity. Specifically, P. astreoides was not able to recover protein and carbohydrate concentrations. As energy reserves promote bleaching resistance, failure to recover from annual bleaching within 1 year will likely result in the future demise of heat-sensitive coral species. PMID:26582020

  8. A method to objectively optimize coral bleaching prediction techniques

    NASA Astrophysics Data System (ADS)

    van Hooidonk, R. J.; Huber, M.

    2007-12-01

    Thermally induced coral bleaching is a global threat to coral reef health. Methodologies, e.g. the Degree Heating Week technique, have been developed to predict bleaching induced by thermal stress by utilizing remotely sensed sea surface temperature (SST) observations. These techniques can be used as a management tool for Marine Protected Areas (MPA). Predictions are valuable to decision makers and stakeholders on weekly to monthly time scales and can be employed to build public awareness and support for mitigation. The bleaching problem is only expected to worsen because global warming poses a major threat to coral reef health. Indeed, predictive bleaching methods combined with climate model output have been used to forecast the global demise of coral reef ecosystems within coming decades due to climate change. Accuracy of these predictive techniques has not been quantitatively characterized despite the critical role they play. Assessments have typically been limited, qualitative or anecdotal, or more frequently they are simply unpublished. Quantitative accuracy assessment, using well established methods and skill scores often used in meteorology and medical sciences, will enable objective optimization of existing predictive techniques. To accomplish this, we will use existing remotely sensed data sets of sea surface temperature (AVHRR and TMI), and predictive values from techniques such as the Degree Heating Week method. We will compare these predictive values with observations of coral reef health and calculate applicable skill scores (Peirce Skill Score, Hit Rate and False Alarm Rate). We will (a) quantitatively evaluate the accuracy of existing coral reef bleaching predictive methods against state-of- the-art reef health databases, and (b) present a technique that will objectively optimize the predictive method for any given location. We will illustrate this optimization technique for reefs located in Puerto Rico and the US Virgin Islands.

  9. INDICATORS OF UV EXPOSURE IN CORALS: RELEVANCE TO GLOBAL CLIMATE CHANGE AND CORAL BLEACHING

    EPA Science Inventory

    Increased exposure to solar UV radiation and elevated water temperatures are believed to play a role in the bleaching of corals. To provide additional tools for evaluating the role of UV radiation, we have examined UV-specific effects in coral and have characterized factors that ...

  10. RESISTANCE AND RESILIENCE TO CORAL BLEACHING: IMPLICATIONS FOR CORAL REEF CONSERVATION AND MANAGEMENT

    EPA Science Inventory

    The massive scale of the 1997-1998 El Nino-associated coral bleaching event underscores the need for strategies to mitigate biodiversity losses resulting from temperature-induced coral mortality. As baseline sea surface temperatures continue to rise, climate change may represent ...

  11. Characterization of fatty acid composition in healthy and bleached corals from Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Bachok, Zainudin; Mfilinge, Prosper; Tsuchiya, Makoto

    2006-11-01

    Under bleaching conditions, corals lose their symbiotic zooxanthellae, and thus, the ability to synthesize fatty acids (FAs) from photosynthetically derived carbon. This study investigated the lipid content and FA composition in healthy and bleached corals from the Odo reef flat in Okinawa, southern Japan, following a bleaching event. It was hypothesized that the FA composition and abundance would change as algae are lost or die, and possibly microbial abundance would increase in corals as a consequence of bleaching. The lipid content and FA composition of three healthy coral species ( Pavona frondifera, Acropora pulchra, and Goniastrea aspera) and of partially bleached and completely bleached colonies of P. frondifera were examined. The FA composition did not differ among healthy corals, but differed significantly among healthy, partially bleached, and completely bleached specimens of P. frondifera. Completely bleached corals contained significantly lower lipid and total FA content, as well as lower relative amounts of polyunsaturated FAs and higher relative amounts of saturated FAs, than healthy and partially bleached corals. Furthermore, there was a significantly higher relative concentration of monounsaturated FAs and odd-numbered branched FAs in completely bleached corals, indicating an increase in bacterial colonization in the bleached corals.

  12. Coral bleaching and habitat effects on colonisation of reef fish assemblages: An experimental study

    NASA Astrophysics Data System (ADS)

    Yahya, Saleh A. S.; Gullström, Martin; Öhman, Marcus C.; Jiddawi, Narriman S.; Andersson, Mathias H.; Mgaya, Yunus D.; Lindahl, Ulf

    2011-07-01

    Degradation and mortality of corals is increasing worldwide and is expected to have significant effects on coral reef fish; hence studies on these effects are essential. In the present study, a field experiment was set up within Mafia Island Marine Park in Tanzania (East Africa) to examine the effects of bleaching and habitat structure on colonisation of coral reef fish assemblages. Live and bleached staghorn coral Acropora formosa was transplanted onto plots in a site dominated by sand and rubble, and the experimental design comprised of three treatments: live coral, bleached coral and eroded coral rubble. There was an immediate increase (within 24 h) in fish abundance and diversity in the two treatments with standing corals. Overall, live and bleached coral plots showed similar effects, but differed from the eroded coral plots which had a much lower abundance and diversity of fish. In general, fish species diversity changed with time over the study period while fish abundance did not. Multivariate analyses showed that while there were differences in fish assemblage structure between standing corals and the eroded coral treatment, there was neither a difference between live and bleached coral treatments nor any temporal effects on fish assemblage structure. Our findings suggest that physical structure and complexity of habitat have stronger effects on colonisation of reef fish assemblages than changes in coral health (such as bleaching) which do not affect coral structure. This may have important implications for appropriate coral reef management.

  13. Anthropogenic mortality on coral reefs in Caribbean Panama predates coral disease and bleaching.

    PubMed

    Cramer, Katie L; Jackson, Jeremy B C; Angioletti, Christopher V; Leonard-Pingel, Jill; Guilderson, Thomas P

    2012-06-01

    Caribbean reef corals have declined precipitously since the 1980s due to regional episodes of bleaching, disease and algal overgrowth, but the extent of earlier degradation due to localised historical disturbances such as land clearing and overfishing remains unresolved. We analysed coral and molluscan fossil assemblages from reefs near Bocas del Toro, Panama to construct a timeline of ecological change from the 19th century-present. We report large changes before 1960 in coastal lagoons coincident with extensive deforestation, and after 1960 on offshore reefs. Striking changes include the demise of previously dominant staghorn coral Acropora cervicornis and oyster Dendrostrea frons that lives attached to gorgonians and staghorn corals. Reductions in bivalve size and simplification of gastropod trophic structure further implicate increasing environmental stress on reefs. Our paleoecological data strongly support the hypothesis, from extensive qualitative data, that Caribbean reef degradation predates coral bleaching and disease outbreaks linked to anthropogenic climate change.

  14. High spatial variability in coral bleaching around Moorea (French Polynesia): patterns across locations and water depths.

    PubMed

    Penin, Lucie; Adjeroud, Mehdi; Schrimm, Muriel; Lenihan, Hunter Stanton

    2007-02-01

    Mass coral bleaching events are one of the main threats to coral reefs. A severe bleaching event impacted Moorea, French Polynesia, between March and July 2002, causing 55+/-14% of colonies to suffer bleaching around the island. However, bleaching varied significantly across coral genera, locations, and as a function of water depth, with a bleaching level as high as 72% at some stations. Corals in deeper water bleached at a higher rate than those in shallow water, and the north coast was more impacted than the west coast. The relatively small scale of variability in bleaching responses probably resulted from the interaction between extrinsic factors, including hydrodynamic condition, and intrinsic factors, such as differential adaptation of the coral/algal association.

  15. Bleaching in reef corals: Physiological and stable isotopic responses

    PubMed Central

    Porter, James W.; Fitt, William K.; Spero, Howard J.; Rogers, Caroline S.; White, Michael W.

    1989-01-01

    During the late summer to fall of 1987, Caribbean reef corals experienced an intense and widespread discoloration event described as bleaching. Contrary to initial predictions, most bleached corals did not die. However, energy input from zooxanthellae decreased, as estimated from: (i) δ13C values, a measure of the discrimination against 13C in 12C/13C assimilation, of skeletal aragonite; (ii) in situ photosynthesis-irradiance measurements; (iii) and tissue biomass parameters of Montastraea annularis and Agaricia lamarcki. The δ18O signal, a measure of the discrimination against 18O in 16O/18O assimilation, from M. annularis skeletons demonstrated that this event coincided with abnormally elevated water temperatures. Images PMID:16594090

  16. Tropical cyclone cooling combats region-wide coral bleaching.

    PubMed

    Carrigan, Adam D; Puotinen, Marji

    2014-05-01

    Coral bleaching has become more frequent and widespread as a result of rising sea surface temperature (SST). During a regional scale SST anomaly, reef exposure to thermal stress is patchy in part due to physical factors that reduce SST to provide thermal refuge. Tropical cyclones (TCs - hurricanes, typhoons) can induce temperature drops at spatial scales comparable to that of the SST anomaly itself. Such cyclone cooling can mitigate bleaching across broad areas when well-timed and appropriately located, yet the spatial and temporal prevalence of this phenomenon has not been quantified. Here, satellite SST and historical TC data are used to reconstruct cool wakes (n=46) across the Caribbean during two active TC seasons (2005 and 2010) where high thermal stress was widespread. Upon comparison of these datasets with thermal stress data from Coral Reef Watch and published accounts of bleaching, it is evident that TC cooling reduced thermal stress at a region-wide scale. The results show that during a mass bleaching event, TC cooling reduced thermal stress below critical levels to potentially mitigate bleaching at some reefs, and interrupted natural warming cycles to slow the build-up of thermal stress at others. Furthermore, reconstructed TC wave damage zones suggest that it was rare for more reef area to be damaged by waves than was cooled (only 12% of TCs). Extending the time series back to 1985 (n = 314), we estimate that for the recent period of enhanced TC activity (1995-2010), the annual probability that cooling and thermal stress co-occur is as high as 31% at some reefs. Quantifying such probabilities across the other tropical regions where both coral reefs and TCs exist is vital for improving our understanding of how reef exposure to rising SSTs may vary, and contributes to a basis for targeting reef conservation.

  17. Prediction of Coral Bleaching in the Florida Keys Using Remotely Sensed Data

    EPA Science Inventory

    Coral bleaching has been attributed to extremes or stressful synergy in several physical variables of the coral habitat. Of particular concern have been temperature, ultraviolet radiation, and photosynthetically available radiation. Satellite observing systems allow synoptic-sca...

  18. INDICATORS OF UV EXPOSURE IN CORALS AND THEIR RELEVANCE TO GLOBAL CLIMATE CHANGE AND CORAL BLEACHING. (R826939)

    EPA Science Inventory

    A compelling aspect of the deterioration of coral reefs is the phenomenon of coral bleaching. Through interactions with other factors such as sedimentation, pollution, and bacterial infection, bleaching can impact large areas of a reef with limited recovery, and it might be in...

  19. Excess algal symbionts increase the susceptibility of reef corals to bleaching

    NASA Astrophysics Data System (ADS)

    Cunning, Ross; Baker, Andrew C.

    2013-03-01

    Rising ocean temperatures associated with global climate change are causing mass coral bleaching and mortality worldwide. Understanding the genetic and environmental factors that mitigate coral bleaching susceptibility may aid local management efforts to help coral reefs survive climate change. Although bleaching susceptibility depends partly on the genetic identity of a coral's algal symbionts, the effect of symbiont density, and the factors controlling it, remain poorly understood. By applying a new metric of symbiont density to study the coral Pocillopora damicornis during seasonal warming and acute bleaching, we show that symbiont cell ratio density is a function of both symbiont type and environmental conditions, and that corals with high densities are more susceptible to bleaching. Higher vulnerability of corals with more symbionts establishes a quantitative mechanistic link between symbiont density and the molecular basis for coral bleaching, and indicates that high densities do not buffer corals from thermal stress, as has been previously suggested. These results indicate that environmental conditions that increase symbiont densities, such as nutrient pollution, will exacerbate climate-change-induced coral bleaching, providing a mechanistic explanation for why local management to reduce these stressors will help coral reefs survive future warming.

  20. Forecasting decadal changes in sea surface temperatures and coral bleaching within a Caribbean coral reef

    NASA Astrophysics Data System (ADS)

    Li, Angang; Reidenbach, Matthew A.

    2014-09-01

    Elevated sea surface temperature (SST) caused by global warming is one of the major threats to coral reefs. While increased SST has been shown to negatively affect the health of coral reefs by increasing rates of coral bleaching, how changes to atmospheric heating impact SST distributions, modified by local flow environments, has been less understood. This study aimed to simulate future water flow patterns and water surface heating in response to increased air temperature within a coral reef system in Bocas del Toro, Panama, located within the Caribbean Sea. Water flow and SST were modeled using the Delft3D-FLOWcomputer simulation package. Locally measured physical parameters, including bathymetry, astronomic tidal forcing, and coral habitat distribution were input into the model and water flow, and SST was simulated over a four-month period under present day, as well as projected warming scenarios in 2020s, 2050s, and 2080s. Changes in SST, and hence the thermal stress to corals, were quantified by degree heating weeks. Results showed that present-day reported bleaching sites were consistent with localized regions of continuous high SST. Regions with highest SST were located within shallow coastal sites adjacent to the mainland or within the interior of the bay, and characterized by low currents with high water retention times. Under projected increases in SSTs, shallow reef areas in low flow regions were found to be hot spots for future bleaching.

  1. Hurricanes and coral bleaching linked to changes in coral recruitment in Tobago.

    PubMed

    Mallela, J; Crabbe, M J C

    2009-10-01

    Knowledge of coral recruitment patterns helps us understand how reefs react following major disturbances and provides us with an early warning system for predicting future reef health problems. We have reconstructed and interpreted historical and modern-day recruitment patterns, using a combination of growth modelling and in situ recruitment experiments, in order to understand how hurricanes, storms and bleaching events have influenced coral recruitment on the Caribbean coastline of Tobago. Whilst Tobago does not lie within the main hurricane belt results indicate that regional hurricane events negatively impact coral recruitment patterns in the Southern Caribbean. In years following hurricanes, tropical storms and bleaching events, coral recruitment was reduced when compared to normal years (p=0.016). Following Hurricane Ivan in 2004 and the 2005-2006 bleaching event, coral recruitment was markedly limited with only 2% (n=6) of colonies estimated to have recruited during 2006 and 2007. Our experimental results indicate that despite multiple large-scale disturbances corals are still recruiting on Tobago's marginal reef systems, albeit in low numbers.

  2. Differential Response of Coral Assemblages to Thermal Stress Underscores the Complexity in Predicting Bleaching Susceptibility.

    PubMed

    Chou, Loke Ming; Toh, Tai Chong; Toh, Kok Ben; Ng, Chin Soon Lionel; Cabaitan, Patrick; Tun, Karenne; Goh, Eugene; Afiq-Rosli, Lutfi; Taira, Daisuke; Du, Rosa Celia Poquita; Loke, Hai Xin; Khalis, Aizat; Li, Jinghan; Song, Tiancheng

    2016-01-01

    Coral bleaching events have been predicted to occur more frequently in the coming decades with global warming. The susceptibility of corals to bleaching during thermal stress episodes is dependent on many factors and an understanding of these underlying drivers is crucial for conservation management. In 2013, a mild bleaching episode ensued in response to elevated sea temperature on the sediment-burdened reefs in Singapore. Surveys of seven sites highlighted variable bleaching susceptibility among coral genera-Pachyseris and Podabacia were the most impacted (31% of colonies of both genera bleached). The most susceptible genera such as Acropora and Pocillopora, which were expected to bleach, did not. Susceptibility varied between less than 6% and more than 11% of the corals bleached, at four and three sites respectively. Analysis of four of the most bleached genera revealed that a statistical model that included a combination of the factors (genus, colony size and site) provided a better explanation of the observed bleaching patterns than any single factor alone. This underscored the complexity in predicting the coral susceptibility to future thermal stress events and the importance of monitoring coral bleaching episodes to facilitate more effective management of coral reefs under climate change.

  3. Differential Response of Coral Assemblages to Thermal Stress Underscores the Complexity in Predicting Bleaching Susceptibility

    PubMed Central

    Toh, Kok Ben; Ng, Chin Soon Lionel; Cabaitan, Patrick; Tun, Karenne; Goh, Eugene; Afiq-Rosli, Lutfi; Taira, Daisuke; Du, Rosa Celia Poquita; Loke, Hai Xin; Khalis, Aizat; Li, Jinghan; Song, Tiancheng

    2016-01-01

    Coral bleaching events have been predicted to occur more frequently in the coming decades with global warming. The susceptibility of corals to bleaching during thermal stress episodes is dependent on many factors and an understanding of these underlying drivers is crucial for conservation management. In 2013, a mild bleaching episode ensued in response to elevated sea temperature on the sediment-burdened reefs in Singapore. Surveys of seven sites highlighted variable bleaching susceptibility among coral genera–Pachyseris and Podabacia were the most impacted (31% of colonies of both genera bleached). The most susceptible genera such as Acropora and Pocillopora, which were expected to bleach, did not. Susceptibility varied between less than 6% and more than 11% of the corals bleached, at four and three sites respectively. Analysis of four of the most bleached genera revealed that a statistical model that included a combination of the factors (genus, colony size and site) provided a better explanation of the observed bleaching patterns than any single factor alone. This underscored the complexity in predicting the coral susceptibility to future thermal stress events and the importance of monitoring coral bleaching episodes to facilitate more effective management of coral reefs under climate change. PMID:27438593

  4. Lag effects in the impacts of mass coral bleaching on coral reef fish, fisheries, and ecosystems.

    PubMed

    Graham, Nicholas A J; Wilson, Shaun K; Jennings, Simon; Polunin, Nicholas V C; Robinson, Jan; Bijoux, Jude P; Daw, Tim M

    2007-10-01

    Recent episodes of coral bleaching have led to wide-scale loss of reef corals and raised concerns over the effectiveness of existing conservation and management efforts. The 1998 bleaching event was most severe in the western Indian Ocean, where coral declined by up to 90% in some locations. Using fisheries-independent data, we assessed the long-term impacts of this event on fishery target species in the Seychelles, the overall size structure of the fish assemblage, and the effectiveness of two marine protected areas (MPAs) in protecting fish communities. The biomass of fished species above the size retained in fish traps changed little between 1994 and 2005, indicating no current effect on fishery yields. Biomass remained higher in MPAs, indicating they were effective in protecting fish stocks. Nevertheless, the size structure of the fish communities, as described with size-spectra analysis, changed in both fished areas and MPAs, with a decline in smaller fish (<30 cm) and an increase in larger fish (>45 cm). We believe this represents a time-lag response to a reduction in reef structural complexity brought about because fishes are being lost through natural mortality and fishing, and are not being replaced by juveniles. This effect is expected to be greater in terms of fisheries productivity and, because congruent patterns are observed for herbivores, suggests that MPAs do not offer coral reefs long-term resilience to bleaching events. Corallivores and planktivores declined strikingly in abundance, particularly in MPAs, and this decline was associated with a similar pattern of decline in their preferred corals. We suggest that climate-mediated disturbances, such as coral bleaching, be at the fore of conservation planning for coral reefs.

  5. Symbiophagy as a cellular mechanism for coral bleaching.

    PubMed

    Downs, Craig A; Kramarsky-Winter, Esti; Martinez, Jon; Kushmaro, Ariel; Woodley, Cheryl M; Loya, Yossi; Ostrander, Gary K

    2009-02-01

    Coral bleaching is a major contributor to the global declines of coral reefs. This phenomenon is characterized by the loss of symbiotic algae, their pigments or both. Despite wide scientific interest, the mechanisms by which bleaching occurs are still poorly understood. Here we report that the removal of the symbiont during light and temperature stress is achieved using the host's cellular autophagic-associated machinery. Host cellular and subcellular morphologies showed increased vacuolization and appearance of autophagic membranes surrounding a variety of organelles and surrounding the symbiotic algae. Markers of autophagy (Rab 7 and LAS) corroborate these observations. Results showed that during stress the symbiont vacuolar membrane is transformed from a conduit of nutrient exchange to a digestive organelle resulting in the consumption of the symbiont, a process we term symbiophagy. We posit that during a stress event, the mechanism maintaining symbiosis is destabilized and symbiophagy is activated, ultimately resulting in the phenomenon of bleaching. Symbiophagy may have evolved from a more general primordial innate intracellular protective pathway termed xenophagy.

  6. Chronic nutrient enrichment increases prevalence and severity of coral disease and bleaching.

    PubMed

    Vega Thurber, Rebecca L; Burkepile, Deron E; Fuchs, Corinne; Shantz, Andrew A; McMinds, Ryan; Zaneveld, Jesse R

    2014-02-01

    Nutrient loading is one of the strongest drivers of marine habitat degradation. Yet, the link between nutrients and disease epizootics in marine organisms is often tenuous and supported only by correlative data. Here, we present experimental evidence that chronic nutrient exposure leads to increases in both disease prevalence and severity and coral bleaching in scleractinian corals, the major habitat-forming organisms in tropical reefs. Over 3 years, from June 2009 to June 2012, we continuously exposed areas of a coral reef to elevated levels of nitrogen and phosphorus. At the termination of the enrichment, we surveyed over 1200 scleractinian corals for signs of disease or bleaching. Siderastrea siderea corals within enrichment plots had a twofold increase in both the prevalence and severity of disease compared with corals in unenriched control plots. In addition, elevated nutrient loading increased coral bleaching; Agaricia spp. of corals exposed to nutrients suffered a 3.5-fold increase in bleaching frequency relative to control corals, providing empirical support for a hypothesized link between nutrient loading and bleaching-induced coral declines. However, 1 year later, after nutrient enrichment had been terminated for 10 months, there were no differences in coral disease or coral bleaching prevalence between the previously enriched and control treatments. Given that our experimental enrichments were well within the ranges of ambient nutrient concentrations found on many degraded reefs worldwide, these data provide strong empirical support to the idea that coastal nutrient loading is one of the major factors contributing to the increasing levels of both coral disease and coral bleaching. Yet, these data also suggest that simple improvements to water quality may be an effective way to mitigate some coral disease epizootics and the corresponding loss of coral cover in the future.

  7. Genome analysis of the coral bleaching pathogen Vibrio shiloi.

    PubMed

    Reshef, Leah; Ron, Eliora; Rosenberg, Eugene

    2008-08-01

    The past few decades have seen a world-wide increase in coral diseases, yet little is known about coral pathogens. In this study, techniques commonly used in pathogenomic research were applied to the coral pathogen Vibrio shiloi in order to identify genetic elements involved in its virulence. Suppressive subtractive hybridization was used to compare the gene content of V. shiloi to that of a closely related but non-pathogenic bacterium, Vibrio mediterranei, resulting in identification of several putative virulence factors and of three novel genomic islands. The entire genome of V. shiloi was further screened for genes related to previously characterized steps in infection: adhesion, superoxide dismutase production and toxin production. Exposure of pure cultures of V. shiloi to crushed coral tissues strongly affected the expression of seven genes encoding pili, zona occludins toxin (Zot) and a superoxide dismutase. Analysis of eight V. shiloi strains isolated in the last decade shows a shift of the natural population from strains carrying all three genomic islands to strains carrying none of them. This shift occurred following appearance of resistance in the coral Oculina patagonica to infection by V. shiloi. The relevance of these findings to the bleaching disease caused by V. shiloi is discussed.

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

    PubMed

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

    2008-09-01

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

  9. Changes in coral-associated microbial communities during a bleaching event.

    PubMed

    Bourne, David; Iida, Yuki; Uthicke, Sven; Smith-Keune, Carolyn

    2008-04-01

    Environmental stressors such as increased sea surface temperatures are well-known for contributing to coral bleaching; however, the effect of increased temperatures and subsequent bleaching on coral-associated microbial communities is poorly understood. Colonies of the hard coral Acropora millepora were tagged on a reef flat off Magnetic Island (Great Barrier Reef) and surveyed over 2.5 years, which included a severe bleaching event in January/February 2002. Daily average water temperatures exceeded the previous 10-year average by more than 1 degrees C for extended periods with field-based visual surveys recording all tagged colonies displaying signs of bleaching. During the bleaching period, direct counts of coral zooxanthellae densities decreased by approximately 64%, before recovery to pre-bleaching levels after the thermal stress event. A subset of three tagged coral colonies were sampled through the bleaching event and changes in the microbial community elucidated. Denaturing gradient gel electrophoresis (DGGE) analysis demonstrated conserved bacterial banding profiles between the three coral colonies, confirming previous studies highlighting specific microbial associations. As coral colonies bleached, the microbial community shifted and redundancy analysis (RDA) of DGGE banding patterns revealed a correlation of increasing temperature with the appearance of Vibrio-affiliated sequences. Interestingly, this shift to a Vibrio-dominated community commenced prior to visual signs of bleaching. Clone libraries hybridized with Vibrio-specific oligonucleotide probes confirmed an increase in the fraction of Vibrio-affiliated clones during the bleaching period. Post bleaching, the coral microbial associations again shifted, returning to a profile similar to the fingerprints prior to bleaching. This provided further evidence for corals selecting and shaping their microbial partners. For non-bleached samples, a close association with Spongiobacter-related sequences were

  10. Effects of disturbance on coral communities: bleaching in Moorea, French Polynesia

    NASA Astrophysics Data System (ADS)

    Gleason, M. G.

    1993-11-01

    This study examines patterns of susceptibility and short-term recovery of corals from bleaching. A mass coral bleaching event began in March, 1991 on reefs in Moorea, French Polynesia and affected corals on the shallow barrier reef and to >20 m depth on the outer forereef slope. There were significant differences in the effect of the bleaching among common coral genera, with Acropora, Montastrea, Montipora, and Pocillopora more affected than Porites, Pavona, leptastrea or Millepora. Individual colonies of the common species of Acropora and Pocillopora were marked and their fate assessed on a subsequent survey in August, 1991 to determine rates of recovery and mortality. Ninety-six percent of Acropora spp. showed some degree of bleaching compared to 76% of Pocillopora spp. From March to August mortality of bleached colonies of Pocillopora was 17%, 38% recovered completely, and many suffered some partial mortality of the tissue. In contrast, 63% of the Acropora spp. died, and about 10% recovered completely. Generally, those colonies with less than 50% of the colony area affected by the bleaching recovered at a higher rate than did those with more severe bleaching. Changes in community composition four months after the event began included a significant decrease only in crustose algae and an increase in cover of filamentous algae, much of which occupied plate-like and branching corals that had died in the bleaching event. Total coral cover and cover of susceptible coral genera had declined, but not significantly, after the event.

  11. Short-term coral bleaching is not recorded by skeletal boron isotopes.

    PubMed

    Schoepf, Verena; McCulloch, Malcolm T; Warner, Mark E; Levas, Stephen J; Matsui, Yohei; Aschaffenburg, Matthew D; Grottoli, Andréa G

    2014-01-01

    Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ13C), oxygen (δ18O) isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that reconstruction of

  12. Short-Term Coral Bleaching Is Not Recorded by Skeletal Boron Isotopes

    PubMed Central

    Schoepf, Verena; McCulloch, Malcolm T.; Warner, Mark E.; Levas, Stephen J.; Matsui, Yohei; Aschaffenburg, Matthew D.; Grottoli, Andréa G.

    2014-01-01

    Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ13C), oxygen (δ18O) isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that reconstruction of

  13. Skeletal records of community-level bleaching in Porites corals from Palau

    NASA Astrophysics Data System (ADS)

    Barkley, Hannah C.; Cohen, Anne L.

    2016-12-01

    Tropical Pacific sea surface temperature is projected to rise an additional 2-3 °C by the end of this century, driving an increase in the frequency and intensity of coral bleaching. With significant global coral reef cover already lost due to bleaching-induced mortality, efforts are underway to identify thermally tolerant coral communities that might survive projected warming. Massive, long-lived corals accrete skeletal bands of anomalously high density in response to episodes of thermal stress. These "stress bands" are potentially valuable proxies for thermal tolerance, but to date their application to questions of community bleaching history has been limited. Ecological surveys recorded bleaching of coral communities across the Palau archipelago during the 1998 and 2010 warm events. Between 2011 and 2015, we extracted skeletal cores from living Porites colonies at 10 sites spanning barrier reef and lagoon environments and quantified the proportion of stress bands present in each population during bleaching years. Across Palau, the prevalence of stress bands tracked the severity of thermal stress, with more stress bands occurring in 1998 (degree heating weeks = 13.57 °C-week) than during the less severe 2010 event (degree heating weeks = 4.86 °C-week). Stress band prevalence also varied by reef type, as more corals on the exposed barrier reef formed stress bands than did corals from sheltered lagoon environments. Comparison of Porites stress band prevalence with bleaching survey data revealed a strong correlation between percent community bleaching and the proportion of colonies with stress bands in each year. Conversely, annual calcification rates did not decline consistently during bleaching years nor did annually resolved calcification histories always track interannual variability in temperature. Our data suggest that stress bands in massive corals contain valuable information about spatial and temporal trends in coral reef bleaching and can aid in

  14. Sibling species in Montastraea annularis, coral bleaching, and the coral climate record

    SciTech Connect

    Knowlton, N.; Weil, E.; Weigt, L.A.; Guzman, H.M. )

    1992-01-17

    Measures of growth and skeletal isotopic ratios in the Caribbean coral Montastraea annularis are fundamental to many studies of paleoceanography, environmental degradation, and global climate change. This taxon is shown to consist of at least three sibling species in shallow water. The two most commonly studied of these show highly significant differences in growth rate and oxygen isotopic ratios, parameters routinely used to estimate past climatic conditions; unusual coloration in the third may have confused research on coral bleaching. Interpretation or comparison of past and current studies can be jeopardized by ignoring these species boundaries.

  15. Seasonal Dynamical Prediction of Coral Bleaching in the Great Barrier Reef, Australia

    NASA Astrophysics Data System (ADS)

    Spillman, C. M.; Alves, O.

    2009-05-01

    Sea surface temperature (SST) is now recognised as the primary cause of mass coral bleaching events. Coral bleaching occurs during times of stress, particularly when SSTs exceed the coral colony's tolerance level. Global warming is potentially a serious threat to the future of the world's reef systems with predictions by the international community that bleaching will increase in both frequency and severity. Advance warning of anomalous sea surface temperatures, and thus potential bleaching events, would allow for the implementation of management strategies to minimise reef damage. Seasonal SST forecasts from the coupled ocean-atmosphere model POAMA (Bureau of Meteorology) have skill in the Great Barrier Reef (Australia) several months into the future. We will present model forecasts and probabilistic products for use in reef management, and assess model skill in the region. These products will revolutionise the way in which coral bleaching events are monitored and assessed in the Great Barrier Reef and Australian region.

  16. Climate change disables coral bleaching protection on the Great Barrier Reef.

    PubMed

    Ainsworth, Tracy D; Heron, Scott F; Ortiz, Juan Carlos; Mumby, Peter J; Grech, Alana; Ogawa, Daisie; Eakin, C Mark; Leggat, William

    2016-04-15

    Coral bleaching events threaten the sustainability of the Great Barrier Reef (GBR). Here we show that bleaching events of the past three decades have been mitigated by induced thermal tolerance of reef-building corals, and this protective mechanism is likely to be lost under near-future climate change scenarios. We show that 75% of past thermal stress events have been characterized by a temperature trajectory that subjects corals to a protective, sub-bleaching stress, before reaching temperatures that cause bleaching. Such conditions confer thermal tolerance, decreasing coral cell mortality and symbiont loss during bleaching by over 50%. We find that near-future increases in local temperature of as little as 0.5°C result in this protective mechanism being lost, which may increase the rate of degradation of the GBR.

  17. SHEDDING LIGHT ON CORALS HEALTH: INTERACTIONS OF CLIMATE CHANGE AND SOLAR RADIATION WITH BLEACHING

    EPA Science Inventory

    Coral bleaching and declines in coral reef health in recent years have been attributed in part to processes driven by UV and/or visible light. For coral assemblages, exposure to UV light is often an unavoidable consequence of having access to visible (photosynthetically active) ...

  18. Response of coral assemblages to thermal stress: are bleaching intensity and spatial patterns consistent between events?

    PubMed

    Penin, Lucie; Vidal-Dupiol, Jeremie; Adjeroud, Mehdi

    2013-06-01

    Mass bleaching events resulting in coral mortality are among the greatest threats to coral reefs, and are projected to increase in frequency and intensity with global warming. Achieving a better understanding of the consistency of the response of coral assemblages to thermal stress, both spatially and temporally, is essential to determine which reefs are more able to tolerate climate change. We compared variations in spatial and taxonomic patterns between two bleaching events at the scale of an island (Moorea Island, French Polynesia). Despite similar thermal stress and light conditions, bleaching intensity was significantly lower in 2007 (approximately 37 % of colonies showed signs of bleaching) than in 2002, when 55 % of the colonies bleached. Variations in the spatial patterns of bleaching intensity were consistent between the two events. Among nine sampling stations at three locations and three depths, the stations at which the bleaching response was lowest in 2002 were those that showed the lowest levels of bleaching in 2007. The taxonomic patterns of susceptibility to bleaching were also consistent between the two events. These findings have important implications for conservation because they indicate that corals are capable of acclimatization and/or adaptation and that, even at small spatial scales, some areas are consistently more susceptible to bleaching than others.

  19. Susceptibility of central Red Sea corals during a major bleaching event

    NASA Astrophysics Data System (ADS)

    Furby, K. A.; Bouwmeester, J.; Berumen, M. L.

    2013-06-01

    A major coral bleaching event occurred in the central Red Sea near Thuwal, Saudi Arabia, in the summer of 2010, when the region experienced up to 10-11 degree heating weeks. We documented the susceptibility of various coral taxa to bleaching at eight reefs during the peak of this thermal stress. Oculinids and agaricids were most susceptible to bleaching, with up to 100 and 80 % of colonies of these families, respectively, bleaching at some reefs. In contrast, some families, such as mussids, pocilloporids, and pectinids showed low levels of bleaching (<20 % on average). We resurveyed the reefs 7 months later to estimate subsequent mortality. Mortality was highly variable among taxa, with some taxa showing evidence of full recovery and some (e.g., acroporids) apparently suffering nearly complete mortality. The unequal mortality among families resulted in significant change in community composition following the bleaching. Significant factors in the likelihood of coral bleaching during this event were depth of the reef and distance of the reef from shore. Shallow reefs and inshore reefs had a higher prevalence of bleaching. This bleaching event shows that Red Sea reefs are subject to the same increasing pressures that reefs face worldwide. This study provides a quantitative, genus-level assessment of the vulnerability of various coral groups from within the Red Sea to bleaching and estimates subsequent mortality. As such, it can provide valuable insights into the future for reef communities in the Red Sea.

  20. Validation of degree heating weeks as a coral bleaching index in the northwestern Pacific

    NASA Astrophysics Data System (ADS)

    Kayanne, Hajime

    2017-03-01

    Mass bleaching is the most significant threat to coral reefs. The United States National Oceanic and Atmospheric Administration monitors world sea surface temperature (SST) and releases warnings for bleaching based on degree heating weeks (DHW), which is the accumulation of temperature anomalies exceeding the monthly maximum mean SST for a given region. DHW values >4.0 °C-weeks are thought to induce bleaching, and those >8.0 °C-weeks are thought to result in widespread bleaching and some mortality. This study validates the effectiveness of DHW as a mass bleaching index by on-site historical observation at eight sites in the northwestern Pacific Ocean. The mass bleaching events occurred during different years at different sites. The recorded years of the bleaching events matched well with DHW values >8 °C-weeks, and the logistically projected probability of bleaching against DHW showed a positive relationship. DHW provides a reasonable threshold for bleaching.

  1. Trace metal anomalies in bleached Porites coral at Meiji Reef, tropical South China Sea

    NASA Astrophysics Data System (ADS)

    Li, Shu; Yu, Kefu; Zhao, Jianxin; Feng, Yuexing; Chen, Tianran

    2017-01-01

    Coral bleaching has generally been recognized as the main reason for tropical coral reef degradation, but there are few long-term records of coral bleaching events. In this study, trace metals including chromium (Cr), copper (Cu), molybdenum (Mo), manganese (Mn), lead (Pb), tin (Sn), titanium (Ti), vanadium (V), and yttrium (Y), were analyzed in two Porites corals collected from Meiji Reef in the tropical South China Sea (SCS) to assess differences in trace metal concentrations in bleached compared with unbleached coral growth bands. Ti, V, Cr, and Mo generally showed irregular fluctuations in both corals. Bleached layers contained high concentrations of Mn, Cu, Sn, and Pb. Unbleached layers showed moderately high concentrations of Mn and Cu only. The different distribution of trace metals in Porites may be attributable to different selectivity on the basis of vital utility or toxicity. Ti, V, Cr, and Mo are discriminated against by both coral polyps and zooxanthellae, but Mn, Cu, Sn, and Pb are accumulated by zooxanthellae and only Mn and Cu are accumulated by polyps as essential elements. The marked increase in Cu, Mn, Pb, and Sn are associated with bleaching processes, including mucus secretion, tissue retraction, and zooxanthellae expulsion and occlusion. Variation in these trace elements within the coral skeleton can be used as potential tracers of short-lived bleaching events.

  2. Outbreak and persistence of opportunistic symbiotic dinoflagellates during the 2005 Caribbean mass coral 'bleaching' event.

    PubMed

    LaJeunesse, Todd C; Smith, Robin T; Finney, Jennifer; Oxenford, Hazel

    2009-12-07

    Reef corals are sentinels for the adverse effects of rapid global warming on the planet's ecosystems. Warming sea surface temperatures have led to frequent episodes of bleaching and mortality among corals that depend on endosymbiotic micro-algae (Symbiodinium) for their survival. However, our understanding of the ecological and evolutionary response of corals to episodes of thermal stress remains inadequate. For the first time, we describe how the symbioses of major reef-building species in the Caribbean respond to severe thermal stress before, during and after a severe bleaching event. Evidence suggests that background populations of Symbiodinium trenchi (D1a) increased in prevalence and abundance, especially among corals that exhibited high sensitivity to stress. Contrary to previous hypotheses, which posit that a change in symbiont occurs subsequent to bleaching, S. trenchi increased in the weeks leading up to and during the bleaching episode and disproportionately dominated colonies that did not bleach. During the bleaching event, approximately 20 per cent of colonies surveyed harboured this symbiont at high densities (calculated at less than 1.0% only months before bleaching began). However, competitive displacement by homologous symbionts significantly reduced S. trenchi's prevalence and dominance among colonies after a 2-year period following the bleaching event. While the extended duration of thermal stress in 2005 provided an ecological opportunity for a rare host-generalist symbiont, it remains unclear to what extent the rise and fall of S. trenchi was of ecological benefit or whether its increased prevalence was an indicator of weakening coral health.

  3. Seasonal mesophotic coral bleaching of Stylophora pistillata in the Northern Red Sea.

    PubMed

    Nir, Orit; Gruber, David F; Shemesh, Eli; Glasser, Eliezra; Tchernov, Dan

    2014-01-01

    Coral bleaching occurs when environmental stress induces breakdown of the coral-algae symbiosis and the host initiates algae expulsion. Two types of coral bleaching had been thoroughly discussed in the scientific literature; the first is primarily associated with mass coral bleaching events; the second is a seasonal loss of algae and/or pigments. Here, we describe a phenomenon that has been witnessed for repeated summers in the mesophotic zone (40-63 m) in the northern Red Sea: seasonal bleaching and recovery of several hermatypic coral species. In this study, we followed the recurring bleaching process of the common coral Stylophora pistillata. Bleaching occurred from April to September with a 66% decline in chlorophyll a concentration, while recovery began in October. Using aquarium and transplantation experiments, we explored environmental factors such as temperature, photon flux density and heterotrophic food availability. Our experiments and observations did not yield one single factor, alone, responsible for the seasonal bleaching. The dinoflagellate symbionts (of the genus Symbiodinium) in shallow (5 m) Stylophora pistillata were found to have a net photosynthetic rate of 56.98-92.19 µmol O2 cm(-2) day(-1). However, those from mesophotic depth (60 m) during months when they are not bleached are net consumers of oxygen having a net photosynthetic rate between -12.86 - (-10.24) µmol O2 cm(-2) day(-1). But during months when these mesophotic corals are partially-bleached, they yielded higher net production, between -2.83-0.76 µmol O2 cm(-2) day(-1). This study opens research questions as to why mesophotic zooxanthellae are more successfully meeting the corals metabolic requirements when Chl a concentration decreases by over 60% during summer and early fall.

  4. Effects of modeled tropical sea surface temperature variability on coral reef bleaching predictions

    NASA Astrophysics Data System (ADS)

    Van Hooidonk, R. J.

    2011-12-01

    Future widespread coral bleaching and subsequent mortality has been projected with sea surface temperature (SST) data from global, coupled ocean-atmosphere general circulation models (GCMs). While these models possess fidelity in reproducing many aspects of climate, they vary in their ability to correctly capture such parameters as the tropical ocean seasonal cycle and El Niño Southern Oscillation (ENSO) variability. These model weaknesses likely reduce the skill of coral bleaching predictions, but little attention has been paid to the important issue of understanding potential errors and biases, the interaction of these biases with trends and their propagation in predictions. To analyze the relative importance of various types of model errors and biases on coral reef bleaching predictive skill, various intra- and inter-annual frequency bands of observed SSTs were replaced with those frequencies from GCMs 20th century simulations to be included in the Intergovernmental Panel on Climate Change (IPCC) 5th assessment report. Subsequent thermal stress was calculated and predictions of bleaching were made. These predictions were compared with observations of coral bleaching in the period 1982-2007 to calculate skill using an objective measure of forecast quality, the Peirce Skill Score (PSS). This methodology will identify frequency bands that are important to predicting coral bleaching and it will highlight deficiencies in these bands in models. The methodology we describe can be used to improve future climate model derived predictions of coral reef bleaching and it can be used to better characterize the errors and uncertainty in predictions.

  5. Skeletal isotope records of growth perturbations in Porites corals during the 1997-1998 mass bleaching event

    NASA Astrophysics Data System (ADS)

    Suzuki, A.; Gagan, M.; Fabricius, K.; Isdale, P.; Yukino, I.; Kawahata, H.

    2003-04-01

    Severe coral bleaching occurred throughout the tropics in 1997/98. We report skeletal UV fluorescence, oxygen isotope, and carbon isotope evidence for perturbations in coral skeletal growth due to bleaching at Ishigaki Island, Japan, and Pandora Reef, Great Barrier Reef. Bleached corals showed abrupt reductions in skeletal extension rate immediately after summer temperature maxima, indicating that bleaching inhibits coral calcification. A colony growing at the low tide line in Ishigaki exhibited clear blue UV fluorescent bands associated with recurrent growth interruptions. Based on the length of time-gaps observed in the annual isotopic cycle, the typical time required for a coral to recover from bleaching is estimated to be about 5--6 months. The effect of bleaching on the oxygen isotope ratio -- temperature relationship was negligible. However, the Ishigaki corals showed lower carbon isotope ratios during bleaching indicating depressed coral metabolism associated with a reduction in calcification. In contrast, skeletal carbon isotope ratios in the Pandora Reef corals exhibited little change in response to bleaching. This is because the records for Pandora Reef were derived from the shaded sides of coral colonies, where algal photosynthesis was particularly slow prior to bleaching, thus subduing the carbon isotope response to bleaching. Taken together, the isotopic and UV fluorescence signals can be used to reconstruct past bleaching events.

  6. Coral recovery in the central Maldives archipelago since the last major mass-bleaching, in 1998

    NASA Astrophysics Data System (ADS)

    Pisapia, C.; Burn, D.; Yoosuf, R.; Najeeb, A.; Anderson, K. D.; Pratchett, M. S.

    2016-10-01

    Increasing frequency and severity of disturbances is causing global degradation of coral reef ecosystems. This study examined temporal changes in live coral cover and coral composition in the central Maldives from 1997 to 2016, encompassing two bleaching events, a tsunami, and an outbreak of Acanthaster planci. We also examined the contemporary size structure for five dominant coral taxa (tabular Acropora, Acropora muricata, Acropora humilis, Pocillopora spp, and massive Porites). Total coral cover increased throughout the study period, with marked increases following the 1998 mass-bleaching. The relative abundance of key genera has changed through time, where Acropora and Pocillopora (which are highly susceptible to bleaching) were under-represented following 1998 mass-bleaching but increased until outbreaks of A. planci in 2015. The contemporary size-structure for all coral taxa was dominated by larger colonies with peaked distributions suggesting that recent disturbances had a disproportionate impact on smaller colonies, or that recruitment is currently limited. This may suggest that coral resilience has been compromised by recent disturbances, and further bleaching (expected in 2016) could lead to highly protracted recovery times. We showed that Maldivian reefs recovered following the 1998 mass-bleaching event, but it took up to a decade, and ongoing disturbances may be eroding reef resilience.

  7. Coral recovery in the central Maldives archipelago since the last major mass-bleaching, in 1998.

    PubMed

    Pisapia, C; Burn, D; Yoosuf, R; Najeeb, A; Anderson, K D; Pratchett, M S

    2016-10-03

    Increasing frequency and severity of disturbances is causing global degradation of coral reef ecosystems. This study examined temporal changes in live coral cover and coral composition in the central Maldives from 1997 to 2016, encompassing two bleaching events, a tsunami, and an outbreak of Acanthaster planci. We also examined the contemporary size structure for five dominant coral taxa (tabular Acropora, Acropora muricata, Acropora humilis, Pocillopora spp, and massive Porites). Total coral cover increased throughout the study period, with marked increases following the 1998 mass-bleaching. The relative abundance of key genera has changed through time, where Acropora and Pocillopora (which are highly susceptible to bleaching) were under-represented following 1998 mass-bleaching but increased until outbreaks of A. planci in 2015. The contemporary size-structure for all coral taxa was dominated by larger colonies with peaked distributions suggesting that recent disturbances had a disproportionate impact on smaller colonies, or that recruitment is currently limited. This may suggest that coral resilience has been compromised by recent disturbances, and further bleaching (expected in 2016) could lead to highly protracted recovery times. We showed that Maldivian reefs recovered following the 1998 mass-bleaching event, but it took up to a decade, and ongoing disturbances may be eroding reef resilience.

  8. Coral recovery in the central Maldives archipelago since the last major mass-bleaching, in 1998

    PubMed Central

    Pisapia, C.; Burn, D.; Yoosuf, R.; Najeeb, A.; Anderson, K. D.; Pratchett, M. S.

    2016-01-01

    Increasing frequency and severity of disturbances is causing global degradation of coral reef ecosystems. This study examined temporal changes in live coral cover and coral composition in the central Maldives from 1997 to 2016, encompassing two bleaching events, a tsunami, and an outbreak of Acanthaster planci. We also examined the contemporary size structure for five dominant coral taxa (tabular Acropora, Acropora muricata, Acropora humilis, Pocillopora spp, and massive Porites). Total coral cover increased throughout the study period, with marked increases following the 1998 mass-bleaching. The relative abundance of key genera has changed through time, where Acropora and Pocillopora (which are highly susceptible to bleaching) were under-represented following 1998 mass-bleaching but increased until outbreaks of A. planci in 2015. The contemporary size-structure for all coral taxa was dominated by larger colonies with peaked distributions suggesting that recent disturbances had a disproportionate impact on smaller colonies, or that recruitment is currently limited. This may suggest that coral resilience has been compromised by recent disturbances, and further bleaching (expected in 2016) could lead to highly protracted recovery times. We showed that Maldivian reefs recovered following the 1998 mass-bleaching event, but it took up to a decade, and ongoing disturbances may be eroding reef resilience. PMID:27694823

  9. Modelling coral calcification accounting for the impacts of coral bleaching and ocean acidification

    NASA Astrophysics Data System (ADS)

    Evenhuis, C.; Lenton, A.; Cantin, N. E.; Lough, J. M.

    2015-05-01

    Coral reefs are diverse ecosystems that are threatened by rising CO2 levels through increases in sea surface temperature and ocean acidification. Here we present a new unified model that links changes in temperature and carbonate chemistry to coral health. Changes in coral health and population are explicitly modelled by linking rates of growth, recovery and calcification to rates of bleaching and temperature-stress-induced mortality. The model is underpinned by four key principles: the Arrhenius equation, thermal specialisation, correlated up- and down-regulation of traits that are consistent with resource allocation trade-offs, and adaption to local environments. These general relationships allow this model to be constructed from a range of experimental and observational data. The performance of the model is assessed against independent data to demonstrate how it can capture the observed response of corals to stress. We also provide new insights into the factors that determine calcification rates and provide a framework based on well-known biological principles to help understand the observed global distribution of calcification rates. Our results suggest that, despite the implicit complexity of the coral reef environment, a simple model based on temperature, carbonate chemistry and different species can give insights into how corals respond to changes in temperature and ocean acidification.

  10. Modeling coral calcification accounting for the impacts of coral bleaching and ocean acidification

    NASA Astrophysics Data System (ADS)

    Evenhuis, C.; Lenton, A.; Cantin, N. E.; Lough, J. M.

    2014-01-01

    Coral reefs are diverse ecosystems threatened by rising CO2 levels that are driving the observed increases in sea surface temperature and ocean acidification. Here we present a new unified model that links changes in temperature and carbonate chemistry to coral health. Changes in coral health and population are able to explicitly modelled by linking the rates of growth, recovery and calcification to the rates of bleaching and temperature stress induced mortality. The model is underpinned by four key principles: the Arrhenius equation, thermal specialisation, resource allocation trade-offs, and adaption to local environments. These general relationships allow this model to be constructed from a range of experimental and observational data. The different characteristics of this model are also assessed against independent data to show that the model captures the observed response of corals. We also provide new insights into the factors that determine calcification rates and provide a framework based on well-known biological principles for understanding the observed global distribution of calcification rates. Our results suggest that, despite the implicit complexity of the coral reef environment, a simple model based on temperature, carbonate chemistry and different species can reproduce much of the observed response of corals to changes in temperature and ocean acidification.

  11. Can heterotrophic uptake of dissolved organic carbon and zooplankton mitigate carbon budget deficits in annually bleached corals?

    NASA Astrophysics Data System (ADS)

    Levas, Stephen; Grottoli, Andréa G.; Schoepf, Verena; Aschaffenburg, Matthew; Baumann, Justin; Bauer, James E.; Warner, Mark E.

    2016-06-01

    Annual coral bleaching events due to increasing sea surface temperatures are predicted to occur globally by the mid-century and as early as 2025 in the Caribbean, and severely impact coral reefs. We hypothesize that heterotrophic carbon (C) in the form of zooplankton and dissolved organic carbon (DOC) is a significant source of C to bleached corals. Thus, the ability to utilize multiple pools of fixed carbon and/or increase the amount of fixed carbon acquired from one or more pools of fixed carbon (defined here as heterotrophic plasticity) could underlie coral acclimatization and persistence under future ocean-warming scenarios. Here, three species of Caribbean coral— Porites divaricata, P. astreoides, and Orbicella faveolata—were experimentally bleached for 2.5 weeks in two successive years and allowed to recover in the field. Zooplankton feeding was assessed after single and repeat bleaching, while DOC fluxes and the contribution of DOC to the total C budget were determined after single bleaching, 11 months on the reef, and repeat bleaching. Zooplankton was a large C source for P. astreoides, but only following single bleaching. DOC was a source of C for single-bleached corals and accounted for 11-36 % of daily metabolic demand (CHARDOC), but represented a net loss of C in repeat-bleached corals. In repeat-bleached corals, DOC loss exacerbated the negative C budgets in all three species. Thus, the capacity for heterotrophic plasticity in corals is compromised under annual bleaching, and heterotrophic uptake of DOC and zooplankton does not mitigate C budget deficits in annually bleached corals. Overall, these findings suggest that some Caribbean corals may be more susceptible to repeat bleaching than to single bleaching due to a lack of heterotrophic plasticity, and coral persistence under increasing bleaching frequency may ultimately depend on other factors such as energy reserves and symbiont shuffling.

  12. Temperature-regulated bleaching and lysis of the coral Pocillopora damicornis by the novel pathogen Vibrio coralliilyticus.

    PubMed

    Ben-Haim, Yael; Zicherman-Keren, Maya; Rosenberg, Eugene

    2003-07-01

    Coral bleaching is the disruption of symbioses between coral animals and their photosynthetic microalgal endosymbionts (zooxanthellae). It has been suggested that large-scale bleaching episodes are linked to global warming. The data presented here demonstrate that Vibrio coralliilyticus is an etiological agent of bleaching of the coral Pocillopora damicornis. This bacterium was present at high levels in bleached P. damicornis but absent from healthy corals. The bacterium was isolated in pure culture, characterized microbiologically, and shown to cause bleaching when it was inoculated onto healthy corals at 25 degrees C. The pathogen was reisolated from the diseased tissues of the infected corals. The zooxanthella concentration in the bacterium-bleached corals was less than 12% of the zooxanthella concentration in healthy corals. When P. damicornis was infected with V. coralliilyticus at higher temperatures (27 and 29 degrees C), the corals lysed within 2 weeks, indicating that the seawater temperature is a critical environmental parameter in determining the outcome of infection. A large increase in the level of the extracellular protease activity of V. coralliilyticus occurred at the same temperature range (24 to 28 degrees C) as the transition from bleaching to lysis of the corals. We suggest that bleaching of P. damicornis results from an attack on the algae, whereas bacterium-induced lysis and death are promoted by bacterial extracellular proteases. The data presented here support the bacterial hypothesis of coral bleaching.

  13. A study on the recovery of Tobago's coral reefs following the 2010 mass bleaching event.

    PubMed

    Buglass, Salome; Donner, Simon D; Alemu I, Jahson B

    2016-03-15

    In 2010, severe coral bleaching was observed across the southeastern Caribbean, including the island of Tobago, where coral reefs are subject to sedimentation and high nutrient levels from terrestrial runoff. Here we examine changes in corals' colony size distributions over time (2010-2013), juvenile abundances and sedimentation rates for sites across Tobago following the 2010 bleaching event. The results indicated that since pre-bleaching coral cover was already low due to local factors and past disturbance, the 2010 event affected only particular susceptible species' population size structure and increased the proportion of small sized colonies. The low density of juveniles (mean of 5.4±6.3 juveniles/m(-2)) suggests that Tobago's reefs already experienced limited recruitment, especially of large broadcasting species. The juvenile distribution and the response of individual species to the bleaching event support the notion that Caribbean reefs are becoming dominated by weedy non-framework building taxa which are more resilient to disturbances.

  14. Massive bleaching of coral reefs induced by the 2010 ENSO, Puerto Cabello, Venezuela.

    PubMed

    del Mónaco, Carlos; Haiek, Gerard; Narciso, Samuel; Galindo, Miguel

    2012-06-01

    El Niño Southern Oscillation (ENSO) has generated global coral massive bleaching. The aim of this work was to evaluate the massive bleaching of coral reefs in Puerto Cabello, Venezuela derived from ENSO 2010. We evaluated the bleaching of reefs at five localities both at three and five meter depth. The coral cover and densities of colonies were estimated. We recorded living coral cover, number and diameter of bleached and non-bleached colonies of each coral species. The colonies were classified according to the proportion of bleached area. Satellite images (Modis Scar) were analyzed for chlorophyll-a concentration and temperature in August, September, October and November from 2008-2010. Precipitation, wind speed and air temperature information was evaluated in meteorological data for 2009 and 2010. A total of 58.3% of colonies, belonging to 11 hexacoral species, were affected and the greatest responses were observed in Colpophyllia natans, Montastraea annularis and Montastraeafaveolata. The most affected localities were closer to the mainland and had a bleached proportion up to 62.73+/-36.55%, with the highest proportion of affected colonies, whereas the farthest locality showed 20.25+/-14.00% bleached and the smallest proportion. The salinity in situ varied between 30 and 33ppm and high levels of turbidity were observed. According to the satellite images, in 2010 the surface water temperature reached 31 degree C in August, September and October, and resulted higher than those registered in 2008 and 2009. Regionally, chlorophyll values were higher in 2010 than in 2008 and 2009. The meteorological data indicated that precipitation in November 2010 was three times higher than in November 2009. Massive coral bleaching occurred due to a three month period of high temperatures followed by one month of intense ENSO-associated precipitation. However, this latter factor was likely the trigger because of the bleaching gradient observed.

  15. Coral bleaching under unconventional scenarios of climate warming and ocean acidification

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, Lester; Cox, Peter; Halloran, Paul R.; Mumby, Peter J.; Wiltshire, Andy J.

    2015-08-01

    Elevated sea surface temperatures have been shown to cause mass coral bleaching. Widespread bleaching, affecting >90% of global coral reefs and causing coral degradation, has been projected to occur by 2050 under all climate forcing pathways adopted by the IPCC for use within the Fifth Assessment Report. These pathways include an extremely ambitious pathway aimed to limit global mean temperature rise to 2 °C (ref. ; Representative Concentration Pathway 2.6--RCP2.6), which assumes full participation in emissions reductions by all countries, and even the possibility of negative emissions. The conclusions drawn from this body of work, which applied widely used algorithms to estimate coral bleaching, are that we must either accept that the loss of a large percentage of the world’s coral reefs is inevitable, or consider technological solutions to buy those reefs time until atmospheric CO2 concentrations can be reduced. Here we analyse the potential for geoengineering, through stratospheric aerosol-based solar radiation management (SRM), to reduce the extent of global coral bleaching relative to ambitious climate mitigation. Exploring the common criticism of geoengineering--that ocean acidification and its impacts will continue unabated--we focus on the sensitivity of results to the aragonite saturation state dependence of bleaching. We do not, however, address the additional detrimental impacts of ocean acidification on processes such as coral calcification that will further determine the benefit to corals of any SRM-based scenario. Despite the sensitivity of thermal bleaching thresholds to ocean acidification being uncertain, stabilizing radiative forcing at 2020 levels through SRM reduces the risk of global bleaching relative to RCP2.6 under all acidification-bleaching relationships analysed.

  16. Temperature and Light Effects on Extracellular Superoxide Production by Algal and Bacterial Symbionts in Corals: Implications for Coral Bleaching

    NASA Astrophysics Data System (ADS)

    Brighi, C.; Diaz, J. M.; Apprill, A.; Hansel, C. M.

    2014-12-01

    Increased surface seawater temperature due to global warming is one of the main causes of coral bleaching, a phenomenon in which corals lose their photosynthetic algae. Light and temperature induced production of superoxide and other reactive oxygen species (ROS) by these symbiotic algae has been implicated in the breakdown of their symbiotic association with the coral host and subsequent coral bleaching. Nevertheless, a direct link between Symbiodinium ROS production and coral bleaching has not been demonstrated. In fact, given the abundance and diversity of microorganisms within the coral holobiont, the concentration and fluxes of ROS within corals may involve several microbial sources and sinks. Here, we explore the role of increased light and temperature on superoxide production by coral-derived cultures of Symbiodinium algae and Oceanospirillales bacteria of the genus Endozoicomonas, which are globally common and abundant associates of corals. Using a high sensitivity chemiluminescent technique, we find that heat stress (exposure to 34°C vs. 23°C for 2hr or 24hr) has no significant effect on extracellular superoxide production by Symbiodinium isolates within clades B and C, regardless of the level of light exposure. Exposure to high light, however, increased superoxide production by these organisms at both 34°C and 23°C. On the other hand, extracellular superoxide production by Endozoicomonas bacteria tested under the same conditions was stimulated by the combined effects of thermal and light stress. The results of this research suggest that the sources and physical triggers for biological superoxide production within corals are more complex than currently assumed. Thus, further investigations into the biological processes controlling ROS dynamics within corals are required to improve our understanding of the mechanisms underpinning coral bleaching and to aid in the development of mitigation strategies.

  17. Comparing Environmental Influences on Coral Bleaching Across and within Species using Clustered Binomial Regression

    EPA Science Inventory

    Differential susceptibility among reef-building coral species can lead to community shifts and loss of diversity as a result of temperature-induced mass bleaching events. However, the influence of the local environment on species-specific bleaching susceptibilities has not been ...

  18. Coral reef bleaching and sea surface temperature anomalies: 1991-1996 global patterns

    SciTech Connect

    Goreau, T.J.; Hayes, R.L.; Strong, A.

    1997-12-31

    Global spatio-temporal patterns of mass coral reef bleaching during the first half of the 1990s continued to show the strong temperature correlations which first became established in the 1980s. Satellite sea surface temperature data and field observations were used to track thermal bleaching events in real time. Most bleaching events followed warm season sea surface temperature anomalies of around +1 degree celsius above historical means. Global bleaching patterns appear to have been strongly affected by worldwide cooling which followed eruption of Mount Pinatubo in June 1991. High water temperatures and mass coral reef bleaching took place in the Caribbean, Indian Ocean, and South Pacific in 1991, but there were few thermal anomalies or bleaching events in 1992 and 1993, years which were markedly cooler worldwide. Following the settling of Mount Pinatubo aerosols and resumption of global warming trends, extensive ocean thermal hot spots and bleaching events resumed in the South Pacific, South Atlantic, and Indian Oceans in 1994. Bleaching again took place in hot spots in the Indian Ocean and Caribbean in 1995, and in the South Atlantic, Caribbean, South Pacific, North Pacific, and Persian Gulf in 1996. Coral reefs worldwide are now very close to their upper temperature tolerance limits. This sensitivity, and the fact that the warmest ecosystems have no source of immigrant species pre-adapted to warmer conditions, may make coral reef ecosystems the first to be severely impacted if global temperatures and sea levels remain at current values or increase further.

  19. Levels of immunity parameters underpin bleaching and disease susceptibility of reef corals.

    PubMed

    Palmer, Caroline V; Bythell, John C; Willis, Bette L

    2010-06-01

    Immunity is a key life history trait that may explain hierarchies in the susceptibility of corals to disease and thermal bleaching, two of the greatest current threats to coral health and the persistence of tropical reefs. Despite their ongoing and rapid global decline, there have been few investigations into the immunity mechanisms of reef-building corals. Variables commonly associated with invertebrate immunity, including the presence of melanin, size of melanin-containing granular cells, and phenoloxidase (PO) activity, as well as concentrations of fluorescent proteins (FPs), were investigated in hard (Scleractinia) and soft (Alcyonacea) corals spanning 10 families from the Great Barrier Reef. Detectable levels of these indicators were present in all corals investigated, although relative investment differed among coral taxa. Overall levels of investment were inversely correlated to thermal bleaching and disease susceptibility. In addition, PO activity, melanin-containing granular cell size, and FP concentration were each found to be significant predictors of susceptibility and thus may play key roles in coral immunity. Correlative evidence that taxonomic (family-level) variation in the levels of these constituent immunity parameters underpins susceptibility to both thermal bleaching and disease indicates that baseline immunity underlies the vulnerability of corals to these two threats. This reinforces the necessity of a holistic approach to understanding bleaching and disease in order to accurately determine the resilience of coral reefs.

  20. Coral reef recovery status in south Andaman Islands after the bleaching event 2010

    NASA Astrophysics Data System (ADS)

    Marimuthu, N.; Jerald Wilson, J.; Vinithkumar, N. V.; Kirubagaran, R.

    2013-03-01

    The Andaman and Nicobar Islands are one of the Union Territories of India, located in the eastern part of the Bay of Bengal. In 2010 summer, the increment in sea surface water temperature (up to 34°C) resulted in the bleaching of about 74% to 77% of corals in the South Andaman. During this event, coral species such as Acropora cerealis, A. humilis, Montipora sp., Favia pallida, Diploastrea sp., Goniopora sp. Fungia concinna, Gardineroseries sp., Porites sp., Favites abdita and Lobophyllia robusta were severely affected. This study is to assess the recovery status of the reef ecosystem by estimating the percentage of Live Coral cover, Bleached coral cover, Dead coral with algae, Rubble, Sandy flat, Algal assemblage and other associated organisms. The sedimentation rate (mg cm-2 d-1) and coral coverage (%) were assessed during this study period. The average sedimentation rate was ranged between 0.27 and 0.89 mg cm-2 d-1. The observed post bleaching recovery of coral cover was 21.1% at Port Blair Bay and 13.29% at Havelock Island. The mortality rate of coral cover due to this bleaching was estimated as 2.05% at Port Blair Bay and 9.82% at Havelock Island. Once the sea water temperature resumed back to the normal condition, most of the corals were found recovered.

  1. Changes in Caribbean coral disease prevalence after the 2005 bleaching event.

    PubMed

    Cróquer, Aldo; Weil, Ernesto

    2009-11-16

    Bleaching events and disease epizootics have increased during the past decades, suggesting a positive link between these 2 causes in producing coral mortality. However, studies to test this hypothesis, integrating a broad range of hierarchical spatial scales from habitats to distant localities, have not been conducted in the Caribbean. In this study, we examined links between bleaching intensity and disease prevalence collected from 6 countries, 2 reef sites for each country, and 3 habitats within each reef site (N = 6 x 2 x 3 = 36 site-habitat combinations) during the peak of bleaching in 2005 and a year after, in 2006. Patterns of disease prevalence and bleaching were significantly correlated (Rho = 0.58, p = 0.04). Higher variability in disease prevalence after bleaching occurred among habitats at each particular reef site, with a significant increase in prevalence recorded in 4 of the 10 site-habitats where bleaching was intense and a non-significant increase in disease prevalence in 18 out of the 26 site-habitats where bleaching was low to moderate. A significant linear correlation was found (r = 0.89, p = 0.008) between bleaching and the prevalence of 2 virulent diseases (yellow band disease and white plague) affecting the Montastraea species complex. Results of this study suggest that if bleaching events become more intense and frequent, disease-related mortality of Caribbean coral reef builders could increase, with uncertain effects on coral reef resilience.

  2. Prediction of coral bleaching in the Florida Keys using remotely sensed data

    NASA Astrophysics Data System (ADS)

    Barnes, Brian B.; Hallock, Pamela; Hu, Chuanmin; Muller-Karger, Frank; Palandro, David; Walter, Cory; Zepp, Richard

    2015-06-01

    Shallow water tropical coral reefs may bleach due to extremes in a variety of environmental factors. Of particular concern have been temperature, ultraviolet radiation, and photosynthetically available radiation. Satellite observation systems allow synoptic-scale monitoring of coral environments that can be used to investigate the effects of such environmental parameters. Recent advancements in algorithm development for new satellite data products have made it possible to include light availability in such monitoring. Long-term satellite data (2000-2013), in combination with in situ bleaching surveys ( N = 3,334; spanning 2003-2012), were used to identify the environmental factors contributing to bleaching of Florida reef tract corals. Stepwise multiple linear regression supports the conclusion that elevated sea surface temperature (SST; partial R {adj/2} = 0.13; p < 0.001) and high visible light levels reaching the benthos (partial R {adj/2} = 0.06; p < 0.001) each independently contributed to coral bleaching. The effect of SST was modulated by significant interactions with wind speed (partial R {adj/2} = 0.03; p < 0.001) and ultraviolet benthic available light (partial R {adj/2} = 0.01; p = 0.022). These relationships were combined via canonical analysis of principal coordinates to create a predictive model of coral reef bleaching for the region. This model predicted `severe bleaching' and `no bleaching' conditions with 69 and 57 % classification success, respectively. This was approximately 2.5 times greater than that predicted by chance and shows improvement over similar models created using only temperature data. The results enhance the understanding of the factors contributing to coral bleaching and allow for weekly assessment of historical and current bleaching stress.

  3. Coral disease following massive bleaching in 2005 causes 60% decline in coral cover on reefs in the US Virgin Islands

    USGS Publications Warehouse

    Miller, J.; Muller, E.; Rogers, C.; Waara, R.; Atkinson, A.; Whelan, K.R.T.; Patterson, M.; Witcher, B.

    2009-01-01

    In the northeast Caribbean, doldrum-like conditions combined with elevated water temperatures in the summer/fall 2005 created the most severe coral bleaching event ever documented within this region. Video monitoring of 100 randomly chosen, permanent transects at five study sites in the US Virgin Islands revealed over 90% of the scleractinian coral cover showed signs of thermal stress by paling or becoming completely white. Lower water temperatures in October allowed some re-coloring of corals; however, a subsequent unprecedented regional outbreak of coral disease affected all sites. Five known diseases or syndromes were recorded; however, most lesions showed signs similar to white plague. Nineteen scleractinian species were affected by disease, with >90% of the disease-induced lesions occurring on the genus Montastraea. The disease outbreak peaked several months after the onset of bleaching at all sites but did not occur at the same time. The mean number of disease-induced lesions increased 51-fold and the mean area of disease-associated mortality increased 13-fold when compared with pre-bleaching disease levels. In the 12 months following the onset of bleaching, coral cover declined at all sites (average loss: 51.5%, range: 42.4-61.8%) reducing the five-site average from 21.4% before bleaching to 10.3% with most mortality caused by white plague disease, not bleaching. Continued losses through October 2007 reduced the average coral cover of the five sites to 8.3% (average 2-year loss: 61.1%, range: 53.0-79.3%). Mean cover by M. annularis (complex) decreased 51%, Colpophyllia natans 78% and Agaricia agaricites 87%. Isolated disease outbreaks have been documented before in the Virgin Islands, but never as widespread or devastating as the one that occurred after the 2005 Caribbean coral-bleaching event. This study provides insight into the effects of continued seawater warming and subsequent coral bleaching events in the Caribbean and highlights the need to

  4. Coral disease following massive bleaching in 2005 causes 60% decline in coral cover on reefs in the US Virgin Islands

    NASA Astrophysics Data System (ADS)

    Miller, J.; Muller, E.; Rogers, C.; Waara, R.; Atkinson, A.; Whelan, K. R. T.; Patterson, M.; Witcher, B.

    2009-12-01

    In the northeast Caribbean, doldrum-like conditions combined with elevated water temperatures in the summer/fall 2005 created the most severe coral bleaching event ever documented within this region. Video monitoring of 100 randomly chosen, permanent transects at five study sites in the US Virgin Islands revealed over 90% of the scleractinian coral cover showed signs of thermal stress by paling or becoming completely white. Lower water temperatures in October allowed some re-coloring of corals; however, a subsequent unprecedented regional outbreak of coral disease affected all sites. Five known diseases or syndromes were recorded; however, most lesions showed signs similar to white plague. Nineteen scleractinian species were affected by disease, with >90% of the disease-induced lesions occurring on the genus Montastraea. The disease outbreak peaked several months after the onset of bleaching at all sites but did not occur at the same time. The mean number of disease-induced lesions increased 51-fold and the mean area of disease-associated mortality increased 13-fold when compared with pre-bleaching disease levels. In the 12 months following the onset of bleaching, coral cover declined at all sites (average loss: 51.5%, range: 42.4-61.8%) reducing the five-site average from 21.4% before bleaching to 10.3% with most mortality caused by white plague disease, not bleaching. Continued losses through October 2007 reduced the average coral cover of the five sites to 8.3% (average 2-year loss: 61.1%, range: 53.0-79.3%). Mean cover by M. annularis (complex) decreased 51%, Colpophyllia natans 78% and Agaricia agaricites 87%. Isolated disease outbreaks have been documented before in the Virgin Islands, but never as widespread or devastating as the one that occurred after the 2005 Caribbean coral-bleaching event. This study provides insight into the effects of continued seawater warming and subsequent coral bleaching events in the Caribbean and highlights the need to

  5. Predicting coral bleaching in response to environmental stressors using 8 years of global-scale data.

    PubMed

    Yee, Susan Harrell; Barron, Mace G

    2010-02-01

    Coral reefs have experienced extensive mortality over the past few decades as a result of temperature-induced mass bleaching events. There is an increasing realization that other environmental factors, including water mixing, solar radiation, water depth, and water clarity, interact with temperature to either exacerbate bleaching or protect coral from mass bleaching. The relative contribution of these factors to variability in mass bleaching at a global scale has not been quantified, but can provide insights when making large-scale predictions of mass bleaching events. Using data from 708 bleaching surveys across the globe, a framework was developed to predict the probability of moderate or severe bleaching as a function of key environmental variables derived from global-scale remote-sensing data. The ability of models to explain spatial and temporal variability in mass bleaching events was quantified. Results indicated approximately 20% improved accuracy of predictions of bleaching when solar radiation and water mixing, in addition to elevated temperature, were incorporated into models, but predictive accuracy was variable among regions. Results provide insights into the effects of environmental parameters on bleaching at a global scale.

  6. Spectral discrimination of bleached and healthy submerged corals based on principal components analysis

    SciTech Connect

    Holden, H.; LeDrew, E.

    1997-06-01

    Remote discrimination of substrate types in relatively shallow coastal waters has been limited by the spatial and spectral resolution of available sensors. An additional limiting factor is the strong attenuating influence of the water column over the substrate. As a result, there have been limited attempts to map submerged ecosystems such as coral reefs based on spectral characteristics. Both healthy and bleached corals were measured at depth with a hand-held spectroradiometer, and their spectra compared. Two separate principal components analyses (PCA) were performed on two sets of spectral data. The PCA revealed that there is indeed a spectral difference based on health. In the first data set, the first component (healthy coral) explains 46.82%, while the second component (bleached coral) explains 46.35% of the variance. In the second data set, the first component (bleached coral) explained 46.99%; the second component (healthy coral) explained 36.55%; and the third component (healthy coral) explained 15.44 % of the total variance in the original data. These results are encouraging with respect to using an airborne spectroradiometer to identify areas of bleached corals thus enabling accurate monitoring over time.

  7. Nutrient enrichment can increase the susceptibility of reef corals to bleaching

    NASA Astrophysics Data System (ADS)

    Wiedenmann, Jörg; D'Angelo, Cecilia; Smith, Edward G.; Hunt, Alan N.; Legiret, François-Eric; Postle, Anthony D.; Achterberg, Eric P.

    2013-02-01

    Mass coral bleaching, resulting from the breakdown of coral-algal symbiosis has been identified as the most severe threat to coral reef survival on a global scale. Regionally, nutrient enrichment of reef waters is often associated with a significant loss of coral cover and diversity. Recently, increased dissolved inorganic nitrogen concentrations have been linked to a reduction of the temperature threshold of coral bleaching, a phenomenon for which no mechanistic explanation is available. Here we show that increased levels of dissolved inorganic nitrogen in combination with limited phosphate concentrations result in an increased susceptibility of corals to temperature- and light-induced bleaching. Mass spectrometric analyses of the algal lipidome revealed a marked accumulation of sulpholipids under these conditions. Together with increased phosphatase activities, this change indicates that the imbalanced supply of dissolved inorganic nitrogen results in phosphate starvation of the symbiotic algae. Based on these findings we introduce a conceptual model that links unfavourable ratios of dissolved inorganic nutrients in the water column with established mechanisms of coral bleaching. Notably, this model improves the understanding of the detrimental effects of coastal nutrient enrichment on coral reefs, which is urgently required to support knowledge-based management strategies to mitigate the effects of climate change.

  8. Resilience and climate change: lessons from coral reefs and bleaching in the Western Indian Ocean

    NASA Astrophysics Data System (ADS)

    Obura, David O.

    2005-05-01

    The impact of climate change through thermal stress-related coral bleaching on coral reefs of the Western Indian Ocean has been well documented and is caused by rising sea water temperatures associated with background warming trends and extreme climate events. Recent studies have identified a number of factors that may reduce the impact of coral bleaching and mortality at a reef or sub-reef level. However, there is little scientific consensus as yet, and it is unclear how well current science supports the immediate needs of management responses to climate change. This paper provides evidence from the Western Indian Ocean in support of recent hypotheses on coral and reef vulnerability to thermal stress that have been loosely termed 'resistance and resilience to bleaching'. The paper argues for a more explicit definition of terms, and identifies three concepts affecting coral-zooxanthellae holobiont and reef vulnerability to thermal stress previously termed 'resistance to bleaching': 'thermal protection', where some reefs are protected from the thermal conditions that induce bleaching and/or where local physical conditions reduce bleaching and mortality levels; 'thermal resistance', where individual corals bleach to differing degrees to the same thermal stress; and 'thermal tolerance', where individual corals suffer differing levels of mortality when exposed to the same thermal stress. 'Resilience to bleaching' is a special case of ecological resilience, where recovery following large-scale bleaching mortality varies according to ecological and other processes. These concepts apply across multiple levels of biological organization and temporal and spatial scales. Thermal resistance and tolerance are genetic properties and may interact with environmental protection properties resulting in phenotypic variation in bleaching and mortality of corals. The presence or absence of human threats and varying levels of reef management may alter the influence of the above factors

  9. Patterns of gene expression in a scleractinian coral undergoing natural bleaching.

    PubMed

    Seneca, Francois O; Forêt, Sylvain; Ball, Eldon E; Smith-Keune, Carolyn; Miller, David J; van Oppen, Madeleine J H

    2010-10-01

    Coral bleaching is a major threat to coral reefs worldwide and is predicted to intensify with increasing global temperature. This study represents the first investigation of gene expression in an Indo-Pacific coral species undergoing natural bleaching which involved the loss of algal symbionts. Quantitative real-time polymerase chain reaction experiments were conducted to select and evaluate coral internal control genes (ICGs), and to investigate selected coral genes of interest (GOIs) for changes in gene expression in nine colonies of the scleractinian coral Acropora millepora undergoing bleaching at Magnetic Island, Great Barrier Reef, Australia. Among the six ICGs tested, glyceraldehyde 3-phosphate dehydrogenase and the ribosomal protein genes S7 and L9 exhibited the most constant expression levels between samples from healthy-looking colonies and samples from the same colonies when severely bleached a year later. These ICGs were therefore utilised for normalisation of expression data for seven selected GOIs. Of the seven GOIs, homologues of catalase, C-type lectin and chromoprotein genes were significantly up-regulated as a result of bleaching by factors of 1.81, 1.46 and 1.61 (linear mixed models analysis of variance, P < 0.05), respectively. We present these genes as potential coral bleaching response genes. In contrast, three genes, including one putative ICG, showed highly variable levels of expression between coral colonies. Potential variation in microhabitat, gene function unrelated to the stress response and individualised stress responses may influence such differences between colonies and need to be better understood when designing and interpreting future studies of gene expression in natural coral populations.

  10. Inhibition of photosynthetic CO₂ fixation in the coral Pocillopora damicornis and its relationship to thermal bleaching.

    PubMed

    Hill, Ross; Szabó, Milán; ur Rehman, Ateeq; Vass, Imre; Ralph, Peter J; Larkum, Anthony W D

    2014-06-15

    Two inhibitors of the Calvin-Benson cycle [glycolaldehyde (GA) and potassium cyanide (KCN)] were used in cultured Symbiodinium cells and in nubbins of the coral Pocillopora damicornis to test the hypothesis that inhibition of the Calvin-Benson cycle triggers coral bleaching. Inhibitor concentration range-finding trials aimed to determine the appropriate concentration to generate inhibition of the Calvin-Benson cycle, but avoid other metabolic impacts to the symbiont and the animal host. Both 3 mmol l(-1) GA and 20 μmol l(-1) KCN caused minimal inhibition of host respiration, but did induce photosynthetic impairment, measured by a loss of photosystem II function and oxygen production. GA did not affect the severity of bleaching, nor induce bleaching in the absence of thermal stress, suggesting inhibition of the Calvin-Benson cycle by GA does not initiate bleaching in P. damicornis. In contrast, KCN did activate a bleaching response through symbiont expulsion, which occurred in the presence and absence of thermal stress. While KCN is an inhibitor of the Calvin-Benson cycle, it also promotes reactive oxygen species formation, and it is likely that this was the principal agent in the coral bleaching process. These findings do not support the hypothesis that temperature-induced inhibition of the Calvin-Benson cycle alone induces coral bleaching.

  11. Opposing forces of aerosol cooling and El Nino drive coral bleaching on Caribbean reefs.

    PubMed

    Gill, Jennifer A; Watkinson, Andrew R; McWilliams, John P; Côté, Isabelle M

    2006-12-05

    Bleaching of corals as a result of elevated sea surface temperatures (SST) is rapidly becoming a primary source of stress for reefs globally; the scale and extent of this threat will depend on how the drivers of SST interact to influence bleaching patterns. We demonstrate how the opposing forces of the El Niño-Southern Oscillation (ENSO) and levels of atmospheric aerosols drive regional-scale patterns of coral bleaching across the Caribbean. When aerosol levels are low, bleaching is largely determined by El Niño strength, but high aerosol levels mitigate the effects of a severe El Niño. High aerosol levels, resulting principally from recent volcanic activity, have thus protected Caribbean reefs from more frequent widespread bleaching events but cannot be relied on to provide similar protection in the future.

  12. Physiological and Biogeochemical Traits of Bleaching and Recovery in the Mounding Species of Coral Porites lobata: Implications for Resilience in Mounding Corals

    DTIC Science & Technology

    2013-05-02

    biomass. With the frequency and intensity of bleaching events expected to increase over the next century, coral diversity on future reefs may favor not...Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina, United States of America Introduction Coral reefs are...coming decades [4,6,7], and are already causing mass coral reef decline worldwide [8]. Coral bleaching suscepti- bility has been directly linked to the

  13. Boring sponges, an increasing threat for coral reefs affected by bleaching events.

    PubMed

    Carballo, José L; Bautista, Eric; Nava, Héctor; Cruz-Barraza, José A; Chávez, Jesus A

    2013-04-01

    Coral bleaching is a stress response of corals induced by a variety of factors, but these events have become more frequent and intense in response to recent climate-change-related temperature anomalies. We tested the hypothesis that coral reefs affected by bleaching events are currently heavily infested by boring sponges, which are playing a significant role in the destruction of their physical structure. Seventeen reefs that cover the entire distributional range of corals along the Mexican Pacific coast were studied between 2005/2006, and later between 2009/2010. Most of these coral reefs were previously impacted by bleaching events, which resulted in coral mortalities. Sponge abundance and species richness was used as an indicator of bioerosion, and coral cover was used to describe the present condition of coral reefs. Coral reefs are currently highly invaded (46% of the samples examined) by a very high diversity of boring sponges (20 species); being the coral reef framework the substrate most invaded (56%) followed by the rubbles (45%), and the living colonies (36%). The results also indicated that boring sponges are promoting the dislodgment of live colonies and large fragments from the framework. In summary, the eastern coral reefs affected by bleaching phenomena, mainly provoked by El Niño, present a high diversity and abundance of boring sponges, which are weakening the union of the colony with the reef framework and promoting their dislodgment. These phenomena will probably become even more intense and severe, as temperatures are projected to continue to rise under the scenarios for future climate change, which could place many eastern coral reefs beyond their survival threshold.

  14. Boring sponges, an increasing threat for coral reefs affected by bleaching events

    PubMed Central

    Carballo, José L; Bautista, Eric; Nava, Héctor; Cruz-Barraza, José A; Chávez, Jesus A

    2013-01-01

    Coral bleaching is a stress response of corals induced by a variety of factors, but these events have become more frequent and intense in response to recent climate-change-related temperature anomalies. We tested the hypothesis that coral reefs affected by bleaching events are currently heavily infested by boring sponges, which are playing a significant role in the destruction of their physical structure. Seventeen reefs that cover the entire distributional range of corals along the Mexican Pacific coast were studied between 2005/2006, and later between 2009/2010. Most of these coral reefs were previously impacted by bleaching events, which resulted in coral mortalities. Sponge abundance and species richness was used as an indicator of bioerosion, and coral cover was used to describe the present condition of coral reefs. Coral reefs are currently highly invaded (46% of the samples examined) by a very high diversity of boring sponges (20 species); being the coral reef framework the substrate most invaded (56%) followed by the rubbles (45%), and the living colonies (36%). The results also indicated that boring sponges are promoting the dislodgment of live colonies and large fragments from the framework. In summary, the eastern coral reefs affected by bleaching phenomena, mainly provoked by El Niño, present a high diversity and abundance of boring sponges, which are weakening the union of the colony with the reef framework and promoting their dislodgment. These phenomena will probably become even more intense and severe, as temperatures are projected to continue to rise under the scenarios for future climate change, which could place many eastern coral reefs beyond their survival threshold. PMID:23610632

  15. Coscinaraea marshae corals that have survived prolonged bleaching exhibit signs of increased heterotrophic feeding

    NASA Astrophysics Data System (ADS)

    Bessell-Browne, Pia; Stat, Michael; Thomson, Damian; Clode, Peta L.

    2014-09-01

    Colonies of Coscinaraea marshae corals from Rottnest Island, Western Australia have survived for more than 11 months in various bleached states following a severe heating event in the austral summer of 2011. These colonies are situated in a high-latitude, mesophotic environment, which has made their long-term survival of particular interest as such environments typically suffer from minimal thermal pressures. We have investigated corals that remain unbleached, moderately bleached, or severely bleached to better understand potential survival mechanisms utilised in response to thermal stress. Specifically, Symbiodinium (algal symbiont) density and genotype, chlorophyll- a concentrations, and δ13C and δ15N levels were compared between colonies in the three bleaching categories. Severely bleached colonies housed significantly fewer Symbiodinium cells ( p < 0.05) and significantly reduced chlorophyll- a concentrations ( p < 0.05), compared with unbleached colonies. Novel Symbiodinium clade associations were observed for this coral in both severely and moderately bleached colonies, with clade C and a mixed clade population detected. In unbleached colonies, only clade B was observed. Levels of δ15N indicate that severely bleached colonies are utilising heterotrophic feeding mechanisms to aid survival whilst bleached. Collectively, these results suggest that these C. marshae colonies can survive with low symbiont and chlorophyll densities, in response to prolonged thermal stress and extended bleaching, and increase heterotrophic feeding levels sufficiently to meet energy demands, thus enabling some colonies to survive and recover over long time frames. This is significant as it suggests that corals in mesophotic and high-latitude environments may possess considerable plasticity and an ability to tolerate and adapt to large environmental fluctuations, thereby improving their chances of survival as climate change impacts coral ecosystems worldwide.

  16. An evaluation of the effect of recent temperature variability on the prediction of coral bleaching events.

    PubMed

    Donner, Simon D

    2011-07-01

    Over the past 30 years, warm thermal disturbances have become commonplace on coral reefs worldwide. These periods of anomalous sea surface temperature (SST) can lead to coral bleaching, a breakdown of the symbiosis between the host coral and symbiotic dinoflagellates which reside in coral tissue. The onset of bleaching is typically predicted to occur when the SST exceeds a local climatological maximum by 1 degrees C for a month or more. However, recent evidence suggests that the threshold at which bleaching occurs may depend on thermal history. This study uses global SST data sets (HadISST and NOAA AVHRR) and mass coral bleaching reports (from Reefbase) to examine the effect of historical SST variability on the accuracy of bleaching prediction. Two variability-based bleaching prediction methods are developed from global analysis of seasonal and interannual SST variability. The first method employs a local bleaching threshold derived from the historical variability in maximum annual SST to account for spatial variability in past thermal disturbance frequency. The second method uses a different formula to estimate the local climatological maximum to account for the low seasonality of SST in the tropics. The new prediction methods are tested against the common globally fixed threshold method using the observed bleaching reports. The results find that estimating the bleaching threshold from local historical SST variability delivers the highest predictive power, but also a higher rate of Type I errors. The second method has the lowest predictive power globally, though regional analysis suggests that it may be applicable in equatorial regions. The historical data analysis suggests that the bleaching threshold may have appeared to be constant globally because the magnitude of interannual variability in maximum SST is similar for many of the world's coral reef ecosystems. For example, the results show that a SST anomaly of 1 degrees C is equivalent to 1.73-2.94 standard

  17. Potential role of the ocean thermostat in determining regional differences in coral reef bleaching events

    NASA Astrophysics Data System (ADS)

    Kleypas, Joan A.; Danabasoglu, Gokhan; Lough, Janice M.

    2008-02-01

    Several negative feedback mechanisms have been proposed by others to explain the stability of maximum sea surface temperature (SST) in the western Pacific warm pool (WPWP). If these ``ocean thermostat'' mechanisms effectively suppress warming in the future, then coral reefs in this region should be less exposed to conditions that favor coral reef bleaching. In this study we look for regional differences in reef exposure and sensitivity to increasing SSTs by comparing reported coral reef bleaching events with observed and modeled SSTs of the last fifty years. Coral reefs within or near the WPWP have had fewer reported bleaching events relative to reefs in other regions. Analysis of SST data indicate that the warmest parts of the WPWP have warmed less than elsewhere in the tropical oceans, which supports the existence of thermostat mechanisms that act to depress warming beyond certain temperature thresholds.

  18. The effects of prolonged ``bleaching'' on the tissue biomass and reproduction of the reef coral Montastrea annularis

    NASA Astrophysics Data System (ADS)

    Szmant, A. M.; Gassman, N. J.

    1990-04-01

    Colonies of Montastrea annularis from Carysfort Reef, Florida, that remained bleached seven months after the 1987 Caribbean bleaching event were studied to determine the long term effects of bleaching on coral physiology. Two types of bleached colonies were found: colonies with low numbers of zooxanthellae with normal pigment content, and a colony with high densities of lowpigment zooxanthellae. In both types, the zooxanthellae had an abnormal distribution within polyp tissues: highest densities were observed in basal endoderm and in mesenteries where zooxanthellae are not normally found. Bleached corals had 30% less tissue carbon and 44% less tissue nitrogen biomass per skeletal surface area, but the same tissue C:N ratio as other colonies that either did not bleach (normal) or that bleached and regained their zooxanthellae (recovered). Bleached corals were not able to complete gametogenesis during the reproductive season following the bleaching, while recovered corals were able to follow a normal gametogenic cycle. It appears that bleached corals were able to survive the prolonged period without nutritional contribution from their zooxanthellae by consuming their own structural materials for maintenance, but then, did not have the resources necessary for reproduction. The recovered corals, on the other hand, must have regained their zooxanthellae soon after the bleaching event since neither their tissue biomass nor their ability to reproduce were impaired.

  19. Metagenomic analysis of the coral holobiont during a natural bleaching event on the Great Barrier Reef.

    PubMed

    Littman, Raechel; Willis, Bette L; Bourne, David G

    2011-12-01

    Understanding the effects of elevated seawater temperatures on each member of the coral holobiont (the complex comprised of coral polyps and associated symbiotic microorganisms, including Bacteria, viruses, Fungi, Archaea and endolithic algae) is becoming increasingly important as evidence accumulates that microbial members contribute to overall coral health, particularly during thermal stress. Here we use a metagenomic approach to identify metabolic and taxonomic shifts in microbial communities associated with the hard coral Acropora millepora throughout a natural thermal bleaching event at Magnetic Island (Great Barrier Reef). A direct comparison of metagenomic data sets from healthy versus bleached corals indicated major shifts in microbial associates during heat stress, including Bacteria, Archaea, viruses, Fungi and micro-algae. Overall, metabolism of the microbial community shifted from autotrophy to heterotrophy, including increases in genes associated with the metabolism of fatty acids, proteins, simple carbohydrates, phosphorus and sulfur. In addition, the proportion of virulence genes was higher in the bleached library, indicating an increase in microorganisms capable of pathogenesis following bleaching. These results demonstrate that thermal stress results in shifts in coral-associated microbial communities that may lead to deteriorating coral health.

  20. Corals escape bleaching in regions that recently and historically experienced frequent thermal stress.

    PubMed

    Thompson, D M; van Woesik, R

    2009-08-22

    The response of coral-reef ecosystems to contemporary thermal stress may be in part a consequence of recent or historical sea-surface temperature (SST) variability. To test this hypothesis, we examined whether: (i) there was a relationship between the historical frequency of SST variability and stress experienced during the most recent thermal-stress events (in 1998 and 2005-2006) and (ii) coral reefs that historically experienced frequent thermal anomalies were less likely to experience coral bleaching during these recent thermal-stress events. Examination of nine detrended coral delta(18)O and Sr/Ca anomaly records revealed a high- (5.7-year) and low-frequency (>54-year) mode of SST variability. There was a positive relationship between the historical frequency of SST anomalies and recent thermal stress; sites historically dominated by the high-frequency mode experienced greater thermal stress than other sites during both events, and showed extensive coral bleaching in 1998. Nonetheless, in 2005-2006, corals at sites dominated by high-frequency variability showed reduced bleaching, despite experiencing high thermal stress. This bleaching resistance was most likely a consequence of rapid directional selection that followed the extreme thermal event of 1998. However, the benefits of regional resistance could come at the considerable cost of shifts in coral species composition.

  1. Landscape ecology of algal symbionts creates variation in episodes of coral bleaching

    NASA Astrophysics Data System (ADS)

    Rowan, Rob; Knowlton, Nancy; Baker, Andrew; Jara, Javier

    1997-07-01

    Reef-building corals are obligate, mutualistic symbioses of heterotrophic animals and phototrophic dinoflagellates (Symbiodinium spp.). Contrary to the earlier, widely accepted belief that corals harbour only one symbiont, we found that the ecologically dominant Caribbean corals Montastraea annularis and M. faveolata can act as hosts to dynamic, multi-species communities of Symbiodinium. Composition of these communities follows gradients of environmental irradiance, implying that physiological acclimatization is not the only mechanism by which corals cope with environmental heterogeneity. The importance of this diversity was underlined by analysis of a natural episode of coral bleaching. Patterns of bleaching could be explained by the preferential elimination of a symbiont associated with low irradiance from the brightest parts of its distribution. Comparative analyses of symbionts before and after bleaching from the same corals supported this interpretation, and suggested that some corals were protected from bleaching by hosting an additional symbiont that is more tolerant of high irradiance and temperature. This `natural experiment' suggests that temporal and spatial variability can favour the coexistence of diverse symbionts within a host, despite the potential for destabilizing competition among them,.

  2. A depth refugium from catastrophic coral bleaching prevents regional extinction.

    PubMed

    Smith, Tyler B; Glynn, Peter W; Maté, Juan L; Toth, Lauren T; Gyory, Joanna

    2014-06-01

    Species intolerant of changing climate might avoid extinction within refugia buffered from extreme conditions. Refugia have been observed in the fossil record but are not well documented or understood on ecological time scales. Using a 37-year record from the eastern Pacific across the two most severe El Niño events on record (1982-1983 and 1997 1998) we show how an exceptionally thermally sensitive reef-building hydrocoral, Millepora intricata, twice survived catastrophic bleaching in a deeper-water refuge (> 11 m depth). During both events, M. intricata was extirpated across its range in shallow water, but showed recovery within several years, while two other hydrocorals without deep-water populations were driven to regional extinction. Evidence from the subfossil record in the same area showed shallow-water persistence of abundant M. intricata populations from 5000 years ago, through severe El Niño-Southern Oscillation cycles, suggesting a potential depth refugium on a millennial timescale. Our data confirm the deep refuge hypothesis for corals under thermal stress.

  3. In vivo Microscale Measurements of Light and Photosynthesis during Coral Bleaching: Evidence for the Optical Feedback Loop?

    PubMed

    Wangpraseurt, Daniel; Holm, Jacob B; Larkum, Anthony W D; Pernice, Mathieu; Ralph, Peter J; Suggett, David J; Kühl, Michael

    2017-01-01

    Climate change-related coral bleaching, i.e., the visible loss of zooxanthellae from the coral host, is increasing in frequency and extent and presents a major threat to coral reefs globally. Coral bleaching has been proposed to involve accelerating light stress of their microalgal endosymbionts via a positive feedback loop of photodamage, symbiont expulsion and excess in vivo light exposure. To test this hypothesis, we used light and O2 microsensors to characterize in vivo light exposure and photosynthesis of Symbiodinium during a thermal stress experiment. We created tissue areas with different densities of Symbiodinium cells in order to understand the optical properties and light microenvironment of corals during bleaching. Our results showed that in bleached Pocillopora damicornis corals, Symbiodinium light exposure was up to fivefold enhanced relative to healthy corals, and the relationship between symbiont loss and light enhancement was well-described by a power-law function. Cell-specific rates of Symbiodinium gross photosynthesis and light respiration were enhanced in bleached P. damicornis compared to healthy corals, while areal rates of net photosynthesis decreased. Symbiodinium light exposure in Favites sp. revealed the presence of low light microniches in bleached coral tissues, suggesting that light scattering in thick coral tissues can enable photoprotection of cryptic symbionts. Our study provides evidence for the acceleration of in vivo light exposure during coral bleaching but this optical feedback mechanism differs between coral hosts. Enhanced photosynthesis in relation to accelerating light exposure shows that coral microscale optics exerts a key role on coral photophysiology and the subsequent degree of radiative stress during coral bleaching.

  4. In vivo Microscale Measurements of Light and Photosynthesis during Coral Bleaching: Evidence for the Optical Feedback Loop?

    PubMed Central

    Wangpraseurt, Daniel; Holm, Jacob B.; Larkum, Anthony W. D.; Pernice, Mathieu; Ralph, Peter J.; Suggett, David J.; Kühl, Michael

    2017-01-01

    Climate change-related coral bleaching, i.e., the visible loss of zooxanthellae from the coral host, is increasing in frequency and extent and presents a major threat to coral reefs globally. Coral bleaching has been proposed to involve accelerating light stress of their microalgal endosymbionts via a positive feedback loop of photodamage, symbiont expulsion and excess in vivo light exposure. To test this hypothesis, we used light and O2 microsensors to characterize in vivo light exposure and photosynthesis of Symbiodinium during a thermal stress experiment. We created tissue areas with different densities of Symbiodinium cells in order to understand the optical properties and light microenvironment of corals during bleaching. Our results showed that in bleached Pocillopora damicornis corals, Symbiodinium light exposure was up to fivefold enhanced relative to healthy corals, and the relationship between symbiont loss and light enhancement was well-described by a power-law function. Cell-specific rates of Symbiodinium gross photosynthesis and light respiration were enhanced in bleached P. damicornis compared to healthy corals, while areal rates of net photosynthesis decreased. Symbiodinium light exposure in Favites sp. revealed the presence of low light microniches in bleached coral tissues, suggesting that light scattering in thick coral tissues can enable photoprotection of cryptic symbionts. Our study provides evidence for the acceleration of in vivo light exposure during coral bleaching but this optical feedback mechanism differs between coral hosts. Enhanced photosynthesis in relation to accelerating light exposure shows that coral microscale optics exerts a key role on coral photophysiology and the subsequent degree of radiative stress during coral bleaching. PMID:28174567

  5. A comparison between boat-based and diver-based methods for quantifying coral bleaching

    USGS Publications Warehouse

    Zawada, David G.; Ruzicka, Rob; Colella, Michael A.

    2015-01-01

    Recent increases in both the frequency and severity of coral bleaching events have spurred numerous surveys to quantify the immediate impacts and monitor the subsequent community response. Most of these efforts utilize conventional diver-based methods, which are inherently time-consuming, expensive, and limited in spatial scope unless they deploy large teams of scientifically-trained divers. In this study, we evaluated the effectiveness of the Along-Track Reef Imaging System (ATRIS), an automated image-acquisition technology, for assessing a moderate bleaching event that occurred in the summer of 2011 in the Florida Keys. More than 100,000 images were collected over 2.7 km of transects spanning four patch reefs in a 3-h period. In contrast, divers completed 18, 10-m long transects at nine patch reefs over a 5-day period. Corals were assigned to one of four categories: not bleached, pale, partially bleached, and bleached. The prevalence of bleaching estimated by ATRIS was comparable to the results obtained by divers, but only for corals > 41 cm in size. The coral size-threshold computed for ATRIS in this study was constrained by prevailing environmental conditions (turbidity and sea state) and, consequently, needs to be determined on a study-by-study basis. Both ATRIS and diver-based methods have innate strengths and weaknesses that must be weighed with respect to project goals.

  6. The Role of Intra-Island Temperature Variability at Palmyra Atoll in Mass Coral Bleaching Events

    NASA Astrophysics Data System (ADS)

    Urmy, S.; McNally, J.; Bartz, J.; Dunbar, R.

    2008-12-01

    Mass coral bleaching events have been reported in Palmyra Atoll during severe El Niños in the last 30 years, and are thought to be increasing both in frequency and magnitude. During these events, bleaching is highly localized, with some parts of the reef showing a much greater effect than others. NOAA's Coral Reef Watch monitors thermal stress on corals by calculating degree heating weeks (DHW) from satellite sea surface temperature in a 50 km pixel around each reef group or atoll of interest. While this technique allows some predictive capacity, especially for mass bleaching events, it does not consider the effects of reef geometry on bleaching susceptibility at different reef groups (Hoeke et al., 2006). Furthermore, because of its large scale, it cannot differentiate between open ocean, backreef, or lagoon temperatures. This project compiles high resolution temperature time series recorded in situ at a number of locations on the reef at Palmyra from 2002-2008, with surprising results. At any one given time, corals at different locations around the atoll may be experiencing temperature stresses that are significantly different both between locations and from the satellite DHW product. Shallow reef flats appear to be a source of heated water that, if advected elsewhere on the reef, may stress corals in normally cooler locations. A more thorough understanding of these mechanisms could improve our predictive capability as to which areas of the reef are at greatest risk if mass bleaching events continue to increase in severity and frequency.

  7. The effect of species and colony size on the bleaching response of reef-building corals in the Florida Keys during the 2005 mass bleaching event

    NASA Astrophysics Data System (ADS)

    Brandt, M. E.

    2009-12-01

    Understanding the variation in coral bleaching response is necessary for making accurate predictions of population changes and the future state of reefs in a climate of increasing thermal stress events. Individual coral colonies, belonging to inshore patch reef communities of the Florida Keys, were followed through the 2005 mass bleaching event. Overall, coral bleaching patterns followed an index of accumulated thermal stress more closely than in situ temperature measurements. Eight coral species ( Colpophyllia natans, Diploria strigosa, Montastraea cavernosa, M. faveolata, Porites astreoides, P. porites, Siderastrea siderea, and Stephanocoenia intersepta), representing >90% of the coral colonies studied, experienced intense levels of bleaching, but responses varied. Bleaching differed significantly among species: Colpophyllia natans and Diploria strigosa were most susceptible to thermal stress, while Stephanocoenia intersepta was the most tolerant. For colonies of C. natans, M. faveolata, and S. siderea, larger colonies experienced more extensive bleaching than smaller colonies. The inshore patch reef communities of the Florida Keys have historically been dominated by large colonies of Montastraea sp. and Colpophyllia natans. These results provide evidence that colony-level differences can affect bleaching susceptibility in this habitat and suggest that the impact of future thermal stress events may be biased toward larger colonies of dominant reef-building species. Predicted increases in the frequency of mass bleaching and subsequent mortality may therefore result in significant structural shifts of these ecologically important communities.

  8. Apoptosis and the selective survival of host animals following thermal bleaching in zooxanthellate corals.

    PubMed

    Tchernov, Dan; Kvitt, Hagit; Haramaty, Liti; Bibby, Thomas S; Gorbunov, Maxim Y; Rosenfeld, Hanna; Falkowski, Paul G

    2011-06-14

    During the past several decades, numerous reports from disparate geographical areas have documented an increased frequency of "bleaching" in reef-forming corals. The phenomenon, triggered by increased sea surface temperatures, occurs when the cnidarian hosts digest and/or expel their intracellular, photosynthetic dinoflagellate symbionts ("zooxanthellae" in the genus Symbiodinium). Although coral bleaching is often followed by the death of the animal hosts, in some cases, the animal survives and can be repopulated with viable zooxanthellae. The physiological factors determining the ability of the coral to survive bleaching events are poorly understood. In this study, we experimentally established that bleaching and death of the host animal involve a caspase-mediated apoptotic cascade induced by reactive oxygen species produced primarily by the algal symbionts. In addition, we demonstrate that, although some corals naturally suppress caspase activity and significantly reduce caspase concentration under high temperatures as a mechanism to prevent colony death from apoptosis, even sensitive corals can be prevented from dying by application of exogenous inhibitors of caspases. Our results indicate that variability in response to thermal stress in corals is determined by a four-element, combinatorial genetic matrix intrinsic to the specific symbiotic association. Based on our experimental data, we present a working model in which the phenotypic expression of this symbiont/host relationship places a selective pressure on the symbiotic association. The model predicts the survival of the host animals in which the caspase-mediated apoptotic cascade is down-regulated.

  9. Recovery of the coral Montastrea annularis in the Florida Keys after the 1987 Caribbean ``bleaching event''

    NASA Astrophysics Data System (ADS)

    Fitt, William K.; Spero, Howard J.; Halas, John; White, Michael W.; Porter, James W.

    1993-07-01

    Many reef-building corals and other cnidarians lost photosynthetic pigments and symbiotic algae (zooxanthellae) during the coral bleaching event in the Caribbean in 1987. The Florida Reef Tract included some of the first documented cases, with widespread bleaching of the massive coral Montastrea annularis beginning in late August. Phototransects at Carysfort Reef showed discoloration of >90% of colonies of this species in March 1988 compared to 0% in July 1986; however no mortality was observed between 1986 and 1988. Samples of corals collected in February and June 1988 had zooxanthellae densities ranging from 0.1 in the most lightly colored corals, to 1.6x106 cells/cm2 in the darker corals. Minimum densities increased to 0.5x106 cells/cm2 by August 1989. Chlorophyll- a content of zooxanthellae and zooxanthellar mitotic indices were significantly higher in corals with lower densities of zooxanthellae, suggesting that zooxanthellar at low densities may be more nutrientsufficient than those in unbleached corals. Ash-free dry weight of coral tissue was positively correlated with zooxanthellae density at all sample times and was significantly lower in June 1988 compared to August 1989. Proteins and lipids per cm2 were significantly higher in August 1989 than in February or June, 1988. Although recovery of zooxanthellae density and coral pigmentation to normal levels may occur in less than one year, regrowth of tissue biomass and energy stores lost during the period of low symbiont densities may take significantly longer.

  10. Bleaching, coral mortality and subsequent survivorship on a West Australian fringing reef

    NASA Astrophysics Data System (ADS)

    Depczynski, M.; Gilmour, J. P.; Ridgway, T.; Barnes, H.; Heyward, A. J.; Holmes, T. H.; Moore, J. A. Y.; Radford, B. T.; Thomson, D. P.; Tinkler, P.; Wilson, S. K.

    2013-03-01

    The spring and summer of 2010/11 saw an exceptionally strong La Niña push warm waters from Indonesia down the Western Australian coastline, resulting in a host of extraordinary biological oddities including significant bleaching of Western Australian corals. Here, we report a 79-92 % decline in coral cover for a location in the Ningaloo Marine Park where sustained high water temperatures over an 8-month period left just 1-6 % of corals alive. The severity of bleaching provided an opportunity to investigate the resilience of different taxonomic groups and colony size classes to an acute but protracted episode of thermal stress. While the sub-dominant community of massive growth forms fared reasonably well, the dominant Acropora and Montipora assemblages all died, with the exception of the <10 cm size class, which seemed immune to bleaching.

  11. Opposite latitudinal gradients in projected ocean acidification and bleaching impacts on coral reefs.

    PubMed

    van Hooidonk, Ruben; Maynard, Jeffrey Allen; Manzello, Derek; Planes, Serge

    2014-01-01

    Coral reefs and the services they provide are seriously threatened by ocean acidification and climate change impacts like coral bleaching. Here, we present updated global projections for these key threats to coral reefs based on ensembles of IPCC AR5 climate models using the new Representative Concentration Pathway (RCP) experiments. For all tropical reef locations, we project absolute and percentage changes in aragonite saturation state (Ωarag) for the period between 2006 and the onset of annual severe bleaching (thermal stress >8 degree heating weeks); a point at which it is difficult to believe reefs can persist as we know them. Severe annual bleaching is projected to start 10-15 years later at high-latitude reefs than for reefs in low latitudes under RCP8.5. In these 10-15 years, Ωarag keeps declining and thus any benefits for high-latitude reefs of later onset of annual bleaching may be negated by the effects of acidification. There are no long-term refugia from the effects of both acidification and bleaching. Of all reef locations, 90% are projected to experience severe bleaching annually by 2055. Furthermore, 5% declines in calcification are projected for all reef locations by 2034 under RCP8.5, assuming a 15% decline in calcification per unit of Ωarag. Drastic emissions cuts, such as those represented by RCP6.0, result in an average year for the onset of annual severe bleaching that is ~20 years later (2062 vs. 2044). However, global emissions are tracking above the current worst-case scenario devised by the scientific community, as has happened in previous generations of emission scenarios. The projections here for conditions on coral reefs are dire, but provide the most up-to-date assessment of what the changing climate and ocean acidification mean for the persistence of coral reefs.

  12. Long-term impacts of coral bleaching events on the world's warmest reefs.

    PubMed

    Burt, John; Al-Harthi, Suaad; Al-Cibahy, Ashraf

    2011-10-01

    The southern Arabian Gulf houses some of the most thermally tolerant corals on earth, but severe bleaching in the late 1990s caused widespread mortality. More than a decade later, corals still dominated benthos (mean: 40 ± 3% cover on 10 sites spanning > 350 km; range: 11.0-65.6%), but coral communities varied spatially. Sites to the west generally had low species richness and coral cover (mean: 3.2 species per transect, 31% cover), with Porites dominated communities (88% of coral) that are distinct from more diverse and higher cover eastern sites (mean: 10.3 species per transect, 62% cover). These patterns reflect both the more extreme bleaching to the west in the late 1990s as well as the higher faviid dominated recruitment to the east in subsequent years. There has been limited recovery of the formerly dominant Acropora, which now represents <1% of the benthos, likely as a result of recruitment failure. Results indicate that severe bleaching can have substantial long-term impacts on coral communities, even in areas with corals tolerant to environmental extremes.

  13. The effects of ultraviolet radiation on growth and bleaching in three species of Hawaiian coral

    SciTech Connect

    Goodman, G.D. )

    1990-01-09

    Long term exposure to ultraviolet radiation is harmful to many organisms, including hermatypic corals, which obtain much of their nutrition from photosynthetic zooxanthellae. Therefore, increased UV radiation from atmospheric ozone depletion could inhibit growth of such corals. Moreover, coral bleaching, which has been attributed to loss of pigment and/or expulsion of zooxanthellae, may be a specific response to UV light. Does UV-A reduce skeletal growth or influence population density and pigment content of zooxanthellae In addition, do zooxanthellae migrate to shaded areas of the colony to avoid ultraviolet light Using alizarin red stain and suitable filters, I compared the stain and suitable filters, I compared the effects of UV-A (320-400nm) and full-spectrum UV (280-400nm) on the skeletal growth of two Hawaiian corals, Montipora verrucosa, Pocillopora damicornis, in situ. In the perforate corals, M. Verrucosa and Porites compressa, I measured concentration of zooxanthellae and their chlorophyll content to quantify bleaching in response to UV light. Reduction in skeletal growth by the two corals in response to different ranges of UV light appears to be species specific. Bleaching by UV appears to be characterized by an initial loss of pigment followed by the expulsion and migration of the zooxanthellae to shaded areas of the colony. Differences in tolerance and adaptation to decreasing ozone levels and increasing UV light should confer a competitive advantage on various species and morphologies of reef-building corals.

  14. The 2014 coral bleaching and freshwater flood events in Kāne'ohe Bay, Hawai'i.

    PubMed

    Bahr, Keisha D; Jokiel, Paul L; Rodgers, Kuʻulei S

    2015-01-01

    Until recently, subtropical Hawai'i escaped the major bleaching events that have devastated many tropical regions, but the continued increases in global long-term mean temperatures and the apparent ending of the Pacific Decadal Oscillation (PDO) cool phase have increased the risk of bleaching events. Climate models and observations predict that bleaching in Hawai'i will occur with increasing frequency and increasing severity over future decades. A freshwater "kill" event occurred during July 2014 in the northern part of Kāne'ohe Bay that reduced coral cover by 22.5% in the area directly impacted by flooding. A subsequent major bleaching event during September 2014 caused extensive coral bleaching and mortality throughout the bay and further reduced coral cover in the freshwater kill area by 60.0%. The high temperature bleaching event only caused a 1.0% reduction in live coral throughout the portion of the bay not directly impacted by the freshwater event. Thus, the combined impact of the low salinity event and the thermal bleaching event appears to be more than simply additive. The temperature regime during the September 2014 bleaching event was analogous in duration and intensity to that of the large bleaching event that occurred previously during August 1996, but resulted in a much larger area of bleaching and coral mortality. Apparently seasonal timing as well as duration and magnitude of heating is important. Coral spawning in the dominant coral species occurs early in the summer, so reservoirs of stored lipid in the corals had been depleted by spawning prior to the September 2014 event. Warm months above 27 °C result in lower coral growth and presumably could further decrease lipid reserves, leading to a bleaching event that was more severe than would have happened if the high temperatures occurred earlier in the summer. Hawaiian reef corals decrease skeletal growth at temperatures above 27 °C, so perhaps the "stress period" actually started long before the

  15. A strategic framework for responding to coral bleaching events in a changing climate.

    PubMed

    Maynard, J A; Johnson, J E; Marshall, P A; Eakin, C M; Goby, G; Schuttenberg, H; Spillman, C M

    2009-07-01

    The frequency and severity of mass coral bleaching events are predicted to increase as sea temperatures continue to warm under a global regime of rising ocean temperatures. Bleaching events can be disastrous for coral reef ecosystems and, given the number of other stressors to reefs that result from human activities, there is widespread concern about their future. This article provides a strategic framework from the Great Barrier Reef to prepare for and respond to mass bleaching events. The framework presented has two main inter-related components: an early warning system and assessment and monitoring. Both include the need to proactively and consistently communicate information on environmental conditions and the level of bleaching severity to senior decision-makers, stakeholders, and the public. Managers, being the most timely and credible source of information on bleaching events, can facilitate the implementation of strategies that can give reefs the best chance to recover from bleaching and to withstand future disturbances. The proposed framework is readily transferable to other coral reef regions, and can easily be adapted by managers to local financial, technical, and human resources.

  16. Modeling patterns of coral bleaching at a remote Central Pacific atoll.

    PubMed

    Williams, Gareth J; Knapp, Ingrid S; Maragos, James E; Davy, Simon K

    2010-09-01

    A mild bleaching event (9.2% prevalence) at Palmyra Atoll occurred in response to the 2009 ENSO, when mean water temperature reached 29.8-30.1 degrees C. Prevalence among both abundant and sparse taxa varied with no clear pattern in susceptibility relating to coral morphology. Seven taxon-specific models showed that turbidity exacerbated while prior exposure to higher background temperatures alleviated bleaching, with these predictors explaining an average 16.3% and 11.5% variation in prevalence patterns, respectively. Positive associations occurred between bleaching prevalence and both immediate temperature during the bleaching event (average 8.4% variation explained) and increased sand cover (average 3.7%). Despite these associations, mean unexplained variation in prevalence equalled 59%. Lower bleaching prevalence in areas experiencing higher background temperatures suggests acclimation to temperature stress among several coral genera, while WWII modifications may still be impacting the reefs via shoreline sediment re-distribution and increased turbidity, exacerbating coral bleaching susceptibility during periods of high temperature stress.

  17. A Strategic Framework for Responding to Coral Bleaching Events in a Changing Climate

    NASA Astrophysics Data System (ADS)

    Maynard, J. A.; Johnson, J. E.; Marshall, P. A.; Eakin, C. M.; Goby, G.; Schuttenberg, H.; Spillman, C. M.

    2009-07-01

    The frequency and severity of mass coral bleaching events are predicted to increase as sea temperatures continue to warm under a global regime of rising ocean temperatures. Bleaching events can be disastrous for coral reef ecosystems and, given the number of other stressors to reefs that result from human activities, there is widespread concern about their future. This article provides a strategic framework from the Great Barrier Reef to prepare for and respond to mass bleaching events. The framework presented has two main inter-related components: an early warning system and assessment and monitoring. Both include the need to proactively and consistently communicate information on environmental conditions and the level of bleaching severity to senior decision-makers, stakeholders, and the public. Managers, being the most timely and credible source of information on bleaching events, can facilitate the implementation of strategies that can give reefs the best chance to recover from bleaching and to withstand future disturbances. The proposed framework is readily transferable to other coral reef regions, and can easily be adapted by managers to local financial, technical, and human resources.

  18. Histological observations in the Hawaiian reef coral, Porites compressa, affected by Porites bleaching with tissue loss.

    PubMed

    Sudek, M; Work, T M; Aeby, G S; Davy, S K

    2012-10-01

    The scleractinian finger coral Porites compressa is affected by the coral disease Porites bleaching with tissue loss (PBTL). This disease initially manifests as bleaching of the coenenchyme (tissue between polyps) while the polyps remain brown with eventual tissue loss and subsequent algal overgrowth of the bare skeleton. Histopathological investigation showed a loss of symbiont and melanin-containing granular cells which was more pronounced in the coenenchyme than the polyps. Cell counts confirmed a 65% reduction in symbiont density. Tissue loss was due to tissue fragmentation and necrosis in affected areas. In addition, a reduction in putative bacterial aggregate densities was found in diseased samples but no potential pathogens were observed.

  19. Vibrio shiloi sp. nov., the causative agent of bleaching of the coral Oculina patagonica.

    PubMed

    Kushmaro, A; Banin, E; Loya, Y; Stackebrandt, E; Rosenberg, E

    2001-07-01

    The aetiological agent of bleaching of the coral Oculina patagonica was characterized as a new Vibrio species on the basis of 16S rDNA sequence, DNA-DNA hybridization data and phenotypic properties, including the cellular fatty acid profile. Based on its 16S rDNA and DNA-DNA hybridization, the new Vibrio species is closely related to Vibrio mediterranei. The name Vibrio shiloi sp. nov. is proposed for the new coral-bleaching species, the type strain being AK1T (= ATCC BAA-91T = DSM 13774T).

  20. Histological observations in the Hawaiian reef coral, Porites compressa, affected by Porites bleaching with tissue loss

    USGS Publications Warehouse

    Sudek, M.; Work, T.M.; Aeby, G.S.; Davy, S.K.

    2012-01-01

    The scleractinian finger coral Porites compressa is affected by the coral disease Porites bleaching with tissue loss (PBTL). This disease initially manifests as bleaching of the coenenchyme (tissue between polyps) while the polyps remain brown with eventual tissue loss and subsequent algal overgrowth of the bare skeleton. Histopathological investigation showed a loss of symbiont and melanin-containing granular cells which was more pronounced in the coenenchyme than the polyps. Cell counts confirmed a 65% reduction in symbiont density. Tissue loss was due to tissue fragmentation and necrosis in affected areas. In addition, a reduction in putative bacterial aggregate densities was found in diseased samples but no potential pathogens were observed.

  1. Turning up the Heat: Increasing Temperature and Coral Bleaching at the High Latitude Coral Reefs of the Houtman Abrolhos Islands

    PubMed Central

    Abdo, David A.; Bellchambers, Lynda M.; Evans, Scott N.

    2012-01-01

    Background Coral reefs face increasing pressures particularly when on the edge of their distributions. The Houtman Abrolhos Islands (Abrolhos) are the southernmost coral reef system in the Indian Ocean, and one of the highest latitude reefs in the world. These reefs have a unique mix of tropical and temperate marine fauna and flora and support 184 species of coral, dominated by Acropora species. A significant La Niña event during 2011 produced anomalous conditions of increased temperature along the whole Western Australian coastline, producing the first-recorded widespread bleaching of corals at the Abrolhos. Methodology/ Principal Findings We examined long term trends in the marine climate at the Abrolhos using historical sea surface temperature data (HadISST data set) from 1900–2011. In addition in situ water temperature data for the Abrolhos (from data loggers installed in 2008, across four island groups) were used to determine temperature exposure profiles. Coupled with the results of coral cover surveys conducted annually since 2007; we calculated bleaching thresholds for monitoring sites across the four Abrolhos groups. Conclusions/ Significance In situ temperature data revealed maximum daily water temperatures reached 29.54°C in March 2011 which is 4.2°C above mean maximum daily temperatures (2008–2010). The level of bleaching varied across sites with an average of ∼12% of corals bleached. Mortality was high, with a mean ∼50% following the 2011 bleaching event. Prior to 2011, summer temperatures reached a mean (across all monitoring sites) of 25.1°C for 2.5 days. However, in 2011 temperatures reached a mean of 28.1°C for 3.3 days. Longer term trends (1900–2011) showed mean annual sea surface temperatures increase by 0.01°C per annum. Long-term temperature data along with short-term peaks in 2011, outline the potential for corals to be exposed to more frequent bleaching risk with consequences for this high latitude coral reef system at the

  2. Nitric oxide and coral bleaching: is peroxynitrite generation required for symbiosis collapse?

    PubMed

    Hawkins, Thomas D; Davy, Simon K

    2013-09-01

    The temperature-induced collapse ('bleaching') of the coral-dinoflagellate symbiosis is hypothesised to result from symbiont oxidative stress and a subsequent host innate immune-like response. This includes the production of nitric oxide (NO), which is involved in numerous microbial symbioses. Much of NO's cytotoxicity has been attributed to its conversion, in the presence of superoxide (O2(-)), to highly reactive peroxynitrite (ONOO(-)). However, ONOO(-) generation has yet to be observed in either a lower invertebrate or an intracellular mutualism. Using confocal laser scanning microscopy with the fluorescent ONOO(-) indicator aminophenyl fluorescein (APF), we observed strong evidence that ONOO(-) is generated in symbiotic Aiptasia pulchella under conditions known to induce thermal bleaching. However, a role for ONOO(-) in bleaching remains unclear as treatment with a peroxynitrite scavenger had no significant effect on thermal bleaching. Therefore, while ONOO(-) may have a potential for cytotoxicity, in vivo levels of the compound may be insufficient to affect bleaching.

  3. Rapid transition in the structure of a coral reef community: the effects of coral bleaching and physical disturbance.

    PubMed

    Ostrander, G K; Armstrong, K M; Knobbe, E T; Gerace, D; Scully, E P

    2000-05-09

    Coral reef communities are in a state of change throughout their geographical range. Factors contributing to this change include bleaching (the loss of algal symbionts), storm damage, disease, and increasing abundance of macroalgae. An additional factor for Caribbean reefs is the aftereffects of the epizootic that reduced the abundance of the herbivorous sea urchin, Diadema antillarum. Although coral reef communities have undergone phase shifts, there are few studies that document the details of such transitions. We report the results of a 40-month study that documents changes in a Caribbean reef community affected by bleaching, hurricane damage, and an increasing abundance of macroalgae. The study site was in a relatively pristine area of the reef surrounding the island of San Salvador in the Bahamas. Ten transects were sampled every 3-9 months from November 1994 to February 1998. During this period, the corals experienced a massive bleaching event resulting in a significant decline in coral abundance. Algae, especially macroalgae, increased in abundance until they effectively dominated the substrate. The direct impact of Hurricane Lili in October 1996 did not alter the developing community structure and may have facilitated increasing algal abundance. The results of this study document the rapid transition of this reef community from one in which corals and algae were codominant to a community dominated by macroalgae. The relatively brief time period required for this transition illustrates the dynamic nature of reef communities.

  4. Physiological and biogeochemical traits of bleaching and recovery in the mounding species of coral Porites lobata: implications for resilience in mounding corals.

    PubMed

    Levas, Stephen J; Grottoli, Andréa G; Hughes, Adam; Osburn, Christopher L; Matsui, Yohei

    2013-01-01

    Mounding corals survive bleaching events in greater numbers than branching corals. However, no study to date has determined the underlying physiological and biogeochemical trait(s) that are responsible for mounding coral holobiont resilience to bleaching. Furthermore, the potential of dissolved organic carbon (DOC) as a source of fixed carbon to bleached corals has never been determined. Here, Porites lobata corals were experimentally bleached for 23 days and then allowed to recover for 0, 1, 5, and 11 months. At each recovery interval a suite of analyses were performed to assess their recovery (photosynthesis, respiration, chlorophyll a, energy reserves, tissue biomass, calcification, δ(13)C of the skeletal, δ(13)C, and δ(15)N of the animal host and endosymbiont fractions). Furthermore, at 0 months of recovery, the assimilation of photosynthetically acquired and zooplankton-feeding acquired carbon into the animal host, endosymbiont, skeleton, and coral-mediated DOC were measured via (13)C-pulse-chase labeling. During the first month of recovery, energy reserves and tissue biomass in bleached corals were maintained despite reductions in chlorophyll a, photosynthesis, and the assimilation of photosynthetically fixed carbon. At the same time, P. lobata corals catabolized carbon acquired from zooplankton and seemed to take up DOC as a source of fixed carbon. All variables that were negatively affected by bleaching recovered within 5 to 11 months. Thus, bleaching resilience in the mounding coral P. lobata is driven by its ability to actively catabolize zooplankton-acquired carbon and seemingly utilize DOC as a significant fixed carbon source, facilitating the maintenance of energy reserves and tissue biomass. With the frequency and intensity of bleaching events expected to increase over the next century, coral diversity on future reefs may favor not only mounding morphologies but species like P. lobata, which have the ability to utilize heterotrophic sources of

  5. Physiological and Biogeochemical Traits of Bleaching and Recovery in the Mounding Species of Coral Porites lobata: Implications for Resilience in Mounding Corals

    PubMed Central

    Levas, Stephen J.; Grottoli, Andréa G.; Hughes, Adam; Osburn, Christopher L.; Matsui, Yohei

    2013-01-01

    Mounding corals survive bleaching events in greater numbers than branching corals. However, no study to date has determined the underlying physiological and biogeochemical trait(s) that are responsible for mounding coral holobiont resilience to bleaching. Furthermore, the potential of dissolved organic carbon (DOC) as a source of fixed carbon to bleached corals has never been determined. Here, Porites lobata corals were experimentally bleached for 23 days and then allowed to recover for 0, 1, 5, and 11 months. At each recovery interval a suite of analyses were performed to assess their recovery (photosynthesis, respiration, chlorophyll a, energy reserves, tissue biomass, calcification, δ13C of the skeletal, δ13C, and δ15N of the animal host and endosymbiont fractions). Furthermore, at 0 months of recovery, the assimilation of photosynthetically acquired and zooplankton-feeding acquired carbon into the animal host, endosymbiont, skeleton, and coral-mediated DOC were measured via 13C-pulse-chase labeling. During the first month of recovery, energy reserves and tissue biomass in bleached corals were maintained despite reductions in chlorophyll a, photosynthesis, and the assimilation of photosynthetically fixed carbon. At the same time, P. lobata corals catabolized carbon acquired from zooplankton and seemed to take up DOC as a source of fixed carbon. All variables that were negatively affected by bleaching recovered within 5 to 11 months. Thus, bleaching resilience in the mounding coral P. lobata is driven by its ability to actively catabolize zooplankton-acquired carbon and seemingly utilize DOC as a significant fixed carbon source, facilitating the maintenance of energy reserves and tissue biomass. With the frequency and intensity of bleaching events expected to increase over the next century, coral diversity on future reefs may favor not only mounding morphologies but species like P. lobata, which have the ability to utilize heterotrophic sources of fixed carbon

  6. Bleaching Susceptibility and Recovery of Colombian Caribbean Corals in Response to Water Current Exposure and Seasonal Upwelling

    PubMed Central

    Bayraktarov, Elisa; Pizarro, Valeria; Eidens, Corvin; Wilke, Thomas; Wild, Christian

    2013-01-01

    Coral bleaching events are globally occurring more frequently and with higher intensity, mainly caused by increases in seawater temperature. In Tayrona National Natural Park (TNNP) in the Colombian Caribbean, local coral communities are subjected to seasonal wind-triggered upwelling events coinciding with stronger water currents depending on location. This natural phenomenon offers the unique opportunity to study potential water current-induced mitigation mechanisms of coral bleaching in an upwelling influenced region. Therefore, coral bleaching susceptibility and recovery patterns were compared during a moderate and a mild bleaching event in December 2010 and 2011, and at the end of the subsequent upwelling periods at a water current-exposed and -sheltered site of an exemplary bay using permanent transect and labeling tools. This was accompanied by parallel monitoring of key environmental variables. Findings revealed that in 2010 overall coral bleaching before upwelling was significantly higher at the sheltered (34%) compared to the exposed site (8%). Whereas 97% of all previously bleached corals at the water current-exposed site had recovered from bleaching by April 2011, only 77% recovered at the sheltered site, but 12% had died there. In December 2011, only mild bleaching (<10% at both sites) was observed, but corals recovered significantly at both sites in the course of upwelling. No differences in water temperatures between sites occurred, but water current exposure and turbidity were significantly higher at the exposed site, suggesting that these variables may be responsible for the observed site-specific mitigation of coral bleaching. This indicates the existence of local resilience patterns against coral bleaching in Caribbean reefs. PMID:24282551

  7. Bleaching susceptibility and recovery of Colombian Caribbean corals in response to water current exposure and seasonal upwelling.

    PubMed

    Bayraktarov, Elisa; Pizarro, Valeria; Eidens, Corvin; Wilke, Thomas; Wild, Christian

    2013-01-01

    Coral bleaching events are globally occurring more frequently and with higher intensity, mainly caused by increases in seawater temperature. In Tayrona National Natural Park (TNNP) in the Colombian Caribbean, local coral communities are subjected to seasonal wind-triggered upwelling events coinciding with stronger water currents depending on location. This natural phenomenon offers the unique opportunity to study potential water current-induced mitigation mechanisms of coral bleaching in an upwelling influenced region. Therefore, coral bleaching susceptibility and recovery patterns were compared during a moderate and a mild bleaching event in December 2010 and 2011, and at the end of the subsequent upwelling periods at a water current-exposed and -sheltered site of an exemplary bay using permanent transect and labeling tools. This was accompanied by parallel monitoring of key environmental variables. Findings revealed that in 2010 overall coral bleaching before upwelling was significantly higher at the sheltered (34%) compared to the exposed site (8%). Whereas 97% of all previously bleached corals at the water current-exposed site had recovered from bleaching by April 2011, only 77% recovered at the sheltered site, but 12% had died there. In December 2011, only mild bleaching (<10% at both sites) was observed, but corals recovered significantly at both sites in the course of upwelling. No differences in water temperatures between sites occurred, but water current exposure and turbidity were significantly higher at the exposed site, suggesting that these variables may be responsible for the observed site-specific mitigation of coral bleaching. This indicates the existence of local resilience patterns against coral bleaching in Caribbean reefs.

  8. Stable mucus-associated bacterial communities in bleached and healthy corals of Porites lobata from the Arabian Seas.

    PubMed

    Hadaidi, Ghaida; Röthig, Till; Yum, Lauren K; Ziegler, Maren; Arif, Chatchanit; Roder, Cornelia; Burt, John; Voolstra, Christian R

    2017-03-31

    Coral reefs are subject to coral bleaching manifested by the loss of endosymbiotic algae from coral host tissue. Besides algae, corals associate with bacteria. In particular, bacteria residing in the surface mucus layer are thought to mediate coral health, but their role in coral bleaching is unknown. We collected mucus from bleached and healthy Porites lobata colonies in the Persian/Arabian Gulf (PAG) and the Red Sea (RS) to investigate bacterial microbiome composition using 16S rRNA gene amplicon sequencing. We found that bacterial community structure was notably similar in bleached and healthy corals, and the most abundant bacterial taxa were identical. However, fine-scale differences in bacterial community composition between the PAG and RS were present and aligned with predicted differences in sulfur- and nitrogen-cycling processes. Based on our data, we argue that bleached corals benefit from the stable composition of mucus bacteria that resemble their healthy coral counterparts and presumably provide a conserved suite of protective functions, but monitoring of post-bleaching survival is needed to further confirm this assumption. Conversely, fine-scale site-specific differences highlight flexibility of the bacterial microbiome that may underlie adjustment to local environmental conditions and contribute to the widespread success of Porites lobata.

  9. Stable mucus-associated bacterial communities in bleached and healthy corals of Porites lobata from the Arabian Seas

    PubMed Central

    Hadaidi, Ghaida; Röthig, Till; Yum, Lauren K.; Ziegler, Maren; Arif, Chatchanit; Roder, Cornelia; Burt, John; Voolstra, Christian R.

    2017-01-01

    Coral reefs are subject to coral bleaching manifested by the loss of endosymbiotic algae from coral host tissue. Besides algae, corals associate with bacteria. In particular, bacteria residing in the surface mucus layer are thought to mediate coral health, but their role in coral bleaching is unknown. We collected mucus from bleached and healthy Porites lobata colonies in the Persian/Arabian Gulf (PAG) and the Red Sea (RS) to investigate bacterial microbiome composition using 16S rRNA gene amplicon sequencing. We found that bacterial community structure was notably similar in bleached and healthy corals, and the most abundant bacterial taxa were identical. However, fine-scale differences in bacterial community composition between the PAG and RS were present and aligned with predicted differences in sulfur- and nitrogen-cycling processes. Based on our data, we argue that bleached corals benefit from the stable composition of mucus bacteria that resemble their healthy coral counterparts and presumably provide a conserved suite of protective functions, but monitoring of post-bleaching survival is needed to further confirm this assumption. Conversely, fine-scale site-specific differences highlight flexibility of the bacterial microbiome that may underlie adjustment to local environmental conditions and contribute to the widespread success of Porites lobata. PMID:28361923

  10. Effects of modeled tropical sea surface temperature variability on coral reef bleaching predictions

    NASA Astrophysics Data System (ADS)

    van Hooidonk, R.; Huber, M.

    2012-03-01

    Future widespread coral bleaching and subsequent mortality has been projected using sea surface temperature (SST) data derived from global, coupled ocean-atmosphere general circulation models (GCMs). While these models possess fidelity in reproducing many aspects of climate, they vary in their ability to correctly capture such parameters as the tropical ocean seasonal cycle and El Niño Southern Oscillation (ENSO) variability. Such weaknesses most likely reduce the accuracy of predicting coral bleaching, but little attention has been paid to the important issue of understanding potential errors and biases, the interaction of these biases with trends, and their propagation in predictions. To analyze the relative importance of various types of model errors and biases in predicting coral bleaching, various intra- and inter-annual frequency bands of observed SSTs were replaced with those frequencies from 24 GCMs 20th century simulations included in the Intergovernmental Panel on Climate Change (IPCC) 4th assessment report. Subsequent thermal stress was calculated and predictions of bleaching were made. These predictions were compared with observations of coral bleaching in the period 1982-2007 to calculate accuracy using an objective measure of forecast quality, the Peirce skill score (PSS). Major findings are that: (1) predictions are most sensitive to the seasonal cycle and inter-annual variability in the ENSO 24-60 months frequency band and (2) because models tend to understate the seasonal cycle at reef locations, they systematically underestimate future bleaching. The methodology we describe can be used to improve the accuracy of bleaching predictions by characterizing the errors and uncertainties involved in the predictions.

  11. Differential nitric oxide synthesis and host apoptotic events correlate with bleaching susceptibility in reef corals

    NASA Astrophysics Data System (ADS)

    Hawkins, T. D.; Krueger, T.; Becker, S.; Fisher, P. L.; Davy, S. K.

    2014-03-01

    Coral bleaching poses a threat to coral reefs worldwide. As a consequence of the temperature-induced breakdown in coral-dinoflagellate symbiosis, bleaching can have extensive effects on reef communities. However, our understanding of bleaching at a cellular level is limited, and this is particularly true regarding differential susceptibility among coral species. Recent work suggests that bleaching may represent a host innate immune-like response to symbiont dysfunction that involves synthesis of the signalling compound nitric oxide (NO) and the induction of host apoptotic-like cell death. In this study, we examined the activity of apoptosis-regulating enzymes alongside oxidised NO accumulation (a proxy for NO synthesis) in the reef corals Acropora millepora, Montipora digitata, and Pocillopora damicornis during experimental thermal stress. P. damicornis was the most sensitive species, suffering mortality (tissue sloughing) after 5 days at 33 °C but non-lethal bleaching after 9 days at 31.5 °C. A. millepora bleached at 33 °C but remained structurally intact, while M. digitata showed little evidence of bleaching. P. damicornis and A. millepora both exhibited evidence of temperature-induced NO synthesis and, after 5 days of heating, levels of oxidised NO in both species were fivefold higher than in controls maintained at 28.5 °C. These responses preceded bleaching by a number of days and may have occurred before symbiont dysfunction (measured as chlorophyll a degradation and oxidised NO accumulation). In A. millepora, apparent NO synthesis correlated with the induction of host apoptotic-like pathways, while in P. damicornis, the upregulation of apoptotic pathways occurred later. No evidence of elevated NO production or apoptosis was observed in M. digitata at 33 °C and baseline activity of apoptosis-regulating enzymes was negligible in this species. These findings provide important physiological data in the context of the responses of corals to global change and

  12. Thresholds for Coral Bleaching: Are Synergistic Factors and Shifting Thresholds Changing the Landscape for Management? (Invited)

    NASA Astrophysics Data System (ADS)

    Eakin, C.; Donner, S. D.; Logan, C. A.; Gledhill, D. K.; Liu, G.; Heron, S. F.; Christensen, T.; Rauenzahn, J.; Morgan, J.; Parker, B. A.; Hoegh-Guldberg, O.; Skirving, W. J.; Strong, A. E.

    2010-12-01

    As carbon dioxide rises in the atmosphere, climate change and ocean acidification are modifying important physical and chemical parameters in the oceans with resulting impacts on coral reef ecosystems. Rising CO2 is warming the world’s oceans and causing corals to bleach, with both alarming frequency and severity. The frequent return of stressful temperatures has already resulted in major damage to many of the world’s coral reefs and is expected to continue in the foreseeable future. Warmer oceans also have contributed to a rise in coral infectious diseases. Both bleaching and infectious disease can result in coral mortality and threaten one of the most diverse ecosystems on Earth and the important ecosystem services they provide. Additionally, ocean acidification from rising CO2 is reducing the availability of carbonate ions needed by corals to build their skeletons and perhaps depressing the threshold for bleaching. While thresholds vary among species and locations, it is clear that corals around the world are already experiencing anomalous temperatures that are too high, too often, and that warming is exceeding the rate at which corals can adapt. This is despite a complex adaptive capacity that involves both the coral host and the zooxanthellae, including changes in the relative abundance of the latter in their coral hosts. The safe upper limit for atmospheric CO2 is probably somewhere below 350ppm, a level we passed decades ago, and for temperature is a sustained global temperature increase of less than 1.5°C above pre-industrial levels. How much can corals acclimate and/or adapt to the unprecedented fast changing environmental conditions? Any change in the threshold for coral bleaching as the result of acclimation and/or adaption may help corals to survive in the future but adaptation to one stress may be maladaptive to another. There also is evidence that ocean acidification and nutrient enrichment modify this threshold. What do shifting thresholds mean

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

    PubMed

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

    2015-04-01

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

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

    PubMed Central

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

    2015-01-01

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

  15. Ocean acidification causes bleaching and productivity loss in coral reef builders.

    PubMed

    Anthony, K R N; Kline, D I; Diaz-Pulido, G; Dove, S; Hoegh-Guldberg, O

    2008-11-11

    Ocean acidification represents a key threat to coral reefs by reducing the calcification rate of framework builders. In addition, acidification is likely to affect the relationship between corals and their symbiotic dinoflagellates and the productivity of this association. However, little is known about how acidification impacts on the physiology of reef builders and how acidification interacts with warming. Here, we report on an 8-week study that compared bleaching, productivity, and calcification responses of crustose coralline algae (CCA) and branching (Acropora) and massive (Porites) coral species in response to acidification and warming. Using a 30-tank experimental system, we manipulated CO(2) levels to simulate doubling and three- to fourfold increases [Intergovernmental Panel on Climate Change (IPCC) projection categories IV and VI] relative to present-day levels under cool and warm scenarios. Results indicated that high CO(2) is a bleaching agent for corals and CCA under high irradiance, acting synergistically with warming to lower thermal bleaching thresholds. We propose that CO(2) induces bleaching via its impact on photoprotective mechanisms of the photosystems. Overall, acidification impacted more strongly on bleaching and productivity than on calcification. Interestingly, the intermediate, warm CO(2) scenario led to a 30% increase in productivity in Acropora, whereas high CO(2) lead to zero productivity in both corals. CCA were most sensitive to acidification, with high CO(2) leading to negative productivity and high rates of net dissolution. Our findings suggest that sensitive reef-building species such as CCA may be pushed beyond their thresholds for growth and survival within the next few decades whereas corals will show delayed and mixed responses.

  16. Differential coral bleaching-Contrasting the activity and response of enzymatic antioxidants in symbiotic partners under thermal stress.

    PubMed

    Krueger, Thomas; Hawkins, Thomas D; Becker, Susanne; Pontasch, Stefanie; Dove, Sophie; Hoegh-Guldberg, Ove; Leggat, William; Fisher, Paul L; Davy, Simon K

    2015-12-01

    Mass coral bleaching due to thermal stress represents a major threat to the integrity and functioning of coral reefs. Thermal thresholds vary, however, between corals, partly as a result of the specific type of endosymbiotic dinoflagellate (Symbiodinium sp.) they harbour. The production of reactive oxygen species (ROS) in corals under thermal and light stress has been recognised as one mechanism that can lead to cellular damage and the loss of their symbiont population (Oxidative Theory of Coral Bleaching). Here, we compared the response of symbiont and host enzymatic antioxidants in the coral species Acropora millepora and Montipora digitata at 28°C and 33°C. A. millepora at 33°C showed a decrease in photochemical efficiency of photosystem II (PSII) and increase in maximum midday excitation pressure on PSII, with subsequent bleaching (declining photosynthetic pigment and symbiont density). M. digitata exhibited no bleaching response and photochemical changes in its symbionts were minor. The symbiont antioxidant enzymes superoxide dismutase, ascorbate peroxidase, and catalase peroxidase showed no significant upregulation to elevated temperatures in either coral, while only catalase was significantly elevated in both coral hosts at 33°C. Increased host catalase activity in the susceptible coral after 5days at 33°C was independent of antioxidant responses in the symbiont and preceded significant declines in PSII photochemical efficiencies. This finding suggests a potential decoupling of host redox mechanisms from symbiont photophysiology and raises questions about the importance of symbiont-derived ROS in initiating coral bleaching.

  17. Coral bleaching: one disturbance too many for near-shore reefs of the Great Barrier Reef

    NASA Astrophysics Data System (ADS)

    Thompson, A. A.; Dolman, A. M.

    2010-09-01

    The dynamic nature of coral communities can make it difficult to judge whether a reef system is resilient to the current disturbance regime. To address this question of resilience for near-shore coral communities of the Great Barrier Reef (Australia) a data set consisting of 350 annual observations of benthic community change was compiled from existing monitoring data. These data spanned the period 1985-2007 and were derived from coral reefs within 20 km of the coast. During years without major disturbance events, cover increase of the Acroporidae was much faster than it was for other coral families; a median of 11% per annum compared to medians of less than 4% for other coral families. Conversely, Acroporidae were more severely affected by cyclones and bleaching events than most other families. A simulation model parameterised with these observations indicated that while recovery rates of hard corals were sufficient to compensate for impacts associated with cyclones and crown-of-thorns starfish, the advent of mass bleaching has lead to a significant change in the composition of the community and a rapid decline in hard coral cover. Furthermore, if bleaching events continue to occur with the same frequency and severity as in the recent past, the model predicts that the cover of Acroporidae will continue to decline. Although significant cover of live coral remains on near-shore reefs, and recovery is observed during inter-disturbance periods, it appears that this system will not be resilient to the recent disturbance regime over the long term. Conservation strategies for coral reefs should focus on both mitigating local factors that act synergistically to increase the susceptibility of Acroporidae to climate change while promoting initiatives that maximise the recovery potential from inevitable disturbances.

  18. The northern limit of corals of the genus Acropora in temperate zones is determined by their resilience to cold bleaching.

    PubMed

    Higuchi, Tomihiko; Agostini, Sylvain; Casareto, Beatriz Estela; Suzuki, Yoshimi; Yuyama, Ikuko

    2015-12-18

    The distribution of corals in Japan covers a wide range of latitudes, encompassing tropical to temperate zones. However, coral communities in temperate zones contain only a small subset of species. Among the parameters that determine the distribution of corals, temperature plays an important role. We tested the resilience to cold stress of three coral species belonging to the genus Acropora in incubation experiments. Acropora pruinosa, which is the northernmost of the three species, bleached at 13 °C, but recovered once temperatures were increased. The two other species, A. hyacinthus and A. solitaryensis, which has a more southerly range than A. pruinosa, died rapidly after bleaching at 13 °C. The physiological effects of cold bleaching on the corals included decreased rates of photosynthesis, respiration, and calcification, similar to the physiological effects observed with bleaching due to high temperature stress. Contrasting hot bleaching, no increases in antioxidant enzyme activities were observed, suggesting that reactive oxygen species play a less important role in bleaching under cold stress. These results confirmed the importance of resilience to cold stress in determining the distribution and northern limits of coral species, as cold events causing coral bleaching and high mortality occur regularly in temperate zones.

  19. The northern limit of corals of the genus Acropora in temperate zones is determined by their resilience to cold bleaching

    PubMed Central

    Higuchi, Tomihiko; Agostini, Sylvain; Casareto, Beatriz Estela; Suzuki, Yoshimi; Yuyama, Ikuko

    2015-01-01

    The distribution of corals in Japan covers a wide range of latitudes, encompassing tropical to temperate zones. However, coral communities in temperate zones contain only a small subset of species. Among the parameters that determine the distribution of corals, temperature plays an important role. We tested the resilience to cold stress of three coral species belonging to the genus Acropora in incubation experiments. Acropora pruinosa, which is the northernmost of the three species, bleached at 13 °C, but recovered once temperatures were increased. The two other species, A. hyacinthus and A. solitaryensis, which has a more southerly range than A. pruinosa, died rapidly after bleaching at 13 °C. The physiological effects of cold bleaching on the corals included decreased rates of photosynthesis, respiration, and calcification, similar to the physiological effects observed with bleaching due to high temperature stress. Contrasting hot bleaching, no increases in antioxidant enzyme activities were observed, suggesting that reactive oxygen species play a less important role in bleaching under cold stress. These results confirmed the importance of resilience to cold stress in determining the distribution and northern limits of coral species, as cold events causing coral bleaching and high mortality occur regularly in temperate zones. PMID:26680690

  20. PREDICTING CORAL BLEACHING IN RESPONSE TO ENVIRONMENTAL STRESSORS USING 8 YEARS OF GLOBAL-SCALE DATA.

    EPA Science Inventory

    Coral reefs are among the most diverse marine ecosystems on the planet (Wilkinson 2002), but have experienced extensive mortality over the past few decades as a result of mass bleaching events (Hoegh-Guldberg 1999, Wilkinson 2002, Hughes 2003, Obura 2005). Historically, elevated...

  1. Predicting coral bleaching hotspots: the role of regional variability in thermal stress and potential adaptation rates

    NASA Astrophysics Data System (ADS)

    Teneva, Lida; Karnauskas, Mandy; Logan, Cheryl A.; Bianucci, Laura; Currie, Jock C.; Kleypas, Joan A.

    2012-03-01

    Sea surface temperature fields (1870-2100) forced by CO2-induced climate change under the IPCC SRES A1B CO2 scenario, from three World Climate Research Programme Coupled Model Intercomparison Project Phase 3 (WCRP CMIP3) models (CCSM3, CSIRO MK 3.5, and GFDL CM 2.1), were used to examine how coral sensitivity to thermal stress and rates of adaption affect global projections of coral-reef bleaching. The focus of this study was two-fold, to: (1) assess how the impact of Degree-Heating-Month (DHM) thermal stress threshold choice affects potential bleaching predictions and (2) examine the effect of hypothetical adaptation rates of corals to rising temperature. DHM values were estimated using a conventional threshold of 1°C and a variability-based threshold of 2σ above the climatological maximum Coral adaptation rates were simulated as a function of historical 100-year exposure to maximum annual SSTs with a dynamic rather than static climatological maximum based on the previous 100 years, for a given reef cell. Within CCSM3 simulations, the 1°C threshold predicted later onset of mild bleaching every 5 years for the fraction of reef grid cells where 1°C > 2σ of the climatology time series of annual SST maxima (1961-1990). Alternatively, DHM values using both thresholds, with CSIRO MK 3.5 and GFDL CM 2.1 SSTs, did not produce drastically different onset timing for bleaching every 5 years. Across models, DHMs based on 1°C thermal stress threshold show the most threatened reefs by 2100 could be in the Central and Western Equatorial Pacific, whereas use of the variability-based threshold for DHMs yields the Coral Triangle and parts of Micronesia and Melanesia as bleaching hotspots. Simulations that allow corals to adapt to increases in maximum SST drastically reduce the rates of bleaching. These findings highlight the importance of considering the thermal stress threshold in DHM estimates as well as potential adaptation models in future coral bleaching projections.

  2. Surviving Coral Bleaching Events: Porites Growth Anomalies on the Great Barrier Reef

    PubMed Central

    Cantin, Neal E.; Lough, Janice M.

    2014-01-01

    Mass coral bleaching affected large parts of the Great Barrier Reef (GBR) in 1998 and 2002. In this study, we assessed if signatures of these major thermal stress events were recorded in the growth characteristics of massive Porites colonies. In 2005 a suite of short (<50 cm) cores were collected from apparently healthy, surviving Porites colonies, from reefs in the central GBR (18–19°S) that have documented observations of widespread bleaching. Sites included inshore (Nelly Bay, Pandora Reef), annually affected by freshwater flood events, midshelf (Rib Reef), only occasionally affected by freshwater floods and offshore (Myrmidon Reef) locations primarily exposed to open ocean conditions. Annual growth characteristics (extension, density and calcification) were measured in 144 cores from 79 coral colonies and analysed over the common 24-year period, 1980–2003. Visual examination of the annual density bands revealed growth hiatuses associated with the bleaching years in the form of abrupt decreases in annual linear extension rates, high density stress bands and partial mortality. The 1998 mass-bleaching event reduced Porites calcification by 13 and 18% on the two inshore locations for 4 years, followed by recovery to baseline calcification rates in 2002. Evidence of partial mortality was apparent in 10% of the offshore colonies in 2002; however no significant effects of the bleaching events were evident in the calcification rates at the mid shelf and offshore sites. These results highlight the spatial variation of mass bleaching events and that all reef locations within the GBR were not equally stressed by the 1998 and 2002 mass bleaching events, as some models tend to suggest, which enabled recovery of calcification on the GBR within 4 years. The dynamics in annual calcification rates and recovery displayed here should be used to improve model outputs that project how coral calcification will respond to ongoing warming of the tropical oceans. PMID:24586377

  3. Surviving coral bleaching events: porites growth anomalies on the Great Barrier Reef.

    PubMed

    Cantin, Neal E; Lough, Janice M

    2014-01-01

    Mass coral bleaching affected large parts of the Great Barrier Reef (GBR) in 1998 and 2002. In this study, we assessed if signatures of these major thermal stress events were recorded in the growth characteristics of massive Porites colonies. In 2005 a suite of short (<50 cm) cores were collected from apparently healthy, surviving Porites colonies, from reefs in the central GBR (18-19°S) that have documented observations of widespread bleaching. Sites included inshore (Nelly Bay, Pandora Reef), annually affected by freshwater flood events, midshelf (Rib Reef), only occasionally affected by freshwater floods and offshore (Myrmidon Reef) locations primarily exposed to open ocean conditions. Annual growth characteristics (extension, density and calcification) were measured in 144 cores from 79 coral colonies and analysed over the common 24-year period, 1980-2003. Visual examination of the annual density bands revealed growth hiatuses associated with the bleaching years in the form of abrupt decreases in annual linear extension rates, high density stress bands and partial mortality. The 1998 mass-bleaching event reduced Porites calcification by 13 and 18% on the two inshore locations for 4 years, followed by recovery to baseline calcification rates in 2002. Evidence of partial mortality was apparent in 10% of the offshore colonies in 2002; however no significant effects of the bleaching events were evident in the calcification rates at the mid shelf and offshore sites. These results highlight the spatial variation of mass bleaching events and that all reef locations within the GBR were not equally stressed by the 1998 and 2002 mass bleaching events, as some models tend to suggest, which enabled recovery of calcification on the GBR within 4 years. The dynamics in annual calcification rates and recovery displayed here should be used to improve model outputs that project how coral calcification will respond to ongoing warming of the tropical oceans.

  4. Differential thermal bleaching susceptibilities amongst coral taxa: re-posing the role of the host

    NASA Astrophysics Data System (ADS)

    Wooldridge, Scott A.

    2014-03-01

    It is well established that different coral species have different susceptibilities to thermal stress, yet it is less clear which biological or physical mechanisms allow some corals to resist thermal stress, whereas other corals bleach and die. Although the type of symbiont is clearly of fundamental importance, many aspects of coral bleaching cannot be explained solely by differences in symbionts amongst coral species. Here, I use the CO2 (sink) limitation model of coral bleaching to repose various host traits believed to influence thermal tolerance (e.g. metabolic rates, colony tissue thickness, skeletal growth form, mucus production rates, tissue concentration of fluorescent pigments and heterotrophic feedings capacity) in terms of an integrated strategy to reduce the likelihood of CO2 limitation around its intracellular photosymbionts. Contrasting observational data for the skeletal vital effect on oxygen isotope composition (δ18O) partitions two alternate evolutionary strategies. The first strategy is heavily reliant on a sea water supply chain of CO2 to supplement respiratory CO2(met). In contrast, the alternate strategy is less reliant on the sea water supply source, potentially facilitated by increased basal respiration rates and/or a lower photosynthetic demand for CO2. The comparative vulnerability of these alternative strategies to modern ocean conditions is used to explain the global-wide observation that corals with branching morphologies (and thin tissue layers) are generally more thermally sensitive than corals with massive morphologies (and thick tissue layers). The life history implications of this new framework are discussed in terms of contrasting fitness drivers and past environmental constraints, which delivers ominous predictions for the viability of thin-tissued branching and plating species during the present human-dominated ("Anthropocene") era of the Earth System.

  5. Coral Diseases Following Massive Bleaching in 2005 Cause 60 Percent Decline in Coral Cover and Mortality of the Threatened Species, Acropora Palmata, on Reefs in the U.S. Virgin Islands

    USGS Publications Warehouse

    Rogers, Caroline S.

    2008-01-01

    Record-high seawater temperatures and calm seas in the summer of 2005 led to the most severe coral bleaching (greater than 90 percent bleached coral cover) ever observed in the U.S. Virgin Islands (USVI) (figs. 1 and 2). All but a few coral species bleached, including the threatened species, Acropora palmata. Bleaching was seen from the surface to depths over 20 meters.

  6. Tracking the Effect of Algal Mats on Coral Bleaching Using Remote Sensing

    NASA Astrophysics Data System (ADS)

    El-Askary, H. M.; Johnson, S. H.; Idris, N.; Qurban, M. A. B.

    2014-12-01

    Benthic habitats rely on relatively stable environmental conditions for survival. The introduction of algal mats into an ecosystem can have a notable effect on the livelihood of organisms such as coral reefs by causing changes in the biogeochemistry of the surrounding water. Increasing levels of acidity and new competition for sunlight caused by congregations of cyanobacteria essentially starve coral reefs of natural resources. These changes are particularly prevalent in waters near quickly developing population centers, such as the ecologically diverse Arabian Gulf. While ground-truthing studies to determine the extensiveness of coral death proves useful on a microcosmic level, new ventures in remote sensing research allow scientists to utilize satellite data to track these changes on a broader scale. Satellite images acquired from Landsat 5, 1987, Landsat 7, 2000, and Landsat 8, 2013 along with higher resolution IKONOS data are digitally analyzed in order to create spectral libraries for relevant benthic types, which in turn can be used to perform supervised classifications and change detection analyses over a larger area. The supervised classifications performed over the three scenes show five significant marine-related classes, namely coral, mangroves, macro-algae, and seagrass, in different degrees of abundance, yet here we focus only on the algal mats impact on corals bleaching. The change detection analysis is introduced to study see the degree of algal mats impact on coral bleaching over the course of time with possible connection to the local meteorology and current climate scenarios.

  7. Climate change and coral reef bleaching: An ecological assessment of long-term impacts, recovery trends and future outlook

    NASA Astrophysics Data System (ADS)

    Baker, Andrew C.; Glynn, Peter W.; Riegl, Bernhard

    2008-12-01

    Since the early 1980s, episodes of coral reef bleaching and mortality, due primarily to climate-induced ocean warming, have occurred almost annually in one or more of the world's tropical or subtropical seas. Bleaching is episodic, with the most severe events typically accompanying coupled ocean-atmosphere phenomena, such as the El Niño-Southern Oscillation (ENSO), which result in sustained regional elevations of ocean temperature. Using this extended dataset (25+ years), we review the short- and long-term ecological impacts of coral bleaching on reef ecosystems, and quantitatively synthesize recovery data worldwide. Bleaching episodes have resulted in catastrophic loss of coral cover in some locations, and have changed coral community structure in many others, with a potentially critical influence on the maintenance of biodiversity in the marine tropics. Bleaching has also set the stage for other declines in reef health, such as increases in coral diseases, the breakdown of reef framework by bioeroders, and the loss of critical habitat for associated reef fishes and other biota. Secondary ecological effects, such as the concentration of predators on remnant surviving coral populations, have also accelerated the pace of decline in some areas. Although bleaching severity and recovery have been variable across all spatial scales, some reefs have experienced relatively rapid recovery from severe bleaching impacts. There has been a significant overall recovery of coral cover in the Indian Ocean, where many reefs were devastated by a single large bleaching event in 1998. In contrast, coral cover on western Atlantic reefs has generally continued to decline in response to multiple smaller bleaching events and a diverse set of chronic secondary stressors. No clear trends are apparent in the eastern Pacific, the central-southern-western Pacific or the Arabian Gulf, where some reefs are recovering and others are not. The majority of survivors and new recruits on

  8. Ocean acidification has no effect on thermal bleaching in the coral Seriatopora caliendrum

    NASA Astrophysics Data System (ADS)

    Wall, C. B.; Fan, T.-Y.; Edmunds, P. J.

    2014-03-01

    The objective of this study was to test whether elevated pCO2 predicted for the year 2100 (85.1 Pa) affects bleaching in the coral Seriatopora caliendrum (Ehrenberg 1834) either independently or interactively with high temperature (30.5 °C). Response variables detected the sequence of events associated with the onset of bleaching: reduction in the photosynthetic performance of symbionts as measured by maximum photochemical efficiency ( F v/ F m) and effective photochemical efficiency (Δ F/ F m') of PSII, declines in net photosynthesis ( P net) and photosynthetic efficiency (alpha, α), and finally, reduced chlorophyll a and symbiont concentrations. S. caliendrum was collected from Nanwan Bay, Taiwan, and subjected to combinations of temperature (27.7 vs. 30.5 °C) and pCO2 (45.1 vs. 85.1 Pa) for 14 days. High temperature reduced values of all dependent variables (i.e., bleaching occurred), but high pCO2 did not affect Symbiodinium photophysiology or productivity, and did not cause bleaching. These results suggest that short-term exposure to 81.5 Pa pCO2, alone and in combination with elevated temperature, does not cause or affect coral bleaching.

  9. "Super-quenching" state protects Symbiodinium from thermal stress - Implications for coral bleaching.

    PubMed

    Slavov, Chavdar; Schrameyer, Verena; Reus, Michael; Ralph, Peter J; Hill, Ross; Büchel, Claudia; Larkum, Anthony W D; Holzwarth, Alfred R

    2016-06-01

    The global rise in sea surface temperatures causes regular exposure of corals to high temperature and high light stress, leading to worldwide disastrous coral bleaching events (loss of symbiotic dinoflagellates (Symbiodinium) from reef-building corals). Our picosecond chlorophyll fluorescence experiments on cultured Symbiodinium clade C cells exposed to coral bleaching conditions uncovered the transformations of the alga's photosynthetic apparatus (PSA) that activate an extremely efficient non-photochemical "super-quenching" mechanism. The mechanism is associated with a transition from an initially heterogeneous photosystem II (PSII) pool to a homogeneous "spillover" pool, where nearly all excitation energy is transferred to photosystem I (PSI). There, the inherently higher stability of PSI and high quenching efficiency of P(700)(+) allow dumping of PSII excess excitation energy into heat, resulting in almost complete cessation of photosynthetic electron transport (PET). This potentially reversible "super-quenching" mechanism protects the PSA against destruction at the cost of a loss of photosynthetic activity. We suggest that the inhibition of PET and the consequent inhibition of organic carbon production (e.g. sugars) in the symbiotic Symbiodinium provide a trigger for the symbiont expulsion, i.e. bleaching.

  10. Transient turbid water mass reduces temperature-induced coral bleaching and mortality in Barbados.

    PubMed

    Oxenford, Hazel A; Vallès, Henri

    2016-01-01

    Global warming is seen as one of the greatest threats to the world's coral reefs and, with the continued rise in sea surface temperature predicted into the future, there is a great need for further understanding of how to prevent and address the damaging impacts. This is particularly so for countries whose economies depend heavily on healthy reefs, such as those of the eastern Caribbean. Here, we compare the severity of bleaching and mortality for five dominant coral species at six representative reef sites in Barbados during the two most significant warm-water events ever recorded in the eastern Caribbean, i.e., 2005 and 2010, and describe prevailing island-scale sea water conditions during both events. In so doing, we demonstrate that coral bleaching and subsequent mortality were considerably lower in 2010 than in 2005 for all species, irrespective of site, even though the anomalously warm water temperature profiles were very similar between years. We also show that during the 2010 event, Barbados was engulfed by a transient dark green turbid water mass of riverine origin coming from South America. We suggest that reduced exposure to high solar radiation associated with this transient water mass was the primary contributing factor to the lower bleaching and mortality observed in all corals. We conclude that monitoring these episodic mesoscale oceanographic features might improve risk assessments of southeastern Caribbean reefs to warm-water events in the future.

  11. Transient turbid water mass reduces temperature-induced coral bleaching and mortality in Barbados

    PubMed Central

    Vallès, Henri

    2016-01-01

    Global warming is seen as one of the greatest threats to the world’s coral reefs and, with the continued rise in sea surface temperature predicted into the future, there is a great need for further understanding of how to prevent and address the damaging impacts. This is particularly so for countries whose economies depend heavily on healthy reefs, such as those of the eastern Caribbean. Here, we compare the severity of bleaching and mortality for five dominant coral species at six representative reef sites in Barbados during the two most significant warm-water events ever recorded in the eastern Caribbean, i.e., 2005 and 2010, and describe prevailing island-scale sea water conditions during both events. In so doing, we demonstrate that coral bleaching and subsequent mortality were considerably lower in 2010 than in 2005 for all species, irrespective of site, even though the anomalously warm water temperature profiles were very similar between years. We also show that during the 2010 event, Barbados was engulfed by a transient dark green turbid water mass of riverine origin coming from South America. We suggest that reduced exposure to high solar radiation associated with this transient water mass was the primary contributing factor to the lower bleaching and mortality observed in all corals. We conclude that monitoring these episodic mesoscale oceanographic features might improve risk assessments of southeastern Caribbean reefs to warm-water events in the future. PMID:27326377

  12. Model-based assessment of the role of human-induced climate change in the 2005 Caribbean coral bleaching event.

    PubMed

    Donner, Simon D; Knutson, Thomas R; Oppenheimer, Michael

    2007-03-27

    Episodes of mass coral bleaching around the world in recent decades have been attributed to periods of anomalously warm ocean temperatures. In 2005, the sea surface temperature (SST) anomaly in the tropical North Atlantic that may have contributed to the strong hurricane season caused widespread coral bleaching in the Eastern Caribbean. Here, we use two global climate models to evaluate the contribution of natural climate variability and anthropogenic forcing to the thermal stress that caused the 2005 coral bleaching event. Historical temperature data and simulations for the 1870-2000 period show that the observed warming in the region is unlikely to be due to unforced climate variability alone. Simulation of background climate variability suggests that anthropogenic warming may have increased the probability of occurrence of significant thermal stress events for corals in this region by an order of magnitude. Under scenarios of future greenhouse gas emissions, mass coral bleaching in the Eastern Caribbean may become a biannual event in 20-30 years. However, if corals and their symbionts can adapt by 1-1.5 degrees C, such mass bleaching events may not begin to recur at potentially harmful intervals until the latter half of the century. The delay could enable more time to alter the path of greenhouse gas emissions, although long-term "committed warming" even after stabilization of atmospheric CO(2) levels may still represent an additional long-term threat to corals.

  13. Model-based assessment of the role of human-induced climate change in the 2005 Caribbean coral bleaching event

    SciTech Connect

    Donner, S.D.; Knutson, T.R.; Oppenheimer, M.

    2007-03-27

    Episodes of mass coral bleaching around the world in recent decades have been attributed to periods of anomalously warm ocean temperatures. In 2005, the sea surface temperature (SST) anomaly in the tropical North Atlantic that may have contributed to the strong hurricane season caused widespread coral bleaching in the Eastern Caribbean. Here, the authors use two global climate models to evaluate the contribution of natural climate variability and anthropogenic forcing to the thermal stress that caused the 2005 coral bleaching event. Historical temperature data and simulations for the 1870-2000 period show that the observed warming in the region is unlikely to be due to unforced climate variability alone. Simulation of background climate variability suggests that anthropogenic warming may have increased the probability of occurrence of significant thermal stress events for corals in this region by an order of magnitude. Under scenarios of future greenhouse gas emissions, mass coral bleaching in the Eastern Caribbean may become a biannual event in 20-30 years. However, if corals and their symbionts can adapt by 1-1.5{sup o}C, such mass bleaching events may not begin to recur at potentially harmful intervals until the latter half of the century. The delay could enable more time to alter the path of greenhouse gas emissions, although long-term 'committed warming' even after stabilization of atmospheric CO{sub 2} levels may still represent an additional long-term threat to corals.

  14. A change in coral extension rates and stable isotopes after El Niño-induced coral bleaching and regional stress events

    NASA Astrophysics Data System (ADS)

    Hetzinger, S.; Pfeiffer, M.; Dullo, W.-Chr.; Zinke, J.; Garbe-Schönberg, D.

    2016-09-01

    Coral reefs are biologically diverse ecosystems threatened with effective collapse under rapid climate change, in particular by recent increases in ocean temperatures. Coral bleaching has occurred during major El Niño warming events, at times leading to the die-off of entire coral reefs. Here we present records of stable isotopic composition, Sr/Ca ratios and extension rate (1940–2004) in coral aragonite from a northern Venezuelan site, where reefs were strongly impacted by bleaching following the 1997–98 El Niño. We assess the impact of past warming events on coral extension rates and geochemical proxies. A marked decrease in coral (Pseudodiploria strigosa) extension rates coincides with a baseline shift to more negative values in oxygen and carbon isotopic composition after 1997–98, while a neighboring coral (Siderastrea siderea) recovered to pre-bleaching extension rates simultaneously. However, other stressors, besides high temperature, might also have influenced coral physiology and geochemistry. Coastal Venezuelan reefs were exposed to a series of extreme environmental fluctuations since the mid-1990s, i.e. upwelling, extreme rainfall and sediment input from landslides. This work provides important new data on the potential impacts of multiple regional stress events on coral isotopic compositions and raises questions about the long-term influence on coral-based paleoclimate reconstructions.

  15. A change in coral extension rates and stable isotopes after El Niño-induced coral bleaching and regional stress events.

    PubMed

    Hetzinger, S; Pfeiffer, M; Dullo, W-Chr; Zinke, J; Garbe-Schönberg, D

    2016-09-13

    Coral reefs are biologically diverse ecosystems threatened with effective collapse under rapid climate change, in particular by recent increases in ocean temperatures. Coral bleaching has occurred during major El Niño warming events, at times leading to the die-off of entire coral reefs. Here we present records of stable isotopic composition, Sr/Ca ratios and extension rate (1940-2004) in coral aragonite from a northern Venezuelan site, where reefs were strongly impacted by bleaching following the 1997-98 El Niño. We assess the impact of past warming events on coral extension rates and geochemical proxies. A marked decrease in coral (Pseudodiploria strigosa) extension rates coincides with a baseline shift to more negative values in oxygen and carbon isotopic composition after 1997-98, while a neighboring coral (Siderastrea siderea) recovered to pre-bleaching extension rates simultaneously. However, other stressors, besides high temperature, might also have influenced coral physiology and geochemistry. Coastal Venezuelan reefs were exposed to a series of extreme environmental fluctuations since the mid-1990s, i.e. upwelling, extreme rainfall and sediment input from landslides. This work provides important new data on the potential impacts of multiple regional stress events on coral isotopic compositions and raises questions about the long-term influence on coral-based paleoclimate reconstructions.

  16. A change in coral extension rates and stable isotopes after El Niño-induced coral bleaching and regional stress events

    PubMed Central

    Hetzinger, S.; Pfeiffer, M.; Dullo, W.-Chr.; Zinke, J.; Garbe-Schönberg, D.

    2016-01-01

    Coral reefs are biologically diverse ecosystems threatened with effective collapse under rapid climate change, in particular by recent increases in ocean temperatures. Coral bleaching has occurred during major El Niño warming events, at times leading to the die-off of entire coral reefs. Here we present records of stable isotopic composition, Sr/Ca ratios and extension rate (1940–2004) in coral aragonite from a northern Venezuelan site, where reefs were strongly impacted by bleaching following the 1997–98 El Niño. We assess the impact of past warming events on coral extension rates and geochemical proxies. A marked decrease in coral (Pseudodiploria strigosa) extension rates coincides with a baseline shift to more negative values in oxygen and carbon isotopic composition after 1997–98, while a neighboring coral (Siderastrea siderea) recovered to pre-bleaching extension rates simultaneously. However, other stressors, besides high temperature, might also have influenced coral physiology and geochemistry. Coastal Venezuelan reefs were exposed to a series of extreme environmental fluctuations since the mid-1990s, i.e. upwelling, extreme rainfall and sediment input from landslides. This work provides important new data on the potential impacts of multiple regional stress events on coral isotopic compositions and raises questions about the long-term influence on coral-based paleoclimate reconstructions. PMID:27619506

  17. Comparisons of the 1995 and 1998 coral bleaching events on the patch reefs of San Salvador Island, Bahamas.

    PubMed

    McGrath, Thomas A; Smith, Garriet W

    2003-06-01

    Coral patch reefs around San Salvador Island, Bahamas have been monitored with the aid of Earthwatch volunteers three times a year since 1992. During that period two significant mass bleaching events occurred: autumn 1995, and late summer 1998. Elsewhere in 1995, bleaching was caused by higher-than-normal summer sea temperatures; in San Salvador, however, temperatures were normal. In 1998 a prolonged period of higher-than-normal sea temperatures preceded bleaching on San Salvador and worldwide. During the 1995 event, one of the monitored reefs had twice the percentage of coral colonies bleached as the other two. Bleaching was more evenly distributed among the reefs during the 1998 event. In 1995 Agaricia agaricites was significantly more affected than other coral species, with almost 50% of all its colonies showing bleaching. Bleaching was more evenly spread among coral species in 1998, with five species showing bleaching on more than 40% of their colonies. Bleaching began on Millepora as early as August during the 1998 event and progressed to other species through the remainder of the autumn. In 1995 bleaching was not seen until late autumn and appeared to impact all affected species at about the same time. Recovery from the 1995 event was complete: no coral death or damage above normal background levels were seen. In the 1998 event, all Acropora cervicornis on the monitored reefs died and A. palmata was severely damaged. Millepora sp. lost almost half of their live tissue, and Montastraea sp. showed significant tissue damage following this event. Phototransect analysis suggests that more than 20% of total live tissue on affected species died during the 1998 event. A. cervicornis has demonstrated no re-growth from 1998 to 2000 on monitored reefs. Monitoring has suggested significant differences in causes and courses in these two events.

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

    PubMed

    Seneca, Francois O; Palumbi, Stephen R

    2015-04-01

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

  19. Change in algal symbiont communities after bleaching, not prior heat exposure, increases heat tolerance of reef corals.

    PubMed

    Silverstein, Rachel N; Cunning, Ross; Baker, Andrew C

    2015-01-01

    Mutualistic organisms can be particularly susceptible to climate change stress, as their survivorship is often limited by the most vulnerable partner. However, symbiotic plasticity can also help organisms in changing environments by expanding their realized niche space. Coral-algal (Symbiodinium spp.) symbiosis exemplifies this dichotomy: the partnership is highly susceptible to 'bleaching' (stress-induced symbiosis breakdown), but stress-tolerant symbionts can also sometimes mitigate bleaching. Here, we investigate the role of diverse and mutable symbiotic partnerships in increasing corals' ability to thrive in high temperature conditions. We conducted repeat bleaching and recovery experiments on the coral Montastraea cavernosa, and used quantitative PCR and chlorophyll fluorometry to assess the structure and function of Symbiodinium communities within coral hosts. During an initial heat exposure (32 °C for 10 days), corals hosting only stress-sensitive symbionts (Symbiodinium C3) bleached, but recovered (at either 24 °C or 29 °C) with predominantly (>90%) stress-tolerant symbionts (Symbiodinium D1a), which were not detected before bleaching (either due to absence or extreme low abundance). When a second heat stress (also 32 °C for 10 days) was applied 3 months later, corals that previously bleached and were now dominated by D1a Symbiodinium experienced less photodamage and symbiont loss compared to control corals that had not been previously bleached, and were therefore still dominated by Symbiodinium C3. Additional corals that were initially bleached without heat by a herbicide (DCMU, at 24 °C) also recovered predominantly with D1a symbionts, and similarly lost fewer symbionts during subsequent thermal stress. Increased thermotolerance was also not observed in C3-dominated corals that were acclimated for 3 months to warmer temperatures (29 °C) before heat stress. These findings indicate that increased thermotolerance post-bleaching resulted from

  20. Metabolite profiling of symbiont and host during thermal stress and bleaching in the coral Acropora aspera

    NASA Astrophysics Data System (ADS)

    Hillyer, Katie E.; Dias, Daniel A.; Lutz, Adrian; Wilkinson, Shaun P.; Roessner, Ute; Davy, Simon K.

    2017-03-01

    Rising seawater temperatures pose a significant threat to the persistence of coral reefs. Despite the importance of these systems, major gaps remain in our understanding of how thermal stress and bleaching affect the metabolic networks that underpin holobiont function. We applied gas chromatography-mass spectrometry (GC-MS) metabolomics to detect changes in the intracellular free metabolite pools (polar and semi-polar compounds) of in hospite dinoflagellate symbionts and their coral hosts (and any associated microorganisms) during early- and late-stage thermal bleaching (a reduction of approximately 50 and 70% in symbiont density, respectively). We detected characteristic changes to the metabolite profiles of each symbiotic partner associated with individual cellular responses to thermal, oxidative and osmotic stress, which progressed with the severity of bleaching. Alterations were also indicative of changes to energy-generating and biosynthesis pathways in both partners, with a shift to the increased catabolism of lipid stores. Specifically, in symbiont intracellular metabolite pools, we observed accumulations of multiple free fatty acids, plus the chloroplast-associated antioxidant alpha-tocopherol. In the host, we detected a decline in the abundance of pools of multiple carbohydrates, amino acids and intermediates, in addition to the antioxidant ascorbate. These findings further our understanding of the metabolic changes that occur to symbiont and host (and its associated microorganisms) during thermal bleaching. These findings also provide further insight into the largely undescribed roles of free metabolite pools in cellular homeostasis, signalling and acclimation to thermal stress in the cnidarian-dinoflagellate symbiosis.

  1. Depth-dependent mortality of reef corals following a severe bleaching event: implications for thermal refuges and population recovery.

    PubMed

    Bridge, Tom C L; Hoey, Andrew S; Campbell, Stuart J; Muttaqin, Efin; Rudi, Edi; Fadli, Nur; Baird, Andrew H

    2013-01-01

    Coral bleaching caused by rising sea temperature is a primary cause of coral reef degradation. However, bleaching patterns often show significant spatial variability, therefore identifying locations where local conditions may provide thermal refuges is a high conservation priority. Coral bleaching mortality often diminishes with increasing depth, but clear depth zonation of coral communities and putative limited overlap in species composition between deep and shallow reef habitats has led to the conclusion that deeper reef habitats will provide limited refuge from bleaching for most species. Here, we show that coral mortality following a severe bleaching event diminished sharply with depth. Bleaching-induced mortality of Acropora was approximately 90% at 0-2m, 60% at 3-4 m, yet at 6-8m there was negligible mortality. Importantly, at least two-thirds of the shallow-water (2-3 m) Acropora assemblage had a depth range that straddled the transition from high to low mortality. Cold-water upwelling may have contributed to the lower mortality observed in all but the shallowest depths. Our results demonstrate that, in this instance, depth provided a refuge for individuals from a high proportion of species in this Acropora-dominated assemblage. The persistence of deeper populations may provide a critical source of propagules to assist recovery of adjacent shallow-water reefs.

  2. Coral bleaching under thermal stress: putative involvement of host/symbiont recognition mechanisms

    PubMed Central

    Vidal-Dupiol, Jeremie; Adjeroud, Mehdi; Roger, Emmanuel; Foure, Laurent; Duval, David; Mone, Yves; Ferrier-Pages, Christine; Tambutte, Eric; Tambutte, Sylvie; Zoccola, Didier; Allemand, Denis; Mitta, Guillaume

    2009-01-01

    Background Coral bleaching can be defined as the loss of symbiotic zooxanthellae and/or their photosynthetic pigments from their cnidarian host. This major disturbance of reef ecosystems is principally induced by increases in water temperature. Since the beginning of the 1980s and the onset of global climate change, this phenomenon has been occurring at increasing rates and scales, and with increasing severity. Several studies have been undertaken in the last few years to better understand the cellular and molecular mechanisms of coral bleaching but the jigsaw puzzle is far from being complete, especially concerning the early events leading to symbiosis breakdown. The aim of the present study was to find molecular actors involved early in the mechanism leading to symbiosis collapse. Results In our experimental procedure, one set of Pocillopora damicornis nubbins was subjected to a gradual increase of water temperature from 28°C to 32°C over 15 days. A second control set kept at constant temperature (28°C). The differentially expressed mRNA between the stressed states (sampled just before the onset of bleaching) and the non stressed states (control) were isolated by Suppression Subtractive Hybridization. Transcription rates of the most interesting genes (considering their putative function) were quantified by Q-RT-PCR, which revealed a significant decrease in transcription of two candidates six days before bleaching. RACE-PCR experiments showed that one of them (PdC-Lectin) contained a C-Type-Lectin domain specific for mannose. Immunolocalisation demonstrated that this host gene mediates molecular interactions between the host and the symbionts suggesting a putative role in zooxanthellae acquisition and/or sequestration. The second gene corresponds to a gene putatively involved in calcification processes (Pdcyst-rich). Its down-regulation could reflect a trade-off mechanism leading to the arrest of the mineralization process under stress. Conclusion Under thermal

  3. The 2014 coral bleaching and freshwater flood events in Kāneʻohe Bay, Hawaiʻi

    PubMed Central

    Jokiel, Paul L.; Rodgers, Kuʻulei S.

    2015-01-01

    Until recently, subtropical Hawaiʻi escaped the major bleaching events that have devastated many tropical regions, but the continued increases in global long-term mean temperatures and the apparent ending of the Pacific Decadal Oscillation (PDO) cool phase have increased the risk of bleaching events. Climate models and observations predict that bleaching in Hawaiʻi will occur with increasing frequency and increasing severity over future decades. A freshwater “kill” event occurred during July 2014 in the northern part of Kāneʻohe Bay that reduced coral cover by 22.5% in the area directly impacted by flooding. A subsequent major bleaching event during September 2014 caused extensive coral bleaching and mortality throughout the bay and further reduced coral cover in the freshwater kill area by 60.0%. The high temperature bleaching event only caused a 1.0% reduction in live coral throughout the portion of the bay not directly impacted by the freshwater event. Thus, the combined impact of the low salinity event and the thermal bleaching event appears to be more than simply additive. The temperature regime during the September 2014 bleaching event was analogous in duration and intensity to that of the large bleaching event that occurred previously during August 1996, but resulted in a much larger area of bleaching and coral mortality. Apparently seasonal timing as well as duration and magnitude of heating is important. Coral spawning in the dominant coral species occurs early in the summer, so reservoirs of stored lipid in the corals had been depleted by spawning prior to the September 2014 event. Warm months above 27 °C result in lower coral growth and presumably could further decrease lipid reserves, leading to a bleaching event that was more severe than would have happened if the high temperatures occurred earlier in the summer. Hawaiian reef corals decrease skeletal growth at temperatures above 27 °C, so perhaps the “stress period” actually started long

  4. Remote sensing of sea surface temperatures during 2002 Barrier Reef coral bleaching

    NASA Astrophysics Data System (ADS)

    Liu, Gang; Strong, Alan E.; Skirving, William

    Early in 2002, satellites of the U.S. National Oceanic and Atmospheric Administration (NOAA) detected anomalously high sea surface temperatures (SST) developing in the western Coral Sea, midway along Australia's Great Barrier Reef (GBR). This was the beginning of what was to become the most significant GBR coral bleaching event on record [Wilkinson, 2002]. During this time, NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) provided satellite data as part of ongoing collaborative work on coral reef health with the Australian Institute of Marine Science (AIMS) and the Great Barrier Reef Marine Park Authority (GBRMPA). These data proved invaluable to AIMS and GBRMPA as they monitored and assessed the development and evolution of SSTs throughout the austral summer, enabling them to keep stakeholders, government, and the general public informed and up to date.

  5. Modulation of light-enhancement to symbiotic algae by light-scattering in corals and evolutionary trends in bleaching.

    PubMed

    Marcelino, Luisa A; Westneat, Mark W; Stoyneva, Valentina; Henss, Jillian; Rogers, Jeremy D; Radosevich, Andrew; Turzhitsky, Vladimir; Siple, Margaret; Fang, Andrew; Swain, Timothy D; Fung, Jennifer; Backman, Vadim

    2013-01-01

    Calcium carbonate skeletons of scleractinian corals amplify light availability to their algal symbionts by diffuse scattering, optimizing photosynthetic energy acquisition. However, the mechanism of scattering and its role in coral evolution and dissolution of algal symbioses during "bleaching" events are largely unknown. Here we show that differences in skeletal fractal architecture at nano/micro-lengthscales within 96 coral taxa result in an 8-fold variation in light-scattering and considerably alter the algal light environment. We identified a continuum of properties that fall between two extremes: (1) corals with low skeletal fractality that are efficient at transporting and redistributing light throughout the colony with low scatter but are at higher risk of bleaching and (2) corals with high skeletal fractality that are inefficient at transporting and redistributing light with high scatter and are at lower risk of bleaching. While levels of excess light derived from the coral skeleton is similar in both groups, the low-scatter corals have a higher rate of light-amplification increase when symbiont concentration is reduced during bleaching, thus creating a positive feedback-loop between symbiont concentration and light-amplification that exposes the remaining symbionts to increasingly higher light intensities. By placing our findings in an evolutionary framework, in conjunction with a novel empirical index of coral bleaching susceptibility, we find significant correlations between bleaching susceptibility and light-scattering despite rich homoplasy in both characters; suggesting that the cost of enhancing light-amplification to the algae is revealed in decreased resilience of the partnership to stress.

  6. Disease outbreaks, bleaching and a cyclone drive changes in coral assemblages on an inshore reef of the Great Barrier Reef

    NASA Astrophysics Data System (ADS)

    Haapkylä, J.; Melbourne-Thomas, J.; Flavell, M.; Willis, B. L.

    2013-09-01

    Coral disease is a major threat to the resilience of coral reefs; thus, understanding linkages between disease outbreaks and disturbances predicted to increase with climate change is becoming increasingly important. Coral disease surveys conducted twice yearly between 2008 and 2011 at a turbid inshore reef in the central Great Barrier Reef spanned two disturbance events, a coral bleaching event in 2009 and a severe cyclone (cyclone `Yasi') in 2011. Surveys of coral cover, community structure and disease prevalence throughout this 4-yr study provide a unique opportunity to explore cumulative impacts of disturbance events and disease for inshore coral assemblages. The principal coral disease at the study site was atramentous necrosis (AtN), and it primarily affected the key inshore, reef-building coral Montipora aequituberculata. Other diseases detected were growth anomalies, white syndrome and brown band syndrome. Diseases affected eight coral genera, although Montipora was, by far, the genus mostly affected. The prevalence of AtN followed a clear seasonal pattern, with disease outbreaks occurring only in wet seasons. Mean prevalence of AtN on Montipora spp. (63.8 % ± 3.03) was three- to tenfold greater in the wet season of 2009, which coincided with the 2009 bleaching event, than in other years. Persistent wet season outbreaks of AtN combined with the impacts of bleaching and cyclone events resulted in a 50-80 % proportional decline in total coral cover. The greatest losses of branching and tabular acroporids occurred following the low-salinity-induced bleaching event of 2009, and the greatest losses of laminar montiporids occurred following AtN outbreaks in 2009 and in 2011 following cyclone Yasi. The shift to a less diverse coral assemblage and the concomitant loss of structural complexity are likely to have long-term consequences for associated vertebrate and invertebrate communities on Magnetic Island reefs.

  7. Water quality and coral bleaching thresholds: formalising the linkage for the inshore reefs of the Great Barrier Reef, Australia.

    PubMed

    Wooldridge, Scott A

    2009-05-01

    The threats of wide-scale coral bleaching and reef demise associated with anthropogenic climate change are widely known. Here, the additional role of poor water quality in lowering the thermal tolerance (i.e. bleaching 'resistance') of symbiotic reef corals is considered. In particular, a quantitative linkage is established between terrestrially-sourced dissolved inorganic nitrogen (DIN) loading and the upper thermal bleaching thresholds of inshore reefs on the Great Barrier Reef, Australia. Significantly, this biophysical linkage provides concrete evidence for the oft-expressed belief that improved coral reef management will increase the regional-scale survival prospects of corals reefs to global climate change. Indeed, for inshore reef areas with a high runoff exposure risk, it is shown that the potential benefit of this 'local' management imperative is equivalent to approximately 2.0-2.5 degrees C in relation to the upper thermal bleaching limit; though in this case, a potentially cost-prohibitive reduction in end-of-river DIN of >50-80% would be required. An integrated socio-economic modelling framework is outlined that will assist future efforts to understand (optimise) the alternate tradeoffs that the water quality/coral bleaching linkage presents.

  8. Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates.

    PubMed

    Rosset, Sabrina; Wiedenmann, Jörg; Reed, Adam J; D'Angelo, Cecilia

    2017-02-24

    Enrichment of reef environments with dissolved inorganic nutrients is considered a major threat to the survival of corals living in symbiosis with dinoflagellates (Symbiodinium sp.). We argue, however, that the direct negative effects on the symbiosis are not necessarily caused by the nutrient enrichment itself but by the phosphorus starvation of the algal symbionts that can be caused by skewed nitrogen (N) to phosphorus (P) ratios. We exposed corals to imbalanced N:P ratios in long-term experiments and found that the undersupply of phosphate severely disturbed the symbiosis, indicated by the loss of coral biomass, malfunctioning of algal photosynthesis and bleaching of the corals. In contrast, the corals tolerated an undersupply with nitrogen at high phosphate concentrations without negative effects on symbiont photosynthesis, suggesting a better adaptation to nitrogen limitation. Transmission electron microscopy analysis revealed that the signatures of ultrastructural biomarkers represent versatile tools for the classification of nutrient stress in symbiotic algae. Notably, high N:P ratios in the water were clearly identified by the accumulation of uric acid crystals.

  9. Modulation of Light-Enhancement to Symbiotic Algae by Light-Scattering in Corals and Evolutionary Trends in Bleaching

    PubMed Central

    Marcelino, Luisa A.; Westneat, Mark W.; Stoyneva, Valentina; Henss, Jillian; Rogers, Jeremy D.; Radosevich, Andrew; Turzhitsky, Vladimir; Siple, Margaret; Fang, Andrew; Swain, Timothy D.; Fung, Jennifer; Backman, Vadim

    2013-01-01

    Calcium carbonate skeletons of scleractinian corals amplify light availability to their algal symbionts by diffuse scattering, optimizing photosynthetic energy acquisition. However, the mechanism of scattering and its role in coral evolution and dissolution of algal symbioses during “bleaching” events are largely unknown. Here we show that differences in skeletal fractal architecture at nano/micro-lengthscales within 96 coral taxa result in an 8-fold variation in light-scattering and considerably alter the algal light environment. We identified a continuum of properties that fall between two extremes: (1) corals with low skeletal fractality that are efficient at transporting and redistributing light throughout the colony with low scatter but are at higher risk of bleaching and (2) corals with high skeletal fractality that are inefficient at transporting and redistributing light with high scatter and are at lower risk of bleaching. While levels of excess light derived from the coral skeleton is similar in both groups, the low-scatter corals have a higher rate of light-amplification increase when symbiont concentration is reduced during bleaching, thus creating a positive feedback-loop between symbiont concentration and light-amplification that exposes the remaining symbionts to increasingly higher light intensities. By placing our findings in an evolutionary framework, in conjunction with a novel empirical index of coral bleaching susceptibility, we find significant correlations between bleaching susceptibility and light-scattering despite rich homoplasy in both characters; suggesting that the cost of enhancing light-amplification to the algae is revealed in decreased resilience of the partnership to stress. PMID:23630594

  10. Species-specific control of external superoxide levels by the coral holobiont during a natural bleaching event

    NASA Astrophysics Data System (ADS)

    Diaz, Julia M.; Hansel, Colleen M.; Apprill, Amy; Brighi, Caterina; Zhang, Tong; Weber, Laura; McNally, Sean; Xun, Liping

    2016-12-01

    The reactive oxygen species superoxide (O2.-) is both beneficial and detrimental to life. Within corals, superoxide may contribute to pathogen resistance but also bleaching, the loss of essential algal symbionts. Yet, the role of superoxide in coral health and physiology is not completely understood owing to a lack of direct in situ observations. By conducting field measurements of superoxide produced by corals during a bleaching event, we show substantial species-specific variation in external superoxide levels, which reflect the balance of production and degradation processes. Extracellular superoxide concentrations are independent of light, algal symbiont abundance and bleaching status, but depend on coral species and bacterial community composition. Furthermore, coral-derived superoxide concentrations ranged from levels below bulk seawater up to ~120 nM, some of the highest superoxide concentrations observed in marine systems. Overall, these results unveil the ability of corals and/or their microbiomes to regulate superoxide in their immediate surroundings, which suggests species-specific roles of superoxide in coral health and physiology.

  11. Species-specific control of external superoxide levels by the coral holobiont during a natural bleaching event

    PubMed Central

    Diaz, Julia M.; Hansel, Colleen M.; Apprill, Amy; Brighi, Caterina; Zhang, Tong; Weber, Laura; McNally, Sean; Xun, Liping

    2016-01-01

    The reactive oxygen species superoxide (O2·−) is both beneficial and detrimental to life. Within corals, superoxide may contribute to pathogen resistance but also bleaching, the loss of essential algal symbionts. Yet, the role of superoxide in coral health and physiology is not completely understood owing to a lack of direct in situ observations. By conducting field measurements of superoxide produced by corals during a bleaching event, we show substantial species-specific variation in external superoxide levels, which reflect the balance of production and degradation processes. Extracellular superoxide concentrations are independent of light, algal symbiont abundance and bleaching status, but depend on coral species and bacterial community composition. Furthermore, coral-derived superoxide concentrations ranged from levels below bulk seawater up to ∼120 nM, some of the highest superoxide concentrations observed in marine systems. Overall, these results unveil the ability of corals and/or their microbiomes to regulate superoxide in their immediate surroundings, which suggests species-specific roles of superoxide in coral health and physiology. PMID:27924868

  12. Light-induced dissociation of antenna complexes in the symbionts of scleractinian corals correlates with sensitivity to coral bleaching

    NASA Astrophysics Data System (ADS)

    Hill, R.; Larkum, A. W. D.; Prášil, O.; Kramer, D. M.; Szabó, M.; Kumar, V.; Ralph, P. J.

    2012-12-01

    Elevated temperatures in combination with moderate to high irradiance are known to cause bleaching events in scleractinian corals, characterised by damage to photosystem II (PSII). Photoprotective mechanisms of the symbiont can reduce the excitation pressure impinging upon PSII. In the bleaching sensitive species, Acropora millepora and Pocillopora damicornis, high light alone induced photoprotection through the xanthophyll cycle, increased content of the antioxidant carotenoid, β-carotene, as well as the dissociation of the light-harvesting chlorophyll complexes. The evidence is compatible with either the membrane-bound chlorophyll a-chlorophyll c 2-peridinin-protein (acpPC) complex or the peripheral peridinin-chlorophyll-protein complex, or both, disconnecting from PSII under high light. The acpPC complex potentially showed a state transition response with redistribution towards photosystem I to reduce PSII over-excitation. This apparent acpPC dissociation/reassociation was promoted by the addition of the xanthophyll cycle inhibitor, dithiothreitol, under high irradiance. Exposure to thermal stress as well as high light promoted xanthophyll de-epoxidation and increased β-carotene content, although it did not influence light-harvesting chlorophyll complex (LHC) dissociation, indicating light, rather than temperature, controls LHC dissociation. Photoinhibition was avoided in the bleaching tolerant species, Pavona decussata, suggesting xanthophyll cycling along with LHC dissociation may have been sufficient to prevent photodamage to PSII. Symbionts of P. decussata also displayed the greatest detachment of antenna complexes, while the more thermally sensitive species, Pocillopora damicornis and A. millepora, showed less LHC dissociation, suggesting antenna movement influences bleaching susceptibility.

  13. The reef coral Goniastrea aspera: a `winner' becomes a `loser' during a severe bleaching event in Thailand

    NASA Astrophysics Data System (ADS)

    Brown, B. E.; Dunne, R. P.; Phongsuwan, N.; Patchim, L.; Hawkridge, J. M.

    2014-06-01

    The reef coral Goniastrea aspera is regarded as one of the most environmentally tolerant species on Indo-Pacific reefs. Its demise, following a severe bleaching event in the Andaman Sea in the north-eastern Indian Ocean in 2010, was surprising in view of the rapid recovery of co-existing species such as Porites lutea. Demographic studies of G. aspera at this site showed the population was mainly composed of large individuals, which recruited in the early 1990s. These results, and size-specific mortality observed in G. aspera, post-bleaching, suggest that factors, related to size and age, may have contributed to the coral's marked decline.

  14. Species-specific trends in the reproductive output of corals across environmental gradients and bleaching histories.

    PubMed

    Howells, Emily J; Ketchum, Remi N; Bauman, Andrew G; Mustafa, Yasmine; Watkins, Kristina D; Burt, John A

    2016-04-30

    Coral populations in the Persian Gulf have a reputation for being some of the toughest in the world yet little is known about the energetic constraints of living under temperature and salinity extremes. Energy allocation for sexual reproduction in Gulf corals was evaluated relative to conspecifics living under milder environmental conditions in the Oman Sea. Fecundity was depressed at Gulf sites in two Indo-Pacific merulinid species (Cyphastrea microphthalma and Platygyra daedalea) but not in a regionally endemic acroporid (Acropora downingi). Gulf populations of each species experienced high temperature bleaching at the onset of gametogenesis in the study but fecundity was only negatively impacted in P. daedalea and A. downingi. Large population sizes of C. microphthalma and P. daedalea in the Gulf are expected to buffer reductions on colony-level fecundity. However, depleted population sizes of A. downingi at some Gulf sites equate to low reef-wide fecundity and likely impede outcrossing success.

  15. Changes in the fluorescence of the Caribbean coral Montastraea faveolata during heat-induced bleaching

    USGS Publications Warehouse

    Zawada, David G.; Jaffe, J.S.

    2003-01-01

    In order to evaluate the response of commonly occurring green and orange fluorescent host-based pigments, a thermal stress experiment was performed on specimens of the Caribbean coral Montastraea faveolata. Seven paired samples were collected from a small oceanic reef near Lee Stocking Island in the Bahamas. Seven of the fourteen corals were subjected to elevated temperatures for 28 d, followed by a recovery period lasting 53 d. Throughout the experiment, high-resolution (~400 µm pixel-1) multispectral images of induced fluorescence were recorded at wavelengths corresponding to the green and orange host pigments, plus chlorophyll. These images revealed that the fluorescence of both host pigments was concentrated at polyp centers and declined by 70–90% in regions between polyps. Chlorophyll fluorescence, however, was distributed almost uniformly across the entire coral surface, but with decreases of 10–30% around polyp centers. A normalized difference ratio between the green and orange pigments (GO ratio) was developed to facilitate comparison with chlorophyll fluorescence as a bleaching indicator. Analysis showed a high correspondence between a sustained GO ratio of less than zero and the death of corals. Finally, this ratio was resistant to contamination from other sources of chlorophyll fluorescence, such as filamentous algae.

  16. A community change in the algal endosymbionts of a scleractinian coral following a natural bleaching event: field evidence of acclimatization.

    PubMed

    Jones, A M; Berkelmans, R; van Oppen, M J H; Mieog, J C; Sinclair, W

    2008-06-22

    The symbiosis between reef-building corals and their algal endosymbionts (zooxanthellae of the genus Symbiodinium) is highly sensitive to temperature stress, which makes coral reefs vulnerable to climate change. Thermal tolerance in corals is known to be substantially linked to the type of zooxanthellae they harbour and, when multiple types are present, the relative abundance of types can be experimentally manipulated to increase the thermal limits of individual corals. Although the potential exists for this to translate into substantial thermal acclimatization of coral communities, to date there is no evidence to show that this takes place under natural conditions. In this study, we show field evidence of a dramatic change in the symbiont community of Acropora millepora, a common and widespread Indo-Pacific hard coral species, after a natural bleaching event in early 2006 in the Keppel Islands (Great Barrier Reef). Before bleaching, 93.5% (n=460) of the randomly sampled and tagged colonies predominantly harboured the thermally sensitive Symbiodinium type C2, while the remainder harboured a tolerant Symbiodinium type belonging to clade D or mixtures of C2 and D. After bleaching, 71% of the surviving tagged colonies that were initially C2 predominant changed to D or C1 predominance. Colonies that were originally C2 predominant suffered high mortality (37%) compared with D-predominant colonies (8%). We estimate that just over 18% of the original A. millepora population survived unchanged leaving 29% of the population C2 and 71% D or C1 predominant six months after the bleaching event. This change in the symbiont community structure, while it persists, is likely to have substantially increased the thermal tolerance of this coral population. Understanding the processes that underpin the temporal changes in symbiont communities is key to assessing the acclimatization potential of reef corals.

  17. 2005 Caribbean mass coral bleaching event: A sea surface temperature empirical orthogonal teleconnection analysis

    NASA Astrophysics Data System (ADS)

    Simonti, Alicia L.; Eastman, J. Ronald

    2010-11-01

    This study examined the effects of climate teleconnections on the massive Caribbean coral bleaching and mortality event of 2005. A relatively new analytical procedure known as empirical orthogonal teleconnection (EOT) analysis, based on a 26 year monthly time series of observed sea surface temperature (SST), was employed. Multiple regression analysis was then utilized to determine the relative teleconnection contributions to SST variability in the southern Caribbean. The results indicate that three independent climate teleconnections had significant impact on southern Caribbean anomalies in SST and that their interaction was a major contributor to the anomalously high temperatures in 2005. The primary and approximately equal contributors were EOT-5 and EOT-2, which correlate most strongly with the tropical North Atlantic (TNA) and Atlantic multidecadal oscillation (AMO) climate indices, respectively. The third, EOT-9, was most strongly related to the Atlantic meridional mode. However, although statistically significant, the magnitude of its contribution to southern Caribbean variability was small. While there is debate over the degree to which the recent AMO pattern represents natural variability or global ocean warming, the results presented here indicate that natural variability played a strong role in the 2005 coral bleaching conditions. They also argue for a redefinition of the geography of TNA variability.

  18. Warming Trends and Bleaching Stress of the World’s Coral Reefs 1985–2012

    PubMed Central

    Heron, Scott F.; Maynard, Jeffrey A.; van Hooidonk, Ruben; Eakin, C. Mark

    2016-01-01

    Coral reefs across the world’s oceans are in the midst of the longest bleaching event on record (from 2014 to at least 2016). As many of the world’s reefs are remote, there is limited information on how past thermal conditions have influenced reef composition and current stress responses. Using satellite temperature data for 1985–2012, the analysis we present is the first to quantify, for global reef locations, spatial variations in warming trends, thermal stress events and temperature variability at reef-scale (~4 km). Among over 60,000 reef pixels globally, 97% show positive SST trends during the study period with 60% warming significantly. Annual trends exceeded summertime trends at most locations. This indicates that the period of summer-like temperatures has become longer through the record, with a corresponding shortening of the ‘winter’ reprieve from warm temperatures. The frequency of bleaching-level thermal stress increased three-fold between 1985–91 and 2006–12 – a trend climate model projections suggest will continue. The thermal history data products developed enable needed studies relating thermal history to bleaching resistance and community composition. Such analyses can help identify reefs more resilient to thermal stress. PMID:27922080

  19. Warming Trends and Bleaching Stress of the World's Coral Reefs 1985-2012.

    PubMed

    Heron, Scott F; Maynard, Jeffrey A; van Hooidonk, Ruben; Eakin, C Mark

    2016-12-06

    Coral reefs across the world's oceans are in the midst of the longest bleaching event on record (from 2014 to at least 2016). As many of the world's reefs are remote, there is limited information on how past thermal conditions have influenced reef composition and current stress responses. Using satellite temperature data for 1985-2012, the analysis we present is the first to quantify, for global reef locations, spatial variations in warming trends, thermal stress events and temperature variability at reef-scale (~4 km). Among over 60,000 reef pixels globally, 97% show positive SST trends during the study period with 60% warming significantly. Annual trends exceeded summertime trends at most locations. This indicates that the period of summer-like temperatures has become longer through the record, with a corresponding shortening of the 'winter' reprieve from warm temperatures. The frequency of bleaching-level thermal stress increased three-fold between 1985-91 and 2006-12 - a trend climate model projections suggest will continue. The thermal history data products developed enable needed studies relating thermal history to bleaching resistance and community composition. Such analyses can help identify reefs more resilient to thermal stress.

  20. Warming Trends and Bleaching Stress of the World’s Coral Reefs 1985–2012

    NASA Astrophysics Data System (ADS)

    Heron, Scott F.; Maynard, Jeffrey A.; van Hooidonk, Ruben; Eakin, C. Mark

    2016-12-01

    Coral reefs across the world’s oceans are in the midst of the longest bleaching event on record (from 2014 to at least 2016). As many of the world’s reefs are remote, there is limited information on how past thermal conditions have influenced reef composition and current stress responses. Using satellite temperature data for 1985–2012, the analysis we present is the first to quantify, for global reef locations, spatial variations in warming trends, thermal stress events and temperature variability at reef-scale (~4 km). Among over 60,000 reef pixels globally, 97% show positive SST trends during the study period with 60% warming significantly. Annual trends exceeded summertime trends at most locations. This indicates that the period of summer-like temperatures has become longer through the record, with a corresponding shortening of the ‘winter’ reprieve from warm temperatures. The frequency of bleaching-level thermal stress increased three-fold between 1985–91 and 2006–12 – a trend climate model projections suggest will continue. The thermal history data products developed enable needed studies relating thermal history to bleaching resistance and community composition. Such analyses can help identify reefs more resilient to thermal stress.

  1. Downscaled projections of Caribbean coral bleaching that can inform conservation planning.

    PubMed

    van Hooidonk, Ruben; Maynard, Jeffrey Allen; Liu, Yanyun; Lee, Sang-Ki

    2015-09-01

    Projections of climate change impacts on coral reefs produced at the coarse resolution (~1°) of Global Climate Models (GCMs) have informed debate but have not helped target local management actions. Here, projections of the onset of annual coral bleaching conditions in the Caribbean under Representative Concentration Pathway (RCP) 8.5 are produced using an ensemble of 33 Coupled Model Intercomparison Project phase-5 models and via dynamical and statistical downscaling. A high-resolution (~11 km) regional ocean model (MOM4.1) is used for the dynamical downscaling. For statistical downscaling, sea surface temperature (SST) means and annual cycles in all the GCMs are replaced with observed data from the ~4-km NOAA Pathfinder SST dataset. Spatial patterns in all three projections are broadly similar; the average year for the onset of annual severe bleaching is 2040-2043 for all projections. However, downscaled projections show many locations where the onset of annual severe bleaching (ASB) varies 10 or more years within a single GCM grid cell. Managers in locations where this applies (e.g., Florida, Turks and Caicos, Puerto Rico, and the Dominican Republic, among others) can identify locations that represent relative albeit temporary refugia. Both downscaled projections are different for the Bahamas compared to the GCM projections. The dynamically downscaled projections suggest an earlier onset of ASB linked to projected changes in regional currents, a feature not resolved in GCMs. This result demonstrates the value of dynamical downscaling for this application and means statistically downscaled projections have to be interpreted with caution. However, aside from west of Andros Island, the projections for the two types of downscaling are mostly aligned; projected onset of ASB is within ±10 years for 72% of the reef locations.

  2. Abundance, composition and growth rate of coral recruits on dead corals following the 2010 bleaching event at Mu Ko Surin, the Andaman Sea

    NASA Astrophysics Data System (ADS)

    Yucharoen, Mathinee; Yeemin, Thamasak; Casareto, Beatriz E.; Suzuki, Yoshimi; Samsuvan, Watchara; Sangmanee, Kanwara; Klinthong, Wanlaya; Pengsakun, Sittiporn; Sutthacheep, Makamas

    2015-06-01

    Elevated seawater temperatures in the summer months of 2010 were associated with widespread coral mortality in Thailand. A large number of corals at Mu Ko Surin died following the bleaching event. Understanding of the recruitment of corals would improve our ability to predict the potential for coral recovery from the impacts of bleaching events, as well as the interpretation of spatio-temporal variability in coral community structure. This study aims to examine the composition, abundance and growth rate of juvenile corals and the potential of reef recovery at Mu Ko Surin in order to help to understand how reefs react to major disturbances. We found that the densities of coral recruits varied among years and study sites. In the year 2011, coral recruitments ranged between 0.18 ± 0.02 to 1.67 ± 0.07 recruits per m2 for 10 study sites. While in 2012, the monitoring revealed a range between 0.96 ± 0.16 and 2.19 ± 0.21 recruits per m2 from 5 study sites. Fungia, Acropora, Porites and Favites were the dominant groups of coral recruits. In terms substrate forms, they were significant differences between sampling years but the preferential dominant substrate forms did not differ. The Acropora recruits at Ko Torinla showed normal distributions of size class during the two periods. Their ranges in 2011 and 2012 were 4-30 and 13-54 mm, respectively. Six species of Acropora recruits, i.e. Acropora intermedia, A. nasuta, A. cerealis, A. subulata, A. muricata and A. latistella were found. They showed diverse growth rates due to the spatial distribution of 2.11 ± 0.59 to 7.47 ± 1.37 cm per year. This study provides useful data in terms of coral recruitment and recovery from degradation and disturbance, especially from temperature changes induced by coral bleaching. The findings suggest that there is the possibility for coral recovery around Mu Ko Surin following the 2010 bleaching event.

  3. Kinetic and metabolic isotope effects in coral skeletal carbon isotopes: A re-evaluation using experimental coral bleaching as a case study

    NASA Astrophysics Data System (ADS)

    Schoepf, Verena; Levas, Stephen J.; Rodrigues, Lisa J.; McBride, Michael O.; Aschaffenburg, Matthew D.; Matsui, Yohei; Warner, Mark E.; Hughes, Adam D.; Grottoli, Andréa G.

    2014-12-01

    Coral skeletal δ13C can be a paleo-climate proxy for light levels (i.e., cloud cover and seasonality) and for photosynthesis to respiration (P/R) ratios. The usefulness of coral δ13C as a proxy depends on metabolic isotope effects (related to changes in photosynthesis) being the dominant influence on skeletal δ13C. However, it is also influenced by kinetic isotope effects (related to calcification rate) which can overpower metabolic isotope effects and thus compromise the use of coral skeletal δ13C as a proxy. Heikoop et al. (2000) proposed a simple data correction to remove kinetic isotope effects from coral skeletal δ13C, as well as an equation to calculate P/R ratios from coral isotopes. However, despite having been used by other researchers, the data correction has never been directly tested, and isotope-based P/R ratios have never been compared to P/R ratios measured using respirometry. Experimental coral bleaching represents a unique environmental scenario to test this because bleaching produces large physiological responses that influence both metabolic and kinetic isotope effects in corals. Here, we tested the δ13C correction and the P/R calculation using three Pacific and three Caribbean coral species from controlled temperature-induced bleaching experiments where both the stable isotopes and the physiological variables that cause isotopic fractionation (i.e., photosynthesis, respiration, and calcification) were simultaneously measured. We show for the first time that the data correction proposed by Heikoop et al. (2000) does not effectively remove kinetic effects in the coral species studied here, and did not improve the metabolic signal of bleached and non-bleached corals. In addition, isotope-based P/R ratios were in poor agreement with measured P/R ratios, even when the data correction was applied. This suggests that additional factors influence δ13C and δ18O, which are not accounted for by the data correction. We therefore recommend that the

  4. Identity and diversity of coral endosymbionts (zooxanthellae) from three Palauan reefs with contrasting bleaching, temperature and shading histories.

    PubMed

    Fabricius, K E; Mieog, J C; Colin, P L; Idip, D; van Oppen, M J H

    2004-08-01

    The potential of corals to associate with more temperature-tolerant strains of algae (zooxanthellae, Symbiodinium) can have important implications for the future of coral reefs in an era of global climate change. In this study, the genetic identity and diversity of zooxanthellae was investigated at three reefs with contrasting histories of bleaching mortality, water temperature and shading, in the Republic of Palau (Micronesia). Single-stranded conformation polymorphism and sequence analysis of the ribosomal DNA internal transcribed spacer (ITS)1 region was used for genotyping. A chronically warm but partly shaded coral reef in a marine lake that is hydrographically well connected to the surrounding waters harboured only two single-stranded conformation polymorphism profiles (i.e. zooxanthella communities). It consisted only of Symbiodinium D in all 13 nonporitid species and two Porites species investigated, with the remaining five Porites harbouring C*. Despite the high temperature in this lake (> 0.5 degrees above ambient), this reef did not suffer coral mortality during the (1998) bleaching event, however, no bleaching-sensitive coral families and genera occur in the coral community. This setting contrasts strongly with two other reefs with generally lower temperatures, in which 10 and 12 zooxanthella communities with moderate to low proportions of clade D zooxanthellae were found. The data indicate that whole coral assemblages, when growing in elevated seawater temperatures and at reduced irradiance, can be composed of colonies associated with the more thermo-tolerant clade D zooxanthellae. Future increases in seawater temperature might, therefore, result in an increasing prevalence of Symbiodinium phylotype D in scleractinian corals, possibly associated with a loss of diversity in both zooxanthellae and corals.

  5. Comparing bleaching and mortality responses of hard corals between southern Kenya and the Great Barrier Reef, Australia.

    PubMed

    McClanahan, T R; Baird, A H; Marshall, P A; Toscano, M A

    2004-02-01

    We compared the bleaching and mortality response (BMI) of 19 common scleractinian corals to an anomalous warm-water event in 1998 to determine the degree of variation between depths, sites, and regions. Mombasa corals experienced a greater temperature anomaly than those on the Great Barrier Reef (GBR) sites and this was reflected in the greater BMI response of most taxa. Comparing coral taxa in different sites at the same depth produced high correlation coefficients in the bleaching response in Kenya at 2 m (r=0.86) and GBR at 6 m depth sites (r=0.80) but less in the GBR for shallow 2 m sites (r=0.49). The pattern of taxa susceptibility was remarkably consistent between the regions. Coral taxa explained 52% of the variation in the response of colonies to bleaching between these two regions (Kenya BMI=0.90 GBR BMI+26; F(1,19) - 18.3; p < 0.001; r2 = 0.52). Stylophora and Pocillopora were consistently susceptible while Cyphastrea, Goniopora Galaxea and Pavona were resistant in both regions. Three taxa behaved differently between the two regions; Acropora, and branching Porites were both moderately affected on the GBR but were highly affected in Kenya while the opposite was true for Pavona. These results suggest that a colonies response to bleaching is phylogenetically constrained, emphasizing the importance of features of the host's physiology or morphology in determining the response to thermal stress.

  6. Equivocal evidence for a thermostat and unusually low levels of coral bleaching in the Western Pacific Warm Pool

    NASA Astrophysics Data System (ADS)

    van Hooidonk, Ruben; Huber, Matthew

    2009-03-01

    An ocean ``thermostat'' was recently proposed that limits Western Pacific Warm Pool (WPWP) sea surface temperature (SST) causing anomalously low coral bleaching rates. We analyze WPWP SST trends and bleaching using HadISST data and a coral bleaching database and find no strong evidence for a thermostat or for anomalously low bleaching. A region within the WPWP has a trend of maximum SST near zero, but this signal is not robust - by using different data or periods the signal disappears. We do find a negative correlation between the average warmest month for the years 1950-1969 (average SST max) and the linear trend of maximum monthly temperatures for the years 1950-2006 (linear trend SST max). However this correlation is not unique to the WPWP, it is also observed in a cooler region. Consequently it can not be explained by a thermostat. The observed sparsity of bleaching observations in the WPWP is not in agreement with estimated bleaching likelihood. The sparsity of observations is more likely due to the WPWP's remoteness.

  7. ReefTemp: An interactive monitoring system for coral bleaching using high-resolution SST and improved stress predictors

    NASA Astrophysics Data System (ADS)

    Maynard, Jeffrey A.; Turner, Peter J.; Anthony, Kenneth R. N.; Baird, Andrew H.; Berkelmans, Ray; Eakin, C. Mark; Johnson, Johanna; Marshall, Paul A.; Packer, Gareck R.; Rea, Anthony; Willis, Bette L.

    2008-03-01

    Anomalously high sea surface temperatures (SST) have led to repeated mass coral bleaching events on a global scale. Existing satellite-based systems used to monitor conditions conducive to bleaching are based on low-resolution (0.5°, ~50 km) SST data. While these systems have served the research and management community well, they have inherent weaknesses that limit their capacity to predict stress on coral reefs at local scales, over which bleaching severity is known to vary dramatically. Here we discuss the development and testing of ReefTemp, a new operational remote sensing application for the Great Barrier Reef that assesses bleaching risk daily using: high-resolution (2 km) SST, regionally validated thermal stress indices, and color-graded legends directly related to past observations of bleaching severity. Given projections of sea temperature rise, ReefTemp is timely as it can accurately predict bleaching severity at a local scale and therefore help to give focus to future research and monitoring efforts.

  8. Multiple scales of genetic connectivity in a brooding coral on isolated reefs following catastrophic bleaching.

    PubMed

    Underwood, J N; Smith, L D; Van Oppen, M J H; Gilmour, J P

    2007-02-01

    Understanding the pattern of connectivity among populations is crucial for the development of realistic and spatially explicit population models in marine systems. Here we analysed variation at eight microsatellite loci to assess the genetic structure and to infer patterns of larval dispersal for a brooding coral, Seriatopora hystrix, at an isolated system of reefs in northern Western Australia. Spatial autocorrelation analyses show that populations are locally subdivided, and that the majority of larvae recruit to within 100 m of their natal colony. Further, a combination of F- and R- statistics showed significant differentiation at larger spatial scales (2-60 km) between sites, and this pattern was clearly not associated with distance. However, Bayesian analysis demonstrated that recruitment has been supplemented by less frequent but recent input of larvae from outside the local area; 2-6% of colonies were excluded from the site at which they were sampled. Individual assignments of these migrants to the most likely populations suggest that the majority of migrants were produced at the only site that was not decimated by a recent and catastrophic coral bleaching event. Furthermore, the only site that recovered to prebleaching levels received most of these immigrants. We conclude that the genetic structure of this brooding coral reflects its highly opportunistic life history, in which prolific, philopatric recruitment is occasionally supplemented by exogenously produced larvae.

  9. Detecting coral bleaching using high-resolution satellite data analysis and 2-dimensional thermal model simulation in the Ishigaki fringing reef, Japan

    NASA Astrophysics Data System (ADS)

    Dadhich, A. P.; Nadaoka, K.; Yamamoto, T.; Kayanne, H.

    2012-06-01

    In 2007, high-temperature-induced mass coral mortality was observed in a well-developed fringing reef area on the southeastern coast of Ishigaki Island, Japan. To analyze the response of the corals to thermal stress, the coral cover was examined using Quickbird data, taken across the reef flat just before and after the bleaching event and performing a reef scale horizontal 2-dimensional thermal model simulation. The Quickbird data consisted of multispectral (MSS) imagery, which had a spatial resolution of 2.4 m, and panchromatic (PAN)-fused multispectral imagery, which had a 0.6-m spatial resolution. The observed changes in coral cover implied that the delineation of partially bleached coral was more precise with PAN + MSS. The classification accuracy achieved using PAN + MSS (93%) was superior to that obtained using MSS (88%). The in situ water temperature observations and 2-dimensional thermal model simulation results indicated that the water temperature fluctuated greatly in the inner reef area in late July 2007. Different thermal stress indices, including daily average temperature, daily maximum excess temperature, and daily accumulated temperature, were examined to define a suitable index that represented the severity of the thermal stress on coral cover. The results suggested that the daily accumulated temperature that occurred during the maximum sea surface temperature period of the bleaching season provided the best predictor of bleaching. The changes in water temperature, bathymetry, and coral patch size affected the severity of bleaching; therefore, the spatial dependence of these variables was examined using Moran's I and Lagrange multiplier tests. An investigation of the effect of coral patch sizes on coral bleaching indicated that large coral patches were less affected than the small patches, which were more likely to suffer bleaching and coral mortality.

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

    PubMed

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

    2016-01-01

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

  11. Marine Cloud Brightening: regional applications to the weakening of hurricanes and reduction in coral bleaching

    NASA Astrophysics Data System (ADS)

    Gadian, A.; Hauser, R.; Kleypas, J. A.; Latham, J.; Parkes, B.; Salter, S.

    2013-12-01

    This study examines the potential to cool ocean surface waters in regions of hurricane genesis and early development. This would be achieved by seeding, with copious quantities of seawater cloud condensation nuclei (CCN), low-level maritime stratocumulus clouds covering these regions or those at the source of incoming currents. Higher cloud droplet density would increase these clouds' reflectivity to incoming sunlight, and possibly their longevity. This approach is a more localized application of the Marine Cloud Brightening (MCB) geoengineering technique promoting global cooling. By utilizing a climate ocean/atmosphere coupled model, HadGEM1, and by judicious seeding of maritime stratocumulus clouds, we demonstrate that we may be able to significantly reduce sea surface temperatures (SSTs) in hurricane development regions. Thus artificial seeding may reduce hurricane intensity; but how well the magnitude of this effect is yet to be determined. Increases in coral bleaching events over the last few decades have been largely caused by rising SSTs, and continued warming is expected to cause even greater increases through this century. Using thr same Global Climate Model to examine the potential of MCB to cool oceanic surface waters in three coral reef provinces. Our simulations indicate that under doubled CO2 conditions, the substantial increases in coral bleaching conditions from current values in three reef regions (Caribbean, French Polynesia, and the Great Barrier Reef) were eliminated when MCB was applied, which reduced the SSTs at these sites roughly to their original values. In this study we also illustrate how even regional application of MCB can affect the planetary meridional heat flux and the reduction in poleward heat transfer. (a) Change in annual average sea surface temperature, Celsius, between the 2xCO2 and CONTROL simulations. (b) Change in annual average sea surface temperature, Celsius, between the CONTROL and 2xCO2+MCB simulations. The dashed black

  12. Ten years of change to coral communities off Mona and Desecheo Islands, Puerto Rico, from disease and bleaching.

    PubMed

    Bruckner, Andrew W; Hill, Ronald L

    2009-11-16

    Remote reefs off southwest Puerto Rico have experienced recent losses in live coral cover of 30 to 80%, primarily due to the decline of Montastraea annularis and M. faveolata from disease and bleaching. These species were formerly the largest, oldest, and most abundant corals on these reefs, constituting over 65% of the living coral cover and 40 to 80% of the total number of colonies. From 1998 to 2001, outbreaks of yellow band disease (YBD) and white plague (WP) affected 30 to 60% of the M. annularis (complex) colonies. Disease prevalence declined beginning in 2002, and then increased immediately following the 2005 mass bleaching event. Colonies of M. annularis (complex) have been reduced in abundance by 24 to 32%, and remaining colonies are missing more than half their tissue. Both M. annularis and M. faveolata have failed to recruit, resheeting has been minimal, and exposed skeletal surfaces are being colonized by macroalgae, bioeroding sponges, and hydrozoans. Other scleractinian corals were smaller in size (mean = 28 cm diameter) and exhibited lower levels of partial mortality; these taxa were affected to a lesser extent by coral diseases and bleaching-associated tissue loss over the last decade. The numbers of small colonies (1 to 9 cm) of these species identified since 2005 also exceeded numbers of larger colonies that died. These reefs appear to be exhibiting shifts in species assemblages, with replacement of M. annularis (complex) by shorter-lived brooding species and other massive and plating corals (Agaricia, Porites, Meandrina, Eusmilia, Diploria, and Siderastrea spp.). To avoid a catastrophic and permanent loss of the dominant, slow-growing reef-building corals, the causes and effects of diseases need to be better understood, and possible control mechanisms must be developed. In particular, steps must be taken to mitigate environmental and anthropogenic stressors that increase the spread and severity of disease.

  13. Effect of colony size and surrounding substrate on corals experiencing a mild bleaching event on Heron Island reef flat (southern Great Barrier Reef, Australia)

    NASA Astrophysics Data System (ADS)

    Ortiz, J. C.; Gomez-Cabrera, M. Del C.; Hoegh-Guldberg, O.

    2009-12-01

    In January-May 2006, Heron Island in the Great Barrier Reef experienced a mild bleaching event. The effect of colony size, morphology and surrounding substrate on the extent of bleaching was explored. In contrast with previous studies, colony size did not influence bleaching sensitivity, suggesting that there may be a threshold of light and temperature stress beyond which size plays a role. Also contrasting with previous studies, massive corals were more affected by bleaching than branching corals. Massive corals surrounded by sand were more affected than the ones surrounded by rubble or dead coral. It is hypothesized that light reflectance from sand increases stress levels experienced by the colonies. This effect is maximized in massive corals as opposed to branching corals that form dense thickets on Heron Island. These results emphasize the importance of the ecological dynamics of coral communities experiencing low, moderate and high levels of bleaching for the understanding of how coral communities may change under the stress of climate change.

  14. Bleaching, disease and recovery in the threatened scleractinian coral Acropora palmata in St. John, US Virgin Islands: 2003-2010

    NASA Astrophysics Data System (ADS)

    Rogers, C. S.; Muller, E. M.

    2012-09-01

    A long-term study of the scleractinian coral Acropora palmata in the US Virgin Islands (USVI) showed that diseases, particularly white pox, are limiting the recovery of this threatened species. Colonies of A. palmata in Haulover Bay, within Virgin Islands National Park, St. John, were examined monthly in situ for signs of disease and other stressors from January 2003 through December 2009. During the study, 89.9 % of the colonies ( n = 69) exhibited disease, including white pox (87 %), white band (13 %), and unknown (9 %). Monthly disease prevalence ranged from 0 to 57 %, and disease was the most significant cause of complete colony mortality ( n = 17). A positive correlation was found between water temperature and disease prevalence, but not incidence. Annual average disease prevalence and incidence remained constant during the study. Colonies generally showed an increase in the estimated amount of total living tissue from growth, but 25 (36.2 %) of the colonies died. Acropora palmata bleached in the USVI for the first time during the 2005 Caribbean bleaching event. Only one of the 23 colonies that bleached appeared to die directly from bleaching. In 2005, corals that bleached had greater disease prevalence than those that did not bleach. Just over half (52 %) of the colonies incurred some physical damage. Monitoring of fragments (broken branches) that were generated by physical damage through June 2007 showed that 46.1 % died and 28.4 % remained alive; the fragments that attached to the substrate survived longer than those that did not. Recent surveys showed an increase in the total number of colonies within the reef area, formed from both asexual and sexual reproduction. Genotype analysis of 48 of the originally monitored corals indicated that 43 grew from sexual recruits supporting the conclusion that both asexual and sexual reproduction are contributing to an increase in colony density at this site.

  15. Bleaching, disease and recovery in the threatened scleractinian coral Acropora palmata in St. John, US Virgin Islands: 2003-2010

    USGS Publications Warehouse

    Rogers, C.S.; Muller, E.M.

    2012-01-01

    A long-term study of the scleractinian coral Acropora palmata in the US Virgin Islands (USVI) showed that diseases, particularly white pox, are limiting the recovery of this threatened species. Colonies of A. palmata in Haulover Bay, within Virgin Islands National Park, St. John, were examined monthly in situ for signs of disease and other stressors from January 2003 through December 2009. During the study, 89.9 % of the colonies (n = 69) exhibited disease, including white pox (87 %), white band (13 %), and unknown (9 %). Monthly disease prevalence ranged from 0 to 57 %, and disease was the most significant cause of complete colony mortality (n = 17). A positive correlation was found between water temperature and disease prevalence, but not incidence. Annual average disease prevalence and incidence remained constant during the study. Colonies generally showed an increase in the estimated amount of total living tissue from growth, but 25 (36.2 %) of the colonies died. Acropora palmata bleached in the USVI for the first time during the 2005 Caribbean bleaching event. Only one of the 23 colonies that bleached appeared to die directly from bleaching. In 2005, corals that bleached had greater disease prevalence than those that did not bleach. Just over half (52 %) of the colonies incurred some physical damage. Monitoring of fragments (broken branches) that were generated by physical damage through June 2007 showed that 46.1 % died and 28.4 % remained alive; the fragments that attached to the substrate survived longer than those that did not. Recent surveys showed an increase in the total number of colonies within the reef area, formed from both asexual and sexual reproduction. Genotype analysis of 48 of the originally monitored corals indicated that 43 grew from sexual recruits supporting the conclusion that both asexual and sexual reproduction are contributing to an increase in colony density at this site.

  16. Reef fish diversity at Aldabra Atoll, Seychelles, during the five years following the 1998 coral bleaching event.

    PubMed

    Downing, Nigel; Buckley, Raymond; Stobart, Ben; Leclair, Larry; Teleki, Kristian

    2005-01-15

    Quantitative surveys of fish-species diversity were undertaken at 10 m and 20 m water depth on the outer reef at Aldabra Atoll, southern Seychelles, between November 1999 and May 2003. No significant changes in total fish-species diversity, numbers of families represented by these species, or numbers of pomacentrid or chaetodontid species were seen, contrary to fish-diversity changes seen on coral bleaching-impacted reefs elsewhere. The lack of additional anthropogenic pressures at remote Aldabara may make this system, and others like it, more tolerant of bleaching-related population changes.

  17. Gene Expression in the Scleractinian Acropora microphthalma Exposed to High Solar Irradiance Reveals Elements of Photoprotection and Coral Bleaching

    PubMed Central

    Starcevic, Antonio; Dunlap, Walter C.; Cullum, John; Shick, J. Malcolm; Hranueli, Daslav; Long, Paul F.

    2010-01-01

    Background The success of tropical reef-building corals depends on the metabolic co-operation between the animal host and the photosynthetic performance of endosymbiotic algae residing within its cells. To examine the molecular response of the coral Acropora microphthalma to high levels of solar irradiance, a cDNA library was constructed by PCR-based suppression subtractive hybridisation (PCR-SSH) from mRNA obtained by transplantation of a colony from a depth of 12.7 m to near-surface solar irradiance, during which the coral became noticeably paler from loss of endosymbionts in sun-exposed tissues. Methodology/Principal Findings A novel approach to sequence annotation of the cDNA library gave genetic evidence for a hypothetical biosynthetic pathway branching from the shikimic acid pathway that leads to the formation of 4-deoxygadusol. This metabolite is a potent antioxidant and expected precursor of the UV-protective mycosporine-like amino acids (MAAs), which serve as sunscreens in coral phototrophic symbiosis. Empirical PCR based evidence further upholds the contention that the biosynthesis of these MAA sunscreens is a ‘shared metabolic adaptation’ between the symbiotic partners. Additionally, gene expression induced by enhanced solar irradiance reveals a cellular mechanism of light-induced coral bleaching that invokes a Ca2+-binding synaptotagmin-like regulator of SNARE protein assembly of phagosomal exocytosis, whereby algal partners are lost from the symbiosis. Conclusions/Significance Bioinformatics analyses of DNA sequences obtained by differential gene expression of a coral exposed to high solar irradiance has revealed the identification of putative genes encoding key steps of the MAA biosynthetic pathway. Revealed also by this treatment are genes that implicate exocytosis as a cellular process contributing to a breakdown in the metabolically essential partnership between the coral host and endosymbiotic algae, which manifests as coral bleaching. PMID

  18. The coral bleaching Vibrio shiloi Kushmaro et al. 2001 is a later synonym of Vibrio mediterranei Pujalte and Garay 1986.

    PubMed

    Thompson, F L; Hoste, B; Thompson, C C; Huys, G; Swings, J

    2001-12-01

    The coral bleaching Vibrio shiloi LMG 19703T was characterized by means of Fluorescent Amplified Fragment Length Polymorphism (FAFLP), DNA-DNA hybridisation, mol% G+C content, fatty acids methyl ester (FAME) analysis and phenotypical tests. Numerical analysis of the FAFLP band patterns indicated that the type strain of V. shiloi in fact belongs to the species V. mediterranei. The type strains of both species shared 77% DNA similarity, as determined by DNA-DNA hybridisation experiments at stringent conditions. Moreover, V. shiloi and V. mediterranei showed almost identical fatty acid composition and phenotypical features. Collectively, the genotypic and phenotypic data presented in this study suggest that V. shiloi Kushmaro et al. 2001 should be considered a later synonym of V. mediterranei Pujalte and Garay 1986. The involvement of V. mediterranei in coral bleaching was unknown until now.

  19. Heat-stress and light-stress induce different cellular pathologies in the symbiotic dinoflagellate during coral bleaching.

    PubMed

    Downs, C A; McDougall, Kathleen E; Woodley, Cheryl M; Fauth, John E; Richmond, Robert H; Kushmaro, Ariel; Gibb, Stuart W; Loya, Yossi; Ostrander, Gary K; Kramarsky-Winter, Esti

    2013-01-01

    Coral bleaching is a significant contributor to the worldwide degradation of coral reefs and is indicative of the termination of symbiosis between the coral host and its symbiotic algae (dinoflagellate; Symbiodinium sp. complex), usually by expulsion or xenophagy (symbiophagy) of its dinoflagellates. Herein, we provide evidence that during the earliest stages of environmentally induced bleaching, heat stress and light stress generate distinctly different pathomorphological changes in the chloroplasts, while a combined heat- and light-stress exposure induces both pathomorphologies; suggesting that these stressors act on the dinoflagellate by different mechanisms. Within the first 48 hours of a heat stress (32°C) under low-light conditions, heat stress induced decomposition of thylakoid structures before observation of extensive oxidative damage; thus it is the disorganization of the thylakoids that creates the conditions allowing photo-oxidative-stress. Conversely, during the first 48 hours of a light stress (2007 µmoles m(-2) s(-1) PAR) at 25°C, condensation or fusion of multiple thylakoid lamellae occurred coincidently with levels of oxidative damage products, implying that photo-oxidative stress causes the structural membrane damage within the chloroplasts. Exposure to combined heat- and light-stresses induced both pathomorphologies, confirming that these stressors acted on the dinoflagellate via different mechanisms. Within 72 hours of exposure to heat and/or light stresses, homeostatic processes (e.g., heat-shock protein and anti-oxidant enzyme response) were evident in the remaining intact dinoflagellates, regardless of the initiating stressor. Understanding the sequence of events during bleaching when triggered by different environmental stressors is important for predicting both severity and consequences of coral bleaching.

  20. Heat-Stress and Light-Stress Induce Different Cellular Pathologies in the Symbiotic Dinoflagellate during Coral Bleaching

    PubMed Central

    Downs, C. A.; McDougall, Kathleen E.; Woodley, Cheryl M.; Fauth, John E.; Richmond, Robert H.; Kushmaro, Ariel; Gibb, Stuart W.; Loya, Yossi; Ostrander, Gary K.; Kramarsky-Winter, Esti

    2013-01-01

    Coral bleaching is a significant contributor to the worldwide degradation of coral reefs and is indicative of the termination of symbiosis between the coral host and its symbiotic algae (dinoflagellate; Symbiodinium sp. complex), usually by expulsion or xenophagy (symbiophagy) of its dinoflagellates. Herein, we provide evidence that during the earliest stages of environmentally induced bleaching, heat stress and light stress generate distinctly different pathomorphological changes in the chloroplasts, while a combined heat- and light-stress exposure induces both pathomorphologies; suggesting that these stressors act on the dinoflagellate by different mechanisms. Within the first 48 hours of a heat stress (32°C) under low-light conditions, heat stress induced decomposition of thylakoid structures before observation of extensive oxidative damage; thus it is the disorganization of the thylakoids that creates the conditions allowing photo-oxidative-stress. Conversely, during the first 48 hours of a light stress (2007 µmoles m−2 s−1 PAR) at 25°C, condensation or fusion of multiple thylakoid lamellae occurred coincidently with levels of oxidative damage products, implying that photo-oxidative stress causes the structural membrane damage within the chloroplasts. Exposure to combined heat- and light-stresses induced both pathomorphologies, confirming that these stressors acted on the dinoflagellate via different mechanisms. Within 72 hours of exposure to heat and/or light stresses, homeostatic processes (e.g., heat-shock protein and anti-oxidant enzyme response) were evident in the remaining intact dinoflagellates, regardless of the initiating stressor. Understanding the sequence of events during bleaching when triggered by different environmental stressors is important for predicting both severity and consequences of coral bleaching. PMID:24324575

  1. Photosystem II recovery in the presence and absence of chloroplast protein repair in the symbionts of corals exposed to bleaching conditions

    NASA Astrophysics Data System (ADS)

    Hill, R.; Takahashi, S.

    2014-12-01

    Increased seawater temperature causes photoinhibition due to accumulation of photodamaged photosystem II (PSII) in symbiotic algae (genus Symbiodinium) within corals, and it is assumed to be associated with coral bleaching. To avoid photoinhibition, photosynthetic organisms repair the photodamaged PSII through replacing the PSII proteins, primarily the D1 protein, with newly synthesised proteins. However, in experiments using cultured Symbiodinium strains, the PSII repair of Symbiodinium has been suggested not to be related to the synthesis of the D1 protein. In this study, we examined the relationship between the recovery of PSII photochemical efficiency ( F V/ F M) and the content of D1 protein after high-light and high-temperature treatments using the bleaching-sensitive coral species, Pocillopora damicornis and Acropora millepora, and the bleaching-tolerant coral species, Montipora digitata and Pavona decussata. When corals were exposed to strong light (600 µmol photons m-2 s-1) at elevated temperature (32 °C) for 8 h, significant bleaching occurred in bleaching-sensitive coral species although an almost similar extent of reduced PSII function was found across all coral species tested. During a subsequent 15-h recovery under low light (10 µmol photons m-2 s-1) at optimal temperature (22 °C), the reduced F V/ F M recovered close to initial levels in all coral species, but the reduced D1 content recovered only in one coral species ( Pavona decussata). D1 content was therefore not strongly linked to chloroplast protein synthesis-dependent PSII repair. These results demonstrate that the recovery of photodamaged PSII does not always correspond with the recovery of D1 protein content in Symbiodinium within corals, suggesting that photodamaged PSII can be repaired by a unique mechanism in Symbiodinium within corals.

  2. Stable Oxygen (δ 18O) and Carbon (δ 13C) Isotopes in the Skeleton of Bleached and Recovering Corals From Hawaii

    NASA Astrophysics Data System (ADS)

    Rodrigues, L. J.; Grottoli, A. G.

    2004-12-01

    Coral skeletal stable oxygen isotopes (δ 18O) reflect changes in seawater temperature and salinity, while stable carbon isotopes (δ 13C) reflect a combination of both metabolic (photosynthesis and feeding) and kinetic fractionation. Together, the two isotopic signatures may be used as a proxy for past bleaching events. During bleaching, increased seawater temperatures often contribute to a decline in zooxanthellae and/or chlorophyll concentrations, resulting in a decrease in photosynthesis. We experimentally investigated the effect of bleaching and subsequent recovery on the δ 13C and δ 18O values of coral skeleton. Fragments from two coral species (Montipora capitata and Porites compressa) from Kaneohe Bay, Hawaii were bleached in outdoor tanks by raising the seawater temperature to 30° C. Additional fragments from the same parent colonies were maintained at ambient seawater temperatures (27° C) in separate tanks as controls. After one month in the tanks, a subset of the fragments was frozen and all remaining fragments were placed back on the reef to recover. All coral fragments were analyzed for their skeletal δ 13C and δ 18O compositions at five time intervals: before, immediately after, 1.5, 4, and 8 months after bleaching. In addition, rates of photosynthesis, calcification, and heterotrophy were also measured. Immediately after bleaching, δ 18O decreased in bleached M. capitata relative to controls, reflecting their exposure to increased seawater temperatures. During recovery, δ 18O values in the treatment M. capitata were not different from the controls. In P. compressa, δ 18O did not significantly differ in bleached and control corals at any time during the experiment. Immediately after bleaching, δ 13C decreased in the bleached fragments of both species relative to controls reflecting decreased photosynthetic rates. However, during recovery δ 13C in both species was greater in bleached than control fragments despite photosynthesis remaining

  3. Recovery from bleaching is mediated by threshold densities of background thermo-tolerant symbiont types in a reef-building coral

    PubMed Central

    Bay, Line K.; Doyle, Jason; Logan, Murray; Berkelmans, Ray

    2016-01-01

    Sensitive molecular analyses show that most corals host a complement of Symbiodinium genotypes that includes thermo-tolerant types in low abundance. While tolerant symbiont types are hypothesized to facilitate tolerance to temperature and recovery from bleaching, empirical data on their distribution and relative abundance in corals under ambient and stress conditions are still rare. We quantified visual bleaching and mortality of coral hosts, along with relative abundance of C- and D-type Symbiodinium cells in 82 Acropora millepora colonies from three locations on the Great Barrier Reef transplanted to a central inshore site over a 13 month period. Our analyses reveal dynamic change in symbiont associations within colonies and among populations over time. Coral bleaching and declines in C- but not D-type symbionts were observed in transplanted corals. Survival and recovery of 25% of corals from one population was associated with either initial D-dominance or an increase in D-type symbionts that could be predicted by a minimum pre-stress D : C ratio of 0.003. One-third of corals from this population became D dominated at the bleached stage despite no initial detection of this symbiont type, but failed to recover and died in mid to late summer. These results provide a predictive threshold minimum density of background D-type symbionts in A. millepora, above which survival following extreme thermal stress is increased. PMID:27429786

  4. Recovery from bleaching is mediated by threshold densities of background thermo-tolerant symbiont types in a reef-building coral.

    PubMed

    Bay, Line K; Doyle, Jason; Logan, Murray; Berkelmans, Ray

    2016-06-01

    Sensitive molecular analyses show that most corals host a complement of Symbiodinium genotypes that includes thermo-tolerant types in low abundance. While tolerant symbiont types are hypothesized to facilitate tolerance to temperature and recovery from bleaching, empirical data on their distribution and relative abundance in corals under ambient and stress conditions are still rare. We quantified visual bleaching and mortality of coral hosts, along with relative abundance of C- and D-type Symbiodinium cells in 82 Acropora millepora colonies from three locations on the Great Barrier Reef transplanted to a central inshore site over a 13 month period. Our analyses reveal dynamic change in symbiont associations within colonies and among populations over time. Coral bleaching and declines in C- but not D-type symbionts were observed in transplanted corals. Survival and recovery of 25% of corals from one population was associated with either initial D-dominance or an increase in D-type symbionts that could be predicted by a minimum pre-stress D : C ratio of 0.003. One-third of corals from this population became D dominated at the bleached stage despite no initial detection of this symbiont type, but failed to recover and died in mid to late summer. These results provide a predictive threshold minimum density of background D-type symbionts in A. millepora, above which survival following extreme thermal stress is increased.

  5. Photobacterium rosenbergii sp. nov. and Enterovibrio coralii sp. nov., vibrios associated with coral bleaching.

    PubMed

    Thompson, F L; Thompson, C C; Naser, S; Hoste, B; Vandemeulebroecke, K; Munn, C; Bourne, D; Swings, J

    2005-03-01

    Six new Vibrio-like isolates originating from different species of bleached and healthy corals around Magnetic Island (Australia) were investigated using a polyphasic approach. Phylogenetic analyses based on 16S rRNA, recA and rpoA gene sequences split the isolates in two new groups. Strains LMG 22223(T), LMG 22224, LMG 22225, LMG 22226 and LMG 22227 were phylogenetic neighbours of Photobacterium leiognathi LMG 4228(T) (95.6 % 16S rRNA gene sequence similarity), whereas strain LMG 22228(T) was related to Enterovibrio norvegicus LMG 19839(T) (95.5 % 16S rRNA gene sequence similarity). The two new groups can be distinguished from closely related species on the basis of several phenotypic features, including fermentation of d-mannitol, melibiose and sucrose, and utilization of different compounds as carbon sources, arginine dihydrolase activity, nitrate reduction, resistance to the vibriostatic agent O/129 and the presence of fatty acids 15 : 0 iso and 17 : 0 iso. The names Photobacterium rosenbergii sp. nov. (type strain LMG 22223(T)=CBMAI 622(T)=CC1(T)) and Enterovibrio coralii sp. nov. (type strain LMG 22228(T)=CBMAI 623(T)=CC17(T)) are proposed to accommodate these new isolates. The G+C contents of the DNA of the two type strains are respectively 47.6 and 48.2 mol%.

  6. The role of human-induced climate change in the 2005 Caribbean coral bleaching event and the implications for the future

    NASA Astrophysics Data System (ADS)

    Donner, S. D.; Knutson, T. R.; Oppenheimer, M.

    2007-12-01

    Episodes of mass coral bleaching in recent decades have been attributed to periods of anomalously warm ocean temperatures. In 2005, the sea surface temperature (SST) anomaly in the tropical North Atlantic that contributed to the strong hurricane season caused widespread coral bleaching in the eastern Caribbean. In this study, we used the GFDL global climate models to evaluate the contribution of natural climate variability and anthropogenic forcing to the thermal stress that caused the 2005 coral bleaching event. Historical temperature data and simulations for the 1870-2000 period show that the observed warming in the region is unlikely to be due to unforced climate variability alone. Simulation of background climate variability suggests that anthropogenic warming may have increased the probability of occurrence of significant thermal stress events for corals in this region by an order of magnitude. Under scenarios of future greenhouse gas emissions, mass coral bleaching in the eastern Caribbean may become a biannual event in 20-30 years. However, if corals and their symbionts can adapt by 1 - 1.5°C, such mass bleaching events may not begin to recur at potentially harmful intervals until the latter half of the century. The delay could enable more time to alter the path of greenhouse gas emissions, although long-term "committed warming" even after stabilization of atmospheric CO2 levels may still represent an additional long-term threat to corals. These results suggest that protecting coral reefs from climate change will require both managing local pressures on reefs, in order to increase resilience to committed warming, and reducing greenhouse gas emissions.

  7. Species-specific responses of corals to bleaching events on anthropogenically turbid reefs on Okinawa Island, Japan, over a 15-year period (1995-2009).

    PubMed

    Hongo, Chuki; Yamano, Hiroya

    2013-01-01

    Coral bleaching, triggered by elevated sea-surface temperatures (SSTs) has caused a decline in coral cover and changes in the abundances of corals on reefs worldwide. Coral decline can be exacerbated by the effects of local stressors like turbidity, yet some reefs with a natural history of turbidity can support healthy and resilient coral communities. However, little is known about responses of coral communities to bleaching events on anthropogenically turbid reefs as a result of recent (post World War II) terrestrial runoff. Analysis of region-scale coral cover and species abundance at 17-20 sites on the turbid reefs of Okinawa Island (total of 79 species, 30 genera, and 13 families) from 1995 to 2009 indicates that coral cover decreased drastically, from 24.4% to 7.5% (1.1%/year), subsequent to bleaching events in 1998 and 2001. This dramatic decrease in coral cover corresponded to the demise of Acropora species (e.g., A. digitifera) by 2009, when Acropora had mostly disappeared from turbid reefs on Okinawa Island. In contrast, Merulinidae species (e.g., Dipsastraea pallida/speciosa/favus) and Porites species (e.g., P. lutea/australiensis), which are characterized by tolerance to thermal stress, survived on turbid reefs of Okinawa Island throughout the period. Our results suggest that high turbidity, influenced by recent terrestrial runoff, could have caused a reduction in resilience of Acropora species to severe thermal stress events, because the corals could not have adapted to a relatively recent decline in water quality. The coral reef ecosystems of Okinawa Island will be severely impoverished if Acropora species fail to recover.

  8. Air-sea energy exchanges measured by eddy covariance during a localised coral bleaching event, Heron Reef, Great Barrier Reef, Australia

    NASA Astrophysics Data System (ADS)

    MacKellar, Mellissa C.; McGowan, Hamish A.

    2010-12-01

    Despite the widely claimed association between climate change and coral bleaching, a paucity of data exists relating to exchanges of heat, moisture and momentum between the atmosphere and the reef-water surface. We present in situ measurements of reef-water-air energy exchanges made using the eddy covariance method during a summer coral bleaching event at Heron Reef, Australia. Under settled, cloud-free conditions and light winds, daily net radiation exceeded 800 W m-2, with up to 95% of the net radiation during the morning partitioned into heating the water column, substrate and benthic cover including corals. Heating was exacerbated by a mid-afternoon low tide when shallow reef flat water reached 34°C and near-bottom temperatures 33°C, exceeding the thermal tolerance of corals, causing bleaching. Results suggest that local to synoptic scale meteorology, particularly clear skies, solar heating, light winds and the timing of low tide were the primary controls on coral bleaching.

  9. Experimental Bleaching of a Reef-Building Coral Using a Simplified Recirculating Laboratory Exposure System

    EPA Science Inventory

    Determining stressor-response relationships in reef building corals is a critical need for researchers because of global declines in coral reef ecosystems. A simplified recirculating coral exposure system for laboratory testing of a diversity of species and morphologies of reef b...

  10. Atmospheric forcing intensifies the effects of regional ocean warming on reef-scale temperature anomalies during a coral bleaching event

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenlin; Falter, James; Lowe, Ryan; Ivey, Greg; McCulloch, Malcolm

    2013-09-01

    We investigate how local atmospheric conditions and hydrodynamic forcing contributed to local variations in water temperature within a fringing coral reef-lagoon system during the peak of a marine heat wave in 2010-2011 that caused mass coral bleaching across Western Australia. A three-dimensional circulation model Regional Ocean Modeling System (ROMS) with a built-in air-sea heat flux exchange module Coupled Ocean Atmosphere Experiment (COARE) was coupled with a spectral wave model Simulating Waves Nearshore (SWAN) to resolve the surface heat exchange and wave-driven reef circulation in Coral Bay, Ningaloo Reef. Using realistic oceanic and atmospheric forcing, the model predictions were in good agreement with measured time series of water temperature at various locations in the coral reef system during the bleaching event. Through a series of sensitivity analyses, we found that the difference in temperature between the reef and surrounding offshore waters (ΔT) was predominantly a function of both the daily mean net heat flux (Qnet>¯) and residence time, whereas diurnal variations in reef water temperature were dependent on the diurnal fluctuation in the net heat flux. We found that reef temperatures were substantially higher than offshore in the inner lagoon under normal weather conditions and over the entire reef domain under more extreme weather conditions (0.7°C-1.5°C). Although these temperature elevations were still less than that caused by the regional ocean warming (2°C-3°C), the arrival of peak seasonal temperatures in the summer of 2010-2011 (when net atmospheric heat fluxes were positive and abnormally high) caused substantially higher thermal stresses than would have otherwise occurred if offshore temperatures had reached their normal seasonal maxima in autumn (when net atmospheric heat fluxes were negative or cooling). Therefore, the degree heating weeks calculated based on offshore temperature substantially underestimated the thermal stresses

  11. Nitric oxide mediates coral bleaching through an apoptotic-like cell death pathway: evidence from a model sea anemone-dinoflagellate symbiosis.

    PubMed

    Hawkins, Thomas D; Bradley, Benjamin J; Davy, Simon K

    2013-12-01

    Coral bleaching (involving the loss of symbiotic algae from the cnidarian host) is a major threat to coral reefs and appears to be mediated at the cellular level by nitric oxide (NO). In this study, we examined the specific role of NO in bleaching using the sea anemone Aiptasia pulchella, a model system for the study of corals. Exposure of A. pulchella to high-temperature shock (26-33°C over <1 h) or an NO donor (S-nitrosoglutathione) resulted in significant increases in host caspase-like enzyme activity. These responses were reflected in the intensities of bleaching, which were significantly higher in heat- or NO-treated specimens than in controls maintained in seawater at 26°C. Notably, the inhibition of caspase-like activity prevented bleaching even in the presence of an NO donor or at elevated temperature. The additional use of an NO scavenger controlled for effects mediated by agents other than NO. We also exposed A. pulchella to a more ecologically relevant treatment (an increase from 26 to 33°C over 6-7 d). Again, host NO synthesis correlated with the activation of caspase-like enzyme activity. Therefore, we conclude that NO's involvement in cnidarian bleaching arises through the regulation of host apoptotic pathways.

  12. Coral bleaching, hurricane damage, and benthic cover on coral reefs in St. John, U.S. Virgin Islands: A comparison of surveys with the chain transect method and videography

    USGS Publications Warehouse

    Rogers, C.S.; Miller, J.

    2001-01-01

    The linear chain transect method and videography were used to quantify the percent cover by corals, macroalgae, gorgonians, other living organisms, and substrate along permanent transects on two fringing reefs off St. John. Both methods were used simultaneously on Lameshur reef in November 1998, and on Newfound reef in March and October 1998. Hurricane Georges passed over St. John in September 1998, and a severe coral bleaching episode began the same month. Both methods gave remarkably similar values for coral cover, while the video method gave consistently higher values for gorgonians and macroalgae. The most dramatic difference was in the quantification of bleaching. At Newfound, the chain method indicated 13.4% (SD = 14.1) of the coral tissues were bleached and the video method, 43.4% (SD = 13.0). Corresponding values at Lameshur were 18.1% (SD = 22.3) and 46.5% (SD = 13.3). Although hurricane damage was conspicuous at Newfound reef, neither method showed significant changes in coral cover or other categories as a result of the storm.

  13. Nitric oxide and heat shock protein 90 co-regulate temperature-induced bleaching in the soft coral Eunicea fusca

    NASA Astrophysics Data System (ADS)

    Ross, Cliff

    2014-06-01

    Coral bleaching represents a complex physiological process that is affected not only by environmental conditions but by the dynamic internal cellular biology of symbiotic dinoflagellates ( Symbiodinium spp.) and their cnidarian hosts. Recently, nitric oxide (NO) has emerged as a key molecule involved with the expulsion of Symbiodinium from host cnidarian cells. However, the site of production remains under debate, and the corresponding signaling pathways within and between host and endosymbiont remain elusive. In this study, using freshly isolated Symbiodinium from the soft coral Eunicea fusca, I demonstrate that thermally induced stress causes an upregulation in Symbiodinium heat shock protein 90 (Hsp90). In turn, Hsp90 shows a concomitant ability to enhance the activity of a constitutively expressed isoform of NO synthase. The resulting production of NO constitutes a signaling molecule capable of inducing Symbiodinium expulsion. Using nitric oxide synthase (NOS) and Hsp90 polyclonal antibodies, thermal stress-induced Hsp90 was shown to co-immunoprecipitate with a constitutive isoform of NOS. The specific blocking of Hsp90 activity, with the Hsp90 inhibitor geldanamycin, was capable of inhibiting NO production implicating the involvement of a coordinated regulatory system. These results have strong evolutionary implications for Hsp90-NOS chaperone complexes among biological kingdoms and provide evidence for a new functional role in symbiotic associations.

  14. Heat stress stimulates nitric oxide production in Symbiodinium microadriaticum: a possible linkage between nitric oxide and the coral bleaching phenomenon.

    PubMed

    Bouchard, Josée Nina; Yamasaki, Hideo

    2008-04-01

    Nitric oxide (NO) is a gas displaying multiple physiological functions in plants, animals and bacteria. The enzymes nitrate reductase and NO synthase have been suggested to be involved in the production of NO in plants and algae, but the implication of those enzymes in NO production under physiological conditions remains obscure. Symbiodinium microadriaticum, commonly referred to as zooxanthellae, is a marine microalga commonly found in symbiotic association with a cnidarian host including reef-building corals. Here we demonstrate NO production in zooxanthellae upon supplementation of either sodium nitrite or L-arginine as a substrate. The nitrite-dependent NO production was detected electrochemically and confirmed by the application of 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), a specific NO scavenger. Cells stained with the diaminofluorescein, DAF-2 DA, an NO fluorescent probe, showed an increase in fluorescence intensity upon supplementation of both sodium nitrite and L-arginine. Microscopic observations of DAF-stained cells verified that NO was produced inside the cells. NO production in S. microadriaticum was found to increase upon exposure of cells to an acute heat stress which also caused a decline in the photosynthetic efficiency of PSII (F(v)/F(m)). This study provides substantial evidence to confirm that zooxanthellae can synthesize NO even when they are not in a symbiotic association with a coral host. The increase in NO production at high temperatures suggests that heat stress stimulates the microalgal NO production in a temperature-dependent manner. The implications of these findings are discussed in the light of the coral bleaching phenomenon which is associated with elevated sea surface temperature due to global warming.

  15. Proteomics links the redox state to calcium signaling during bleaching of the scleractinian coral Acropora microphthalma on exposure to high solar irradiance and thermal stress.

    PubMed

    Weston, Andrew J; Dunlap, Walter C; Beltran, Victor H; Starcevic, Antonio; Hranueli, Daslav; Ward, Malcolm; Long, Paul F

    2015-03-01

    Shipboard experiments were each performed over a 2 day period to examine the proteomic response of the symbiotic coral Acropora microphthalma exposed to acute conditions of high temperature/low light or high light/low temperature stress. During these treatments, corals had noticeably bleached. The photosynthetic performance of residual algal endosymbionts was severely impaired but showed signs of recovery in both treatments by the end of the second day. Changes in the coral proteome were determined daily and, using recently available annotated genome sequences, the individual contributions of the coral host and algal endosymbionts could be extracted from these data. Quantitative changes in proteins relevant to redox state and calcium metabolism are presented. Notably, expression of common antioxidant proteins was not detected from the coral host but present in the algal endosymbiont proteome. Possible roles for elevated carbonic anhydrase in the coral host are considered: to restore intracellular pH diminished by loss of photosynthetic activity, to indirectly limit intracellular calcium influx linked with enhanced calmodulin expression to impede late-stage symbiont exocytosis, or to enhance inorganic carbon transport to improve the photosynthetic performance of algal symbionts that remain in hospite. Protein effectors of calcium-dependent exocytosis were present in both symbiotic partners. No caspase-family proteins associated with host cell apoptosis, with exception of the autophagy chaperone HSP70, were detected, suggesting that algal loss and photosynthetic dysfunction under these experimental conditions were not due to host-mediated phytosymbiont destruction. Instead, bleaching occurred by symbiont exocytosis and loss of light-harvesting pigments of algae that remain in hospite. These proteomic data are, therefore, consistent with our premise that coral endosymbionts can mediate their own retention or departure from the coral host, which may manifest as

  16. Neutralization of radical toxicity by temperature-dependent modulation of extracellular SOD activity in coral bleaching pathogen Vibrio shiloi and its role as a virulence factor.

    PubMed

    Murali, Malliga Raman; Raja, Subramaniya Bharathi; Devaraj, Sivasitambaram Niranjali

    2010-08-01

    Vibrio shiloi is the first and well-documented bacterium which causes coral bleaching, particularly, during summer, when seawater temperature is between 26 and 31 degrees C. Coral bleaching is the disruption of the symbiotic association between coral hosts and their photosynthetic microalgae zooxanthellae. This is either due to lowered resistance in corals to infection or increased virulence of the bacterium at the higher sea surface temperature. The concentration of the oxygen and resulting oxygen radicals produced by the zooxanthellae during photosynthesis are highly toxic to bacteria, which also assist corals in resisting the infection. Hence, in this study we examined the effect of different temperatures on the activity of a novel extracellular SOD in V. shiloi. We also partially characterized the SOD and clearly confirmed that the extracellular SOD produced by V. shiloi is Mn-SOD type, as it was not inhibited by H2O2 or KCN. Performing chemical susceptibility killing assay, we confirmed that extracellular SOD may act as first line of defense for the bacteria against the reactive oxygen species. Since, increased activity of novel Mn-SOD at higher temperature, leads to the neutralization of radical toxicity and facilitates the survival of V. shiloi. Hence, the extracellular Mn-SOD may be considered as a virulence factor.

  17. Differential bleaching of corals based on El Niño type and intensity in the Andaman Sea, southeast Bay of Bengal.

    PubMed

    Lix, J K; Venkatesan, R; Grinson, George; Rao, R R; Jineesh, V K; Arul, Muthiah M; Vengatesan, G; Ramasundaram, S; Sundar, R; Atmanand, M A

    2016-03-01

    The Andaman coral reef region experienced mass bleaching events during 1998 and 2010. The purpose of this study is to investigate the role of the El Niño in the coral reef bleaching events of the Andaman region. Both Niño 3.4 and 3 indices were examined to find out the relationship between the mass bleaching events and El Niño, and correlated with sea surface temperature (SST) anomalies in the Andaman Sea. The result shows that abnormal warming and mass bleaching events in the Andaman Sea were seen only during strong El Niño years of 1997-1998 and 2009-2010. The Andaman Sea SST was more elevated and associated with El Niño Modoki (central Pacific El Niño) than conventional El Niño (eastern Pacific El Niño) occurrences. It is suggested that the development of hot spot patterns around the Andaman Islands during May 1998 and April-May 2010 may be attributed to zonal shifts in the Walker circulation driven by El Niño during the corresponding period.

  18. Species Specificity of Bacteria Associated to the Brown Seaweeds Lobophora (Dictyotales, Phaeophyceae) and Their Potential for Induction of Rapid Coral Bleaching in Acropora muricata

    PubMed Central

    Vieira, Christophe; Engelen, Aschwin H.; Guentas, Linda; Aires, Tânia; Houlbreque, Fanny; Gaubert, Julie; Serrão, Ester A.; De Clerck, Olivier; Payri, Claude E.

    2016-01-01

    While reef degradation is occurring worldwide, it is not uncommon to see phase shifts from coral to macroalgal dominated reefs. Numerous studies have addressed the mechanisms by which macroalgae may outcompete corals and a few recent studies highlighted the putative role of bacteria at the interface between macroalgae and corals. Some studies suggest that macroalgae may act as vectors and/or foster proliferation of microorganisms pathogenic for corals. Using a combination of high throughput sequencing, bacterial culturing, and in situ bioassays we question if the adversity of macroalgal-associated bacteria to corals is mediated by specific bacterial taxa. Using Illumina sequencing, we characterized and compared the bacterial community from two Lobophora (Dictyotales, Phaeophyceae) species. The two species presented distinctive bacterial communities. Both species shared approximately half of their OTUs, mainly the most abundant bacteria. Species-specific OTUs belong to Planctomycetes, Proteobacteria, and Bacteroidetes. In total, 16 culturable bacterial strain were isolated and identified from the Lobophora surface, consisting of 10 genera (from nine families, four classes, and three phyla), some of which are not known as, but are related to pathogens involved in coral diseases, and others are naturally associated to corals. When patches of marine agar with 24 h cultures of each of these bacteria were placed in direct contact with the branches of the scleractinian coral Acropora muricata, they caused severe bleaching after 24 h exposure. Results suggest that regardless of taxonomic affinities, increase in density of these bacteria can be adverse to corals. Nevertheless, the microbial community associated to macroalgal surface may not represent a threat to corals, because the specific bacterial screening and control exerted by the alga preventing specific bacterial proliferation. PMID:27047453

  19. Species Specificity of Bacteria Associated to the Brown Seaweeds Lobophora (Dictyotales, Phaeophyceae) and Their Potential for Induction of Rapid Coral Bleaching in Acropora muricata.

    PubMed

    Vieira, Christophe; Engelen, Aschwin H; Guentas, Linda; Aires, Tânia; Houlbreque, Fanny; Gaubert, Julie; Serrão, Ester A; De Clerck, Olivier; Payri, Claude E

    2016-01-01

    While reef degradation is occurring worldwide, it is not uncommon to see phase shifts from coral to macroalgal dominated reefs. Numerous studies have addressed the mechanisms by which macroalgae may outcompete corals and a few recent studies highlighted the putative role of bacteria at the interface between macroalgae and corals. Some studies suggest that macroalgae may act as vectors and/or foster proliferation of microorganisms pathogenic for corals. Using a combination of high throughput sequencing, bacterial culturing, and in situ bioassays we question if the adversity of macroalgal-associated bacteria to corals is mediated by specific bacterial taxa. Using Illumina sequencing, we characterized and compared the bacterial community from two Lobophora (Dictyotales, Phaeophyceae) species. The two species presented distinctive bacterial communities. Both species shared approximately half of their OTUs, mainly the most abundant bacteria. Species-specific OTUs belong to Planctomycetes, Proteobacteria, and Bacteroidetes. In total, 16 culturable bacterial strain were isolated and identified from the Lobophora surface, consisting of 10 genera (from nine families, four classes, and three phyla), some of which are not known as, but are related to pathogens involved in coral diseases, and others are naturally associated to corals. When patches of marine agar with 24 h cultures of each of these bacteria were placed in direct contact with the branches of the scleractinian coral Acropora muricata, they caused severe bleaching after 24 h exposure. Results suggest that regardless of taxonomic affinities, increase in density of these bacteria can be adverse to corals. Nevertheless, the microbial community associated to macroalgal surface may not represent a threat to corals, because the specific bacterial screening and control exerted by the alga preventing specific bacterial proliferation.

  20. Bleaching in coral reef anthozoans: effects of irradiance, ultraviolet radiation, and temperature on the activities of protective enzymes against active oxygen

    NASA Astrophysics Data System (ADS)

    Lesser, M. P.; Stochaj, W. R.; Tapley, D. W.; Shick, J. M.

    1990-04-01

    Recent widespread bleaching of coral reef anthozoans has been observed on the Great Barrier Reef, the Pacific coast of Panama, and in the Caribbean Sea. Bleaching events have been correlated with anomalously high sea surface temperatures which are presumed to cause the expulsion of zooxanthellae from their hosts. Our experimental results show that increases in temperature significantly reduce the total number of zooxanthellae per polyp. At the same time temperature, irradiance (photosynthetically active radiation=PAR), and ultraviolet radiation (UV) independently increase the activities of the enzymes superoxide dismutase, catalase, and ascorbate peroxidase within the zooxanthellae of the zoanthid Palythoa caribaeorum. Enzyme activities within the host are only suggestive of similar changes. These enzymes are responsible for detoxifying active forms of oxygen, and their elevated activities indirectly indicate an increase in the production of active oxygen species by increases in these environmental factors. Historically, bleaching has been attributed to changes in temperature, salinity, and UV. Increases in temperature or highly energetic UV radiation can increase the flux of active forms of oxygen, particularly at the elevated oxygen concentrations that prevail in the tissues during photosynthesis, with oxygen toxicity potentially mediating the bleaching event. Additionally, the concentration of UV absorbing compounds within the symbiosis is inversely related to temperature, potentially increasing exposure of the host and zooxanthellae to the direct effects of UV.

  1. Assessing the Effects of Disease and Bleaching on Florida Keys Corals by Fitting Population Models to Data

    EPA Science Inventory

    Coral diseases have increased in frequency over the past few decades and have important influences on the structure and composition of coral reef communities. However, there is limited information on the etiologies of many coral diseases, and pathways via which coral diseases ar...

  2. Viral Outbreak in Corals Associated with an In Situ Bleaching Event: Atypical Herpes-Like Viruses and a New Megavirus Infecting Symbiodinium

    PubMed Central

    Correa, Adrienne M. S.; Ainsworth, Tracy D.; Rosales, Stephanie M.; Thurber, Andrew R.; Butler, Christopher R.; Vega Thurber, Rebecca L.

    2016-01-01

    Previous studies of coral viruses have employed either microscopy or metagenomics, but few have attempted to comprehensively link the presence of a virus-like particle (VLP) to a genomic sequence. We conducted transmission electron microscopy imaging and virome analysis in tandem to characterize the most conspicuous viral types found within the dominant Pacific reef-building coral genus Acropora. Collections for this study inadvertently captured what we interpret as a natural outbreak of viral infection driven by aerial exposure of the reef flat coincident with heavy rainfall and concomitant mass bleaching. All experimental corals in this study had high titers of viral particles. Three of the dominant VLPs identified were observed in all tissue layers and budding out from the epidermis, including viruses that were ∼70, ∼120, and ∼150 nm in diameter; these VLPs all contained electron dense cores. These morphological traits are reminiscent of retroviruses, herpesviruses, and nucleocytoplasmic large DNA viruses (NCLDVs), respectively. Some 300–500 nm megavirus-like VLPs also were observed within and associated with dinoflagellate algal endosymbiont (Symbiodinium) cells. Abundant sequence similarities to a gammaretrovirus, herpesviruses, and members of the NCLDVs, based on a virome generated from five Acropora aspera colonies, corroborated these morphology-based identifications. Additionally sequence similarities to two diagnostic genes, a MutS and (based on re-annotation of sequences from another study) a DNA polymerase B gene, most closely resembled Pyramimonas orientalis virus, demonstrating the association of a cosmopolitan megavirus with Symbiodinium. We also identified several other virus-like particles in host tissues, along with sequences phylogenetically similar to circoviruses, phages, and filamentous viruses. This study suggests that viral outbreaks may be a common but previously undocumented component of natural bleaching events, particularly

  3. Effects of cold stress and heat stress on coral fluorescence in reef-building corals

    PubMed Central

    Roth, Melissa S.; Deheyn, Dimitri D.

    2013-01-01

    Widespread temperature stress has caused catastrophic coral bleaching events that have been devastating for coral reefs. Here, we evaluate whether coral fluorescence could be utilized as a noninvasive assessment for coral health. We conducted cold and heat stress treatments on the branching coral Acropora yongei, and found that green fluorescent protein (GFP) concentration and fluorescence decreased with declining coral health, prior to initiation of bleaching. Ultimately, cold-treated corals acclimated and GFP concentration and fluorescence recovered. In contrast, heat-treated corals eventually bleached but showed strong fluorescence despite reduced GFP concentration, likely resulting from the large reduction in shading from decreased dinoflagellate density. Consequently, GFP concentration and fluorescence showed distinct correlations in non-bleached and bleached corals. Green fluorescence was positively correlated with dinoflagellate photobiology, but its closest correlation was with coral growth suggesting that green fluorescence could be used as a physiological proxy for health in some corals. PMID:23478289

  4. Effects of cold stress and heat stress on coral fluorescence in reef-building corals.

    PubMed

    Roth, Melissa S; Deheyn, Dimitri D

    2013-01-01

    Widespread temperature stress has caused catastrophic coral bleaching events that have been devastating for coral reefs. Here, we evaluate whether coral fluorescence could be utilized as a noninvasive assessment for coral health. We conducted cold and heat stress treatments on the branching coral Acropora yongei, and found that green fluorescent protein (GFP) concentration and fluorescence decreased with declining coral health, prior to initiation of bleaching. Ultimately, cold-treated corals acclimated and GFP concentration and fluorescence recovered. In contrast, heat-treated corals eventually bleached but showed strong fluorescence despite reduced GFP concentration, likely resulting from the large reduction in shading from decreased dinoflagellate density. Consequently, GFP concentration and fluorescence showed distinct correlations in non-bleached and bleached corals. Green fluorescence was positively correlated with dinoflagellate photobiology, but its closest correlation was with coral growth suggesting that green fluorescence could be used as a physiological proxy for health in some corals.

  5. Abstracts

    ERIC Educational Resources Information Center

    American Biology Teacher, 1977

    1977-01-01

    Included are over 50 abstracts of papers being presented at the 1977 National Association of Biology Teachers Convention. Included in each abstract are the title, author, and summary of the paper. Topics include photographic techniques environmental studies, and biological instruction. (MA)

  6. Ecology: Deep and complex ways to survive bleaching

    NASA Astrophysics Data System (ADS)

    Pandolfi, John M.

    2015-02-01

    Mass coral bleaching events can drive reefs from being the domains of corals to becoming dominated by seaweed. But longitudinal data show that more than half of the reefs studied rebound to their former glory. See Letter p.94

  7. "Choice" and destiny: the substrate composition and mechanical stability of settlement structures can mediate coral recruit fate in post-bleached reefs

    NASA Astrophysics Data System (ADS)

    Yadav, Shreya; Rathod, Pooja; Alcoverro, Teresa; Arthur, Rohan

    2016-03-01

    Increasingly frequent and intense ocean warming events seriously test the buffer and recovery capacities of tropical coral reefs. Post-disturbance, available settlement structures on a reef (often dead coral skeletons) vary considerably in their mechanical stability and substrate composition, critically influencing coral recruit settlement choice and fate. In the wake of a coral mass mortality in the Lakshadweep archipelago, we examine (1) the relative availability of recruit settlement structures (from stable to unstable: reef platform, dead massive coral, consolidated rubble, dead corymbose coral, dead tabular coral, and unconsolidated rubble) in 12 recovering reefs across three atolls in the archipelago, (2) the substrate composition [crustose coralline algae (CCA), mixed turf, macroalgae] of these structural forms, and (3) whether the choice and fate of young coral are mediated by the substrate and stability of different structural forms. For this, we measured the abundance and distribution of recruit (<1 cm), juvenile (1-5 cm), and young adult (5-10) corals of 24 common coral genera. Four years after the mass mortality, reefs differed considerably in composition of settlement structures. The structures themselves varied significantly in substrate cover with dead tables largely covered in CCA [60 ± 6.05 % (SE)] and dead corymbose coral dominated by mixed turf (61.83 ± 3.8 %). The youngest visible recruits (<1 cm) clearly preferred CCA-rich structures such as dead massives and tables. However, older size classes were rarely found on unstable structures (strongly "avoiding" tables, Ivlev's electivity index, E = -0.5). Our results indicate that while substrate cover might mediate coral choice, the mechanical stability of settlement structures is critical in determining post-settlement coral survival. The composition and availability of settlement structures on a reef may serve as a characteristic signature of its recovery potential, aiding in assessments of reef

  8. Large-amplitude internal waves benefit corals during thermal stress.

    PubMed

    Wall, M; Putchim, L; Schmidt, G M; Jantzen, C; Khokiattiwong, S; Richter, C

    2015-01-22

    Tropical scleractinian corals are particularly vulnerable to global warming as elevated sea surface temperatures (SSTs) disrupt the delicate balance between the coral host and their algal endosymbionts, leading to symbiont expulsion, mass bleaching and mortality. While satellite sensing of SST has proved a reliable predictor of coral bleaching at the regional scale, there are large deviations in bleaching severity and mortality on the local scale that are poorly understood. Here, we show that internal waves play a major role in explaining local coral bleaching and mortality patterns in the Andaman Sea. Despite a severe region-wide SST anomaly in May 2010, frequent upslope intrusions of cold sub-pycnocline waters due to breaking large-amplitude internal waves (LAIW) mitigated coral bleaching and mortality in shallow waters. In LAIW-sheltered waters, by contrast, bleaching-susceptible species suffered severe bleaching and total mortality. These findings suggest that LAIW benefit coral reefs during thermal stress and provide local refugia for bleaching-susceptible corals. LAIW are ubiquitous in tropical stratified waters and their swash zones may thus be important conservation areas for the maintenance of coral diversity in a warming climate. Taking LAIW into account can significantly improve coral bleaching predictions and provide a valuable tool for coral reef conservation and management.

  9. Large-amplitude internal waves benefit corals during thermal stress

    PubMed Central

    Wall, M.; Putchim, L.; Schmidt, G. M.; Jantzen, C.; Khokiattiwong, S.; Richter, C.

    2015-01-01

    Tropical scleractinian corals are particularly vulnerable to global warming as elevated sea surface temperatures (SSTs) disrupt the delicate balance between the coral host and their algal endosymbionts, leading to symbiont expulsion, mass bleaching and mortality. While satellite sensing of SST has proved a reliable predictor of coral bleaching at the regional scale, there are large deviations in bleaching severity and mortality on the local scale that are poorly understood. Here, we show that internal waves play a major role in explaining local coral bleaching and mortality patterns in the Andaman Sea. Despite a severe region-wide SST anomaly in May 2010, frequent upslope intrusions of cold sub-pycnocline waters due to breaking large-amplitude internal waves (LAIW) mitigated coral bleaching and mortality in shallow waters. In LAIW-sheltered waters, by contrast, bleaching-susceptible species suffered severe bleaching and total mortality. These findings suggest that LAIW benefit coral reefs during thermal stress and provide local refugia for bleaching-susceptible corals. LAIW are ubiquitous in tropical stratified waters and their swash zones may thus be important conservation areas for the maintenance of coral diversity in a warming climate. Taking LAIW into account can significantly improve coral bleaching predictions and provide a valuable tool for coral reef conservation and management. PMID:25473004

  10. The differential effects of increasing frequency and magnitude of extreme events on coral populations.

    PubMed

    Fabina, Nicholas S; Baskett, Marissa L; Gross, Kevin

    2015-09-01

    Extreme events, which have profound ecological consequences, are changing in both frequency and magnitude with climate change. Because extreme temperatures induce coral bleaching, we can explore the relative impacts of changes in frequency and magnitude of high temperature events on coral reefs. Here, we combined climate projections and a dynamic population model to determine how changing bleaching regimes influence coral persistence. We additionally explored how coral traits and competition with macroalgae mediate changes in bleaching regimes. Our results predict that severe bleaching events reduce coral persistence more than frequent bleaching. Corals with low adult mortality and high growth rates are successful when bleaching is mild, but bleaching resistance is necessary to persist when bleaching is severe, regardless of frequency. The existence of macroalgae-dominated stable states reduces coral persistence and changes the relative importance of coral traits. Building on previous studies, our results predict that management efforts may need to prioritize protection of "weaker" corals with high adult mortality when bleaching is mild, and protection of "stronger" corals with high bleaching resistance when bleaching is severe. In summary, future reef projections and conservation targets depend on both local bleaching regimes and biodiversity.

  11. Detrimental effects of host anemone bleaching on anemonefish populations

    NASA Astrophysics Data System (ADS)

    Saenz-Agudelo, P.; Jones, G. P.; Thorrold, S. R.; Planes, S.

    2011-06-01

    Coral bleaching and related reef degradation have caused significant declines in the abundance of reef-associated fishes. Most attention on the effects of bleaching has focused on corals, but bleaching is also prevalent in other cnidarians, including sea anemones. The consequences of anemone bleaching are unknown, and the demographic effects of bleaching on associated fish recruitment, survival, and reproduction are poorly understood. We examined the effect of habitat degradation including host anemone bleaching on fish abundance, egg production, and recruitment of the panda anemonefish ( Amphiprion polymnus) near Port Moresby, Papua New Guinea. Following a high-temperature anomaly in shallow waters of the region, most shallow anemones to a depth of 6 m (approximately 35% of all the anemones in this area) were severely bleached. Anemone mortality was low but bleached anemones underwent a ~34% reduction in body size. Total numbers of A. polymnus were not affected by bleaching and reduction in shelter area. While egg production of females living in bleached anemones was reduced by ~38% in 2009 compared to 2008, egg production of females on unbleached anemones did not differ significantly between years. Total recruitment in 2009 was much lower than in 2008. However, we found no evidence of recruiting larvae avoiding bleached anemones at settlement suggesting that other factors or different chemical cues were more important in determining recruitment than habitat quality. These results provide the first field evidence of detrimental effects of climate-induced bleaching and habitat degradation on reproduction and recruitment of anemonefish.

  12. Dietary shift in corallivorous Drupella snails following a major bleaching event at Koh Tao, Gulf of Thailand

    NASA Astrophysics Data System (ADS)

    Hoeksema, B. W.; Scott, C.; True, J. D.

    2013-06-01

    The island Koh Tao in the western Gulf of Thailand suffered severe coral bleaching in 2010. Its mushroom coral fauna of 20 species was surveyed during the bleaching in 2010 and after the bleaching in 2011. Multi-species assemblages of free-living mushroom corals occurred around the island, two of which were invaded by corallivorous Drupella snails after the bleaching. Previously these gastropods were known to mainly consume branching corals and hardly any mushroom corals. The snails were found preying on four fungiid species, three of which were susceptible to bleaching. The dietary shift became apparent after populations of preferred prey species (Acroporidae and Pocilloporidae) had died during the bleaching event. It seems that bleaching mortality reduced the availability of preferred prey, causing the corallivores to switch to less preferred species that occur in dense aggregations.

  13. Life histories predict coral community disassembly under multiple stressors.

    PubMed

    Darling, Emily S; McClanahan, Timothy R; Côté, Isabelle M

    2013-06-01

    Climate change is reshaping biological communities against a background of existing human pressure. Evaluating the impacts of multiple stressors on community dynamics can be particularly challenging in species-rich ecosystems, such as coral reefs. Here, we investigate whether life-history strategies and cotolerance to different stressors can predict community responses to fishing and temperature-driven bleaching using a 20-year time series of coral assemblages in Kenya. We found that the initial life-history composition of coral taxa largely determined the impacts of bleaching and coral loss. Prior to the 1998 bleaching event, coral assemblages within no-take marine reserves were composed of three distinct life histories - competitive, stress-tolerant and weedy- and exhibited strong declines following bleaching with limited subsequent recovery. In contrast, fished reefs had lower coral cover, fewer genera and were composed of stress-tolerant and weedy corals that were less affected by bleaching over the long term. Despite these general patterns, we found limited evidence for cotolerance as coral genera and life histories were variable in their sensitivities to fishing and bleaching. Overall, fishing and bleaching have reduced coral diversity and led to altered coral communities of 'survivor' species with stress-tolerant and weedy life histories. Our findings are consistent with expectations that climate change interacting with existing human pressure will result in the loss of coral diversity and critical reef habitat.

  14. Heterotrophy in tropical scleractinian corals.

    PubMed

    Houlbrèque, Fanny; Ferrier-Pagès, Christine

    2009-02-01

    The dual character of corals, that they are both auto- and heterotrophs, was recognized early in the twentieth Century. It is generally accepted that the symbiotic association between corals and their endosymbiotic algae (called zooxanthellae) is fundamental to the development of coral reefs in oligotrophic tropical oceans because zooxanthellae transfer the major part of their photosynthates to the coral host (autotrophic nutrition). However, numerous studies have confirmed that many species of corals are also active heterotrophs, ingesting organisms ranging from bacteria to mesozooplankton. Heterotrophy accounts for between 0 and 66% of the fixed carbon incorporated into coral skeletons and can meet from 15 to 35% of daily metabolic requirements in healthy corals and up to 100% in bleached corals. Apart from this carbon input, feeding is likely to be important to most scleractinian corals, since nitrogen, phosphorus, and other nutrients that cannot be supplied from photosynthesis by the coral's symbiotic algae must come from zooplankton capture, particulate matter or dissolved compounds. A recent study showed that during bleaching events some coral species, by increasing their feeding rates, are able to maintain and restore energy reserves. This review assesses the importance and effects of heterotrophy in tropical scleractinian corals. We first provide background information on the different food sources (from dissolved organic matter to meso- and macrozooplankton). We then consider the nutritional inputs of feeding. Finally, we review feeding effects on the different physiological parameters of corals (tissue composition, photosynthesis and skeletal growth).

  15. Assessing the Effects of Disease and Bleaching on Florida ...

    EPA Pesticide Factsheets

    Coral diseases have increased in frequency over the past few decades and have important influences on the structure and composition of coral reef communities. However, there is limited information on the etiologies of many coral diseases, and pathways via which coral diseases are acquired and transmitted are still in question. Furthermore, it is difficult to assess the impacts of disease on coral populations because outbreaks often co-occur with temperature-induced bleaching and anthropogenic stressors. We developed spatially-explicit population models of coral disease and bleaching dynamics to quantify the impact of six common diseases on Florida Keys corals, including aspergillosis, dark spots, white band, white plague, white patch, and yellow band. Models were fit to an 8-year data set of coral abundance, disease prevalence, and bleaching prevalence. Model selection was used to assess alternative pathways for disease transmission, and the influence of environmental stressors, including sea temperature and human population density, on disease prevalence and coral mortality. Classic disease transmission from contagious to susceptible colonies provided the best model only for aspergillosis. For other diseases, direct transmission from the external environment provided the best fit to observed data. Estimates of disease reproductive ratio values (R0) were less than one for each disease, indicating coral colonies were below densities required for diseases

  16. Taxonomic, Spatial and Temporal Patterns of Bleaching in Anemones Inhabited by Anemonefishes

    PubMed Central

    Hobbs, Jean-Paul A.; Frisch, Ashley J.; Ford, Benjamin M.; Thums, Michele; Saenz-Agudelo, Pablo; Furby, Kathryn A.; Berumen, Michael L.

    2013-01-01

    Background Rising sea temperatures are causing significant destruction to coral reef ecosystems due to coral mortality from thermally-induced bleaching (loss of symbiotic algae and/or their photosynthetic pigments). Although bleaching has been intensively studied in corals, little is known about the causes and consequences of bleaching in other tropical symbiotic organisms. Methodology/Principal Findings This study used underwater visual surveys to investigate bleaching in the 10 species of anemones that host anemonefishes. Bleaching was confirmed in seven anemone species (with anecdotal reports of bleaching in the other three species) at 10 of 19 survey locations spanning the Indo-Pacific and Red Sea, indicating that anemone bleaching is taxonomically and geographically widespread. In total, bleaching was observed in 490 of the 13,896 surveyed anemones (3.5%); however, this percentage was much higher (19–100%) during five major bleaching events that were associated with periods of elevated water temperatures and coral bleaching. There was considerable spatial variation in anemone bleaching during most of these events, suggesting that certain sites and deeper waters might act as refuges. Susceptibility to bleaching varied between species, and in some species, bleaching caused reductions in size and abundance. Conclusions/Significance Anemones are long-lived with low natural mortality, which makes them particularly vulnerable to predicted increases in severity and frequency of bleaching events. Population viability will be severely compromised if anemones and their symbionts cannot acclimate or adapt to rising sea temperatures. Anemone bleaching also has negative effects to other species, particularly those that have an obligate relationship with anemones. These effects include reductions in abundance and reproductive output of anemonefishes. Therefore, the future of these iconic and commercially valuable coral reef fishes is inextricably linked to the ability of

  17. Behaviourally mediated phenotypic selection in a disturbed coral reef environment.

    PubMed

    McCormick, Mark I

    2009-09-18

    Natural and anthropogenic disturbances are leading to changes in the nature of many habitats globally, and the magnitude and frequency of these perturbations are predicted to increase under climate change. Globally coral reefs are one of the most vulnerable ecosystems to climate change. Fishes often show relatively rapid declines in abundance when corals become stressed and die, but the processes responsible are largely unknown. This study explored the mechanism by which coral bleaching may influence the levels and selective nature of mortality on a juvenile damselfish, Pomacentrus amboinensis, which associates with hard coral. Recently settled fish had a low propensity to migrate small distances (40 cm) between habitat patches, even when densities were elevated to their natural maximum. Intraspecific interactions and space use differ among three habitats: live hard coral, bleached coral and dead algal-covered coral. Large fish pushed smaller fish further from the shelter of bleached and dead coral thereby exposing smaller fish to higher mortality than experienced on healthy coral. Small recruits suffered higher mortality than large recruits on bleached and dead coral. Mortality was not size selective on live coral. Survival was 3 times as high on live coral as on either bleached or dead coral. Subtle behavioural interactions between fish and their habitats influence the fundamental link between life history stages, the distribution of phenotypic traits in the local population and potentially the evolution of life history strategies.

  18. The effect of prolonged ``bleaching'' on skeletal banding and stable isotopic composition in Montastrea annularis

    NASA Astrophysics Data System (ADS)

    Leder, James J.; Szmant, Alina M.; Swart, Peter K.

    1991-07-01

    X-radiography and carbon and oxygen stable isotope analysis have been used to examine the effects of prolonged “bleaching” on the growth rate and chemical composition of the skeleton of the massive reef coral, Montastrea annularis. The post-bleaching linear growth of one colony that remained bleached for 10 to 12 months following the 1987 Caribbean-wide bleaching event was only 37% of mean annual growth from pre-bleaching years, and was manifest as a loss of the following year's low density band. Two colonies that did not bleach (normal) and two that bleached and regained their coloration (recovered) had linear growth rates over the same period that were 81 to 98% of mean pre-bleaching annual growth. Linear growth by a third recovered coral was 66% of pre-bleaching growth. No sub-annual stress bands were associated with the bleaching. The skeleton of the bleached colony had carbon and oxygen isotopic compositions that were reduced in range and enriched (increased) in both 13C and 18O in the post-bleaching year. The skeletons of two of the nine colonies, one bleached and one recovered, had depleted (reduced) δ18O values (-5.3 and -4.8%., respectively) during the bleaching episode that agree with the suggestion that positive temperature anomalies occurred during, and may have caused, the bleaching event. The range and values for all other normal and recovered corals, however, were not different between the post-bleaching year and previous years. Our data suggest that stress bands and isotopic analysis of coral skeletons may not always be reliable tools for examining the occurrence, cause or effects of certain discrete stress events that may interrupt skeletal growth.

  19. Does seaweed-coral competition make seaweeds more palatable?

    NASA Astrophysics Data System (ADS)

    Longo, G. O.; Hay, M. E.

    2015-03-01

    Seaweed-coral interactions are increasingly common on modern coral reefs, but the dynamics, processes, and mechanisms affecting these interactions are inadequately understood. We investigated the frequency and effect of seaweed-coral contacts for common seaweeds and corals in Belize. Effects on corals were evaluated by measuring the frequency and extent of bleaching when contacted by various seaweeds, and effects on a common seaweed were evaluated by assessing whether contact with coral made the seaweed more palatable to the sea urchin Diadema antillarum. Coral-seaweed contacts were particularly frequent between Agaricia corals and the seaweed Halimeda opuntia, with this interaction being associated with coral bleaching in 95 % of contacts. Pooling across all coral species, H. opuntia was the seaweed most commonly contacting corals and most frequently associated with localized bleaching at the point of contact. Articulated coralline algae, Halimeda tuna and Lobophora variegata also frequently contacted corals and were commonly associated with bleaching. The common corals Agaricia and Porites bleached with similar frequency when contacted by H. opuntia (95 and 90 %, respectively), but Agaricia experienced more damage than Porites when contacted by articulated coralline algae or H. tuna. When spatially paired individuals of H. opuntia that had been in contact with Agaricia and not in contact with any coral were collected from the reefs and offered to D. antillarum, urchins consumed about 150 % more of thalli that had been competing with Agaricia. Contact and non-contact thalli did not differ in nutritional traits (ash-free-dry-mass, C or N concentrations), suggesting that Halimeda chemical defenses may have been compromised by coral-algal contact. If competition with corals commonly enhances seaweed palatability, then the dynamics and nuances of small-scale seaweed-coral-herbivore interactions at coral edges are deserving of greater attention in that such

  20. The Assimilation of Diazotroph-Derived Nitrogen by Scleractinian Corals Depends on Their Metabolic Status

    PubMed Central

    Grover, Renaud; Maguer, Jean-François; Fine, Maoz; Ferrier-Pagès, Christine

    2017-01-01

    ABSTRACT Tropical corals are associated with a diverse community of dinitrogen (N2)-fixing prokaryotes (diazotrophs) providing the coral an additional source of bioavailable nitrogen (N) in oligotrophic waters. The overall activity of these diazotrophs changes depending on the current environmental conditions, but to what extent it affects the assimilation of diazotroph-derived N (DDN) by corals is still unknown. Here, in a series of 15N2 tracer experiments, we directly quantified DDN assimilation by scleractinian corals from the Red Sea exposed to different environmental conditions. We show that DDN assimilation strongly varied with the corals’ metabolic status or with phosphate availability in the water. The very autotrophic shallow-water (~5 m) corals showed low or no DDN assimilation, which significantly increased under elevated phosphate availability (3 µM). Corals that depended more on heterotrophy (i.e., bleached and deep-water [~45 m] corals) assimilated significantly more DDN, which contributed up to 15% of the corals’ N demand (compared to 1% in shallow corals). Furthermore, we demonstrate that a substantial part of the DDN assimilated by deep corals was likely obtained from heterotrophic feeding on fixed N compounds and/or diazotrophic cells in the mucus. Conversely, in shallow corals, the net release of mucus, rich in organic carbon compounds, likely enhanced diazotroph abundance and activity and thereby the release of fixed N to the pelagic and benthic reef community. Overall, our results suggest that DDN assimilation by corals varies according to the environmental conditions and is likely linked to the capacity of the coral to acquire nutrients from seawater. PMID:28074021

  1. Excess seawater nutrients, enlarged algal symbiont densities and bleaching sensitive reef locations: 2. A regional-scale predictive model for the Great Barrier Reef, Australia.

    PubMed

    Wooldridge, Scott A; Heron, Scott F; Brodie, Jon E; Done, Terence J; Masiri, Itsara; Hinrichs, Saskia

    2017-01-15

    A spatial risk assessment model is developed for the Great Barrier Reef (GBR, Australia) that helps identify reef locations at higher or lower risk of coral bleaching in summer heat-wave conditions. The model confirms the considerable benefit of discriminating nutrient-enriched areas that contain corals with enlarged (suboptimal) symbiont densities for the purpose of identifying bleaching-sensitive reef locations. The benefit of the new system-level understanding is showcased in terms of: (i) improving early-warning forecasts of summer bleaching risk, (ii) explaining historical bleaching patterns, (iii) testing the bleaching-resistant quality of the current marine protected area (MPA) network (iv) identifying routinely monitored coral health attributes, such as the tissue energy reserves and skeletal growth characteristics (viz. density and extension rates) that correlate with bleaching resistant reef locations, and (v) targeting region-specific water quality improvement strategies that may increase reef-scale coral health and bleaching resistance.

  2. Spectral response of the coral rubble, living corals, and dead corals: study case on the Spermonde Archipelago, Indonesia

    NASA Astrophysics Data System (ADS)

    Nurdin, Nurjannah; Komatsu, Teruhisa; Yamano, Hiroya; Arafat, Gulam; Rani, Chair; Akbar AS, M.

    2012-10-01

    Coral reefs play important ecological services such as providing foods, biodiversity, nutrient recycling etc. for human society. On the other hand, they are threatened by human impacts such as illegal fishing and environmental changes such as rises of sea water temperature and sea level due to global warming. Thus, it is very important to monitor dynamic spatial distributions of coral reefs and related habitats such as coral rubble, dead coral, bleached corals, seagrass, etc. Hyperspectral data, in particular, offer high potential for characterizing and mapping coral reefs because of their capability to identify individual reef components based on their detailed spectral response. We studied the optical properties by measuring in situ spectra of living corals, dead coral and coral rubble covered with algae. Study site was selected in Spermonde archipelago, South Sulawesi, Indonesia because this area is included in the highest diversity of corals in the world named as Coral Triangle, which is recognized as the global centre of marine biodiversity and a global priority for conservation. Correlation analysis and cluster analysis support that there are distinct differences in reflectance spectra among categories. Common spectral characteristic of living corals, dead corals and coral rubble covered with algae was a reflectance minimum at 674 nm. Healthy corals, dead coral covered with algae and coral rubble covered with algae showed high similarity of spectral reflectance. It is estimated that this is due to photsynthetic pigments.

  3. Molecular toxicology of corals: a review.

    PubMed

    Rotchell, Jeanette M; Ostrander, Gary K

    2011-01-01

    Coral reefs worldwide have become increasingly affected by a phenomenon known as "coral bleaching," the loss of the symbiotic algae from the host corals. The underlying causes and mechanism(s) of coral bleaching are not well known, although several have been hypothesized. While coral bleaching has been a primary focus in recent years, corals respond differentially to numerous environmental stresses. The impacts of heat, hydrocarbons, salinity, sewage effluents, biocides, heavy metals, and ultraviolet light have been investigated in both laboratory experiments and field surveys among multiple coral species. Herein what is known regarding the biological impacts of such stresses on corals at the molecular level of organization is summarized. The objective is to focus attention at the early stages of biological effects in order to encourage and facilitate research that provide ways to understand how changes at the molecular level might elucidate processes likely occurring at the population level. This, in turn, should accelerate studies that may elucidate the cellular and physiological changes contributing to coral decline, rather than just document the continued global loss of coral diversity and abundance.

  4. CORAL REEF RESPONSES TO GLOBAL CLIMATE CHANGE

    EPA Science Inventory

    Increased emissions of greenhouse gases and synthetic compounds are related to rising sea temperatures and increased penetration of ultraviolet radiation (UVR), two factors that are consistently linked to bleaching and disease of corals. Coral reefs play a major role in the envir...

  5. NOAA Coral Reef Watch: Decision Support Tools for Coral Reef Managers

    NASA Astrophysics Data System (ADS)

    Rauenzahn, J.; Eakin, C.; Skirving, W. J.; Burgess, T.; Christensen, T.; Heron, S. F.; Li, J.; Liu, G.; Morgan, J.; Nim, C.; Parker, B. A.; Strong, A. E.

    2010-12-01

    A multitude of natural and anthropogenic stressors exert substantial influence on coral reef ecosystems and contribute to bleaching events, slower coral growth, infectious disease outbreaks, and mortality. Satellite-based observations can monitor, at a global scale, environmental conditions that influence both short-term and long-term coral reef ecosystem health. From research to operations, NOAA Coral Reef Watch (CRW) incorporates paleoclimatic, in situ, and satellite-based biogeophysical data to provide near-real-time and forecast information and tools to help managers, researchers, and other stakeholders interpret coral health and stress. CRW has developed an operational, near-real-time product suite that includes sea surface temperature (SST), SST time series data, SST anomaly charts, coral bleaching HotSpots, and Degree Heating Weeks (DHW). Bi-weekly global SST analyses are based on operational nighttime-only SST at 50-km resolution. CRW is working to develop high-resolution products to better address thermal stress on finer scales and is applying climate models to develop seasonal outlooks of coral bleaching. Automated Satellite Bleaching Alerts (SBAs), available at Virtual Stations worldwide, provide the only global early-warning system to notify managers of changing reef environmental conditions. Currently, CRW is collaborating with numerous domestic and international partners to develop new tools to address ocean acidification, infectious diseases of corals, combining light and temperature to detect coral photosystem stress, and other parameters.

  6. A coral-on-a-chip microfluidic platform enabling live-imaging microscopy of reef-building corals.

    PubMed

    Shapiro, Orr H; Kramarsky-Winter, Esti; Gavish, Assaf R; Stocker, Roman; Vardi, Assaf

    2016-03-04

    Coral reefs, and the unique ecosystems they support, are facing severe threats by human activities and climate change. Our understanding of these threats is hampered by the lack of robust approaches for studying the micro-scale interactions between corals and their environment. Here we present an experimental platform, coral-on-a-chip, combining micropropagation and microfluidics to allow direct microscopic study of live coral polyps. The small and transparent coral micropropagates are ideally suited for live-imaging microscopy, while the microfluidic platform facilitates long-term visualization under controlled environmental conditions. We demonstrate the usefulness of this approach by imaging coral micropropagates at previously unattainable spatio-temporal resolutions, providing new insights into several micro-scale processes including coral calcification, coral-pathogen interaction and the loss of algal symbionts (coral bleaching). Coral-on-a-chip thus provides a powerful method for studying coral physiology in vivo at the micro-scale, opening new vistas in coral biology.

  7. Chemically rich seaweeds poison corals when not controlled by herbivores.

    PubMed

    Rasher, Douglas B; Hay, Mark E

    2010-05-25

    Coral reefs are in dramatic global decline, with seaweeds commonly replacing corals. It is unclear, however, whether seaweeds harm corals directly or colonize opportunistically following their decline and then suppress coral recruitment. In the Caribbean and tropical Pacific, we show that, when protected from herbivores, approximately 40 to 70% of common seaweeds cause bleaching and death of coral tissue when in direct contact. For seaweeds that harmed coral tissues, their lipid-soluble extracts also produced rapid bleaching. Coral bleaching and mortality was limited to areas of direct contact with seaweeds or their extracts. These patterns suggest that allelopathic seaweed-coral interactions can be important on reefs lacking herbivore control of seaweeds, and that these interactions involve lipid-soluble metabolites transferred via direct contact. Seaweeds were rapidly consumed when placed on a Pacific reef protected from fishing but were left intact or consumed at slower rates on an adjacent fished reef, indicating that herbivory will suppress seaweeds and lower frequency of allelopathic damage to corals if reefs retain intact food webs. With continued removal of herbivores from coral reefs, seaweeds are becoming more common. This occurrence will lead to increasing frequency of seaweed-coral contacts, increasing allelopathic suppression of remaining corals, and continuing decline of reef corals.

  8. Heterotrophic compensation: a possible mechanism for resilience of coral reefs to global warming or a sign of prolonged stress?

    PubMed

    Hughes, Adam D; Grottoli, Andréa G

    2013-01-01

    Thermally induced bleaching has caused a global decline in corals and the frequency of such bleaching events will increase. Thermal bleaching severely disrupts the trophic behaviour of the coral holobiont, reducing the photosynthetically derived energy available to the coral host. In the short term this reduction in energy transfer from endosymbiotic algae results in an energy deficit for the coral host. If the bleaching event is short-lived then the coral may survive this energy deficit by depleting its lipid reserves, or by increasing heterotrophic energy acquisition. We show for the first time that the coral animal is capable of increasing the amount of heterotrophic carbon incorporated into its tissues for almost a year following bleaching. This prolonged heterotrophic compensation could be a sign of resilience or prolonged stress. If the heterotrophic compensation is in fact an acclimatization response, then this physiological response could act as a buffer from future bleaching by providing sufficient heterotrophic energy to compensate for photoautotrophic energy losses during bleaching, and potentially minimizing the effect of subsequent elevated temperature stresses. However, if the elevated incorporation of zooplankton is a sign that the effects of bleaching continue to be stressful on the holobiont, even after 11 months of recovery, then this physiological response would indicate that complete coral recovery requires more than 11 months to achieve. If coral bleaching becomes an annual global phenomenon by mid-century, then present temporal refugia will not be sufficient to allow coral colonies to recover between bleaching events and coral reefs will become increasingly less resilient to future climate change. If, however, increasing their sequestration of zooplankton-derived nutrition into their tissues over prolonged periods of time is a compensating mechanism, the impacts of annual bleaching may be reduced. Thus, some coral species may be better

  9. Large-amplitude internal waves sustain coral health during thermal stress

    NASA Astrophysics Data System (ADS)

    Schmidt, Gertraud M.; Wall, Marlene; Taylor, Marc; Jantzen, Carin; Richter, Claudio

    2016-09-01

    Ocean warming is a major threat for coral reefs causing widespread coral bleaching and mortality. Potential refugia are thus crucial for coral survival. Exposure to large-amplitude internal waves (LAIW) mitigated heat stress and ensured coral survival and recovery during and after an extreme heat anomaly. The physiological status of two common corals, Porites lutea and Pocillopora meandrina, was monitored in host and symbiont traits, in response to LAIW-exposure throughout the unprecedented 2010 heat anomaly in the Andaman Sea. LAIW-exposed corals of both species survived and recovered, while LAIW-sheltered corals suffered partial and total mortality in P. lutea and P. meandrina, respectively. LAIW are ubiquitous in the tropics and potentially generate coral refuge areas. As thermal stress to corals is expected to increase in a warming ocean, the mechanisms linking coral bleaching to ocean dynamics will be crucial to predict coral survival on a warming planet.

  10. Methods to Estimate Solar Radiation Dosimetry in Coral Reefs Using Remote Sensed, Modeled, and in Situ Data.

    EPA Science Inventory

    Solar irradiance has been increasingly recognized as an important determinant of bleaching in coral reefs, but measurements of solar radiation exposure within coral reefs have been relatively limited. Solar irradiance and diffuse down welling attenuation coefficients (Kd, m-1) we...

  11. SIMULATED SOLAR ULTRAVIOLET RADIATION EFFECTS ON 5 SPECIES OF SCLERACTINIAN CORALS

    EPA Science Inventory

    The impact of global climate change factors such as increased temperature and ultraviolet radiation (UVR) on coral bleaching are of continued interest to the USEPA. Coral bleaching occurs when symbiotic zooxanthellae and/or their pigments are depleted in response to stressors suc...

  12. Population dynamics of zooxanthellae during a bacterial bleaching event

    NASA Astrophysics Data System (ADS)

    Shenkar, N.; Fine, M.; Kramarsky-Winter, E.; Loya, Y.

    2006-05-01

    Each summer 80-90% of the colonies of Oculina patagonica undergo bleaching off the Mediterranean coast of Israel. To investigate fluctuations through a yearly bleaching cycle, monthly measurements of zooxanthella density, mitotic index and chlorophyll- a concentration were conducted. Results showed (1) a significant negative correlation between sea surface temperature (SST) and zooxanthella density; (2) both significantly lower zooxanthella mitotic index and higher chlorophyll -a per zooxanthella content during the bleaching season compared with the non-bleaching period; (3) prior to bleaching, a lag between the peak of zooxanthella density and chlorophyll- a concentration followed by a similar lag during recovery. Zooxanthella density declined significantly between March and May while chlorophyll- a concentration peaked in April, and then declined. Zooxanthella density increased significantly in November while chlorophyll- a concentration increased significantly in January. We conclude that during bacterial bleaching events, zooxanthellae are severely damaged. However, by the time of the following bleaching event the coral tissues regain their “normal” (pre-bleaching) zooxanthella population density.

  13. Unprecedented Disease-Related Coral Mortality in Southeastern Florida

    PubMed Central

    Precht, William F.; Gintert, Brooke E.; Robbart, Martha L.; Fura, Ryan; van Woesik, Robert

    2016-01-01

    Anomalously high water temperatures, associated with climate change, are increasing the global prevalence of coral bleaching, coral diseases, and coral-mortality events. Coral bleaching and disease outbreaks are often inter-related phenomena, since many coral diseases are a consequence of opportunistic pathogens that further compromise thermally stressed colonies. Yet, most coral diseases have low prevalence (<5%), and are not considered contagious. By contrast, we document the impact of an extremely high-prevalence outbreak (61%) of white-plague disease at 14 sites off southeastern Florida. White-plague disease was observed near Virginia Key, Florida, in September 2014, and after 12 months had spread 100 km north and 30 km south. The disease outbreak directly followed a high temperature coral-bleaching event and affected at least 13 coral species. Eusmilia fastigiata, Meandrina meandrites, and Dichocoenia stokesi were the most heavily impacted coral species, and were reduced to <3% of their initial population densities. A number of other coral species, including Colpophyllia natans, Pseudodiploria strigosa, Diploria labyrinthiformis, and Orbicella annularis were reduced to <25% of their initial densities. The high prevalence of disease, the number of susceptible species, and the high mortality of corals affected suggests this disease outbreak is arguably one of the most lethal ever recorded on a contemporary coral reef. PMID:27506875

  14. Unprecedented Disease-Related Coral Mortality in Southeastern Florida

    NASA Astrophysics Data System (ADS)

    Precht, William F.; Gintert, Brooke E.; Robbart, Martha L.; Fura, Ryan; van Woesik, Robert

    2016-08-01

    Anomalously high water temperatures, associated with climate change, are increasing the global prevalence of coral bleaching, coral diseases, and coral-mortality events. Coral bleaching and disease outbreaks are often inter-related phenomena, since many coral diseases are a consequence of opportunistic pathogens that further compromise thermally stressed colonies. Yet, most coral diseases have low prevalence (<5%), and are not considered contagious. By contrast, we document the impact of an extremely high-prevalence outbreak (61%) of white-plague disease at 14 sites off southeastern Florida. White-plague disease was observed near Virginia Key, Florida, in September 2014, and after 12 months had spread 100 km north and 30 km south. The disease outbreak directly followed a high temperature coral-bleaching event and affected at least 13 coral species. Eusmilia fastigiata, Meandrina meandrites, and Dichocoenia stokesi were the most heavily impacted coral species, and were reduced to <3% of their initial population densities. A number of other coral species, including Colpophyllia natans, Pseudodiploria strigosa, Diploria labyrinthiformis, and Orbicella annularis were reduced to <25% of their initial densities. The high prevalence of disease, the number of susceptible species, and the high mortality of corals affected suggests this disease outbreak is arguably one of the most lethal ever recorded on a contemporary coral reef.

  15. 1997-98: Unprecedented thermal stress to coral reefs?

    NASA Astrophysics Data System (ADS)

    Lough, J. M.

    2000-12-01

    Mass bleaching is a stress response of corals subjected to warmer-than-normal seawater temperatures during the warm season. During 1997-98 there were unprecedented numbers of reports of bleaching on many of the world's coral reefs. Observational evidence suggests an increase in frequency of mass coral bleaching events since the late 1970s. Two indices of warm season sea surface temperatures (SSTs; SST maximum anomaly and degree-months) are presented for 47 reef sites where bleaching occurred during 1997-98. The level of thermal stress at the vast majority of these coral reef sites during 1997-98 was unmatched in the period 1903-99. Warm season SSTs at these coral reef sites have significantly warmed over this period and the frequency of warm season SST extremes has increased since the late 1970s. Continued warming of tropical SSTs, as is likely due to the enhanced greenhouse effect, will increase the level of thermal stress to coral reefs. Increased frequency of bleaching events will reduce corals' capacity to recover and may significantly alter the make-up of present day coral reef ecosystems.

  16. REGIONAL MONITORING OF CORAL CONDITION IN THE FLORIDA KEYS

    EPA Science Inventory

    Tropical reef corals have experienced unprecedented levels of bleaching and disease during the last three decades. Declining health has been attributed to several stressors, including exposures to elevated water temperature, increased solar radiation, and degraded water quality. ...

  17. Formalising a mechanistic linkage between heterotrophic feeding and thermal bleaching resistance

    NASA Astrophysics Data System (ADS)

    Wooldridge, Scott A.

    2014-12-01

    In this paper, I utilise the CO2 (sink) limitation model of coral bleaching to propose a new biochemical framework that explains how certain (well-adapted) coral species can utilise heterotrophic carbon acquisition to combat the damaging algal photoinhibition response sequence that underpins thermal bleaching, thereby increasing thermal bleaching resistance. This mechanistic linkage helps to clarify a number of previously challenging experimental responses arising from feeding (versus starved) temperature stress experiments, and isotope labelling (tracer) experiments with heterotrophic carbon sources (e.g., zooplankton). In an era of rapidly warming surface ocean temperatures, the conferred fitness benefits arising from such a mechanistic linkage are considerable. Yet, various ecological constraints are outlined which caution against the ultimate benefit of the mechanism for raising bleaching thresholds at the coral community (reef) scale. Future experiments are suggested that can strengthen these proposed arguments.

  18. Food availability promotes rapid recovery from thermal stress in a scleractinian coral

    NASA Astrophysics Data System (ADS)

    Connolly, S. R.; Lopez-Yglesias, M. A.; Anthony, K. R. N.

    2012-12-01

    Bleaching in corals due to environmental stress represents a loss of energy intake often leading to an increase in mortality risk. Successful coral recovery from severe bleaching events may depend on the rate of replenishment of algal symbiont populations following the period of thermal stress, the supply of an alternative food source, or both. Here, we explore the role of food availability in promoting the survival and recovery of a common coral ( Acropora intermedia) following acute experimentally induced thermal stress. Fed corals were provided with live rotifers daily, to maintain densities of zooplankton in tanks that are typical of coral reefs. After a 6-week acclimation phase, heated corals were subjected to a +4 °C thermal anomaly for a 7-day period (bleaching phase) then temperatures were returned to normal for a further 2 weeks (recovery phase). Results demonstrated that heated corals had higher survival when they were provided with heterotrophic food. Fed corals experienced reduced loss of chlorophyll a, relative to unfed corals. During the recovery phase, both fed and unfed corals recovered within a few days; however, fed corals recovered to pre-bleaching phase levels of chlorophyll a, whereas unfed corals stabilized approximately one-third below this level. Protein levels of fed corals declined markedly during the bleaching phase, but recovered all of their losses by the end of the recovery phase. In contrast, unfed corals had low protein levels that were maintained throughout the experiment. To the extent that these results are representative of corals' responses to thermal anomalies in nature, the findings imply that availability of particulate food matter has the potential to increase corals' capacity to survive thermally induced bleaching and to ameliorate its sub-lethal effects. They also support the hypothesis that different rates of heterotrophy are an important determinant of variation in resilience to thermal stress among reef environments.

  19. Tenacious D: Symbiodinium in clade D remain in reef corals at both high and low temperature extremes despite impairment.

    PubMed

    Silverstein, Rachel N; Cunning, Ross; Baker, Andrew C

    2017-04-01

    Reef corals are sensitive to thermal stress, which induces coral bleaching (the loss of algal symbionts), often leading to coral mortality. However, corals hosting certain symbionts (notably some members of Symbiodinium clade D) resist bleaching when exposed to high temperatures. To determine whether these symbionts are also cold tolerant, we exposed corals hosting either Symbiodinium C3 or D1a to incremental warming (+1°C week(-1) to 35°C) and cooling (-1°C week(-1) to 15°C), and measured photodamage and symbiont loss. During warming to 33°C, C3 corals were photodamaged and lost >99% of symbionts, while D1a corals experienced photodamage but did not bleach. During cooling, D1a corals suffered more photodamage than C3 corals but still did not bleach, while C3 corals lost 94% of symbionts. These results indicate that photodamage does not always lead to bleaching, suggesting alternate mechanisms exist by which symbionts resist bleaching, and helping explain the persistence of D1a symbionts on recently bleached reefs, with implications for the future of these ecosystems.

  20. Local bleaching thresholds established by remote sensing techniques vary among reefs with deviating bleaching patterns during the 2012 event in the Arabian/Persian Gulf.

    PubMed

    Shuail, Dawood; Wiedenmann, Jörg; D'Angelo, Cecilia; Baird, Andrew H; Pratchett, Morgan S; Riegl, Bernhard; Burt, John A; Petrov, Peter; Amos, Carl

    2016-04-30

    A severe bleaching event affected coral communities off the coast of Abu Dhabi, UAE in August/September, 2012. In Saadiyat and Ras Ghanada reefs ~40% of the corals showed signs of bleaching. In contrast, only 15% of the corals were affected on Delma reef. Bleaching threshold temperatures for these sites were established using remotely sensed sea surface temperature (SST) data recorded by MODIS-Aqua. The calculated threshold temperatures varied between locations (34.48 °C, 34.55 °C, 35.05 °C), resulting in site-specific deviations in the numbers of days during which these thresholds were exceeded. Hence, the less severe bleaching of Delma reef might be explained by the lower relative heat stress experienced by this coral community. However, the dominance of Porites spp. that is associated with the long-term exposure of Delma reef to elevated temperatures, as well as the more pristine setting may have additionally contributed to the higher coral bleaching threshold for this site.

  1. Bacterial community dynamics are linked to patterns of coral heat tolerance.

    PubMed

    Ziegler, Maren; Seneca, Francois O; Yum, Lauren K; Palumbi, Stephen R; Voolstra, Christian R

    2017-02-10

    Ocean warming threatens corals and the coral reef ecosystem. Nevertheless, corals can be adapted to their thermal environment and inherit heat tolerance across generations. In addition, the diverse microbes that associate with corals have the capacity for more rapid change, potentially aiding the adaptation of long-lived corals. Here, we show that the microbiome of reef corals is different across thermally variable habitats and changes over time when corals are reciprocally transplanted. Exposing these corals to thermal bleaching conditions changes the microbiome for heat-sensitive corals, but not for heat-tolerant corals growing in habitats with natural high heat extremes. Importantly, particular bacterial taxa predict the coral host response in a short-term heat stress experiment. Such associations could result from parallel responses of the coral and the microbial community to living at high natural temperatures. A competing hypothesis is that the microbial community and coral heat tolerance are causally linked.

  2. Bacterial community dynamics are linked to patterns of coral heat tolerance

    PubMed Central

    Ziegler, Maren; Seneca, Francois O.; Yum, Lauren K.; Palumbi, Stephen R.; Voolstra, Christian R.

    2017-01-01

    Ocean warming threatens corals and the coral reef ecosystem. Nevertheless, corals can be adapted to their thermal environment and inherit heat tolerance across generations. In addition, the diverse microbes that associate with corals have the capacity for more rapid change, potentially aiding the adaptation of long-lived corals. Here, we show that the microbiome of reef corals is different across thermally variable habitats and changes over time when corals are reciprocally transplanted. Exposing these corals to thermal bleaching conditions changes the microbiome for heat-sensitive corals, but not for heat-tolerant corals growing in habitats with natural high heat extremes. Importantly, particular bacterial taxa predict the coral host response in a short-term heat stress experiment. Such associations could result from parallel responses of the coral and the microbial community to living at high natural temperatures. A competing hypothesis is that the microbial community and coral heat tolerance are causally linked. PMID:28186132

  3. Bacterial community dynamics are linked to patterns of coral heat tolerance

    NASA Astrophysics Data System (ADS)

    Ziegler, Maren; Seneca, Francois O.; Yum, Lauren K.; Palumbi, Stephen R.; Voolstra, Christian R.

    2017-02-01

    Ocean warming threatens corals and the coral reef ecosystem. Nevertheless, corals can be adapted to their thermal environment and inherit heat tolerance across generations. In addition, the diverse microbes that associate with corals have the capacity for more rapid change, potentially aiding the adaptation of long-lived corals. Here, we show that the microbiome of reef corals is different across thermally variable habitats and changes over time when corals are reciprocally transplanted. Exposing these corals to thermal bleaching conditions changes the microbiome for heat-sensitive corals, but not for heat-tolerant corals growing in habitats with natural high heat extremes. Importantly, particular bacterial taxa predict the coral host response in a short-term heat stress experiment. Such associations could result from parallel responses of the coral and the microbial community to living at high natural temperatures. A competing hypothesis is that the microbial community and coral heat tolerance are causally linked.

  4. Potential role of viruses in white plague coral disease.

    PubMed

    Soffer, Nitzan; Brandt, Marilyn E; Correa, Adrienne M S; Smith, Tyler B; Thurber, Rebecca Vega

    2014-02-01

    White plague (WP)-like diseases of tropical corals are implicated in reef decline worldwide, although their etiological cause is generally unknown. Studies thus far have focused on bacterial or eukaryotic pathogens as the source of these diseases; no studies have examined the role of viruses. Using a combination of transmission electron microscopy (TEM) and 454 pyrosequencing, we compared 24 viral metagenomes generated from Montastraea annularis corals showing signs of WP-like disease and/or bleaching, control conspecific corals, and adjacent seawater. TEM was used for visual inspection of diseased coral tissue. No bacteria were visually identified within diseased coral tissues, but viral particles and sequence similarities to eukaryotic circular Rep-encoding single-stranded DNA viruses and their associated satellites (SCSDVs) were abundant in WP diseased tissues. In contrast, sequence similarities to SCSDVs were not found in any healthy coral tissues, suggesting SCSDVs might have a role in WP disease. Furthermore, Herpesviridae gene signatures dominated healthy tissues, corroborating reports that herpes-like viruses infect all corals. Nucleocytoplasmic large DNA virus (NCLDV) sequences, similar to those recently identified in cultures of Symbiodinium (the algal symbionts of corals), were most common in bleached corals. This finding further implicates that these NCLDV viruses may have a role in bleaching, as suggested in previous studies. This study determined that a specific group of viruses is associated with diseased Caribbean corals and highlights the potential for viral disease in regional coral reef decline.

  5. Caribbean massive corals not recovering from repeated thermal stress events during 2005-2013.

    PubMed

    Neal, Benjamin Paul; Khen, Adi; Treibitz, Tali; Beijbom, Oscar; O'Connor, Grace; Coffroth, Mary Alice; Knowlton, Nancy; Kriegman, David; Mitchell, B Greg; Kline, David I

    2017-03-01

    Massive coral bleaching events associated with high sea surface temperatures are forecast to become more frequent and severe in the future due to climate change. Monitoring colony recovery from bleaching disturbances over multiyear time frames is important for improving predictions of future coral community changes. However, there are currently few multiyear studies describing long-term outcomes for coral colonies following acute bleaching events. We recorded colony pigmentation and size for bleached and unbleached groups of co-located conspecifics of three major reef-building scleractinian corals (Orbicella franksi, Siderastrea siderea, and Stephanocoenia michelini; n = 198 total) in Bocas del Toro, Panama, during the major 2005 bleaching event and then monitored pigmentation status and changes live tissue colony size for 8 years (2005-2013). Corals that were bleached in 2005 demonstrated markedly different response trajectories compared to unbleached colony groups, with extensive live tissue loss for bleached corals of all species following bleaching, with mean live tissue losses per colony 9 months postbleaching of 26.2% (±5.4 SE) for O. franksi, 35.7% (±4.7 SE) for S. michelini, and 11.2% (±3.9 SE) for S. siderea. Two species, O. franksi and S. michelini, later recovered to net positive growth, which continued until a second thermal stress event in 2010. Following this event, all species again lost tissue, with previously unbleached colony species groups experiencing greater declines than conspecific sample groups, which were previously bleached, indicating a possible positive acclimative response. However, despite this beneficial effect for previously bleached corals, all groups experienced substantial net tissue loss between 2005 and 2013, indicating that many important Caribbean reef-building corals will likely suffer continued tissue loss and may be unable to maintain current benthic coverage when faced with future thermal stress forecast for the

  6. New tool to manage coral reefs

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    The National Oceanic and Atmospheric Administration is making available a new tool for coral reef managers to monitor the cumulative thermal stress of several coral reefs around the world, including the Great Barrier Reef, and reefs by the Galapagos Islands, the agency announced on 25 February.The agency's "Degree Heating Weeks" product uses satellite-derived information to allow continuous monitoring of the extent and acuteness of thermal stress, which are key predictors of coral bleaching, and which contribute to coral reef degradation.

  7. Thermal tolerances of reef corals in the Gulf: a review of the potential for increasing coral survival and adaptation to climate change through assisted translocation.

    PubMed

    Coles, Steve L; Riegl, Bernhard M

    2013-07-30

    Corals in the Gulf withstand summer temperatures up to 10 °C higher than corals elsewhere and have recovered from extreme temperature events in 10 years or less. This heat-tolerance of Gulf corals has positive implications for the world's coral populations to adapt to increasing water temperatures. However, survival of Gulf corals has been severely tested by 35-37 °C temperatures five times in the last 15 years, each time causing extensive coral bleaching and mortality. Anticipated future temperature increases may therefore challenge survival of already highly stressed Gulf corals. Previously proposed translocation of Gulf corals to introduce temperature-adapted corals outside of the Gulf is assessed and determined to be problematical, and to be considered a tool of last resort. Coral culture and transplantation within the Gulf is feasible for helping maintain coral species populations and preserving genomes and adaptive capacities of Gulf corals that are endangered by future thermal stress events.

  8. Fidelity of the Sr/Ca proxy in recording ocean temperature in the western Atlantic coral Siderastrea siderea

    NASA Astrophysics Data System (ADS)

    Kuffner, Ilsa B.; Roberts, Kelsey E.; Flannery, Jennifer A.; Morrison, Jennifer M.; Richey, Julie N.

    2017-01-01

    Massive corals provide a useful archive of environmental variability, but careful testing of geochemical proxies in corals is necessary to validate the relationship between each proxy and environmental parameter throughout the full range of conditions experienced by the recording organisms. Here we use samples from a coral-growth study to test the hypothesis that Sr/Ca in the coral Siderastrea siderea accurately records sea-surface temperature (SST) in the subtropics (Florida, USA) along 350 km of reef tract. We test calcification rate, measured via buoyant weight, and linear extension (LE) rate, estimated with Alizarin Red-S staining, as predictors of variance in the Sr/Ca records of 39 individual S. siderea corals grown at four outer-reef locations next to in-situ temperature loggers during two, year-long periods. We found that corals with calcification rates < 1.7 mg cm-2 d-1 or < 1.7 mm yr-1 LE returned spuriously high Sr/Ca values, leading to a cold-bias in Sr/Ca-based SST estimates. The threshold-type response curves suggest that extension rate can be used as a quality-control indicator during sample and drill-path selection when using long cores for SST paleoreconstruction. For our corals that passed this quality control step, the Sr/Ca-SST proxy performed well in estimating mean annual temperature across three sites spanning 350 km of the Florida reef tract. However, there was some evidence that extreme temperature stress in 2010 (cold snap) and 2011 (SST above coral-bleaching threshold) may have caused the corals not to record the temperature extremes. Known stress events could be avoided during modern calibrations of paleoproxies.<abstract type="synopsis">Plain Language Summary<span class="hlt">Coral</span> skeletons are used to decipher past environmental conditions in the ocean because they live for centuries and produce annual growth bands much like tree rings. Along with measuring <span class="hlt">coral</span> growth rates in the past, <span class="hlt">coral</span> skeletons can be chemically sampled to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://publications.nigms.nih.gov/insidelifescience/bleach-vs-bacteria.html','NIH-MEDLINEPLUS'); return false;" href="https://publications.nigms.nih.gov/insidelifescience/bleach-vs-bacteria.html"><span><span class="hlt">Bleach</span> vs. Bacteria</span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... Inside Life Science > <span class="hlt">Bleach</span> vs. Bacteria Inside Life Science View All Articles | Inside Life Science Home Page <span class="hlt">Bleach</span> vs. Bacteria By Sharon Reynolds ... For Proteins, Form Shapes Function This Inside Life Science article also appears on LiveScience . Learn about related ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18565794','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18565794"><span>Climate change, global warming and <span class="hlt">coral</span> reefs: modelling the effects of temperature.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Crabbe, M James C</p> <p>2008-10-01</p> <p>Climate change and global warming have severe consequences for the survival of scleractinian (reef-building) <span class="hlt">corals</span> and their associated ecosystems. This review summarizes recent literature on the influence of temperature on <span class="hlt">coral</span> growth, <span class="hlt">coral</span> <span class="hlt">bleaching</span>, and modelling the effects of high temperature on <span class="hlt">corals</span>. Satellite-based sea surface temperature (SST) and <span class="hlt">coral</span> <span class="hlt">bleaching</span> information available on the internet is an important tool in monitoring and modelling <span class="hlt">coral</span> responses to temperature. Within the narrow temperature range for <span class="hlt">coral</span> growth, <span class="hlt">corals</span> can respond to rate of temperature change as well as to temperature per se. We need to continue to develop models of how non-steady-state processes such as global warming and climate change will affect <span class="hlt">coral</span> reefs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19214783','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19214783"><span>Increased light intensity induces heat shock protein Hsp60 in <span class="hlt">coral</span> species.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chow, Ari M; Ferrier-Pagès, Christine; Khalouei, Sam; Reynaud, Stéphanie; Brown, Ian R</p> <p>2009-09-01</p> <p>The effect of increased light intensity and heat stress on heat shock protein Hsp60 was examined in two <span class="hlt">coral</span> species using a branched <span class="hlt">coral</span> and a laminar <span class="hlt">coral</span>, selected for their different resistance to environmental perturbation. Transient Hsp60 induction was observed in the laminar <span class="hlt">coral</span> following either light or thermal stress. Sustained induction was observed when these stresses were combined. The branched <span class="hlt">coral</span> exhibited comparatively weak transient Hsp60 induction after heat stress and no detectable induction following light stress, consistent with its susceptibility to <span class="hlt">bleaching</span> in native environments compared to the laminar <span class="hlt">coral</span>. Our observations also demonstrate that increased light intensity and heat stress exhibited a greater negative impact on the photosynthetic capacity of environmentally sensitive branched <span class="hlt">coral</span> than the more resistant laminar <span class="hlt">coral</span>. This supports a correlation between stress induction of Hsp60 and (a) ability to counter perturbation of photosynthetic capacity by light and heat stress and (b) resistance to environmentally induced <span class="hlt">coral</span> <span class="hlt">bleaching</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=237623&keyword=Solar+AND+System&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78754187&CFTOKEN=29233450','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=237623&keyword=Solar+AND+System&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78754187&CFTOKEN=29233450"><span>Comparative sensitivity of six scleractinian <span class="hlt">corals</span> to temperature and solar radiation</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Scleractinian <span class="hlt">corals</span> were subjected to six combinations of temperature and solar radiation regimes to evaluate their effects on <span class="hlt">coral</span> <span class="hlt">bleaching</span>, survival, and tissue surface area changes during and after an exposure period. A recirculating <span class="hlt">coral</span> exposure system was coupled to a ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFMOS21B0194F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFMOS21B0194F"><span>A Water Tank Study of the Effects of Seawater Temperature on <span class="hlt">Coral</span> Metabolism and Changes in Chemical Compositions in Seawater</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujimura, H.; Arakaki, T.; Hamdun, A. M.; Oomori, T.</p> <p>2002-12-01</p> <p>For the past several years, large-scale <span class="hlt">coral</span> <span class="hlt">bleaching</span> has been observed in many <span class="hlt">coral</span> reef areas around the world. <span class="hlt">Coral</span> <span class="hlt">bleaching</span> is considered to be caused mainly by high seawater temperature together with other factors such as strong UV-light and changes in salinity. However, the mechanism of <span class="hlt">coral</span> <span class="hlt">bleaching</span> is not clearly understood. We have conducted experiments using water tanks under well-controlled light and temperature conditions to elucidate the effects of seawater temperature on <span class="hlt">coral</span>_fs metabolism and changes in chemical compositions in the seawater around the <span class="hlt">coral</span>. Metabolism of <span class="hlt">coral</span> was studied by analyzing changes in seawater chemical compositions. <span class="hlt">Coral</span> specimen used in our experiment, Goniastrea aspera, was collected from northern shore of Okinawa island, Japan. pH, nitrate ion, dissolved organic carbon, and alkalinity were measured. Photochemically formed hydroxyl radical was also studied in those seawater samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CorRe..35..473K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CorRe..35..473K"><span>Climate-driven <span class="hlt">coral</span> reorganisation influences aggressive behaviour in juvenile <span class="hlt">coral</span>-reef fishes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kok, Judith E.; Graham, Nicholas A. J.; Hoogenboom, Mia O.</p> <p>2016-06-01</p> <p>Globally, habitat degradation is altering the abundance and diversity of species in a variety of ecosystems. This study aimed to determine how habitat degradation, in terms of changing <span class="hlt">coral</span> composition under climate change, affected abundance, species richness and aggressive behaviour of juveniles of three damselfishes ( Pomacentrus moluccensis, P. amboinensis and Dischistodus perspicillatus, in order of decreasing reliance on <span class="hlt">coral</span>). Patch reefs were constructed to simulate two types of reefs: present-day reefs that are vulnerable to climate-induced <span class="hlt">coral</span> <span class="hlt">bleaching</span>, and reefs with more <span class="hlt">bleaching</span>-robust <span class="hlt">coral</span> taxa, thereby simulating the likely future of <span class="hlt">coral</span> reefs under a warming climate. Fish communities were allowed to establish naturally on the reefs during the summer recruitment period. Climate-robust reefs had lower total species richness of <span class="hlt">coral</span>-reef fishes than climate-vulnerable reefs, but total fish abundance was not significantly different between reef types (pooled across all species and life-history stages). The nature of aggressive interactions, measured as the number of aggressive chases, varied according to <span class="hlt">coral</span> composition; on climate-robust reefs, juveniles used the substratum less often to avoid aggression from competitors, and interspecific aggression became relatively more frequent than intraspecific aggression for juveniles of the <span class="hlt">coral</span>-obligate P. moluccensis. This study highlights the importance of <span class="hlt">coral</span> composition as a determinant of behaviour and diversity of <span class="hlt">coral</span>-reef fishes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17384666','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17384666"><span>The role of microorganisms in <span class="hlt">coral</span> health, disease and evolution.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rosenberg, Eugene; Koren, Omry; Reshef, Leah; Efrony, Rotem; Zilber-Rosenberg, Ilana</p> <p>2007-05-01</p> <p><span class="hlt">Coral</span> microbiology is an emerging field, driven largely by a desire to understand, and ultimately prevent, the worldwide destruction of <span class="hlt">coral</span> reefs. The mucus layer, skeleton and tissues of healthy <span class="hlt">corals</span> all contain large populations of eukaryotic algae, bacteria and archaea. These microorganisms confer benefits to their host by various mechanisms, including photosynthesis, nitrogen fixation, the provision of nutrients and infection prevention. Conversely, in conditions of environmental stress, certain microorganisms cause <span class="hlt">coral</span> <span class="hlt">bleaching</span> and other diseases. Recent research indicates that <span class="hlt">corals</span> can develop resistance to specific pathogens and adapt to higher environmental temperatures. To explain these findings the <span class="hlt">coral</span> probiotic hypothesis proposes the occurrence of a dynamic relationship between symbiotic microorganisms and <span class="hlt">corals</span> that selects for the <span class="hlt">coral</span> holobiont that is best suited for the prevailing environmental conditions. Generalization of the <span class="hlt">coral</span> probiotic hypothesis has led us to propose the hologenome theory of evolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21558231','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21558231"><span><span class="hlt">Coral</span>-associated bacterial assemblages: current knowledge and the potential for climate-driven impacts.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mouchka, Morgan E; Hewson, Ian; Harvell, C Drew</p> <p>2010-10-01</p> <p>The importance of associations between microorganisms and their invertebrate hosts is becoming increasingly apparent. An emerging field, driven by the necessity to understand the microbial relationships that both maximize <span class="hlt">coral</span> health and cause <span class="hlt">coral</span> disease, is the study of <span class="hlt">coral</span>-bacteria interactions. In this article, we review our current understanding of the diversity, specificity, development, and functions of <span class="hlt">coral</span>-associated bacteria. We also summarize what is known regarding the role of <span class="hlt">coral</span> microbiota in the health and disease of <span class="hlt">coral</span>. We conduct a meta-analysis to determine whether the presence of unique taxa correlates with the state of <span class="hlt">coral</span> health (i.e. healthy, diseased or <span class="hlt">bleached</span>), as well as whether <span class="hlt">coral</span> reef habitats harbor clusters of distinct taxa. We find that healthy and <span class="hlt">bleached</span> <span class="hlt">corals</span> harbor similar dominant taxa, although <span class="hlt">bleached</span> <span class="hlt">corals</span> had higher proportions of Vibrio and Acidobacteria. Diseased <span class="hlt">corals</span> generally had more Rhodobacter, Clostridia, and Cyanobacteria sequences, and fewer Oceanospirillum sequences. We caution, however, that while 16S rRNA is useful for microbial species identification, it is a poor predictor of habitat or lifestyle, and care should be taken in interpretation of 16S rRNA surveys to identify potential pathogens amongst complex <span class="hlt">coral</span>-microbial assemblages. Finally, we highlight evidence that <span class="hlt">coral</span>-bacterial assemblages could be sensitive to the effects of climatic change. We suggest that the relationship between <span class="hlt">coral</span> and their bacterial associates represents a valuable model that can be applied to the broader discipline of invertebrate-microbial interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1482508','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1482508"><span>Dynamic fragility of oceanic <span class="hlt">coral</span> reef ecosystems</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Graham, Nicholas A. J.; Wilson, Shaun K.; Jennings, Simon; Polunin, Nicholas V. C.; Bijoux, Jude P.; Robinson, Jan</p> <p>2006-01-01</p> <p>As one of the most diverse and productive ecosystems known, and one of the first ecosystems to exhibit major climate-warming impacts (<span class="hlt">coral</span> <span class="hlt">bleaching</span>), <span class="hlt">coral</span> reefs have drawn much scientific attention to what may prove to be their Achilles heel, the thermal sensitivity of reef-building <span class="hlt">corals</span>. Here we show that climate change-driven loss of live <span class="hlt">coral</span>, and ultimately structural complexity, in the Seychelles results in local extinctions, substantial reductions in species richness, reduced taxonomic distinctness, and a loss of species within key functional groups of reef fish. The importance of deteriorating physical structure to these patterns demonstrates the longer-term impacts of <span class="hlt">bleaching</span> on reefs and raises questions over the potential for recovery. We suggest that isolated reef systems may be more susceptible to climate change, despite escaping many of the stressors impacting continental reefs. PMID:16709673</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23063708','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23063708"><span>The northernmost <span class="hlt">coral</span> frontier of the Maldives: The <span class="hlt">coral</span> reefs of Ihavandippolu Atoll under long-term environmental change.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tkachenko, Konstantin S</p> <p>2012-12-01</p> <p>Ihavandippolu, the northernmost atoll of the Maldives, experienced severe <span class="hlt">coral</span> <span class="hlt">bleaching</span> and mortality in 1998 followed by several <span class="hlt">bleaching</span> episodes in the last decade. <span class="hlt">Coral</span> cover in the 11 study sites surveyed in July-December of 2011 in the 3-5 m depth range varied from 1.7 to 51%. Reefs of the islands located in the center of Ihavandippolu lagoon have exhibited a very low <span class="hlt">coral</span> recovery since 1998 and remain mostly degraded 12 years after the impact. At the same time, some reefs, especially in the inner part of the eastern ring of the atoll, demonstrate a high <span class="hlt">coral</span> cover (>40%) with a dominance of branching Acropora that is known to be one of the <span class="hlt">coral</span> genera that is most susceptible to thermal stress. The last severe <span class="hlt">bleaching</span> event in 2010 resulted in high <span class="hlt">coral</span> mortality in some sites of the atoll. Differences in <span class="hlt">coral</span> mortality rates and proportion between "susceptible" and "resistant" taxa in study sites are apparently related to long-term adaptation and local hydrological features that can mitigate thermal impacts. Abundant herbivorous fish observed in the atoll prevent <span class="hlt">coral</span> overgrowth by macroalgae even on degraded reefs. Despite the frequent influence of temperature anomalies and having less geomorphologic refuges for <span class="hlt">coral</span> survivals than other larger Maldivian atolls, a major part of observed <span class="hlt">coral</span> communities in Ihavandippolu Atoll exhibits high resilience and potential for further acclimatization to a changing environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001PNAS...98.5419K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001PNAS...98.5419K"><span>The future of <span class="hlt">coral</span> reefs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knowlton, Nancy</p> <p>2001-05-01</p> <p><span class="hlt">Coral</span> reefs, with their millions of species, have changed profoundly because of the effects of people, and will continue to do so for the foreseeable future. Reefs are subject to many of the same processes that affect other human-dominated ecosystems, but some special features merit emphasis: (i) Many dominant reef builders spawn eggs and sperm into the water column, where fertilization occurs. They are thus particularly vulnerable to Allee effects, including potential extinction associated with chronic reproductive failure. (ii) The <span class="hlt">corals</span> likely to be most resistant to the effects of habitat degradation are small, short-lived "weedy" <span class="hlt">corals</span> that have limited dispersal capabilities at the larval stage. Habitat degradation, together with habitat fragmentation, will therefore lead to the establishment of genetically isolated clusters of inbreeding <span class="hlt">corals</span>. (iii) Increases in average sea temperatures by as little as 1°C, a likely result of global climate change, can cause <span class="hlt">coral</span> "<span class="hlt">bleaching</span>" (the breakdown of <span class="hlt">coral</span>-algal symbiosis), changes in symbiont communities, and <span class="hlt">coral</span> death. (iv) The activities of people near reefs increase both fishing pressure and nutrient inputs. In general, these processes favor more rapidly growing competitors, often fleshy seaweeds, and may also result in explosions of predator populations. (v) Combinations of stress appear to be associated with threshold responses and ecological surprises, including devastating pathogen outbreaks. (vi) The fossil record suggests that <span class="hlt">corals</span> as a group are more likely to suffer extinctions than some of the groups that associate with them, whose habitat requirements may be less stringent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11344288','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11344288"><span>The future of <span class="hlt">coral</span> reefs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Knowlton, N</p> <p>2001-05-08</p> <p><span class="hlt">Coral</span> reefs, with their millions of species, have changed profoundly because of the effects of people, and will continue to do so for the foreseeable future. Reefs are subject to many of the same processes that affect other human-dominated ecosystems, but some special features merit emphasis: (i) Many dominant reef builders spawn eggs and sperm into the water column, where fertilization occurs. They are thus particularly vulnerable to Allee effects, including potential extinction associated with chronic reproductive failure. (ii) The <span class="hlt">corals</span> likely to be most resistant to the effects of habitat degradation are small, short-lived "weedy" <span class="hlt">corals</span> that have limited dispersal capabilities at the larval stage. Habitat degradation, together with habitat fragmentation, will therefore lead to the establishment of genetically isolated clusters of inbreeding <span class="hlt">corals</span>. (iii) Increases in average sea temperatures by as little as 1 degrees C, a likely result of global climate change, can cause <span class="hlt">coral</span> "<span class="hlt">bleaching</span>" (the breakdown of <span class="hlt">coral</span>-algal symbiosis), changes in symbiont communities, and <span class="hlt">coral</span> death. (iv) The activities of people near reefs increase both fishing pressure and nutrient inputs. In general, these processes favor more rapidly growing competitors, often fleshy seaweeds, and may also result in explosions of predator populations. (v) Combinations of stress appear to be associated with threshold responses and ecological surprises, including devastating pathogen outbreaks. (vi) The fossil record suggests that <span class="hlt">corals</span> as a group are more likely to suffer extinctions than some of the groups that associate with them, whose habitat requirements may be less stringent.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/214638','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/214638"><span>Overview of ozone <span class="hlt">bleaching</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sonnenberg, L.B.</p> <p>1995-12-31</p> <p>The potential impact of the pulp and paper industry on the environment may be reduced by replacing chlorine-based <span class="hlt">bleaching</span> reagents with ozone. The reactivity of ozone coupled with the heterogeneity of pulp allows many types of reactions to occur during pulp <span class="hlt">bleaching</span>. Ozone cleaves the aromatic rings and side chain double bonds in lignin in Criegee-type mechanisms. Activated carbon-hydrogen bonds are fragmented in lignin side chains, as well as Cl carbons of {beta}-glycosides, by way of a 1,3 dipolar insertion forming a hydrotrioxide intermediate. Ozone also attacks carbohydrates at acetal oxygens, depolymerizing at the glycosidic bond. Unsaturated sites are ozonated before aliphatic sites resulting in a predominance of lignin reactions over carbohydrate reactions until lignin is substantially removed from the pulp. Important factors in the successful application of ozone <span class="hlt">bleaching</span> include minimizing ozone decomposition and other secondary reactions, reducing exposure of cellulose to high concentrations of ozone and radicals, and promoting uniform exposure of ozone to lignin. The quantity of chlorinated organic compounds in effluents can be drastically reduced by replacing chlorine-based <span class="hlt">bleaching</span> reagents with ozone; less organochlorine is formed and there can be greater recycle of <span class="hlt">bleach</span> plant wastes back to the recovery cycle. Recycling of <span class="hlt">bleach</span> plant waste also reduces total organic loading in the effluent. The toxicity of ozone filtrates is variable compared to conventional filtrates and depends on several parameters including <span class="hlt">bleaching</span> conditions, biological treatment, and target organisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000070388&hterms=Coral+bleaching&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DCoral%2Bbleaching','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000070388&hterms=Coral+bleaching&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DCoral%2Bbleaching"><span><span class="hlt">Corals</span> from Space</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Patzert, William C.</p> <p>1999-01-01</p> <p>The goal of this research is to monitor the health and vigor of <span class="hlt">coral</span> reef ecosystems, and their sensitivity to natural and anthropogenic climate changes. To achieve these lofty goals, this research is investigating the feasibility of using spaceborne high-resolution spectrometers (on the US Landsat, French Systeme Probatoire pour l'Observation de la Terre [SPOT] and/or the Indian Resources Satellite [IRS 1C & 1D] spacecraft) to first map the aerial extent of <span class="hlt">coral</span> reef systems, and second separate the amount of particular <span class="hlt">corals</span>. If this is successful, we could potentially provide a quantum leap in our understanding of <span class="hlt">coral</span> reef systems, as well as provide much needed baseline data to measure future changes in global <span class="hlt">coral</span> reef ecosystems. In collaboration with Tomas Tomascik, Yann Morel, and other colleagues, a series of experiments were planned to coordinate in situ <span class="hlt">coral</span> observations, high-resolution spaceborne imagery (from Landsat, SPOT, and, possibly, IRS IC spacecraft), and NASA Space Shuttle photographs and digital images. Our eventual goal is to develop "<span class="hlt">coral</span> health algorithms" that can be used to assess time series of imagery collected from satellite sensors (Landsat since 1972, SPOT since 1986) in concert with in situ observations. The bad news from last year was that from 1997 to mid- 1998, the extreme cloudiness over southeast Asia due to prolonged smoke from El Nino-related fires and the economic chaos in this region frustrated both our space and reef-based data collection activities. When this volatile situation stabilizes, we will restart these activities. The good news was that in collaboration with Al Strong at the National Oceanic and Atmospheric Administration (NOAA) we had an exciting year operationally using the NOAA's Advanced Very High Resolution Radiometer sensor derived sea surface temperature products to warn of <span class="hlt">coral</span> "<span class="hlt">bleaching</span>" at many locations throughout the tropics. Data from NOAA's satellites showed that during the El Nino of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23959950','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23959950"><span>A <span class="hlt">coral</span> reef refuge in the Red Sea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fine, Maoz; Gildor, Hezi; Genin, Amatzia</p> <p>2013-12-01</p> <p>The stability and persistence of <span class="hlt">coral</span> reefs in the decades to come is uncertain due to global warming and repeated <span class="hlt">bleaching</span> events that will lead to reduced resilience of these ecological and socio-economically important ecosystems. Identifying key refugia is potentially important for future conservation actions. We suggest that the Gulf of Aqaba (GoA) (Red Sea) may serve as a reef refugium due to a unique suite of environmental conditions. Our hypothesis is based on experimental detection of an exceptionally high <span class="hlt">bleaching</span> threshold of northern Red Sea <span class="hlt">corals</span> and on the potential dispersal of <span class="hlt">coral</span> planulae larvae through a selective thermal barrier estimated using an ocean model. We propose that millennia of natural selection in the form of a thermal barrier at the southernmost end of the Red Sea have selected <span class="hlt">coral</span> genotypes that are less susceptible to thermal stress in the northern Red Sea, delaying <span class="hlt">bleaching</span> events in the GoA by at least a century.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25607371','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25607371"><span>Predicting climate-driven regime shifts versus rebound potential in <span class="hlt">coral</span> reefs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Graham, Nicholas A J; Jennings, Simon; MacNeil, M Aaron; Mouillot, David; Wilson, Shaun K</p> <p>2015-02-05</p> <p>Climate-induced <span class="hlt">coral</span> <span class="hlt">bleaching</span> is among the greatest current threats to <span class="hlt">coral</span> reefs, causing widespread loss of live <span class="hlt">coral</span> cover. Conditions under which reefs bounce back from <span class="hlt">bleaching</span> events or shift from <span class="hlt">coral</span> to algal dominance are unknown, making it difficult to predict and plan for differing reef responses under climate change. Here we document and predict long-term reef responses to a major climate-induced <span class="hlt">coral</span> <span class="hlt">bleaching</span> event that caused unprecedented region-wide mortality of Indo-Pacific <span class="hlt">corals</span>. Following loss of >90% live <span class="hlt">coral</span> cover, 12 of 21 reefs recovered towards pre-disturbance live <span class="hlt">coral</span> states, while nine reefs underwent regime shifts to fleshy macroalgae. Functional diversity of associated reef fish communities shifted substantially following <span class="hlt">bleaching</span>, returning towards pre-disturbance structure on recovering reefs, while becoming progressively altered on regime shifting reefs. We identified threshold values for a range of factors that accurately predicted ecosystem response to the <span class="hlt">bleaching</span> event. Recovery was favoured when reefs were structurally complex and in deeper water, when density of juvenile <span class="hlt">corals</span> and herbivorous fishes was relatively high and when nutrient loads were low. Whether reefs were inside no-take marine reserves had no bearing on ecosystem trajectory. Although conditions governing regime shift or recovery dynamics were diverse, pre-disturbance quantification of simple factors such as structural complexity and water depth accurately predicted ecosystem trajectories. These findings foreshadow the likely divergent but predictable outcomes for reef ecosystems in response to climate change, thus guiding improved management and adaptation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28326066','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28326066"><span>Beneficial Microorganisms for <span class="hlt">Corals</span> (BMC): Proposed Mechanisms for <span class="hlt">Coral</span> Health and Resilience.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Peixoto, Raquel S; Rosado, Phillipe M; Leite, Deborah Catharine de Assis; Rosado, Alexandre S; Bourne, David G</p> <p>2017-01-01</p> <p>The symbiotic association between the <span class="hlt">coral</span> animal and its endosymbiotic dinoflagellate partner Symbiodinium is central to the success of <span class="hlt">corals</span>. However, an array of other microorganisms associated with <span class="hlt">coral</span> (i.e., Bacteria, Archaea, Fungi, and viruses) have a complex and intricate role in maintaining homeostasis between <span class="hlt">corals</span> and Symbiodinium. <span class="hlt">Corals</span> are sensitive to shifts in the surrounding environmental conditions. One of the most widely reported responses of <span class="hlt">coral</span> to stressful environmental conditions is <span class="hlt">bleaching</span>. During this event, <span class="hlt">corals</span> expel Symbiodinium cells from their gastrodermal tissues upon experiencing extended seawater temperatures above their thermal threshold. An array of other environmental stressors can also destabilize the <span class="hlt">coral</span> microbiome, resulting in compromised health of the host, which may include disease and mortality in the worst scenario. However, the exact mechanisms by which the <span class="hlt">coral</span> microbiome supports <span class="hlt">coral</span> health and increases resilience are poorly understood. Earlier studies of <span class="hlt">coral</span> microbiology proposed a <span class="hlt">coral</span> probiotic hypothesis, wherein a dynamic relationship exists between <span class="hlt">corals</span> and their symbiotic microorganisms, selecting for the <span class="hlt">coral</span> holobiont that is best suited for the prevailing environmental conditions. Here, we discuss the microbial-host relationships within the <span class="hlt">coral</span> holobiont, along with their potential roles in maintaining <span class="hlt">coral</span> health. We propose the term BMC (Beneficial Microorganisms for <span class="hlt">Corals</span>) to define (specific) symbionts that promote <span class="hlt">coral</span> health. This term and concept are analogous to the term Plant Growth Promoting Rhizosphere (PGPR), which has been widely explored and manipulated in the agricultural industry for microorganisms that inhabit the rhizosphere and directly or indirectly promote plant growth and development through the production of regulatory signals, antibiotics and nutrients. Additionally, we propose and discuss the potential mechanisms of the effects of BMC on <span class="hlt">corals</span>, suggesting</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5339234','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5339234"><span>Beneficial Microorganisms for <span class="hlt">Corals</span> (BMC): Proposed Mechanisms for <span class="hlt">Coral</span> Health and Resilience</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Peixoto, Raquel S.; Rosado, Phillipe M.; Leite, Deborah Catharine de Assis; Rosado, Alexandre S.; Bourne, David G.</p> <p>2017-01-01</p> <p>The symbiotic association between the <span class="hlt">coral</span> animal and its endosymbiotic dinoflagellate partner Symbiodinium is central to the success of <span class="hlt">corals</span>. However, an array of other microorganisms associated with <span class="hlt">coral</span> (i.e., Bacteria, Archaea, Fungi, and viruses) have a complex and intricate role in maintaining homeostasis between <span class="hlt">corals</span> and Symbiodinium. <span class="hlt">Corals</span> are sensitive to shifts in the surrounding environmental conditions. One of the most widely reported responses of <span class="hlt">coral</span> to stressful environmental conditions is <span class="hlt">bleaching</span>. During this event, <span class="hlt">corals</span> expel Symbiodinium cells from their gastrodermal tissues upon experiencing extended seawater temperatures above their thermal threshold. An array of other environmental stressors can also destabilize the <span class="hlt">coral</span> microbiome, resulting in compromised health of the host, which may include disease and mortality in the worst scenario. However, the exact mechanisms by which the <span class="hlt">coral</span> microbiome supports <span class="hlt">coral</span> health and increases resilience are poorly understood. Earlier studies of <span class="hlt">coral</span> microbiology proposed a <span class="hlt">coral</span> probiotic hypothesis, wherein a dynamic relationship exists between <span class="hlt">corals</span> and their symbiotic microorganisms, selecting for the <span class="hlt">coral</span> holobiont that is best suited for the prevailing environmental conditions. Here, we discuss the microbial-host relationships within the <span class="hlt">coral</span> holobiont, along with their potential roles in maintaining <span class="hlt">coral</span> health. We propose the term BMC (Beneficial Microorganisms for <span class="hlt">Corals</span>) to define (specific) symbionts that promote <span class="hlt">coral</span> health. This term and concept are analogous to the term Plant Growth Promoting Rhizosphere (PGPR), which has been widely explored and manipulated in the agricultural industry for microorganisms that inhabit the rhizosphere and directly or indirectly promote plant growth and development through the production of regulatory signals, antibiotics and nutrients. Additionally, we propose and discuss the potential mechanisms of the effects of BMC on <span class="hlt">corals</span>, suggesting</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22447198','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22447198"><span><span class="hlt">Coral</span> recovery may not herald the return of fishes on damaged <span class="hlt">coral</span> reefs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bellwood, David R; Baird, Andrew H; Depczynski, Martial; González-Cabello, Alonso; Hoey, Andrew S; Lefèvre, Carine D; Tanner, Jennifer K</p> <p>2012-10-01</p> <p>The dynamic nature of <span class="hlt">coral</span> reefs offers a rare opportunity to examine the response of ecosystems to disruption due to climate change. In 1998, the Great Barrier Reef experienced widespread <span class="hlt">coral</span> <span class="hlt">bleaching</span> and mortality. As a result, cryptobenthic fish assemblages underwent a dramatic phase-shift. Thirteen years, and up to 96 fish generations later, the cryptobenthic fish assemblage has not returned to its pre-<span class="hlt">bleach</span> configuration. This is despite <span class="hlt">coral</span> abundances returning to, or exceeding, pre-<span class="hlt">bleach</span> values. The post-<span class="hlt">bleach</span> fish assemblage exhibits no evidence of recovery. If these short-lived fish species are a model for their longer-lived counterparts, they suggest that (1) the full effects of the 1998 <span class="hlt">bleaching</span> event on long-lived fish populations have yet to be seen, (2) it may take decades, or more, before recovery or regeneration of these long-lived species will begin, and (3) fish assemblages may not recover to their previous composition despite the return of <span class="hlt">corals</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28275004','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28275004"><span>Reactive oxygen species (ROS) and dimethylated sulphur compounds in <span class="hlt">coral</span> explants under acute thermal stress.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gardner, Stephanie G; Raina, Jean-Baptiste; Ralph, Peter J; Petrou, Katherina</p> <p>2017-03-08</p> <p><span class="hlt">Coral</span> <span class="hlt">bleaching</span> is intensifying with global climate change. While the causes for these catastrophic events are well understood, the cellular mechanism that triggers <span class="hlt">bleaching</span> is not well established. Our understanding of <span class="hlt">coral</span> <span class="hlt">bleaching</span> processes is hindered by the lack of robust methods for studying interactions between host and symbiont at the single-cell level. Here we exposed <span class="hlt">coral</span> explants to acute thermal stress and measured oxidative stress, more specifically, reactive oxygen species (ROS), in individual symbiont cells. Furthermore, we measured concentrations of dimethylsulphoniopropionate (DMSP) and dimethylsulphoxide (DMSO) to elucidate the role of these compounds in <span class="hlt">coral</span> antioxidant function. This work demonstrates the application of <span class="hlt">coral</span> explants for investigating <span class="hlt">coral</span> physiology and biochemistry under thermal stress and delivers a new approach to study host-symbiont interactions at the microscale, allowing us to directly link intracellular ROS with DMSP and DMSO dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19769097','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19769097"><span>Improved water quality can ameliorate effects of climate change on <span class="hlt">corals</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wooldridge, Scott A; Done, Terence J</p> <p>2009-09-01</p> <p>The threats of wide-scale <span class="hlt">coral</span> <span class="hlt">bleaching</span> and reef demise associated with anthropogenic climate change are widely known. Moreover, rates of genetic adaptation and/or changes in the <span class="hlt">coral</span>-zooxanthella partnerships are considered unlikely to be sufficiently fast for <span class="hlt">corals</span> to acquire increased physiological resistance to increasing sea temperatures and declining pH. However, it has been suggested that <span class="hlt">coral</span> reef resilience to climate change may be improved by good local management of <span class="hlt">coral</span> reefs, including management of water quality. Here, using major data sets from the Great Barrier Reef (GBR), Australia, we investigate geographic patterns of <span class="hlt">coral</span> <span class="hlt">bleaching</span> in 1998 and 2002 and outline a synergism between heat stress and nutrient flux as a major causative mechanism for those patterns. The study provides the first concrete evidence for the oft-expressed belief that improved <span class="hlt">coral</span> reef management will increase the regional-scale survival prospects of <span class="hlt">coral</span> reefs to global climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22006333','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22006333"><span>Macroalgal terpenes function as allelopathic agents against reef <span class="hlt">corals</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rasher, Douglas B; Stout, E Paige; Engel, Sebastian; Kubanek, Julia; Hay, Mark E</p> <p>2011-10-25</p> <p>During recent decades, many tropical reefs have transitioned from <span class="hlt">coral</span> to macroalgal dominance. These community shifts increase the frequency of algal-<span class="hlt">coral</span> interactions and may suppress <span class="hlt">coral</span> recovery following both anthropogenic and natural disturbance. However, the extent to which macroalgae damage <span class="hlt">corals</span> directly, the mechanisms involved, and the species specificity of algal-<span class="hlt">coral</span> interactions remain uncertain. Here, we conducted field experiments demonstrating that numerous macroalgae directly damage <span class="hlt">corals</span> by transfer of hydrophobic allelochemicals present on algal surfaces. These hydrophobic compounds caused <span class="hlt">bleaching</span>, decreased photosynthesis, and occasionally death of <span class="hlt">corals</span> in 79% of the 24 interactions assayed (three <span class="hlt">corals</span> and eight algae). <span class="hlt">Coral</span> damage generally was limited to sites of algal contact, but algae were unaffected by contact with <span class="hlt">corals</span>. Artificial mimics for shading and abrasion produced no impact on <span class="hlt">corals</span>, and effects of hydrophobic surface extracts from macroalgae paralleled effects of whole algae; both findings suggest that local effects are generated by allelochemical rather than physical mechanisms. Rankings of macroalgae from most to least allelopathic were similar across the three <span class="hlt">coral</span> genera tested. However, <span class="hlt">corals</span> varied markedly in susceptibility to allelopathic algae, with globally declining <span class="hlt">corals</span> such as Acropora more strongly affected. Bioassay-guided fractionation of extracts from two allelopathic algae led to identification of two loliolide derivatives from the red alga Galaxaura filamentosa and two acetylated diterpenes from the green alga Chlorodesmis fastigiata as potent allelochemicals. Our results highlight a newly demonstrated but potentially widespread competitive mechanism to help explain the lack of <span class="hlt">coral</span> recovery on many present-day reefs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMOS13A1217L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS13A1217L"><span>Modeling the effects of climate change and acidification on global <span class="hlt">coral</span> reefs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Logan, C. A.; Donner, S. D.; Eakin, C.; Dunne, J. P.</p> <p>2010-12-01</p> <p>Climate warming threatens to increase the frequency of mass <span class="hlt">coral</span> <span class="hlt">bleaching</span> events. Meanwhile, ocean acidification may increase susceptibility to these events and slow the recovery of <span class="hlt">corals</span> following <span class="hlt">bleaching</span>. Using future sea surface warming scenarios from global coupled climate models, previous studies have estimated that <span class="hlt">corals</span> will experience biannual <span class="hlt">bleaching</span> events by mid-century unless they are able to acclimatize or adapt at a rate of ~0.2-1.0°C per decade. Empirical studies also show that certain <span class="hlt">coral</span> ecotypes may be more resistant to <span class="hlt">bleaching</span> than others (e.g. massive vs. branching). Likewise, more variable thermal history may play a significant role in increasing resistance to <span class="hlt">bleaching</span>. Better quantifying the impacts of climate change and ocean acidification on <span class="hlt">coral</span> reefs under different future scenarios is critical to making proactive decisions about both mitigation of greenhouse gas emissions and adaptation to climate change. Proposed here is a model that uses two of the ESM2 GFDL models and combines several previous attempts at modeling climate change effects. This model incorporates thermal history and adaptability into a modified Degree Heating Week <span class="hlt">bleaching</span> threshold. The model is designed to examine the effects of rising SSTs alone as well as in combination with ocean acidification and other factors to predict future global <span class="hlt">coral</span> reef <span class="hlt">bleaching</span> frequency and response by <span class="hlt">coral</span> ecotype. The ESM2 GFDL models are validated for use in <span class="hlt">coral</span> reef areas by comparing model results against historical SST satellite data for the years 1985-2006 at 4km and 50km spatial resolutions to assess the models’ reproducibility of mean annual temperature, range, and variability. The modified <span class="hlt">bleaching</span> threshold is tested against observational <span class="hlt">bleaching</span> records in well-documented areas (e.g., Great Barrier Reef).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005CorRe..24..463H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005CorRe..24..463H"><span>Stress response of two <span class="hlt">coral</span> species in the Kavaratti atoll of the Lakshadweep Archipelago, India</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harithsa, Shashank; Raghukumar, Chandralata; Dalal, S. G.</p> <p>2005-11-01</p> <p>Frequent occurrences of <span class="hlt">coral</span> <span class="hlt">bleaching</span> and the ensuing damage to <span class="hlt">coral</span> reefs have generated interest in documenting stress responses that precede <span class="hlt">bleaching</span>. The objective of this study was to assess and compare physiological changes in healthy, semi-<span class="hlt">bleached</span> and totally <span class="hlt">bleached</span> colonies of two <span class="hlt">coral</span> species, Porites lutea and Acropora formosa, during a natural <span class="hlt">bleaching</span> event in the Lakshadweep Archipelago in the Arabian Sea to determine the traits that will be useful in the diagnosis of <span class="hlt">coral</span> health. In April 2002, three “health conditions” were observed as “appearing healthy,” “semi-bleached” and “bleached” specimens for two dominant and co-occurring <span class="hlt">coral</span> species in these islands. Changes in the pigment composition, zooxanthellae density (ZD), mitotic index (MI) of zooxanthellae, RNA/DNA ratios and protein profile in the two <span class="hlt">coral</span> species showing different levels of <span class="hlt">bleaching</span> in the field were compared to address the hypothesis of no difference in health condition between species and <span class="hlt">bleaching</span> status. The loss in chlorophyll (chl) a, chl c and ZD in the transitional stage of semi-<span class="hlt">bleaching</span> in the branched <span class="hlt">coral</span> A. formosa was 80, 75 and 80%, respectively. The losses were much less in the massive <span class="hlt">coral</span> P. lutea, being 20, 50 and 25%, respectively. The decrease in zooxanthellar density and chl a was accompanied by an increased MI of zooxanthellae and RNA/DNA ratios in both the species. There was an increase in accumulation of lipofuscin granules in partially <span class="hlt">bleached</span> P. lutea tissue, which is an indication of cellular senescence. Multivariate statistical analyses showed that colonies of P. lutea ranked in different health conditions differed significantly in chl a, chl c, ZD, RNA/DNA ratios, and protein concentrations, whereas in A. formosa chl a, chl c, chl a/ c, phaeopigments and MI contributed to the variance between health conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22194880','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22194880"><span>Regulation of apoptotic pathways by Stylophora pistillata (Anthozoa, Pocilloporidae) to survive thermal stress and <span class="hlt">bleaching</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kvitt, Hagit; Rosenfeld, Hanna; Zandbank, Keren; Tchernov, Dan</p> <p>2011-01-01</p> <p>Elevated seawater temperatures are associated with <span class="hlt">coral</span> <span class="hlt">bleaching</span> events and related mortality. Nevertheless, some <span class="hlt">coral</span> species are able to survive <span class="hlt">bleaching</span> and recover. The apoptotic responses associated to this ability were studied over 3 years in the <span class="hlt">coral</span> Stylophora pistillata from the Gulf of Eilat subjected to long term thermal stress. These include caspase activity and the expression profiles of the S. pistillata caspase and Bcl-2 genes (StyCasp and StyBcl-2-like) cloned in this study. In <span class="hlt">corals</span> exposed to thermal stress (32 or 34°C), caspase activity and the expression levels of the StyBcl-2-like gene increased over time (6-48 h) and declined to basal levels within 72 h of thermal stress. Distinct transcript levels were obtained for the StyCasp gene, with stimulated expression from 6 to 48 h of 34°C thermal stress, coinciding with the onset of <span class="hlt">bleaching</span>. Increased cell death was detected in situ only between 6 to 48 h of stress and was limited to the gastroderm. The <span class="hlt">bleached</span> <span class="hlt">corals</span> survived up to one month at 32°C, and recovered back symbionts when placed at 24°C. These results point to a two-stage response in <span class="hlt">corals</span> that withstand thermal stress: (i) the onset of apoptosis, accompanied by rapid activation of anti-oxidant/anti-apoptotic mediators that block the progression of apoptosis to other cells and (ii) acclimatization of the <span class="hlt">coral</span> to the chronic thermal stress alongside the completion of symbiosis breakdown. Accordingly, the <span class="hlt">coral</span>'s ability to rapidly curb apoptosis appears to be the most important trait affecting the <span class="hlt">coral</span>'s thermotolerance and survival.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990CorRe...8..155J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990CorRe...8..155J"><span>Response of Hawaiian and other Indo-Pacific reef <span class="hlt">corals</span> to elevated temperature</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jokiel, P. L.; Coles, S. L.</p> <p>1990-04-01</p> <p>Loss of symbiotic zooxanthellae, or “bleaching” is one of the first visible signs of thermal stress. Critical threshold temperatures for <span class="hlt">coral</span> <span class="hlt">bleaching</span> vary geographically, but can be expressed universally as fixed increments relative to the historical mean local summer maximum. <span class="hlt">Bleaching</span> can be induced by short-term exposure (i.e. 1 2 days) at temperature elevations of 3°C to 4°C above normal summer ambient or by long-term exposure (i.e. several weeks) at elevations of 1°C to 2°C. <span class="hlt">Corals</span> in both tropical and subtropical locations live at temperatures close to their lethal limits during the summer months. Temperature elevations above summer ambient, but still below the <span class="hlt">bleaching</span> threshold, can impair growth and reproduction. Temperature and light interact synergistically; high light accelerates <span class="hlt">bleaching</span> caused by elevated temperature. <span class="hlt">Bleaching</span> susceptibility is correlated with respiration rate. Any factor that increases respiration (such as high incident light) accelerates <span class="hlt">bleaching</span> at higher temperatures. Ultraviolet (UV) radiation is a detrimental factor associated with solar radiation. Increased UV due to thinning of the earth's protective ozone layer may aggravate <span class="hlt">bleaching</span> and mortality caused by global warming. A warming trend in Hawaiian waters has been observed over the past decade. In 1986, 1987 and 1988 Hawaiian <span class="hlt">corals</span> were perilously close to their <span class="hlt">bleaching</span> threshold during the summer months, and localized <span class="hlt">bleachings</span> did occur. In some cases, local warming of surface water on shallow reef flats exceeded this threshold temperature and caused localized <span class="hlt">coral</span> <span class="hlt">bleaching</span>. In other cases, heating of large mesoscale eddies in the lee of the larger islands apparently caused wide-scale <span class="hlt">bleaching</span> of the most sensitive <span class="hlt">coral</span> species ( Pocillopora meandrina) to depths of 20 m. A continuation of the warming trend in Hawaii would lead to mass <span class="hlt">bleachings</span> similar to those observed recently in other geographic locations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15757739','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15757739"><span>Effects of algal turfs and sediment on <span class="hlt">coral</span> settlement.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Birrell, Chico L; McCook, Laurence J; Willis, Bette L</p> <p>2005-01-01</p> <p>Successful settlement and recruitment of <span class="hlt">corals</span> is critical to the resilience of <span class="hlt">coral</span> reefs. Given that many degraded reefs are dominated by benthic algae, recovery of <span class="hlt">coral</span> populations after <span class="hlt">bleaching</span> and other disturbances requires successful settlement amidst benthic algae. Algal turfs often accumulate sediments, sediments are known to inhibit <span class="hlt">coral</span> settlement, and reefs with high inputs of terrestrial sediments are often dominated by turfs. We investigated the impacts of two algal turf assemblages, and of sediment deposits, on settlement of the <span class="hlt">coral</span> Acropora millepora (Ehrenberg). Adding sediment reduced <span class="hlt">coral</span> settlement, but the effects of different algal turfs varied. In one case, algal turfs inhibited <span class="hlt">coral</span> settlement, whereas the other turf only inhibited settlement when combined with sediments. These results provide the first direct, experimental evidence of effects of filamentous algal turfs on <span class="hlt">coral</span> settlement, the variability in those effects, and the potential combined effects of algal turfs and trapped sediments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19323170','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19323170"><span>Symbiont diversity may help <span class="hlt">coral</span> reefs survive moderate climate change.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Baskett, Marissa L; Gaines, Steven D; Nisbet, Roger M</p> <p>2009-01-01</p> <p>Given climate change, thermal stress-related mass <span class="hlt">coral-bleaching</span> events present one of the greatest anthropogenic threats to <span class="hlt">coral</span> reefs. While <span class="hlt">corals</span> and their symbiotic algae may respond to future temperatures through genetic adaptation and shifts in community compositions, the climate may change too rapidly for <span class="hlt">coral</span> response. To test this potential for response, here we develop a model of <span class="hlt">coral</span> and symbiont ecological dynamics and symbiont evolutionary dynamics. Model results without variation in symbiont thermal tolerance predict <span class="hlt">coral</span> reef collapse within decades under multiple future climate scenarios, consistent with previous threshold-based predictions. However, model results with genetic or community-level variation in symbiont thermal tolerance can predict <span class="hlt">coral</span> reef persistence into the next century, provided low enough greenhouse gas emissions occur. Therefore, the level of greenhouse gas emissions will have a significant effect on the future of <span class="hlt">coral</span> reefs, and accounting for biodiversity and biological dynamics is vital to estimating the size of this effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21319458','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21319458"><span>Assessment of survival, mortality and recovery of <span class="hlt">coral</span> reefs of East Kish Island, Persian Gulf.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jami, M J; Salehduost, A; Negarestan, H</p> <p>2010-10-15</p> <p><span class="hlt">Coral</span> reefs are specialized communities that develop clear, well-lit tropical and subtropical water; they provide shelter and canopy for great variety of organisms, living in mean temperature of 20 degrees C. <span class="hlt">Coral</span> <span class="hlt">Bleaching</span> and mortality have been associated with elevated seawater temperature. The aim of the study was to investigate <span class="hlt">coral</span> <span class="hlt">bleaching</span> and evaluate health condition of the <span class="hlt">corals</span>. Distribution of <span class="hlt">coral</span> reefs around Kish Island was determined by the Timed Swim (TS) technique. This survey carried out in 2 times (May and October, 2009) in 2 depths of 3-5 m and 6-10 m. Two Divers swam in constant speed for a set amount of time in three dive sites. The timed swim survey around the Kish Island showed that the most healthy live hard <span class="hlt">coral</span> assemblages were found in the site called Persian Gulf seaport, whereas the greatest percentage of <span class="hlt">bleached</span> <span class="hlt">corals</span> were located in Jurassic Park station, located at the southeast of the Island. Branching <span class="hlt">corals</span> (Acropora sp.) were <span class="hlt">bleached</span> among all 3 stations and no sign of recovery could be detected. In Big <span class="hlt">coral</span> site suitable substrate for accumulation of living organisms including Echinometra mathaie (sea urchin) existed due to presence of great amount of algae on dead <span class="hlt">corals</span> and rocks. Based on the observation, it seems that the cause of reef destruction in Kish Island fall in to two categories, natural and human impacts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23027961','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23027961"><span>The 27-year decline of <span class="hlt">coral</span> cover on the Great Barrier Reef and its causes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>De'ath, Glenn; Fabricius, Katharina E; Sweatman, Hugh; Puotinen, Marji</p> <p>2012-10-30</p> <p>The world's <span class="hlt">coral</span> reefs are being degraded, and the need to reduce local pressures to offset the effects of increasing global pressures is now widely recognized. This study investigates the spatial and temporal dynamics of <span class="hlt">coral</span> cover, identifies the main drivers of <span class="hlt">coral</span> mortality, and quantifies the rates of potential recovery of the Great Barrier Reef. Based on the world's most extensive time series data on reef condition (2,258 surveys of 214 reefs over 1985-2012), we show a major decline in <span class="hlt">coral</span> cover from 28.0% to 13.8% (0.53% y(-1)), a loss of 50.7% of initial <span class="hlt">coral</span> cover. Tropical cyclones, <span class="hlt">coral</span> predation by crown-of-thorns starfish (COTS), and <span class="hlt">coral</span> <span class="hlt">bleaching</span> accounted for 48%, 42%, and 10% of the respective estimated losses, amounting to 3.38% y(-1) mortality rate. Importantly, the relatively pristine northern region showed no overall decline. The estimated rate of increase in <span class="hlt">coral</span> cover in the absence of cyclones, COTS, and <span class="hlt">bleaching</span> was 2.85% y(-1), demonstrating substantial capacity for recovery of reefs. In the absence of COTS, <span class="hlt">coral</span> cover would increase at 0.89% y(-1), despite ongoing losses due to cyclones and <span class="hlt">bleaching</span>. Thus, reducing COTS populations, by improving water quality and developing alternative control measures, could prevent further <span class="hlt">coral</span> decline and improve the outlook for the Great Barrier Reef. Such strategies can, however, only be successful if climatic conditions are stabilized, as losses due to <span class="hlt">bleaching</span> and cyclones will otherwise increase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010GeoRL..3715602W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010GeoRL..3715602W"><span>Response of <span class="hlt">coral</span> reefs to climate change: Expansion and demise of the southernmost Pacific <span class="hlt">coral</span> reef</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Woodroffe, Colin D.; Brooke, Brendan P.; Linklater, Michelle; Kennedy, David M.; Jones, Brian G.; Buchanan, Cameron; Mleczko, Richard; Hua, Quan; Zhao, Jian-xin</p> <p>2010-08-01</p> <p><span class="hlt">Coral</span> reefs track sea level and are particularly sensitive to changes in climate. Reefs are threatened by global warming, with many experiencing increased <span class="hlt">coral</span> <span class="hlt">bleaching</span>. Warmer sea surface temperatures might enable reef expansion into mid latitudes. Here we report multibeam sonar and coring that reveal an extensive relict <span class="hlt">coral</span> reef around Lord Howe Island, which is fringed by the southernmost reef in the Pacific Ocean. The relict reef, in water depths of 25-50 m, flourished in early Holocene and covered an area more than 20 times larger than the modern reef. Radiocarbon and uranium-series dating indicates that <span class="hlt">corals</span> grew between 9000 and 7000 years ago. The reef was subsequently drowned, and backstepped to its modern limited extent. This relict reef, with localised re-establishment of <span class="hlt">corals</span> in the past three millennia, could become a substrate for reef expansion in response to warmer temperatures, anticipated later this century and beyond, if <span class="hlt">corals</span> are able to recolonise its surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26648385','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26648385"><span>Caribbean mesophotic <span class="hlt">coral</span> ecosystems are unlikely climate change refugia.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Smith, Tyler B; Gyory, Joanna; Brandt, Marilyn E; Miller, William J; Jossart, Jonathan; Nemeth, Richard S</p> <p>2016-08-01</p> <p>Deeper <span class="hlt">coral</span> reefs experience reduced temperatures and light and are often shielded from localized anthropogenic stressors such as pollution and fishing. The deep reef refugia hypothesis posits that light-dependent stony <span class="hlt">coral</span> species at deeper depths are buffered from thermal stress and will avoid <span class="hlt">bleaching</span>-related mass mortalities caused by increasing sea surface temperatures under climate change. This hypothesis has not been tested because data collection on deeper <span class="hlt">coral</span> reefs is difficult. Here we show that deeper (mesophotic) reefs, 30-75 m depth, in the Caribbean are not refugia because they have lower <span class="hlt">bleaching</span> threshold temperatures than shallow reefs. Over two thermal stress events, mesophotic reef <span class="hlt">bleaching</span> was driven by a <span class="hlt">bleaching</span> threshold that declines 0.26 °C every +10 m depth. Thus, the main premise of the deep reef refugia hypothesis that cooler environments are protective is incorrect; any increase in temperatures above the local mean warmest conditions can lead to thermal stress and <span class="hlt">bleaching</span>. Thus, relatively cooler temperatures can no longer be considered a de facto refugium for <span class="hlt">corals</span> and it is likely that many deeper <span class="hlt">coral</span> reefs are as vulnerable to climate change as shallow water reefs.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24486038','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24486038"><span>Community change and evidence for variable warm-water temperature adaptation of <span class="hlt">corals</span> in Northern Male Atoll, Maldives.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McClanahan, T R; Muthiga, N A</p> <p>2014-03-15</p> <p>This study provides a descriptive analysis of the North Male, Maldives seven years after the 1998 <span class="hlt">bleaching</span> disturbance to determine the state of the <span class="hlt">coral</span> community composition, the recruitment community, evidence for recovery, and adaptation to thermal stress. Overall, hard <span class="hlt">coral</span> cover recovered at a rate commonly reported in the literature but with high spatial variability and shifts in taxonomic composition. Massive Porites, Pavona, Synarea, and Goniopora were unusually common in both the recruit and adult communities. <span class="hlt">Coral</span> recruitment was low and some <span class="hlt">coral</span> taxa, namely Tubipora, Seriatopora, and Stylophora, were rarer than expected. A study of the <span class="hlt">bleaching</span> response to a thermal anomaly in 2005 indicated that some taxa, including Leptoria, Platygyra, Favites, Fungia, Hydnophora, and Galaxea astreata, <span class="hlt">bleached</span> as predicted while others, including Acropora, Pocillopora, branching Porites, Montipora, Stylophora, and Alveopora, <span class="hlt">bleached</span> less than predicted. This indicates variable-adaptation potentials among the taxa and considerable potential for ecological reorganization of the <span class="hlt">coral</span> community.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70120931','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70120931"><span><span class="hlt">Coral</span> microbiology</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rosenberg, Eugene; Kellogg, Christina A.; Rohwer, Forest</p> <p>2007-01-01</p> <p>In the last 30 years, there has been approximately a 30% loss of <span class="hlt">corals</span> worldwide, largely due to emerging diseases (Harvell et al., 2002, 2007; Hughes et al., 2003). <span class="hlt">Coral</span> microbiology is a new field, driven largely by a desire to understand the interactions between <span class="hlt">corals</span> and their symbiotic microorganisms and to use this knowledge to eventually prevent the spread of <span class="hlt">coral</span> diseases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70034587','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70034587"><span>Modeling regional <span class="hlt">coral</span> reef responses to global warming and changes in ocean chemistry: Caribbean case study</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Buddemeier, R.W.; Lane, D.R.; Martinich, J.A.</p> <p>2011-01-01</p> <p>Climatic change threatens the future of <span class="hlt">coral</span> reefs in the Caribbean and the important ecosystem services they provide. We used a simulation model [Combo ("<span class="hlt">COral</span> Mortality and <span class="hlt">Bleaching</span> Output")] to estimate future <span class="hlt">coral</span> cover in the part of the eastern Caribbean impacted by a massive <span class="hlt">coral</span> <span class="hlt">bleaching</span> event in 2005. Combo calculates impacts of future climate change on <span class="hlt">coral</span> reefs by combining impacts from long-term changes in average sea surface temperature (SST) and ocean acidification with impacts from episodic high temperature mortality (<span class="hlt">bleaching</span>) events. We used mortality and heat dose data from the 2005 <span class="hlt">bleaching</span> event to select historic temperature datasets, to use as a baseline for running Combo under different future climate scenarios and sets of assumptions. Results suggest a bleak future for <span class="hlt">coral</span> reefs in the eastern Caribbean. For three different emissions scenarios from the Intergovernmental Panel on Climate Change (IPCC; B1, A1B, and A1FI), <span class="hlt">coral</span> cover on most Caribbean reefs is projected to drop below 5% by the year 2035, if future mortality rates are equivalent to some of those observed in the 2005 event (50%). For a scenario where <span class="hlt">corals</span> gain an additional 1-1. 5??C of heat tolerance through a shift in the algae that live in the <span class="hlt">coral</span> tissue, <span class="hlt">coral</span> cover above 5% is prolonged until 2065. Additional impacts such as storms or anthropogenic damage could result in declines in <span class="hlt">coral</span> cover even faster than those projected here. These results suggest the need to identify and preserve the locations that are likely to have a higher resiliency to <span class="hlt">bleaching</span> to save as many remnant populations of <span class="hlt">corals</span> as possible in the face of projected wide-spread <span class="hlt">coral</span> loss. ?? 2011 The Author(s).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.B32D..07R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.B32D..07R"><span>Geochemical Records of <span class="hlt">Bleaching</span> Events and the Associated Stressors From the Great Barrier Reef</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roark, E. B.; McCulloch, M.; Ingram, B. L.; Marshall, J. F.</p> <p>2003-12-01</p> <p>The health of <span class="hlt">coral</span> reefs world-wide is increasingly threatened by a wide array of stressors. On the Great Barrier Reef (GBR) these stressors include increased sediment flux associated with land use changes, increased sea surface temperatures (SST) and salinity changes due to large floods, the latter two of which are factors in an increased number of <span class="hlt">bleaching</span> events. The ability to document long-term change in these stressors along with changes in the number of <span class="hlt">bleaching</span> events would help discern what are natural and anthropogenic changes in this ecosystem. Here we present results of an initial calibration effort aimed at identifying <span class="hlt">bleaching</span> events and the associated stressors using stable isotopic and trace element analysis in <span class="hlt">coral</span> cores. Three ˜15-year time series of geochemical measurements (δ 13C, δ 18O, and Sr/Ca) on Porites <span class="hlt">coral</span> cores obtained from Pandora Reef and the Keppel Islands on the GBR have been developed at near weekly resolution. Since the δ 13C of the <span class="hlt">coral</span> skeletal carbonate is known to be affected by both environmental factors (e.g. insolation and temperature) and physiological factors (e.g. photosynthesis, calcification, and the statues of the symbiotic relationship between <span class="hlt">corals</span> and zooxanthellae) it is the most promising proxy for reconstructing past <span class="hlt">bleaching</span> events. The first record (PAN-98) comes from a <span class="hlt">coral</span> head that had undergone <span class="hlt">bleaching</span> and died shortly after the large-scale <span class="hlt">bleaching</span> events on Pandora Reef in 1998. A second core (PAN-02) was collected from a living <span class="hlt">coral</span> within 10m of PAN-98 in 2002. Sr/Ca ratios in both cores tracked even the smallest details of an in situ SST record. The increase in SST that occurred three to four weeks prior to <span class="hlt">bleaching</span> was faithfully recorded by a similar decrease in the Sr/Ca ratio in PAN-98, indicating that calcification continued despite the high SST of 30-31° C. The δ 13C values decreased by about 5‰ , one week after the SST increase, and remained at this value for about 4</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=116343&keyword=technology+AND+productivity&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=90780959&CFTOKEN=57964282','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=116343&keyword=technology+AND+productivity&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=90780959&CFTOKEN=57964282"><span><span class="hlt">CORAL</span> CONDITION: HOW TO FATHOM THE DECLINE OF <span class="hlt">CORAL</span> REEF ECOSYSTEMS</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p><span class="hlt">Coral</span> reefs have experienced unprecedented levels of <span class="hlt">bleaching</span>, disease and mortality during the last three decades. The goal of EPA-ORD research is to identify the culpable stressors in different species, reefs and regions using integrated field and laboratory studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=allergy&pg=7&id=EJ727905','ERIC'); return false;" href="http://eric.ed.gov/?q=allergy&pg=7&id=EJ727905"><span><span class="hlt">Bleach</span> Neutralizes Mold Allergens</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Science Teacher, 2005</p> <p>2005-01-01</p> <p>Researchers at National Jewish Medical and Research Center have demonstrated that dilute <span class="hlt">bleach</span> not only kills common household mold, but may also neutralize the mold allergens that cause most mold-related health complaints. The study, published in the Journal of Allergy and Clinical Immunology, is the first to test the effect on allergic…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23858648','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23858648"><span>Historical thermal regimes define limits to <span class="hlt">coral</span> acclimatization.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Howells, Emily J; Berkelmans, Ray; van Oppen, Madeleine J H; Willis, Bette L; Bay, Line K</p> <p>2013-05-01</p> <p>Knowledge of the degree to which <span class="hlt">corals</span> undergo physiological acclimatization or genetic adaptation in response to changes in their thermal environment is crucial to the success of <span class="hlt">coral</span> reef conservation strategies. The potential of <span class="hlt">corals</span> to acclimatize to temperatures exceeding historical thermal regimes was investigated by reciprocal transplantation of Acropora millepora colonies between the warm central and cool southern regions of the Great Barrier Reef (GBR) for a duration of 14 months. Colony fragments retained at native sites remained healthy, whereas transplanted fragments, although healthy over initial months when temperatures remained within native thermal regimes, subsequently <span class="hlt">bleached</span> and suffered mortality during seasonal temperature extremes. <span class="hlt">Corals</span> hosting Symbiodinium D transplanted to the southern GBR <span class="hlt">bleached</span> in winter and the majority suffered whole (40%; n=20 colonies) or partial (50%) mortality at temperatures 1.1 degrees C below their 15-year native minimum. In contrast, <span class="hlt">corals</span> hosting Symbiodinium C2 transplanted to the central GBR <span class="hlt">bleached</span> in summer and suffered whole (50%; n=10 colonies) or partial (42%) mortality at temperatures 2.5 degrees C above their 15-year native maximum. During summer <span class="hlt">bleaching</span>, the dominant Symbiodinium type changed from C2 to D within <span class="hlt">corals</span> transplanted to the central GBR. <span class="hlt">Corals</span> transplanted to the cooler, southern GBR grew 74-80% slower than <span class="hlt">corals</span> at their native site, and only 50% of surviving colonies reproduced, at least partially because of cold water <span class="hlt">bleaching</span> of transplants. Despite the absence of any visual signs of stress, <span class="hlt">corals</span> transplanted to the warmer, central GBR grew 52-59% more slowly than <span class="hlt">corals</span> at their native site before the summer <span class="hlt">bleaching</span> (i.e., from autumn to spring). Allocation of energy to initial acclimatization or reproduction may explain this pattern, as the majority (65%) of transplants reproduced one month earlier than portions of the same colonies retained at the southern</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMOS12A..04E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS12A..04E"><span><span class="hlt">Coral</span> Reef Remote Sensing: Helping Managers Protect Reefs in a Changing Climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eakin, C.; Liu, G.; Li, J.; Muller-Karger, F. E.; Heron, S. F.; Gledhill, D. K.; Christensen, T.; Rauenzahn, J.; Morgan, J.; Parker, B. A.; Skirving, W. J.; Nim, C.; Burgess, T.; Strong, A. E.</p> <p>2010-12-01</p> <p>Climate change and ocean acidification are already having severe impacts on <span class="hlt">coral</span> reef ecosystems. Warming oceans have caused <span class="hlt">corals</span> to <span class="hlt">bleach</span>, or expel their symbiotic algae (zooxanthellae) with alarming frequency and severity and have contributed to a rise in <span class="hlt">coral</span> infectious diseases. Ocean acidification is reducing the availability of carbonate ions needed by <span class="hlt">corals</span> and many other marine organisms to build structural components like skeletons and shells and may already be slowing the <span class="hlt">coral</span> growth. These two impacts are already killing <span class="hlt">corals</span> and slowing reef growth, reducing biodiversity and the structure needed to provide crucial ecosystem services. NOAA’s <span class="hlt">Coral</span> Reef Watch (CRW) uses a combination of satellite data, in situ observations, and models to provide <span class="hlt">coral</span> reef managers, scientists, and others with information needed to monitor threats to <span class="hlt">coral</span> reefs. The advance notice provided by remote sensing and models allows resource managers to protect <span class="hlt">corals</span>, <span class="hlt">coral</span> reefs, and the services they provide, although managers often encounter barriers to implementation of adaptation strategies. This talk will focus on application of NOAA’s satellite and model-based tools that monitor the risk of mass <span class="hlt">coral</span> <span class="hlt">bleaching</span> on a global scale, ocean acidification in the Caribbean, and <span class="hlt">coral</span> disease outbreaks in selected regions, as well as CRW work to train managers in their use, and barriers to taking action to adapt to climate change. As both anthropogenic CO2 and temperatures will continue to rise, local actions to protect reefs are becoming even more important.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUSM...U31A11K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUSM...U31A11K"><span><span class="hlt">Coral</span> Reef Remote Sensing Database and Monitoring of <span class="hlt">Coral</span> Reefs by ASTER</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kayanne, H.; Matsunaga, T.; Kanbara, H.; Kato, M.</p> <p>2001-05-01</p> <p><span class="hlt">Coral</span> reefs in the world are under the crisis of degradation both by increasing human activities in coastal zone and by the global changes. All the factors of the global change scenario would bring serious impact on <span class="hlt">coral</span> reefs. Increase in CO2 suppress calcification in <span class="hlt">coral</span> reefs. The world-wide <span class="hlt">bleaching</span> event in 1997-1998 was supposed to be at least partly resulted from global warming. <span class="hlt">Coral</span> reefs would submerge by sea level rise in this century. To conserve and manage <span class="hlt">coral</span> reefs against these threats, monitoring of <span class="hlt">coral</span> reef by satellite remote sensing is important. ASTER has provided effective data for mapping <span class="hlt">coral</span> reef landforms and benthic communities. The most basic geomorphological and ecological zonation was successfully classified using ASTER data. For example, <span class="hlt">coral</span> reef flat with its zonation of algai rim, rubble bank, back reef was clearly identified by ASTER by decision tree method and bottom index using VNIR bands data. For the basis of effective monitoring of <span class="hlt">coral</span> reefs, we have constructed <span class="hlt">coral</span> reef remote sensing database, which contains more than 1,100,000 data. Tropical and subtropical oceans (40N-40S) were gridded by 0.5 x 0.5 degrees and the grids with <span class="hlt">coral</span> reefs were identified. The grids with <span class="hlt">coral</span> reefs correspond to path/rows of the satellite (MOS1, JERS-1, ADEOS, LANDSAT, SPOT and TERRA) and basic information (existence of data, satellite and sensor, path/row, lat/log, aquisition date, cloud cover, type of <span class="hlt">coral</span> reef) of so-far obtained satellite data until 2000 was input in the database. Status of data aquisition at specific <span class="hlt">coral</span> reefs can be listed up by this database.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMPP43B1287K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMPP43B1287K"><span>Lipid biomarkers of thermal stress in scleractinian <span class="hlt">corals</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kneeland, J. M.; Hughen, K.; Cervino, J.; Eglinton, T. I.; Bartels, E.</p> <p>2007-12-01</p> <p>Lipid content and fatty acid profiles of <span class="hlt">corals</span> and their symbiotic dinoflagellates are known to vary in response to heat stress and <span class="hlt">bleaching</span>. To develop lipid biomarkers of heat stress and <span class="hlt">bleaching</span> response in scleractinian <span class="hlt">corals</span>, clones of Symbiodinium algae of clade subtypes C1 and D1 were cultured under a range of temperatures. The predominant lipids produced are palmitic (C16) and stearic (C18) saturated fatty acids and their unsaturated analogs. Other important compounds included a C22 penta-unsaturated fatty acid, which is thought to be a specific dinoflagellate marker, and a variety of sterols. Analysis of lipids extracted from <span class="hlt">coral</span> skeleton indicated that palmitic and stearic acids were the most abundant compounds. The amount of unsaturated C16 and C18 fatty acids in <span class="hlt">coral</span> skeleton relative to the saturated versions of those acids was much lower in <span class="hlt">coral</span> skeleton than in the zooxanthellae tissue. This could indicate the incorporation of lipids from outside the <span class="hlt">coral</span> host-symbiont system into the <span class="hlt">coral</span> aragonite, or it could reflect diagenesis. A comparison between the lipids found in cloned zooxanthellae, <span class="hlt">coral</span> tissue, and aragonitic skeleton will be presented to assess the usefulness of lipid biomarkers as indicators of temperature stress on <span class="hlt">corals</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009CorRe..28....3W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009CorRe..28....3W"><span>Maintenance of fish diversity on disturbed <span class="hlt">coral</span> reefs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wilson, S. K.; Dolman, A. M.; Cheal, A. J.; Emslie, M. J.; Pratchett, M. S.; Sweatman, H. P. A.</p> <p>2009-03-01</p> <p>Habitat perturbations play a major role in shaping community structure; however, the elements of disturbance-related habitat change that affect diversity are not always apparent. This study examined the effects of habitat disturbances on species richness of <span class="hlt">coral</span> reef fish assemblages using annual surveys of habitat and 210 fish species from 10 reefs on the Great Barrier Reef (GBR). Over a period of 11 years, major disturbances, including localised outbreaks of crown-of-thorns sea star ( Acanthaster planci), severe storms or <span class="hlt">coral</span> <span class="hlt">bleaching</span>, resulted in <span class="hlt">coral</span> decline of 46-96% in all the 10 reefs. Despite declines in <span class="hlt">coral</span> cover, structural complexity of the reef framework was retained on five and species richness of <span class="hlt">coral</span> reef fishes maintained on nine of the disturbed reefs. Extensive loss of <span class="hlt">coral</span> resulted in localised declines of highly specialised <span class="hlt">coral</span>-dependent species, but this loss of diversity was more than compensated for by increases in the number of species that feed on the epilithic algal matrix (EAM). A unimodal relationship between areal <span class="hlt">coral</span> cover and species richness indicated species richness was greatest at approximately 20% <span class="hlt">coral</span> cover declining by 3-4 species (6-8% of average richness) at higher and lower <span class="hlt">coral</span> cover. Results revealed that declines in <span class="hlt">coral</span> cover on reefs may have limited short-term impact on the diversity of <span class="hlt">coral</span> reef fishes, though there may be fundamental changes in the community structure of fishes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JJSMS..23..2.9Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JJSMS..23..2.9Y"><span>The Construction of a <span class="hlt">Coral</span> Implantation Base and the Proof Experiment by Electrodeposition Method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoshitake, Masami; Nojima, Satoshi; Tokuyama, Hidekazu; Haraguchi, Satoru; Kadomoto, Yukio; Yoshida, Kazuo</p> <p></p> <p>In recent years, we are facing a decline of <span class="hlt">coral</span> reefs by <span class="hlt">bleaching</span> and death of <span class="hlt">coral</span> colonies, which is casued by rising of ocean temperatures presumably due to global warming and pollution due to human activity. It is our urgent issue to protect and reproduce <span class="hlt">coral</span> reefs in a global scale. We propose an electrodeposition method using calcium and magnesium contained in natural seawater as a effective and way to revive <span class="hlt">coral</span> reefs, because a product of electrodeposition characterized by porous texture provides suitable holes for implantation of <span class="hlt">coral</span> larvae. We expect that the method creates a diverse <span class="hlt">coral</span> reefs community similar to natural one comparing with other growth method. Since 2008, we have conducted <span class="hlt">coral</span> growth experiments using electrodeposition in Yoronjima. As a result, Acropora sp., Porites sp. and Pocillopora sp. are observed, such as implantation of several types of <span class="hlt">coral</span> larvae, and confirmed a growth of <span class="hlt">coral</span> larvae.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014CorRe..33..891B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014CorRe..33..891B"><span>Local extinction of a <span class="hlt">coral</span> reef fish explained by inflexible prey choice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brooker, R. M.; Munday, P. L.; Brandl, S. J.; Jones, G. P.</p> <p>2014-12-01</p> <p>While global extinctions of marine species are infrequent, local extinctions are becoming common. However, the role of habitat degradation and resource specialisation in explaining local extinction is unknown. On <span class="hlt">coral</span> reefs, <span class="hlt">coral</span> <span class="hlt">bleaching</span> is an increasingly frequent cause of <span class="hlt">coral</span> mortality that can result in dramatic changes to <span class="hlt">coral</span> community composition. <span class="hlt">Coral</span>-associated fishes are often specialised on a limited suite of <span class="hlt">coral</span> species and are therefore sensitive to these changes. This study documents the local extinction of a corallivorous reef fish, Oxymonacanthus longirostris, following a mass <span class="hlt">bleaching</span> event that altered the species composition of associated <span class="hlt">coral</span> communities. Local extinction only occurred on reefs that also completely lost a key prey species, Acropora millepora, even though <span class="hlt">coral</span> cover remained high. In an experimental test, fish continued to select <span class="hlt">bleached</span> A. millepora over the healthy, but less-preferred prey species that resisted <span class="hlt">bleaching</span>. These results suggest that behavioural inflexibility may limit the ability of specialists to cope with even subtle changes to resource availability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=161405&keyword=Biosphere+AND+2&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78719276&CFTOKEN=91248599','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=161405&keyword=Biosphere+AND+2&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78719276&CFTOKEN=91248599"><span>THE IMPACT OF CDOM PHOTOBLEACHING ON UV ATTENUATION NEAR <span class="hlt">CORAL</span> REEFS IN THE FLORIDA KEYS</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>We have investigated how the loss of chromophoric dissolved organic matter (CDOM) in the water column due to photobleaching allows for increased penetration of UV radiation near <span class="hlt">coral</span> reefs in the Florida Keys. Extended exposure to UV may contribute to <span class="hlt">coral</span> <span class="hlt">bleaching</span> episodes. C...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=116345&keyword=global+AND+warming+AND+coral+AND+reefs&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=89695052&CFTOKEN=69759107','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=116345&keyword=global+AND+warming+AND+coral+AND+reefs&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=89695052&CFTOKEN=69759107"><span>MEETING AT PORTLAND, OR: <span class="hlt">CORAL</span> RESPONSES TO CLIMATE AND LAND USE CHANGES</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p><span class="hlt">Coral</span> reefs in the Florida Keys have been surveyed for occurrence of <span class="hlt">bleaching</span> and disease, and additional indicators are being applied across the Keys to characterize the status of <span class="hlt">coral</span> condition. Studies on cultured symbiotic algae have demonstrated combined effects of tempera...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70158629','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70158629"><span>Life on the edge: <span class="hlt">corals</span> in mangroves and climate change</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rogers, Caroline S.; Herlan, James J.</p> <p>2012-01-01</p> <p><span class="hlt">Coral</span> diseases have played a major role in the degradation of <span class="hlt">coral</span> reefs in the Caribbean, including those in the US Virgin Islands (USVI). In 2005, <span class="hlt">bleaching</span> affected reefs throughout the Caribbean, and was especially severe on USVI reefs. Some <span class="hlt">corals</span> began to regain their color as water temperatures cooled, but an outbreak of disease (primarily white plague) led to losses of over 60% of the total live <span class="hlt">coral</span> cover. Montastraea annularis, the most abundant <span class="hlt">coral</span>, was disproportionately affected, and decreased in relative abundance. The threatened species Acropora palmata <span class="hlt">bleached</span> for the first time on record in the USVI but suffered less <span class="hlt">bleaching</span> and less mortality from disease than M. annularis. Acropora palmata and M. annularis are the two most significant species in the USVI because of their structural role in the architecture of the reefs, the large size of their colonies, and their complex morphology. The future of the USVI reefs depends largely on their fate. Acropora palmata is more likely to recover than M. annularis for many reasons, including its faster growth rate, and its lower vulnerability to <span class="hlt">bleaching</span> and disease.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3511300','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3511300"><span><span class="hlt">Coral</span> Thermal Tolerance: Tuning Gene Expression to Resist Thermal Stress</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bellantuono, Anthony J.; Granados-Cifuentes, Camila; Miller, David J.; Hoegh-Guldberg, Ove; Rodriguez-Lanetty, Mauricio</p> <p>2012-01-01</p> <p>The acclimatization capacity of <span class="hlt">corals</span> is a critical consideration in the persistence of <span class="hlt">coral</span> reefs under stresses imposed by global climate change. The stress history of <span class="hlt">corals</span> plays a role in subsequent response to heat stress, but the transcriptomic changes associated with these plastic changes have not been previously explored. In order to identify host transcriptomic changes associated with acquired thermal tolerance in the scleractinian <span class="hlt">coral</span> Acropora millepora, <span class="hlt">corals</span> preconditioned to a sub-lethal temperature of 3°C below <span class="hlt">bleaching</span> threshold temperature were compared to both non-preconditioned <span class="hlt">corals</span> and untreated controls using a cDNA microarray platform. After eight days of hyperthermal challenge, conditions under which non-preconditioned <span class="hlt">corals</span> <span class="hlt">bleached</span> and preconditioned <span class="hlt">corals</span> (thermal-tolerant) maintained Symbiodinium density, a clear differentiation in the transcriptional profiles was revealed among the condition examined. Among these changes, nine differentially expressed genes separated preconditioned <span class="hlt">corals</span> from non-preconditioned <span class="hlt">corals</span>, with 42 genes differentially expressed between control and preconditioned treatments, and 70 genes between non-preconditioned <span class="hlt">corals</span> and controls. Differentially expressed genes included components of an apoptotic signaling cascade, which suggest the inhibition of apoptosis in preconditioned <span class="hlt">corals</span>. Additionally, lectins and genes involved in response to oxidative stress were also detected. One dominant pattern was the apparent tuning of gene expression observed between preconditioned and non-preconditioned treatments; that is, differences in expression magnitude were more apparent than differences in the identity of genes differentially expressed. Our work revealed a transcriptomic signature underlying the tolerance associated with <span class="hlt">coral</span> thermal history, and suggests that understanding the molecular mechanisms behind physiological acclimatization would be critical for the modeling of reefs in impending climate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23226355','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23226355"><span><span class="hlt">Coral</span> thermal tolerance: tuning gene expression to resist thermal stress.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bellantuono, Anthony J; Granados-Cifuentes, Camila; Miller, David J; Hoegh-Guldberg, Ove; Rodriguez-Lanetty, Mauricio</p> <p>2012-01-01</p> <p>The acclimatization capacity of <span class="hlt">corals</span> is a critical consideration in the persistence of <span class="hlt">coral</span> reefs under stresses imposed by global climate change. The stress history of <span class="hlt">corals</span> plays a role in subsequent response to heat stress, but the transcriptomic changes associated with these plastic changes have not been previously explored. In order to identify host transcriptomic changes associated with acquired thermal tolerance in the scleractinian <span class="hlt">coral</span> Acropora millepora, <span class="hlt">corals</span> preconditioned to a sub-lethal temperature of 3°C below <span class="hlt">bleaching</span> threshold temperature were compared to both non-preconditioned <span class="hlt">corals</span> and untreated controls using a cDNA microarray platform. After eight days of hyperthermal challenge, conditions under which non-preconditioned <span class="hlt">corals</span> <span class="hlt">bleached</span> and preconditioned <span class="hlt">corals</span> (thermal-tolerant) maintained Symbiodinium density, a clear differentiation in the transcriptional profiles was revealed among the condition examined. Among these changes, nine differentially expressed genes separated preconditioned <span class="hlt">corals</span> from non-preconditioned <span class="hlt">corals</span>, with 42 genes differentially expressed between control and preconditioned treatments, and 70 genes between non-preconditioned <span class="hlt">corals</span> and controls. Differentially expressed genes included components of an apoptotic signaling cascade, which suggest the inhibition of apoptosis in preconditioned <span class="hlt">corals</span>. Additionally, lectins and genes involved in response to oxidative stress were also detected. One dominant pattern was the apparent tuning of gene expression observed between preconditioned and non-preconditioned treatments; that is, differences in expression magnitude were more apparent than differences in the identity of genes differentially expressed. Our work revealed a transcriptomic signature underlying the tolerance associated with <span class="hlt">coral</span> thermal history, and suggests that understanding the molecular mechanisms behind physiological acclimatization would be critical for the modeling of reefs in impending climate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3240979','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3240979"><span>Defining the tipping point. A complex cellular life/death balance in <span class="hlt">corals</span> in response to stress</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>T. D., Ainsworth; K., Wasmund; L., Ukani; F., Seneca; D., Yellowlees; D., Miller; W., Leggat</p> <p>2011-01-01</p> <p>Apoptotic cell death has been implicated in <span class="hlt">coral</span> <span class="hlt">bleaching</span> but the molecules involved and the mechanisms by which apoptosis is regulated are only now being identified. In contrast the mechanisms underlying apoptosis in higher animals are relatively well understood. To better understand the response of <span class="hlt">corals</span> to thermal stress, the expression of <span class="hlt">coral</span> homologs of six key regulators of apoptosis was studied in Acropora aspera under conditions simulating those of a mass <span class="hlt">bleaching</span> event. Significant changes in expression were detected between the daily minimum and maximum temperatures. Maximum daily temperatures from as low as 3°C below the <span class="hlt">bleaching</span> threshold resulted in significant changes in both pro- and anti-apoptotic gene expression. The results suggest that the control of apoptosis is highly complex in this eukaryote-eukaryote endosymbiosis and that apoptotic cell death cascades potentially play key roles tipping the cellular life/death balance during environmental stress prior to the onset of <span class="hlt">coral</span> <span class="hlt">bleaching</span>. PMID:22355675</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4262390','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4262390"><span>Moderate Thermal Stress Causes Active and Immediate Expulsion of Photosynthetically Damaged Zooxanthellae (Symbiodinium) from <span class="hlt">Corals</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Fujise, Lisa; Yamashita, Hiroshi; Suzuki, Go; Sasaki, Kengo; Liao, Lawrence M.; Koike, Kazuhiko</p> <p>2014-01-01</p> <p>The foundation of <span class="hlt">coral</span> reef biology is the symbiosis between <span class="hlt">corals</span> and zooxanthellae (dinoflagellate genus Symbiodinium). Recently, <span class="hlt">coral</span> <span class="hlt">bleaching</span>, which often results in mass mortality of <span class="hlt">corals</span> and the collapse of <span class="hlt">coral</span> reef ecosystems, has become an important issue around the world as <span class="hlt">coral</span> reefs decrease in number year after year. To understand the mechanisms underlying <span class="hlt">coral</span> <span class="hlt">bleaching</span>, we maintained two species of scleractinian <span class="hlt">corals</span> (Acroporidae) in aquaria under non-thermal stress (27°C) and moderate thermal stress conditions (30°C), and we compared the numbers and conditions of the expelled Symbiodinium from these <span class="hlt">corals</span>. Under non-thermal stress conditions <span class="hlt">corals</span> actively expel a degraded form of Symbiodinium, which are thought to be digested by their host <span class="hlt">coral</span>. This response was also observed at 30°C. However, while the expulsion rates of Symbiodinium cells remained constant, the proportion of degraded cells significantly increased at 30°C. This result indicates that <span class="hlt">corals</span> more actively digest and expel damaged Symbiodinium under thermal stress conditions, likely as a mechanism for coping with environmental change. However, the increase in digested Symbiodinium expulsion under thermal stress may not fully keep up with accumulation of the damaged cells. There are more photosynthetically damaged Symbiodinium upon prolonged exposure to thermal stress, and <span class="hlt">corals</span> release them without digestion to prevent their accumulation. This response may be an adaptive strategy to moderate stress to ensure survival, but the accumulation of damaged Symbiodinium, which causes subsequent <span class="hlt">coral</span> deterioration, may occur when the response cannot cope with the magnitude or duration of environmental stress, and this might be a possible mechanism underlying <span class="hlt">coral</span> <span class="hlt">bleaching</span> during prolonged moderate thermal stress. PMID:25493938</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25493938','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25493938"><span>Moderate Thermal Stress Causes Active and Immediate Expulsion of Photosynthetically Damaged Zooxanthellae (Symbiodinium) from <span class="hlt">Corals</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fujise, Lisa; Yamashita, Hiroshi; Suzuki, Go; Sasaki, Kengo; Liao, Lawrence M; Koike, Kazuhiko</p> <p>2014-01-01</p> <p>The foundation of <span class="hlt">coral</span> reef biology is the symbiosis between <span class="hlt">corals</span> and zooxanthellae (dinoflagellate genus Symbiodinium). Recently, <span class="hlt">coral</span> <span class="hlt">bleaching</span>, which often results in mass mortality of <span class="hlt">corals</span> and the collapse of <span class="hlt">coral</span> reef ecosystems, has become an important issue around the world as <span class="hlt">coral</span> reefs decrease in number year after year. To understand the mechanisms underlying <span class="hlt">coral</span> <span class="hlt">bleaching</span>, we maintained two species of scleractinian <span class="hlt">corals</span> (Acroporidae) in aquaria under non-thermal stress (27°C) and moderate thermal stress conditions (30°C), and we compared the numbers and conditions of the expelled Symbiodinium from these <span class="hlt">corals</span>. Under non-thermal stress conditions <span class="hlt">corals</span> actively expel a degraded form of Symbiodinium, which are thought to be digested by their host <span class="hlt">coral</span>. This response was also observed at 30°C. However, while the expulsion rates of Symbiodinium cells remained constant, the proportion of degraded cells significantly increased at 30°C. This result indicates that <span class="hlt">corals</span> more actively digest and expel damaged Symbiodinium under thermal stress conditions, likely as a mechanism for coping with environmental change. However, the increase in digested Symbiodinium expulsion under thermal stress may not fully keep up with accumulation of the damaged cells. There are more photosynthetically damaged Symbiodinium upon prolonged exposure to thermal stress, and <span class="hlt">corals</span> release them without digestion to prevent their accumulation. This response may be an adaptive strategy to moderate stress to ensure survival, but the accumulation of damaged Symbiodinium, which causes subsequent <span class="hlt">coral</span> deterioration, may occur when the response cannot cope with the magnitude or duration of environmental stress, and this might be a possible mechanism underlying <span class="hlt">coral</span> <span class="hlt">bleaching</span> during prolonged moderate thermal stress.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000Natur.408..850S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000Natur.408..850S"><span>Fluorescent pigments in <span class="hlt">corals</span> are photoprotective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salih, Anya; Larkum, Anthony; Cox, Guy; Kühl, Michael; Hoegh-Guldberg, Ove</p> <p>2000-12-01</p> <p>All reef-forming <span class="hlt">corals</span> depend on the photosynthesis performed by their algal symbiont, and such <span class="hlt">corals</span> are therefore restricted to the photic zone. The intensity of light in this zone declines over several orders of magnitude-from high and damaging levels at the surface to extreme shade conditions at the lower limit. The ability of <span class="hlt">corals</span> to tolerate this range implies effective mechanisms for light acclimation and adaptation. Here we show that the fluorescent pigments (FPs) of <span class="hlt">corals</span> provide a photobiological system for regulating the light environment of <span class="hlt">coral</span> host tissue. Previous studies have suggested that under low light, FPs may enhance light availability. We now report that in excessive sunlight FPs are photoprotective; they achieve this by dissipating excess energy at wavelengths of low photosynthetic activity, as well as by reflecting of visible and infrared light by FP-containing chromatophores. We also show that FPs enhance the resistance to mass <span class="hlt">bleaching</span> of <span class="hlt">corals</span> during periods of heat stress, which has implications for the effect of environmental stress on the diversity of reef-building <span class="hlt">corals</span>, such as enhanced survival of a broad range of <span class="hlt">corals</span> allowing maintenance of habitat diversity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4716698','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4716698"><span>Can a <span class="hlt">bleaching</span> toothpaste containing Blue Covarine demonstrate the same <span class="hlt">bleaching</span> as conventional techniques? An in vitro, randomized and blinded study</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>DANTAS, Andréa Abi Rached; BORTOLATTO, Janaina Freitas; RONCOLATO, Ávery; MERCHAN, Hugo; FLOROS, Michael Christopher; KUGA, Milton Carlos; de OLIVEIRA, Osmir Batista</p> <p>2015-01-01</p> <p><span class="hlt">ABSTRACT</span> Objective The purpose of this in vitro study was to compare the efficacy of a <span class="hlt">bleaching</span> toothpaste containing Blue Covarine vs. conventional tooth <span class="hlt">bleaching</span> techniques using peroxides (both in-office and at-home). Material and Methods Samples were randomly distributed into five experimental groups (n=15): C - Control; BC – <span class="hlt">Bleaching</span> toothpaste containing Blue Covarine; WBC – <span class="hlt">Bleaching</span> toothpaste without Blue Covarine; HP35 - In-office <span class="hlt">bleaching</span> using 35% hydrogen peroxide; and CP10 – At-home <span class="hlt">bleaching</span> with 10% carbamide peroxide. The dental <span class="hlt">bleaching</span> efficacy was determined by the color difference (ΔE), luminosity (ΔL), green-red axis (Δa), and blue-yellow axis (Δb). The CIELab coordinates were recorded with reflectance spectroscopy at different times: T0 - baseline, T1 – immediately after <span class="hlt">bleaching</span>, T2 - 7 days, T3 - 14 days, and T4 - 21 days after the end of treatments. Data were analyzed by a repeated measures mixed ANOVA and post hoc Bonferroni test, with a significance level of 5%. Results No significant differences were found between the treatment groups C, BC, and WBC. The groups HP35 and CP10 showed significantly higher whitening efficacy than groups C, BC, and WBC. Conclusions There were no significant differences in the whitening efficacy between a Blue Covarine containing toothpaste, a standard whitening toothpaste, and a control. Neither of the whitening toothpastes tested were as effective as in-office or at-home <span class="hlt">bleaching</span> treatments. PMID:26814462</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70137561','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70137561"><span>Diverse <span class="hlt">coral</span> communities in mangrove habitats suggest a novel refuge from climate change</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Yates, Kimberly K.; Rogers, Caroline S.; Herlan, James J.; Brooks, Gregg R.; Smiley, Nathan A.; Larson, Rebekka A.</p> <p>2014-01-01</p> <p>Over 30 species of scleractinian <span class="hlt">corals</span> were growing in association with mangroves. <span class="hlt">Corals</span> were thriving in low-light (more than 70% attenuation of incident PAR) from mangrove shading and at higher temperatures than nearby reef tract <span class="hlt">corals</span>. A higher percentage of C. natans colonies were living shaded by mangroves, and no shaded colonies were <span class="hlt">bleached</span>. Fewer D. labyrinthiformis colonies were shaded by mangroves, however more unshaded colonies were <span class="hlt">bleached</span>. A combination of substrate and habitat heterogeneity, proximity of different habitat types, hydrographic conditions, and biological influences on seawater chemistry generate chemical conditions that buffer against ocean acidification. This previously undocumented refuge for <span class="hlt">corals</span> provides evidence for adaptation of coastal organisms and ecosystem transition due to recent climate change. Identifying and protecting other natural, non-reef <span class="hlt">coral</span> refuges is critical for sustaining <span class="hlt">corals</span> and other reef species into the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5635165','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5635165"><span>Ozone <span class="hlt">bleaching</span> of recycled paper</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Muguet, M.; Kogan, J. )</p> <p>1993-11-01</p> <p>Chlorinated <span class="hlt">bleaching</span> chemicals, notably chlorine and hypochlorite, are still being used to <span class="hlt">bleach</span> deinked, woodfree pulps. Increasing environmental concern about the use of these chemicals--coupled with the industry's efforts to increase the use of recycled fibers--highlight the need to develop better techniques for producing high-quality deinked pulp. Results presented in this report suggest that deinked fibers can be treated with ozone followed by a peroxide <span class="hlt">bleaching</span> stage to produce a high-quality pulp.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B21C0435B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B21C0435B"><span>Lithifying Microbes Associated to <span class="hlt">Coral</span> Rubbles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beltran, Y.</p> <p>2015-12-01</p> <p>Microbial communities taking part in calcium carbonate lithification processes are particularly relevant to <span class="hlt">coral</span> reef formation in as much as this lithification allows the stabilization of secondary reef structure. This second framework promotes long-term permanence of the reef, favoring the establishment of macro-reef builders, including <span class="hlt">corals</span>. The reef-bacterial crusts formed by microbial communities are composed of magnesium calcite. Although prokaryotes are not proper calcifiers, carbonate precipitation can be induced by their metabolic activity and EPS production. <span class="hlt">Coral</span> reefs are rapidly declining due to several variables associated to environmental change. Specifically in the Caribbean, stony <span class="hlt">coral</span> Acropora palmata have suffered damage due to diseases, <span class="hlt">bleaching</span> and storms. Some reports show that in highly disturbed areas wide ridges of reef rubbles are formed by biological and physical lithification. In this study we explore microbial diversity associated to lithified rubbles left after the great decline of reef-building A. palmata.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5310043','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5310043"><span>Drivers and predictions of <span class="hlt">coral</span> reef carbonate budget trajectories</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Graham, Nicholas A. J.; Jennings, Simon; Perry, Chris T.</p> <p>2017-01-01</p> <p>Climate change is one of the greatest threats to the long-term maintenance of <span class="hlt">coral</span>-dominated tropical ecosystems, and has received considerable attention over the past two decades. <span class="hlt">Coral</span> <span class="hlt">bleaching</span> and associated mortality events, which are predicted to become more frequent and intense, can alter the balance of different elements that are responsible for <span class="hlt">coral</span> reef growth and maintenance. The geomorphic impacts of <span class="hlt">coral</span> mass mortality have received relatively little attention, particularly questions concerning temporal recovery of reef carbonate production and the factors that promote resilience of reef growth potential. Here, we track the biological carbonate budgets of inner Seychelles reefs from 1994 to 2014, spanning the 1998 global <span class="hlt">bleaching</span> event when these reefs lost more than 90% of <span class="hlt">coral</span> cover. All 21 reefs had positive budgets in 1994, but in 2005 budgets were predominantly negative. By 2014, carbonate budgets on seven reefs were comparable with 1994, but on all reefs where an ecological regime shift to macroalgal dominance occurred, budgets remained negative through 2014. Reefs with higher massive <span class="hlt">coral</span> cover, lower macroalgae cover and lower excavating parrotfish biomass in 1994 were more likely to have positive budgets post-<span class="hlt">bleaching</span>. If mortality of <span class="hlt">corals</span> from the 2016 <span class="hlt">bleaching</span> event is as severe as that of 1998, our predictions based on past trends would suggest that six of eight reefs with positive budgets in 2014 would still have positive budgets by 2030. Our results highlight that reef accretion and framework maintenance cannot be assumed from the ecological state alone, and that managers should focus on conserving aspects of <span class="hlt">coral</span> reefs that support resilient carbonate budgets. PMID:28123092</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28123092','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28123092"><span>Drivers and predictions of <span class="hlt">coral</span> reef carbonate budget trajectories.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Januchowski-Hartley, Fraser A; Graham, Nicholas A J; Wilson, Shaun K; Jennings, Simon; Perry, Chris T</p> <p>2017-01-25</p> <p>Climate change is one of the greatest threats to the long-term maintenance of <span class="hlt">coral</span>-dominated tropical ecosystems, and has received considerable attention over the past two decades. <span class="hlt">Coral</span> <span class="hlt">bleaching</span> and associated mortality events, which are predicted to become more frequent and intense, can alter the balance of different elements that are responsible for <span class="hlt">coral</span> reef growth and maintenance. The geomorphic impacts of <span class="hlt">coral</span> mass mortality have received relatively little attention, particularly questions concerning temporal recovery of reef carbonate production and the factors that promote resilience of reef growth potential. Here, we track the biological carbonate budgets of inner Seychelles reefs from 1994 to 2014, spanning the 1998 global <span class="hlt">bleaching</span> event when these reefs lost more than 90% of <span class="hlt">coral</span> cover. All 21 reefs had positive budgets in 1994, but in 2005 budgets were predominantly negative. By 2014, carbonate budgets on seven reefs were comparable with 1994, but on all reefs where an ecological regime shift to macroalgal dominance occurred, budgets remained negative through 2014. Reefs with higher massive <span class="hlt">coral</span> cover, lower macroalgae cover and lower excavating parrotfish biomass in 1994 were more likely to have positive budgets post-<span class="hlt">bleaching</span>. If mortality of <span class="hlt">corals</span> from the 2016 <span class="hlt">bleaching</span> event is as severe as that of 1998, our predictions based on past trends would suggest that six of eight reefs with positive budgets in 2014 would still have positive budgets by 2030. Our results highlight that reef accretion and framework maintenance cannot be assumed from the ecological state alone, and that managers should focus on conserving aspects of <span class="hlt">coral</span> reefs that support resilient carbonate budgets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014CorRe..33..449C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014CorRe..33..449C"><span>Bottlenecks to <span class="hlt">coral</span> recovery in the Seychelles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chong-Seng, K. M.; Graham, N. A. J.; Pratchett, M. S.</p> <p>2014-06-01</p> <p>Processes that affect recovery of <span class="hlt">coral</span> assemblages require investigation because <span class="hlt">coral</span> reefs are experiencing a diverse array of more frequent disturbances. Potential bottlenecks to <span class="hlt">coral</span> recovery include limited larval supply, low rates of settlement, and high mortality of new recruits or juvenile <span class="hlt">corals</span>. We investigated spatial variation in local abundance of scleractinian <span class="hlt">corals</span> in the Seychelles at three distinct life history stages (recruits, juveniles, and adults) on reefs with differing benthic conditions. Following widespread <span class="hlt">coral</span> loss due to the 1998 <span class="hlt">bleaching</span> event, some reefs are recovering (i.e., relatively high scleractinian <span class="hlt">coral</span> cover: `<span class="hlt">coral</span>-dominated'), some reefs have low cover of living macrobenthos and unconsolidated rubble substrates (`rubble-dominated'), and some reefs have high cover of macroalgae (`macroalgal-dominated'). Rates of <span class="hlt">coral</span> recruitment to artificial settlement tiles were similar across all reef conditions, suggesting that larval supply does not explain differential <span class="hlt">coral</span> recovery across the three reef types. However, acroporid recruits were absent on macroalgal-dominated reefs (0.0 ± 0.0 recruits tile-1) in comparison to <span class="hlt">coral</span>-dominated reefs (5.2 ± 1.6 recruits tile-1). Juvenile <span class="hlt">coral</span> colony density was significantly lower on macroalgal-dominated reefs (2.4 ± 1.1 colonies m-2), compared to <span class="hlt">coral</span>-dominated reefs (16.8 ± 2.4 m-2) and rubble-dominated reefs (33.1 ± 7.3 m-2), suggesting that macroalgal-dominated reefs have either a bottleneck to successful settlement on the natural substrates or a high post-settlement mortality bottleneck. Rubble-dominated reefs had very low cover of adult <span class="hlt">corals</span> (10.0 ± 1.7 %) compared to <span class="hlt">coral</span>-dominated reefs (33.4 ± 3.6 %) despite no statistical difference in their juvenile <span class="hlt">coral</span> densities. A bottleneck caused by low juvenile colony survivorship on unconsolidated rubble-dominated reefs is possible, or alternatively, recruitment to rubble-dominated reefs has only recently begun. This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23321299','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23321299"><span>Species-diverse <span class="hlt">coral</span> communities on an artificial substrate at a tuna farm in Amami, Japan.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hata, Hiroki; Hirabayashi, Isao; Hamaoka, Hideki; Mukai, Yoshio; Omori, Koji; Fukami, Hironobu</p> <p>2013-04-01</p> <p>Tuna-farming is expanding worldwide, necessitating the monitoring/managing of its effects on the natural environment. In Japan, tuna-farming is conducted on <span class="hlt">coral</span> reefs that have been damaged by mass-<span class="hlt">bleaching</span> events and crown-of-thorns starfish (COTS) outbreaks. This study focused on the <span class="hlt">coral</span> community on an artificial substrate of tuna-farm to reveal the possible effects of tuna-farming on the natural environment. <span class="hlt">Corals</span> flourished on ropes suspended in the farm in the Amami Islands, southern Japan. These were moored 3 m below the sea-surface in 50-m-deep water. The <span class="hlt">coral</span> community on the rope was analyzed and compared with those on natural substrata on two adjacent COTS-damaged reefs and with that in a protected reef. <span class="hlt">Corals</span> were monitored throughout a year. Sixty <span class="hlt">coral</span> species grew on the ropes, that corresponds to 27.3% of the 220 species known from Amami. The <span class="hlt">coral</span> community was unique, dominated by massive faviid <span class="hlt">corals</span>. On the ropes, the water temperature rarely exceeded 30.0 °C and no <span class="hlt">corals</span> on the rope were severely <span class="hlt">bleached</span> or covered by sedimentation during the observations. The tuna-farm infrastructure provided <span class="hlt">corals</span> with a suitable habitat, and species-rich <span class="hlt">coral</span> communities were established. These <span class="hlt">coral</span> communities are an important node connecting tuna-farms and the natural environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010CorRe..29..899C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010CorRe..29..899C"><span>Calcification in <span class="hlt">bleached</span> and unbleached Montastraea faveolata: evaluating the role of oxygen and glycerol</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Colombo-Pallotta, M. F.; Rodríguez-Román, A.; Iglesias-Prieto, R.</p> <p>2010-12-01</p> <p>All reef-building <span class="hlt">corals</span> are symbiotic with dinoflagellates of the genus Symbiodinium, which influences many aspects of the host’s physiology including calcification. <span class="hlt">Coral</span> calcification is a biologically controlled process performed by the host that takes place several membranes away from the site of photosynthesis performed by the symbiont. Although it is well established that light accelerates CaCO3 deposition in reef-building <span class="hlt">corals</span> (commonly referred to as light-enhanced calcification), the complete physiological mechanism behind the process is not fully understood. To better comprehend the <span class="hlt">coral</span> calcification process, a series of laboratory experiments were conducted in the major Caribbean reef-building species Montastraea faveolata, to evaluate the effect of glycerol addition and/or the super-saturation of oxygen in the seawater. These manipulations were performed in <span class="hlt">bleached</span> and unbleached <span class="hlt">corals</span>, to separate the effect of photosynthesis from calcification. The results suggest that under normal physiological conditions, a 42% increase in seawater oxygen concentration promotes a twofold increase in dark-calcification rates relative to controls. On the other hand, the results obtained using <span class="hlt">bleached</span> <span class="hlt">corals</span> suggest that glycerol is required, as a metabolic fuel, in addition to an oxygenic environment in a symbiosis that has been disrupted. Also, respiration rates in symbiotic <span class="hlt">corals</span> that were pre-incubated in light conditions showed a kinetic limitation, whereas <span class="hlt">corals</span> that were pre-incubated in darkness were oxygen limited, clearly emphasizing the role of oxygen in this regard. These findings indicate that calcification in symbiotic <span class="hlt">corals</span> is not strictly a “light-enhanced” or “dark-repressed” process, but rather, the products of photosynthesis have a critical role in calcification, which should be viewed as a “photosynthesis-driven” process. The results presented here are discussed in the context of the current knowledge of the <span class="hlt">coral</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4836920','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4836920"><span>Evaluation of temperature increase during in-office <span class="hlt">bleaching</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>MONDELLI, Rafael Francisco Lia; SOARES, Ana Flávia; PANGRAZIO, Eugenio Gabriel Kegler; WANG, Linda; ISHIKIRIAMA, Sergio Kiyoshi; BOMBONATTI, Juliana Fraga Soares</p> <p>2016-01-01</p> <p><span class="hlt">ABSTRACT</span> The use of light sources in the <span class="hlt">bleaching</span> process reduces the time required and promotes satisfactory results. However, these light sources can cause an increase in the pulp temperature. Objective The purpose of the present study was to measure the increase in intrapulpal temperature induced by different light-activated <span class="hlt">bleaching</span> procedures with and without the use of a <span class="hlt">bleaching</span> gel. Material and Methods A human maxillary central incisor was sectioned 2 mm below the cementoenamel junction. A K-type thermocouple probe was introduced into the pulp chamber. A 35% hydrogen peroxide <span class="hlt">bleaching</span> gel was applied to the vestibular tooth surface. The light units used were a conventional halogen, a hybrid light (only LED and LED/Laser), a high intensity LED, and a green LED light. Temperature increase values were compared by two-way ANOVA and Tukey´s tests (p<0.05). Results There were statistically significant differences in temperature increases between the different light sources used and between the same light sources with and without the use of a <span class="hlt">bleaching</span> gel. The presence of a <span class="hlt">bleaching</span> gel generated an increase in intra-pulpal temperature in groups activated with halogen light, hybrid light, and high intensity LED. Compared to the other light sources, the conventional halogen lamp applied over the <span class="hlt">bleaching</span> gel induced a significant increase in temperature (3.83±0.41°C). The green LED unit with and without gel application did not produce any significant intrapulpal temperature variations. Conclusion In the present study, the conventional halogen lamp caused the highest increase in intrapulpal temperature, and the green LED caused the least. There was an increase in temperature with all lights tested and the maximum temperature remained below the critical level (5.5°C). The addition of a <span class="hlt">bleaching</span> gel led to a higher increase in intrapulpal temperatures. PMID:27119761</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23029512','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23029512"><span>Physiological and biochemical performances of menthol-induced aposymbiotic <span class="hlt">corals</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Jih-Terng; Chen, Yi-Yun; Tew, Kwee Siong; Meng, Pei-Jei; Chen, Chaolun A</p> <p>2012-01-01</p> <p>The unique mutualism between <span class="hlt">corals</span> and their photosynthetic zooxanthellae (Symbiodinium spp.) is the driving force behind functional assemblages of <span class="hlt">coral</span> reefs. However, the respective roles of hosts and Symbiodinium in this endosymbiotic association, particularly in response to environmental challenges (e.g., high sea surface temperatures), remain unsettled. One of the key obstacles is to produce and maintain aposymbiotic <span class="hlt">coral</span> hosts for experimental purposes. In this study, a simple and gentle protocol to generate aposymbiotic <span class="hlt">coral</span> hosts (Isopora palifera and Stylophora pistillata) was developed using repeated incubation in menthol/artificial seawater (ASW) medium under light and in ASW in darkness, which depleted more than 99% of Symbiodinium from the host within 4∼8 days. As indicated by the respiration rate, energy metabolism (by malate dehydrogenase activity), and nitrogen metabolism (by glutamate dehydrogenase activity and profiles of free amino acids), the physiological and biochemical performances of the menthol-induced aposymbiotic <span class="hlt">corals</span> were comparable to their symbiotic counterparts without nutrient supplementation (e.g., for Stylophora) or with a nutrient supplement containing glycerol, vitamins, and a host mimic of free amino acid mixture (e.g., for Isopora). Differences in biochemical responses to menthol-induced <span class="hlt">bleaching</span> between Stylophora and Isopora were attributed to the former digesting Symbiodinium rather than expelling the algae live as found in the latter species. Our studies showed that menthol could successfully <span class="hlt">bleach</span> <span class="hlt">corals</span> and provided aposymbiotic <span class="hlt">corals</span> for further exploration of <span class="hlt">coral</span>-alga symbioses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013CorRe..32....1B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013CorRe..32....1B"><span>Relationships between temperature, <span class="hlt">bleaching</span> and white syndrome on the Great Barrier Reef</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ban, S. S.; Graham, N. A. J.; Connolly, S. R.</p> <p>2013-03-01</p> <p><span class="hlt">Coral</span> <span class="hlt">bleaching</span> and disease have often been hypothesized to be mutually reinforcing or co-occurring, but much of the research supporting this has only drawn an implicit connection through common environmental predictors. In this study, we examine whether an explicit relationship between white syndrome and <span class="hlt">bleaching</span> exists using assemblage-level monitoring data from up to 112 sites on reef slopes spread throughout the Great Barrier Reef over 11 years of monitoring. None of the temperature metrics commonly used to predict mass <span class="hlt">bleaching</span> performed strongly when applied to these data. Furthermore, the inclusion of <span class="hlt">bleaching</span> as a predictor did not improve model skill over baseline models for predicting white syndrome. Similarly, the inclusion of white syndrome as a predictor did not improve models of <span class="hlt">bleaching</span>. Evidence for spatial co-occurrence of <span class="hlt">bleaching</span> and white syndrome at the assemblage level in this data set was also very weak. These results suggest the hypothesized relationship between <span class="hlt">bleaching</span> and disease events may be weaker than previously thought, and more likely to be driven by common responses to environmental stressors, rather than directly facilitating one another.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28247459','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28247459"><span>Shifting paradigms in restoration of the world's <span class="hlt">coral</span> reefs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>van Oppen, Madeleine J H; Gates, Ruth D; Blackall, Linda L; Cantin, Neal; Chakravarti, Leela J; Chan, Wing Y; Cormick, Craig; Crean, Angela; Damjanovic, Katarina; Epstein, Hannah; Harrison, Peter L; Jones, Thomas A; Miller, Margaret; Pears, Rachel J; Peplow, Lesa M; Raftos, David A; Schaffelke, Britta; Stewart, Kristen; Torda, Gergely; Wachenfeld, David; Weeks, Andrew R; Putnam, Hollie M</p> <p>2017-03-01</p> <p>Many ecosystems around the world are rapidly deteriorating due to both local and global pressures, and perhaps none so precipitously as <span class="hlt">coral</span> reefs. Management of <span class="hlt">coral</span> reefs through maintenance (e.g., marine-protected areas, catchment management to improve water quality), restoration, as well as global and national governmental agreements to reduce greenhouse gas emissions (e.g., the 2015 Paris Agreement) is critical for the persistence of <span class="hlt">coral</span> reefs. Despite these initiatives, the health and abundance of <span class="hlt">corals</span> reefs are rapidly declining and other solutions will soon be required. We have recently discussed options for using assisted evolution (i.e., selective breeding, assisted gene flow, conditioning or epigenetic programming, and the manipulation of the <span class="hlt">coral</span> microbiome) as a means to enhance environmental stress tolerance of <span class="hlt">corals</span> and the success of <span class="hlt">coral</span> reef restoration efforts. The 2014-2016 global <span class="hlt">coral</span> <span class="hlt">bleaching</span> event has sharpened the focus on such interventionist approaches. We highlight the necessity for consideration of alternative (e.g., hybrid) ecosystem states, discuss traits of resilient <span class="hlt">corals</span> and <span class="hlt">coral</span> reef ecosystems, and propose a decision tree for incorporating assisted evolution into restoration initiatives to enhance climate resilience of <span class="hlt">coral</span> reefs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006CorRe..25..609S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006CorRe..25..609S"><span>Symbiotic crabs maintain <span class="hlt">coral</span> health by clearing sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stewart, Hannah L.; Holbrook, Sally J.; Schmitt, Russell J.; Brooks, Andrew J.</p> <p>2006-11-01</p> <p>Stony <span class="hlt">corals</span> are the foundation of <span class="hlt">coral</span> reef ecosystems and form associations with other reef species. Many of these associations may be ecologically important and play a role in maintaining the health and diversity of reef systems, rendering it critical to understand the influence of symbiotic organisms in mediating responses to perturbation. This study demonstrates the importance of an association with trapeziid crabs in reducing adverse effects of sediments deposited on <span class="hlt">corals</span>. In a field experiment, mortality rates of two species of branching <span class="hlt">corals</span> were significantly lowered by the presence of crabs. All outplanted <span class="hlt">corals</span> with crabs survived whereas 45-80% of <span class="hlt">corals</span> without crabs died within a month. For surviving <span class="hlt">corals</span> that lacked crabs, growth was slower and tissue <span class="hlt">bleaching</span> and sediment load were higher. Laboratory experiments revealed that <span class="hlt">corals</span> with crabs shed substantially more of the sediments deposited on <span class="hlt">coral</span> surfaces, but also that crabs were most effective at removing grain sizes that were most damaging to <span class="hlt">coral</span> tissues. The mechanism underlying this symbiotic relationship has not been recognized previously, and its role in maintaining <span class="hlt">coral</span> health is likely to become even more critical as reefs worldwide experience increasing sedimentation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24718371','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24718371"><span>Biogeography and change among regional <span class="hlt">coral</span> communities across the Western Indian Ocean.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McClanahan, Timothy R; Ateweberhan, Mebrahtu; Darling, Emily S; Graham, Nicholas A J; Muthiga, Nyawira A</p> <p>2014-01-01</p> <p><span class="hlt">Coral</span> reefs are biodiverse ecosystems structured by abiotic and biotic factors operating across many spatial scales. Regional-scale interactions between climate change, biogeography and fisheries management remain poorly understood. Here, we evaluated large-scale patterns of <span class="hlt">coral</span> communities in the western Indian Ocean after a major <span class="hlt">coral</span> <span class="hlt">bleaching</span> event in 1998. We surveyed 291 <span class="hlt">coral</span> reef sites in 11 countries and over 30° of latitude between 2004 and 2011 to evaluate variations in <span class="hlt">coral</span> communities post 1998 across gradients in latitude, mainland-island geography and fisheries management. We used linear mixed-effect hierarchical models to assess total <span class="hlt">coral</span> cover, the abundance of four major <span class="hlt">coral</span> families (acroporids, faviids, pocilloporids and poritiids), <span class="hlt">coral</span> genus richness and diversity, and the <span class="hlt">bleaching</span> susceptibility of the <span class="hlt">coral</span> communities. We found strong latitudinal and geographic gradients in <span class="hlt">coral</span> community structure and composition that supports the presence of a high <span class="hlt">coral</span> cover and diversity area that harbours temperature-sensitive taxa in the northern Mozambique Channel between Tanzania, northern Mozambique and northern Madagascar. <span class="hlt">Coral</span> communities in the more northern latitudes of Kenya, Seychelles and the Maldives were generally composed of fewer <span class="hlt">bleaching</span>-tolerant <span class="hlt">coral</span> taxa and with reduced richness and diversity. There was also evidence for continued declines in the abundance of temperature-sensitive taxa and community change after 2004. While there are limitations of our regional dataset in terms of spatial and temporal replication, these patterns suggest that large-scale interactions between biogeographic factors and strong temperature anomalies influence <span class="hlt">coral</span> communities while smaller-scale factors, such as the effect of fisheries closures, were weak. The northern Mozambique Channel, while not immune to temperature disturbances, shows continued signs of resistance to climate disturbances and remains a priority for future regional</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3981710','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3981710"><span>Biogeography and Change among Regional <span class="hlt">Coral</span> Communities across the Western Indian Ocean</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>McClanahan, Timothy R.; Ateweberhan, Mebrahtu; Darling, Emily S.; Graham, Nicholas A. J.; Muthiga, Nyawira A.</p> <p>2014-01-01</p> <p><span class="hlt">Coral</span> reefs are biodiverse ecosystems structured by abiotic and biotic factors operating across many spatial scales. Regional-scale interactions between climate change, biogeography and fisheries management remain poorly understood. Here, we evaluated large-scale patterns of <span class="hlt">coral</span> communities in the western Indian Ocean after a major <span class="hlt">coral</span> <span class="hlt">bleaching</span> event in 1998. We surveyed 291 <span class="hlt">coral</span> reef sites in 11 countries and over 30° of latitude between 2004 and 2011 to evaluate variations in <span class="hlt">coral</span> communities post 1998 across gradients in latitude, mainland-island geography and fisheries management. We used linear mixed-effect hierarchical models to assess total <span class="hlt">coral</span> cover, the abundance of four major <span class="hlt">coral</span> families (acroporids, faviids, pocilloporids and poritiids), <span class="hlt">coral</span> genus richness and diversity, and the <span class="hlt">bleaching</span> susceptibility of the <span class="hlt">coral</span> communities. We found strong latitudinal and geographic gradients in <span class="hlt">coral</span> community structure and composition that supports the presence of a high <span class="hlt">coral</span> cover and diversity area that harbours temperature-sensitive taxa in the northern Mozambique Channel between Tanzania, northern Mozambique and northern Madagascar. <span class="hlt">Coral</span> communities in the more northern latitudes of Kenya, Seychelles and the Maldives were generally composed of fewer <span class="hlt">bleaching</span>-tolerant <span class="hlt">coral</span> taxa and with reduced richness and diversity. There was also evidence for continued declines in the abundance of temperature-sensitive taxa and community change after 2004. While there are limitations of our regional dataset in terms of spatial and temporal replication, these patterns suggest that large-scale interactions between biogeographic factors and strong temperature anomalies influence <span class="hlt">coral</span> communities while smaller-scale factors, such as the effect of fisheries closures, were weak. The northern Mozambique Channel, while not immune to temperature disturbances, shows continued signs of resistance to climate disturbances and remains a priority for future regional</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17925275','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17925275"><span>Apoptosis and autophagy as mechanisms of dinoflagellate symbiont release during cnidarian <span class="hlt">bleaching</span>: every which way you lose.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dunn, Simon R; Schnitzler, Christine E; Weis, Virginia M</p> <p>2007-12-22</p> <p>Cnidarian <span class="hlt">bleaching</span> results from the breakdown in the symbiosis between the host cnidarian and its dinoflagellate symbiont. <span class="hlt">Coral</span> <span class="hlt">bleaching</span> in recent years has increasingly caused degradation and mortality of <span class="hlt">coral</span> reefs on a global scale. Although much is understood about the environmental causes of <span class="hlt">bleaching</span>, the underlying cellular mechanisms of symbiont release that drive the process are just beginning to be described. In this study, we investigated the roles of two cellular pathways, host cell apoptosis and autophagy, in the <span class="hlt">bleaching</span> process of the symbiotic anemone Aiptasia pallida. Host cell apoptosis was experimentally manipulated using gene knockdown of an anemone caspase by RNA interference, chemical inhibition of caspase using ZVAD-fmk and an apoptosis-inducer wortmannin. Autophagy was manipulated by chemical inhibition using wortmannin or induction using rapamycin. The applications of multiple single treatments resulted in some increased <span class="hlt">bleaching</span> in anemones under control conditions but no significant drop in <span class="hlt">bleaching</span> in individuals subjected to a hyperthermic stress. These results indicated that no single pathway is responsible for symbiont release during <span class="hlt">bleaching</span>. However, when multiple inhibitors were applied simultaneously to block both apoptosis and autophagy, there was a significant reduction in <span class="hlt">bleaching</span> in heat-stressed anemones. Our results allow us to formulate a model for cellular processes involved in the control of cnidarian <span class="hlt">bleaching</span> where apoptosis and autophagy act together in a see-saw mechanism such that if one is inhibited the other is induced. Similar interconnectivity between apoptosis and autophagy has previously been shown in vertebrates including involvement in an innate immune response to pathogens and parasites. This suggests that the <span class="hlt">bleaching</span> response could be a modified immune response that recognizes and removes dysfunctional symbionts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...517639S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...517639S"><span>Limits to the thermal tolerance of <span class="hlt">corals</span> adapted to a highly fluctuating, naturally extreme temperature environment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schoepf, Verena; Stat, Michael; Falter, James L.; McCulloch, Malcolm T.</p> <p>2015-12-01</p> <p>Naturally extreme temperature environments can provide important insights into the processes underlying <span class="hlt">coral</span> thermal tolerance. We determined the <span class="hlt">bleaching</span> resistance of Acropora aspera and Dipsastraea sp. from both intertidal and subtidal environments of the naturally extreme Kimberley region in northwest Australia. Here tides of up to 10 m can cause aerial exposure of <span class="hlt">corals</span> and temperatures as high as 37 °C that fluctuate daily by up to 7 °C. Control <span class="hlt">corals</span> were maintained at ambient nearshore temperatures which varied diurnally by 4-5 °C, while treatment <span class="hlt">corals</span> were exposed to similar diurnal variations and heat stress corresponding to ~20 degree heating days. All <span class="hlt">corals</span> hosted Symbiodinium clade C independent of treatment or origin. Detailed physiological measurements showed that these <span class="hlt">corals</span> were nevertheless highly sensitive to daily average temperatures exceeding their maximum monthly mean of ~31 °C by 1 °C for only a few days. Generally, Acropora was much more susceptible to <span class="hlt">bleaching</span> than Dipsastraea and experienced up to 75% mortality, whereas all Dipsastraea survived. Furthermore, subtidal <span class="hlt">corals</span>, which originated from a more thermally stable environment compared to intertidal <span class="hlt">corals</span>, were more susceptible to <span class="hlt">bleaching</span>. This demonstrates that while highly fluctuating temperatures enhance <span class="hlt">coral</span> resilience to thermal stress, they do not provide immunity to extreme heat stress events.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4667274','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4667274"><span>Limits to the thermal tolerance of <span class="hlt">corals</span> adapted to a highly fluctuating, naturally extreme temperature environment</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Schoepf, Verena; Stat, Michael; Falter, James L.; McCulloch, Malcolm T.</p> <p>2015-01-01</p> <p>Naturally extreme temperature environments can provide important insights into the processes underlying <span class="hlt">coral</span> thermal tolerance. We determined the <span class="hlt">bleaching</span> resistance of Acropora aspera and Dipsastraea sp. from both intertidal and subtidal environments of the naturally extreme Kimberley region in northwest Australia. Here tides of up to 10 m can cause aerial exposure of <span class="hlt">corals</span> and temperatures as high as 37 °C that fluctuate daily by up to 7 °C. Control <span class="hlt">corals</span> were maintained at ambient nearshore temperatures which varied diurnally by 4-5 °C, while treatment <span class="hlt">corals</span> were exposed to similar diurnal variations and heat stress corresponding to ~20 degree heating days. All <span class="hlt">corals</span> hosted Symbiodinium clade C independent of treatment or origin. Detailed physiological measurements showed that these <span class="hlt">corals</span> were nevertheless highly sensitive to daily average temperatures exceeding their maximum monthly mean of ~31 °C by 1 °C for only a few days. Generally, Acropora was much more susceptible to <span class="hlt">bleaching</span> than Dipsastraea and experienced up to 75% mortality, whereas all Dipsastraea survived. Furthermore, subtidal <span class="hlt">corals</span>, which originated from a more thermally stable environment compared to intertidal <span class="hlt">corals</span>, were more susceptible to <span class="hlt">bleaching</span>. This demonstrates that while highly fluctuating temperatures enhance <span class="hlt">coral</span> resilience to thermal stress, they do not provide immunity to extreme heat stress events. PMID:26627576</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20190118','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20190118"><span>What are the physiological and immunological responses of <span class="hlt">coral</span> to climate warming and disease?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mydlarz, Laura D; McGinty, Elizabeth S; Harvell, C Drew</p> <p>2010-03-15</p> <p><span class="hlt">Coral</span> mortality due to climate-associated stress is likely to increase as the oceans get warmer and more acidic. <span class="hlt">Coral</span> <span class="hlt">bleaching</span> and an increase in infectious disease are linked to above average sea surface temperatures. Despite the uncertain future for <span class="hlt">corals</span>, recent studies have revealed physiological mechanisms that improve <span class="hlt">coral</span> resilience to the effects of climate change. Some taxa of <span class="hlt">bleached</span> <span class="hlt">corals</span> can increase heterotrophic food intake and exchange symbionts for more thermally tolerant clades; this plasticity can increase the probability of surviving lethal thermal stress. <span class="hlt">Corals</span> can fight invading pathogens with a suite of innate immune responses that slow and even arrest pathogen growth and reduce further tissue damage. Several of these responses, such as the melanin cascade, circulating amoebocytes and antioxidants, are induced in <span class="hlt">coral</span> hosts during pathogen invasion or disease. Some components of immunity show thermal resilience and are enhanced during temperature stress and even in <span class="hlt">bleached</span> <span class="hlt">corals</span>. These examples suggest some plasticity and resilience to cope with environmental change and even the potential for evolution of resistance to disease. However, there is huge variability in responses among <span class="hlt">coral</span> species, and the rate of climate change is projected to be so rapid that only extremely hardy taxa are likely to survive the projected changes in climate stressors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4785229','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4785229"><span>A <span class="hlt">coral</span>-on-a-chip microfluidic platform enabling live-imaging microscopy of reef-building <span class="hlt">corals</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shapiro, Orr H.; Kramarsky-Winter, Esti; Gavish, Assaf R.; Stocker, Roman; Vardi, Assaf</p> <p>2016-01-01</p> <p><span class="hlt">Coral</span> reefs, and the unique ecosystems they support, are facing severe threats by human activities and climate change. Our understanding of these threats is hampered by the lack of robust approaches for studying the micro-scale interactions between <span class="hlt">corals</span> and their environment. Here we present an experimental platform, <span class="hlt">coral</span>-on-a-chip, combining micropropagation and microfluidics to allow direct microscopic study of live <span class="hlt">coral</span> polyps. The small and transparent <span class="hlt">coral</span> micropropagates are ideally suited for live-imaging microscopy, while the microfluidic platform facilitates long-term visualization under controlled environmental conditions. We demonstrate the usefulness of this approach by imaging <span class="hlt">coral</span> micropropagates at previously unattainable spatio-temporal resolutions, providing new insights into several micro-scale processes including <span class="hlt">coral</span> calcification, coral–pathogen interaction and the loss of algal symbionts (<span class="hlt">coral</span> <span class="hlt">bleaching</span>). <span class="hlt">Coral</span>-on-a-chip thus provides a powerful method for studying <span class="hlt">coral</span> physiology in vivo at the micro-scale, opening new vistas in <span class="hlt">coral</span> biology. PMID:26940983</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015CorRe..34.1229H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015CorRe..34.1229H"><span>Antioxidant responses to heat and light stress differ with habitat in a common reef <span class="hlt">coral</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hawkins, Thomas D.; Krueger, Thomas; Wilkinson, Shaun P.; Fisher, Paul L.; Davy, Simon K.</p> <p>2015-12-01</p> <p><span class="hlt">Coral</span> bleaching—the stress-induced collapse of the <span class="hlt">coral</span>- Symbiodinium symbiosis—is a significant driver of worldwide <span class="hlt">coral</span> reef degradation. Yet, not all <span class="hlt">corals</span> are equally susceptible to <span class="hlt">bleaching</span>, and we lack a clear understanding of the mechanisms underpinning their differential susceptibilities. Here, we focus on cellular redox regulation as a potential determinant of <span class="hlt">bleaching</span> susceptibility in the reef <span class="hlt">coral</span> Stylophora pistillata. Using slow heating (1 °C d-1) and altered irradiance, we induced <span class="hlt">bleaching</span> in S. pistillata colonies sampled from two depths [5-8 m (shallow) and 15-18 m (deep)]. There was significant depth-dependent variability in the timing and extent of <span class="hlt">bleaching</span> (loss of symbiont cells), as well as in host enzymatic antioxidant activity [specifically, superoxide dismutase and catalase (CAT)]. However, among the <span class="hlt">coral</span> fragments that <span class="hlt">bleached</span>, most did so without displaying any evidence of a host enzymatic antioxidant response. For example, both deep and shallow <span class="hlt">corals</span> suffered significant symbiont loss at elevated temperature, but only deep colonies exposed to high temperature and high light displayed any up-regulation of host antioxidant enzyme activity (CAT). Surprisingly, this preceded the equivalent antioxidant responses of the symbiont, which raises questions about the source(s) of hydrogen peroxide in the symbiosis. Overall, changes in enzymatic antioxidant activity in the symbionts were driven primarily by irradiance rather than temperature, and responses were similar across depth groups. Taken together, our results suggest that in the absence of light stress, heating of 1 °C d-1 to 4 °C above ambient is not sufficient to induce a substantial oxidative challenge in S. pistillata. We provide some of the first evidence that regulation of <span class="hlt">coral</span> enzymatic antioxidants can vary significantly depending on habitat, and, in terms of determining <span class="hlt">bleaching</span> susceptibility, our results suggest a significant role for the host's differential</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28111719','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28111719"><span>Additive effects of the herbicide glyphosate and elevated temperature on the branched <span class="hlt">coral</span> Acropora formosa in Nha Trang, Vietnam.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Amid, C; Olstedt, M; Gunnarsson, J S; Le Lan, H; Tran Thi Minh, H; Van den Brink, P J; Hellström, M; Tedengren, M</p> <p>2017-01-22</p> <p>The combined effects of the herbicide glyphosate and elevated temperature were studied on the tropical staghorn <span class="hlt">coral</span> Acropora formosa, in Nha Trang bay, Vietnam. The <span class="hlt">corals</span> were collected from two different reefs, one close to a polluted fish farm and one in a marine-protected area (MPA). In the laboratory, branches of the <span class="hlt">corals</span> were exposed to the herbicide glyphosate at ambient (28 °C) and at 3 °C elevated water temperatures (31 °C). Effects of herbicide and elevated temperature were studied on <span class="hlt">coral</span> <span class="hlt">bleaching</span> using photography and digital image analysis (new colorimetric method developed here based on grayscale), chlorophyll a analysis, and symbiotic dinoflagellate (Symbiodinium, referred to as zooxanthellae) counts. All <span class="hlt">corals</span> from the MPA started to <span class="hlt">bleach</span> in the laboratory before they were exposed to the treatments, indicating that they were very sensitive, as opposed to the <span class="hlt">corals</span> collected from the more polluted site, which were more tolerant and showed no <span class="hlt">bleaching</span> response to temperature increase or herbicide alone. However, the combined exposure to the stressors resulted in significant loss of color, proportional to loss in chlorophyll a and zooxanthellae. The difference in sensitivity of the <span class="hlt">corals</span> collected from the polluted site versus the MPA site could be explained by different symbiont types: the resilient type C3u and the stress-sensitive types C21 and C23, respectively. The additive effect of elevated temperatures and herbicides adds further weight to the notion that the <span class="hlt">bleaching</span> of <span class="hlt">coral</span> reefs is accelerated in the presence of multiple stressors. These results suggest that the <span class="hlt">corals</span> in Nha Trang bay have adapted to the ongoing pollution to become more tolerant to anthropogenic stressors, and that multiple stressors hamper this resilience. The loss of color and decrease of chlorophyll a suggest that <span class="hlt">bleaching</span> is related to concentration of chloro-pigments. The colorimetric method could be further fine-tuned and used as a precise, non</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18606553','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18606553"><span>Calcification and associated physiological parameters during a stress event in the scleractinian <span class="hlt">coral</span> Stylophora pistillata.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Moya, Aurélie; Ferrier-Pagès, Christine; Furla, Paola; Richier, Sophie; Tambutté, Eric; Allemand, Denis; Tambutté, Sylvie</p> <p>2008-09-01</p> <p>High calcification rates observed in reef <span class="hlt">coral</span> organisms are due to the symbiotic relationship established between scleractinian <span class="hlt">corals</span> and their photosynthetic dinoflagellates, commonly called zooxanthellae. Zooxanthellae are known to enhance calcification in the light, a process referred as "light-enhanced calcification". The disruption of the relationship between <span class="hlt">corals</span> and their zooxanthellae leads to <span class="hlt">bleaching</span>. <span class="hlt">Bleaching</span> is one of the major causes of the present decline of <span class="hlt">coral</span> reefs related to climate change and anthropogenic activities. In our aquaria, <span class="hlt">corals</span> experienced a chemical pollution leading to <span class="hlt">bleaching</span> and ending with the death of <span class="hlt">corals</span>. During the time course of this <span class="hlt">bleaching</span> event, we measured multiple parameters and could evidence four major consecutive steps: 1) at month 1 (January 2005), the stress affected primarily the photosystem II machinery of zooxanthellae resulting in an immediate decrease of photosystem II efficiency, 2) at month 2, the stress affected the photosynthetic production of O2 by zooxanthellae and the rate of light calcification, 3) at month 3, there was a decrease in both light and dark calcification rates, the appearance of the first oxidative damage in the zooxanthellae, the disruption of symbiosis, 4) and finally the death of <span class="hlt">corals</span> at month 6.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CorRe..35..181M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CorRe..35..181M"><span>Thermal stress markers in Colpophyllia natans provide an archive of site-specific <span class="hlt">bleaching</span> events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mallela, Jennie; Hetzinger, Steffen; Halfar, Jochen</p> <p>2016-03-01</p> <p>Tropical <span class="hlt">coral</span> reef monitoring relies heavily on in situ diver observations. However, in many reef regions resources are not available to regularly monitor reefs. This lack of historical baseline data makes it difficult to determine how different reefs respond to environmental stressors and what the implications are for management. To test whether <span class="hlt">coral</span> cores could be used to identify <span class="hlt">bleaching</span> events retrospectively, three sites in Tobago with pre-existing reef data including water quality and <span class="hlt">bleaching</span> observations were identified. Colpophyllia natans cores were examined for growth anomalies which occurred during periods of thermal stress. If present, anomalies were compared to in situ, real-time <span class="hlt">bleaching</span> observations and water quality data. Interestingly, sites with better water quality during the 2005 thermal anomaly were less prone to <span class="hlt">bleaching</span>. We suggest that by reducing terrestrial run-off (e.g., sediment and nutrients), and therefore improving marine water quality, reef managers could enhance near-shore <span class="hlt">coral</span> reef resilience during high-temperature events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28272836','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28272836"><span>Mapping carbon fate during <span class="hlt">bleaching</span> in a model cnidarian symbiosis: the application of (13) C metabolomics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hillyer, Katie E; Dias, Daniel A; Lutz, Adrian; Roessner, Ute; Davy, Simon K</p> <p>2017-03-08</p> <p><span class="hlt">Coral</span> <span class="hlt">bleaching</span> is a major threat to the persistence of <span class="hlt">coral</span> reefs. Yet we lack detailed knowledge of the metabolic interactions that determine symbiosis function and <span class="hlt">bleaching</span>-induced change. We mapped autotrophic carbon fate within the free metabolite pools of both partners of a model cnidarian-dinoflagellate symbiosis (Aiptasia-Symbiodinium) during exposure to thermal stress via the stable isotope tracer ((13) C bicarbonate), coupled to GC-MS. Symbiont photodamage and pronounced <span class="hlt">bleaching</span> coincided with substantial increases in the turnover of non(13) C-labelled pools in the dinoflagellate (lipid and starch store catabolism). However, (13) C enrichment of multiple compounds associated with ongoing carbon fixation and de novo biosynthesis pathways was maintained (glucose, fatty acid and lipogenesis intermediates). Minimal change was also observed in host pools of (13) C-enriched glucose (a major symbiont-derived mobile product). However, host pathways downstream showed altered carbon fate and/or pool composition, with accumulation of compatible solutes and nonenzymic antioxidant precursors. In hospite symbionts continue to provide mobile products to the host, but at a significant cost to themselves, necessitating the mobilization of energy stores. These data highlight the need to further elucidate the role of metabolic interactions between symbiotic partners, during the process of thermal acclimation and <span class="hlt">coral</span> <span class="hlt">bleaching</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999EOSTr..80S.238S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999EOSTr..80S.238S"><span><span class="hlt">Coral</span> choreography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Showstack, Randy</p> <p></p> <p>Viewers clicking onto the Waikiki Aquarium's “<span class="hlt">Coral</span> Research Cam” any time during daylight hours in Hawaii can catch the latest action of three species of living <span class="hlt">corals</span> (Acropora sp., Acropora elseyi,and Montipora digitata) and the yellow tang and blue tang fish swimming amongst them in an outdoor aquarium.Waikiki Aquarium Director Bruce Carlson says the camera is part of a new exhibit, “<span class="hlt">Corals</span> Are Alive!,” which encourages people to view living <span class="hlt">corals</span> close-up at the aquarium or via the Internet, in order to gain a better appreciation of the <span class="hlt">corals</span>. “Hopefully through education and awareness, people will be more interested and willing to help with conservation efforts to preserve <span class="hlt">coral</span> reefs,” says Carlson.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NatCC...3..508V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NatCC...3..508V"><span>Temporary refugia for <span class="hlt">coral</span> reefs in a warming world</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van Hooidonk, R.; Maynard, J. A.; Planes, S.</p> <p>2013-05-01</p> <p>Climate-change impacts on <span class="hlt">coral</span> reefs are expected to include temperature-induced spatially extensive <span class="hlt">bleaching</span> events. <span class="hlt">Bleaching</span> causes mortality when temperature stress persists but exposure to <span class="hlt">bleaching</span> conditions is not expected to be spatially uniform at the regional or global scale. Here we show the first maps of global projections of <span class="hlt">bleaching</span> conditions based on ensembles of IPCC AR5 (ref. ) models forced with the new Representative Concentration Pathways (RCPs). For the three RCPs with larger CO2 emissions (RCP 4.5, 6.0 and 8.5) the onset of annual <span class="hlt">bleaching</span> conditions is associated with ~ 510ppm CO2 equivalent; the median year of all locations is 2040 for the fossil-fuel aggressive RCP 8.5. Spatial patterns in the onset of annual <span class="hlt">bleaching</span> conditions are similar for each of the RCPs. For RCP 8.5, 26% of reef cells are projected to experience annual <span class="hlt">bleaching</span> conditions more than 5 years later than the median. Some of these temporary refugia include the western Indian Ocean, Thailand, the southern Great Barrier Reef and central French Polynesia. A reduction in the growth of greenhouse-gas emissions corresponding to the difference between RCP 8.5 and 6.0 delays annual <span class="hlt">bleaching</span> in ~ 23% of reef cells more than two decades, which might conceivably increase the potential for these reefs to cope with these changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15049357','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15049357"><span>Can <span class="hlt">coral</span> reefs be monitored from space?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Philipson, Petra; Lindell, Tommy</p> <p>2003-12-01</p> <p>The dramatic <span class="hlt">bleaching</span> events on the <span class="hlt">coral</span> reefs recently have enhanced the need for environmental monitoring. Remote sensing is an important constituent for monitoring of reefs, and an invaluable complement to field observations. This paper discusses the possibilities and limitations of present high resolution satellites for mapping and monitoring <span class="hlt">coral</span> reefs. The sensors with the best spatial and radiometric resolution available today, e.g. IKONOS, can be useful for mapping and monitoring of reefs, but they are too costly for global surveys. However, our <span class="hlt">coral</span> <span class="hlt">bleaching</span> studies indicate that massive <span class="hlt">bleaching</span> could be detected even from satellites with lower resolution, like Landsat, SPOT, and IRS. They could also be useful for coarser, from a spatial and thematic point of view, global mapping and updating purposes. A more detailed monitoring requires both better spatial resolution and spectral resolution than today's sensors. In the future, it is necessary to construct a more reef specific sensor with a few specially selected narrow bands and a good spatial, radiometric and temporal resolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70156471','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70156471"><span><span class="hlt">Coral</span> reef diseases in the Atlantic-Caribbean</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rogers, Caroline S.; Weil, Ernesto; Dubinsky, Zvy; Stambler, Noga</p> <p>2010-01-01</p> <p><span class="hlt">Coral</span> reefs are the jewels of the tropical oceans. They boast the highest diversity of all marine ecosystems, aid in the development and protection of other important, productive coastal marine communities, and have provided millions of people with food, building materials, protection from storms, recreation and social stability over thousands of years, and more recently, income, active pharmacological compounds and other benefits. These communities have been deteriorating rapidly in recent times. The continuous emergence of <span class="hlt">coral</span> reef diseases and increase in <span class="hlt">bleaching</span> events caused in part by high water temperatures among other factors underscore the need for intensive assessments of their ecological status and causes and their impact on <span class="hlt">coral</span> reefs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003Sci...301..929H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003Sci...301..929H"><span>Climate Change, Human Impacts, and the Resilience of <span class="hlt">Coral</span> Reefs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hughes, T. P.; Baird, A. H.; Bellwood, D. R.; Card, M.; Connolly, S. R.; Folke, C.; Grosberg, R.; Hoegh-Guldberg, O.; Jackson, J. B. C.; Kleypas, J.; Lough, J. M.; Marshall, P.; Nyström, M.; Palumbi, S. R.; Pandolfi, J. M.; Rosen, B.; Roughgarden, J.</p> <p>2003-08-01</p> <p>The diversity, frequency, and scale of human impacts on <span class="hlt">coral</span> reefs are increasing to the extent that reefs are threatened globally. Projected increases in carbon dioxide and temperature over the next 50 years exceed the conditions under which <span class="hlt">coral</span> reefs have flourished over the past half-million years. However, reefs will change rather than disappear entirely, with some species already showing far greater tolerance to climate change and <span class="hlt">coral</span> <span class="hlt">bleaching</span> than others. International integration of management strategies that support reef resilience need to be vigorously implemented, and complemented by strong policy decisions to reduce the rate of global warming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Sci...350..769S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Sci...350..769S"><span>Warm-water <span class="hlt">coral</span> reefs and climate change</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Spalding, Mark D.; Brown, Barbara E.</p> <p>2015-11-01</p> <p><span class="hlt">Coral</span> reefs are highly dynamic ecosystems that are regularly exposed to natural perturbations. Human activities have increased the range, intensity, and frequency of disturbance to reefs. Threats such as overfishing and pollution are being compounded by climate change, notably warming and ocean acidification. Elevated temperatures are driving increasingly frequent <span class="hlt">bleaching</span> events that can lead to the loss of both <span class="hlt">coral</span> cover and reef structural complexity. There remains considerable variability in the distribution of threats and in the ability of reefs to survive or recover from such disturbances. Without significant emissions reductions, however, the future of <span class="hlt">coral</span> reefs is increasingly bleak.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26564846','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26564846"><span>Warm-water <span class="hlt">coral</span> reefs and climate change.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Spalding, Mark D; Brown, Barbara E</p> <p>2015-11-13</p> <p><span class="hlt">Coral</span> reefs are highly dynamic ecosystems that are regularly exposed to natural perturbations. Human activities have increased the range, intensity, and frequency of disturbance to reefs. Threats such as overfishing and pollution are being compounded by climate change, notably warming and ocean acidification. Elevated temperatures are driving increasingly frequent <span class="hlt">bleaching</span> events that can lead to the loss of both <span class="hlt">coral</span> cover and reef structural complexity. There remains considerable variability in the distribution of threats and in the ability of reefs to survive or recover from such disturbances. Without significant emissions reductions, however, the future of <span class="hlt">coral</span> reefs is increasingly bleak.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70184426','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70184426"><span>Multi-scale remote sensing of <span class="hlt">coral</span> reefs</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Andréfouët, Serge; Hochberg, E.J.; Chevillon, Christophe; Muller-Karger, Frank E.; Brock, John C.; Hu, Chuanmin</p> <p>2005-01-01</p> <p>In this chapter we present how both direct and indirect remote sensing can be integrated to address two major <span class="hlt">coral</span> reef applications - <span class="hlt">coral</span> <span class="hlt">bleaching</span> and assessment of biodiversity. This approach reflects the current non-linear integration of remote sensing for environmental assessment of <span class="hlt">coral</span> reefs, resulting from a rapid increase in available sensors, processing methods and interdisciplinary collaborations (Andréfouët and Riegl, 2004). Moreover, this approach has greatly benefited from recent collaborations of once independent investigations (e.g., benthic ecology, remote sensing, and numerical modeling).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12920289','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12920289"><span>Climate change, human impacts, and the resilience of <span class="hlt">coral</span> reefs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hughes, T P; Baird, A H; Bellwood, D R; Card, M; Connolly, S R; Folke, C; Grosberg, R; Hoegh-Guldberg, O; Jackson, J B C; Kleypas, J; Lough, J M; Marshall, P; Nyström, M; Palumbi, S R; Pandolfi, J M; Rosen, B; Roughgarden, J</p> <p>2003-08-15</p> <p>The diversity, frequency, and scale of human impacts on <span class="hlt">coral</span> reefs are increasing to the extent that reefs are threatened globally. Projected increases in carbon dioxide and temperature over the next 50 years exceed the conditions under which <span class="hlt">coral</span> reefs have flourished over the past half-million years. However, reefs will change rather than disappear entirely, with some species already showing far greater tolerance to climate change and <span class="hlt">coral</span> <span class="hlt">bleaching</span> than others. International integration of management strategies that support reef resilience need to be vigorously implemented, and complemented by strong policy decisions to reduce the rate of global warming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014BGeo...11.4587A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014BGeo...11.4587A"><span>Release of hydrogen peroxide and antioxidants by the <span class="hlt">coral</span> Stylophora pistillata to its external milieu</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Armoza-Zvuloni, R.; Shaked, Y.</p> <p>2014-09-01</p> <p>Hydrogen peroxide (H2O2), a common reactive oxygen species, plays multiple roles in <span class="hlt">coral</span> health and disease. Elevated H2O2 production by the symbiotic algae during stress may result in symbiosis breakdown and <span class="hlt">bleaching</span> of the <span class="hlt">coral</span>. We have recently reported that various Red Sea <span class="hlt">corals</span> release H2O2 and antioxidants to their external milieu, and can influence the H2O2 dynamics in the reef. Here, we present a laboratory characterization of H2O2 and antioxidant activity release kinetics by intact, non-stressed Stylophora pistillata. Experimenting with <span class="hlt">bleached</span> and non-<span class="hlt">bleached</span> <span class="hlt">corals</span> and different stirring speeds, we explored the sources and modes of H2O2 and antioxidant release. Since H2O2 is produced and degraded simultaneously, we developed a methodology for resolving the actual H2O2 concentrations released by the <span class="hlt">corals</span>. H2O2 and antioxidant activity steadily increased in the water surrounding the <span class="hlt">coral</span> over short periods of 1-2 h. Over longer periods of 5-7 h, the antioxidant activity kept increasing with time, while H2O2 concentrations were stabilized at ~ 1 μM by 1-3 h, and then gradually declined. Solving for H2O2 release, <span class="hlt">corals</span> were found to release H2O2 at increasing rates over 2-4 h, and then to slow down and stop by 5-7 h. Stirring was shown to induce the release of H2O2, possibly since the flow reduces the thickness of the diffusive boundary layer of the <span class="hlt">coral</span>, and thus increases H2O2 mass flux. Antioxidant activity was released at similar rates by <span class="hlt">bleached</span> and non-<span class="hlt">bleached</span> <span class="hlt">corals</span>, suggesting that the antioxidants did not originate from the symbiotic algae. H2O2, however, was not released from <span class="hlt">bleached</span> <span class="hlt">corals</span>, implying that the symbiotic algae are the source of the released H2O2. The observed flow-induced H2O2 release may aid <span class="hlt">corals</span> in removing some of the internal H2O2 produced by their symbiotic algae, and may possibly assist in preventing <span class="hlt">coral</span> <span class="hlt">bleaching</span> under conditions of elevated temperature and irradiance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014BGD....11...33A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014BGD....11...33A"><span>Release of hydrogen peroxide and antioxidant by the <span class="hlt">coral</span> Stylophora pistillata to its external milieu</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Armoza-Zvuloni, R.; Shaked, Y.</p> <p>2014-01-01</p> <p>Hydrogen peroxide (H2O2), a common reactive oxygen species, plays multiple roles in <span class="hlt">coral</span> health and disease. Elevated H2O2 production by the symbiotic algae during stress may result in symbiosis breakdown and <span class="hlt">bleaching</span> of the <span class="hlt">coral</span>. We have recently reported that various Red Sea <span class="hlt">corals</span> release H2O2 and antioxidants to their external milieu and can influence the H2O2 dynamics in the reef. Here we present laboratory characterization of H2O2 and antioxidant activity release kinetics by intact, non-stressed Stylophora pistillata. Experimenting with <span class="hlt">bleached</span> and non-<span class="hlt">bleached</span> <span class="hlt">corals</span> and different stirring speeds, we explored the sources and modes of H2O2 and antioxidant release. Since H2O2 is produced and degraded simultaneously, we developed methodology for resolving the actual rates of H2O2 release by the <span class="hlt">corals</span>. H2O2 and antioxidant activity linearly increased in the water surrounding the <span class="hlt">coral</span> over short periods of 1-2 h. Over longer periods of 5-7 h, the antioxidant activity kept increasing with time, while H2O2 concentrations were stabilized at ~ 1 μM by 2-3 h, and then gradually declined. Solving for H2O2 release, <span class="hlt">corals</span> were found to release H2O2 at increasing rates over 2-4 h, and then slow down and stop by 5-7 h. Stirring was shown to induce the release of both H2O2 and antioxidant activity, possibly due to ventilation of the <span class="hlt">coral</span> by the flow. Antioxidant activity was released at similar rates by <span class="hlt">bleached</span> and non-<span class="hlt">bleached</span> <span class="hlt">corals</span>, suggesting that the antioxidant did not originate from the symbiotic algae. H2O2, however, was only minimally released from <span class="hlt">bleached</span> <span class="hlt">corals</span>, implying that the symbiotic algae are the source of the released H2O2. The observed flow-induced H2O2 release may aid <span class="hlt">corals</span> in removing some of the internal H2O2 produced by their symbiotic algae and possibly assist in preventing <span class="hlt">coral</span> <span class="hlt">bleaching</span> under conditions of elevated temperature and irradiance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23816307','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23816307"><span>Climate change impacts on <span class="hlt">coral</span> reefs: synergies with local effects, possibilities for acclimation, and management implications.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ateweberhan, Mebrahtu; Feary, David A; Keshavmurthy, Shashank; Chen, Allen; Schleyer, Michael H; Sheppard, Charles R C</p> <p>2013-09-30</p> <p>Most reviews concerning the impact of climate change on <span class="hlt">coral</span> reefs discuss independent effects of warming or ocean acidification. However, the interactions between these, and between these and direct local stressors are less well addressed. This review underlines that <span class="hlt">coral</span> <span class="hlt">bleaching</span>, acidification, and diseases are expected to interact synergistically, and will negatively influence survival, growth, reproduction, larval development, settlement, and post-settlement development of <span class="hlt">corals</span>. Interactions with local stress factors such as pollution, sedimentation, and overfishing are further expected to compound effects of climate change. Reduced <span class="hlt">coral</span> cover and species composition following <span class="hlt">coral</span> <span class="hlt">bleaching</span> events affect <span class="hlt">coral</span> reef fish community structure, with variable outcomes depending on their habitat dependence and trophic specialisation. Ocean acidification itself impacts fish mainly indirectly through disruption of predation- and habitat-associated behavior changes. Zooxanthellate octocorals on reefs are often overlooked but are substantial occupiers of space; these also are highly susceptible to <span class="hlt">bleaching</span> but because they tend to be more heterotrophic, climate change impacts mainly manifest in terms of changes in species composition and population structure. Non-calcifying macroalgae are expected to respond positively to ocean acidification and promote microbe-induced <span class="hlt">coral</span> mortality via the release of dissolved compounds, thus intensifying phase-shifts from <span class="hlt">coral</span> to macroalgal domination. Adaptation of <span class="hlt">corals</span> to these consequences of CO2 rise through increased tolerance of <span class="hlt">corals</span> and successful mutualistic associations between <span class="hlt">corals</span> and zooxanthellae is likely to be insufficient to match the rate and frequency of the projected changes. Impacts are interactive and magnified, and because there is a limited capacity for <span class="hlt">corals</span> to adapt to climate change, global targets of carbon emission reductions are insufficient for <span class="hlt">coral</span> reefs, so lower targets should be</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980002728','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980002728"><span><span class="hlt">Coral</span> Pigments: Quantification Using HPLC and Detection by Remote Sensing</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cottone, Mary C.</p> <p>1995-01-01</p> <p>Widespread <span class="hlt">coral</span> <span class="hlt">bleaching</span> (loss of pigments of symbiotic dinoflagellates), and the corresponding decline in <span class="hlt">coral</span> reef health worldwide, mandates the monitoring of <span class="hlt">coral</span> pigmentation. Samples of the <span class="hlt">corals</span> Porites compressa and P. lobata were collected from a healthy reef at Puako, Hawaii, and chlorophyll (chl) a, peridinin, and Beta-carotene (Beta-car) were quantified using reverse-phase high performance liquid chromatography (HPLC). Detailed procedures are presented for the extraction of the <span class="hlt">coral</span> pigments in 90% acetone, and the separation, identification, and quantification of the major zooxanthellar pigments using spectrophotometry and a modification of the HPLC system described by Mantoura and Llewellyn (1983). Beta-apo-8-carotenal was found to be inadequate as in internal standard, due to coelution with chl b and/or chl a allomer in the sample extracts. Improvements are suggested, which may result in better resolution of the major pigments and greater accuracy in quantification. Average concentrations of peridinin, chl a, and Beta-car in <span class="hlt">corals</span> on the reef were 5.01, 8.59, and 0.29, micro-grams/cm(exp 2), respectively. Average concentrations of peridinin and Beta-car did not differ significantly between the two <span class="hlt">coral</span> species sampled; however, the mean chl a concentration in P. compressa specimens (7.81 ,micro-grams/cm(exp 2) was significantly lower than that in P. lobata specimens (9.96 11g/cm2). Chl a concentrations determined spectrophotometrically were significantly higher than those generated through HPLC, suggesting that spectrophotometry overestimates chl a concentrations. The average ratio of chl a-to-peridinin concentrations was 1.90, with a large (53%) coefficient of variation and a significant difference between the two species sampled. Additional data are needed before conclusions can be drawn regarding average pigment concentrations in healthy <span class="hlt">corals</span> and the consistency of the chl a/peridinin ratio. The HPLC pigment concentration values</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23355025','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23355025"><span><span class="hlt">Coral</span> communities of the remote atoll reefs in the Nansha Islands, southern South China Sea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, M X; Yu, K F; Shi, Q; Chen, T R; Zhang, H L; Chen, T G</p> <p>2013-09-01</p> <p>During the months of May and June in the year 2007, a survey was conducted regarding <span class="hlt">coral</span> reef communities in the remote atolls (Zhubi Reef and Meiji Reef) of Nansha Islands, southern South China Sea. The goals of the survey were to: (1) for the first time, compile a scleractinian <span class="hlt">coral</span> check-list; (2) estimate the total richness, <span class="hlt">coral</span> cover, and growth forms of the community; and (3) describe preliminary patterns of community structure according to geomorphological units. Findings of this survey revealed a total of 120 species of scleractinia belonging to 40 genera, while the average <span class="hlt">coral</span> cover was 21 %, ranging from less than 10 % to higher than 50 %. Branching and massive <span class="hlt">corals</span> were also found to be the most important growth forms of the whole <span class="hlt">coral</span> community, while Acropora, Montipora, and Porites were the three dominant genera in the overall region, with their contributions to total <span class="hlt">coral</span> cover measuring 21, 22, and 23 %, respectively. Overall, <span class="hlt">coral</span> communities of the Nansha Islands were in a relative healthy condition with high species diversity and <span class="hlt">coral</span> cover. Spatial pattern of <span class="hlt">coral</span> communities existed among various geomorphological units. Mean <span class="hlt">coral</span> cover was highest in the patch reef within the lagoon, followed by the fore reef slope, reef flat, and lagoon slope. The greatest contributors to total <span class="hlt">coral</span> cover were branching Acropora (45 %) in the lagoon slope, branching Montipora (44 %) in the reef flat, and massive Porites (51 %) in the patch reef. <span class="hlt">Coral</span> cover in the fore reef revealed a greater range of genera than in other habitats. The leeward fore reef slope had higher <span class="hlt">coral</span> cover (> 50 %) when compared with the windward slope (< 10 %). The <span class="hlt">coral</span> communities of the inner reef flat were characterized by higher <span class="hlt">coral</span> cover (27 %) and dominant branching Montipora <span class="hlt">corals</span>, while lower <span class="hlt">coral</span> cover (4 %) was dominated by Psammocora with massive growth forms on the outer reef flat. Destructive fishing and <span class="hlt">coral</span> <span class="hlt">bleaching</span> were two major threats to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70032887','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70032887"><span>Effects of intermittent flow and irradiance level on back reef Porites <span class="hlt">corals</span> at elevated seawater temperatures</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Smith, L.W.; Birkeland, C.</p> <p>2007-01-01</p> <p><span class="hlt">Corals</span> inhabiting shallow back reef habitats are often simultaneously exposed to elevated seawater temperatures and high irradiance levels, conditions known to cause <span class="hlt">coral</span> <span class="hlt">bleaching</span>. Water flow in many tropical back reef systems is tidally influenced, resulting in semi-diurnal or diurnal flow patterns. Controlled experiments were conducted to test effects of semi-diurnally intermittent water flow on photoinhibition and <span class="hlt">bleaching</span> of the <span class="hlt">corals</span> Porites lobata and P. cylindrica kept at elevated seawater temperatures and different irradiance levels. All <span class="hlt">coral</span> colonies were collected from a shallow back reef pool on Ofu Island, American Samoa. In the high irradiance experiments, photoinhibition and <span class="hlt">bleaching</span> were less for both species in the intermittent high-low flow treatment than in the constant low flow treatment. In the low irradiance experiments, there were no differences in photoinhibition or <span class="hlt">bleaching</span> for either species between the flow treatments, despite continuously elevated seawater temperatures. These results suggest that intermittent flow associated with semi-diurnal tides, and low irradiances caused by turbidity or shading, may reduce photoinhibition and <span class="hlt">bleaching</span> of back reef <span class="hlt">corals</span> during warming events. ?? 2006 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatCC...5..688M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatCC...5..688M"><span>Projections of climate conditions that increase <span class="hlt">coral</span> disease susceptibility and pathogen abundance and virulence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maynard, Jeffrey; van Hooidonk, Ruben; Eakin, C. Mark; Puotinen, Marjetta; Garren, Melissa; Williams, Gareth; Heron, Scott F.; Lamb, Joleah; Weil, Ernesto; Willis, Bette; Harvell, C. Drew</p> <p>2015-07-01</p> <p>Rising sea temperatures are likely to increase the frequency of disease outbreaks affecting reef-building <span class="hlt">corals</span> through impacts on <span class="hlt">coral</span> hosts and pathogens. We present and compare climate model projections of temperature conditions that will increase <span class="hlt">coral</span> susceptibility to disease, pathogen abundance and pathogen virulence. Both moderate (RCP 4.5) and fossil fuel aggressive (RCP 8.5) emissions scenarios are examined. We also compare projections for the onset of disease-conducive conditions and severe annual <span class="hlt">coral</span> <span class="hlt">bleaching</span>, and produce a disease risk summary that combines climate stress with stress caused by local human activities. There is great spatial variation in the projections, both among and within the major ocean basins, in conditions favouring disease development. Our results indicate that disease is as likely to cause <span class="hlt">coral</span> mortality as <span class="hlt">bleaching</span> in the coming decades. These projections identify priority locations to reduce stress caused by local human activities and test management interventions to reduce disease impacts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004PrOce..60..263M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004PrOce..60..263M"><span><span class="hlt">Coral</span>-algal phase shifts on <span class="hlt">coral</span> reefs: Ecological and environmental aspects [review article</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McManus, John W.; Polsenberg, Johanna F.</p> <p>2004-02-01</p> <p>This paper briefly reviews <span class="hlt">coral</span>-algal phase shifts on <span class="hlt">coral</span> reefs, with particular regard to summarizing the exogenous and endogenous factors in support of a proposed conceptual model, and to identifying critical information gaps. A phase shift occurs on a <span class="hlt">coral</span> reef when the cover of a substrate by scleractinian <span class="hlt">corals</span> is reduced in favor of macroalgal dominance, and resilience of the former condition is retarded because of ecological processes and/or environmental conditions. The change is often, but not always, associated with a perturbation such as <span class="hlt">coral</span> <span class="hlt">bleaching</span>, outbreaks of a <span class="hlt">coral-eating</span> species, or storm damage. The new state is generally associated with some combination of reduced herbivory (from disease and/or fishing) and nutrient enrichment, although the relative importance of these factors is under debate and may vary among locations and even across single reefs. Disturbances that result in a state of generally low biotic three-dimensional structural complexity often precede a phase shift. Following such a disturbance, the system will pass to a state of higher biotic structural complexity, with either macroalgae or <span class="hlt">coral</span> dominating. As the community progresses towards larger and more three-dimensionally complex <span class="hlt">corals</span> or macroalgae, it exhibits greater resistance to shifting dominance from one state to the other. Studies of the phase-shift phenomena have been generally conducted at scales that are small relative to the sizes and inherent variability of whole <span class="hlt">coral</span> reefs and systems of reefs. There is an urgent need for studies aimed at quantifying and simulating cause and effect aspects of the phase shift, including human-environment coupling, particularly in support of <span class="hlt">coral</span> reef decision-making.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19269026','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19269026"><span>Scleractinian <span class="hlt">coral</span> population size structures and growth rates indicate <span class="hlt">coral</span> resilience on the fringing reefs of North Jamaica.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Crabbe, M J C</p> <p>2009-01-01</p> <p><span class="hlt">Coral</span> reefs throughout the world are under severe challenges from many environmental factors. This paper quantifies the size structure of populations and the growth rates of <span class="hlt">corals</span> from 2000 to 2008 to test whether the Discovery Bay <span class="hlt">coral</span> colonies showed resilience in the face of multiple acute stressors of hurricanes and <span class="hlt">bleaching</span>. There was a reduction in numbers of colonies in the smallest size class for all the species at all the sites in 2006, after the mass <span class="hlt">bleaching</span> of 2005, with subsequent increases for all species at all sites in 2007 and 2008. Radial growth rates (mm yr(-1)) of non-branching <span class="hlt">corals</span> and linear extension rates (mm yr(-1)) of branching <span class="hlt">corals</span> calculated on an annual basis from 2000-2008 showed few significant differences either spatially or temporally. At Dairy Bull reef, live <span class="hlt">coral</span> cover increased from 13+/-5% in 2006 to 20+/-9% in 2007 and 31+/-7% in 2008, while live Acropora species increased from 2+/-2% in 2006 to 10+/-4% in 2007 and 22+/-7% in 2008. These studies indicate good levels of <span class="hlt">coral</span> resilience on the fringing reefs around Discovery Bay in Jamaica.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012CorRe..31..473F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012CorRe..31..473F"><span>The effect of temperature stress on <span class="hlt">coral</span>- Symbiodinium associations containing distinct symbiont types</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fisher, P. L.; Malme, M. K.; Dove, S.</p> <p>2012-06-01</p> <p>Several studies have demonstrated that the temperature tolerance of scleractinian reef-building <span class="hlt">corals</span> is controlled, in part, by hosting physiologically distinct symbiotic algae. We investigated the thermal tolerance of <span class="hlt">coral</span>-algal associations within seven common species of reef-building <span class="hlt">corals</span> hosting distinct Symbiodinium sub-clades collected from Heron Island during experimentally induced <span class="hlt">bleaching</span> conditions. During experimental heating, photosynthetic fitness was assessed by the dark-adapted yield of PSII ( F v/ F m), and excitation pressure across PSII ( Q m) of each <span class="hlt">coral</span>-algal association using pulse amplitude modulation fluorometry. The onset of <span class="hlt">bleaching</span> was determined by the measurement of Symbiodinium cell density. Using the ribosomal internal transcribed spacer 2 (ITS-2) region, we showed that Symbiodinium type-<span class="hlt">coral</span> host associations were temporally and spatially conserved in a high proportion of the colonies sampled within each species. Generally, the species Acropora millepora, Platygyra daedalea, Acropora aspera and Acropora formosa contained Symbiodinium ITS-2 type C3, whereas the species Montipora digitata, Porites cylindrica and Porites lutea contained Symbiodinium type C15. <span class="hlt">Bleaching</span> susceptibility showed some association with Symbiodinium type, but further research is required to confirm this. <span class="hlt">Corals</span> hosting C3 Symbiodinium displayed higher reductions in F v/ F m during heating compared to their C15 counterparts, irrespective of host species. However, a corresponding reduction in Symbiodinium density was not observed. Nonetheless, A. aspera and A. formosa showed significant reductions in Symbiodinium density relative to controls. This correlated with large increases in Q m and decreases in F v/ F m in heated explants. Our results suggest a range of <span class="hlt">bleaching</span> susceptibilities for the <span class="hlt">coral</span> species investigated, with A. aspera and A. formosa showing the greatest susceptibility to <span class="hlt">bleaching</span> and M. digitata showing the lowest <span class="hlt">bleaching</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28391465','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28391465"><span>Resilience potential of an Indian Ocean reef: an assessment through <span class="hlt">coral</span> recruitment pattern and survivability of juvenile <span class="hlt">corals</span> to recurrent stress events.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Manikandan, Balakrishnan; Ravindran, Jeyaraman; Vidya, Pottekkatt Jayabalan; Shrinivasu, Selvaraju; Manimurali, Rajagopal; Paramasivam, Kaliyaperumal</p> <p>2017-04-09</p> <p><span class="hlt">Coral</span> reefs are degraded by the synergistic action of climate and anthropogenic stressors. <span class="hlt">Coral</span> cover in the Palk Bay reef at the northern Indian Ocean largely declined in the past decade due to frequent <span class="hlt">bleaching</span> events, tsunami and increased fishing activities. In this study, we carried out a comparative assessment to assess the differences in the recovery and resilience of three spatially distant reefs viz. Vedhalai, Mandapam and Pamban along Palk Bay affected by moderate, severe and low fishing pressure respectively. The assessment was based on the juvenile <span class="hlt">coral</span> recruitment pattern and its survivability combined with availability of hard substratum, live <span class="hlt">coral</span> cover and herbivore reef fish stock. The Vedhalai reef has the highest <span class="hlt">coral</span> cover (14.6 ± 6.3%), and ≥90% of the live <span class="hlt">corals</span> in Vedhalai and Mandapam were affected by turf algal overgrowth. The density of herbivore reef fish was low in Vedhalai and Mandapam reefs compared to the Pamban reef with relatively few grazing species. The juvenile <span class="hlt">coral</span> diversity and density were high in the Pamban reef and low in Vedhalai and Mandapam reefs despite high hard substratum cover. In total, 22 species of juvenile <span class="hlt">corals</span> of 10 genera were recorded in Palk Bay. Comparison of the species diversity of juvenile <span class="hlt">corals</span> with adult ones suggested that the Pamban reef is connected with other distant reefs whereas Vedhalai and Mandapam reefs were self-seeded. There was no statistically significant difference in the survivability of juvenile <span class="hlt">corals</span> between the study sites, and in total, ≥90% of the juvenile <span class="hlt">corals</span> survived the high sedimentation stress triggered by the northeast monsoon and <span class="hlt">bleaching</span> stress that occurred recurrently. Our results indicated that the human activities indirectly affected the juvenile <span class="hlt">coral</span> recruitment by degrading the live <span class="hlt">coral</span> cover and contributed to the spatial variation in the recovery and resilience of the Palk Bay reef. Low species diversity of the juvenile <span class="hlt">corals</span> will increase the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26119322','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26119322"><span><span class="hlt">Coral</span> population dynamics across consecutive mass mortality events.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Riegl, Bernhard; Purkis, Sam</p> <p>2015-11-01</p> <p>Annual <span class="hlt">coral</span> mortality events due to increased atmospheric heat may occur regularly from the middle of the century and are considered apocalyptic for <span class="hlt">coral</span> reefs. In the Arabian/Persian Gulf, this situation has already occurred and population dynamics of four widespread <span class="hlt">corals</span> (Acropora downingi, Porites harrisoni, Dipsastrea pallida, Cyphastrea micropthalma) were examined across the first-ever occurrence of four back-to-back mass mortality events (2009-2012). Mortality was driven by diseases in 2009, <span class="hlt">bleaching</span> and subsequent diseases in 2010/2011/2012. 2009 reduced P. harrisoni cover and size, the other events increasingly reduced overall cover (2009: -10%; 2010: -20%; 2011: -20%; 2012: -15%) and affected all examined species. Regeneration was only observed after the first disturbance. P. harrisoni and A. downingi severely declined from 2010 due to <span class="hlt">bleaching</span> and subsequent white syndromes, while D. pallida and P. daedalea declined from 2011 due to <span class="hlt">bleaching</span> and black-band disease. C. microphthalma cover was not affected. In all species, most large <span class="hlt">corals</span> were lost while fission due to partial tissue mortality bolstered small size classes. This general shrinkage led to a decrease of <span class="hlt">coral</span> cover and a dramatic reduction of fecundity. Transition matrices for disturbed and undisturbed conditions were evaluated as Life Table Response Experiment and showed that C. microphthalma changed the least in size-class dynamics and fecundity, suggesting they were 'winners'. In an ordered 'degradation cascade', impacts decreased from the most common to the least common species, leading to step-wise removal of previously dominant species. A potentially permanent shift from high- to low-<span class="hlt">coral</span> cover with different <span class="hlt">coral</span> community and size structure can be expected due to the demographic dynamics resultant from the disturbances. Similarities to degradation of other Caribbean and Pacific reefs are discussed. As comparable environmental conditions and mortality patterns must be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24335977','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24335977"><span>Unrecognized <span class="hlt">coral</span> species diversity masks differences in functional ecology.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Boulay, Jennifer N; Hellberg, Michael E; Cortés, Jorge; Baums, Iliana B</p> <p>2014-02-07</p> <p>Porites <span class="hlt">corals</span> are foundation species on Pacific reefs but a confused taxonomy hinders understanding of their ecosystem function and responses to climate change. Here, we show that what has been considered a single species in the eastern tropical Pacific, Porites lobata, includes a morphologically similar yet ecologically distinct species, Porites evermanni. While P. lobata reproduces mainly sexually, P. evermanni dominates in areas where triggerfish prey on bioeroding mussels living within the <span class="hlt">coral</span> skeleton, thereby generating asexual <span class="hlt">coral</span> fragments. These fragments proliferate in marginal habitat not colonized by P. lobata. The two Porites species also show a differential <span class="hlt">bleaching</span> response despite hosting the same dominant symbiont subclade. Thus, hidden diversity within these reef-builders has until now obscured differences in trophic interactions, reproductive dynamics and <span class="hlt">bleaching</span> susceptibility, indicative of differential responses when confronted with future climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3871303','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3871303"><span>Unrecognized <span class="hlt">coral</span> species diversity masks differences in functional ecology</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Boulay, Jennifer N.; Hellberg, Michael E.; Cortés, Jorge; Baums, Iliana B.</p> <p>2014-01-01</p> <p>Porites <span class="hlt">corals</span> are foundation species on Pacific reefs but a confused taxonomy hinders understanding of their ecosystem function and responses to climate change. Here, we show that what has been considered a single species in the eastern tropical Pacific, Porites lobata, includes a morphologically similar yet ecologically distinct species, Porites evermanni. While P. lobata reproduces mainly sexually, P. evermanni dominates in areas where triggerfish prey on bioeroding mussels living within the <span class="hlt">coral</span> skeleton, thereby generating asexual <span class="hlt">coral</span> fragments. These fragments proliferate in marginal habitat not colonized by P. lobata. The two Porites species also show a differential <span class="hlt">bleaching</span> response despite hosting the same dominant symbiont subclade. Thus, hidden diversity within these reef-builders has until now obscured differences in trophic interactions, reproductive dynamics and <span class="hlt">bleaching</span> susceptibility, indicative of differential responses when confronted with future climate change. PMID:24335977</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21778392','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21778392"><span>Projecting <span class="hlt">coral</span> reef futures under global warming and ocean acidification.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pandolfi, John M; Connolly, Sean R; Marshall, Dustin J; Cohen, Anne L</p> <p>2011-07-22</p> <p>Many physiological responses in present-day <span class="hlt">coral</span> reefs to climate change are interpreted as consistent with the imminent disappearance of modern reefs globally because of annual mass <span class="hlt">bleaching</span> events, carbonate dissolution, and insufficient time for substantial evolutionary responses. Emerging evidence for variability in the <span class="hlt">coral</span> calcification response to acidification, geographical variation in <span class="hlt">bleaching</span> susceptibility and recovery, responses to past climate change, and potential rates of adaptation to rapid warming supports an alternative scenario in which reef degradation occurs with greater temporal and spatial heterogeneity than current projections suggest. Reducing uncertainty in projecting <span class="hlt">coral</span> reef futures requires improved understanding of past responses to rapid climate change; physiological responses to interacting factors, such as temperature, acidification, and nutrients; and the costs and constraints imposed by acclimation and adaptation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011EOSTr..92..124T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011EOSTr..92..124T"><span>Research Spotlight: <span class="hlt">Corals</span> expanding poleward due to warming climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tretkoff, Ernie</p> <p>2011-04-01</p> <p><span class="hlt">Corals</span> are important organisms for ecosystems and are sensitive indicators of the effects of climate warming. While <span class="hlt">corals</span> are <span class="hlt">bleaching</span> and dying in tropical areas due to climate warming, a new study shows that in temperate areas they are expanding their range poleward as water temperatures increase. Yamano et al. used 80 years of records to study the range of <span class="hlt">corals</span> around Japan. Sea surface temperatures have risen in these temperate areas during that time. They found that four of the nine species of <span class="hlt">coral</span> they studied expanded their range northward since the 1930s, while none had its range shrink southward. The <span class="hlt">corals</span> expanded northward as quickly as 14 kilometers per year. The study suggests that rapid modifications of temperate coastal ecosystems could be taking place. (Geophysical Research Letters, doi:10.1029/2010GL046474, 2011)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26812259','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26812259"><span>Keeping It Local: Dispersal Limitations of <span class="hlt">Coral</span> Larvae to the High Latitude <span class="hlt">Coral</span> Reefs of the Houtman Abrolhos Islands.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Markey, Kathryn L; Abdo, Dave A; Evans, Scott N; Bosserelle, Cyprien</p> <p>2016-01-01</p> <p>In 2011 the first recorded <span class="hlt">bleaching</span> event for the high latitude Houtman Abrolhos Islands (HAI) <span class="hlt">coral</span> communities was documented. This <span class="hlt">bleaching</span> event highlighted the question of whether a supply of 'heat tolerant' <span class="hlt">coral</span> recruits from the tropical north would be sufficient to provide a level of resistance for these reefs to future warming events. Using Lagrangian modelling we showed that due to its regional isolation, large-scale larval input from potential tropical northern source populations to the HAI is unlikely, despite the southward flowing Leeuwin current. Successful recruitment to artificial substrates was recorded following the <span class="hlt">bleaching</span> event. However, this was negligible (0.4 ± 0.1 recruits per tile) compared to 2013 post impact recruitment (128.8 ± 15.8 recruits per tile). Our data therefore provides preliminary evidence suggesting that the connectivity of the HAI with <span class="hlt">coral</span> communities in the north is limited, and population maintenance and recovery is likely driven primarily by self-recruitment. Given the low thermal tolerance of the HAI <span class="hlt">coral</span> communities, the dominance of Acropora, and the apparent reliance on self-recruitment, an increased frequency of thermally anomalous conditions at the HAI (such as experienced in 2011) has the potential to reduce the long-term stability of the HAI <span class="hlt">coral</span> populations and species that depend upon them.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24058618','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24058618"><span>Caught in the middle: combined impacts of shark removal and <span class="hlt">coral</span> loss on the fish communities of <span class="hlt">coral</span> reefs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ruppert, Jonathan L W; Travers, Michael J; Smith, Luke L; Fortin, Marie-Josée; Meekan, Mark G</p> <p>2013-01-01</p> <p>Due to human activities, marine and terrestrial ecosystems face a future where disturbances are predicted to occur at a frequency and severity unprecedented in the recent past. Of particular concern is the ability of systems to recover where multiple stressors act simultaneously. We examine this issue in the context of a <span class="hlt">coral</span> reef ecosystem where increases in stressors, such as fisheries, benthic degradation, cyclones and <span class="hlt">coral</span> <span class="hlt">bleaching</span>, are occurring at global scales. By utilizing long-term (decadal) monitoring programs, we examined the combined effects of chronic (removal of sharks) and pulse (cyclones, <span class="hlt">bleaching</span>) disturbances on the trophic structure of <span class="hlt">coral</span> reef fishes at two isolated atoll systems off the coast of northwest Australia. We provide evidence consistent with the hypothesis that the loss of sharks can have an impact that propagates down the food chain, potentially contributing to mesopredator release and altering the numbers of primary consumers. Simultaneously, we show how the effects of bottom-up processes of <span class="hlt">bleaching</span> and cyclones appear to propagate up the food chain through herbivores, planktivores and corallivores, but do not affect carnivores. Because their presence may promote the abundance of herbivores, the removal of sharks by fishing has implications for both natural and anthropogenic disturbances involving the loss of <span class="hlt">corals</span>, as herbivores are critical to the progress and outcome of <span class="hlt">coral</span> recovery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4727885','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4727885"><span>Keeping It Local: Dispersal Limitations of <span class="hlt">Coral</span> Larvae to the High Latitude <span class="hlt">Coral</span> Reefs of the Houtman Abrolhos Islands</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Markey, Kathryn L.; Abdo, Dave A.; Evans, Scott N.; Bosserelle, Cyprien</p> <p>2016-01-01</p> <p>In 2011 the first recorded <span class="hlt">bleaching</span> event for the high latitude Houtman Abrolhos Islands (HAI) <span class="hlt">coral</span> communities was documented. This <span class="hlt">bleaching</span> event highlighted the question of whether a supply of ‘heat tolerant’ <span class="hlt">coral</span> recruits from the tropical north would be sufficient to provide a level of resistance for these reefs to future warming events. Using Lagrangian modelling we showed that due to its regional isolation, large-scale larval input from potential tropical northern source populations to the HAI is unlikely, despite the southward flowing Leeuwin current. Successful recruitment to artificial substrates was recorded following the <span class="hlt">bleaching</span> event. However, this was negligible (0.4 ± 0.1 recruits per tile) compared to 2013 post impact recruitment (128.8 ± 15.8 recruits per tile). Our data therefore provides preliminary evidence suggesting that the connectivity of the HAI with <span class="hlt">coral</span> communities in the north is limited, and population maintenance and recovery is likely driven primarily by self-recruitment. Given the low thermal tolerance of the HAI <span class="hlt">coral</span> communities, the dominance of Acropora, and the apparent reliance on self-recruitment, an increased frequency of thermally anomalous conditions at the HAI (such as experienced in 2011) has the potential to reduce the long-term stability of the HAI <span class="hlt">coral</span> populations and species that depend upon them. PMID:26812259</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3776739','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3776739"><span>Caught in the Middle: Combined Impacts of Shark Removal and <span class="hlt">Coral</span> Loss on the Fish Communities of <span class="hlt">Coral</span> Reefs</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ruppert, Jonathan L. W.; Travers, Michael J.; Smith, Luke L.; Fortin, Marie-Josée; Meekan, Mark G.</p> <p>2013-01-01</p> <p>Due to human activities, marine and terrestrial ecosystems face a future where disturbances are predicted to occur at a frequency and severity unprecedented in the recent past. Of particular concern is the ability of systems to recover where multiple stressors act simultaneously. We examine this issue in the context of a <span class="hlt">coral</span> reef ecosystem where increases in stressors, such as fisheries, benthic degradation, cyclones and <span class="hlt">coral</span> <span class="hlt">bleaching</span>, are occurring at global scales. By utilizing long-term (decadal) monitoring programs, we examined the combined effects of chronic (removal of sharks) and pulse (cyclones, <span class="hlt">bleaching</span>) disturbances on the trophic structure of <span class="hlt">coral</span> reef fishes at two isolated atoll systems off the coast of northwest Australia. We provide evidence consistent with the hypothesis that the loss of sharks can have an impact that propagates down the food chain, potentially contributing to mesopredator release and altering the numbers of primary consumers. Simultaneously, we show how the effects of bottom-up processes of <span class="hlt">bleaching</span> and cyclones appear to propagate up the food chain through herbivores, planktivores and corallivores, but do not affect carnivores. Because their presence may promote the abundance of herbivores, the removal of sharks by fishing has implications for both natural and anthropogenic disturbances involving the loss of <span class="hlt">corals</span>, as herbivores are critical to the progress and outcome of <span class="hlt">coral</span> recovery. PMID:24058618</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2011-10-14/pdf/2011-26616.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2011-10-14/pdf/2011-26616.pdf"><span>76 FR 63904 - Proposed Information Collection; Comment Request; <span class="hlt">Coral</span> Reef Conservation Program Administration</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2011-10-14</p> <p>... National Oceanic and Atmospheric Administration Proposed Information Collection; Comment Request; <span class="hlt">Coral</span>..., extension 150, or Jenny.Waddell@noaagov. SUPPLEMENTARY INFORMATION: I. <span class="hlt">Abstract</span> The <span class="hlt">Coral</span> Reef Conservation Act of 2000 (Act) was enacted to provide a framework for conserving <span class="hlt">coral</span> reefs. The <span class="hlt">Coral</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20456235','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20456235"><span>The susceptibility and resilience of <span class="hlt">corals</span> to thermal stress: adaptation, acclimatization or both?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Weis, Virginia M</p> <p>2010-04-01</p> <p><span class="hlt">Coral</span> reefs are threatened with worldwide decline from multiple factors, chief among them climate change (Hughes et al. 2003; Hoegh-Guldberg et al. 2007). The foundation of <span class="hlt">coral</span> reefs is an endosymbiosis between <span class="hlt">coral</span> hosts and their resident photosynthetic dinoflagellates (genus Symbiodinium) and this partnership (or holobiont) is exquisitely sensitive to temperature stress. The primary response to hyperthermic stress is <span class="hlt">coral</span> <span class="hlt">bleaching</span>, which is the loss of symbionts from <span class="hlt">coral</span> tissues-the collapse of the symbiosis (Weis 2008). <span class="hlt">Bleaching</span> can result in increased <span class="hlt">coral</span> mortality which can ultimately lead to severely compromised reef health (Hoegh-Guldberg et al. 2007). Despite this grim picture of <span class="hlt">coral</span> <span class="hlt">bleaching</span> and reef degradation, <span class="hlt">coral</span> susceptibility to stress and <span class="hlt">bleaching</span> is highly variable (Coles & Brown 2003). There is enormous interest in discovering the factors that determine susceptibility in order to help us predict if and how <span class="hlt">corals</span> will survive a period of rapid global warming. In this issue, Barshis et al. (2010) examine the ecophysiological and genetic basis for differential responses to stress in Porites lobata in American Samoa. They combine a reciprocal transplant experimental design between two neighbouring, but very different reef environments with state-of-the-art physiological biomarkers and molecular genetic markers for both partners to tease apart the contribution of environmental and fixed influences on stress susceptibility. Their results suggest the presence of a fixed, rather than environmental effect on expression of ubiquitin conjugates, one key marker for physiological stress response. In addition, the authors show genetic differentiation in host populations between the two sites suggesting strong selection for physiological adaptation to differing environments across small geographic distances. These conclusions point the study of <span class="hlt">coral</span> resilience and susceptibility in a new direction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17291763','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17291763"><span>Phase shifts, herbivory, and the resilience of <span class="hlt">coral</span> reefs to climate change.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hughes, Terence P; Rodrigues, Maria J; Bellwood, David R; Ceccarelli, Daniela; Hoegh-Guldberg, Ove; McCook, Laurence; Moltschaniwskyj, Natalie; Pratchett, Morgan S; Steneck, Robert S; Willis, Bette</p> <p>2007-02-20</p> <p>Many <span class="hlt">coral</span> reefs worldwide have undergone phase shifts to alternate, degraded assemblages because of the combined effects of over-fishing, declining water quality, and the direct and indirect impacts of climate change. Here, we experimentally manipulated the density of large herbivorous fishes to test their influence on the resilience of <span class="hlt">coral</span> assemblages in the aftermath of regional-scale <span class="hlt">bleaching</span> in 1998, the largest <span class="hlt">coral</span> mortality event recorded to date. The experiment was undertaken on the Great Barrier Reef, within a no-fishing reserve where <span class="hlt">coral</span> abundances and diversity had been sharply reduced by <span class="hlt">bleaching</span>. In control areas, where fishes were abundant, algal abundance remained low, whereas <span class="hlt">coral</span> cover almost doubled (to 20%) over a 3 year period, primarily because of recruitment of species that had been locally extirpated by <span class="hlt">bleaching</span>. In contrast, exclusion of large herbivorous fishes caused a dramatic explosion of macroalgae, which suppressed the fecundity, recruitment, and survival of <span class="hlt">corals</span>. Consequently, management of fish stocks is a key component in preventing phase shifts and managing reef resilience. Importantly, local stewardship of fishing effort is a tractable goal for conservation of reefs, and this local action can also provide some insurance against larger-scale disturbances such as mass <span class="hlt">bleaching</span>, which are impractical to manage directly.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26728003','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26728003"><span>Allelopathic interactions between the brown algal genus Lobophora (Dictyotales, Phaeophyceae) and scleractinian <span class="hlt">corals</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vieira, Christophe; Thomas, Olivier P; Culioli, Gérald; Genta-Jouve, Grégory; Houlbreque, Fanny; Gaubert, Julie; De Clerck, Olivier; Payri, Claude E</p> <p>2016-01-05</p> <p>Allelopathy has been recently suggested as a mechanism by which macroalgae may outcompete <span class="hlt">corals</span> in damaged reefs. Members of the brown algal genus Lobophora are commonly observed in close contact with scleractinian <span class="hlt">corals</span> and have been considered responsible for negative effects of macroalgae to scleractinian <span class="hlt">corals</span>. Recent field assays have suggested the potential role of chemical mediators in this interaction. We performed in situ bioassays testing the allelopathy of crude extracts and isolated compounds of several Lobophora species, naturally associated or not with <span class="hlt">corals</span>, against four <span class="hlt">corals</span> in New Caledonia. Our results showed that, regardless of their natural association with <span class="hlt">corals</span>, organic extracts from species of the genus Lobophora are intrinsically capable of <span class="hlt">bleaching</span> some <span class="hlt">coral</span> species upon direct contact. Additionally, three new C21 polyunsaturated alcohols named lobophorenols A-C (1-3) were isolated and identified. Significant allelopathic effects against Acropora muricata were identified for these compounds. In situ observations in New Caledonia, however, indicated that while allelopathic interactions are likely to occur at the macroalgal-<span class="hlt">coral</span> interface, Lobophora spp. rarely <span class="hlt">bleached</span> their <span class="hlt">coral</span> hosts. These findings are important toward our understanding of the importance of allelopathy versus other processes such as herbivory in the interaction between macroalgae and <span class="hlt">corals</span> in reef ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...618637V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...618637V"><span>Allelopathic interactions between the brown algal genus Lobophora (Dictyotales, Phaeophyceae) and scleractinian <span class="hlt">corals</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vieira, Christophe; Thomas, Olivier P.; Culioli, Gérald; Genta-Jouve, Grégory; Houlbreque, Fanny; Gaubert, Julie; de Clerck, Olivier; Payri, Claude E.</p> <p>2016-01-01</p> <p>Allelopathy has been recently suggested as a mechanism by which macroalgae may outcompete <span class="hlt">corals</span> in damaged reefs. Members of the brown algal genus Lobophora are commonly observed in close contact with scleractinian <span class="hlt">corals</span> and have been considered responsible for negative effects of macroalgae to scleractinian <span class="hlt">corals</span>. Recent field assays have suggested the potential role of chemical mediators in this interaction. We performed in situ bioassays testing the allelopathy of crude extracts and isolated compounds of several Lobophora species, naturally associated or not with <span class="hlt">corals</span>, against four <span class="hlt">corals</span> in New Caledonia. Our results showed that, regardless of their natural association with <span class="hlt">corals</span>, organic extracts from species of the genus Lobophora are intrinsically capable of <span class="hlt">bleaching</span> some <span class="hlt">coral</span> species upon direct contact. Additionally, three new C21 polyunsaturated alcohols named lobophorenols A–C (1–3) were isolated and identified. Significant allelopathic effects against Acropora muricata were identified for these compounds. In situ observations in New Caledonia, however, indicated that while allelopathic interactions are likely to occur at the macroalgal-<span class="hlt">coral</span> interface, Lobophora spp. rarely <span class="hlt">bleached</span> their <span class="hlt">coral</span> hosts. These findings are important toward our understanding of the importance of allelopathy versus other processes such as herbivory in the interaction between macroalgae and <span class="hlt">corals</span> in reef ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4700470','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4700470"><span>Allelopathic interactions between the brown algal genus Lobophora (Dictyotales, Phaeophyceae) and scleractinian <span class="hlt">corals</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vieira, Christophe; Thomas, Olivier P.; Culioli, Gérald; Genta-Jouve, Grégory; Houlbreque, Fanny; Gaubert, Julie; De Clerck, Olivier; Payri, Claude E.</p> <p>2016-01-01</p> <p>Allelopathy has been recently suggested as a mechanism by which macroalgae may outcompete <span class="hlt">corals</span> in damaged reefs. Members of the brown algal genus Lobophora are commonly observed in close contact with scleractinian <span class="hlt">corals</span> and have been considered responsible for negative effects of macroalgae to scleractinian <span class="hlt">corals</span>. Recent field assays have suggested the potential role of chemical mediators in this interaction. We performed in situ bioassays testing the allelopathy of crude extracts and isolated compounds of several Lobophora species, naturally associated or not with <span class="hlt">corals</span>, against four <span class="hlt">corals</span> in New Caledonia. Our results showed that, regardless of their natural association with <span class="hlt">corals</span>, organic extracts from species of the genus Lobophora are intrinsically capable of <span class="hlt">bleaching</span> some <span class="hlt">coral</span> species upon direct contact. Additionally, three new C21 polyunsaturated alcohols named lobophorenols A–C (1–3) were isolated and identified. Significant allelopathic effects against Acropora muricata were identified for these compounds. In situ observations in New Caledonia, however, indicated that while allelopathic interactions are likely to occur at the macroalgal-<span class="hlt">coral</span> interface, Lobophora spp. rarely <span class="hlt">bleached</span> their <span class="hlt">coral</span> hosts. These findings are important toward our understanding of the importance of allelopathy versus other processes such as herbivory in the interaction between macroalgae and <span class="hlt">corals</span> in reef ecosystems. PMID:26728003</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25611594','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25611594"><span>Forecasted <span class="hlt">coral</span> reef decline in marine biodiversity hotspots under climate change.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Descombes, Patrice; Wisz, Mary S; Leprieur, Fabien; Parravicini, Valerianio; Heine, Christian; Olsen, Steffen M; Swingedouw, Didier; Kulbicki, Michel; Mouillot, David; Pellissier, Loïc</p> <p>2015-01-21</p> <p><span class="hlt">Coral</span> <span class="hlt">bleaching</span> events threaten <span class="hlt">coral</span> reef habitats globally and cause severe declines of local biodiversity and productivity. Related to high sea surface temperatures (SST), <span class="hlt">bleaching</span> events are expected to increase as a consequence of future global warming. However, response to climate change is still uncertain as future low-latitude climatic conditions have no present-day analogue. Sea surface temperatures during the Eocene epoch were warmer than forecasted changes for the coming century, and distributions of <span class="hlt">corals</span> during the Eocene may help to inform models forecasting the future of <span class="hlt">coral</span> reefs. We coupled contemporary and Eocene <span class="hlt">coral</span> occurrences with information on their respective climatic conditions to model the thermal niche of <span class="hlt">coral</span> reefs and its potential response to projected climate change. We found that under the RCP8.5 climate change scenario, the global suitability for <span class="hlt">coral</span> reefs may increase up to 16% by 2100, mostly due to improved suitability of higher latitudes. In contrast, in its current range, <span class="hlt">coral</span> reef suitability may decrease up to 46% by 2100. Reduction in thermal suitability will be most severe in biodiversity hotspots, especially in the Indo-Australian Archipelago. Our results suggest that many contemporary hotspots for <span class="hlt">coral</span> reefs, including those that have been refugia in the past, spatially mismatch with future suitable areas for <span class="hlt">coral</span> reefs posing challenges to conservation actions under climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24140314','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24140314"><span>Cold enzymatic <span class="hlt">bleaching</span> of fluid whey.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Campbell, R E; Drake, M A</p> <p>2013-01-01</p> <p>Chemical <span class="hlt">bleaching</span> of fluid whey and retentate with hydrogen peroxide (HP) alone requires high concentrations (100-500 mg of HP/kg) and recent studies have demonstrated that off-flavors are generated during chemical <span class="hlt">bleaching</span> that carry through to spray-dried whey proteins. <span class="hlt">Bleaching</span> of fluid whey and retentate with enzymes such as naturally present lactoperoxidase or an exogenous commercial peroxidase (EP) at cold temperatures (4°C) may be a viable alternative to traditional chemical <span class="hlt">bleaching</span> of whey. The objective of this study was to determine the optimum level of HP for enzymatic <span class="hlt">bleaching</span> (both lactoperoxidase and EP) at 4°C and to compare <span class="hlt">bleaching</span> efficacy and sensory characteristics to HP chemical <span class="hlt">bleaching</span> at 4°C. Selected treatments were subsequently applied for whey protein concentrate with 80% protein (WPC80) manufacture. Fluid Cheddar whey and retentate (80% protein) were manufactured in triplicate from pasteurized whole milk. The optimum concentration of HP (0 to 250 mg/kg) to activate enzymatic <span class="hlt">bleaching</span> at 4°C was determined by quantifying the loss of norbixin. In subsequent experiments, <span class="hlt">bleaching</span> efficacy, descriptive sensory analysis, and volatile compounds were monitored at selected time points. A control with no <span class="hlt">bleaching</span> was also evaluated. Enzymatic <span class="hlt">bleaching</span> of fluid whey and retentate at 4°C resulted in faster <span class="hlt">bleaching</span> and higher <span class="hlt">bleaching</span> efficacy (color loss) than <span class="hlt">bleaching</span> with HP alone at 250 mg/kg. Due to concentrated levels of naturally present lactoperoxidase, retentate <span class="hlt">bleached</span> to completion (>80% norbixin destruction in 30 min) faster than fluid whey at 4°C (>80% norbixin destruction in 12h). In fluid whey, the addition of EP decreased <span class="hlt">bleaching</span> time. Spray-dried WPC80 from <span class="hlt">bleached</span> wheys, regardless of <span class="hlt">bleaching</span> treatment, were characterized by a lack of sweet aromatic and buttery flavors, and the presence of cardboard flavor concurrent with higher relative abundance of 1-octen-3-ol and 1-octen-3-one. Among enzymatically</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26602440','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26602440"><span>Living on the edge: Vulnerability of <span class="hlt">coral</span>-dependent fishes in the Gulf.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Buchanan, Jack R; Krupp, Friedhelm; Burt, John A; Feary, David A; Ralph, Gina M; Carpenter, Kent E</p> <p>2016-04-30</p> <p>In the Gulf, multiple human impacts and recurrent <span class="hlt">bleaching</span> events have resulted in serious declines of <span class="hlt">coral</span> assemblages, particularly in near-shore areas. However, the degree to which the extinction risk of <span class="hlt">coral</span>-dependent fishes is impacted by these <span class="hlt">coral</span> declines has been uncertain. Using primary literature and expert knowledge, <span class="hlt">coral</span>-dependent fishes of the Gulf were identified and species-specific data on the regional distribution, population status, life history characteristics, and major threats were compiled to determine their likelihood of extinction under the IUCN Red List of Threatened Species' Categories and Criteria. Due to the limited area and degraded and fragmented nature of <span class="hlt">coral</span> assemblages in the Gulf, all <span class="hlt">coral</span>-dependent fishes (where data was sufficient to assess) were listed at elevated risk of extinction. Cross-boundary collaboration among Gulf States is necessary for effective management and protection of <span class="hlt">coral</span> assemblages and their associated communities within this globally important region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4841221','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4841221"><span>Changes to <span class="hlt">coral</span> health and metabolic activity under oxygen deprivation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Richmond, Robert H.</p> <p>2016-01-01</p> <p>On Hawaiian reefs, the fast-growing, invasive algae Gracilaria salicornia overgrows <span class="hlt">coral</span> heads, restricting water flow and light, thereby smothering <span class="hlt">corals</span>. Field data shows hypoxic conditions (dissolved oxygen (DO2) < 2 mg/L) occurring underneath algal mats at night, and concurrent <span class="hlt">bleaching</span> and partial tissue loss of shaded <span class="hlt">corals</span>. To analyze the impact of nighttime oxygen-deprivation on <span class="hlt">coral</span> health, this study evaluated changes in <span class="hlt">coral</span> metabolism through the exposure of <span class="hlt">corals</span> to chronic hypoxic conditions and subsequent analyses of lactate, octopine, alanopine, and strombine dehydrogenase activities, critical enzymes employed through anaerobic respiration. Following treatments, lactate and octopine dehydrogenase activities were found to have no significant response in activities with treatment and time. However, <span class="hlt">corals</span> subjected to chronic nighttime hypoxia were found to exhibit significant increases in alanopine dehydrogenase activity after three days of exposure and strombine dehydrogenase activity starting after one overnight exposure cycle. These findings provide new insights into <span class="hlt">coral</span> metabolic shifts in extremely low-oxygen environments and point to ADH and SDH assays as tools for quantifying the impact of hypoxia on <span class="hlt">coral</span> health. PMID:27114888</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18175015','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18175015"><span>10th Anniversary Review: a changing climate for <span class="hlt">coral</span> reefs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lough, Janice M</p> <p>2008-01-01</p> <p>Tropical <span class="hlt">coral</span> reefs are charismatic ecosystems that house a significant proportion of the world's marine biodiversity. Their valuable goods and services are fundamental to the livelihood of large coastal populations in the tropics. The health of many of the world's <span class="hlt">coral</span> reefs, and the goods and services they provide, have already been severely compromised, largely due to over-exploitation by a range of human activities. These local-scale impacts, with the appropriate government instruments, support and management actions, can potentially be controlled and even ameliorated. Unfortunately, other human actions (largely in countries outside of the tropics), by changing global climate, have added additional global-scale threats to the continued survival of present-day <span class="hlt">coral</span> reefs. Moderate warming of the tropical oceans has already resulted in an increase in mass <span class="hlt">coral</span> <span class="hlt">bleaching</span> events, affecting nearly all of the world's <span class="hlt">coral</span> reef regions. The frequency of these events will only increase as global temperatures continue to rise. Weakening of <span class="hlt">coral</span> reef structures will be a more insidious effect of changing ocean chemistry, as the oceans absorb part of the excess atmospheric carbon dioxide. More intense tropical cyclones, changed atmospheric and ocean circulation patterns will all affect <span class="hlt">coral</span> reef ecosystems and the many associated plants and animals. <span class="hlt">Coral</span> reefs will not disappear but their appearance, structure and community make-up will radically change. Drastic greenhouse gas mitigation strategies are necessary to prevent the full consequences of human activities causing such alterations to <span class="hlt">coral</span> reef ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3202587','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3202587"><span>Development of Gene Expression Markers of Acute Heat-Light Stress in Reef-Building <span class="hlt">Corals</span> of the Genus Porites</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kenkel, Carly D.; Aglyamova, Galina; Alamaru, Ada; Bhagooli, Ranjeet; Capper, Roxana; Cunning, Ross; deVillers, Amanda; Haslun, Joshua A.; Hédouin, Laetitia; Keshavmurthy, Shashank; Kuehl, Kristin A.; Mahmoud, Huda; McGinty, Elizabeth S.; Montoya-Maya, Phanor H.; Palmer, Caroline V.; Pantile, Raffaella; Sánchez, Juan A.; Schils, Tom; Silverstein, Rachel N.; Squiers, Logan B.; Tang, Pei-Ciao; Goulet, Tamar L.; Matz, Mikhail V.</p> <p>2011-01-01</p> <p><span class="hlt">Coral</span> reefs are declining worldwide due to increased incidence of climate-induced <span class="hlt">coral</span> <span class="hlt">bleaching</span>, which will have widespread biodiversity and economic impacts. A simple method to measure the sub-<span class="hlt">bleaching</span> level of heat-light stress experienced by <span class="hlt">corals</span> would greatly inform reef management practices by making it possible to assess the distribution of <span class="hlt">bleaching</span> risks among individual reef sites. Gene expression analysis based on quantitative PCR (qPCR) can be used as a diagnostic tool to determine <span class="hlt">coral</span> condition in situ. We evaluated the expression of 13 candidate genes during heat-light stress in a common Caribbean <span class="hlt">coral</span> Porites astreoides, and observed strong and consistent changes in gene expression in two independent experiments. Furthermore, we found that the apparent return to baseline expression levels during a recovery phase was rapid, despite visible signs of colony <span class="hlt">bleaching</span>. We show that the response to acute heat-light stress in P. astreoides can be monitored by measuring the difference in expression of only two genes: Hsp16 and actin. We demonstrate that this assay discriminates between <span class="hlt">corals</span> sampled from two field sites experiencing different temperatures. We also show that the assay is applicable to an Indo-Pacific congener, P. lobata, and therefore could potentially be used to diagnose acute heat-light stress on <span class="hlt">coral</span> reefs worldwide. PMID:22046408</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21423742','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21423742"><span>Disturbance and the dynamics of <span class="hlt">coral</span> cover on the Great Barrier Reef (1995-2009).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Osborne, Kate; Dolman, Andrew M; Burgess, Scott C; Johns, Kerryn A</p> <p>2011-03-10</p> <p><span class="hlt">Coral</span> reef ecosystems worldwide are under pressure from chronic and acute stressors that threaten their continued existence. Most obvious among changes to reefs is loss of hard <span class="hlt">coral</span> cover, but a precise multi-scale estimate of <span class="hlt">coral</span> cover dynamics for the Great Barrier Reef (GBR) is currently lacking. Monitoring data collected annually from fixed sites at 47 reefs across 1300 km of the GBR indicate that overall regional <span class="hlt">coral</span> cover was stable (averaging 29% and ranging from 23% to 33% cover across years) with no net decline between 1995 and 2009. Subregional trends (10-100 km) in hard <span class="hlt">coral</span> were diverse with some being very dynamic and others changing little. <span class="hlt">Coral</span> cover increased in six subregions and decreased in seven subregions. Persistent decline of <span class="hlt">corals</span> occurred in one subregion for hard <span class="hlt">coral</span> and Acroporidae and in four subregions in non-Acroporidae families. Change in Acroporidae accounted for 68% of change in hard <span class="hlt">coral</span>. Crown-of-thorns starfish (Acanthaster planci) outbreaks and storm damage were responsible for more <span class="hlt">coral</span> loss during this period than either <span class="hlt">bleaching</span> or disease despite two mass <span class="hlt">bleaching</span> events and an increase in the incidence of <span class="hlt">coral</span> disease. While the limited data for the GBR prior to the 1980's suggests that <span class="hlt">coral</span> cover was higher than in our survey, we found no evidence of consistent, system-wide decline in <span class="hlt">coral</span> cover since 1995. Instead, fluctuations in <span class="hlt">coral</span> cover at subregional scales (10-100 km), driven mostly by changes in fast-growing Acroporidae, occurred as a result of localized disturbance events and subsequent recovery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002ECSS...55..547B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002ECSS...55..547B"><span>DMSP in <span class="hlt">Corals</span> and Benthic Algae from the Great Barrier Reef</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Broadbent, A. D.; Jones, G. B.; Jones, R. J.</p> <p>2002-10-01</p> <p>In this study the first measurements of DMSP in six species of <span class="hlt">corals</span> and ten species of benthic algae collected from four <span class="hlt">coral</span> reefs in the Great Barrier Reef are reported, together with DMSP measurements made on cultured zooxanthellae. Concentrations ranged from 21 to 3831 (mean=743) fmol DMSP zooxanthellae -1 in <span class="hlt">corals</span>, 0·16 to 2·96 nmol DMSP cm -2 (mean=90) for benthic macroalgae, and 48-285 fmol DMSP zooxanthellae -1 (mean=153) for cultured zooxanthellae. The highest concentrations of DMSP in <span class="hlt">corals</span> occurred in Acropora formosa (mean=371 fmol DMSP zooxanthellae -1) and Acropora palifera (mean=3341 fmol DMSP zooxanthellae -1) with concentrations in A. palifera the highest DMSP concentrations reported in <span class="hlt">corals</span> examined to date. As well as inter-specific differences in DMSP, intra-specific variation was also observed. Adjacent colonies of A. formosa that are known to have different thermal <span class="hlt">bleaching</span> thresholds and morphologically distinct zooxanthellae, were also observed to have different DMSP concentrations, with the zooxanthellae in the colony that <span class="hlt">bleached</span> containing DMSP at an average concentration of 436 fmol zooxanthellae -1, whilst the non-<span class="hlt">bleaching</span> colony contained DMSP at an average concentration of 171 fmol zooxanthellae -1. The results of the present study have been used to calculate the area normalized DMSP concentrations in benthic algae (mean=0·015 mmol m -2) and <span class="hlt">corals</span> (mean=2·22 mmol m -2) from the GBR. This data indicates that benthic algae and <span class="hlt">corals</span> are a significant reservoir of DMSP in GBR waters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5233991','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5233991"><span><span class="hlt">Bleaching</span> drives collapse in reef carbonate budgets and reef growth potential on southern Maldives reefs</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Perry, C. T.; Morgan, K. M.</p> <p>2017-01-01</p> <p>Sea-surface temperature (SST) warming events, which are projected to increase in frequency and intensity with climate change, represent major threats to <span class="hlt">coral</span> reefs. How these events impact reef carbonate budgets, and thus the capacity of reefs to sustain vertical growth under rising sea levels, remains poorly quantified. Here we quantify the magnitude of changes that followed the ENSO-induced SST warming that affected the Indian Ocean region in mid-2016. Resultant <span class="hlt">coral</span> <span class="hlt">bleaching</span> caused an average 75% reduction in <span class="hlt">coral</span> cover (present mean 6.2%). Most critically we report major declines in shallow fore-reef carbonate budgets, these shifting from strongly net positive (mean 5.92 G, where G = kg CaCO3 m−2 yr−1) to strongly net negative (mean −2.96 G). These changes have driven major reductions in reef growth potential, which have declined from an average 4.2 to −0.4 mm yr−1. Thus these shallow fore-reef habitats are now in a phase of net erosion. Based on past <span class="hlt">bleaching</span> recovery trajectories, and predicted increases in <span class="hlt">bleaching</span> frequency, we predict a prolonged period of suppressed budget and reef growth states. This will limit reef capacity to track IPCC projections of sea-level rise, thus limiting the natural breakwater capacity of these reefs and threatening reef island stability. PMID:28084450</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28084450','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28084450"><span><span class="hlt">Bleaching</span> drives collapse in reef carbonate budgets and reef growth potential on southern Maldives reefs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Perry, C T; Morgan, K M</p> <p>2017-01-13</p> <p>Sea-surface temperature (SST) warming events, which are projected to increase in frequency and intensity with climate change, represent major threats to <span class="hlt">coral</span> reefs. How these events impact reef carbonate budgets, and thus the capacity of reefs to sustain vertical growth under rising sea levels, remains poorly quantified. Here we quantify the magnitude of changes that followed the ENSO-induced SST warming that affected the Indian Ocean region in mid-2016. Resultant <span class="hlt">coral</span> <span class="hlt">bleaching</span> caused an average 75% reduction in <span class="hlt">coral</span> cover (pr