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Sample records for reef bleaching events

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

    Science.gov (United States)

    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 (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.

  2. Coral reef bleaching: ecological perspectives

    Science.gov (United States)

    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

  3. The abundance of herbivorous fish on an inshore Red Sea reef following a mass coral bleaching event

    KAUST Repository

    Khalil, Maha T.; Cochran, Jesse; Berumen, Michael L.

    2013-01-01

    and scarine labrids) were comparatively studied for an inshore reef that was severely impacted by a mass coral bleaching event in 2010 and an unaffected reef within the same region. Densities were found to be significantly higher on the affected reef, most

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

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    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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Pigmentation changes in Siderastrea spp. during bleaching events in the costal reefs of northeastern Brazil

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    Roberto Sassi

    2015-03-01

    Full Text Available We report here the occurrence of seasonal changes in the pigmentation of colonies of Siderastrea spp. during bleaching events on coastal reefs in northeastern Brazil. Bleached affected almost 50% of coral colonies analyzed in Cabo Branco reefs (Paraiba state in the summer of 2005. The same phenomenon was detected along various coastal reefs in northeastern Brazil during the summer of 2007 and 2008. These events were seasonal, and began with the emergence of pale colonies that became pale-pink and then purple during the rainy months. The patterns and intensity of colonies pigmentation changes varied with the studied sites. The decrease in zooxanthellae density and chlorophyll-a content was quantified in the colonies with their pigmentation pattern altered (bleaching. Microbiological analyses revealed higher densities of bacteria in pink colonies (bleached as compared to brown colonies (normal. Environmental disturbances may lead to the pigmentation changes in Siderastrea spp., but the immediate causes of this phenomenon are not clear and require further investigations.

  6. Impact of Three Bleaching Events on the Reef Resiliency of Kāne‘ohe Bay, Hawai‘i

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    Keisha D. Bahr

    2017-12-01

    Full Text Available Coral bleaching events have been increasing in frequency and severity worldwide. The most prolonged global bleaching event began in 2014 and continued into 2017 impacting more reefs than any previous occurrence. Here we present the results of coral bleaching and mortality surveys conducted in Kāne‘ohe Bay O‘ahu, Hawai‘i and compare them to the only other widespread bleaching events to impact the main Hawaiian Islands in 1996 and 2014. Results from these surveys along with associated environmental factors were used to compare these events to gain a baseline understanding of the physical processes that influence localized bleaching dynamics under these extreme environmental conditions. Survey results show extensive variation in bleaching (1996–62%, 2014–45%, 2015–30% and cumulative mortality (1996— <1%, 2014–13%, 2015–22% between years. Bleaching prevalence was observed to decrease in certain reef areas across events, suggesting some acclimation and/or resilience, but possible increase susceptibility to mortality. Long-term monitoring sites show a similar temporal pattern of coral mortality and decline in coral cover, but revealed some reefs remained relatively un-impacted by consecutive high temperature events. Across the three bleaching events, we found that although circulation patterns can facilitate heating, the duration and magnitude of the high temperature event were the primary forcing functions for coral bleaching and mortality. Other localized primary drivers influencing water temperature such as irradiance, turbidity, and precipitation contributed to spatial variations. Recovery and resilience of this coral reef ecosystem is dependent on many factors including duration and magnitude of heating, resulting mortality levels, localized environmental factors in the bay, and coral species affected and their bleaching tolerances.

  7. Status of the Coral Reefs of Maldives after the Bleaching Event in 1998

    OpenAIRE

    Zahir, H.

    2000-01-01

    A pilot reef monitoring study was conducted in 1998 to assess the extent of coral bleaching in the Maldives. The aims of this monitoring exercise were: 1. To quantitatively document the post-bleaching status of the shallow-water coral communities on the reefs of the north, central and southern regions of Maldives. 2. To estimate bleaching-induced coral mortality by comparing data yielded by the pilot survey with data from previous surveys, especially those sites for which historical dat...

  8. Elevated temperatures and bleaching on a high latitude coral reef: the 1988 Bermuda event

    Science.gov (United States)

    Cook, Clayton B.; Logan, Alan; Ward, Jack; Luckhurst, Brian; Berg, Carl J.

    1990-03-01

    Sea temperatures were normal in Bermuda during 1987, when Bermuda escaped the episodes of coral bleaching which were prevalent throughout the Caribbean region. Survey transecs in 1988 on 4 6 m reefs located on the rim margin and on a lagoonal patch reef revealed bleaching only of zoanthids between May and July. Transect and tow surveys in August and September revealed bleaching of several coral species; Millepora alcicornis on rim reefs was the most extensively affected. The frequency of bleaching in this species, Montastrea annularis and perhaps Diploria labyrinthiformis was significantly higher on outer reefs than on inshore reefs. This bleaching period coincided with the longest period of elevated sea temperatures in Bermuda in 38 years (28.9 30.9°C inshore, >28° offshore). By December, when temperatures had returned to normal, bleaching of seleractinians continued, but bleaching of M. alcicornis on the outer reefs was greatly reduced. Our observations suggest that corals which normally experience wide temperature ranges are less sensitive to thermal stress, and that high-latitude reef corals are sensitive to elevated temperatures which are within the normal thermal range of corals at lower latitudes.

  9. A Crucial Time for Reefs: Climate Change, El Niño, and the 2014-16 Global Bleaching Event

    Science.gov (United States)

    Eakin, C. M.; Liu, G.; Geiger, E.; Heron, S. F.; Skirving, W. J.; De La Cour, J. L.; Strong, A. E.; Tirak, K.; Burgess, T.

    2016-02-01

    Anthropogenic climate change has caused an increase in the frequency and intensity of coral bleaching, mortality, and other impacts detrimental to the health and survival of coral reefs around the world. In 2014, a global-scale bleaching event, anticipated to last two years or more, began in the Pacific Ocean. Severe bleaching was documented in Guam, the Commonwealth of the Northern Mariana Islands, Hawaii, and the Marshall Islands, among other locations. By mid-2015, severe bleaching had reached many south Pacific Islands and islands of the central to eastern equatorial Pacific, especially Kiribati and Howland and Baker Islands. Bleaching followed in the Indian Ocean, and at the time of this writing is again striking Hawaii, and parts of the Caribbean. As the ongoing El Niño continues to strengthen, long-term outlooks suggest the cycle of bleaching will continue into 2016 in at least the Pacific and Indian Oceans. Caribbean bleaching may follow again in 2016 if this event follows historical patterns. Warming of the global ocean, the El Niño, a new Pacific oceanic feature known as "The Blob", and other patterns are imposing thermal stress capable of causing widespread negative impacts on reefs in many countries and archipelagos. If a subsequent La Niña follows, as is often the case, even more reefs will be subjected to stressful high temperatures. This is resulting in widespread bleaching, disease, and mortality at a frequency and intensity predicted in climate models nearly two decades ago. The question now is if we are seeing the onset of annually returning coral bleaching or if this is just a hint of conditions coming in future decades. This presentation will discuss the latest information on the ongoing third global bleaching event and the impacts it may have on the biology, ecology, and potential for conservation and restoration of corals and coral reefs worldwide.

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

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    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. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  11. The Gulf of Carpentaria heated Torres Strait and the Northern Great Barrier Reef during the 2016 mass coral bleaching event

    NARCIS (Netherlands)

    Wolanski, E.; Andutta, Fernando P.; Deleersnijder, E.L.C.; Li, Y.; Thomas, C.J.

    The 2015/16 ENSO event increased the temperature of waters surrounding northeast Australia to above 30 °C, with large patches of water reaching 32 °C, for over two months, which led to severe bleaching of corals of the Northern Great Barrier Reef (NGBR). This study provides evidence gained from

  12. The abundance of herbivorous fish on an inshore Red Sea reef following a mass coral bleaching event

    KAUST Repository

    Khalil, Maha T.

    2013-01-08

    A healthy herbivore community is critical for the ability of a reef to resist and recover from severe disturbances and to regain lost coral cover (i.e., resilience). The densities of the two major herbivorous fish groups (the family Acanthuridae and scarine labrids) were comparatively studied for an inshore reef that was severely impacted by a mass coral bleaching event in 2010 and an unaffected reef within the same region. Densities were found to be significantly higher on the affected reef, most likely due to the high algal densities on that reef. However, densities of herbivores on both reefs were found to be on average about 1-2 orders of magnitude lower than previously published reports from some Pacific reefs and from Red Sea reefs in the Gulf of Aqaba and only slightly higher than Caribbean reefs. Thus, it is predicted that recovery for this reef and similarly affected reefs may be very slow. The protection of herbivores from overfishing and the introduction of other management strategies that maximize reef resilience in Saudi Arabian waters are highly recommended. © 2013 Springer Science+Business Media Dordrecht.

  13. Predation by feeding aggregations of Drupella spp. inhibits the recovery of reefs damaged by a mass bleaching event

    Science.gov (United States)

    Bruckner, Andrew W.; Coward, Georgia; Bimson, Kathyrn; Rattanawongwan, Tipwimon

    2017-12-01

    High densities of two corallivorous gastropods, Drupella cornus and D. rugosa, may delay the recovery of coral reefs impacted by mass bleaching events by aggregating on the remaining corals. Following severe bleaching in April/May 2016 that resulted in the loss of up to 80% of the living coral cover from reefs in South Malé, Maldives, aggregations of up to 250 Drupella per coral were recorded on surviving colonies. The distribution of snails was not random; larger aggregations were seen on reefs with fewer remaining live corals and also on the largest corals. Branching, digitate and tabular corals, especially species of Acropora and Pocillopora, sustained the highest mortality from the bleaching. Remaining colonies of these taxa exhibited the highest occurrence of snails and the most extensive snail predation, although less-preferred taxa such as Montipora, Porites, Astreopora, Cyphastrea and Pachyseris were also targeted. Drupella also concentrated on broken Acropora branches and overturned colonies; on some reefs, these were the only surviving acroporids, and many of them did not bleach. Continued predation pressure from Drupella may eliminate formerly dominant corals, including genets that are resistant to higher sea water temperatures.

  14. Resilience in carbonate production despite three coral bleaching events in 5 years on an inshore patch reef in the Florida Keys.

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    Manzello, Derek P; Enochs, Ian C; Kolodziej, Graham; Carlton, Renée; Valentino, Lauren

    2018-01-01

    The persistence of coral reef frameworks requires that calcium carbonate (CaCO 3 ) production by corals and other calcifiers outpaces CaCO 3 loss via physical, chemical, and biological erosion. Coral bleaching causes declines in CaCO 3 production, but this varies with bleaching severity and the species impacted. We conducted census-based CaCO 3 budget surveys using the established ReefBudget approach at Cheeca Rocks, an inshore patch reef in the Florida Keys, annually from 2012 to 2016. This site experienced warm-water bleaching in 2011, 2014, and 2015. In 2017, we obtained cores of the dominant calcifying coral at this site, Orbicella faveolata , to understand how calcification rates were impacted by bleaching and how they affected the reef-wide CaCO 3 budget. Bleaching depressed O. faveolata growth and the decline of this one species led to an overestimation of mean (± std. error) reef-wide CaCO 3 production by + 0.68 (± 0.167) to + 1.11 (± 0.236) kg m -2  year -1 when using the static ReefBudget coral growth inputs. During non-bleaching years, the ReefBudget inputs slightly underestimated gross production by - 0.10 (± 0.022) to - 0.43 (± 0.100) kg m -2  year -1 . Carbonate production declined after the first year of back-to-back bleaching in 2014, but then increased after 2015 to values greater than the initial surveys in 2012. Cheeca Rocks is an outlier in the Caribbean and Florida Keys in terms of coral cover, carbonate production, and abundance of O. faveolata , which is threatened under the Endangered Species Act. Given the resilience of this site to repeated bleaching events, it may deserve special management attention.

  15. The Gulf of Carpentaria heated Torres Strait and the Northern Great Barrier Reef during the 2016 mass coral bleaching event

    Science.gov (United States)

    Wolanski, E.; Andutta, F.; Deleersnijder, E.; Li, Y.; Thomas, C. J.

    2017-07-01

    The 2015/16 ENSO event increased the temperature of waters surrounding northeast Australia to above 30 °C, with large patches of water reaching 32 °C, for over two months, which led to severe bleaching of corals of the Northern Great Barrier Reef (NGBR). This study provides evidence gained from remote-sensing data, oceanographic data and oceanographic modeling, that three factors caused this excessive heating, namely: 1) the shutdown of the North Queensland Coastal Current, which would otherwise have flushed and cooled the Northern Coral Sea and the NGBR through tidal mixing 2) the advection of warm (>30 °C) water from the Gulf of Carpentaria eastward through Torres Strait and then southward over the NGBR continental shelf, and 3) presumably local solar heating. The eastward flux of this warm water through Torres Strait was driven by a mean sea level difference on either side of the strait that in turn was controlled by the wind, which also generated the southward advection of this warm water onto the NGBR shelf. On the NGBR shelf, the residence time of this warm water was longer inshore than offshore, and this may explain the observed cross-shelf gradient of coral bleaching intensity. The fate of the Great Barrier Reef is thus controlled by the oceanography of surrounding seas.

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

    Science.gov (United States)

    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.

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

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    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 bleaching can have substantial long-term impacts on coral communities, even in areas with corals tolerant to environmental extremes. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

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    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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Large-scale bleaching of corals on the Great Barrier Reef.

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    Hughes, T P; Kerry, J T; Simpson, T

    2018-02-01

    In 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching. In the southern hemisphere summer of March-April 2016, we used aerial surveys to measure the level of bleaching on 1,156 individual reefs throughout the 2,300 km length of the Great Barrier Reef, the world's largest coral reef system. The accuracy of the aerial scores was ground-truthed with detailed underwater surveys of bleaching at 260 sites (104 reefs), allowing us to compare aerial and underwater bleaching data with satellite-derived temperatures and with associated model predictions of bleaching. The severity of bleaching on individual reefs in 2016 was tightly correlated with the level of local heat exposure: the southernmost region of the Great Barrier Reef escaped with only minor bleaching because summer temperatures there were close to average. Gradients in nutrients and turbidity from inshore to offshore across the Great Barrier Reef had minimal effect on the severity of bleaching. Similarly, bleaching was equally severe on reefs that are open or closed to fishing, once the level of satellite-derived heat exposure was accounted for. The level of post-bleaching mortality, measured underwater after 7-8 months, was tightly correlated with the aerial scores measured at the peak of bleaching. Similarly, reefs with a high aerial bleaching score also experienced major shifts in species composition due to extensive mortality of heat-sensitive species. Reefs with low bleaching scores did not change in composition, and some showed minor increases in coral cover. Two earlier mass bleaching events occurred on the Great Barrier Reef in 1998 and 2002, that were less severe than 2016. In 2016, bleaching, compared to 42% in 2002 and 44% in 1998. Conversely, the proportion of reefs that were severely bleached (>60% of corals affected) was four times higher in 2016. The geographic footprint of each of the three events is distinctive, and matches satellite-derived sea surface

  20. Remote monitoring of chlorophyll fluorescence in two reef corals during the 2005 bleaching event at Lee Stocking Island, Bahamas

    Science.gov (United States)

    Manzello, D.; Warner, M.; Stabenau, E.; Hendee, J.; Lesser, M.; Jankulak, M.

    2009-03-01

    Zooxanthellae fluorescence was measured in situ, remotely, and in near real-time with a pulse amplitude modulated (PAM) fluorometer for a colony of Siderastrea siderea and Agaricia tenuifolia at Lee Stocking Island, Bahamas during the Caribbean-wide 2005 bleaching event. These colonies displayed evidence of photosystem II (PS II) inactivation coincident with thermal stress and seasonally high doses of solar radiation. Hurricane-associated declines in temperature and light appear to have facilitated the recovery of maximum quantum yield of PS II within these two colonies, although both corals responded differently to individual storms. PAM fluorometry, coupled with long-term measurement of in situ light and temperature, provides much more detail of coral photobiology on a seasonal time scale and during possible bleaching conditions than sporadic, subjective, and qualitative observations. S. siderea displayed evidence of PS II inactivation over a month prior to the issuing of a satellite-based, sea surface temperature (SST) bleaching alert by the National Oceanic and Atmospheric Administration (NOAA). In fact, recovery had already begun in S. siderea when the bleaching alert was issued. Fluorescence data for A. tenuifolia were difficult to interpret because the shaded parts of a colony were monitored and thus did not perfectly coincide with thermal stress and seasonally high doses of solar radiation as in S. siderea. These results further emphasize the limitations of solely monitoring SST (satellite or in situ) as a bleaching indicator without considering the physiological status of coral-zooxanthellae symbioses.

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

    Science.gov (United States)

    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

  2. Coral mass bleaching and reef temperatures at Navassa Island, 2006

    Science.gov (United States)

    Miller, M. W.; Piniak, G. A.; Williams, D. E.

    2011-01-01

    Bleaching and associated mortality is an extreme threat to the persistence of coral populations in the projected warming regime of the next few decades. Recent evidence indicates that thermal bleaching thresholds may be affected by water quality gradients. The unexpected encounter of a coral mass bleaching event at a remote, uninhabited Caribbean island (Navassa) during a routine reef assessment cruise in November 2006 provided the opportunity to characterize bleaching responses and thermal exposure in an oceanic area with negligible continental influence or human impact on water quality. The coral taxa most susceptible to bleaching were Agaricia spp. and Montastraea faveolata. Siderastraea siderea, Diploria spp. and Porites porites were intermediately affected, while Porites astreoides and Montastraea cavernosa were minimally affected and negligible bleaching was observed in Acropora palmata. Bleaching prevalence (colonies > 4 cm diameter) ranged from 0.16 to 0.63 among sites. Deeper sites (between 18 and 37 m) had significantly higher prevalence of bleaching than shallow sites (<10 m). This general pattern of more bleaching in deeper sites also occurred within species. Though exposure to high-temperature stress was not greater at deeper sites, water motion, which may bolster bleaching resistance, was likely less. In situ loggers indicated temperatures over 30 °C initiated at shallow sites in mid-August, at deeper sites in early September, and were persistent at all sites until mid-October. Long term (1983-2007) climatologies constructed from AVHRR SSTs suggest that the mass bleaching event observed at Navassa in 2006 corresponded with greater intensity and duration of warm temperature anomalies than occurred in 2005, for which no in situ observations (bleaching nor temperature) are available.

  3. Depth-dependent mortality of reef corals following a severe bleaching event: implications for thermal refuges and population recovery [v3; ref status: indexed, http://f1000r.es/2zg

    Directory of Open Access Journals (Sweden)

    Tom C. L. Bridge

    2014-02-01

    Full Text Available 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.

  4. Depth-dependent mortality of reef corals following a severe bleaching event: implications for thermal refuges and population recovery [v2; ref status: indexed, http://f1000r.es/26m

    Directory of Open Access Journals (Sweden)

    Tom C. L. Bridge

    2013-10-01

    Full Text Available 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.

  5. Reef corals bleach to resist stress.

    Science.gov (United States)

    Obura, David O

    2009-02-01

    A rationale is presented here for a primary role of bleaching in regulation of the coral-zooxanthellae symbiosis under conditions of stress. Corals and zooxanthellae have fundamentally different metabolic rates, requiring active homeostasis to limit zooxanthellae production and manage translocated products to maintain the symbiosis. The control processes for homeostasis are compromised by environmental stress, resulting in metabolic imbalance between the symbionts. For the coral-zooxanthella symbiosis the most direct way to minimize metabolic imbalance under stress is to reduce photosynthetic production by zooxanthellae. Two mechanisms have been demonstrated that do this: reduction of the chlorophyll concentration in individual zooxanthellae and reduction of the relative biomass of zooxanthellae. Both mechanisms result in visual whitening of the coral, termed bleaching. Arguments are presented here that bleaching provides the final control to minimize physiological damage from stress as an adversity response to metabolic imbalance. As such, bleaching meets the requirements of a stress response syndrome/general adaptive mechanism that is sensitive to internal states rather than external parameters. Variation in bleaching responses among holobionts reflects genotypic and phenotypic differentiation, allowing evolutionary change by natural selection. Thus, reef corals bleach to resist stress, and thereby have some capacity to adapt to and survive change. The extreme thermal anomalies causing mass coral bleaching worldwide lie outside the reaction norms for most coral-zooxanthellae holobionts, revealing the limitations of bleaching as a control mechanism.

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

    OpenAIRE

    Dishon, G.; Fisch, J.; Horn, Ingo; Kaczmarek, Karina; Bijma, Jelle; Gruber, D.F.; Nir, O.; Popovich, Y.; Tchernov, D.

    2015-01-01

    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 ex...

  7. Post-bleaching coral community change on southern Maldivian reefs: is there potential for rapid recovery?

    Science.gov (United States)

    Perry, C. T.; Morgan, K. M.

    2017-12-01

    Given the severity of the 2016 global bleaching event, there are major questions about how quickly reef communities will recover. Here, we explore the ecological and physical structural changes that occurred across five atoll interior reefs in the southern Maldives using data collected at 6 and 12 months post-bleaching. Following initial severe coral mortality, further minor coral mortality had occurred by 12 months post-bleaching, and coral cover is now low (transitions to rubble-dominated states will occur in the near future. Juvenile coral densities in shallow fore-reef habitats are also exceptionally low (<6 individuals m-2), well below those measured 9-12 months following the 1998 bleaching event, and below recovery thresholds identified on other Indian Ocean reefs. Our findings suggest that the physical structure of these reefs will need to decline further before effective recruitment and recovery can begin.

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

    KAUST Repository

    Furby, Kathryn A.

    2013-01-04

    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. © 2013 Springer-Verlag Berlin Heidelberg.

  9. Correlation of Coral Bleaching Events and Remotely-Sensed Sea Surface Temperatures

    Science.gov (United States)

    1994-05-19

    water column. Diving on the reefs, they found significant tracts of bleached corals, zoanthids , gorgonians, and sea anemones (Bunckley-Williams and... zoanthids between May and July 1988 on shallow lagoonal reefs and rim margin reefs was the first indication of any sort of bleaching event at Bermuda

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

    Science.gov (United States)

    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. Copyright © 2016, American Association for the Advancement of Science.

  11. Severity of the 1998 and 2005 bleaching events in Venezuela, southern Caribbean

    Directory of Open Access Journals (Sweden)

    Sebastián Rodríguez

    2010-10-01

    Full Text Available This study describes the severity of the 2005 bleaching event at 15 reef sites across Venezuela and compares the 1998 and 2005 bleaching events at one of them. During August and September 2005, bleached corals were first observed on oceanic reefs rather than coastal reefs, affecting 1 to 4% of coral colonies in the community (3 reef sites, n=736 colonies. At that time, however, no bleached corals were recorded along the eastern coast of Venezuela, an area of seasonal upwelling (3 reefs, n=181 colonies. On coastal reefs, bleaching started in October but highest levels were reached in November 2005 and January 2006, when 16% of corals were affected among a wide range of taxa (e.g. scleractinians, octocorals, Millepora and zoanthids. In the Acropora habitats of Los Roques (an oceanic reef, no bleached was recorded in 2005 (four sites, n=643 colonies. At Cayo Sombrero, a coastal reef site, bleaching was less severe in 1998 than in 2005 (9% of the coral colonies involving 2 species vs. 26% involving 23 species, respectively. Our results indicate that bleaching was more severe in 2005 than in 1998 on Venezuelan reefs; however, no mass mortality was observed in either of these two events. Rev. Biol. Trop. 58 (Suppl. 3: 189-196. Epub 2010 October 01.

  12. Severity of the 1998 and 2005 bleaching events in Venezuela, southern Caribbean.

    Science.gov (United States)

    Rodríguez, Sebastián; Cróquer, Aldo; Bone, David; Bastidas, Carolina

    2010-10-01

    This study describes the severity of the 2005 bleaching event at 15 reef sites across Venezuela and compares the 1998 and 2005 bleaching events at one of them. During August and September 2005, bleached corals were first observed on oceanic reefs rather than coastal reefs, affecting 1 to 4% of coral colonies in the community (3 reef sites, n = 736 colonies). At that time, however, no bleached corals were recorded along the eastern coast of Venezuela, an area of seasonal upwelling (3 reefs, n = 181 colonies). On coastal reefs, bleaching started in October but highest levels were reached in November 2005 and January 2006, when 16% of corals were affected among a wide range of taxa (e.g. scleractinians, octocorals, Millepora and zoanthids). In the Acropora habitats of Los Roques (an oceanic reef),no bleached was recorded in 2005 (four sites,n = 643 colonies). At Cayo Sombrero, a coastal reef site, bleaching was less severe in 1998 than in 2005 (9% of the coral colonies involving 2 species vs. 26% involving 23 species, respectively). Our results indicate that bleaching was more severe in 2005 than in 1998 on Venezuelan reefs; however, no mass mortality was observed in either of these two events.

  13. Predicting Heat Stress to Inform Reef Management: NOAA Coral Reef Watch's 4-Month Coral Bleaching Outlook

    Directory of Open Access Journals (Sweden)

    Gang Liu

    2018-03-01

    Full Text Available The U.S. National Oceanic and Atmospheric Administration's (NOAA Coral Reef Watch (CRW operates a global 4-Month Coral Bleaching Outlook system for shallow-water coral reefs in collaboration with NOAA's National Centers for Environmental Prediction (NCEP. The Outlooks are generated by applying the algorithm used in CRW's operational satellite coral bleaching heat stress monitoring, with slight modifications, to the sea surface temperature (SST predictions from NCEP's operational Climate Forecast System Version 2 (CFSv2. Once a week, the probability of heat stress capable of causing mass coral bleaching is predicted for 4-months in advance. Each day, CFSv2 generates an ensemble of 16 forecasts, with nine runs out to 45-days, three runs out to 3-months, and four runs out to 9-months. This results in 28–112 ensemble members produced each week. A composite for each predicted week is derived from daily predictions within each ensemble member. The probability of each of four heat stress ranges (Watch and higher, Warning and higher, Alert Level 1 and higher, and Alert Level 2 is determined from all the available ensemble members for the week to form the weekly probabilistic Outlook. The probabilistic 4-Month Outlook is the highest weekly probability predicted among all the weekly Outlooks during a 4-month period for each of the stress ranges. An initial qualitative skill analysis of the Outlooks for 2011–2015, compared with CRW's satellite-based coral bleaching heat stress products, indicated the Outlook has performed well with high hit rates and low miss rates for most coral reef areas. Regions identified with high false alarm rates will guide future improvements. This Outlook system, as the first and only freely available global coral bleaching prediction system, has been providing critical early warning to marine resource managers, scientists, and decision makers around the world to guide management, protection, and monitoring of coral reefs

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

    Science.gov (United States)

    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

  15. Species identity and depth predict bleaching severity in reef-building corals: shall the deep inherit the reef?

    Science.gov (United States)

    Muir, Paul R; Marshall, Paul A; Abdulla, Ameer; Aguirre, J David

    2017-10-11

    Mass bleaching associated with unusually high sea temperatures represents one of the greatest threats to corals and coral reef ecosystems. Deeper reef areas are hypothesized as potential refugia, but the susceptibility of Scleractinian species over depth has not been quantified. During the most severe bleaching event on record, we found up to 83% of coral cover severely affected on Maldivian reefs at a depth of 3-5 m, but significantly reduced effects at 24-30 m. Analysis of 153 species' responses showed depth, shading and species identity had strong, significant effects on susceptibility. Overall, 73.3% of the shallow-reef assemblage had individuals at a depth of 24-30 m with reduced effects, potentially mitigating local extinction and providing a source of recruits for population recovery. Although susceptibility was phylogenetically constrained, species-level effects caused most lineages to contain some partially resistant species. Many genera showed wide variation between species, including Acropora, previously considered highly susceptible. Extinction risk estimates showed species and lineages of concern and those likely to dominate following repeated events. Our results show that deeper reef areas provide refuge for a large proportion of Scleractinian species during severe bleaching events and that the deepest occurring individuals of each population have the greatest potential to survive and drive reef recovery. © 2017 The Author(s).

  16. Coral bleaching on high-latitude marginal reefs at Sodwana Bay, South Africa

    International Nuclear Information System (INIS)

    Celliers, Louis; Schleyer, Michael H.

    2002-01-01

    Coral bleaching, involving the expulsion of symbiotic zooxanthellae from the host cells, poses a major threat to coral reefs throughout their distributional range. The role of temperature in coral bleaching has been extensively investigated and is widely accepted. A bleaching event was observed on the marginal high-latitude reefs of South Africa located at Sodwana Bay during the summer months of 2000. This was associated with increased sea temperatures with high seasonal peaks in summer and increased radiation in exceptionally clear water. The bleaching was limited to Two-mile Reef and Nine-mile Reef at Sodwana Bay and affected -1 from May 1994 to April 2000. High maximum temperatures were measured (>29 deg. C). The lowest mean monthly and the mean maximum monthly temperatures at which coral bleaching occurred were 27.5 and 28.8 deg. C, respectively, while the duration for which high temperatures occurred in 2000 was 67 days at ≥27.5 deg. C (4 days at ≥28.8 deg. C). Increased water clarity and radiation appeared to be a synergistic cause in the coral bleaching encountered at Sodwana Bay

  17. Warming Trends and Bleaching Stress of the World’s Coral Reefs 1985-2012

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    Science.gov (United States)

    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.

  20. Contrasting patterns of changes in abundance following a bleaching event between juvenile and adult scleractinian corals

    Science.gov (United States)

    Álvarez-Noriega, Mariana; Baird, Andrew H.; Bridge, Tom C. L.; Dornelas, Maria; Fontoura, Luisa; Pizarro, Oscar; Precoda, Kristin; Torres-Pulliza, Damaris; Woods, Rachael M.; Zawada, Kyle; Madin, Joshua S.

    2018-06-01

    Coral bleaching events have caused extensive mortality on reefs around the world. Juvenile corals are generally less affected by bleaching than their conspecific adults and therefore have the potential to buffer population declines and seed recovery. Here, we use juvenile and adult abundance data at 20 sites encircling Lizard Island, Great Barrier Reef, before and after the 2016 bleaching event to quantify: (1) correlates of changes in juvenile abundance following a bleaching event; (2) differences in susceptibility to extreme thermal stress between juveniles and adults. Declines in juvenile abundance were lower at sites closer to the 20-m-depth contour and higher for Acropora and Pocillopora juveniles than for other taxa. Juveniles of Acropora and Goniastrea were less susceptible to bleaching than adults, but the opposite was true for Pocillopora spp. and taxa in the family Merulinidae. Our results indicate that the potential of the juvenile life stage to act as a buffer during bleaching events is taxon-dependent.

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

    Science.gov (United States)

    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 ...

  2. Coral bleaching on high-latitude marginal reefs at Sodwana Bay, South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Celliers, Louis; Schleyer, Michael H

    2002-12-01

    Coral bleaching, involving the expulsion of symbiotic zooxanthellae from the host cells, poses a major threat to coral reefs throughout their distributional range. The role of temperature in coral bleaching has been extensively investigated and is widely accepted. A bleaching event was observed on the marginal high-latitude reefs of South Africa located at Sodwana Bay during the summer months of 2000. This was associated with increased sea temperatures with high seasonal peaks in summer and increased radiation in exceptionally clear water. The bleaching was limited to Two-mile Reef and Nine-mile Reef at Sodwana Bay and affected <12% of the total living cover on Two-mile Reef. Montipora spp., Alveopora spongiosa and Acropora spp. were bleached, as well as some Alcyoniidae (Sinularia dura, Lobophytum depressum, L. patulum). A cyclical increase in sea temperature (with a period of 5-6 years) was recorded during 1998-2000 in addition to the regional temperature increase caused by the El Nino Southern Oscillation phenomenon. The mean sea temperature increased at a rate of 0.27 deg. C year{sup -1} from May 1994 to April 2000. High maximum temperatures were measured (>29 deg. C). The lowest mean monthly and the mean maximum monthly temperatures at which coral bleaching occurred were 27.5 and 28.8 deg. C, respectively, while the duration for which high temperatures occurred in 2000 was 67 days at {>=}27.5 deg. C (4 days at {>=}28.8 deg. C). Increased water clarity and radiation appeared to be a synergistic cause in the coral bleaching encountered at Sodwana Bay.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  6. Mass coral bleaching causes biotic homogenization of reef fish assemblages.

    Science.gov (United States)

    Richardson, Laura E; Graham, Nicholas A J; Pratchett, Morgan S; Eurich, Jacob G; Hoey, Andrew S

    2018-04-06

    Global climate change is altering community composition across many ecosystems due to nonrandom species turnover, typically characterized by the loss of specialist species and increasing similarity of biological communities across spatial scales. As anthropogenic disturbances continue to alter species composition globally, there is a growing need to identify how species responses influence the establishment of distinct assemblages, such that management actions may be appropriately assigned. Here, we use trait-based analyses to compare temporal changes in five complementary indices of reef fish assemblage structure among six taxonomically distinct coral reef habitats exposed to a system-wide thermal stress event. Our results revealed increased taxonomic and functional similarity of previously distinct reef fish assemblages following mass coral bleaching, with changes characterized by subtle, but significant, shifts toward predominance of small-bodied, algal-farming habitat generalists. Furthermore, while the taxonomic or functional richness of fish assemblages did not change across all habitats, an increase in functional originality indicated an overall loss of functional redundancy. We also found that prebleaching coral composition better predicted changes in fish assemblage structure than the magnitude of coral loss. These results emphasize how measures of alpha diversity can mask important changes in the structure and functioning of ecosystems as assemblages reorganize. Our findings also highlight the role of coral species composition in structuring communities and influencing the diversity of responses of reef fishes to disturbance. As new coral species configurations emerge, their desirability will hinge upon the composition of associated species and their capacity to maintain key ecological processes in spite of ongoing disturbances. © 2018 John Wiley & Sons Ltd.

  7. High-resolution modeling of thermal thresholds and environmental influences on coral bleaching for local and regional reef management.

    Science.gov (United States)

    Kumagai, Naoki H; Yamano, Hiroya

    2018-01-01

    Coral reefs are one of the world's most threatened ecosystems, with global and local stressors contributing to their decline. Excessive sea-surface temperatures (SSTs) can cause coral bleaching, resulting in coral death and decreases in coral cover. A SST threshold of 1 °C over the climatological maximum is widely used to predict coral bleaching. In this study, we refined thermal indices predicting coral bleaching at high-spatial resolution (1 km) by statistically optimizing thermal thresholds, as well as considering other environmental influences on bleaching such as ultraviolet (UV) radiation, water turbidity, and cooling effects. We used a coral bleaching dataset derived from the web-based monitoring system Sango Map Project, at scales appropriate for the local and regional conservation of Japanese coral reefs. We recorded coral bleaching events in the years 2004-2016 in Japan. We revealed the influence of multiple factors on the ability to predict coral bleaching, including selection of thermal indices, statistical optimization of thermal thresholds, quantification of multiple environmental influences, and use of multiple modeling methods (generalized linear models and random forests). After optimization, differences in predictive ability among thermal indices were negligible. Thermal index, UV radiation, water turbidity, and cooling effects were important predictors of the occurrence of coral bleaching. Predictions based on the best model revealed that coral reefs in Japan have experienced recent and widespread bleaching. A practical method to reduce bleaching frequency by screening UV radiation was also demonstrated in this paper.

  8. Bleaching of reef coelenterates in the San Blas Islands, Panama

    Science.gov (United States)

    Lasker, Howard R.; Peters, Esther C.; Coffroth, Mary Alice

    1984-12-01

    Starting in June 1983, 25 species of hermatypic corals, gorgonians, hydrocorals, anemones and zoanthids in the San Blas Islands, Panama, began showing signs of a loss of colour leading in some cases to a white “bleached” appearance. Histologic examination of six coral species indicated that bleaching was associated with drastic reductions in the density of zooxanthellae and with the atrophy and necrosis of the animal tissue. The severity of the bleaching varied among species and many species were unaffected. The species most extensively affected were: Agaricia spp., which became completely bleached and frequently died; Montastraea annularis which bleached and continued to survive; and Millepora spp. which bleached white but quickly regained their colouration. Shallow reefs dominated by Agaricia spp. suffered the most extensive bleaching. At one site, Pico Feo, 99% of the Agaricia (32% of the living cover) was bleached. On fore reers, which were dominated by Agaricia spp. and M. annularis, the proportion of M. annularis bleached ranged from 18 to 100% and that of Agaricia spp. from 30 to 53%. Transects at Sail Rock and House Reef were surveyed in August 1983 and January 1984. At those sites, 53% of the Agaricia cover died between August and January. The remaining living cover of Agaricia and of all other species exhibited normal colouration in January. Salinity and temperature were monitored every second day at 4 m depth between May 10 and August 28, 1983 at one of the localities. Bleaching was first observed within two weeks of a 2 °C rise in temperature which occurred in late May 1983. Temperatures remained at or above 31.5 °C for the following 3 weeks and were at or above 30 °C for an additional 4 weeks. The bleaching of corals in the San Blas was most likely due to those elevanted temperatures.

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

    Science.gov (United States)

    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.

  10. In situ observations of coral bleaching in the central Saudi Arabian Red Sea during the 2015/2016 global coral bleaching event.

    Science.gov (United States)

    Monroe, Alison A; Ziegler, Maren; Roik, Anna; Röthig, Till; Hardenstine, Royale S; Emms, Madeleine A; Jensen, Thor; Voolstra, Christian R; Berumen, Michael L

    2018-01-01

    Coral bleaching continues to be one of the most devastating and immediate impacts of climate change on coral reef ecosystems worldwide. In 2015, a major bleaching event was declared as the "3rd global coral bleaching event" by the United States National Oceanic and Atmospheric Administration, impacting a large number of reefs in every major ocean. The Red Sea was no exception, and we present herein in situ observations of the status of coral reefs in the central Saudi Arabian Red Sea from September 2015, following extended periods of high temperatures reaching upwards of 32.5°C in our study area. We examined eleven reefs using line-intercept transects at three different depths, including all reefs that were surveyed during a previous bleaching event in 2010. Bleaching was most prevalent on inshore reefs (55.6% ± 14.6% of live coral cover exhibited bleaching) and on shallower transects (41% ± 10.2% of live corals surveyed at 5m depth) within reefs. Similar taxonomic groups (e.g., Agariciidae) were affected in 2015 and in 2010. Most interestingly, Acropora and Porites had similar bleaching rates (~30% each) and similar relative coral cover (~7% each) across all reefs in 2015. Coral genera with the highest levels of bleaching (>60%) were also among the rarest (coral cover) in 2015. While this bodes well for the relative retention of coral cover, it may ultimately lead to decreased species richness, often considered an important component of a healthy coral reef. The resultant long-term changes in these coral reef communities remain to be seen.

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

    Science.gov (United States)

    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.

  12. Response of millepora alcicornis (Milleporina: Milleporidae) to two bleaching enventgs at Puerto Morelos reef, Mexican Caribbean

    International Nuclear Information System (INIS)

    Banaszak, A.T.; Ayala Schiaffino, B.N.; Rodriguez Roman, A.; Enriquez, S.; Iglesias Prieto, R.

    2003-01-01

    Two naturally occurring colonies of Millepora alcicornis were monitored during 1997 and 1998, both years in which this species bleached in the Mexican Caribbean. One colony (HL) was naturally exposed to a high light environment and another nearby colony (LL) was exposed to 5.9 times lower light levels due to shadowing by a pier. For 10 days in August 1997, seawater temperatures in the surrounding reef lagoon rose up to 1.5 degrees C above the 6-year August average. The HL colony bleached to white during this period, whereas, the LL colony remained dark-brown colored. The HL colony recovered its normal dark-brown coloration (reversible bleaching) within several weeks, during which time the seawater temperatures returned to average. The following year, for 10 days, seawater temperatures rose up to 3 degrees C above the 7-year August average and both colonies bleached to white and neither colony recovered (irreversible bleaching). Both colonies were rapidly overgrown by algae and hydroids and, as of June 2003, no recovery has taken place. Prior to the 1997 bleaching, experiments using solar radiation showed that the quantum yield of photosystem II charge separation of branches from HL and LL colonies were affected for several hours by exposure to ultraviolet radiation (UVR, 280 to 400 nm), but recovered by the same evening, suggesting that UVR does not have long-term effects on photochemistry in M. alcicornis. In situ effective quantum yield of photosystem II charge separation (ΔF/Fm ' ) measurements before the 1998 bleaching event indicate that both colonies were healthy in terms of the physiological status of their endosymbionts. During and after the 1998 bleaching event, both colonies showed a reduction in ΔF/Fm ' and consequently an increase in excitation pressure on photosystem II. The data suggest that temperature is not the only factor that causes bleaching and that solar radiation may play an important role in coral bleaching. (Author)

  13. Is climate change triggering coral bleaching in tropical reef?

    Digital Repository Service at National Institute of Oceanography (India)

    Kalyan, De; Sautya, S.; Mote, S.; Tsering, L.; Patil, V.; Nagesh, R.; Ingole, B.S.

    established a herbarium at the Marine Algal Re- search Station, Mandapam Camp in April 2015. The old marine algal herbarium collection has been refurbished and des- ignated as reference repository at the na- tional level. This unique facility holds over... assessment of coral bleaching. Four belt transects (50 m  2 m) were deployed2 at a depth of 3–6 m, covering a total area of 400 m2 each of the sub-tidal reef flat (Figure 1). We have estimated mean bleaching of 15% coral colonies in the area sur...

  14. Coral diseases and bleaching on Colombian Caribbean coral reefs

    Directory of Open Access Journals (Sweden)

    Raúl Navas-Camacho

    2010-05-01

    Full Text Available 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 (10x2m 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

  15. Skeletal light-scattering accelerates bleaching response in reef-building corals.

    Science.gov (United States)

    Swain, Timothy D; DuBois, Emily; Gomes, Andrew; Stoyneva, Valentina P; Radosevich, Andrew J; Henss, Jillian; Wagner, Michelle E; Derbas, Justin; Grooms, Hannah W; Velazquez, Elizabeth M; Traub, Joshua; Kennedy, Brian J; Grigorescu, Arabela A; Westneat, Mark W; Sanborn, Kevin; Levine, Shoshana; Schick, Mark; Parsons, George; Biggs, Brendan C; Rogers, Jeremy D; Backman, Vadim; Marcelino, Luisa A

    2016-03-21

    At the forefront of ecosystems adversely affected by climate change, coral reefs are sensitive to anomalously high temperatures which disassociate (bleaching) photosynthetic symbionts (Symbiodinium) from coral hosts and cause increasingly frequent and severe mass mortality events. Susceptibility to bleaching and mortality is variable among corals, and is determined by unknown proportions of environmental history and the synergy of Symbiodinium- and coral-specific properties. Symbiodinium live within host tissues overlaying the coral skeleton, which increases light availability through multiple light-scattering, forming one of the most efficient biological collectors of solar radiation. Light-transport in the upper ~200 μm layer of corals skeletons (measured as 'microscopic' reduced-scattering coefficient, μ'(S,m)), has been identified as a determinant of excess light increase during bleaching and is therefore a potential determinant of the differential rate and severity of bleaching response among coral species. Here we experimentally demonstrate (in ten coral species) that, under thermal stress alone or combined thermal and light stress, low-μ'(S,m) corals bleach at higher rate and severity than high-μ'(S,m) corals and the Symbiodinium associated with low-μ'(S,m) corals experience twice the decrease in photochemical efficiency. We further modelled the light absorbed by Symbiodinium due to skeletal-scattering and show that the estimated skeleton-dependent light absorbed by Symbiodinium (per unit of photosynthetic pigment) and the temporal rate of increase in absorbed light during bleaching are several fold higher in low-μ'(S,m) corals. While symbionts associated with low-[Formula: see text] corals receive less total light from the skeleton, they experience a higher rate of light increase once bleaching is initiated and absorbing bodies are lost; further precipitating the bleaching response. Because microscopic skeletal light-scattering is a robust predictor

  16. ENSO Weather and Coral Bleaching on the Great Barrier Reef, Australia

    Science.gov (United States)

    McGowan, Hamish; Theobald, Alison

    2017-10-01

    The most devastating mass coral bleaching has occurred during El Niño events, with bleaching reported to be a direct result of increased sea surface temperatures (SSTs). However, El Niño itself does not cause SSTs to rise in all regions that experience bleaching. Nor is the upper ocean warming trend of 0.11°C per decade since 1971, attributed to global warming, sufficient alone to exceed the thermal tolerance of corals. Here we show that weather patterns during El Niño that result in reduced cloud cover, higher than average air temperatures and higher than average atmospheric pressures, play a crucial role in determining the extent and location of coral bleaching on the world's largest coral reef system, the World Heritage Great Barrier Reef (GBR), Australia. Accordingly, synoptic-scale weather patterns and local atmosphere-ocean feedbacks related to El Niño-Southern Oscillation (ENSO) and not large-scale SST warming due to El Niño alone and/or global warming are often the cause of coral bleaching on the GBR.

  17. Climate change, coral bleaching and the future of the world's coral reefs

    Energy Technology Data Exchange (ETDEWEB)

    Hoegh-Guldberg, O. [University of Sydney, Sydney, NSW (Australia). School of Biological Sciences

    1999-07-01

    Sea temperatures in many tropical regions have increased by almost 1{degree}C over the past 100 years, and are currently increasing at about 1-2{degree}C per century. Mass coral bleaching has occurred in association with episodes of elevated sea temperatures over the past 20 years and involves the loss of the zooxanthellae following chronic photoinhibition. Mass bleaching has resulted in significant losses of live coral in many parts of the world. This paper considers the biochemical, physiological and ecological perspectives of coral bleaching. It also uses the outputs of four runs from three models of global climate change which simulate changes in sea temperature and hence how the frequency and intensity of bleaching events will change over the next 100 years. The results suggest that the thermal tolerances of reef-building corals are likely to be exceeded every year within the next few decades. Events as severe as the 1998 event, the worst on record, are likely to become commonplace within 20 years. Most information suggests that the capacity for acclimation by corals has already been exceeded, and that adaptation will be too slow to avert a decline in the quality of the world's reefs.

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

    Science.gov (United States)

    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

  19. Trade-offs in disease and bleaching susceptibility among two color morphs of the Hawaiian reef coral, Montipora capitata

    Science.gov (United States)

    Shore-Maggio, Amanda; Callahan, Sean M.; Aeby, Greta S.

    2018-06-01

    Two threats impacting coral reefs are bleaching and disease, and differential susceptibility to both exists among and within coral taxa. Bleaching resistance is commonly linked to the clade of endosymbiotic Symbiodinium, but may come at a cost to other biological traits. Montipora capitata is an Indo-Pacific reef-building coral with two color morphs, red and orange, which harbor different clades of Symbiodinium. We explored whether these color morphs displayed differences in bleaching/disease susceptibility and other biological traits (growth rate, reproductive output, and lipid content). We found a trade-off between disease and bleaching susceptibility. The orange morph had significantly higher disease prevalence, whereas the red morph had significantly higher bleaching prevalence. Thermal stress experiments found that bleaching and loss of photochemical efficiency occurred significantly faster in the red morph, but at normal temperatures, the red morph had a significantly higher growth rate. Higher abundance of the red morph in the field suggests that disease resistance is a more successful strategy in the absence of thermal stress events. The orange morph may better tolerate increases in sea temperatures, but may not persist due to decreased growth rate and increased disease susceptibility. Trade-offs in response to stressors highlight the need to consider local and global threats to coral reefs.

  20. Massive hard coral loss after a severe bleaching event in 2010 at Los Roques, Venezuela

    Directory of Open Access Journals (Sweden)

    Carolina Bastidas

    2012-03-01

    Full Text Available Thermal anomalies have become more severe, frequent and well-documented across the Caribbean for the past 30 years. This increase in temperature has caused coral bleaching resulting in reef decline. At Los Roques National Park, Venezuela, temperature has been monitored at four reef sites. In mid-September 2010, seawater temperature reached 30.85°C at 5 m depth in Los Roques, an archipelago only slightly affected by previous bleaching events. For example, bleaching in Los Roques in 2005 was mild compared to the rest of the Caribbean and to the results in this study. In 2010, seawater temperatures remained above 29.0°C from mid-August until the first week of November, resulting in +16 Degree Heating Weeks by that time. Our annual survey of four reef sites indicated that 72% of 563 scleractinian colonies were partial or totally bleached (white or pale (discolored in October 2010. In February 2011, there were still 46% of coral colonies affected; but most of them were pale and only 2% were bleached. By February, coral cover had declined 4 to 30% per transect, with a mean of 14.3%. Thus, mean coral cover dropped significantly from 45 to 31% cover (a 34% reduction. In addition to bleaching, corals showed a high prevalence (up to 16% of black band disease in October 2010 and of white plague (11% in February 2011. As a consequence, coral mortality is expected to be larger than reported here. Reef surveys since 2002 and personal observations for more than 20 years indicated that this bleaching event and its consequences in Los Roques have no precedent. Our results suggest that reef sites with no previous record of significant deterioration are more likely to become affected by thermal anomalies. However, this archipelago is relatively unaffected by local anthropogenic disturbance and has a high coral recruitment, which may contribute to its recovery

  1. Topography and spatial arrangement of reef-building corals on the fringing reefs of North Jamaica may influence their response to disturbance from bleaching.

    Science.gov (United States)

    Crabbe, M J C

    2010-04-01

    Knowledge of factors that are important in reef resilience helps us understand how reefs react following major environmental disturbances such as hurricanes and bleaching. Here we test factors that might have influenced Jamaican reef resilience to, and subsequent recovery from, the 2005 bleaching event, and which might help inform management policy for reefs in the future: reef rugosity and contact of corals with macroalgae. In addition, we test in the field, on Dairy Bull reef, whether aggregated Porites astreoides colonies exhibit enhanced growth when exposed to superior competition from Acopora palmata, as has been found by experiment with the Indo-Pacific corals Porites lobata and the superior competitor Porites rus [Idjadi, J.A., Karlson, R.H., 2007. Spatial arrangement of competitors influences coexistence of reef-building corals. Ecology 88, 2449-2454]. There were significant linear relationships between rugosity and the increase in smallest size classes for Sidastrea siderea, Colpophyllia natans, P. astreoides and Agaricia species, and between rugosity and cover of the branching coral Acropora cervicornis. Linear extension rates of A. cervicornis and radial growth rates of P. astreoides were significantly lower (p6) when in contact with macroalgae. Aggregated colonies of P. astreoides in contact with one another, one of which was in contact with the faster growing competitor A. palmata showed significantly greater growth rates than with just two aggregated P. astreoides colonies alone. These findings suggest that three dimensional topography and complexity is important for reef resilience and viability in the face of environmental stressors such as bleaching. Our findings also support the idea that aggregated spatial arrangements of corals can influence the outcome of interspecific competition and promote species coexistence, important in times of reef recovery after disturbance. Copyright 2009 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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. © 2013 John Wiley & Sons Ltd.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  5. Coral diseases and bleaching on Colombian Caribbean coral reefs

    Directory of Open Access Journals (Sweden)

    Raúl Navas-Camacho

    2010-05-01

    Full Text Available 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 (10x2m 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

  6. NOAA's Coral Reef Conservation Program: 2016 Projects Monitoring the Effects of Thermal Stress on Coral Bleaching

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Climate change impacts have been identified as one of the greatest global threats to coral reef ecosystems. As temperature rise, mass bleaching, and infectious...

  7. Non-bleached colonies of massive Porites may attract fishes for selective grazing during mass bleaching events

    Directory of Open Access Journals (Sweden)

    Eri Ikeuchi

    2017-06-01

    Full Text Available In this study we investigated the variation in grazing scar densities between bleached and non-bleached colonies of massive Porites species in Sekisei Lagoon (Okinawa, southwestern Japan during a mass bleaching event in 2016. The grazing scar densities and bleaching susceptibility varied among neighboring colonies of massive Porites spp. However, non-bleached colonies had significantly more surface scars than bleached colonies. One explanation for these variations is that corallivorous fishes may selectively graze on non-bleached, thermally tolerant colonies. This is the first report of a relationship between grazing scars and the bleaching status of massive Porites spp. colonies during a mass bleaching event.

  8. Mortality, recovery, and community shifts of scleractinian corals in Puerto Rico one decade after the 2005 regional bleaching event

    Directory of Open Access Journals (Sweden)

    Jorge R. García-Sais

    2017-07-01

    Full Text Available This work analyzes the mortality, recovery, and shifts in the composition of scleractinian corals from Puerto Rico one decade after the 2005 regional coral bleaching event. Temporal and spatial patterns of coral community structure were examined using a stratified, non-random sampling approach based on five permanent transects per reef at 16 reef stations. A negative correlation between percent coral cover loss and light attenuation coefficient (Kd490 was observed, suggesting that light attenuation, as influenced by water turbidity and depth, played a major role in coral protection during the bleaching event (“sunblock effect”. Responses of coral assemblages varied after the bleaching event, including shifts of cover from massive corals (Orbicella spp. to opportunistic (Porites astreoides and branching corals (Madracis auretenra, P. porites and/or turf algae; partial recovery of reef substrate cover by O. annularis complex; and no measurable changes in coral assemblages before and after the event.

  9. Mortality, recovery, and community shifts of scleractinian corals in Puerto Rico one decade after the 2005 regional bleaching event.

    Science.gov (United States)

    García-Sais, Jorge R; Williams, Stacey M; Amirrezvani, Ali

    2017-01-01

    This work analyzes the mortality, recovery, and shifts in the composition of scleractinian corals from Puerto Rico one decade after the 2005 regional coral bleaching event. Temporal and spatial patterns of coral community structure were examined using a stratified, non-random sampling approach based on five permanent transects per reef at 16 reef stations. A negative correlation between percent coral cover loss and light attenuation coefficient (Kd 490 ) was observed, suggesting that light attenuation, as influenced by water turbidity and depth, played a major role in coral protection during the bleaching event ("sunblock effect"). Responses of coral assemblages varied after the bleaching event, including shifts of cover from massive corals ( Orbicella spp.) to opportunistic ( Porites astreoides ) and branching corals ( Madracis auretenra , P. porites ) and/or turf algae; partial recovery of reef substrate cover by O. annularis complex; and no measurable changes in coral assemblages before and after the event.

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

    Science.gov (United States)

    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

  11. Monitoring Coral Health to Determine Coral Bleaching Response at High Latitude Eastern Australian Reefs: An Applied Model for A Changing Climate

    Directory of Open Access Journals (Sweden)

    Andrew G. Carroll

    2011-09-01

    Full Text Available Limited information is available on the bleaching susceptibility of coral species that dominate high latitude reefs along the eastern seaboard of Australia. The main aims of this study were to: (i monitor coral health and spatial patterns of coral bleaching response at the Solitary Islands Marine Park (SIMP and Lord Howe Island Marine Park (LHIMP, to determine variability of bleaching susceptibility among coral taxa; (ii predict coral bleaching thresholds at 30 °S and 31.5 °S, extrapolated from published bleaching threshold data; and (iii propose a subtropical northern New South Wales coral bleaching model from biological and physical data. Between 2005 and 2007 minor bleaching was observed in dominant coral families including Pocilloporidae, Poritidae and Dendrophylliidae in the SIMP and Pocilloporidae, Poritidae and Acroporidae (Isopora and Montipora spp. in the LHIMP, with a clear difference in bleaching susceptibility found between sites, both within and between locations. Bleaching susceptibility was highest in Porites spp. at the most offshore island site within the SIMP during summer 2005. Patterns of subtropical family bleaching susceptibility within the SIMP and LHIMP differed to those previously reported for the central Great Barrier Reef (GBR. These differences may be due to a number of factors, including temperature history and/or the coral hosts association with different zooxanthellae clades, which may have lower thermal tolerances. An analysis of published estimates of coral bleaching thresholds from the Caribbean, South Africa, GBR and central and northern Pacific regions suggests that the bleaching threshold at 30–31.5 °S ranges between 26.5–26.8 °C. This predicted threshold was confirmed by an extensive coral bleaching event on the world’s southernmost coral reef at Lord Howe Island, during the 2010 austral summer season. These results imply that dominant coral taxa at subtropical reefs along the eastern Australian

  12. Turning up the heat: increasing temperature and coral bleaching at the high latitude coral reefs of the Houtman Abrolhos Islands.

    Science.gov (United States)

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

    2012-01-01

    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. 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. 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 edge of its distribution.

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

    Science.gov (United States)

    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. © 2012 Blackwell Publishing Ltd/CNRS.

  14. Severity of the 1998 and 2005 bleaching events in Venezuela, southern Caribbean

    Directory of Open Access Journals (Sweden)

    Sebastián Rodríguez

    2010-10-01

    Full Text Available This study describes the severity of the 2005 bleaching event at 15 reef sites across Venezuela and compares the 1998 and 2005 bleaching events at one of them. During August and September 2005, bleached corals were first observed on oceanic reefs rather than coastal reefs, affecting 1 to 4% of coral colonies in the community (3 reef sites, n=736 colonies. At that time, however, no bleached corals were recorded along the eastern coast of Venezuela, an area of seasonal upwelling (3 reefs, n=181 colonies. On coastal reefs, bleaching started in October but highest levels were reached in November 2005 and January 2006, when 16% of corals were affected among a wide range of taxa (e.g. scleractinians, octocorals, Millepora and zoanthids. In the Acropora habitats of Los Roques (an oceanic reef, no bleached was recorded in 2005 (four sites, n=643 colonies. At Cayo Sombrero, a coastal reef site, bleaching was less severe in 1998 than in 2005 (9% of the coral colonies involving 2 species vs. 26% involving 23 species, respectively. Our results indicate that bleaching was more severe in 2005 than in 1998 on Venezuelan reefs; however, no mass mortality was observed in either of these two events. Rev. Biol. Trop. 58 (Suppl. 3: 189-196. Epub 2010 October 01.En este estudio se describe la severidad del evento de blanqueamiento del 2005 en 15 arrecifes coralinos de Venezuela, y se compara con el ocurrido en 1998 para uno de esos arrecifes. Los primeros corales blanqueados se observaron en agosto y septiembre 2005, en arrecifes oceánicos en lugar de costeros, afectando entre 1 y 4% de las colonias coralinas (3 arrecifes, n= 736 colonias. Para ese momento, tampoco se había detectado blanqueamiento en áreas oceánicas de la costa este de Venezuela (3 arrecifes, n= 181 colonias, donde ocurre una surgencia estacional. En arrecifes costeros, el blanqueamiento comenzó en octubre pero alcanzó su máximo entre noviembre 2005 y enero 2006, afectando hasta el 16% de

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

    Science.gov (United States)

    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. Copyright 2004 Blackwell Publishing Ltd

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

    Science.gov (United States)

    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.

  17. Mass Coral Bleaching in 2010 in the Southern Caribbean

    OpenAIRE

    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 mak...

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

    Science.gov (United States)

    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.

  19. Immune defenses of healthy, bleached and diseased Montastraea faveolata during a natural bleaching event.

    Science.gov (United States)

    Mydlarz, Laura D; Couch, Courtney S; Weil, Ernesto; Smith, Garriet; Harvell, C Drew

    2009-11-16

    One prominent hypothesis regarding climate change and scleractinian corals is that thermal stress compromises immune competence. To test this hypothesis we tracked how the immune defenses of bleached, apparently healthy and yellow band disease (YBD) diseased Montastraea faveolata colonies varied with natural thermal stress in southwestern Puerto Rico. Colonies were monitored for 21 mo from the peak of the bleaching event in October 2005 to August 2007. Since sea surface temperature was significantly higher in summer and fall 2005 than 2006, year of collection was used as a proxy for temperature stress, and colony fragments collected in 2005 were compared with those collected in 2006. Mortality rate was high (43% overall) and all colonies (except one) either died or became infected with YBD by August 2007. YBD-infected tissue did not bleach (i.e. expel zooxanthellae) during the 2005 bleaching event, even when healthy tissue of these colonies bleached. Immune activity was assayed by measuring prophenoloxidase (PPO), peroxidase (POX), lysozyme-like (LYS) and antibacterial (AB) activity. Immune activity was variable between all coral samples, but there was a significant elevation of PPO activity in bleached colonies collected in 2005 relative to apparently healthy and YBD-diseased corals in 2006. In YBD-diseased colonies, LYS and AB activity were elevated in both healthy and infected tissue, indicating a systemic response; activity levels in these colonies were higher compared to those that appeared healthy. In both these immune parameters, there was a trend for suppression of activity in corals that were bleached in 2005. These data, while complicated by between-genet variability, illustrate the complex interaction between disease and temperature stress on immune function.

  20. El Niño, Sea Surface Temperature Anomaly and Coral Bleaching in the South Atlantic: A Chain of Events Modeled With a Bayesian Approach

    Science.gov (United States)

    Lisboa, D. S.; Kikuchi, R. K. P.; Leão, Zelinda M. A. N.

    2018-04-01

    Coral bleaching represents one of the main climate-change related threats to reef ecosystems. This research represents a methodological alternative for modeling this phenomenon, focused on assessing uncertainties and complexities with a low number of observations. To develop this model, intermittent reef monitoring data from the largest reef complex in the South Atlantic collected over nine summers between 2000 and 2014 were used with remote sensing data to construct and train a bleaching seasonal prediction model. The Bayesian approach was used to construct the network as it is suitable for hierarchically organizing local thermal variables and combining them with El Niño indicators from the preceding winter to generate accurate bleaching predictions for the coming season. Network count information from six environmental indicators was used to calculate the probability of bleaching, which is mainly influenced by the combined information of two thermal indices; one thermal index is designed to track short period anomalies in the early summer that are capable of triggering bleaching (SST of five consecutive days), and the other index is responsible for tracking the accumulation of thermal stress over time, an index called degree heating trimester (DHT). In addition to developing the network, this study conducted the three tests of applicability proposed for model: 1- Perform the forecast of coral bleaching for the summer of 2016; 2- Investigate the role of turbidity during the bleaching episodes; and 3- Use the model information to identify areas with a lower predisposition to bleaching events.

  1. Two spatial scales in a bleaching event: Corals from the mildest and the most extreme thermal environments escape mortality

    KAUST Repository

    Pineda, Jesús

    2013-07-28

    In summer 2010, a bleaching event decimated the abundant reef flat coral Stylophora pistillata in some areas of the central Red Sea, where a series of coral reefs 100–300 m wide by several kilometers long extends from the coastline to about 20 km offshore. Mortality of corals along the exposed and protected sides of inner (inshore) and mid and outer (offshore) reefs and in situ and satellite sea surface temperatures (SSTs) revealed that the variability in the mortality event corresponded to two spatial scales of temperature variability: 300 m across the reef flat and 20 km across a series of reefs. However, the relationship between coral mortality and habitat thermal severity was opposite at the two scales. SSTs in summer 2010 were similar or increased modestly (0.5°C) in the outer and mid reefs relative to 2009. In the inner reef, 2010 temperatures were 1.4°C above the 2009 seasonal maximum for several weeks. We detected little or no coral mortality in mid and outer reefs. In the inner reef, mortality depended on exposure. Within the inner reef, mortality was modest on the protected (shoreward) side, the most severe thermal environment, with highest overall mean and maximum temperatures. In contrast, acute mortality was observed in the exposed (seaward) side, where temperature fluctuations and upper water temperature values were relatively less extreme. Refuges to thermally induced coral bleaching may include sites where extreme, high-frequency thermal variability may select for coral holobionts preadapted to, and physiologically condition corals to withstand, regional increases in water temperature.

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

    Science.gov (United States)

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

    2017-11-30

    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. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Excess seawater nutrients, enlarged algal symbiont densities and bleaching sensitive reef locations: 1. Identifying thresholds of concern for the Great Barrier Reef, Australia.

    Science.gov (United States)

    Wooldridge, Scott A

    2016-05-23

    Here, I contribute new insight into why excess seawater nutrients are an increasingly identified feature at reef locations that have low resistance to thermal stress. Specifically, I link this unfavourable synergism to the development of enlarged (suboptimal) zooxanthellae densities that paradoxically limit the capacity of the host coral to build tissue energy reserves needed to combat periods of stress. I explain how both theoretical predictions and field observations support the existence of species-specific 'optimal' zooxanthellae densities ~1.0-3.0×10 6 cellscm- 2 . For the central Great Barrier Reef (GBR), excess seawater nutrients that permit enlarged zooxanthellae densities beyond this optimum range are linked with seawater chlorophyll a>0.45μg·L -1 ; a eutrophication threshold previously shown to correlate with a significant loss in species for hard corals and phototrophic octocorals on the central GBR, and herein shown to correlate with enhanced bleaching sensitivity during the 1998 and 2002 mass bleaching events. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Keisha D. Bahr

    2015-08-01

    Full Text Available 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

  7. Massive hard coral loss after a severe bleaching event in 2010 at Los Roques, Venezuela

    Directory of Open Access Journals (Sweden)

    Carolina Bastidas

    2012-03-01

    Full Text Available Thermal anomalies have become more severe, frequent and well-documented across the Caribbean for the past 30 years. This increase in temperature has caused coral bleaching resulting in reef decline. At Los Roques National Park, Venezuela, temperature has been monitored at four reef sites. In mid-September 2010, seawater temperature reached 30.85°C at 5 m depth in Los Roques, an archipelago only slightly affected by previous bleaching events. For example, bleaching in Los Roques in 2005 was mild compared to the rest of the Caribbean and to the results in this study. In 2010, seawater temperatures remained above 29.0°C from mid-August until the first week of November, resulting in +16 Degree Heating Weeks by that time. Our annual survey of four reef sites indicated that 72% of 563 scleractinian colonies were partial or totally bleached (white or pale (discolored in October 2010. In February 2011, there were still 46% of coral colonies affected; but most of them were pale and only 2% were bleached. By February, coral cover had declined 4 to 30% per transect, with a mean of 14.3%. Thus, mean coral cover dropped significantly from 45 to 31% cover (a 34% reduction. In addition to bleaching, corals showed a high prevalence (up to 16% of black band disease in October 2010 and of white plague (11% in February 2011. As a consequence, coral mortality is expected to be larger than reported here. Reef surveys since 2002 and personal observations for more than 20 years indicated that this bleaching event and its consequences in Los Roques have no precedent. Our results suggest that reef sites with no previous record of significant deterioration are more likely to become affected by thermal anomalies. However, this archipelago is relatively unaffected by local anthropogenic disturbance and has a high coral recruitment, which may contribute to its recoveryDurante las últimas décadas las anomalías térmicas han sido más frecuentes y severas en el Caribe

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

    KAUST Repository

    Furby, Kathryn A.; Bouwmeester, Jessica; Berumen, Michael L.

    2013-01-01

    , 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

  9. Elimination of two reef-building hydrocorals following the 1982-83 El Nino warming event

    Energy Technology Data Exchange (ETDEWEB)

    Glynn, P W; De Weerdt, W H [University of Miami, Miami, FL (USA). Rosenstiel School of Marine and Atmospheric Science, Division of Marine Biology and Fisheries

    1991-07-05

    One probable extinction and one range reduction of eastern Pacific reef-building hydrocoral ({ital Millepora}) species mark the first documented cases of species eliminations resulting from the worldwide 1980s coral reef bleaching events. Two of 12 Panamanian coral species were eliminated suddenly from their former ranges by prolonged high sea temperatures during the 1982-83 El Nino-Southern Oscillation event. Three conditions contributed to their demise: high sensitivity to sea warming, populations confined to a small geographic area, and bathymetric restriction to the euphotic zone ({le}20 meters depth) where El Nino sea warming had its greatest effect.

  10. Marked annual coral bleaching resilience of an inshore patch reef in the Florida Keys: A nugget of hope, aberrance, or last man standing?

    Science.gov (United States)

    Gintert, Brooke E.; Manzello, Derek P.; Enochs, Ian C.; Kolodziej, Graham; Carlton, Renée; Gleason, Arthur C. R.; Gracias, Nuno

    2018-06-01

    Annual coral bleaching events, which are predicted to occur as early as the next decade in the Florida Keys, are expected to cause catastrophic coral mortality. Despite this, there is little field data on how Caribbean coral communities respond to annual thermal stress events. At Cheeca Rocks, an inshore patch reef near Islamorada, FL, the condition of 4234 coral colonies was followed over 2 yr of subsequent bleaching in 2014 and 2015, the two hottest summers on record for the Florida Keys. In 2014, this site experienced 7.7 degree heating weeks (DHW) and as a result 38.0% of corals bleached and an additional 36.6% were pale or partially bleached. In situ temperatures in summer of 2015 were even warmer, with the site experiencing 9.5 DHW. Despite the increased thermal stress in 2015, only 12.1% of corals were bleached in 2015, which was 3.1 times less than 2014. Partial mortality dropped from 17.6% of surveyed corals to 4.3% between 2014 and 2015, and total colony mortality declined from 3.4 to 1.9% between years. Total colony mortality was low over both years of coral bleaching with 94.7% of colonies surviving from 2014 to 2016. The reduction in bleaching severity and coral mortality associated with a second stronger thermal anomaly provides evidence that the response of Caribbean coral communities to annual bleaching is not strictly temperature dose dependent and that acclimatization responses may be possible even with short recovery periods. Whether the results from Cheeca Rocks represent an aberration or a true resilience potential is the subject of ongoing research.

  11. Bleaching and recovery patterns of corals in Palk Bay, India: An indication of bleaching resilient reef

    Digital Repository Service at National Institute of Oceanography (India)

    Manikandan, B.; Ravindran, J.; Vidya, P.J.; ManiMurali, R.

    was calculated corresponding to our observation eight days interval in-situ observations and plotted. PAR is defined as the integration of the solar flux reaching the ocean surface and denoted as Em-2d-1. In this study, PAR data at the ocean surface....11>0.05). Mean SST and PAR was ≤ 30 °C (Mean ± SE) and ≥ 50 Em-2d-1 respectively, during March 2013 (Fig. 2). Coral colonies appeared normal without any signs of bleaching during the first two weeks of March 2013. Favites and Leptastrea colonies were...

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

    Science.gov (United States)

    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.

  13. Global warming and recurrent mass bleaching of corals

    Science.gov (United States)

    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.

  14. Global warming and recurrent mass bleaching of corals.

    Science.gov (United States)

    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.

  15. Changes in biodiversity and functioning of reef fish assemblages following coral bleaching and coral loss

    KAUST Repository

    Pratchett, M.S.; Hoey, A.S.; Wilson, S.K.; Messmer, V.; Graham, N.A.J.

    2011-01-01

    Coral reef ecosystems are increasingly subject to severe, large-scale disturbances caused by climate change (e.g., coral bleaching) and other more direct anthropogenic impacts. Many of these disturbances cause coral loss and corresponding changes in habitat structure, which has further important effects on abundance and diversity of coral reef fishes. Declines in the abundance and diversity of coral reef fishes are of considerable concern, given the potential loss of ecosystem function. This study explored the effects of coral loss, recorded in studies conducted throughout the world, on the diversity of fishes and also on individual responses of fishes within different functional groups. Extensive (>60%) coral loss almost invariably led to declines in fish diversity. Moreover, most fishes declined in abundance following acute disturbances that caused >10% declines in local coral cover. Response diversity, which is considered critical in maintaining ecosystem function and promoting resilience, was very low for corallivores, but was much higher for herbivores, omnivores and carnivores. Sustained and ongoing climate change thus poses a significant threat to coral reef ecosystems and diversity hotspots are no less susceptible to projected changes in diversity and function.

  16. Changes in biodiversity and functioning of reef fish assemblages following coral bleaching and coral loss

    KAUST Repository

    Pratchett, M.S.

    2011-08-12

    Coral reef ecosystems are increasingly subject to severe, large-scale disturbances caused by climate change (e.g., coral bleaching) and other more direct anthropogenic impacts. Many of these disturbances cause coral loss and corresponding changes in habitat structure, which has further important effects on abundance and diversity of coral reef fishes. Declines in the abundance and diversity of coral reef fishes are of considerable concern, given the potential loss of ecosystem function. This study explored the effects of coral loss, recorded in studies conducted throughout the world, on the diversity of fishes and also on individual responses of fishes within different functional groups. Extensive (>60%) coral loss almost invariably led to declines in fish diversity. Moreover, most fishes declined in abundance following acute disturbances that caused >10% declines in local coral cover. Response diversity, which is considered critical in maintaining ecosystem function and promoting resilience, was very low for corallivores, but was much higher for herbivores, omnivores and carnivores. Sustained and ongoing climate change thus poses a significant threat to coral reef ecosystems and diversity hotspots are no less susceptible to projected changes in diversity and function.

  17. Monitoring Coral Health to Determine Coral Bleaching Response at High Latitude Eastern Australian Reefs: An Applied Model for A Changing Climate

    OpenAIRE

    Dalton, Steven J.; Carroll, Andrew G.

    2011-01-01

    Limited information is available on the bleaching susceptibility of coral species that dominate high latitude reefs along the eastern seaboard of Australia. The main aims of this study were to: (i) monitor coral health and spatial patterns of coral bleaching response at the Solitary Islands Marine Park (SIMP) and Lord Howe Island Marine Park (LHIMP), to determine variability of bleaching susceptibility among coral taxa; (ii) predict coral bleaching thresholds at 30 °S and 31.5 °S, extrapolate...

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

    Science.gov (United States)

    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.

  19. Mass Coral Bleaching in 2010 in the Southern Caribbean

    Science.gov (United States)

    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. PMID:24400078

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

    Science.gov (United States)

    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 ...

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Carlos del Mónaco

    2012-06-01

    Full Text Available 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 nonbleached 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 Montastraea faveolata. 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 temperatura reached 31ºC 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. Rev. Biol. Trop. 60 (2

  3. Global patterns and impacts of El Niño events on coral reefs: A meta-analysis.

    Science.gov (United States)

    Claar, Danielle C; Szostek, Lisa; McDevitt-Irwin, Jamie M; Schanze, Julian J; Baum, Julia K

    2018-01-01

    Impacts of global climate change on coral reefs are being amplified by pulse heat stress events, including El Niño, the warm phase of the El Niño Southern Oscillation (ENSO). Despite reports of extensive coral bleaching and up to 97% coral mortality induced by El Niño events, a quantitative synthesis of the nature, intensity, and drivers of El Niño and La Niña impacts on corals is lacking. Herein, we first present a global meta-analysis of studies quantifying the effects of El Niño/La Niña-warming on corals, surveying studies from both the primary literature and International Coral Reef Symposium (ICRS) Proceedings. Overall, the strongest signal for El Niño/La Niña-associated coral bleaching was long-term mean temperature; bleaching decreased with decreasing long-term mean temperature (n = 20 studies). Additionally, coral cover losses during El Niño/La Niña were shaped by localized maximum heat stress and long-term mean temperature (n = 28 studies). Second, we present a method for quantifying coral heat stress which, for any coral reef location in the world, allows extraction of remotely-sensed degree heating weeks (DHW) for any date (since 1982), quantification of the maximum DHW, and the time lag since the maximum DHW. Using this method, we show that the 2015/16 El Niño event instigated unprecedented global coral heat stress across the world's oceans. With El Niño events expected to increase in frequency and severity this century, it is imperative that we gain a clear understanding of how these thermal stress anomalies impact different coral species and coral reef regions. We therefore finish with recommendations for future coral bleaching studies that will foster improved syntheses, as well as predictive and adaptive capacity to extreme warming events.

  4. Global patterns and impacts of El Niño events on coral reefs: A meta-analysis.

    Directory of Open Access Journals (Sweden)

    Danielle C Claar

    Full Text Available Impacts of global climate change on coral reefs are being amplified by pulse heat stress events, including El Niño, the warm phase of the El Niño Southern Oscillation (ENSO. Despite reports of extensive coral bleaching and up to 97% coral mortality induced by El Niño events, a quantitative synthesis of the nature, intensity, and drivers of El Niño and La Niña impacts on corals is lacking. Herein, we first present a global meta-analysis of studies quantifying the effects of El Niño/La Niña-warming on corals, surveying studies from both the primary literature and International Coral Reef Symposium (ICRS Proceedings. Overall, the strongest signal for El Niño/La Niña-associated coral bleaching was long-term mean temperature; bleaching decreased with decreasing long-term mean temperature (n = 20 studies. Additionally, coral cover losses during El Niño/La Niña were shaped by localized maximum heat stress and long-term mean temperature (n = 28 studies. Second, we present a method for quantifying coral heat stress which, for any coral reef location in the world, allows extraction of remotely-sensed degree heating weeks (DHW for any date (since 1982, quantification of the maximum DHW, and the time lag since the maximum DHW. Using this method, we show that the 2015/16 El Niño event instigated unprecedented global coral heat stress across the world's oceans. With El Niño events expected to increase in frequency and severity this century, it is imperative that we gain a clear understanding of how these thermal stress anomalies impact different coral species and coral reef regions. We therefore finish with recommendations for future coral bleaching studies that will foster improved syntheses, as well as predictive and adaptive capacity to extreme warming events.

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

    Digital Repository Service at National Institute of Oceanography (India)

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

    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 Nino in the coral reef bleaching events of the Andaman region. Both Nino 3.4 and 3 indices were...

  6. A global protocol for monitoring of coral bleaching

    OpenAIRE

    Oliver, J.; Setiasih, N.; Marshall, P.; Hansen, L.

    2004-01-01

    Coral bleaching and subsequent mortality represent a major threat to the future health and productivity of coral reefs. However a lack of reliable data on occurrence, severity and other characteristics of bleaching events hampers research on the causes and consequences of this important phenomenon. This article describes a global protocol for monitoring coral bleaching events, which addresses this problem and can be used by people with different levels of expertise and resources.

  7. A new, high-resolution global mass coral bleaching database.

    Directory of Open Access Journals (Sweden)

    Simon D Donner

    Full Text Available Episodes of mass coral bleaching have been reported in recent decades and have raised concerns about the future of coral reefs on a warming planet. Despite the efforts to enhance and coordinate coral reef monitoring within and across countries, our knowledge of the geographic extent of mass coral bleaching over the past few decades is incomplete. Existing databases, like ReefBase, are limited by the voluntary nature of contributions, geographical biases in data collection, and the variations in the spatial scale of bleaching reports. In this study, we have developed the first-ever gridded, global-scale historical coral bleaching database. First, we conducted a targeted search for bleaching reports not included in ReefBase by personally contacting scientists and divers conducting monitoring in under-reported locations and by extracting data from the literature. This search increased the number of observed bleaching reports by 79%, from 4146 to 7429. Second, we employed spatial interpolation techniques to develop annual 0.04° × 0.04° latitude-longitude global maps of the probability that bleaching occurred for 1985 through 2010. Initial results indicate that the area of coral reefs with a more likely than not (>50% or likely (>66% probability of bleaching was eight times higher in the second half of the assessed time period, after the 1997/1998 El Niño. The results also indicate that annual maximum Degree Heating Weeks, a measure of thermal stress, for coral reefs with a high probability of bleaching increased over time. The database will help the scientific community more accurately assess the change in the frequency of mass coral bleaching events, validate methods of predicting mass coral bleaching, and test whether coral reefs are adjusting to rising ocean temperatures.

  8. A new, high-resolution global mass coral bleaching database.

    Science.gov (United States)

    Donner, Simon D; Rickbeil, Gregory J M; Heron, Scott F

    2017-01-01

    Episodes of mass coral bleaching have been reported in recent decades and have raised concerns about the future of coral reefs on a warming planet. Despite the efforts to enhance and coordinate coral reef monitoring within and across countries, our knowledge of the geographic extent of mass coral bleaching over the past few decades is incomplete. Existing databases, like ReefBase, are limited by the voluntary nature of contributions, geographical biases in data collection, and the variations in the spatial scale of bleaching reports. In this study, we have developed the first-ever gridded, global-scale historical coral bleaching database. First, we conducted a targeted search for bleaching reports not included in ReefBase by personally contacting scientists and divers conducting monitoring in under-reported locations and by extracting data from the literature. This search increased the number of observed bleaching reports by 79%, from 4146 to 7429. Second, we employed spatial interpolation techniques to develop annual 0.04° × 0.04° latitude-longitude global maps of the probability that bleaching occurred for 1985 through 2010. Initial results indicate that the area of coral reefs with a more likely than not (>50%) or likely (>66%) probability of bleaching was eight times higher in the second half of the assessed time period, after the 1997/1998 El Niño. The results also indicate that annual maximum Degree Heating Weeks, a measure of thermal stress, for coral reefs with a high probability of bleaching increased over time. The database will help the scientific community more accurately assess the change in the frequency of mass coral bleaching events, validate methods of predicting mass coral bleaching, and test whether coral reefs are adjusting to rising ocean temperatures.

  9. Assessing Coral Response to a Severe Bleaching Event Using Mulimolecular Biomarkers

    Science.gov (United States)

    Babcock-Adams, L.; Minarro, S.; Fitt, W. K.; Medeiros, P. M.

    2016-02-01

    Coral bleaching events occur primarily due to increased seawater temperatures that results in the expulsion and/or reduction of endosymbiotic zooxanthellae. The Adaptive Bleaching Hypothesis suggests that bleaching events allow a different symbiont to populate the host. Specifically, the Symbiodinium clade D has been shown to increase in abundance following a bleaching event. Approximately 40 coral tissue samples (Orbicella annularis and Orbicella faveolata) were collected in the Florida Keys in March, May, August, and November of 2000, and analyzed using GC-MS for molecular biomarkers to determine if a different suite of compounds is produced at different times following the severe bleaching events in 1997 and 1998, and to relate the biomarker composition and levels to the symbiont(s) that were present in the corals. Our preliminary results show a predominant presence of saccharides (e.g., glucose, sucrose) and sterols (e.g., cholesterol, campesterol, brassicasterol), and to a lesser degree saturated (C16:0, C18:0, C20:0) and unsaturated fatty acids (C16:1; C18:1; C18:2; C20:4). The corals with the bleaching resistant clade D symbiont have higher levels of sterols as compared to corals with other non-resistant symbionts that were collected at the same time point. Concentrations of both sterols and saccharides increased throughout time, especially from March to May, which may indicate a recovery of the corals.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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...

  12. Global patterns and impacts of El Niño events on coral reefs: A meta-analysis

    OpenAIRE

    Claar, Danielle C.; Szostek, Lisa; McDevitt-Irwin, Jamie M.; Schanze, Julian J.; Baum, Julia K.

    2018-01-01

    Impacts of global climate change on coral reefs are being amplified by pulse heat stress events, including El Niño, the warm phase of the El Niño Southern Oscillation (ENSO). Despite reports of extensive coral bleaching and up to 97% coral mortality induced by El Niño events, a quantitative synthesis of the nature, intensity, and drivers of El Niño and La Niña impacts on corals is lacking. Herein, we first present a global meta-analysis of studies quantifying the effects of El Niño/La Niña-wa...

  13. Changes in bleaching susceptibility among corals subject to ocean warming and recurrent bleaching in Moorea, French Polynesia.

    Science.gov (United States)

    Pratchett, Morgan S; McCowan, Dominique; Maynard, Jeffrey A; Heron, Scott F

    2013-01-01

    Climate-induced coral bleaching poses a major threat to coral reef ecosystems, mostly because of the sensitivities of key habitat-forming corals to increasing temperature. However, susceptibility to bleaching varies greatly among coral genera and there are likely to be major changes in the relative abundance of different corals, even if the wholesale loss of corals does not occur for several decades. Here we document variation in bleaching susceptibility among key genera of reef-building corals in Moorea, French Polynesia, and compare bleaching incidence during mass-bleaching events documented in 1991, 1994, 2002 and 2007. This study compared the proportion of colonies that bleached for four major genera of reef-building corals (Acropora, Montipora, Pocillopora and Porites), during each of four well-documented bleaching events from 1991 to 2007. Acropora and Montipora consistently bleached in far greater proportions (up to 98%) than Pocillopora and Porites. However, there was an apparent and sustained decline in the proportion of colonies that bleached during successive bleaching events, especially for Acropora and Montipora. In 2007, only 77% of Acropora colonies bleached compared with 98% in 1991. Temporal variation in the proportion of coral colonies bleached may be attributable to differences in environmental conditions among years. Alternately, the sustained declines in bleaching incidence among highly susceptible corals may be indicative of acclimation or adaptation. Coral genera that are highly susceptible to coral bleaching, and especially Acropora and Montipora, exhibit temporal declines in their susceptibility to thermal anomalies at Moorea, French Polynesia. One possible explanation for these findings is that gradual removal of highly susceptible genotypes (through selective mortality of individuals, populations, and/or species) is producing a coral assemblage that is more resistant to sustained and ongoing ocean warming.

  14. Changes in Bleaching Susceptibility among Corals Subject to Ocean Warming and Recurrent Bleaching in Moorea, French Polynesia

    Science.gov (United States)

    Pratchett, Morgan S.; McCowan, Dominique; Maynard, Jeffrey A.; Heron, Scott F.

    2013-01-01

    Background Climate-induced coral bleaching poses a major threat to coral reef ecosystems, mostly because of the sensitivities of key habitat-forming corals to increasing temperature. However, susceptibility to bleaching varies greatly among coral genera and there are likely to be major changes in the relative abundance of different corals, even if the wholesale loss of corals does not occur for several decades. Here we document variation in bleaching susceptibility among key genera of reef-building corals in Moorea, French Polynesia, and compare bleaching incidence during mass-bleaching events documented in 1991, 1994, 2002 and 2007. Methodology/Principal Findings This study compared the proportion of colonies that bleached for four major genera of reef-building corals (Acropora, Montipora, Pocillopora and Porites), during each of four well-documented bleaching events from 1991 to 2007. Acropora and Montipora consistently bleached in far greater proportions (up to 98%) than Pocillopora and Porites. However, there was an apparent and sustained decline in the proportion of colonies that bleached during successive bleaching events, especially for Acropora and Montipora. In 2007, only 77% of Acropora colonies bleached compared with 98% in 1991. Temporal variation in the proportion of coral colonies bleached may be attributable to differences in environmental conditions among years. Alternately, the sustained declines in bleaching incidence among highly susceptible corals may be indicative of acclimation or adaptation. Conclusions/Significance Coral genera that are highly susceptible to coral bleaching, and especially Acropora and Montipora, exhibit temporal declines in their susceptibility to thermal anomalies at Moorea, French Polynesia. One possible explanation for these findings is that gradual removal of highly susceptible genotypes (through selective mortality of individuals, populations, and/or species) is producing a coral assemblage that is more resistant to

  15. Coral Bleaching Assessment Through Remote Sensing and Integrated Citizen Science (CoralBASICS): Engaging Dive Instructors on Reef Characterization in Southwest, Puerto Rico Coupled with the Analysis of Water Quality Using NASA Earth Observations

    Science.gov (United States)

    Torres-Perez, J. L.; Armstrong, R.; Detres, Y.; Aragones-Fred, C.; Melendez, J.

    2017-12-01

    As recurrences of extreme sea water thermal events increase with climate change, the need for continuous monitoring of coral reefs becomes even more evident. Enabling properly trained members from the local communities to actively participate in scientific programs/research projects, provides for such monitoring at little cost once the citizens are properly trained and committed. Further, the possibility of obtaining high temporal resolution data with citizen scientists can provide for new venues to answer questions that may not be answered with traditional research approaches. The CoralBASICS project engages members of the local diving industry in Puerto Rico on the assessment of coastal water quality and the status of Puerto Rico's coral reefs in an age of climate change and in particular, an increase in the frequency and magnitude of coral bleaching events. The project complements remote sensing data with community-based field assessments strictly supervised by the PI's. The study focuses on training citizen scientists (dive instructors) on the collection of benthic information related to the state of coral reefs using the Reef Check (fish and invertebrates ID and substrate composition) and video transects methodologies, monitoring of coral bleaching events, and collecting of water quality data using a smartphone ocean color application. The data collected by citizen scientists complements the validation of Landsat-8 (OLI) imagery for water quality assessment. At the same time, researchers from the University of Puerto Rico conduct field assessment of the bio-optical properties of waters surrounding the coral reef study areas. Dive instructors have been collecting benthic and water quality data for the past 4 months. Initial analysis using the Coral Point Count with excel extension (CPCe) software showed a dominance of gorgonians at most sites (up to 32.8%) with hard coral cover ranging between 5.5-13.2% of the hard substrates. No coral diseases or bleaching

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  18. A New Perspective: Assessing the Spatial Distribution of Coral Bleaching with Unmanned Low Altitude Remote Sensing Systems

    Science.gov (United States)

    Levy, J.; Franklin, E. C.; Hunter, C. L.

    2016-12-01

    Coral reefs are biodiversity hotspots that are vital to the function of global economic and biological processes. Coral bleaching is a significant contributor to the global decline of reefs and can impact an expansive reef area over short timescales. In order to understand the dynamics of coral bleaching and how these stress events impact reef ecosystems, it is important to conduct rapid bleaching surveys at functionally important spatial scales. Due to the inherent heterogeneity, size, and in some cases, remoteness of coral reefs, it is difficult to routinely monitor coral bleaching dynamics before, during, and after bleaching. Additionally, current in situ survey methods only collect snippets of discrete reef data over small reef areas, which are unable to accurately represent the reef as a whole. We present a new technique using small unmanned aerial systems (sUAS) as cost effective, efficient monitoring tools that target small to intermediate-scale reef dynamics to understand the spatial distribution of bleached coral colonies during the 2015 bleaching event on patch reefs in Kaneohe Bay, Oahu. Overlapping low altitude aerial images were collected at four reefs during the bleaching period and processed using Structure-from-Motion techniques to produce georeferenced and spatially accurate orthomosaics of complete reef areas. Mosaics were analyzed using manual and heuristic neural network classification schemes to identify comprehensive populations of bleached and live coral on each patch reef. We found that bleached colonies had random and clumped distributions on patch reefs in Kaneohe Bay depending on local environmental conditions. Our work demonstrates that sUAS provide a low cost, efficient platform that can rapidly and repeatedly collect high-resolution imagery (1 cm/pixel) and map large areas of shallow reef ecosystems (5 hectares). This study proves the feasibility of utilizing sUAS as a tool to collect spatially rich reef data that will provide reef

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

    Science.gov (United States)

    Sudek, M.; Work, Thierry 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.

  20. Predicting climate-driven regime shifts versus rebound potential in coral reefs.

    Science.gov (United States)

    Graham, Nicholas A J; Jennings, Simon; MacNeil, M Aaron; Mouillot, David; Wilson, Shaun K

    2015-02-05

    Climate-induced coral bleaching is among the greatest current threats to coral reefs, causing widespread loss of live coral cover. Conditions under which reefs bounce back from bleaching events or shift from coral 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 coral bleaching event that caused unprecedented region-wide mortality of Indo-Pacific corals. Following loss of >90% live coral cover, 12 of 21 reefs recovered towards pre-disturbance live coral states, while nine reefs underwent regime shifts to fleshy macroalgae. Functional diversity of associated reef fish communities shifted substantially following bleaching, 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 bleaching event. Recovery was favoured when reefs were structurally complex and in deeper water, when density of juvenile corals 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.

  1. Mass coral bleaching in the northern Persian Gulf, 2012

    Directory of Open Access Journals (Sweden)

    Javid Kavousi

    2014-09-01

    Full Text Available Coral bleaching events due to elevated temperatures are increasing in both frequency and magnitude worldwide. Mass bleaching was recorded at five sites in the northern Persian Gulf during August and September 2012. Based on available seawater temperature data from field, satellite and previous studies, we suggest that the coral bleaching threshold temperature in the northern Persian Gulf is between 33.5 and 34°C, which is about 1.5 to 2.5°C lower than that in the southern part. To assess the bleaching effects, coral genera counted during 60-minute dives were categorized into four groups including healthy, slightly bleached ( 50% bleached tissue and fully bleached colonies. The anomalously high sea surface temperature resulted in massive coral bleaching (~84% coral colonies affected. Acropora spp. colonies, which are known as the most vulnerable corals to thermal stress, were less affected by the bleaching than massive corals, such as Porites, which are among the most thermo-tolerant corals. Turbid waters, suggested as coral refugia against global warming, did not protect corals in this study since most affected corals were found in the most turbid waters. The 2012 bleaching in the northern Persian Gulf was relatively strong from the viewpoint of coral bleaching severity. Long-term monitoring is needed to understand the actual consequences of the bleaching event on the coral reefs and communities.

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

    Science.gov (United States)

    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. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. Coral bleaching pathways under the control of regional temperature variability

    Science.gov (United States)

    Langlais, C. E.; Lenton, A.; Heron, S. F.; Evenhuis, C.; Sen Gupta, A.; Brown, J. N.; Kuchinke, M.

    2017-11-01

    Increasing sea surface temperatures (SSTs) are predicted to adversely impact coral populations worldwide through increasing thermal bleaching events. Future bleaching is unlikely to be spatially uniform. Therefore, understanding what determines regional differences will be critical for adaptation management. Here, using a cumulative heat stress metric, we show that characteristics of regional SST determine the future bleaching risk patterns. Incorporating observed information on SST variability, in assessing future bleaching risk, provides novel options for management strategies. As a consequence, the known biases in climate model variability and the uncertainties in regional warming rate across climate models are less detrimental than previously thought. We also show that the thresholds used to indicate reef viability can strongly influence a decision on what constitutes a potential refugia. Observing and understanding the drivers of regional variability, and the viability limits of coral reefs, is therefore critical for making meaningful projections of coral bleaching risk.

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

    Science.gov (United States)

    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 ...

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

    Directory of Open Access Journals (Sweden)

    David A. Anderson

    2016-02-01

    Full Text Available 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.

  6. Local stressors reduce coral resilience to bleaching.

    Science.gov (United States)

    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. Assessing the spatial distribution of coral bleaching using small unmanned aerial systems

    Science.gov (United States)

    Levy, Joshua; Hunter, Cynthia; Lukacazyk, Trent; Franklin, Erik C.

    2018-06-01

    Small unmanned aerial systems (sUAS) are an affordable, effective complement to existing coral reef monitoring and assessment tools. sUAS provide repeatable low-altitude, high-resolution photogrammetry to address fundamental questions of spatial ecology and community dynamics for shallow coral reef ecosystems. Here, we qualitatively describe the use of sUAS to survey the spatial characteristics of coral cover and the distribution of coral bleaching across patch reefs in Kānéohe Bay, Hawaii, and address limitations and anticipated technology advancements within the field of UAS. Overlapping sub-decimeter low-altitude aerial reef imagery collected during the 2015 coral bleaching event was used to construct high-resolution reef image mosaics of coral bleaching responses on four Kānéohe Bay patch reefs, totaling 60,000 m2. Using sUAS imagery, we determined that paled, bleached and healthy corals on all four reefs were spatially clustered. Comparative analyses of data from sUAS imagery and in situ diver surveys found as much as 14% difference in coral cover values between survey methods, depending on the size of the reef and area surveyed. When comparing the abundance of unhealthy coral (paled and bleached) between sUAS and in situ diver surveys, we found differences in cover from 1 to 49%, depending on the depth of in situ surveys, the percent of reef area covered with sUAS surveys and patchiness of the bleaching response. This study demonstrates the effective use of sUAS surveys for assessing the spatial dynamics of coral bleaching at colony-scale resolutions across entire patch reefs and evaluates the complementarity of data from both sUAS and in situ diver surveys to more accurately characterize the spatial ecology of coral communities on reef flats and slopes.

  8. Environmental Drivers of Variation in Bleaching Severity of Acropora Species during an Extreme Thermal Anomaly

    Directory of Open Access Journals (Sweden)

    Mia O. Hoogenboom

    2017-11-01

    Full Text Available High sea surface temperatures caused global coral bleaching during 2015–2016. During this thermal stress event, we quantified within- and among-species variability in bleaching severity for critical habitat-forming Acropora corals. The objective of this study was to understand the drivers of spatial and species-specific variation in the bleaching susceptibility of these corals, and to evaluate whether bleaching susceptibility under extreme thermal stress was consistent with that observed during less severe bleaching events. We surveyed and mapped Acropora corals at 10 sites (N = 596 around the Lizard Island group on the northern Great Barrier Reef. For each colony, bleaching severity was quantified using a new image analysis technique, and we assessed whether small-scale environmental variables (depth, microhabitat, competition intensity and species traits (colony morphology, colony size, known symbiont clade association explained variation in bleaching. Results showed that during severe thermal stress, bleaching of branching corals was linked to microhabitat features, and was more severe at reef edge compared with lagoonal sites. Bleaching severity worsened over a very short time-frame (~1 week, but did not differ systematically with water depth, competition intensity, or colony size. At our study location, within- and among-species variation in bleaching severity was relatively low compared to the level of variation reported in the literature. More broadly, our results indicate that variability in bleaching susceptibility during extreme thermal stress is not consistent with that observed during previous bleaching events that have ranged in severity among globally dispersed sites, with fewer species escaping bleaching during severe thermal stress. In addition, shaded microhabitats can provide a refuge from bleaching which provides further evidence of the importance of topographic complexity for maintaining the biodiversity and ecosystem

  9. Dynamics of coral-associated microbiomes during a thermal bleaching event.

    Science.gov (United States)

    Pootakham, Wirulda; Mhuantong, Wuttichai; Putchim, Lalita; Yoocha, Thippawan; Sonthirod, Chutima; Kongkachana, Wasitthee; Sangsrakru, Duangjai; Naktang, Chaiwat; Jomchai, Nukoon; Thongtham, Nalinee; Tangphatsornruang, Sithichoke

    2018-03-23

    Coral-associated microorganisms play an important role in their host fitness and survival. A number of studies have demonstrated connections between thermal tolerance in corals and the type/relative abundance of Symbiodinium they harbor. More recently, the shifts in coral-associated bacterial profiles were also shown to be linked to the patterns of coral heat tolerance. Here, we investigated the dynamics of Porites lutea-associated bacterial and algal communities throughout a natural bleaching event, using full-length 16S rRNA and internal transcribed spacer sequences (ITS) obtained from PacBio circular consensus sequencing. We provided evidence of significant changes in the structure and diversity of coral-associated microbiomes during thermal stress. The balance of the symbiosis shifted from a predominant association between corals and Gammaproteobacteria to a predominance of Alphaproteobacteria and to a lesser extent Betaproteobacteria following the bleaching event. On the contrary, the composition and diversity of Symbiodinium communities remained unaltered throughout the bleaching event. It appears that the switching and/or shuffling of Symbiodinium types may not be the primary mechanism used by P. lutea to cope with increasing seawater temperature. The shifts in the structure and diversity of associated bacterial communities may contribute more to the survival of the coral holobiont under heat stress. © 2018 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  10. Temporal dynamics of black band disease affecting pillar coral ( Dendrogyra cylindrus) following two consecutive hyperthermal events on the Florida Reef Tract

    Science.gov (United States)

    Lewis, Cynthia L.; Neely, Karen L.; Richardson, Laurie L.; Rodriguez-Lanetty, Mauricio

    2017-06-01

    Black band disease (BBD) affects many coral species worldwide and is considered a major contributor to the decline of reef-building coral. On the Florida Reef Tract BBD is most prevalent during summer and early fall when water temperatures exceed 29 °C. BBD is rarely reported in pillar coral ( Dendrogyra cylindrus) throughout the Caribbean, and here we document for the first time the appearance of the disease in this species on Florida reefs. The highest monthly BBD prevalence in the D. cylindrus population were 4.7% in 2014 and 6.8% in 2015. In each year, BBD appeared immediately following a hyperthermal bleaching event, which raises concern as hyperthermal seawater anomalies become more frequent.

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

    Science.gov (United States)

    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.

  12. Temporary refugia for coral reefs in a warming world

    Science.gov (United States)

    van Hooidonk, R.; Maynard, J. A.; Planes, S.

    2013-05-01

    Climate-change impacts on coral reefs are expected to include temperature-induced spatially extensive bleaching events. Bleaching causes mortality when temperature stress persists but exposure to bleaching conditions is not expected to be spatially uniform at the regional or global scale. Here we show the first maps of global projections of bleaching 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 bleaching 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 bleaching conditions are similar for each of the RCPs. For RCP 8.5, 26% of reef cells are projected to experience annual bleaching 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 bleaching in ~ 23% of reef cells more than two decades, which might conceivably increase the potential for these reefs to cope with these changes.

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

    KAUST Repository

    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 host

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

    KAUST Repository

    Hobbs, Jean-Paul A.

    2013-08-08

    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 host

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

    Science.gov (United States)

    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. © 2014 John Wiley & Sons Ltd.

  16. Spatial and temporal patterns of mass bleaching of corals in the Anthropocene

    Science.gov (United States)

    Hughes, Terry P.; Anderson, Kristen D.; Connolly, Sean R.; Heron, Scott F.; Kerry, James T.; Lough, Janice M.; Baird, Andrew H.; Baum, Julia K.; Berumen, Michael L.; Bridge, Tom C.; Claar, Danielle C.; Eakin, C. Mark; Gilmour, James P.; Graham, Nicholas A. J.; Harrison, Hugo; Hobbs, Jean-Paul A.; Hoey, Andrew S.; Hoogenboom, Mia; Lowe, Ryan J.; McCulloch, Malcolm T.; Pandolfi, John M.; Pratchett, Morgan; Schoepf, Verena; Torda, Gergely; Wilson, Shaun K.

    2018-01-01

    Tropical reef systems are transitioning to a new era in which the interval between recurrent bouts of coral bleaching is too short for a full recovery of mature assemblages. We analyzed bleaching records at 100 globally distributed reef locations from 1980 to 2016. The median return time between pairs of severe bleaching events has diminished steadily since 1980 and is now only 6 years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Niña conditions than they were during El Niño events three decades ago. Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Niño–Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades.

  17. Spatial and temporal patterns of mass bleaching of corals in the Anthropocene

    KAUST Repository

    Hughes, Terry P.

    2018-01-16

    Tropical reef systems are transitioning to a new era in which the interval between recurrent bouts of coral bleaching is too short for a full recovery of mature assemblages. We analyzed bleaching records at 100 globally distributed reef locations from 1980 to 2016. The median return time between pairs of severe bleaching events has diminished steadily since 1980 and is now only 6 years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Nina conditions than they were during El Nino events three decades ago. Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Nino-Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades.

  18. Spatial and temporal patterns of mass bleaching of corals in the Anthropocene

    KAUST Repository

    Hughes, Terry P.; Anderson, Kristen D.; Connolly, Sean R.; Heron, Scott F.; Kerry, James T.; Lough, Janice M.; Baird, Andrew H.; Baum, Julia K.; Berumen, Michael L.; Bridge, Tom C.; Claar, Danielle C.; Eakin, C. Mark; Gilmour, James P.; Graham, Nicholas A. J.; Harrison, Hugo; Hobbs, Jean-Paul A.; Hoey, Andrew S.; Hoogenboom, Mia; Lowe, Ryan J.; McCulloch, Malcolm T.; Pandolfi, John M.; Pratchett, Morgan; Schoepf, Verena; Torda, Gergely; Wilson, Shaun K.

    2018-01-01

    Tropical reef systems are transitioning to a new era in which the interval between recurrent bouts of coral bleaching is too short for a full recovery of mature assemblages. We analyzed bleaching records at 100 globally distributed reef locations from 1980 to 2016. The median return time between pairs of severe bleaching events has diminished steadily since 1980 and is now only 6 years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Nina conditions than they were during El Nino events three decades ago. Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Nino-Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Loke Ming Chou

    Full Text Available 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. Symbiotic immuno-suppression: is disease susceptibility the price of bleaching resistance?

    Science.gov (United States)

    Merselis, Daniel G; Lirman, Diego; Rodriguez-Lanetty, Mauricio

    2018-01-01

    Accelerating anthropogenic climate change threatens to destroy coral reefs worldwide through the processes of bleaching and disease. These major contributors to coral mortality are both closely linked with thermal stress intensified by anthropogenic climate change. Disease outbreaks typically follow bleaching events, but a direct positive linkage between bleaching and disease has been debated. By tracking 152 individual coral ramets through the 2014 mass bleaching in a South Florida coral restoration nursery, we revealed a highly significant negative correlation between bleaching and disease in the Caribbean staghorn coral, Acropora cervicornis . To explain these results, we propose a mechanism for transient immunological protection through coral bleaching: removal of Symbiodinium during bleaching may also temporarily eliminate suppressive symbiont modulation of host immunological function. We contextualize this hypothesis within an ecological perspective in order to generate testable predictions for future investigation.

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

    Science.gov (United States)

    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. © 2014 John Wiley & Sons Ltd.

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

    Energy Technology Data Exchange (ETDEWEB)

    Donner, S.D. [Princeton Univ., NJ (United States). Woodrow Wilson School of Public and International Affairs; Knutson, T.R. [National Oceanic and Atmospheric Administration, Princeton, NJ (United States). Geophysical Fluid Dynamics Lab.; Oppenheimer, M. [Princeton Univ., NJ (United States). Dept. of Geosciences

    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.

  6. Viral outbreak in corals associated with an in situ bleaching event: atypical herpes-like viruses and a new megavirus infecting Symbiodinium

    Directory of Open Access Journals (Sweden)

    Adrienne M.S. Correa

    2016-02-01

    Full Text Available 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 nm, ~120 nm, 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 viral 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

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

    Science.gov (United States)

    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

  8. Coral Ecosystem Resilience, Conservation and Management on the Reefs of Jamaica in the Face of Anthropogenic Activities and Climate Change

    Directory of Open Access Journals (Sweden)

    M. James C. Crabbe

    2010-06-01

    Full Text Available Knowledge of factors that are important in reef resilience and integrity help us understand how reef ecosystems react following major anthropogenic and environmental disturbances. The North Jamaican fringing reefs have shown some recent resilience to acute disturbances from hurricanes and bleaching, in addition to the recurring chronic stressors of over-fishing and land development. Factors that can improve coral reef resilience are reviewed, and reef rugosity is shown to correlate with coral cover and growth, particularly for branching Acropora species. The biodiversity index for the Jamaican reefs was lowered after the 2005 mass bleaching event, as were the numbers of coral colonies, but both had recovered by 2009. The importance of coastal zone reef management strategies and the economic value of reefs are discussed, and a protocol is suggested for future management of Jamaican reefs.

  9. Remote Sensing of Coral Bleaching Using Temperature and Light: Progress towards an Operational Algorithm

    Directory of Open Access Journals (Sweden)

    William Skirving

    2017-12-01

    Full Text Available The National Oceanic and Atmospheric Administration’s Coral Reef Watch program developed and operates several global satellite products to monitor bleaching-level heat stress. While these products have a proven ability to predict the onset of most mass coral bleaching events, they occasionally miss events; inaccurately predict the severity of some mass coral bleaching events; or report false alarms. These products are based solely on temperature and yet coral bleaching is known to result from both temperature and light stress. This study presents a novel methodology (still under development, which combines temperature and light into a single measure of stress to predict the onset and severity of mass coral bleaching. We describe here the biological basis of the Light Stress Damage (LSD algorithm under development. Then by using empirical relationships derived in separate experiments conducted in mesocosm facilities in the Mexican Caribbean we parameterize the LSD algorithm and demonstrate that it is able to describe three past bleaching events from the Great Barrier Reef (GBR. For this limited example, the LSD algorithm was able to better predict differences in the severity of the three past GBR bleaching events, quantifying the contribution of light to reduce or exacerbate the impact of heat stress. The new Light Stress Damage algorithm we present here is potentially a significant step forward in the evolution of satellite-based bleaching products.

  10. Warm-water coral reefs and climate change.

    Science.gov (United States)

    Spalding, Mark D; Brown, Barbara E

    2015-11-13

    Coral 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 bleaching events that can lead to the loss of both coral 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 coral reefs is increasingly bleak. Copyright © 2015, American Association for the Advancement of Science.

  11. Repeated Thermal Stress, Shading, and Directional Selection in the Florida Reef Tract

    OpenAIRE

    Robert van Woesik; Kelly R. McCaffrey

    2017-01-01

    Over the last three decades reef corals have been subjected to an unprecedented frequency and intensity of thermal-stress events, which have led to extensive coral bleaching, disease, and mortality. Over the next century, the climate is predicted to drive sea-surface temperatures to even higher levels, consequently increasing the risk of mass bleaching and disease outbreaks. Yet, there is considerable temporal and spatial variation in coral bleaching and in disease prevalence. Using data coll...

  12. Prey selection of corallivorous muricids at Koh Tao (Gulf of Thailand) four years after a major coral bleaching event

    NARCIS (Netherlands)

    Moerland, M.S.; Scott, C.M.; Hoeksema, B.W.

    2016-01-01

    Corallivorous Drupella (Muricidae) snails at Koh Tao are reported to have extended their range of prey species following a major coral bleaching event in 2010. Populations of their preferred Acropora prey had locally diminished in both size and abundance, and the snails had introduced free-living

  13. Thermal refugia against coral bleaching throughout the northern Red Sea

    KAUST Repository

    Osman, Eslam O.

    2017-10-17

    Tropical reefs have been impacted by thermal anomalies caused by global warming that induced coral bleaching and mortality events globally. However, there have only been very few recordings of bleaching within the Red Sea despite covering a latitudinal range of 15° and consequently it has been considered a region that is less sensitive to thermal anomalies. We therefore examined historical patterns of sea surface temperature (SST) and associated anomalies (1982–2012) and compared warming trends with a unique compilation of corresponding coral bleaching records from throughout the region. These data indicated that the northern Red Sea has not experienced mass bleaching despite intensive Degree Heating Weeks (DHW) of >15°C-weeks. Severe bleaching was restricted to the central and southern Red Sea where DHWs have been more frequent, but far less intense (DHWs <4°C-weeks). A similar pattern was observed during the 2015–2016 El Niño event during which time corals in the northern Red Sea did not bleach despite high thermal stress (i.e. DHWs >8°C-weeks), and bleaching was restricted to the central and southern Red Sea despite the lower thermal stress (DHWs < 8°C-weeks). Heat stress assays carried out in the northern (Hurghada) and central (Thuwal) Red Sea on four key reef-building species confirmed different regional thermal susceptibility, and that central Red Sea corals are more sensitive to thermal anomalies as compared to those from the north. Together, our data demonstrate that corals in the northern Red Sea have a much higher heat tolerance than their prevailing temperature regime would suggest. In contrast, corals from the central Red Sea are close to their thermal limits, which closely match the maximum annual water temperatures. The northern Red Sea harbours reef-building corals that live well below their bleaching thresholds and thus we propose that the region represents a thermal refuge of global importance.

  14. Thermal refugia against coral bleaching throughout the northern Red Sea

    KAUST Repository

    Osman, Eslam O.; Smith, David J.; Ziegler, Maren; Kü rten, Benjamin; Conrad, Constanze; El-Haddad, Khaled M.; Voolstra, Christian R.; Suggett, David J.

    2017-01-01

    Tropical reefs have been impacted by thermal anomalies caused by global warming that induced coral bleaching and mortality events globally. However, there have only been very few recordings of bleaching within the Red Sea despite covering a latitudinal range of 15° and consequently it has been considered a region that is less sensitive to thermal anomalies. We therefore examined historical patterns of sea surface temperature (SST) and associated anomalies (1982–2012) and compared warming trends with a unique compilation of corresponding coral bleaching records from throughout the region. These data indicated that the northern Red Sea has not experienced mass bleaching despite intensive Degree Heating Weeks (DHW) of >15°C-weeks. Severe bleaching was restricted to the central and southern Red Sea where DHWs have been more frequent, but far less intense (DHWs <4°C-weeks). A similar pattern was observed during the 2015–2016 El Niño event during which time corals in the northern Red Sea did not bleach despite high thermal stress (i.e. DHWs >8°C-weeks), and bleaching was restricted to the central and southern Red Sea despite the lower thermal stress (DHWs < 8°C-weeks). Heat stress assays carried out in the northern (Hurghada) and central (Thuwal) Red Sea on four key reef-building species confirmed different regional thermal susceptibility, and that central Red Sea corals are more sensitive to thermal anomalies as compared to those from the north. Together, our data demonstrate that corals in the northern Red Sea have a much higher heat tolerance than their prevailing temperature regime would suggest. In contrast, corals from the central Red Sea are close to their thermal limits, which closely match the maximum annual water temperatures. The northern Red Sea harbours reef-building corals that live well below their bleaching thresholds and thus we propose that the region represents a thermal refuge of global importance.

  15. Caribbean corals in crisis: record thermal stress, bleaching, and mortality in 2005.

    Science.gov (United States)

    Eakin, C Mark; Morgan, Jessica A; Heron, Scott F; Smith, Tyler B; Liu, Gang; Alvarez-Filip, Lorenzo; Baca, Bart; Bartels, Erich; Bastidas, Carolina; Bouchon, Claude; Brandt, Marilyn; Bruckner, Andrew W; Bunkley-Williams, Lucy; Cameron, Andrew; Causey, Billy D; Chiappone, Mark; Christensen, Tyler R L; Crabbe, M James C; Day, Owen; de la Guardia, Elena; Díaz-Pulido, Guillermo; DiResta, Daniel; Gil-Agudelo, Diego L; Gilliam, David S; Ginsburg, Robert N; Gore, Shannon; Guzmán, Héctor M; Hendee, James C; Hernández-Delgado, Edwin A; Husain, Ellen; Jeffrey, Christopher F G; Jones, Ross J; Jordán-Dahlgren, Eric; Kaufman, Les S; Kline, David I; Kramer, Philip A; Lang, Judith C; Lirman, Diego; Mallela, Jennie; Manfrino, Carrie; Maréchal, Jean-Philippe; Marks, Ken; Mihaly, Jennifer; Miller, W Jeff; Mueller, Erich M; Muller, Erinn M; Orozco Toro, Carlos A; Oxenford, Hazel A; Ponce-Taylor, Daniel; Quinn, Norman; Ritchie, Kim B; Rodríguez, Sebastián; Ramírez, Alberto Rodríguez; Romano, Sandra; Samhouri, Jameal F; Sánchez, Juan A; Schmahl, George P; Shank, Burton V; Skirving, William J; Steiner, Sascha C C; Villamizar, Estrella; Walsh, Sheila M; Walter, Cory; Weil, Ernesto; Williams, Ernest H; Roberson, Kimberly Woody; Yusuf, Yusri

    2010-11-15

    The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.

  16. Caribbean corals in crisis: record thermal stress, bleaching, and mortality in 2005.

    Directory of Open Access Journals (Sweden)

    C Mark Eakin

    Full Text Available BACKGROUND: The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. METHODOLOGY/PRINCIPAL FINDINGS: Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. CONCLUSIONS/SIGNIFICANCE: Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.

  17. Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005

    Science.gov (United States)

    Eakin, C. Mark; Morgan, Jessica A.; Heron, Scott F.; Smith, Tyler B.; Liu, Gang; Alvarez-Filip, Lorenzo; Baca, Bart; Bartels, Erich; Bastidas, Carolina; Bouchon, Claude; Brandt, Marilyn; Bruckner, Andrew W.; Bunkley-Williams, Lucy; Cameron, Andrew; Causey, Billy D.; Chiappone, Mark; Christensen, Tyler R. L.; Crabbe, M. James C; Day, Owen; de la Guardia, Elena; Díaz-Pulido, Guillermo; DiResta, Daniel; Gil-Agudelo, Diego L.; Gilliam, David S.; Ginsburg, Robert N.; Gore, Shannon; Guzmán, Héctor M.; Hendee, James C.; Hernández-Delgado, Edwin A.; Husain, Ellen; Jeffrey, Christopher F. G.; Jones, Ross J.; Jordán-Dahlgren, Eric; Kaufman, Les S.; Kline, David I.; Kramer, Philip A.; Lang, Judith C.; Lirman, Diego; Mallela, Jennie; Manfrino, Carrie; Maréchal, Jean-Philippe; Marks, Ken; Mihaly, Jennifer; Miller, W. Jeff; Mueller, Erich M.; Muller, Erinn M.; Orozco Toro, Carlos A.; Oxenford, Hazel A.; Ponce-Taylor, Daniel; Quinn, Norman; Ritchie, Kim B.; Rodríguez, Sebastián; Ramírez, Alberto Rodríguez; Romano, Sandra; Samhouri, Jameal F.; Sánchez, Juan A.; Schmahl, George P.; Shank, Burton V.; Skirving, William J.; Steiner, Sascha C. C.; Villamizar, Estrella; Walsh, Sheila M.; Walter, Cory; Weil, Ernesto; Williams, Ernest H.; Roberson, Kimberly Woody; Yusuf, Yusri

    2010-01-01

    Background The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. Methodology/Principal Findings Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. Conclusions/Significance Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate. PMID:21125021

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

    Science.gov (United States)

    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

  19. Thermal stress exposure, bleaching response, and mortality in the threatened coral Acropora palmata.

    Science.gov (United States)

    Williams, D E; Miller, M W; Bright, A J; Pausch, R E; Valdivia, A

    2017-11-15

    Demographic data for Elkhorn coral, Acropora palmata, and in situ water temperature data from seven upper Florida Keys (USA) reefs revealed three warm thermal stress events between 2010 and 2016. During a mild bleaching event in 2011, up to 59% of colonies bleached, but no mortality resulted. In both 2014 and 2015, severe and unprecedented bleaching was observed with up to 100% of colonies bleached. A. palmata live tissue cover declined by one-third following the 2014-2015 events. Colony mortality of mildly- and non-bleached colonies did not differ but increased significantly with more severe bleaching. Increased bleaching prevalence corresponded to maximum daily average water temperatures above 31.3°C. However, the cumulative days with daily average exceeding 31.0°C provided a better predictor of bleaching response. The bleaching response of surviving colonies in 2015 was not consistent with acclimatization as most individual colonies bleached at least as badly as in 2014. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Coral reefs as drivers of cladogenesis: expanding coral reefs, cryptic extinction events, and the development of biodiversity hotspots.

    Science.gov (United States)

    Cowman, P F; Bellwood, D R

    2011-12-01

    Diversification rates within four conspicuous coral reef fish families (Labridae, Chaetodontidae, Pomacentridae and Apogonidae) were estimated using Bayesian inference. Lineage through time plots revealed a possible late Eocene/early Oligocene cryptic extinction event coinciding with the collapse of the ancestral Tethyan/Arabian hotspot. Rates of diversification analysis revealed elevated cladogenesis in all families in the Oligocene/Miocene. Throughout the Miocene, lineages with a high percentage of coral reef-associated taxa display significantly higher net diversification rates than expected. The development of a complex mosaic of reef habitats in the Indo-Australian Archipelago (IAA) during the Oligocene/Miocene appears to have been a significant driver of cladogenesis. Patterns of diversification suggest that coral reefs acted as a refuge from high extinction, as reef taxa are able to sustain diversification at high extinction rates. The IAA appears to support both cladogenesis and survival in associated lineages, laying the foundation for the recent IAA marine biodiversity hotspot. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.

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

    Science.gov (United States)

    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.

  2. Dampak Pemutihan Karang Tahun 2016 Terhadap Ekosistem Terumbu Karang: Studi Kasus Di TWP Gili Matra (Gili Air, Gili Meno dan Gili Trawangan Provinsi NTB Coral Bleaching Impact in 2016 Towards Coral Reef Ecosystem: Case Studies TWP Gili Matra (Gili Air,

    Directory of Open Access Journals (Sweden)

    Fakhrizal Setiawan

    2018-02-01

    Full Text Available ABSTRACTIncreased sea surface temperatures due to global warming that occurred from the early to mid 2016 caused of coral bleaching in several locations in TWP Gili Matra. Observations of coral bleaching  obtained from coral colonies compotition affected by bleaching (50%, white (18%, death (1% and was not affected (31%. These implications resulting decline in coral cover but not significant (F (1,013 = 0.333, p > 0.05 from 23,43% ± 2,61 SE in 2012 to 18,48% ± 4,14 SE in 2016 and a significant decrease (P (58,06 = 3,8e-06 recruitment of coral (coral Juvenil from 6,66 ind.m-1 ± 1,04 SE in 2012 to 1,41 ind.m-1 ± 0,16 SE in 2016. the other impact is a significant reduction (P(20.84 = 0,00053, p <0,001 the abundance of reef fish from 28.733,26 ind.ha-1 ± 3.757,89 SE in 2012 to 11.431,18 ind.ha-1 ± 702,53 SE in 2016 and a decline in the biomass of reef fish but not significant (F (0,58 = 0,46, P> 0.05 from 506,56 kg.ha-1 ± 99,05 SE in 2012 to 438,41 kg.ha-1 ± 45,69 SE in 2016. The decline of coral recruitment resulted in the recovery of the affected areas bleaching becomes slow because of the juvenile new coral mostly dead. The second impact of bleaching is an abundance of fish decrease, indicating that is available only fish big size (adult and very less of small fishes, including juvenile. Keywords: global warming, coral bleaching, coral cover, reef fishes

  3. 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

    Science.gov (United States)

    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.

  4. Patterns of bleaching and mortality following widespread warming events in 2014 and 2015 at the Hanauma Bay Nature Preserve, Hawai‘i

    Directory of Open Access Journals (Sweden)

    Ku‘ulei S. Rodgers

    2017-05-01

    Full Text Available Drastic increases in global carbon emissions in the past century have led to elevated sea surface temperatures that negatively affect coral reef organisms. Worldwide coral bleaching-related mortality is increasing and data has shown even isolated and protected reefs are vulnerable to the effects of global climate change. In 2014 and 2015, coral reefs in the main Hawaiian Islands (MHI suffered up to 90% bleaching, with higher than 50% subsequent mortality in some areas. The location and severity of bleaching and mortality was strongly influenced by the spatial and temporal patterns of elevated seawater temperatures. The main objective of this research was to understand the spatial extent of bleaching mortality in Hanauma Bay Nature Preserve (HBNP, O‘ahu, Hawai‘i to gain a baseline understanding of the physical processes that influence localized bleaching dynamics. Surveys at HBNP in October 2015 and January 2016 revealed extensive bleaching (47% and high levels of coral mortality (9.8%. Bleaching was highly variable among the four HBNP sectors and ranged from a low of ∼31% in the central bay at Channel (CH to a high of 57% in the area most frequented by visitors (Keyhole; KH. The highest levels of bleaching occurred in two sectors with different circulation patterns: KH experienced comparatively low circulation velocity and a low temperature increase while Witches Brew (WB and Backdoors (BD experienced higher circulation velocity and higher temperature increase. Cumulative mortality was highest at WB (5.0% and at BD (2.9% although WB circulation velocity is significantly higher. HBNP is minimally impacted by local factors that can lead to decline such as high fishing pressure or sedimentation although human use is high. Despite the lack of these influences, high coral mortality occurred. Visitor impacts are strikingly different in the two sectors that experienced the highest mortality evidenced by the differences in coral cover associated

  5. Patterns of bleaching and mortality following widespread warming events in 2014 and 2015 at the Hanauma Bay Nature Preserve, Hawai'i.

    Science.gov (United States)

    Rodgers, Ku'ulei S; Bahr, Keisha D; Jokiel, Paul L; Richards Donà, Angela

    2017-01-01

    Drastic increases in global carbon emissions in the past century have led to elevated sea surface temperatures that negatively affect coral reef organisms. Worldwide coral bleaching-related mortality is increasing and data has shown even isolated and protected reefs are vulnerable to the effects of global climate change. In 2014 and 2015, coral reefs in the main Hawaiian Islands (MHI) suffered up to 90% bleaching, with higher than 50% subsequent mortality in some areas. The location and severity of bleaching and mortality was strongly influenced by the spatial and temporal patterns of elevated seawater temperatures. The main objective of this research was to understand the spatial extent of bleaching mortality in Hanauma Bay Nature Preserve (HBNP), O'ahu, Hawai'i to gain a baseline understanding of the physical processes that influence localized bleaching dynamics. Surveys at HBNP in October 2015 and January 2016 revealed extensive bleaching (47%) and high levels of coral mortality (9.8%). Bleaching was highly variable among the four HBNP sectors and ranged from a low of ∼31% in the central bay at Channel (CH) to a high of 57% in the area most frequented by visitors (Keyhole; KH). The highest levels of bleaching occurred in two sectors with different circulation patterns: KH experienced comparatively low circulation velocity and a low temperature increase while Witches Brew (WB) and Backdoors (BD) experienced higher circulation velocity and higher temperature increase. Cumulative mortality was highest at WB (5.0%) and at BD (2.9%) although WB circulation velocity is significantly higher. HBNP is minimally impacted by local factors that can lead to decline such as high fishing pressure or sedimentation although human use is high. Despite the lack of these influences, high coral mortality occurred. Visitor impacts are strikingly different in the two sectors that experienced the highest mortality evidenced by the differences in coral cover associated with visitor

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    2013-05-02

    Franzisket L (1978) Coral growth: buoyant weight technique. In: Stoddart DR, Johannes RE, editors. Coral Reefs : Research Methods. Paris, France...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

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

    Science.gov (United States)

    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. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

  9. Application of the coral health chart to determine bleaching status of Acropora downingi in a subtropical coral reef

    Science.gov (United States)

    Oladi, Mahshid; Shokri, Mohammad Reza; Rajabi-Maham, Hassan

    2017-06-01

    The `Coral Health Chart' has become a popular tool for monitoring coral bleaching worldwide. The scleractinian coral Acropora downingi (Wallace 1999) is highly vulnerable to temperature anomalies in the Persian Gulf. Our study tested the reliability of Coral Health Chart scores for the assessment of bleaching-related changes in the mitotic index (MI) and density of zooxanthellae cells in A. downingi in Qeshm Island, the Persian Gulf. The results revealed that, at least under severe conditions, it can be used as an effective proxy for detecting changes in the density of normal, transparent, or degraded zooxanthellae and MI. However, its ability to discern changes in pigment concentration and total zooxanthellae density should be viewed with some caution in the Gulf region, probably because the high levels of environmental variability in this region result in inherent variations in the characteristics of zooxanthellae among "healthy" looking corals.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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 (bleaching. This indicates the existence of local resilience patterns against coral bleaching in Caribbean reefs. PMID:24282551

  13. Disease and stress-induced mortality of corals in Indian reefs and observations on bleaching of corals in the Andamans

    Digital Repository Service at National Institute of Oceanography (India)

    Ravindran, J.; Raghukumar, C.; Raghukumar, S.

    A study was carried out in the Lakshadweep and Andaman islands and the Gulf of Kutch to assess the health of corals in Indian reefs. Disease, predation and stress were the major factors of coral mortality. Death caused by diseases - the black band...

  14. Tsunami survey expedition: preliminary investigation of Maldivian coral reefs two weeks after the event.

    Science.gov (United States)

    Goffredo, Stefano; Piccinetti, Corrado; Zaccanti, Francesco

    2007-08-01

    On December 26th 2004, a earthquake west of Sumatra generated a devastating tsunami. Hundreds of thousands of people fell victim. Economic losses were greatest in those countries dependant on tourism. The impact in the Maldives on persons and things was modest. Immediately following the event and notwithstanding the lack of scientific data, the mass media gave catastrophic reports on the state of coral reefs in the area. This paper reports on the first survey on coral reefs in the Maldives after the Tsunami. Ocean walls, passes, inner reefs, and shoals in the North and South Malé atolls, were surveyed two weeks after the event. Significant damage was recorded in the passes in the South Malé atoll. Our observations showed that the damage was more or less extensive depending on latitude and topography. Sri Lanka may have broken the wave's rush, reducing the extent of the impact on northern atolls. The water's acceleration inside the passes was so intense as to cause reef collapses. The observed damage represents a minimum fraction of the entire coral reef system. Tourist perception of the area seems unchanged. These data may be used to disseminate correct information about the state of Maldives coral reefs, which would be useful in relaunching local economy.

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

    Science.gov (United States)

    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. © 2015 The Author(s).

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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.

  19. Mass coral bleaching due to unprecedented marine heatwave in Papahānaumokuākea Marine National Monument (Northwestern Hawaiian Islands).

    Science.gov (United States)

    Couch, Courtney S; Burns, John H R; Liu, Gang; Steward, Kanoelani; Gutlay, Tiffany Nicole; Kenyon, Jean; Eakin, C Mark; Kosaki, Randall K

    2017-01-01

    2014 marked the sixth and most widespread mass bleaching event reported in the Northwestern Hawaiian Islands, home to the Papahānaumokuākea Marine National Monument (PMNM), the world's second largest marine reserve. This event was associated with an unusual basin-scale warming in the North Pacific Ocean, with an unprecedented peak intensity of around 20°C-weeks of cumulative heat stress at Lisianksi Island. In situ bleaching surveys and satellite data were used to evaluate the relative importance of potential drivers of bleaching patterns in 2014, assess the subsequent morality and its effects on coral communities and 3D complexity, test for signs of regional acclimation, and investigate long-term change in heat stress in PMNM. Surveys conducted at four island/atoll (French Frigate Shoals, Lisianski Island, Pearl and Hermes Atoll, and Midway Atoll) showed that in 2014, percent bleaching varied considerably between islands/atolls and habitats (back reef/fore reef and depth), and was up to 91% in shallow habitats at Lisianski. The percent bleaching during the 2014 event was best explained by a combination of duration of heat stress measured by Coral Reef Watch's satellite Degree Heating Week, relative community susceptibility (bleaching susceptibility score of each taxon * the taxon's abundance relative to the total number of colonies), depth and region. Mean coral cover at permanent Lisianski monitoring sites decreased by 68% due to severe losses of Montipora dilatata complex, resulting in rapid reductions in habitat complexity. Spatial distribution of the 2014 bleaching was significantly different from the 2002 and 2004 bleaching events likely due to a combination of differences in heat stress and local acclimatization. Historical satellite data demonstrated heat stress in 2014 was unlike any previous event and that the exposure of corals to the bleaching-level heat stress has increased significantly in the northern PMNM since 1982, highlighting the increasing

  20. Mass coral bleaching due to unprecedented marine heatwave in Papahānaumokuākea Marine National Monument (Northwestern Hawaiian Islands.

    Directory of Open Access Journals (Sweden)

    Courtney S Couch

    Full Text Available 2014 marked the sixth and most widespread mass bleaching event reported in the Northwestern Hawaiian Islands, home to the Papahānaumokuākea Marine National Monument (PMNM, the world's second largest marine reserve. This event was associated with an unusual basin-scale warming in the North Pacific Ocean, with an unprecedented peak intensity of around 20°C-weeks of cumulative heat stress at Lisianksi Island. In situ bleaching surveys and satellite data were used to evaluate the relative importance of potential drivers of bleaching patterns in 2014, assess the subsequent morality and its effects on coral communities and 3D complexity, test for signs of regional acclimation, and investigate long-term change in heat stress in PMNM. Surveys conducted at four island/atoll (French Frigate Shoals, Lisianski Island, Pearl and Hermes Atoll, and Midway Atoll showed that in 2014, percent bleaching varied considerably between islands/atolls and habitats (back reef/fore reef and depth, and was up to 91% in shallow habitats at Lisianski. The percent bleaching during the 2014 event was best explained by a combination of duration of heat stress measured by Coral Reef Watch's satellite Degree Heating Week, relative community susceptibility (bleaching susceptibility score of each taxon * the taxon's abundance relative to the total number of colonies, depth and region. Mean coral cover at permanent Lisianski monitoring sites decreased by 68% due to severe losses of Montipora dilatata complex, resulting in rapid reductions in habitat complexity. Spatial distribution of the 2014 bleaching was significantly different from the 2002 and 2004 bleaching events likely due to a combination of differences in heat stress and local acclimatization. Historical satellite data demonstrated heat stress in 2014 was unlike any previous event and that the exposure of corals to the bleaching-level heat stress has increased significantly in the northern PMNM since 1982, highlighting

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Coles, S L; Brown, Barbara E

    2003-01-01

    conditions that have induced coral bleaching. Clearly, there are limits to acclimatory processes that can counter coral bleaching resulting from elevated sea temperatures, but scientific models will not accurately predict the fate of reef corals until we have a better understanding of coral-algal acclimatization/adaptation potential. Research is particularly needed with respect to the molecular and physiological mechanisms that promote thermal tolerance in corals and zooxanthellae and identification of genetic characteristics responsible for the variety of responses that occur in a coral bleaching event. Only then will we have some idea of the nature of likely responses, the timescales involved and the role of 'experience' in modifying bleaching impact.

  3. Island-enhanced cooling mechanism in typhoon events revealed by field observations and numerical simulations for a coral reef area, Sekisei Lagoon, Japan

    Science.gov (United States)

    Bernardo, Lawrence Patrick C.; Nadaoka, Kazuo; Nakamura, Takashi; Watanabe, Atsushi

    2017-11-01

    While widely known for their destructive power, typhoon events can also bring benefit to coral reef ecosystems through typhoon-induced cooling which can mitigate against thermally stressful conditions causing coral bleaching. Sensor deployments in Sekisei Lagoon, Japan's largest coral reef area, during the summer months of 2013, 2014, and 2015 were able to capture local hydrodynamic features of numerous typhoon passages. In particular, typhoons 2015-13 and 2015-15 featured steep drops in near-bottom temperature of 5 °C or more in the north and south sides of Sekisei Lagoon, respectively, indicating local cooling patterns which appeared to depend on the track and intensity of the passing typhoon. This was further investigated using Regional Ocean Modeling System (ROMS) numerical simulations conducted for the summer of 2015. The modeling results showed a cooling trend to the north of the Yaeyama Islands during the passage of typhoon 2015-13, and a cooling trend that moved clockwise from north to south of the islands during the passage of typhoon 2015-15. These local cooling events may have been initiated by the Yaeyama Islands acting as an obstacle to a strong typhoon-generated flow which was modulated and led to prominent cooling of waters on the leeward sides. These lower temperature waters from offshore may then be transported to the shallower inner parts of the lagoon area, which may partly be due to density-driven currents generated by the offshore-inner area temperature difference.

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

    Science.gov (United States)

    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

  5. Two spatial scales in a bleaching event: Corals from the mildest and the most extreme thermal environments escape mortality

    KAUST Repository

    Pineda, Jesú s; Starczak, Victoria; Tarrant, Ann; Blythe, Jonathan; Davis, Kristen; Farrar, Tom; Berumen, Michael L.; da Silva, José C. B.

    2013-01-01

    or increased modestly (0.5°C) in the outer and mid reefs relative to 2009. In the inner reef, 2010 temperatures were 1.4°C above the 2009 seasonal maximum for several weeks. We detected little or no coral mortality in mid and outer reefs. In the inner reef

  6. Water column productivity and temperature predict coral reef regeneration across the Indo-Pacific

    Science.gov (United States)

    Riegl, B.; Glynn, P. W.; Wieters, E.; Purkis, S.; D'Angelo, C.; Wiedenmann, J.

    2015-02-01

    Predicted increases in seawater temperatures accelerate coral reef decline due to mortality by heat-driven coral bleaching. Alteration of the natural nutrient environment of reef corals reduces tolerance of corals to heat and light stress and thus will exacerbate impacts of global warming on reefs. Still, many reefs demonstrate remarkable regeneration from past stress events. This paper investigates the effects of sea surface temperature (SST) and water column productivity on recovery of coral reefs. In 71 Indo-Pacific sites, coral cover changes over the past 1-3 decades correlated negative-exponentially with mean SST, chlorophyll a, and SST rise. At six monitoring sites (Persian/Arabian Gulf, Red Sea, northern and southern Galápagos, Easter Island, Panama), over half of all corals were coral reefs presently have the best chances for survival. However, reefs best buffered against temperature and nutrient effects are those that current studies suggest to be most at peril from future ocean acidification.

  7. Sugar enrichment provides evidence for a role of nitrogen fixation in coral bleaching

    KAUST Repository

    Pogoreutz, Claudia; Radecker, Nils; Cardenas, Anny; Gä rdes, Astrid; Voolstra, Christian R.; Wild, Christian

    2017-01-01

    The disruption of the coral-algae symbiosis (coral bleaching) due to rising sea surface temperatures has become an unprecedented global threat to coral reefs. Despite decades of research, our ability to manage mass bleaching events remains hampered by an incomplete mechanistic understanding of the processes involved. In this study, we induced a coral bleaching phenotype in the absence of heat and light stress by adding sugars. The sugar addition resulted in coral symbiotic breakdown accompanied by a fourfold increase of coral-associated microbial nitrogen fixation. Concomitantly, increased N:P ratios by the coral host and algal symbionts suggest excess availability of nitrogen and a disruption of the nitrogen limitation within the coral holobiont. As nitrogen fixation is similarly stimulated in ocean warming scenarios, here we propose a refined coral bleaching model integrating the cascading effects of stimulated microbial nitrogen fixation. This model highlights the putative role of nitrogen-fixing microbes in coral holobiont functioning and breakdown.

  8. Sugar enrichment provides evidence for a role of nitrogen fixation in coral bleaching

    KAUST Repository

    Pogoreutz, Claudia

    2017-04-21

    The disruption of the coral-algae symbiosis (coral bleaching) due to rising sea surface temperatures has become an unprecedented global threat to coral reefs. Despite decades of research, our ability to manage mass bleaching events remains hampered by an incomplete mechanistic understanding of the processes involved. In this study, we induced a coral bleaching phenotype in the absence of heat and light stress by adding sugars. The sugar addition resulted in coral symbiotic breakdown accompanied by a fourfold increase of coral-associated microbial nitrogen fixation. Concomitantly, increased N:P ratios by the coral host and algal symbionts suggest excess availability of nitrogen and a disruption of the nitrogen limitation within the coral holobiont. As nitrogen fixation is similarly stimulated in ocean warming scenarios, here we propose a refined coral bleaching model integrating the cascading effects of stimulated microbial nitrogen fixation. This model highlights the putative role of nitrogen-fixing microbes in coral holobiont functioning and breakdown.

  9. Coral Bleaching and Associated Mortality at Mayotte, Western Indian ...

    African Journals Online (AJOL)

    Mamoudzou 97600, Mayotte. Keywords: coral, bleaching, mortality, Mayotte, Western Indian Ocean. Abstract—Bleaching and associated coral mortality were assessed on fringing and barrier reefs on the north and east coasts of Mayotte from 1-24 May 2010. Major bleaching was encountered; nearly 80% of the corals were ...

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

    Science.gov (United States)

    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.

  11. Decline of coral reefs during late Paleocene to early Eocene global warming

    OpenAIRE

    Scheibner , C.; Speijer , R. P.

    2007-01-01

    International audience; Since the 1980s the frequency of warming events has intensified and simultaneously widespread coral bleaching, and enhanced coral mortality have been observed. Yet, it remains unpredictable how tropical coral reef communities will react to prolonged adverse conditions. Possibly, coral reef systems are sufficiently robust to withstand continued environmental pressures. But if coral mortality increases, what will platform communities of the future look like? The co-evolu...

  12. Variable responses of benthic communities to anomalously warm sea temperatures on a high-latitude coral reef.

    Science.gov (United States)

    Bridge, Tom C L; Ferrari, Renata; Bryson, Mitch; Hovey, Renae; Figueira, Will F; Williams, Stefan B; Pizarro, Oscar; Harborne, Alastair R; Byrne, Maria

    2014-01-01

    High-latitude reefs support unique ecological communities occurring at the biogeographic boundaries between tropical and temperate marine ecosystems. Due to their lower ambient temperatures, they are regarded as potential refugia for tropical species shifting poleward due to rising sea temperatures. However, acute warming events can cause rapid shifts in the composition of high-latitude reef communities, including range contractions of temperate macroalgae and bleaching-induced mortality in corals. While bleaching has been reported on numerous high-latitude reefs, post-bleaching trajectories of benthic communities are poorly described. Consequently, the longer-term effects of thermal anomalies on high-latitude reefs are difficult to predict. Here, we use an autonomous underwater vehicle to conduct repeated surveys of three 625 m(2) plots on a coral-dominated high-latitude reef in the Houtman Abrolhos Islands, Western Australia, over a four-year period spanning a large-magnitude thermal anomaly. Quantification of benthic communities revealed high coral cover (>70%, comprising three main morphospecies) prior to the bleaching event. Plating Montipora was most susceptible to bleaching, but in the plot where it was most abundant, coral cover did not change significantly because of post-bleaching increases in branching Acropora. In the other two plots, coral cover decreased while macroalgal cover increased markedly. Overall, coral cover declined from 73% to 59% over the course of the study, while macroalgal cover increased from 11% to 24%. The significant differences in impacts and post-bleaching trajectories among plots underline the importance of understanding the underlying causes of such variation to improve predictions of how climate change will affect reefs, especially at high-latitudes.

  13. Variable responses of benthic communities to anomalously warm sea temperatures on a high-latitude coral reef.

    Directory of Open Access Journals (Sweden)

    Tom C L Bridge

    Full Text Available High-latitude reefs support unique ecological communities occurring at the biogeographic boundaries between tropical and temperate marine ecosystems. Due to their lower ambient temperatures, they are regarded as potential refugia for tropical species shifting poleward due to rising sea temperatures. However, acute warming events can cause rapid shifts in the composition of high-latitude reef communities, including range contractions of temperate macroalgae and bleaching-induced mortality in corals. While bleaching has been reported on numerous high-latitude reefs, post-bleaching trajectories of benthic communities are poorly described. Consequently, the longer-term effects of thermal anomalies on high-latitude reefs are difficult to predict. Here, we use an autonomous underwater vehicle to conduct repeated surveys of three 625 m(2 plots on a coral-dominated high-latitude reef in the Houtman Abrolhos Islands, Western Australia, over a four-year period spanning a large-magnitude thermal anomaly. Quantification of benthic communities revealed high coral cover (>70%, comprising three main morphospecies prior to the bleaching event. Plating Montipora was most susceptible to bleaching, but in the plot where it was most abundant, coral cover did not change significantly because of post-bleaching increases in branching Acropora. In the other two plots, coral cover decreased while macroalgal cover increased markedly. Overall, coral cover declined from 73% to 59% over the course of the study, while macroalgal cover increased from 11% to 24%. The significant differences in impacts and post-bleaching trajectories among plots underline the importance of understanding the underlying causes of such variation to improve predictions of how climate change will affect reefs, especially at high-latitudes.

  14. An assessment of global warming stress on Caribbean coral reef ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Atwood, D.K.; Hendec, J.C.; Mendez, A. (NOAA, Miami, FL (USA). Atlantic Oceanography and Meteorology Laboratory)

    1992-07-01

    There is evidence that stress on coral reef ecosystems in the Caribbean region is increasing. Recently numerous authors have stated that the major stress results from 'abnormally high' seasonal sea surface temperatures (SST) and have implicated global warming as a cause, stating that recent episodes of coral bleaching result therefrom. However, an analysis of available SST data sets shows no discernible warming trend that could cause an increase in coral bleaching. Given the lack of long-term records synoptic with observations of coral ecosystem health, there is insufficient evidence available to label temperatures observed in coincidence with recent regional bleaching events as 'abnormally' high.

  15. An assessment of global warming stress on Caribbean coral reef ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Atwood, D K; Hendec, J C; Mendez, A [NOAA, Miami, FL (USA). Atlantic Oceanography and Meteorology Laboratory

    1992-07-01

    There is evidence that stress on coral reef ecosystems in the Caribbean region is increasing. Recently numerous authors have stated that the major stress results from 'abnormally high' seasonal sea surface temperatures (SST) and have implicated global warming as a cause, stating that recent episodes of coral bleaching result therefrom. However, an analysis of available SST data sets shows no discernible warming trend that could cause an increase in coral bleaching. Given the lack of long-term records synoptic with observations of coral ecosystem health, there is insufficient evidence available to label temperatures observed in coincidence with recent regional bleaching events as 'abnormally' high.

  16. Seychelles Lagoon Provides Corals with a Refuge from Bleaching

    Directory of Open Access Journals (Sweden)

    David Iluz

    2008-01-01

    Full Text Available An extensive bleaching event in the summer of the year 1997-1998 affected most reefs along East Africa's shores. In the aftermath of that episode, the reefs of Île Alphonse in the Seychelles were examined and it was found that reefs along the seaward slopes of the island lost >95% of their branching coral colonies, with considerably higher survival of massive species. Île Alphonse features a nearly circular shallow lagoon, with steep seaward slopes. Contrary to our expectations, mortality in the warmer lagoon was far lower than of coral colonies on the surrounding slopes, bathed in deeper and cooler waters. We suggest that corals in the lagoon were protected from UV radiation by leachate stemming from seagrass leaves steeped in the lagoon. Our measurements in the lagoon showed a strong attenuation of ultraviolet radiation, not observed in the waters outside the lagoon, and laboratory examination confirmed that the strong UV absorption of substances leached into seawater from decomposing leaves of the seagrass Thalassodendron (=Cymodocea testudinaceum. Our findings demonstrate the synergism between elevated seawater temperature and UV radiation in triggering bleaching on shallow reefs.

  17. Seychelles Lagoon Provides Corals with a Refuge from Bleaching

    International Nuclear Information System (INIS)

    Iluz, D.; Chadwick, N.E.; Hoffman, R.; Dubinsky, Z.; Vago, R.; Chadwick, N.E.; Chadwick, N.E.

    2008-01-01

    An extensive bleaching event in the summer of the year 1997-1998 affected most reefs along East Africa's shores. In the aftermath of that episode, the reefs of Ile Alphonse in the Seychelles were examined and it was found that reefs along the seaward slopes of the island lost >95% of their branching coral colonies, with considerably higher survival of massive species. Ile Alphonse features a nearly circular shallow lagoon, with steep seaward slopes. Contrary to our expectations, mortality in the warmer lagoon was far lower than of coral colonies on the surrounding slopes, bathed in deeper and cooler waters. We suggest that corals in the lagoon were protected from UV radiation by leachate stemming from sea grass leaves steeped in the lagoon. Our measurements in the lagoon showed a strong attenuation of ultraviolet radiation, no observed in the waters outside the lagoon, and laboratory examination confirmed that the strong UV absorption of substances leached into seawater from decomposing leaves of the sea grass Thalassodendron (=Cymodocea) testudinaceum. Our findings demonstrate the synergism between elevated seawater temperature and UV radiation in triggering bleaching on shallow reefs.

  18. Transcriptomic responses to darkness stress point to common coral bleaching mechanisms

    Science.gov (United States)

    Desalvo, M. K.; Estrada, A.; Sunagawa, S.; Medina, Mónica

    2012-03-01

    Coral bleaching occurs in response to numerous abiotic stressors, the ecologically most relevant of which is hyperthermic stress due to increasing seawater temperatures. Bleaching events can span large geographic areas and are currently a salient threat to coral reefs worldwide. Much effort has been focused on understanding the molecular and cellular events underlying bleaching, and these studies have mainly utilized heat and light stress regimes. In an effort to determine whether different stressors share common bleaching mechanisms, we used complementary DNA (cDNA) microarrays for the corals Acropora palmata and Montastraea faveolata (containing >10,000 features) to measure differential gene expression during darkness stress. Our results reveal a striking transcriptomic response to darkness in A. palmata involving chaperone and antioxidant up-regulation, growth arrest, and metabolic modifications. As these responses were previously measured during thermal stress, our results suggest that different stressors may share common bleaching mechanisms. Furthermore, our results point to hypoxia and endoplasmic reticulum stress as critical cellular events involved in molecular bleaching mechanisms. On the other hand, we identified a meager transcriptomic response to darkness in M. faveolata where gene expression differences between host colonies and sampling locations were greater than differences between control and stressed fragments. This and previous coral microarray studies reveal the immense range of transcriptomic responses that are possible when studying two coral species that differ greatly in their ecophysiology, thus pointing to the importance of comparative approaches in forecasting how corals will respond to future environmental change.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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 (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.

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

    Directory of Open Access Journals (Sweden)

    Elisa Bayraktarov

    Full Text Available 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.

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

    Science.gov (United States)

    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. Copyright 2010 Elsevier Ltd. All rights reserved.

  3. Spatial variation in coral reef fish and benthic communities in the central Saudi Arabian Red Sea

    KAUST Repository

    Khalil, Maha T.

    2017-06-06

    Local-scale ecological information is critical as a sound basis for spatial management and conservation and as support for ongoing research in relatively unstudied areas. We conducted visual surveys of fish and benthic communities on nine reefs (3–24 km from shore) in the Thuwal area of the central Saudi Arabian Red Sea. Fish biomass increased with increasing distance from shore, but was generally low compared to reefs experiencing minimal human influence around the world. All reefs had a herbivore-dominated trophic structure and few top predators, such as sharks, jacks, or large groupers. Coral cover was considerably lower on inshore reefs, likely due to a 2010 bleaching event. Community analyses showed inshore reefs to be characterized by turf algae, slower-growing corals, lower herbivore diversity, and highly abundant turf-farming damselfishes. Offshore reefs had more planktivorous fishes, a more diverse herbivore assemblage, and faster-growing corals. All reefs appear to be impacted by overfishing, and inshore reefs seem more vulnerable to thermal bleaching. The study provides a description of the spatial variation in biomass and community structure in the central Saudi Arabian Red Sea and provides a basis for spatial prioritization and subsequent marine protected area design in Thuwal.

  4. Spatial variation in coral reef fish and benthic communities in the central Saudi Arabian Red Sea.

    Science.gov (United States)

    Khalil, Maha T; Bouwmeester, Jessica; Berumen, Michael L

    2017-01-01

    Local-scale ecological information is critical as a sound basis for spatial management and conservation and as support for ongoing research in relatively unstudied areas. We conducted visual surveys of fish and benthic communities on nine reefs (3-24 km from shore) in the Thuwal area of the central Saudi Arabian Red Sea. Fish biomass increased with increasing distance from shore, but was generally low compared to reefs experiencing minimal human influence around the world. All reefs had a herbivore-dominated trophic structure and few top predators, such as sharks, jacks, or large groupers. Coral cover was considerably lower on inshore reefs, likely due to a 2010 bleaching event. Community analyses showed inshore reefs to be characterized by turf algae, slower-growing corals, lower herbivore diversity, and highly abundant turf-farming damselfishes. Offshore reefs had more planktivorous fishes, a more diverse herbivore assemblage, and faster-growing corals . All reefs appear to be impacted by overfishing, and inshore reefs seem more vulnerable to thermal bleaching. The study provides a description of the spatial variation in biomass and community structure in the central Saudi Arabian Red Sea and provides a basis for spatial prioritization and subsequent marine protected area design in Thuwal.

  5. Spatial variation in coral reef fish and benthic communities in the central Saudi Arabian Red Sea

    Directory of Open Access Journals (Sweden)

    Maha T. Khalil

    2017-06-01

    Full Text Available Local-scale ecological information is critical as a sound basis for spatial management and conservation and as support for ongoing research in relatively unstudied areas. We conducted visual surveys of fish and benthic communities on nine reefs (3–24 km from shore in the Thuwal area of the central Saudi Arabian Red Sea. Fish biomass increased with increasing distance from shore, but was generally low compared to reefs experiencing minimal human influence around the world. All reefs had a herbivore-dominated trophic structure and few top predators, such as sharks, jacks, or large groupers. Coral cover was considerably lower on inshore reefs, likely due to a 2010 bleaching event. Community analyses showed inshore reefs to be characterized by turf algae, slower-growing corals, lower herbivore diversity, and highly abundant turf-farming damselfishes. Offshore reefs had more planktivorous fishes, a more diverse herbivore assemblage, and faster-growing corals. All reefs appear to be impacted by overfishing, and inshore reefs seem more vulnerable to thermal bleaching. The study provides a description of the spatial variation in biomass and community structure in the central Saudi Arabian Red Sea and provides a basis for spatial prioritization and subsequent marine protected area design in Thuwal.

  6. Spatial variation in coral reef fish and benthic communities in the central Saudi Arabian Red Sea

    KAUST Repository

    Khalil, Maha T.; Bouwmeester, Jessica; Berumen, Michael L.

    2017-01-01

    Local-scale ecological information is critical as a sound basis for spatial management and conservation and as support for ongoing research in relatively unstudied areas. We conducted visual surveys of fish and benthic communities on nine reefs (3–24 km from shore) in the Thuwal area of the central Saudi Arabian Red Sea. Fish biomass increased with increasing distance from shore, but was generally low compared to reefs experiencing minimal human influence around the world. All reefs had a herbivore-dominated trophic structure and few top predators, such as sharks, jacks, or large groupers. Coral cover was considerably lower on inshore reefs, likely due to a 2010 bleaching event. Community analyses showed inshore reefs to be characterized by turf algae, slower-growing corals, lower herbivore diversity, and highly abundant turf-farming damselfishes. Offshore reefs had more planktivorous fishes, a more diverse herbivore assemblage, and faster-growing corals. All reefs appear to be impacted by overfishing, and inshore reefs seem more vulnerable to thermal bleaching. The study provides a description of the spatial variation in biomass and community structure in the central Saudi Arabian Red Sea and provides a basis for spatial prioritization and subsequent marine protected area design in Thuwal.

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

    NARCIS (Netherlands)

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

    2008-01-01

    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

  8. NOAA Coral Reef Watch Operational Near-real-time Twice-weekly Global 50 km Satellite Coral Bleaching Thermal Stress Monitoring Product Suite

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA Coral Reef Watch program produces a suite of near-real-time global 50 km monitoring products, based on sea surface temperature (SST) observations from NOAA's...

  9. Repeated Thermal Stress, Shading, and Directional Selection in the Florida Reef Tract

    Directory of Open Access Journals (Sweden)

    Robert van Woesik

    2017-06-01

    Full Text Available Over the last three decades reef corals have been subjected to an unprecedented frequency and intensity of thermal-stress events, which have led to extensive coral bleaching, disease, and mortality. Over the next century, the climate is predicted to drive sea-surface temperatures to even higher levels, consequently increasing the risk of mass bleaching and disease outbreaks. Yet, there is considerable temporal and spatial variation in coral bleaching and in disease prevalence. Using data collected from 2,398 sites along the Florida reef tract from 2005 to 2015, this study examined the temporal and spatial patterns of coral bleaching and disease in relation to coral-colony size, depth, temperature, and chlorophyll-a concentrations. The results show that coral bleaching was most prevalent during the warmest years in 2014 and 2015, and disease was also most prevalent in 2010, 2014, and 2015. Although the majority of the corals surveyed were found in habitats with low chlorophyll-a concentrations, and high irradiance, these same habitats showed the highest prevalence of coral bleaching and disease outbreaks during thermal-stress events. These results suggest that directional selection in a warming ocean may favor corals able to tolerate inshore, shaded environments with high turbidity and productivity.

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

    Directory of Open Access Journals (Sweden)

    Adam D Hughes

    Full Text Available 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

  11. Forecasted coral reef decline in marine biodiversity hotspots under climate change.

    Science.gov (United States)

    Descombes, Patrice; Wisz, Mary S; Leprieur, Fabien; Parravicini, Valerianio; Heine, Christian; Olsen, Steffen M; Swingedouw, Didier; Kulbicki, Michel; Mouillot, David; Pellissier, Loïc

    2015-01-21

    Coral bleaching events threaten coral reef habitats globally and cause severe declines of local biodiversity and productivity. Related to high sea surface temperatures (SST), bleaching 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 corals during the Eocene may help to inform models forecasting the future of coral reefs. We coupled contemporary and Eocene coral occurrences with information on their respective climatic conditions to model the thermal niche of coral reefs and its potential response to projected climate change. We found that under the RCP8.5 climate change scenario, the global suitability for coral reefs may increase up to 16% by 2100, mostly due to improved suitability of higher latitudes. In contrast, in its current range, coral 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 coral reefs, including those that have been refugia in the past, spatially mismatch with future suitable areas for coral reefs posing challenges to conservation actions under climate change. © 2015 John Wiley & Sons Ltd.

  12. Biomass and Abundance of Herbivorous Fishes on Coral Reefs off ...

    African Journals Online (AJOL)

    effects of fishing intensity, reef geomorphology and benthic cover. Distance from the .... on herbivorous fish communities relevant to the proposed ... fragments, nearshore coastal fringing reefs ..... Over-fishing and coral bleaching pose the most ...

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

    Science.gov (United States)

    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

  14. Connectivity and systemic resilience of the Great Barrier Reef.

    Directory of Open Access Journals (Sweden)

    Karlo Hock

    2017-11-01

    Full Text Available Australia's iconic Great Barrier Reef (GBR continues to suffer from repeated impacts of cyclones, coral bleaching, and outbreaks of the coral-eating crown-of-thorns starfish (COTS, losing much of its coral cover in the process. This raises the question of the ecosystem's systemic resilience and its ability to rebound after large-scale population loss. Here, we reveal that around 100 reefs of the GBR, or around 3%, have the ideal properties to facilitate recovery of disturbed areas, thereby imparting a level of systemic resilience and aiding its continued recovery. These reefs (1 are highly connected by ocean currents to the wider reef network, (2 have a relatively low risk of exposure to disturbances so that they are likely to provide replenishment when other reefs are depleted, and (3 have an ability to promote recovery of desirable species but are unlikely to either experience or spread COTS outbreaks. The great replenishment potential of these 'robust source reefs', which may supply 47% of the ecosystem in a single dispersal event, emerges from the interaction between oceanographic conditions and geographic location, a process that is likely to be repeated in other reef systems. Such natural resilience of reef systems will become increasingly important as the frequency of disturbances accelerates under climate change.

  15. The effects of sea surface temperature anomalies on oceanic coral reef systems in the southwestern tropical Atlantic

    Science.gov (United States)

    Ferreira, B. P.; Costa, M. B. S. F.; Coxey, M. S.; Gaspar, A. L. B.; Veleda, D.; Araujo, M.

    2013-06-01

    In 2010, high sea surface temperatures that were recorded in several parts of the world and caused coral bleaching and coral mortality were also recorded in the southwest Atlantic Ocean, between latitudes 0°S and 8°S. This paper reports on coral bleaching and diseases in Rocas Atoll and Fernando de Noronha archipelago and examines their relationship with sea surface temperature (SST) anomalies recorded by PIRATA buoys located at 8°S30°W, 0°S35°W, and 0°S23°W. Adjusted satellite data were used to derive SST climatological means at buoy sites and to derive anomalies at reef sites. The whole region was affected by the elevated temperature anomaly that persisted through 2010, reaching 1.67 °C above average at reef sites and 1.83 °C above average at buoys sites. A significant positive relationship was found between the percentage of coral bleaching that was observed on reef formations and the corresponding HotSpot SST anomaly recorded by both satellite and buoys. These results indicate that the warming observed in the ocean waters was followed by a warming at the reefs. The percentage of bleached corals persisting after the subsidence of the thermal stress, and disease prevalence increased through 2010, after two periods of thermal stress. The in situ temperature anomaly observed during the 2009-2010 El Niño event was equivalent to the anomaly observed during the 1997-1998 El Niño event, explaining similar bleaching intensity. Continued monitoring efforts are necessary to further assess the relationship between bleaching severity and PIRATA SST anomalies and improve the use of this new dataset in future regional bleaching predictions.

  16. Towed-Diver Observations in the Main Hawaiian Islands to Assess the Mass Coral Bleaching Event in November 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A team from the Pacific Islands Fisheries Science Center (PIFSC), Coral Reef Ecosystem Program (CREP) deployed on a two-week research cruise in November 2015 to...

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

    OpenAIRE

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

    2008-01-01

    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...

  18. Peroxy bleaches

    Energy Technology Data Exchange (ETDEWEB)

    Carson, P.A. [Unilever Research, Port Sunlight Laboratory (United States) and Chemistry Department, University of Manchester, Institute of Science and Technology (United States)]. E-mail: pcarson2005@aol.com; Fairclough, C.S. [Unilever Research, Port Sunlight Laboratory (United States); Mauduit, C. [Chemistry Department, University of Manchester, Institute of Science and Technology (United States); Colsell, M. [Chemistry Department, University of Manchester, Institute of Science and Technology (United States)

    2006-08-25

    Fabric laundering is now a sophisticated chemical process involving a variety of operations including bleaching. The chemistry of peroxy bleaches is described including the use of novel organic compounds to provide effective bleaching at the lower temperatures of modern wash cycles. The instability of peroxy compounds is illustrated using cameo case histories to relate theory and practice. Techniques available for determining their thermochemistry are summarised. A model is provided for hazard and risk assessment of development projects in general (particularly those involving new molecules, processes or formulations) from ideas phase through exploratory laboratory investigations to pilot plant scale-up and eventual manufacture and commercial exploitation. This paper is a prelude to Part 2, which describes the determination of thermodynamic and kinetic properties of peroxy bleaches and discusses the implication of the results in terms of precautions for their safe storage and incorporation into detergent formulations during processing.

  19. Peroxy bleaches

    International Nuclear Information System (INIS)

    Carson, P.A.; Fairclough, C.S.; Mauduit, C.; Colsell, M.

    2006-01-01

    Fabric laundering is now a sophisticated chemical process involving a variety of operations including bleaching. The chemistry of peroxy bleaches is described including the use of novel organic compounds to provide effective bleaching at the lower temperatures of modern wash cycles. The instability of peroxy compounds is illustrated using cameo case histories to relate theory and practice. Techniques available for determining their thermochemistry are summarised. A model is provided for hazard and risk assessment of development projects in general (particularly those involving new molecules, processes or formulations) from ideas phase through exploratory laboratory investigations to pilot plant scale-up and eventual manufacture and commercial exploitation. This paper is a prelude to Part 2, which describes the determination of thermodynamic and kinetic properties of peroxy bleaches and discusses the implication of the results in terms of precautions for their safe storage and incorporation into detergent formulations during processing

  20. State of the coralline reefs

    International Nuclear Information System (INIS)

    Garzon Ferreira, Jaime; Rodriguez Ramirez, Alberto; Bejarano Chavarro, Sonia; Navas Camacho, Raul; Reyes Nivia, Catalina

    2002-01-01

    A diagnosis is made based primarily on the data obtained inside the national system of monitoring of coralline reefs in Colombia, under the coordination of the INVEMAR and with the support of several institutions. The paper does a diagnostic of the covering of the reef substrate, bleaching and coralline illnesses, wealth and abundance of fishes among other topics

  1. The coral reef crisis: the critical importance of<350 ppm CO2.

    Science.gov (United States)

    Veron, J E N; Hoegh-Guldberg, O; Lenton, T M; Lough, J M; Obura, D O; Pearce-Kelly, P; Sheppard, C R C; Spalding, M; Stafford-Smith, M G; Rogers, A D

    2009-10-01

    Temperature-induced mass coral bleaching causing mortality on a wide geographic scale started when atmospheric CO(2) levels exceeded approximately 320 ppm. When CO(2) levels reached approximately 340 ppm, sporadic but highly destructive mass bleaching occurred in most reefs world-wide, often associated with El Niño events. Recovery was dependent on the vulnerability of individual reef areas and on the reef's previous history and resilience. At today's level of approximately 387 ppm, allowing a lag-time of 10 years for sea temperatures to respond, most reefs world-wide are committed to an irreversible decline. Mass bleaching will in future become annual, departing from the 4 to 7 years return-time of El Niño events. Bleaching will be exacerbated by the effects of degraded water-quality and increased severe weather events. In addition, the progressive onset of ocean acidification will cause reduction of coral growth and retardation of the growth of high magnesium calcite-secreting coralline algae. If CO(2) levels are allowed to reach 450 ppm (due to occur by 2030-2040 at the current rates), reefs will be in rapid and terminal decline world-wide from multiple synergies arising from mass bleaching, ocean acidification, and other environmental impacts. Damage to shallow reef communities will become extensive with consequent reduction of biodiversity followed by extinctions. Reefs will cease to be large-scale nursery grounds for fish and will cease to have most of their current value to humanity. There will be knock-on effects to ecosystems associated with reefs, and to other pelagic and benthic ecosystems. Should CO(2) levels reach 600 ppm reefs will be eroding geological structures with populations of surviving biota restricted to refuges. Domino effects will follow, affecting many other marine ecosystems. This is likely to have been the path of great mass extinctions of the past, adding to the case that anthropogenic CO(2) emissions could trigger the Earth's sixth

  2. Modeling regional coral reef responses to global warming and changes in ocean chemistry: Caribbean case study

    Science.gov (United States)

    Buddemeier, R.W.; Lane, D.R.; Martinich, J.A.

    2011-01-01

    Climatic change threatens the future of coral reefs in the Caribbean and the important ecosystem services they provide. We used a simulation model [Combo ("COral Mortality and Bleaching Output")] to estimate future coral cover in the part of the eastern Caribbean impacted by a massive coral bleaching event in 2005. Combo calculates impacts of future climate change on coral reefs by combining impacts from long-term changes in average sea surface temperature (SST) and ocean acidification with impacts from episodic high temperature mortality (bleaching) events. We used mortality and heat dose data from the 2005 bleaching 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 coral reefs in the eastern Caribbean. For three different emissions scenarios from the Intergovernmental Panel on Climate Change (IPCC; B1, A1B, and A1FI), coral 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 corals gain an additional 1-1. 5??C of heat tolerance through a shift in the algae that live in the coral tissue, coral cover above 5% is prolonged until 2065. Additional impacts such as storms or anthropogenic damage could result in declines in coral 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 bleaching to save as many remnant populations of corals as possible in the face of projected wide-spread coral loss. ?? 2011 The Author(s).

  3. Quantifying and Valuing Potential Climate Change Impacts on Coral Reefs in the United States

    Science.gov (United States)

    Wobus, C. W.; Lane, D.; Buddemeier, R. W.; Ready, R. C.; Shouse, K. C.; Martinich, J.

    2012-12-01

    Global climate change presents a two-pronged threat to coral reef ecosystems: increasing sea surface temperatures will increase the likelihood of episodic bleaching events, while increasing ocean carbon dioxide concentrations will change the carbonate chemistry that drives coral growth. Because coral reefs have important societal as well as ecological benefits, climate change mitigation policies that ameliorate these impacts may create substantial economic value. We present a model that evaluates both the ecological and the economic impacts of climate change on coral reefs in the United States. We use a coral reef mortality and bleaching model to project future coral reef declines under a range of climate change policy scenarios for south Florida, Puerto Rico and Hawaii. Using a benefits transfer approach, the outputs from the physical model are then used to quantify the economic impacts of these coral reef declines for each of these regions. We find that differing climate change trajectories create substantial changes in projected coral cover and value for Hawaii, but that the ecological and economic benefits of more stringent emissions scenarios are less clear for Florida and Puerto Rico. Overall, our results indicate that the effectiveness of climate change mitigation policies may be region-specific, but that these policies could result in a net increase of nearly $10 billion in economic value from coral reef-related recreational activities alone, over the 21st century.

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

    Science.gov (United States)

    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...

  5. Species-specific interactions between algal endosymbionts and coral hosts define their bleaching response to heat and light stress

    DEFF Research Database (Denmark)

    Abrego, David; Ulstrup, Karin E; Willis, Bette L

    2008-01-01

    The impacts of warming seas on the frequency and severity of bleaching events are well documented, but the potential for different Symbiodinium types to enhance the physiological tolerance of reef corals is not well understood. Here we compare the functionality and physiological properties...... and a potential role for host factors in determining the physiological performance of reef corals....... of juvenile corals when experimentally infected with one of two homologous Symbiodinium types and exposed to combined heat and light stress. A suite of physiological indicators including chlorophyll a fluorescence, oxygen production and respiration, as well as pigment concentration consistently demonstrated...

  6. Pattern and intensity of human impact on coral reefs depend on depth along the reef profile and on the descriptor adopted

    Science.gov (United States)

    Nepote, Ettore; Bianchi, Carlo Nike; Chiantore, Mariachiara; Morri, Carla; Montefalcone, Monica

    2016-09-01

    Coral reefs are threatened by multiple global and local disturbances. The Maldives, already heavily hit by the 1998 mass bleaching event, are currently affected also by growing tourism and coastal development that may add to global impacts. Most of the studies investigating effects of local disturbances on coral reefs assessed the response of communities along a horizontal distance from the impact source. This study investigated the status of a Maldivian coral reef around an island where an international touristic airport has been recently (2009-2011) built, at different depths along the reef profile (5-20 m depth) and considering the change in the percentage of cover of five different non-taxonomic descriptors assessed through underwater visual surveys: hard corals, soft corals, other invertebrates, macroalgae and abiotic attributes. Eight reefs in areas not affected by any coastal development were used as controls and showed a reduction of hard coral cover and an increase of abiotic attributes (i.e. sand, rock, coral rubble) at the impacted reef. However, hard coral cover, the most widely used descriptor of coral reef health, was not sufficient on its own to detect subtle indirect effects that occurred down the reef profile. Selecting an array of descriptors and considering different depths, where corals may find a refuge from climate impacts, could guide the efforts of minimising local human pressures on coral reefs.

  7. Shifting paradigms in restoration of the world's coral reefs.

    Science.gov (United States)

    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

    2017-09-01

    Many ecosystems around the world are rapidly deteriorating due to both local and global pressures, and perhaps none so precipitously as coral reefs. Management of coral 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 coral reefs. Despite these initiatives, the health and abundance of corals 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 coral microbiome) as a means to enhance environmental stress tolerance of corals and the success of coral reef restoration efforts. The 2014-2016 global coral bleaching 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 corals and coral reef ecosystems, and propose a decision tree for incorporating assisted evolution into restoration initiatives to enhance climate resilience of coral reefs. © 2017 John Wiley & Sons Ltd.

  8. Coral-bacterial communities before and after a coral mass spawning event on Ningaloo Reef.

    Directory of Open Access Journals (Sweden)

    Janja Ceh

    Full Text Available Bacteria associated with three coral species, Acropora tenuis, Pocillopora damicornis and Tubastrea faulkneri, were assessed before and after coral mass spawning on Ningaloo Reef in Western Australia. Two colonies of each species were sampled before and after the mass spawning event and two additional samples were collected for P. damicornis after planulation. A variable 470 bp region of the 16 S rRNA gene was selected for pyrosequencing to provide an understanding of potential variations in coral-associated bacterial diversity and community structure. Bacterial diversity increased for all coral species after spawning as assessed by Chao1 diversity indicators. Minimal changes in community structure were observed at the class level and data at the taxonomical level of genus incorporated into a PCA analysis indicated that despite bacterial diversity increasing after spawning, coral-associated community structure did not shift greatly with samples grouped according to species. However, interesting changes could be detected from the dataset; for example, α-Proteobacteria increased in relative abundance after coral spawning and particularly the Roseobacter clade was found to be prominent in all coral species, indicating that this group may be important in coral reproduction.

  9. Assessing Coral Community Recovery from Coral Bleaching by ...

    African Journals Online (AJOL)

    The densities of small colonies were lowest at the northern sites, and small colonies of genera of corals that suffered from high bleaching and mortality during the El Niño Southern Oscillation in 1998 were less abundant in the north. These northern reefs are relatively isolated from sources of coral larvae from reefs in the ...

  10. Mesopredator trophodynamics on thermally stressed coral reefs

    Science.gov (United States)

    Hempson, Tessa N.; Graham, Nicholas A. J.; MacNeil, M. Aaron; Hoey, Andrew S.; Almany, Glenn R.

    2018-03-01

    Ecosystems are becoming vastly modified through disturbance. In coral reef ecosystems, the differential susceptibility of coral taxa to climate-driven bleaching is predicted to shift coral assemblages towards reefs with an increased relative abundance of taxa with high thermal tolerance. Many thermally tolerant coral species are characterised by low structural complexity, with reduced habitat niche space for the small-bodied coral reef fishes on which piscivorous mesopredators feed. This study used a patch reef array to investigate the potential impacts of climate-driven shifts in coral assemblages on the trophodynamics of reef mesopredators and their prey communities. The `tolerant' reef treatment consisted only of coral taxa of low susceptibility to bleaching, while `vulnerable' reefs included species of moderate to high thermal vulnerability. `Vulnerable' reefs had higher structural complexity, and the fish assemblages that established on these reefs over 18 months had higher species diversity, abundance and biomass than those on `tolerant' reefs. Fish assemblages on `tolerant' reefs were also more strongly influenced by the introduction of a mesopredator ( Cephalopholis boenak). Mesopredators on `tolerant' reefs had lower lipid content in their muscle tissue by the end of the 6-week experiment. Such sublethal energetic costs can compromise growth, fecundity, and survivorship, resulting in unexpected population declines in long-lived mesopredators. This study provides valuable insight into the altered trophodynamics of future coral reef ecosystems, highlighting the potentially increased vulnerability of reef fish assemblages to predation as reef structure declines, and the cost of changing prey availability on mesopredator condition.

  11. Coral bleaching independent of photosynthetic activity.

    Science.gov (United States)

    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. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. 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

    Science.gov (United States)

    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.

  13. Coral Reef Watch, Hotspots, 50 km

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA Coral Reef Watch provides Coral Bleaching hotspot maps derived from NOAA's Polar Operational Environmental Satellites (POES). This data provides global area...

  14. A citizen science approach to monitoring bleaching in the zoantharian Palythoa tuberculosa

    KAUST Repository

    Parkinson, John Everett

    2016-03-28

    Coral reef bleaching events are expected to become more frequent and severe in the near future as climate changes. The zoantharian Palythoa tuberculosa bleaches earlier than many scleractinian corals and may serve as an indicator species. Basic monitoring of such species could help to detect and even anticipate bleaching events, especially in areas where more sophisticated approaches that rely on buoy or satellite measurements of sea surface temperature are unavailable or too coarse. One simple and inexpensive monitoring method involves training volunteers to record observations of host color as a proxy for symbiosis quality. Here, we trained university students to take the ‘color fingerprint’ of a reef by assessing the color of multiple randomly selected colonies of P. tuberculosa at one time point in Okinawa Island, Japan. We tested the reliability of the students’ color scores and whether they matched expectations based on previous monthly monitoring of tagged colonies at the same locations. We also measured three traditional metrics of symbiosis quality for comparison: symbiont morphological condition, cell density, and chlorophyll a content. We found that P. tuberculosa color score, although highly correlated among observers, provided little predictive power for the other variables. This was likely due to inherent variation in colony color among generally healthy zoantharians in midwinter, as well as low sample size and brief training owing to the course structure. Despite certain limitations of P. tuberculosa as a focal organism, the citizen science approach to color monitoring has promise, and we outline steps that could improve similar efforts in the future.

  15. Local extinction of a coral reef fish explained by inflexible prey choice

    Science.gov (United States)

    Brooker, R. M.; Munday, P. L.; Brandl, S. J.; Jones, G. P.

    2014-12-01

    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 coral reefs, coral bleaching is an increasingly frequent cause of coral mortality that can result in dramatic changes to coral community composition. Coral-associated fishes are often specialised on a limited suite of coral species and are therefore sensitive to these changes. This study documents the local extinction of a corallivorous reef fish, Oxymonacanthus longirostris, following a mass bleaching event that altered the species composition of associated coral communities. Local extinction only occurred on reefs that also completely lost a key prey species, Acropora millepora, even though coral cover remained high. In an experimental test, fish continued to select bleached A. millepora over the healthy, but less-preferred prey species that resisted bleaching. These results suggest that behavioural inflexibility may limit the ability of specialists to cope with even subtle changes to resource availability.

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

    Science.gov (United States)

    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.

  17. Coralline reefs classification in Banco Chinchorro, Mexico

    Science.gov (United States)

    Contreras-Silva, Ameris I.; López-Caloca, Alejandra A.

    2009-09-01

    The coralline reefs in Banco Chinchorro, Mexico, are part of the great reef belt of the western Atlantic. This reef complex is formed by an extensive coralline structure with great biological richness and diversity of species. These colonies are considered highly valuable ecologically, economically, socially and culturally, and they also inherently provide biological services. Fishing and scuba diving have been the main economic activities in this area for decades. However, in recent years, there has been a bleaching process and a decrease of the coral colonies in Quintana Roo, Mexico. This drop is caused mainly by the production activities performed in the oil platforms and the presence of hurricanes among other climatic events. The deterioration of the reef system can be analyzed synoptically using remote sensing. Thanks to this type of analysis, it is possible to have updated information of the reef conditions. In this paper, satellite imagery in Landsat TM and SPOT 5 is applied in the coralline reefs classification in the 1980- 2006 time period. Thus, an integral analysis of the optical components of the water surrounding the coralline reefs, such as on phytoplankton, sediments, yellow substance and even on the same water adjacent to the coral colonies, is performed. The use of a texture algorithm (Markov Random Field) was a key tool for their identification. This algorithm, does not limit itself to image segmentation, but also works on edge detection. In future work the multitemporal analysis of the results will determine the deterioration degree of these habitats and the conservation status of the coralline areas.

  18. Coral recovery may not herald the return of fishes on damaged coral reefs

    KAUST Repository

    Bellwood, David R.; Baird, Andrew Hamilton; Depczynski, Martial R.; Gonzá lez-Cabello, Alonso; Hoey, Andrew; Lefé vre, Carine D.; Tanner, Jennifer K.

    2012-01-01

    The dynamic nature of coral 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 coral bleaching 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-bleach configuration. This is despite coral abundances returning to, or exceeding, pre-bleach values. The post-bleach 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 bleaching 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 corals. © 2012 Springer-Verlag.

  19. Coral recovery may not herald the return of fishes on damaged coral reefs

    KAUST Repository

    Bellwood, David R.

    2012-03-25

    The dynamic nature of coral 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 coral bleaching 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-bleach configuration. This is despite coral abundances returning to, or exceeding, pre-bleach values. The post-bleach 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 bleaching 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 corals. © 2012 Springer-Verlag.

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

    Directory of Open Access Journals (Sweden)

    Stephen J Levas

    Full Text Available 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(13C of the skeletal, δ(13C, and δ(15N 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

  1. COLLABORATIVE GUIDE: A REEF MANAGER'S GUIDE TO ...

    Science.gov (United States)

    Innovative strategies to conserve the world's coral reefs are included in a new guide released today by NOAA, and the Australian Great Barrier Reef Marine Park Authority, with author contributions from a variety of international partners from government agencies, non-governmental organizations, and academic institutions. Referred to as A Reef Manager's Guide to Coral Bleaching, the guide will provide coral reef managers with the latest scientific information on the causes of coral bleaching and new management strategies for responding to this significant threat to coral reef ecosystems. Innovative strategies to conserve the world's coral reefs are included in a new guide released today by NOAA, and the Australian Great Barrier Reef Marine Park Authority, with author contributions from a variety of international partners from government agencies, non-governmental organizations, and academic institutions. Dr. Jordan West, of the National Center for Environmental Assessment, was a major contributor to the guide. Referred to as

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

    Science.gov (United States)

    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...

  3. Doom and boom on a resilient reef: climate change, algal overgrowth and coral recovery.

    Directory of Open Access Journals (Sweden)

    Guillermo Diaz-Pulido

    Full Text Available Coral reefs around the world are experiencing large-scale degradation, largely due to global climate change, overfishing, diseases and eutrophication. Climate change models suggest increasing frequency and severity of warming-induced coral bleaching events, with consequent increases in coral mortality and algal overgrowth. Critically, the recovery of damaged reefs will depend on the reversibility of seaweed blooms, generally considered to depend on grazing of the seaweed, and replenishment of corals by larvae that successfully recruit to damaged reefs. These processes usually take years to decades to bring a reef back to coral dominance.In 2006, mass bleaching of corals on inshore reefs of the Great Barrier Reef caused high coral mortality. Here we show that this coral mortality was followed by an unprecedented bloom of a single species of unpalatable seaweed (Lobophora variegata, colonizing dead coral skeletons, but that corals on these reefs recovered dramatically, in less than a year. Unexpectedly, this rapid reversal did not involve reestablishment of corals by recruitment of coral larvae, as often assumed, but depended on several ecological mechanisms previously underestimated.These mechanisms of ecological recovery included rapid regeneration rates of remnant coral tissue, very high competitive ability of the corals allowing them to out-compete the seaweed, a natural seasonal decline in the particular species of dominant seaweed, and an effective marine protected area system. Our study provides a key example of the doom and boom of a highly resilient reef, and new insights into the variability and mechanisms of reef resilience under rapid climate change.

  4. IMPACT OF BLEACHING STRESS ON THE FUNCTION OF THE OXYGEN EVOLVING COMPLEX OF ZOOXANTHELLAE FROM SCLERACTINIAN CORALS(1).

    Science.gov (United States)

    Hill, Ross; Ralph, Peter J

    2008-04-01

    Global climate change is leading to the rise of ocean temperatures and is triggering mass coral bleaching events on reefs around the world. The expulsion of the symbiotic dinoflagellate algae is believed to occur as a result of damage to the photosynthetic apparatus of these symbionts, although the specific site of initial impact is yet to be conclusively resolved. Here, the sensitivity of the oxygen evolving complex (OEC) to bleaching stress was studied as well as its natural variation between seasons. The artificial electron donor, diphenyl carbazide (DPC), was added to cultured, freshly isolated and expelled (bleaching treatments only) zooxanthellae suspensions. Chl a fluorescence and oxygen production measurements showed that upon addition of DPC, no restoration of diminished photochemical efficiency occurred under control or bleaching conditions. This result was consistent between 12 h and 5 d bleaching treatments on Pocilloporadamicornis, indicating that the OEC is not the primary site of damage, and that zooxanthellae expulsion from the host is a nonselective process with respect to the functioning of the OEC. Further experiments measuring fast induction curves (FICs) revealed that in both summer and winter, the temperature when OEC function was lost occurred between 7°C and 14°C above the sea surface temperature. FIC and oxygen production measurements of P. damicornis during exposure to bleaching stress demonstrated that the thermotolerance of the OEC increased above the temperature of the bleaching treatment over a 4 h period. This finding indicates that the OEC has the capacity to acclimate between seasons and remains functional at temperatures well above bleaching thresholds. © 2008 Phycological Society of America.

  5. A coral reef refuge in the Red Sea.

    Science.gov (United States)

    Fine, Maoz; Gildor, Hezi; Genin, Amatzia

    2013-12-01

    The stability and persistence of coral reefs in the decades to come is uncertain due to global warming and repeated bleaching 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 bleaching threshold of northern Red Sea corals and on the potential dispersal of coral 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 coral genotypes that are less susceptible to thermal stress in the northern Red Sea, delaying bleaching events in the GoA by at least a century. © 2013 John Wiley & Sons Ltd.

  6. Acoustic and biological trends on coral reefs off Maui, Hawaii

    Science.gov (United States)

    Kaplan, Maxwell B.; Lammers, Marc O.; Zang, Eden; Aran Mooney, T.

    2018-03-01

    Coral reefs are characterized by high biodiversity, and evidence suggests that reef soundscapes reflect local species assemblages. To investigate how sounds produced on a given reef relate to abiotic and biotic parameters and how that relationship may change over time, an observational study was conducted between September 2014 and January 2016 at seven Hawaiian reefs that varied in coral cover, rugosity, and fish assemblages. The reefs were equipped with temperature loggers and acoustic recording devices that recorded on a 10% duty cycle. Benthic and fish visual survey data were collected four times over the course of the study. On average, reefs ranged from 0 to 80% live coral cover, although changes between surveys were noted, in particular during the major El Niño-related bleaching event of October 2015. Acoustic analyses focused on two frequency bands (50-1200 and 1.8-20.5 kHz) that corresponded to the dominant spectral features of the major sound-producing taxa on these reefs, fish, and snapping shrimp, respectively. In the low-frequency band, the presence of humpback whales (December-May) was a major contributor to sound level, whereas in the high-frequency band sound level closely tracked water temperature. On shorter timescales, the magnitude of the diel trend in sound production was greater than that of the lunar trend, but both varied in strength among reefs, which may reflect differences in the species assemblages present. Results indicated that the magnitude of the diel trend was related to fish densities at low frequencies and coral cover at high frequencies; however, the strength of these relationships varied by season. Thus, long-term acoustic recordings capture the substantial acoustic variability present in coral-reef ecosystems and provide insight into the presence and relative abundance of sound-producing organisms.

  7. Water column productivity and temperature predict coral reef regeneration across the Indo-Pacific.

    Science.gov (United States)

    Riegl, B; Glynn, P W; Wieters, E; Purkis, S; d'Angelo, C; Wiedenmann, J

    2015-02-05

    Predicted increases in seawater temperatures accelerate coral reef decline due to mortality by heat-driven coral bleaching. Alteration of the natural nutrient environment of reef corals reduces tolerance of corals to heat and light stress and thus will exacerbate impacts of global warming on reefs. Still, many reefs demonstrate remarkable regeneration from past stress events. This paper investigates the effects of sea surface temperature (SST) and water column productivity on recovery of coral reefs. In 71 Indo-Pacific sites, coral cover changes over the past 1-3 decades correlated negative-exponentially with mean SST, chlorophyll a, and SST rise. At six monitoring sites (Persian/Arabian Gulf, Red Sea, northern and southern Galápagos, Easter Island, Panama), over half of all corals were <31 years, implying that measured environmental variables indeed shaped populations and community. An Indo-Pacific-wide model suggests reefs in the northwest and central Indian Ocean, as well as the central west Pacific, are at highest risk of degradation, and those at high latitudes the least. The model pinpoints regions where coral reefs presently have the best chances for survival. However, reefs best buffered against temperature and nutrient effects are those that current studies suggest to be most at peril from future ocean acidification.

  8. Multi-scale ocean and climate drivers of widespread bleaching in the Coral Triangle

    Science.gov (United States)

    Drenkard, E.; Curchitser, E. N.; Kleypas, J. A.; Castruccio, F. S.

    2016-12-01

    The Maritime Continent is home to the Coral Triangle (CT): the global pinnacle of tropical coral biodiversity. Historically, extensive bleaching-induced mortality (caused by thermal stress) among corals in the CT has been associated with extremes in the El Niño Southern Oscillation (ENSO), particularly years when a strong El Niños transitions to a La Niña state (i.e., 1998 and 2010). Similarities in the spatial distribution of satellite-derived indices, and the multi-scale environmental drivers of elevated sea surface temperatures (SSTs) during the 1998 and 2010 bleaching events suggests a potential predictability that has important implications for reef conservation. Using numerical models and ocean and atmosphere reanalysis products, we discuss the roles of ENSO-associated anomalies in both large-scale atmospheric circulation patterns (e.g., South Asian Monsoon) and regional ocean-cooling mechanisms such as coastal upwelling, tropical storm activity, and divergent (i.e., upwelling) circulation patterns (e.g., the Mindanao Eddy) in determining SSTs and, consequently projected patterns of reef ecosystem vulnerability to thermal stress. Conditions associated with the recent and ongoing 2015/2016 coral bleaching and mortality will be compared/contrasted.

  9. Peroxy bleaches

    International Nuclear Information System (INIS)

    Carson, P.A.; Fairclough, C.S.; Mauduit, C.; Colsell, M.

    2006-01-01

    The thermodynamic and kinetic properties of a series of inorganic and organic peroxy bleaches were determined using adiabatic rate calorimetry and isothermal microcalorimetry. Results are compared to calculated oxygen balance values. The decomposition of the majority of the compounds is complex. Data indicate the need for cooling during the storage and transport for some materials evaluated. Although no overall structure/activity relationship could be established because of the diversity of molecular architectures studied, a combination of decomposition and activation energy data provides a means for hazard and risk classification

  10. From Citizen Science to Policy Development on the Coral Reefs of Jamaica

    Directory of Open Access Journals (Sweden)

    M. James C. Crabbe

    2012-01-01

    Full Text Available This paper explores the application of citizen science to help generation of scientific data and capacity-building, and so underpin scientific ideas and policy development in the area of coral reef management, on the coral reefs of Jamaica. From 2000 to 2008, ninety Earthwatch volunteers were trained in coral reef data acquisition and analysis and made over 6,000 measurements on fringing reef sites along the north coast of Jamaica. Their work showed that while recruitment of small corals is returning after the major bleaching event of 2005, larger corals are not necessarily so resilient and so need careful management if the reefs are to survive such major extreme events. These findings were used in the development of an action plan for Jamaican coral reefs, presented to the Jamaican National Environmental Protection Agency. It was agreed that a number of themes and tactics need to be implemented in order to facilitate coral reef conservation in the Caribbean. The use of volunteers and citizen scientists from both developed and developing countries can help in forging links which can assist in data collection and analysis and, ultimately, in ecosystem management and policy development.

  11. Cascading effects of thermally-induced anemone bleaching on associated anemonefish hormonal stress response and reproduction.

    Science.gov (United States)

    Beldade, Ricardo; Blandin, Agathe; O'Donnell, Rory; Mills, Suzanne C

    2017-10-10

    Organisms can behaviorally, physiologically, and morphologically adjust to environmental variation via integrative hormonal mechanisms, ultimately allowing animals to cope with environmental change. The stress response to environmental and social changes commonly promotes survival at the expense of reproduction. However, despite climate change impacts on population declines and diversity loss, few studies have attributed hormonal stress responses, or their regulatory effects, to climate change in the wild. Here, we report hormonal and fitness responses of individual wild fish to a recent large-scale sea warming event that caused widespread bleaching on coral reefs. This 14-month monitoring study shows a strong correlation between anemone bleaching (zooxanthellae loss), anemonefish stress response, and reproductive hormones that decreased fecundity by 73%. These findings suggest that hormone stress responses play a crucial role in changes to population demography following climate change and plasticity in hormonal responsiveness may be a key mechanism enabling individual acclimation to climate change.Elevated temperatures can cause anemones to bleach, with unknown effects on their associated symbiotic fish. Here, Beldade and colleagues show that climate-induced bleaching alters anemonefish hormonal stress response, resulting in decreased reproductive hormones and severely impacted reproduction.

  12. Operationalizing resilience for adaptive coral reef management under global environmental change.

    Science.gov (United States)

    Anthony, Kenneth R N; Marshall, Paul A; Abdulla, Ameer; Beeden, Roger; Bergh, Chris; Black, Ryan; Eakin, C Mark; Game, Edward T; Gooch, Margaret; Graham, Nicholas A J; Green, Alison; Heron, Scott F; van Hooidonk, Ruben; Knowland, Cheryl; Mangubhai, Sangeeta; Marshall, Nadine; Maynard, Jeffrey A; McGinnity, Peter; McLeod, Elizabeth; Mumby, Peter J; Nyström, Magnus; Obura, David; Oliver, Jamie; Possingham, Hugh P; Pressey, Robert L; Rowlands, Gwilym P; Tamelander, Jerker; Wachenfeld, David; Wear, Stephanie

    2015-01-01

    Cumulative pressures from global climate and ocean change combined with multiple regional and local-scale stressors pose fundamental challenges to coral reef managers worldwide. Understanding how cumulative stressors affect coral reef vulnerability is critical for successful reef conservation now and in the future. In this review, we present the case that strategically managing for increased ecological resilience (capacity for stress resistance and recovery) can reduce coral reef vulnerability (risk of net decline) up to a point. Specifically, we propose an operational framework for identifying effective management levers to enhance resilience and support management decisions that reduce reef vulnerability. Building on a system understanding of biological and ecological processes that drive resilience of coral reefs in different environmental and socio-economic settings, we present an Adaptive Resilience-Based management (ARBM) framework and suggest a set of guidelines for how and where resilience can be enhanced via management interventions. We argue that press-type stressors (pollution, sedimentation, overfishing, ocean warming and acidification) are key threats to coral reef resilience by affecting processes underpinning resistance and recovery, while pulse-type (acute) stressors (e.g. storms, bleaching events, crown-of-thorns starfish outbreaks) increase the demand for resilience. We apply the framework to a set of example problems for Caribbean and Indo-Pacific reefs. A combined strategy of active risk reduction and resilience support is needed, informed by key management objectives, knowledge of reef ecosystem processes and consideration of environmental and social drivers. As climate change and ocean acidification erode the resilience and increase the vulnerability of coral reefs globally, successful adaptive management of coral reefs will become increasingly difficult. Given limited resources, on-the-ground solutions are likely to focus increasingly on

  13. Climate, bleaching and connectivity in the Coral Triangle.

    Science.gov (United States)

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

    2016-12-01

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

  14. Community production modulates coral reef pH and the sensitivity of ecosystem calcification to ocean acidification

    Science.gov (United States)

    DeCarlo, Thomas M.; Cohen, Anne L.; Wong, George T. F.; Shiah, Fuh-Kwo; Lentz, Steven J.; Davis, Kristen A.; Shamberger, Kathryn E. F.; Lohmann, Pat

    2017-01-01

    Coral reefs are built of calcium carbonate (CaCO3) produced biogenically by a diversity of calcifying plants, animals, and microbes. As the ocean warms and acidifies, there is mounting concern that declining calcification rates could shift coral reef CaCO3 budgets from net accretion to net dissolution. We quantified net ecosystem calcification (NEC) and production (NEP) on Dongsha Atoll, northern South China Sea, over a 2 week period that included a transient bleaching event. Peak daytime pH on the wide, shallow reef flat during the nonbleaching period was ˜8.5, significantly elevated above that of the surrounding open ocean (˜8.0-8.1) as a consequence of daytime NEP (up to 112 mmol C m-2 h-1). Diurnal-averaged NEC was 390 ± 90 mmol CaCO3 m-2 d-1, higher than any other coral reef studied to date despite comparable calcifier cover (25%) and relatively high fleshy algal cover (19%). Coral bleaching linked to elevated temperatures significantly reduced daytime NEP by 29 mmol C m-2 h-1. pH on the reef flat declined by 0.2 units, causing a 40% reduction in NEC in the absence of pH changes in the surrounding open ocean. Our findings highlight the interactive relationship between carbonate chemistry of coral reef ecosystems and ecosystem production and calcification rates, which are in turn impacted by ocean warming. As open-ocean waters bathing coral reefs warm and acidify over the 21st century, the health and composition of reef benthic communities will play a major role in determining on-reef conditions that will in turn dictate the ecosystem response to climate change.

  15. Patterns in reef fish assemblages: Insights from the Chagos Archipelago.

    Science.gov (United States)

    Samoilys, Melita; Roche, Ronan; Koldewey, Heather; Turner, John

    2018-01-01

    Understanding the drivers of variability in the composition of fish assemblages across the Indo-Pacific region is crucial to support coral reef ecosystem resilience. Whilst numerous relationships and feedback mechanisms between the functional roles of coral reef fishes and reef benthic composition have been investigated, certain key groups, such as the herbivores, are widely suggested to maintain reefs in a coral-dominated state. Examining links between fishes and reef benthos is complicated by the interactions between natural processes, disturbance events and anthropogenic impacts, particularly fishing pressure. This study examined fish assemblages and associated benthic variables across five atolls within the Chagos Archipelago, where fishing pressure is largely absent, to better understand these relationships. We found high variability in fish assemblages among atolls and sites across the archipelago, especially for key groups such as a suite of grazer-detritivore surgeonfish, and the parrotfishes which varied in density over 40-fold between sites. Differences in fish assemblages were significantly associated with variable levels of both live and recently dead coral cover and rugosity. We suggest these results reflect differing coral recovery trajectories following coral bleaching events and a strong influence of 'bottom-up' control mechanisms on fish assemblages. Species level analyses revealed that Scarus niger, Acanthurus nigrofuscus and Chlorurus strongylocephalos were key species driving differences in fish assemblage structure. Clarifying the trophic roles of herbivorous and detritivorous reef fishes will require species-level studies, which also examine feeding behaviour, to fully understand their contribution in maintaining reef resilience to climate change and fishing impacts.

  16. Patterns in reef fish assemblages: Insights from the Chagos Archipelago

    Science.gov (United States)

    Roche, Ronan; Koldewey, Heather; Turner, John

    2018-01-01

    Understanding the drivers of variability in the composition of fish assemblages across the Indo-Pacific region is crucial to support coral reef ecosystem resilience. Whilst numerous relationships and feedback mechanisms between the functional roles of coral reef fishes and reef benthic composition have been investigated, certain key groups, such as the herbivores, are widely suggested to maintain reefs in a coral-dominated state. Examining links between fishes and reef benthos is complicated by the interactions between natural processes, disturbance events and anthropogenic impacts, particularly fishing pressure. This study examined fish assemblages and associated benthic variables across five atolls within the Chagos Archipelago, where fishing pressure is largely absent, to better understand these relationships. We found high variability in fish assemblages among atolls and sites across the archipelago, especially for key groups such as a suite of grazer-detritivore surgeonfish, and the parrotfishes which varied in density over 40-fold between sites. Differences in fish assemblages were significantly associated with variable levels of both live and recently dead coral cover and rugosity. We suggest these results reflect differing coral recovery trajectories following coral bleaching events and a strong influence of ‘bottom-up’ control mechanisms on fish assemblages. Species level analyses revealed that Scarus niger, Acanthurus nigrofuscus and Chlorurus strongylocephalos were key species driving differences in fish assemblage structure. Clarifying the trophic roles of herbivorous and detritivorous reef fishes will require species-level studies, which also examine feeding behaviour, to fully understand their contribution in maintaining reef resilience to climate change and fishing impacts. PMID:29351566

  17. Differential responses of emergent intertidal coral reef fauna to a large-scale El-Niño southern oscillation event: sponge and coral resilience.

    Science.gov (United States)

    Kelmo, Francisco; Bell, James J; Moraes, Simone Souza; Gomes, Rilza da Costa Tourinho; Mariano-Neto, Eduardo; Attrill, Martin J

    2014-01-01

    There is a paucity of information on the impacts of the 1997-8 El Niño event and subsequent climatic episodes on emergent intertidal coral reef assemblages. Given the environmental variability intertidal reefs experience, such reefs may potentially be more resilient to climatic events and provide important insights into the adaptation of reef fauna to future ocean warming. Here we report the results of a 17-year (1995-2011) biodiversity survey of four emergent coral reef ecosystems in Bahia, Brazil, to assess the impact of a major El Niño event on the reef fauna, and determine any subsequent recovery. The densities of two species of coral, Favia gravida and Siderastrea stellata, did not vary significantly across the survey period, indicating a high degree of tolerance to the El Niño associated stress. However, there were marked decreases in the diversity of other taxa. Molluscs, bryozoans and ascidians suffered severe declines in diversity and abundance and had not recovered to pre-El Niño levels by the end of the study. Echinoderms were reduced to a single species in 1999, Echinometra lucunter, although diversity levels had recovered by 2002. Sponge assemblages were not impacted by the 1997-8 event and their densities had increased by the study end. Multivariate analysis indicated that a stable invertebrate community had re-established on the reefs after the El Niño event, but it has a different overall composition to the pre-El Niño community. It is unclear if community recovery will continue given more time, but our study highlights that any increase in the frequency of large-scale climatic events to more than one a decade is likely to result in a persistent lower-diversity state. Our results also suggest some coral and sponge species are particularly resilient to the El Niño-associated stress and therefore represent suitable models to investigate temperature adaptation in reef organisms.

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

    Science.gov (United States)

    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...

  19. Unique Sequence of Events Triggers Manta Ray Feeding Frenzy in the Southern Great Barrier Reef, Australia

    Directory of Open Access Journals (Sweden)

    Scarla J. Weeks

    2015-03-01

    Full Text Available Manta rays are classified as Vulnerable to Extinction on the IUCN Red List for Threatened Species. In Australia, a key aggregation site for reef manta rays is Lady Elliot Island (LEI on the Great Barrier Reef, ~7 km from the shelf edge. Here, we investigate the environmental processes that triggered the largest manta ray feeding aggregation yet observed in Australia, in early 2013. We use MODIS sea surface temperature (SST, chlorophyll-a concentration and photic depth data, together with in situ data, to show that anomalous river discharges led to high chlorophyll (anomalies: 10–15 mg∙m−3 and turbid (photic depth anomalies: −15 m river plumes extending out to LEI, and that these became entrained offshore around the periphery of an active cyclonic eddy. Eddy dynamics led to cold bottom intrusions along the shelf edge (6 °C temperature decrease, and at LEI (5 °C temperature decrease. Strongest SST gradients (>1 °C∙km−1 were at the convergent frontal zone between the shelf and eddy-influenced waters, directly overlying LEI. Here, the front intensified on the spring ebb tide to attract and shape the aggregation pattern of foraging manta rays. Future research could focus on mapping the probability and persistence of these ecologically significant frontal zones via remote sensing to aid the management and conservation of marine species.

  20. Coral bleaching at Little Cayman, Cayman Islands 2009

    Science.gov (United States)

    van Hooidonk, Ruben J.; Manzello, Derek P.; Moye, Jessica; Brandt, Marilyn E.; Hendee, James C.; McCoy, Croy; Manfrino, Carrie

    2012-06-01

    The global rise in sea temperature through anthropogenic climate change is affecting coral reef ecosystems through a phenomenon known as coral bleaching; that is, the whitening of corals due to the loss of the symbiotic zooxanthellae which impart corals with their characteristic vivid coloration. We describe aspects of the most prevalent episode of coral bleaching ever recorded at Little Cayman, Cayman Islands, during the fall of 2009. The most susceptible corals were found to be, in order, Siderastrea siderea, Montastraea annularis, and Montastraea faveolata, while Diplora strigosa and Agaricia spp. were less so, yet still showed considerable bleaching prevalence and severity. Those found to be least susceptible were Porites porites, Porites astreoides, and Montastraea cavernosa. These observations and other reported observations of coral bleaching, together with 29 years (1982-2010) of satellite-derived sea surface temperatures, were used to optimize bleaching predictions at this location. To do this a Degree Heating Weeks (DHW) and Peirce Skill Score (PSS) analysis was employed to calculate a local bleaching threshold above which bleaching was expected to occur. A threshold of 4.2 DHW had the highest skill, with a PSS of 0.70. The method outlined here could be applied to other regions to find the optimal bleaching threshold and improve bleaching predictions.

  1. Global warming transforms coral reef assemblages.

    Science.gov (United States)

    Hughes, Terry P; Kerry, James T; Baird, Andrew H; Connolly, Sean R; Dietzel, Andreas; Eakin, C Mark; Heron, Scott F; Hoey, Andrew S; Hoogenboom, Mia O; Liu, Gang; McWilliam, Michael J; Pears, Rachel J; Pratchett, Morgan S; Skirving, William J; Stella, Jessica S; Torda, Gergely

    2018-04-01

    Global warming is rapidly emerging as a universal threat to ecological integrity and function, highlighting the urgent need for a better understanding of the impact of heat exposure on the resilience of ecosystems and the people who depend on them 1 . Here we show that in the aftermath of the record-breaking marine heatwave on the Great Barrier Reef in 2016 2 , corals began to die immediately on reefs where the accumulated heat exposure exceeded a critical threshold of degree heating weeks, which was 3-4 °C-weeks. After eight months, an exposure of 6 °C-weeks or more drove an unprecedented, regional-scale shift in the composition of coral assemblages, reflecting markedly divergent responses to heat stress by different taxa. Fast-growing staghorn and tabular corals suffered a catastrophic die-off, transforming the three-dimensionality and ecological functioning of 29% of the 3,863 reefs comprising the world's largest coral reef system. Our study bridges the gap between the theory and practice of assessing the risk of ecosystem collapse, under the emerging framework for the International Union for Conservation of Nature (IUCN) Red List of Ecosystems 3 , by rigorously defining both the initial and collapsed states, identifying the major driver of change, and establishing quantitative collapse thresholds. The increasing prevalence of post-bleaching mass mortality of corals represents a radical shift in the disturbance regimes of tropical reefs, both adding to and far exceeding the influence of recurrent cyclones and other local pulse events, presenting a fundamental challenge to the long-term future of these iconic ecosystems.

  2. African dust and the demise of Caribbean coral reefs

    Science.gov (United States)

    Shinn, E.A.; Smith, G.W.; Prospero, J.M.; Betzer, P.; Hayes, M.L.; Garrison, V.; Barber, R.T.

    2000-01-01

    The vitality of Caribbean coral reefs has undergone a continual state of decline since the late 1970s, a period of time coincidental with large increases in transatlantic dust transport. It is proposed that the hundreds of millions of tons/year of soil dust that have been crossing the Atlantic during the last 25 years could be a significant contributor to coral reef decline and may be affecting other ecosystems. Benchmark events, such as near synchronous Caribbean-wide mortalities of acroporid corals and the urchin Diadema in 1983, and coral bleaching beginning in 1987, correlate with the years of maximum dust flux into the Caribbean. Besides crustal elements, in particular Fe, Si, and aluminosilicate clays, the dust can serve as a substrate for numerous species of viable spores, especially the soil fungus Aspergillus. Aspergillus sydowii, the cause of an ongoing Caribbean-wide seafan disease, has been cultured from Caribbean air samples and used to inoculate sea fans.

  3. Unmixing-Based Denoising as a Pre-Processing Step for Coral Reef Analysis

    Science.gov (United States)

    Cerra, D.; Traganos, D.; Gege, P.; Reinartz, P.

    2017-05-01

    Coral reefs, among the world's most biodiverse and productive submerged habitats, have faced several mass bleaching events due to climate change during the past 35 years. In the course of this century, global warming and ocean acidification are expected to cause corals to become increasingly rare on reef systems. This will result in a sharp decrease in the biodiversity of reef communities and carbonate reef structures. Coral reefs may be mapped, characterized and monitored through remote sensing. Hyperspectral images in particular excel in being used in coral monitoring, being characterized by very rich spectral information, which results in a strong discrimination power to characterize a target of interest, and separate healthy corals from bleached ones. Being submerged habitats, coral reef systems are difficult to analyse in airborne or satellite images, as relevant information is conveyed in bands in the blue range which exhibit lower signal-to-noise ratio (SNR) with respect to other spectral ranges; furthermore, water is absorbing most of the incident solar radiation, further decreasing the SNR. Derivative features, which are important in coral analysis, result greatly affected by the resulting noise present in relevant spectral bands, justifying the need of new denoising techniques able to keep local spatial and spectral features. In this paper, Unmixing-based Denoising (UBD) is used to enable analysis of a hyperspectral image acquired over a coral reef system in the Red Sea based on derivative features. UBD reconstructs pixelwise a dataset with reduced noise effects, by forcing each spectrum to a linear combination of other reference spectra, exploiting the high dimensionality of hyperspectral datasets. Results show clear enhancements with respect to traditional denoising methods based on spatial and spectral smoothing, facilitating the coral detection task.

  4. Tradeoffs to Thermal Acclimation: Energetics and Reproduction of a Reef Coral with Heat Tolerant Symbiodinium Type-D

    Directory of Open Access Journals (Sweden)

    Alison M. Jones

    2011-01-01

    Full Text Available The photo-physiological characteristics of thermo-tolerant Symbiodinium types have been postulated to have negative effects on the energetics of the reef corals by reducing fitness. To investigate this, two key and inextricably coupled indicators of fitness, lipids and reproduction, were monitored in colonies of the broadcast-spawning coral Acropora millepora over a two-year period that included a natural bleaching event. In the absence of bleaching ITS1-type clade D predominant colonies had 26% lower stored lipids compared to C2 colonies. At spawning time, this correlated with 28% smaller eggs in type-D colonies. This energetic disparity is expected to have reduced larval duration and settlement-competency periods in type-D compared to type-C2 colonies. More importantly, irrespective of the effect of genotype, the fitness of all corals was adversely affected by the stress of the bleaching event which reduced prespawning lipids by 60% and halved the number of eggs compared to the previous year. Our results extend work that has shown that direct temperature stress and symbiont change are likely to work in concert on corals by demonstrating that the lipids and reproduction of the reef building corals on tropical reefs are likely to be impaired by these processes as our climate warms.

  5. Changes in coral reef metabolism during the 2015 El Niño in the eastern Pacific

    Science.gov (United States)

    McGillis, W. R.; Manzello, D.; Smith, T. B.; Baker, A.; Fong, P.; Glynn, P.; Smith, J.; Takeshita, Y.; Martz, T. R.; Hsueh, D.; Langdon, C.; Price, N.; Mate, J.

    2016-02-01

    The likely strong 2015-2016 El Niño event offers an opportunity to assess coral reef benthic metabolism under stressful high temperatures, coral bleaching, and mortality. During a period of increasing ocean temperatures caused by the 2015-2016 El Niño-Southern Oscillation (ENSO), we assessed the metabolism, at hourly intervals, of eastern Pacific coral reefs using the Benthic Ecosystem and Acidification Measurement System (BEAMS). We measured coral reef net ecosystem productivity (NEP) and net ecosystem calcification (NEC) in 2014 before the start of the El Niño event and in 2015 during the first anomalously high sea surface temperatures of the 2015 El Niño. Increases in ocean temperatures of 1-2°C between 2014 and 2015 caused over 30% decline in calcification at Uva Is. (Panama) and Darwin Is. (Galapagos), along with significant coral bleaching at Uva and coral paling at Darwin. Warming at Saboga Island, in the seasonally upwelling Gulf of Panama, was only 0.3oC, did not result in significant bleaching, and was accompanied by a significant increase in coral reef metabolism. Additional key findings include an increase in nighttime dissolution of calcium carbonate during ENSO heating. Light-NEP and light-NEC relationships were generated for each location, and showed that variations in metabolism were strongly correlated with the incident bottom solar intensity, with strong daily cycles and patterns of light-enhanced calcification also identified. The response of different coral species also provides in situ data on the varying metabolism. The metabolism of the 2015-2016 El Niño shows the possible reef function under future warming and acidified conditions. These emerging results may be harbingers of significant further decreases in metabolism, and other detrimental impacts, if this region experiences additional warming during the current ENSO event.

  6. Coral reef health response to chronic and acute changes in water quality in St. Thomas, United States Virgin Islands.

    Science.gov (United States)

    Ennis, Rosmin S; Brandt, Marilyn E; Wilson Grimes, Kristin R; Smith, Tyler B

    2016-10-15

    It is suspected that land cover alteration on the southern coast of St. Thomas, USVI has increased runoff, degrading nearshore water quality and coral reef health. Chronic and acute changes in water quality, sediment deposition, and coral health metrics were assessed in three zones based upon perceived degree of human influence. Chlorophyll (pturbidity (p=0.0113) were significantly higher in nearshore zones and in the high impact zone during heavy precipitation. Net sediment deposition and terrigenous content increased in nearshore zones during periods of greater precipitation and port activity. Macroalgae overgrowth significantly increased along a gradient of decreasing water quality (p<0.0001). Coral bleaching in all zones peaked in November with a regional thermal stress event (p<0.0001). However, mean bleaching prevalence was significantly greater in the most impacted zone compared to the offshore zone (p=0.0396), suggesting a link between declining water quality and bleaching severity. Published by Elsevier Ltd.

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

    Science.gov (United States)

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

    2013-09-30

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  10. Global change and modern coral reefs: New opportunities to understand shallow-water carbonate depositional processes

    Science.gov (United States)

    Hallock, Pamela

    2005-04-01

    Human activities are impacting coral reefs physically, biologically, and chemically. Nutrification, sedimentation, chemical pollution, and overfishing are significant local threats that are occurring worldwide. Ozone depletion and global warming are triggering mass coral-bleaching events; corals under temperature stress lose the ability to synthesize protective sunscreens and become more sensitive to sunlight. Photo-oxidative stress also reduces fitness, rendering reef-building organisms more susceptible to emerging diseases. Increasing concentration of atmospheric CO 2 has already reduced CaCO 3 saturation in surface waters by more than 10%. Doubling of atmospheric CO 2 concentration over pre-industrial concentration in the 21st century may reduce carbonate production in tropical shallow marine environments by as much as 80%. As shallow-water reefs decline worldwide, opportunities abound for researchers to expand understanding of carbonate depositional systems. Coordinated studies of carbonate geochemistry with photozoan physiology and calcification, particularly in cool subtropical-transition zones between photozoan-reef and heterotrophic carbonate-ramp communities, will contribute to understanding of carbonate sedimentation under environmental change, both in the future and in the geologic record. Cyanobacteria are becoming increasingly prominent on declining reefs, as these microbes can tolerate strong solar radiation, higher temperatures, and abundant nutrients. The responses of reef-dwelling cyanobacteria to environmental parameters associated with global change are prime topics for further research, with both ecological and geological implications.

  11. Benthic Images from Towed-Diver Surveys in the Main Hawaiian Islands to Assess the Mass Coral Bleaching Event in November 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A team from the Pacific Islands Fisheries Science Center (PIFSC), Coral Reef Ecosystem Program (CREP) deployed on a two-week research cruise in November 2015 to...

  12. The northernmost coral frontier of the Maldives: The coral reefs of Ihavandippolu Atoll under long-term environmental change.

    Science.gov (United States)

    Tkachenko, Konstantin S

    2012-12-01

    Ihavandippolu, the northernmost atoll of the Maldives, experienced severe coral bleaching and mortality in 1998 followed by several bleaching episodes in the last decade. Coral 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 coral 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 coral cover (>40%) with a dominance of branching Acropora that is known to be one of the coral genera that is most susceptible to thermal stress. The last severe bleaching event in 2010 resulted in high coral mortality in some sites of the atoll. Differences in coral 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 coral overgrowth by macroalgae even on degraded reefs. Despite the frequent influence of temperature anomalies and having less geomorphologic refuges for coral survivals than other larger Maldivian atolls, a major part of observed coral communities in Ihavandippolu Atoll exhibits high resilience and potential for further acclimatization to a changing environment. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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. Copyright © 2016. Published by Elsevier B.V.

  14. The Stability of the Giant Clam Holobiont over Time and during Bleaching Stress

    KAUST Repository

    Pappas, Melissa

    2017-01-01

    Experimental bleaching shows that Red Sea giant clams, although exposed to rather hot temperatures naturally, will bleach at 34°C after two weeks, and severely bleached clams likely will not recover. During bleaching, Symbiodinium types shift as well, and shift more drastically than seasonal shifts during the year. This shifting may be an evolved characteristic of the giant clam to aid in surviving major changes in the environment. However, more research is needed to determine if these holobionts are capable of keeping up with the global forecast of warming in reef environments.

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

    KAUST Repository

    Hadaidi, Ghaida Ali Hassan; Rö thig, Till; Yum, Lauren; 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

  16. Bleaching Dengan Teknologi Laser

    OpenAIRE

    Eliwaty

    2008-01-01

    Penulisan tentang bleaching dengan laser dimaksudkan untuk menambah wawasan serta pengetahuan dari pembaca di bidang kedokteran gigi. Macam-macam laser yang dipergunakan dalam bleaching yaitu argon, CO2 serta dioda laser. Contoh merek produk laser yaitu Blulaze, Dentcure untuk argonlaser, Novapulse untuk C02 serta Opus 5 untuk dioda laser. Laser bleaching hasilnya dapat dicapai dalam satu kunjungan saja, cepat, efisien namun biayanya relatif mahal, dapat menimbulkan burn, sensitivitas se...

  17. A diverse assemblage of reef corals thriving in a dynamic intertidal reef setting (Bonaparte Archipelago, Kimberley, Australia.

    Directory of Open Access Journals (Sweden)

    Zoe T Richards

    Full Text Available The susceptibility of reef-building corals to climatic anomalies is well documented and a cause of great concern for the future of coral reefs. Reef corals are normally considered to tolerate only a narrow range of climatic conditions with only a small number of species considered heat-tolerant. Occasionally however, corals can be seen thriving in unusually harsh reef settings and these are cause for some optimism about the future of coral reefs. Here we document for the first time a diverse assemblage of 225 species of hard corals occurring in the intertidal zone of the Bonaparte Archipelago, north western Australia. We compare the environmental conditions at our study site (tidal regime, SST and level of turbidity with those experienced at four other more typical tropical reef locations with similar levels of diversity. Physical extremes in the Bonaparte Archipelago include tidal oscillations of up to 8 m, long subaerial exposure times (>3.5 hrs, prolonged exposure to high SST and fluctuating turbidity levels. We conclude the timing of low tide in the coolest parts of the day ameliorates the severity of subaerial exposure, and the combination of strong currents and a naturally high sediment regime helps to offset light and heat stress. The low level of anthropogenic impact and proximity to the Indo-west Pacific centre of diversity are likely to further promote resistance and resilience in this community. This assemblage provides an indication of what corals may have existed in other nearshore locations in the past prior to widespread coastal development, eutrophication, coral predator and disease outbreaks and coral bleaching events. Our results call for a re-evaluation of what conditions are optimal for coral survival, and the Bonaparte intertidal community presents an ideal model system for exploring how species resilience is conferred in the absence of confounding factors such as pollution.

  18. Changes in coral reef communities among the Florida Keys, 1996-2003

    Science.gov (United States)

    Somerfield, P. J.; Jaap, W. C.; Clarke, K. R.; Callahan, M.; Hackett, K.; Porter, J.; Lybolt, M.; Tsokos, C.; Yanev, G.

    2008-12-01

    Hard coral (Scleractinia and Milleporina) cover data were examined from 37 sites surveyed annually from 1996 to 2003 in the Florida reef tract, USA. Analyses of species numbers and total cover showed that site-to-site differences were generally very much greater than differences among times within sites. There were no significant differences among different geographical areas within the reef tract (Upper, Middle and Lower Keys). Large-scale changes documented included a reduction in species numbers and total cover on both deep and shallow offshore reefs between 1997 and 1999 followed by no recovery in cover, and only scant evidence of any recovery in species numbers by 2003. These changes coincided with bleaching events in 1997 and 1998, and the passage of Hurricane Georges through the Lower Keys in 1998. The lack of recovery among offshore reefs suggests that they were no longer resilient. Multivariate analyses revealed that some sites showed relatively little temporal variation in community composition, essentially random in direction, while others showed relatively large year-on-year changes. There was little evidence of any major region-wide changes affecting assemblage composition, or of any events that had impacted all of the sampling sites in any single year. Instead, different sites exhibited differing patterns of temporal variation, with certain sites displaying greater variation than others. Changes in community composition at some sites are interpreted in the light of knowledge of events at those sites and the relative sensitivities of species to various stressors, such as changes in cover of Acropora palmata and Millepora complanata at Sand Key following the bleaching events and hurricane in 1998, and declines in Montastraea annularis at Smith Shoal following a harmful algal bloom in 2002. For most sites, however, it is impossible to determine the causes of observed variation.

  19. Long-term growth rates and effects of bleaching in Acropora hyacinthus

    Science.gov (United States)

    Gold, Zachary; Palumbi, Stephen R.

    2018-03-01

    Understanding the response of coral growth to natural variation in the environment, as well as to acute temperature stress under current and future climate change conditions, is critical to predicting the future health of coral reef ecosystems. As such, ecological surveys are beginning to focus on corals that live in high thermal stress environments to understand how future coral populations may adapt to climate change. We investigated the relationship between coral growth, thermal microhabitat, symbionts type, and thermal acclimatization of four species of the Acropora hyacinthus complex in back-reef lagoons in American Samoa. Coral growth was measured from August 2010 to April 2016 using horizontal planar area of coral colonies derived from photographs and in situ maximum width measurements. Despite marked intraspecific variation, we found that planar colony growth rates were significantly different among cryptic species. The highly heat tolerant A. hyacinthus variant "HE" increased in area an average of 2.9% month-1 (0.03 cm average mean radial extension month-1). By contrast, the three less tolerant species averaged 6.1% (0.07 cm average mean radial extension month-1). Planar growth rates were 40% higher on average in corals harboring Clade C versus Clade D symbiont types, although marked inter-colony variation in growth rendered this difference nonsignificant. Planar growth rates for all four species dropped to near zero following a 2015 bleaching event, independent of the visually estimated percent area of bleaching. Within 1 yr, growth rates recovered to previous levels, confirming previous studies that found sublethal effects of thermal stress on coral growth. Long-term studies of individual coral colonies provide an important tool to measure impacts of environmental change and allow integration of coral physiology, genetics, symbionts, and microclimate on reef growth patterns.

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

    Science.gov (United States)

    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.

  1. Satellite-Observed Black Water Events off Southwest Florida: Implications for Coral Reef Health in the Florida Keys National Marine Sanctuary

    Directory of Open Access Journals (Sweden)

    Brian Lapointe

    2013-01-01

    Full Text Available A “black water” event, as observed from satellites, occurred off southwest Florida in 2012. Satellite observations suggested that the event started in early January and ended in mid-April 2012. The black water patch formed off central west Florida and advected southward towards Florida Bay and the Florida Keys with the shelf circulation, which was confirmed by satellite-tracked surface drifter trajectories. Compared with a previous black water event in 2002, the 2012 event was weaker in terms of spatial and temporal coverage. An in situ survey indicated that the 2012 black water patch contained toxic K. brevis and had relatively low CDOM (colored dissolved organic matter and turbidity but high chlorophyll-a concentrations, while salinity was somewhat high compared with historical values. Further analysis revealed that the 2012 black water was formed by the K. brevis bloom initiated off central west Florida in late September 2011, while river runoff, Trichodesmium and possibly submarine groundwater discharge also played important roles in its formation. Black water patches can affect benthic coral reef communities by decreasing light availability at the bottom, and enhanced nutrient concentrations from black water patches support massive macroalgae growth that can overgrow coral reefs. It is thus important to continue the integrated observations where satellites provide synoptic and repeated observations of such adverse water quality events.

  2. Opalescence of bleached teeth.

    Science.gov (United States)

    Schmeling, Max; Maia, Hamilton Pires; Baratieri, Luiz Narciso

    2012-07-01

    To evaluate the influence of tooth bleaching on the opalescence properties of enamel. Color of 38 specimens was determined by colorimetric analysis before and after bleaching in the reflectance and transmittance modes. The results were described as CIELab color coordinates. The Opalescent Parameter (OP) was calculated as the difference in yellow-blue color coordinate (CIE Δb*) and red-green color coordinate (CIE Δa*) between the reflected and transmitted colors. Mean OP value of the specimens was 18.9 (±1.6) before bleaching and 16.1 (±1.0) after bleaching. Bleaching decreases the OP of the specimens (p>0.001). OP decrease was correlated with differences in b* color coordinate in the transmittance mode. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Variability in the phytoplankton community of Kavaratti reef ecosystem (northern Indian Ocean) during peak and waning periods of El Niño 2016.

    Science.gov (United States)

    Karati, Kusum Komal; Vineetha, G; Madhu, N V; Anil, P; Dayana, M; Shihab, B K; Muhsin, A I; Riyas, C; Raveendran, T V

    2017-11-29

    El Niño, an interannual climate event characterized by elevated oceanic temperature, is a prime threat for coral reef ecosystems worldwide, owing to their thermal threshold sensitivity. Phytoplankton plays a crucial role in the sustenance of reef trophodynamics. The cell size of the phytoplankton forms the "master morphological trait" with implications for growth, resource acquisition, and adaptability to nutrients. In the context of a strong El Niño prediction for 2015-2016, the present study was undertaken to evaluate the variations in the size-structured phytoplankton of Kavaratti reef waters, a major coral atoll along the southeast coast of India. The present study witnessed a remarkable change in the physicochemical environment of the reef water and massive coral bleaching with the progression of El Niño 2015-2016 from its peak to waning phase. The fluctuations observed in sea surface temperature, pH, and nutrient concentration of the reef water with the El Niño progression resulted in a remarkable shift in phytoplankton size structure, abundance, and community composition of the reef waters. Though low nutrient concentration of the waning phase resulted in lower phytoplankton biomass and abundance, the diazotroph Trichodesmium erythraeum predominated the reef waters, owing to its capability of the atmospheric nitrogen fixation and dissolved organic phosphate utilization.

  4. The engine of the reef: Photobiology of the coral-algal symbiosis

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    Melissa Susan Roth

    2014-08-01

    Full Text Available Coral reef ecosystems thrive in tropical oligotrophic oceans because of the relationship between corals and endosymbiotic dinoflagellate algae called Symbiodinium. Symbiodinium convert sunlight and carbon dioxide into organic carbon and oxygen to fuel coral growth and calcification, creating habitat for these diverse and productive ecosystems. Light is thus a key regulating factor shaping the productivity, physiology and ecology of the coral holobiont. Similar to all oxygenic photoautotrophs, Symbiodinium must safely harvest sunlight for photosynthesis and dissipate excess energy to prevent oxidative stress. Oxidative stress is caused by environmental stressors such as those associated with global climate change, and ultimately leads to breakdown of the coral-algal symbiosis known as coral bleaching. Recently, large-scale coral bleaching events have become pervasive and frequent threatening and endangering coral reefs. Because the coral-algal symbiosis is the biological engine producing the reef, the future of coral reef ecosystems depends on the ecophysiology of the symbiosis. This review examines the photobiology of the coral-algal symbiosis with particular focus on the photophysiological responses and timescales of corals and Symbiodinium. Additionally, this review summarizes the light environment and its dynamics, the vulnerability of the symbiosis to oxidative stress, the abiotic and biotic factors influencing photosynthesis, the diversity of the coral-algal symbiosis and recent advances in the field. Studies integrating physiology with the developing omics fields will provide new insights into the coral-algal symbiosis. Greater physiological and ecological understanding of the coral-algal symbiosis is needed for protection and conservation of coral reefs.

  5. The engine of the reef: photobiology of the coral–algal symbiosis

    Science.gov (United States)

    Roth, Melissa S.

    2014-01-01

    Coral reef ecosystems thrive in tropical oligotrophic oceans because of the relationship between corals and endosymbiotic dinoflagellate algae called Symbiodinium. Symbiodinium convert sunlight and carbon dioxide into organic carbon and oxygen to fuel coral growth and calcification, creating habitat for these diverse and productive ecosystems. Light is thus a key regulating factor shaping the productivity, physiology, and ecology of the coral holobiont. Similar to all oxygenic photoautotrophs, Symbiodinium must safely harvest sunlight for photosynthesis and dissipate excess energy to prevent oxidative stress. Oxidative stress is caused by environmental stressors such as those associated with global climate change, and ultimately leads to breakdown of the coral–algal symbiosis known as coral bleaching. Recently, large-scale coral bleaching events have become pervasive and frequent threatening and endangering coral reefs. Because the coral–algal symbiosis is the biological engine producing the reef, the future of coral reef ecosystems depends on the ecophysiology of the symbiosis. This review examines the photobiology of the coral–algal symbiosis with particular focus on the photophysiological responses and timescales of corals and Symbiodinium. Additionally, this review summarizes the light environment and its dynamics, the vulnerability of the symbiosis to oxidative stress, the abiotic and biotic factors influencing photosynthesis, the diversity of the coral–algal symbiosis, and recent advances in the field. Studies integrating physiology with the developing “omics” fields will provide new insights into the coral–algal symbiosis. Greater physiological and ecological understanding of the coral–algal symbiosis is needed for protection and conservation of coral reefs. PMID:25202301

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

    Science.gov (United States)

    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

    2009-08-04

    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. In our experimental procedure, one set of Pocillopora damicornis nubbins was subjected to a gradual increase of water temperature from 28 degrees C to 32 degrees C over 15 days. A second control set kept at constant temperature (28 degrees 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. Under thermal stress

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

    Directory of Open Access Journals (Sweden)

    Tambutte Sylvie

    2009-08-01

    Full Text Available Abstract 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

  8. Does herbivorous fish protection really improve coral reef resilience? A case study from new caledonia (South Pacific).

    Science.gov (United States)

    Carassou, Laure; Léopold, Marc; Guillemot, Nicolas; Wantiez, Laurent; Kulbicki, Michel

    2013-01-01

    Parts of coral reefs from New Caledonia (South Pacific) were registered at the UNESCO World Heritage list in 2008. Management strategies aiming at preserving the exceptional ecological value of these reefs in the context of climate change are currently being considered. This study evaluates the appropriateness of an exclusive fishing ban of herbivorous fish as a strategy to enhance coral reef resilience to hurricanes and bleaching in the UNESCO-registered areas of New Caledonia. A two-phase approach was developed: 1) coral, macroalgal, and herbivorous fish communities were examined in four biotopes from 14 reefs submitted to different fishing pressures in New Caledonia, and 2) results from these analyses were challenged in the context of a global synthesis of the relationship between herbivorous fish protection, coral recovery and relative macroalgal development after hurricanes and bleaching. Analyses of New Caledonia data indicated that 1) current fishing pressure only slightly affected herbivorous fish communities in the country, and 2) coral and macroalgal covers remained unrelated, and macroalgal cover was not related to the biomass, density or diversity of macroalgae feeders, whatever the biotope or level of fishing pressure considered. At a global scale, we found no relationship between reef protection status, coral recovery and relative macroalgal development after major climatic events. These results suggest that an exclusive protection of herbivorous fish in New Caledonia is unlikely to improve coral reef resilience to large-scale climatic disturbances, especially in the lightly fished UNESCO-registered areas. More efforts towards the survey and regulation of major chronic stress factors such as mining are rather recommended. In the most heavily fished areas of the country, carnivorous fish and large targeted herbivores may however be monitored as part of a precautionary approach.

  9. Performance Evaluation of CRW Reef-Scale and Broad-Scale SST-Based Coral Monitoring Products in Fringing Reef Systems of Tobago

    Directory of Open Access Journals (Sweden)

    Shaazia S. Mohammed

    2015-12-01

    Full Text Available Satellite-derived sea surface temperature (SST is used to monitor coral bleaching through the National Oceanic and Atmospheric Administration’s Coral Reef Watch (CRW Decision Support System (DSS. Since 2000, a broad-scale 50 km SST was used to monitor thermal stress for coral reefs globally. However, some discrepancies were noted when applied to small-scale fringing coral reefs. To address this, CRW created a new DSS, specifically targeted at or near reef scales. Here, we evaluated the new reef-scale (5 km resolution products using in situ temperature data and coral bleaching surveys which were also compared with the heritage broad-scale (50 km for three reefs (Buccoo Reef, Culloden and Speyside of the southern Caribbean island of Tobago. Seasonal and annual biases indicated the new 5 km SST generally represents the conditions at these reefs more accurately and more consistently than the 50 km SST. Consistency between satellite and in situ temperature data influences the performance of anomaly-based predictions of bleaching: the 5 km DHW product showed better consistency with bleaching observations than the 50 km product. These results are the first to demonstrate the improvement of the 5 km products over the 50 km predecessors and support their use in monitoring thermal stress of reefs in the southern Caribbean.

  10. Interspecific Hybridization May Provide Novel Opportunities for Coral Reef Restoration

    Directory of Open Access Journals (Sweden)

    Wing Yan Chan

    2018-05-01

    Full Text Available Climate change and other anthropogenic disturbances have created an era characterized by the inability of most ecosystems to maintain their original, pristine states, the Anthropocene. Investigating new and innovative strategies that may facilitate ecosystem restoration is thus becoming increasingly important, particularly for coral reefs around the globe which are deteriorating at an alarming rate. The Great Barrier Reef (GBR lost half its coral cover between 1985 and 2012, and experienced back-to-back heat-induced mass bleaching events and high coral mortality in 2016 and 2017. Here we investigate the efficacy of interspecific hybridization as a tool to develop coral stock with enhanced climate resilience. We crossed two Acropora species pairs from the GBR and examined several phenotypic traits over 28 weeks of exposure to ambient and elevated temperature and pCO2. While elevated temperature and pCO2 conditions negatively affected size and survival of both purebreds and hybrids, higher survival and larger recruit size were observed in some of the hybrid offspring groups under both ambient and elevated conditions. Further, interspecific hybrids had high fertilization rates, normal embryonic development, and similar Symbiodinium uptake and photochemical efficiency as purebred offspring. While the fitness of these hybrids in the field and their reproductive and backcrossing potential remain to be investigated, current findings provide proof-of-concept that interspecific hybridization may produce genotypes with enhanced climate resilience, and has the potential to increase the success of coral reef restoration initiatives.

  11. Potential costs of acclimatization to a warmer climate: growth of a reef coral with heat tolerant vs. sensitive symbiont types.

    Directory of Open Access Journals (Sweden)

    Alison Jones

    Full Text Available One of the principle ways in which reef building corals are likely to cope with a warmer climate is by changing to more thermally tolerant endosymbiotic algae (zooxanthellae genotypes. It is highly likely that hosting a more heat-tolerant algal genotype will be accompanied by tradeoffs in the physiology of the coral. To better understand one of these tradeoffs, growth was investigated in the Indo-Pacific reef-building coral Acropora millepora in both the laboratory and the field. In the Keppel Islands in the southern Great Barrier Reef this species naturally harbors nrDNA ITS1 thermally sensitive type C2 or thermally tolerant type D zooxanthellae of the genus Symbiodinium and can change dominant type following bleaching. We show that under controlled conditions, corals with type D symbionts grow 29% slower than those with type C2 symbionts. In the field, type D colonies grew 38% slower than C2 colonies. These results demonstrate the magnitude of trade-offs likely to be experienced by this species as they acclimatize to warmer conditions by changing to more thermally tolerant type D zooxanthellae. Irrespective of symbiont genotype, corals were affected to an even greater degree by the stress of a bleaching event which reduced growth by more than 50% for up to 18 months compared to pre-bleaching rates. The processes of symbiont change and acute thermal stress are likely to act in concert on coral growth as reefs acclimatize to more stressful warmer conditions, further compromising their regeneration capacity following climate change.

  12. Potential Costs of Acclimatization to a Warmer Climate: Growth of a Reef Coral with Heat Tolerant vs. Sensitive Symbiont Types

    Science.gov (United States)

    Jones, Alison; Berkelmans, Ray

    2010-01-01

    One of the principle ways in which reef building corals are likely to cope with a warmer climate is by changing to more thermally tolerant endosymbiotic algae (zooxanthellae) genotypes. It is highly likely that hosting a more heat-tolerant algal genotype will be accompanied by tradeoffs in the physiology of the coral. To better understand one of these tradeoffs, growth was investigated in the Indo-Pacific reef-building coral Acropora millepora in both the laboratory and the field. In the Keppel Islands in the southern Great Barrier Reef this species naturally harbors nrDNA ITS1 thermally sensitive type C2 or thermally tolerant type D zooxanthellae of the genus Symbiodinium and can change dominant type following bleaching. We show that under controlled conditions, corals with type D symbionts grow 29% slower than those with type C2 symbionts. In the field, type D colonies grew 38% slower than C2 colonies. These results demonstrate the magnitude of trade-offs likely to be experienced by this species as they acclimatize to warmer conditions by changing to more thermally tolerant type D zooxanthellae. Irrespective of symbiont genotype, corals were affected to an even greater degree by the stress of a bleaching event which reduced growth by more than 50% for up to 18 months compared to pre-bleaching rates. The processes of symbiont change and acute thermal stress are likely to act in concert on coral growth as reefs acclimatize to more stressful warmer conditions, further compromising their regeneration capacity following climate change. PMID:20454653

  13. Potential costs of acclimatization to a warmer climate: growth of a reef coral with heat tolerant vs. sensitive symbiont types.

    Science.gov (United States)

    Jones, Alison; Berkelmans, Ray

    2010-05-03

    One of the principle ways in which reef building corals are likely to cope with a warmer climate is by changing to more thermally tolerant endosymbiotic algae (zooxanthellae) genotypes. It is highly likely that hosting a more heat-tolerant algal genotype will be accompanied by tradeoffs in the physiology of the coral. To better understand one of these tradeoffs, growth was investigated in the Indo-Pacific reef-building coral Acropora millepora in both the laboratory and the field. In the Keppel Islands in the southern Great Barrier Reef this species naturally harbors nrDNA ITS1 thermally sensitive type C2 or thermally tolerant type D zooxanthellae of the genus Symbiodinium and can change dominant type following bleaching. We show that under controlled conditions, corals with type D symbionts grow 29% slower than those with type C2 symbionts. In the field, type D colonies grew 38% slower than C2 colonies. These results demonstrate the magnitude of trade-offs likely to be experienced by this species as they acclimatize to warmer conditions by changing to more thermally tolerant type D zooxanthellae. Irrespective of symbiont genotype, corals were affected to an even greater degree by the stress of a bleaching event which reduced growth by more than 50% for up to 18 months compared to pre-bleaching rates. The processes of symbiont change and acute thermal stress are likely to act in concert on coral growth as reefs acclimatize to more stressful warmer conditions, further compromising their regeneration capacity following climate change.

  14. Potential for timing high-energy marine inundation events in the recent geological past through age-dating of reef boulders in Fiji

    Science.gov (United States)

    Terry, James P.; Etienne, Samuel

    2014-12-01

    Transported coastal boulders have increasingly come to represent a valuable element of investigations within the broader framework of multi-proxy approaches applied to coastal hazard studies. Through a case study on Taveuni Island in Fiji, this paper outlines some approaches and hindrances to effective timing of prehistorical high-energy marine inundation events (storms and tsunamis) on tropical coastlines from the evidence of reef-platform carbonate boulders. Various sources of errors are outlined that investigators must consider when attempting to use carbonate boulder ages as a surrogate for timing past events. On Taveuni, uranium : thorium dates with a high level of precision (1-7 years) suggest that major inundation events have a return period of approximately 40-45 years since 1650 AD. Of particular importance, considerably different age dates are provided by coral samples sourced from the top and bottom (i.e. opposite faces) of individual boulders, so highlighting interpretation biases that must be avoided.

  15. Bleach vs. Bacteria

    Science.gov (United States)

    ... Articles | Inside Life Science Home Page Bleach vs. Bacteria By Sharon Reynolds Posted April 2, 2014 Your ... hypochlorous acid to help kill invading microbes, including bacteria. Researchers funded by the National Institutes of Health ...

  16. Climate warming, marine protected areas and the ocean-scale integrity of coral reef ecosystems.

    Directory of Open Access Journals (Sweden)

    Nicholas A J Graham

    Full Text Available Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the 1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure, diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales, with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance. This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should be integrated into existing management frameworks and combined with policies to improve system-wide resilience to climate variation and change.

  17. Climate warming, marine protected areas and the ocean-scale integrity of coral reef ecosystems.

    Science.gov (United States)

    Graham, Nicholas A J; McClanahan, Tim R; MacNeil, M Aaron; Wilson, Shaun K; Polunin, Nicholas V C; Jennings, Simon; Chabanet, Pascale; Clark, Susan; Spalding, Mark D; Letourneur, Yves; Bigot, Lionel; Galzin, René; Ohman, Marcus C; Garpe, Kajsa C; Edwards, Alasdair J; Sheppard, Charles R C

    2008-08-27

    Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the 1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure, diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales, with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance. This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should be integrated into existing management frameworks and combined with policies to improve system-wide resilience to climate variation and change.

  18. Coral bleaching data from Bleachwatch in the Florida Keys National Marine Sanctuary from 2016-05-17 to 2016-10-03 (NCEI Accession 0157068)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The initial onset of mass coral bleaching can vary among different species, geographic locations, types of reef zones and a fluctuation of severity, which makes it...

  19. Coral bleaching data from Bleachwatch in the Florida Keys National Marine Sanctuary from 2014-05-30 to 2014-11-11 (NODC Accession 0126654)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The initial onset of mass coral bleaching can vary among different species, geographic locations, types of reef zones and a fluctuation of severity, which makes it...

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

    Science.gov (United States)

    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

  1. Coral Reef Remote Sensing: Helping Managers Protect Reefs in a Changing Climate

    Science.gov (United States)

    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.

    2010-12-01

    Climate change and ocean acidification are already having severe impacts on coral reef ecosystems. Warming oceans have caused corals to bleach, or expel their symbiotic algae (zooxanthellae) with alarming frequency and severity and have contributed to a rise in coral infectious diseases. Ocean acidification is reducing the availability of carbonate ions needed by corals and many other marine organisms to build structural components like skeletons and shells and may already be slowing the coral growth. These two impacts are already killing corals and slowing reef growth, reducing biodiversity and the structure needed to provide crucial ecosystem services. NOAA’s Coral Reef Watch (CRW) uses a combination of satellite data, in situ observations, and models to provide coral reef managers, scientists, and others with information needed to monitor threats to coral reefs. The advance notice provided by remote sensing and models allows resource managers to protect corals, coral 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 coral bleaching on a global scale, ocean acidification in the Caribbean, and coral 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.

  2. Calcification and associated physiological parameters during a stress event in the scleractinian coral Stylophora pistillata.

    Science.gov (United States)

    Moya, Aurélie; Ferrier-Pagès, Christine; Furla, Paola; Richier, Sophie; Tambutté, Eric; Allemand, Denis; Tambutté, Sylvie

    2008-09-01

    High calcification rates observed in reef coral organisms are due to the symbiotic relationship established between scleractinian corals 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 corals and their zooxanthellae leads to bleaching. Bleaching is one of the major causes of the present decline of coral reefs related to climate change and anthropogenic activities. In our aquaria, corals experienced a chemical pollution leading to bleaching and ending with the death of corals. During the time course of this bleaching 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 corals at month 6.

  3. Modelling coral reef futures to inform management: can reducing local-scale stressors conserve reefs under climate change?

    Science.gov (United States)

    Gurney, Georgina G; Melbourne-Thomas, Jessica; Geronimo, Rollan C; Aliño, Perry M; Johnson, Craig R

    2013-01-01

    Climate change has emerged as a principal threat to coral reefs, and is expected to exacerbate coral reef degradation caused by more localised stressors. Management of local stressors is widely advocated to bolster coral reef resilience, but the extent to which management of local stressors might affect future trajectories of reef state remains unclear. This is in part because of limited understanding of the cumulative impact of multiple stressors. Models are ideal tools to aid understanding of future reef state under alternative management and climatic scenarios, but to date few have been sufficiently developed to be useful as decision support tools for local management of coral reefs subject to multiple stressors. We used a simulation model of coral reefs to investigate the extent to which the management of local stressors (namely poor water quality and fishing) might influence future reef state under varying climatic scenarios relating to coral bleaching. We parameterised the model for Bolinao, the Philippines, and explored how simulation modelling can be used to provide decision support for local management. We found that management of water quality, and to a lesser extent fishing, can have a significant impact on future reef state, including coral recovery following bleaching-induced mortality. The stressors we examined interacted antagonistically to affect reef state, highlighting the importance of considering the combined impact of multiple stressors rather than considering them individually. Further, by providing explicit guidance for management of Bolinao's reef system, such as which course of management action will most likely to be effective over what time scales and at which sites, we demonstrated the utility of simulation models for supporting management. Aside from providing explicit guidance for management of Bolinao's reef system, our study offers insights which could inform reef management more broadly, as well as general understanding of reef

  4. Modelling coral reef futures to inform management: can reducing local-scale stressors conserve reefs under climate change?

    Directory of Open Access Journals (Sweden)

    Georgina G Gurney

    Full Text Available Climate change has emerged as a principal threat to coral reefs, and is expected to exacerbate coral reef degradation caused by more localised stressors. Management of local stressors is widely advocated to bolster coral reef resilience, but the extent to which management of local stressors might affect future trajectories of reef state remains unclear. This is in part because of limited understanding of the cumulative impact of multiple stressors. Models are ideal tools to aid understanding of future reef state under alternative management and climatic scenarios, but to date few have been sufficiently developed to be useful as decision support tools for local management of coral reefs subject to multiple stressors. We used a simulation model of coral reefs to investigate the extent to which the management of local stressors (namely poor water quality and fishing might influence future reef state under varying climatic scenarios relating to coral bleaching. We parameterised the model for Bolinao, the Philippines, and explored how simulation modelling can be used to provide decision support for local management. We found that management of water quality, and to a lesser extent fishing, can have a significant impact on future reef state, including coral recovery following bleaching-induced mortality. The stressors we examined interacted antagonistically to affect reef state, highlighting the importance of considering the combined impact of multiple stressors rather than considering them individually. Further, by providing explicit guidance for management of Bolinao's reef system, such as which course of management action will most likely to be effective over what time scales and at which sites, we demonstrated the utility of simulation models for supporting management. Aside from providing explicit guidance for management of Bolinao's reef system, our study offers insights which could inform reef management more broadly, as well as general

  5. Modelling Coral Reef Futures to Inform Management: Can Reducing Local-Scale Stressors Conserve Reefs under Climate Change?

    Science.gov (United States)

    Gurney, Georgina G.; Melbourne-Thomas, Jessica; Geronimo, Rollan C.; Aliño, Perry M.; Johnson, Craig R.

    2013-01-01

    Climate change has emerged as a principal threat to coral reefs, and is expected to exacerbate coral reef degradation caused by more localised stressors. Management of local stressors is widely advocated to bolster coral reef resilience, but the extent to which management of local stressors might affect future trajectories of reef state remains unclear. This is in part because of limited understanding of the cumulative impact of multiple stressors. Models are ideal tools to aid understanding of future reef state under alternative management and climatic scenarios, but to date few have been sufficiently developed to be useful as decision support tools for local management of coral reefs subject to multiple stressors. We used a simulation model of coral reefs to investigate the extent to which the management of local stressors (namely poor water quality and fishing) might influence future reef state under varying climatic scenarios relating to coral bleaching. We parameterised the model for Bolinao, the Philippines, and explored how simulation modelling can be used to provide decision support for local management. We found that management of water quality, and to a lesser extent fishing, can have a significant impact on future reef state, including coral recovery following bleaching-induced mortality. The stressors we examined interacted antagonistically to affect reef state, highlighting the importance of considering the combined impact of multiple stressors rather than considering them individually. Further, by providing explicit guidance for management of Bolinao's reef system, such as which course of management action will most likely to be effective over what time scales and at which sites, we demonstrated the utility of simulation models for supporting management. Aside from providing explicit guidance for management of Bolinao's reef system, our study offers insights which could inform reef management more broadly, as well as general understanding of reef

  6. Coral Reef Community Composition in the Context of Disturbance History on the Great Barrier Reef, Australia

    Science.gov (United States)

    Graham, Nicholas A. J.; Chong-Seng, Karen M.; Huchery, Cindy; Januchowski-Hartley, Fraser A.; Nash, Kirsty L.

    2014-01-01

    Much research on coral reefs has documented differential declines in coral and associated organisms. In order to contextualise this general degradation, research on community composition is necessary in the context of varied disturbance histories and the biological processes and physical features thought to retard or promote recovery. We conducted a spatial assessment of coral reef communities across five reefs of the central Great Barrier Reef, Australia, with known disturbance histories, and assessed patterns of coral cover and community composition related to a range of other variables thought to be important for reef dynamics. Two of the reefs had not been extensively disturbed for at least 15 years prior to the surveys. Three of the reefs had been severely impacted by crown-of-thorns starfish outbreaks and coral bleaching approximately a decade before the surveys, from which only one of them was showing signs of recovery based on independent surveys. We incorporated wave exposure (sheltered and exposed) and reef zone (slope, crest and flat) into our design, providing a comprehensive assessment of the spatial patterns in community composition on these reefs. Categorising corals into life history groupings, we document major coral community differences in the unrecovered reefs, compared to the composition and covers found on the undisturbed reefs. The recovered reef, despite having similar coral cover, had a different community composition from the undisturbed reefs, which may indicate slow successional processes, or a different natural community dominance pattern due to hydrology and other oceanographic factors. The variables that best correlated with patterns in the coral community among sites included the density of juvenile corals, herbivore fish biomass, fish species richness and the cover of macroalgae. Given increasing impacts to the Great Barrier Reef, efforts to mitigate local stressors will be imperative to encouraging coral communities to persist into

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Kathryn L Markey

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

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    C A Downs

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  12. Climate change and the Great Barrier Reef

    International Nuclear Information System (INIS)

    Johnson, Johanna; Marshall, Paul

    2007-01-01

    Full text: Full text: Climate change is now recognised as the greatest long-term threat to the Great Barrier Reef (GBR). Managers face a future in which the impacts of climate change on tropical marine ecosystems are becoming increasingly frequent and severe. Further degradation is inevitable as the climate continues to change but the extent of the decline will depend on the rate and magnitude of climate change and the resilience of the ecosystem. Changes to the ecosystem have implications for the industries and regional communities that depend on the GBR. Climate projections for the GBR region include increasing air and sea temperatures, ocean acidification, nutrient enrichment (via changes in rainfall), altered light levels, more extreme weather events, changes to ocean circulation and sea level rise. Impacts have already been observed, with severe coral bleaching events in 1998 and 2002, and mass mortalities of seabirds linked to anomalously warm summer conditions. Climate change also poses significant threats to the industries and communities that depend on the GBR ecosystem, both directly and indirectly through loss of natural resources; industries such as recreational and commercial fishing, and tourism, which contributes to a regional tourism industry worth $6.1 billion (Access Economics 2005). A vulnerability assessment undertaken by leading experts in climate and marine science identified climate sensitivities for GBR species, habitats, key processes, GBR industries and communities (Johnson and Marshall 2007). This information has been used to develop a Climate Change Action Plan for the GBR. The Action Plan is a five-year program aimed at facilitating targeted science, building a resilient ecosystem, assisting adaptation of industries and communities, and reducing climate footprints. The Action Plan identifies strategies to review current management arrangements and raise awareness of the issue in order to work towards a resilient ecosystem. Integral to

  13. Site-specific variation in gene expression from Symbiodinium spp. associated with offshore and inshore Porites astreoides in the lower Florida Keys is lost with bleaching and disease stress.

    Science.gov (United States)

    Salas, Briana Hauff; Haslun, Joshua A; Strychar, Kevin B; Ostrom, Peggy H; Cervino, James M

    2017-01-01

    Scleractinian coral are experiencing unprecedented rates of mortality due to increases in sea surface temperatures in response to global climate change. Some coral species however, survive high temperature events due to a reduced susceptibility to bleaching. We investigated the relationship between bleaching susceptibility and expression of five metabolically related genes of Symbiodinium spp. from the coral Porites astreoides originating from an inshore and offshore reef in the Florida Keys. The acclimatization potential of Symbiodinium spp. to changing temperature regimes was also measured via a two-year reciprocal transplant between the sites. Offshore coral fragments displayed significantly higher expression in Symbiodinium spp. genes PCNA, SCP2, G3PDH, PCP and psaE than their inshore counterparts (pzooxanthellae observed under conditions of chronic moderate stress is lost under the acute extreme conditions studied here.

  14. Increased cell proliferation and mucocyte density in the sea anemone Aiptasia pallida recovering from bleaching.

    Directory of Open Access Journals (Sweden)

    David Fransolet

    Full Text Available Recovery of coral after bleaching episodes is a critical period for the health of the reef ecosystem. While events such as symbiont (genus Symbiodinium shifting/shuffling or tissue apoptosis have been demonstrated to occur following bleaching, little is known concerning tissue recovery or cell proliferation. Here, we studied the sea anemone Aiptasia pallida exposed to a transient elevation of water temperature combined with high illumination (33°C and 1900 µmol photons x m(-2 x s(-1 for 30 h. Following such treatment bleached anemones showed a significant reduction of their Symbiodinium density. Cell proliferation in the ectodermis and gastrodermis was determined by assessing the densities of cells labeled with a thymidine analogue (EdU. Cell proliferation significantly increased during the first day following stress in both tissue types. This increased cell proliferation returned to pre-stress values after one week. Although cell proliferation was higher in the ectodermis in absence of stress, it was relatively more pronounced in the gastrodermis of stressed anemones. In addition, the ratio of ectodermal mucocytes significantly increased three weeks after induced stress. These results suggest that thermal/photic stress coupled with the loss of the symbionts is able to enhance cell proliferation in both gastrodermis and ectodermis of cnidarians. While new cells formed in the gastrodermis are likely to host new Symbiodinium, the fate of new cells in the ectodermis was only partially revealed. Some new ectodermal cells may, in part, contribute to the increased number of mucocytes which could eventually help strengthen the heterotrophic state until restoration of the symbiosis.

  15. Breakdown of the coral-algae symbiosis: towards formalising a linkage between warm-water bleaching thresholds and the growth rate of the intracellular zooxanthellae

    Directory of Open Access Journals (Sweden)

    S. A. Wooldridge

    2013-03-01

    Full Text Available Impairment of the photosynthetic machinery of the algal endosymbiont ("zooxanthellae" is the proximal driver of the thermal breakdown of the coral-algae symbiosis ("coral bleaching". Yet, the initial site of damage, and early dynamics of the impairment are still not well resolved. In this perspective essay, I consider further a recent hypothesis which proposes an energetic disruption to the carbon-concentrating mechanisms (CCMs of the coral host, and the resultant onset of CO2-limitation within the photosynthetic "dark reactions" as a unifying cellular mechanism. The hypothesis identifies the enhanced retention of photosynthetic carbon for zooxanthellae (regrowth following an initial irradiance-driven expulsion event as a strong contributing cause of the energetic disruption. If true, then it implies that the onset of the bleaching syndrome and setting of upper thermal bleaching limits are emergent attributes of the coral symbiosis that are ultimately underpinned by the characteristic growth profile of the intracellular zooxanthellae; which is known to depend not just on temperature, but also external (seawater nutrient availability and zooxanthellae genotype. Here, I review this proposed bleaching linkage at a variety of observational scales, and find it to be parsimonious with the available evidence. Future experiments are suggested that can more formally test the linkage. If correct, the new cellular model delivers a valuable new perspective to consider the future prospects of the coral symbiosis in an era of rapid environmental change, including: (i the underpinning mechanics (and biological significance of observed changes in resident zooxanthellae genotypes, and (ii the now crucial importance of reef water quality in co-determining thermal bleaching resistance.

  16. Breakdown of the coral-algae symbiosis: towards formalising a linkage between warm-water bleaching thresholds and the growth rate of the intracellular zooxanthellae

    Science.gov (United States)

    Wooldridge, S. A.

    2013-03-01

    Impairment of the photosynthetic machinery of the algal endosymbiont ("zooxanthellae") is the proximal driver of the thermal breakdown of the coral-algae symbiosis ("coral bleaching"). Yet, the initial site of damage, and early dynamics of the impairment are still not well resolved. In this perspective essay, I consider further a recent hypothesis which proposes an energetic disruption to the carbon-concentrating mechanisms (CCMs) of the coral host, and the resultant onset of CO2-limitation within the photosynthetic "dark reactions" as a unifying cellular mechanism. The hypothesis identifies the enhanced retention of photosynthetic carbon for zooxanthellae (re)growth following an initial irradiance-driven expulsion event as a strong contributing cause of the energetic disruption. If true, then it implies that the onset of the bleaching syndrome and setting of upper thermal bleaching limits are emergent attributes of the coral symbiosis that are ultimately underpinned by the characteristic growth profile of the intracellular zooxanthellae; which is known to depend not just on temperature, but also external (seawater) nutrient availability and zooxanthellae genotype. Here, I review this proposed bleaching linkage at a variety of observational scales, and find it to be parsimonious with the available evidence. Future experiments are suggested that can more formally test the linkage. If correct, the new cellular model delivers a valuable new perspective to consider the future prospects of the coral symbiosis in an era of rapid environmental change, including: (i) the underpinning mechanics (and biological significance) of observed changes in resident zooxanthellae genotypes, and (ii) the now crucial importance of reef water quality in co-determining thermal bleaching resistance.

  17. CORAL CONDITION: HOW TO FATHOM THE DECLINE OF CORAL REEF ECOSYSTEMS

    Science.gov (United States)

    Coral reefs have experienced unprecedented levels of bleaching, 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.

  18. The Stability of the Giant Clam Holobiont over Time and during Bleaching Stress

    KAUST Repository

    Pappas, Melissa

    2017-12-01

    The stability of marine photosymbiotic holobionts has major implications for the future of coral reef communities. This study aims to describe the stability of the Red Sea giant clam holobiont over the duration of one year and during induced bleaching stress under laboratory thermal manipulations. Tridacnid clams of the species Tridacna maxima were sampled at three reef locations near the central Saudi coast of the Red Sea. Associated Symbiodinium of Red Sea giant clams have previously been described to be part of only Clade A, which suggests a strong specificity in the clam-algal partnership, but specific types and potential shifting of types within this clade have not been examined for giant clams. The results from this study confirm that tridacnid symbiont types shift over time and the change between three A1 types suggests a biological and functional significance of two undescribed A1 Symbiodinium types. Experimental bleaching shows that Red Sea giant clams, although exposed to rather hot temperatures naturally, will bleach at 34°C after two weeks, and severely bleached clams likely will not recover. During bleaching, Symbiodinium types shift as well, and shift more drastically than seasonal shifts during the year. This shifting may be an evolved characteristic of the giant clam to aid in surviving major changes in the environment. However, more research is needed to determine if these holobionts are capable of keeping up with the global forecast of warming in reef environments.

  19. Bleaching of Wool with Sodium Borohydride

    OpenAIRE

    Duygu Yilmazer, MSc.; Mehmet Kanik, Ph.D.

    2009-01-01

    An untreated wool fabric was bleached both with sodium borohydride (SBH) in the presence of sodium bisulphite (SBS) solution and with a commercial H2O2 bleaching method. The concentration effects of SBH and SBS, bleaching time, pH and temperature on SBH bleaching process were investigated. Whiteness, yellowness and alkali solubility results were assessed for both bleaching methods. The results showed that whiteness degrees obtained with SBH bleaching was comparable with that of H2O2 bleaching...

  20. Community structure and coral status across reef fishing intensity gradients in Palk Bay reef, southeast coast of India.

    Digital Repository Service at National Institute of Oceanography (India)

    Manikandan, B.; Ravindran, J.; Shrinivaasu, S.; Marimuthu, N.; Paramasivam, K.

    to the reefs (McClanahan et al. 2006). However, majority of the MPAs lack effective enforcement of laws leading to reef damage and over exploitation (Mora et al. 2006). Climate change and Ocean acidification are chronic processes that exert their effects at a... availability for macroalgal attachment and nutrient enrichment will enhance the algal population in the coral ecosystems (McManus and Polsenberg 2004). Algal domination in a coral ecosystem has severe ecological implications including coral bleaching (Hughes...

  1. Climate-driven coral reorganisation influences aggressive behaviour in juvenile coral-reef fishes

    Science.gov (United States)

    Kok, Judith E.; Graham, Nicholas A. J.; Hoogenboom, Mia O.

    2016-06-01

    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 coral 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 coral). Patch reefs were constructed to simulate two types of reefs: present-day reefs that are vulnerable to climate-induced coral bleaching, and reefs with more bleaching-robust coral taxa, thereby simulating the likely future of coral 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 coral-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 coral 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 coral-obligate P. moluccensis. This study highlights the importance of coral composition as a determinant of behaviour and diversity of coral-reef fishes.

  2. BLEACHING NEPTUNE BALLS

    Directory of Open Access Journals (Sweden)

    BONET Maria Angeles

    2014-05-01

    Full Text Available Posidonia Oceanic is a seaweed from Mediterranean Sea and it is more concentrated at the Balerian SEA. This implies the Valencian Community also. It forms vaste underwater meadows in the sea and are part of the Mediterranean ecosystem. It is a sea-grass specie with fruits and flowers. Leaves are ribbon-like and they grow in winter and at the end of summer some of them are separated and arrive to some sea line. Fuit is separated and can floate, it is known as “the olive of the sea” mainly in Italy, or as the Neptune Balls. As it can be used in different fields, it is is being studied in order ro have the precitice tests. Some authors have reported the manufacturing of fully bio-based comites with a gluten matrix by hot-press molding. And it has been considered as an effective insulator for building industry or even though to determine the presence of mercure in the Mediterranean sea some years ago. As many applications can be designed from that fibers, it has been considered to be bleached in order to used them in fashionable products. Consequently, its original brown color is not the most suitable one and it should be bleached as many other cellulosic fibers. The aim of this paper is to bleache neptune balls however, the inner fibers were not accessible at all and it implied not to bleach the inner fibers in the neptune ball. Further studiesd will consider bleaching the individualized fibers.

  3. Synergistic impacts of global warming on the resilience of coral reefs

    OpenAIRE

    Bozec, Yves-Marie; Mumby, Peter J.

    2015-01-01

    Recent epizootics have removed important functional species from Caribbean coral reefs and left communities vulnerable to alternative attractors. Global warming will impact reefs further through two mechanisms. A chronic mechanism reduces coral calcification, which can result in depressed somatic growth. An acute mechanism, coral bleaching, causes extreme mortality when sea temperatures become anomalously high. We ask how these two mechanisms interact in driving future reef state (coral cover...

  4. Habitat dynamics, marine reserve status, and the decline and recovery of coral reef fish communities

    Science.gov (United States)

    Williamson, David H; Ceccarelli, Daniela M; Evans, Richard D; Jones, Geoffrey P; Russ, Garry R

    2014-01-01

    Severe climatic disturbance events often have major impacts on coral reef communities, generating cycles of decline and recovery, and in some extreme cases, community-level phase shifts from coral-to algal-dominated states. Benthic habitat changes directly affect reef fish communities, with low coral cover usually associated with low fish diversity and abundance. No-take marine reserves (NTRs) are widely advocated for conserving biodiversity and enhancing the sustainability of exploited fish populations. Numerous studies have documented positive ecological and socio-economic benefits of NTRs; however, the ability of NTRs to ameliorate the effects of acute disturbances on coral reefs has seldom been investigated. Here, we test these factors by tracking the dynamics of benthic and fish communities, including the important fishery species, coral trout (Plectropomus spp.), over 8 years in both NTRs and fished areas in the Keppel Island group, Great Barrier Reef, Australia. Two major disturbances impacted the reefs during the monitoring period, a coral bleaching event in 2006 and a freshwater flood plume in 2011. Both disturbances generated significant declines in coral cover and habitat complexity, with subsequent declines in fish abundance and diversity, and pronounced shifts in fish assemblage structure. Coral trout density also declined in response to the loss of live coral, however, the approximately 2:1 density ratio between NTRs and fished zones was maintained over time. The only post-disturbance refuges for coral trout spawning stocks were within the NTRs that escaped the worst effects of the disturbances. Although NTRs had little discernible effect on the temporal dynamics of benthic or fish communities, it was evident that the post-disturbance refuges for coral trout spawning stocks within some NTRs may be critically important to regional-scale population persistence and recovery. PMID:24634720

  5. Greenhouse role in reef stress unproven

    International Nuclear Information System (INIS)

    Roberts, L.

    1991-01-01

    In the late 1980s, as coral reefs throughout the Caribbean and elsewhere fell victim to a phenomenon known as bleaching, a few scientists stated that greenhouse warming is upon us and that the exquisitely sensitive corals, reacting to elevated water temperatures, are serving as biological sentinels. This stirred up so much concern that Congress assigned the National Science Foundation (NSF) to investigate the connection between coral bleaching and global warming. Late last month investigators at an NSF-sponsored meeting rendered their verdict. Following the Miami meeting, which brought together, for the first time, climatologists, oceanographers, and meteorologists with marine biologists, ecologists, and other reef experts, the participants issued a statement saying essentially that, yes, higher temperatures seem to be at least partly at fault but, no, greenhouse warming cannot be blamed

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

    Science.gov (United States)

    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. © 2013 John Wiley & Sons Ltd.

  7. Bleaching response of Symbiodinium (zooxanthellae): determination by flow cytometry.

    Science.gov (United States)

    Lee, Co Sin; Yeo, Yin Sheng Wilson; Sin, Tsai Min

    2012-10-01

    Coral bleaching is of increasing concern to reef management and stakeholders. Thus far, quantification of coral bleaching tends to be heavily reliant on the enumeration of zooxanthellae, with less emphasis on assessment of photosynthetic or physiological condition, these being often assessed separately by techniques such as liquid chromatography. Traditional methods of enumeration using microscopy are time consuming, subjected to low precision and great observer error. In this study, we presented a method for the distinction of physoiological condition and rapid enumeration of zooxanthellae using flow cytometry (FCM). Microscopy verified that healthy looking/live versus damaged/dead zooxanthellae could be reliably and objectively distinguished and counted by FCM on the basis of red and green fluorescence and light scatter. Excellent correlations were also determined between FCM and microscopy estimates of cell concentrations of fresh zooxanthellae isolates from Pocillopora damicornis. The relative intensities of chlorophyll and β-carotene fluorescences were shown to be important in understanding the results of increased cell counts in freshly isolated zooxanthellae experimentally exposed to high temperatures (34, 36, and 38°C) over 24 h, with ambient temperature (29°C) used as controls. The ability to simultaneously identify and enumerate subpopulations of different physiological states in the same sample provides an enormous advantage in not just determining bleaching responses, but elucidating adaptive response and mechanisms for tolerance. Therefore, this approach might provide a rapid, convenient, and reproducible methodology for climate change studies and reef management programs. Copyright © 2012 International Society for Advancement of Cytometry.

  8. Mapping Prevalence and Incidence of Coral Disease in reef-building corals at two Natural Reserves of the Southwest Puerto Rico

    Science.gov (United States)

    Sanchez Viruet, I.; Irizarry-Soto, E.; Ruiz-Valentín, I.

    2016-02-01

    Coral diseases seems to be the main cause of coral reef decline in the Caribbean. Before the bleaching event of 2005, coral reefs in Puerto Rico were dominated by the reef-building taxa: Orbicella annularis, Porites astreoides, Montastrea cavernosa, Agaricia agaracites and Colpophyllia natans. After the event, live-coral cover significantly declined and more than 90% of the scleractinian corals in the U.S. Virgin Islands and Puerto Rico showed signals of thermal stressors. The prevalence of coral diseases in five reef-building coral (Orbicella annularis, Orbicella franksi, Orbicella faveolata, Porites porites and Pseudiploria strigosa) species was assessed by tagging, photographing, and mapping all diseased and healthy colonies within 10 permanent 40m2 band transects at each inshore and mid-shelf reefs of Belvedere and Punta Guaniquilla Natural Reserves using a random stratified sampling method. Maximum and perpendicular diameter was used to assess coral size using Coral Point Count with Excel Extension. Corals were classified into three size class populations (class I: 0-50cm, class II: 50-100cm and class III: >100 cm). Data was used to develop a GIS-based map containing coral species, size and disease presence. Preliminary results of the inshore area showed a higher disease prevalence in Belvedere natural reserve and for P. strigosa (17.1%) and O. annularis (9.3%). Frequency distribution analysis showed a dominance of O. faveolata at Punta Guaniquilla and Belvedere (127 and 88 individuals respectively). Size class I dominates the distribution of each species within the natural reserves with a higher disease prevalence. Future work include continue prevalence surveys of the outer reef shelf on both natural reserves, monitoring and GIS-based mapping of incidence and resilience through time. This study will help in the assessment of the status of the coral reef of the southwest insular platform.

  9. Bleaching response of coral species in the context of assemblage response

    Science.gov (United States)

    Swain, Timothy D.; DuBois, Emily; Goldberg, Scott J.; Backman, Vadim; Marcelino, Luisa A.

    2017-06-01

    Caribbean coral reefs are declining due to a mosaic of local and global stresses, including climate change-induced thermal stress. Species and assemblage responses differ due to factors that are not easily identifiable or quantifiable. We calculated a novel species-specific metric of coral bleaching response, taxon- α and - β, which relates the response of a species to that of its assemblages for 16 species over 18 assemblages. By contextualizing species responses within the response of their assemblages, the effects of environmental factors are removed and intrinsic differences among taxa are revealed. Most corals experience either a saturation response, overly sensitive to weak stress ( α > 0) but under-responsive compared to assemblage bleaching ( β bleaching ( β > 1). This metric may help reveal key factors of bleaching susceptibility and identify species as targets for conservation.

  10. Contrasting Patterns of Coral Bleaching Susceptibility in 2010 Suggest an Adaptive Response to Thermal Stress

    Science.gov (United States)

    Guest, James R.; Baird, Andrew H.; Maynard, Jeffrey A.; Muttaqin, Efin; Edwards, Alasdair J.; Campbell, Stuart J.; Yewdall, Katie; Affendi, Yang Amri; Chou, Loke Ming

    2012-01-01

    Background Coral bleaching events vary in severity, however, to date, the hierarchy of susceptibility to bleaching among coral taxa has been consistent over a broad geographic range and among bleaching episodes. Here we examine the extent of spatial and temporal variation in thermal tolerance among scleractinian coral taxa and between locations during the 2010 thermally induced, large-scale bleaching event in South East Asia. Methodology/Principal Findings Surveys to estimate the bleaching and mortality indices of coral genera were carried out at three locations with contrasting thermal and bleaching histories. Despite the magnitude of thermal stress being similar among locations in 2010, there was a remarkable contrast in the patterns of bleaching susceptibility. Comparisons of bleaching susceptibility within coral taxa and among locations revealed no significant differences between locations with similar thermal histories, but significant differences between locations with contrasting thermal histories (Friedman = 34.97; pSingapore, where only 5% and 12% of colonies died. Conclusions/Significance The pattern of susceptibility among coral genera documented here is unprecedented. A parsimonious explanation for these results is that coral populations that bleached during the last major warming event in 1998 have adapted and/or acclimatised to thermal stress. These data also lend support to the hypothesis that corals in regions subject to more variable temperature regimes are more resistant to thermal stress than those in less variable environments. PMID:22428027

  11. Calcification rate and the stable carbon, oxygen, and nitrogen isotopes in the skeleton, host tissue, and zooxanthellae of bleached and recovering Hawaiian corals

    Science.gov (United States)

    Rodrigues, Lisa J.; Grottoli, Andréa G.

    2006-06-01

    We tested the effectiveness of stable isotopes as recorders of physiological changes that occur during coral bleaching and recovery. Montipora capitata and Porites compressa fragments were bleached in outdoor tanks with seawater temperature raised to 30 °C (treatment corals) for one month. Additional fragments were maintained at 27 °C in separate tanks (control corals). After one month, (0 months recovery), buoyant weight was measured and a subset of fragments was frozen. Remaining fragments were returned to the reef for recovery. After 1.5, 4, and 8 months, fragments were collected, measured for buoyant weight, and frozen. Fragments were analyzed for stable carbon and oxygen isotopic compositions of the skeleton (δ 13C s; δ 18O s) and nitrogen and carbon isotopic compositions of the host tissue (δ 15N h; δ 13C h) and zooxanthellae (δ 15N z; δ 13C z). δ 13C s decreased immediately after bleaching in M. capitata, but not in P. compressa. δ 18O s of both species failed to record the warming event. During the remaining months of recovery, δ 13C s and δ 18O s were more enriched in treatment than control corals due to decreases in calcification and metabolic fractionation during that time. Increased δ 15N h of treatment P. compressa may be due to expelled zooxanthellae during bleaching and recovery. Increased δ 15N z at 1.5 months in treatment fragments of both species reflects the increased incorporation of dissolved inorganic nitrogen to facilitate mitotic cell division and/or chl a/cell recovery. Changes in δ 13C h and δ 13C z at 1.5 months in treatment M. capitata indicated a large increase in heterotrophically acquired carbon relative to photosynthetically fixed carbon. We experimentally show that isotopes in coral skeleton, host tissue and zooxanthellae can be used to verify physiological changes during bleaching and recovery, but their use as a proxy for past bleaching events in the skeletal record is limited.

  12. Reef calcifiers are adapted to episodic heat stress but vulnerable to sustained warming.

    Science.gov (United States)

    Stuhr, Marleen; Reymond, Claire E; Rieder, Vera; Hallock, Pamela; Rahnenführer, Jörg; Westphal, Hildegard; Kucera, Michal

    2017-01-01

    Shallow marine ecosystems naturally experience fluctuating physicochemical conditions across spatial and temporal scales. Widespread coral-bleaching events, induced by prolonged heat stress, highlight the importance of how the duration and frequency of thermal stress influence the adaptive physiology of photosymbiotic calcifiers. Large benthic foraminifera harboring algal endosymbionts are major tropical carbonate producers and bioindicators of ecosystem health. Like corals, they are sensitive to thermal stress and bleach at temperatures temporarily occurring in their natural habitat and projected to happen more frequently. However, their thermal tolerance has been studied so far only by chronic exposure, so how they respond under more realistic episodic heat-event scenarios remains unknown. Here, we determined the physiological responses of Amphistegina gibbosa, an abundant western Atlantic foraminifera, to four different treatments--control, single, episodic, and chronic exposure to the same thermal stress (32°C)--in controlled laboratory cultures. Exposure to chronic thermal stress reduced motility and growth, while antioxidant capacity was elevated, and photosymbiont variables (coloration, oxygen-production rates, chlorophyll a concentration) indicated extensive bleaching. In contrast, single- and episodic-stress treatments were associated with higher motility and growth, while photosymbiont variables remained stable. The effects of single and episodic heat events were similar, except for the presumable occurrence of reproduction, which seemed to be suppressed by both episodic and chronic stress. The otherwise different responses between treatments with thermal fluctuations and chronic stress indicate adaptation to thermal peaks, but not to chronic exposure expected to ensue when baseline temperatures are elevated by climate change. This firstly implies that marine habitats with a history of fluctuating thermal stress potentially support resilient

  13. Local-scale projections of coral reef futures and implications of the Paris Agreement.

    Science.gov (United States)

    van Hooidonk, Ruben; Maynard, Jeffrey; Tamelander, Jerker; Gove, Jamison; Ahmadia, Gabby; Raymundo, Laurie; Williams, Gareth; Heron, Scott F; Planes, Serge

    2016-12-21

    Increasingly frequent severe coral bleaching is among the greatest threats to coral reefs posed by climate change. Global climate models (GCMs) project great spatial variation in the timing of annual severe bleaching (ASB) conditions; a point at which reefs are certain to change and recovery will be limited. However, previous model-resolution projections (~1 × 1°) are too coarse to inform conservation planning. To meet the need for higher-resolution projections, we generated statistically downscaled projections (4-km resolution) for all coral reefs; these projections reveal high local-scale variation in ASB. Timing of ASB varies >10 years in 71 of the 87 countries and territories with >500 km 2 of reef area. Emissions scenario RCP4.5 represents lower emissions mid-century than will eventuate if pledges made following the 2015 Paris Climate Change Conference (COP21) become reality. These pledges do little to provide reefs with more time to adapt and acclimate prior to severe bleaching conditions occurring annually. RCP4.5 adds 11 years to the global average ASB timing when compared to RCP8.5; however, >75% of reefs still experience ASB before 2070 under RCP4.5. Coral reef futures clearly vary greatly among and within countries, indicating the projections warrant consideration in most reef areas during conservation and management planning.

  14. Artificial Reefs

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — An artificial reef is a human-made underwater structure, typically built to promote marine life in areas with a generally featureless bottom, control erosion, block...

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

    Science.gov (United States)

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

    2018-03-01

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

  16. Coral bleaching and ocean ''hot spots''

    Energy Technology Data Exchange (ETDEWEB)

    Goreau, T.J. (Global Coral Reef Alliance, Chappaqua, NY (United States)); Hayes, R.L. (Howard Univ., Washington, DC (United States). College of Medicine)

    1994-05-01

    Global sea-surface temperature maps show that mass coral-reef bleaching episodes between 1983 and 1991 followed positive anomalies more than 1 deg C above long-term monthly averages (''hot spots'') during the preceding warm season. Irregular formation, movement, and disappearance of hot spots make their detailed long-term prediction impossible, but they can be tracked in real time from satellite data. Monitoring of ocean hot spots and of coral bleaching is needed if the Framework Convention of Climate Change is to meet its goal of protecting the most temperature sensitive ecosystems. 47 refs, 3 figs

  17. Large-scale coral recruitment patterns on Mona Island, Puerto Rico: evidence of a transitional community trajectory after massive coral bleaching and mortality

    Directory of Open Access Journals (Sweden)

    Edwin A. Hernández-Delgado

    2014-09-01

    Full Text Available Coral reefs have largely declined across the northeastern Caribbean following the 2005 massive bleaching event. Climate change-related sea surface warming and coral disease outbreaks of a white plague-like syndrome and of yellow band disease (YBD have caused significant coral decline affecting massive reef building species (i.e., Orbicella annularis species complex which show no apparent signs of recovery through larval sexual recruitment. We addressed coral recruit densities across three spur and groove reef locations along the western shelf of remote Mona Island, Puerto Rico: Punta Capitán (PCA, Pasa de Las Carmelitas (PLC, and Las Carmelitas-South (LCS. Data were collected during November 2012 along 93 haphazard transects across three depth zones (<5m, 5-10m, 10-15m. A total of 32 coral species (9 octocorals, 1 hydrocoral, 22 scleractinians were documented among the recruit community. Communities had low densities and dominance by short-lived brooder species seven years after the 2005 event. Mean coral recruit density ranged from 1.2 to 10.5/m2 at PCA, 6.3 to 7.2/m² at LCS, 4.5 to 9.5/m² at PLC. Differences in coral recruit community structure can be attributed to slight variation in percent macroalgal cover and composition as study sites had nearly similar benthic spatial heterogeneity. Dominance by ephemeral coral species was widespread. Recovery of largely declining massive reef-building species such as the O. annularis species complex was limited or non-existent. The lack of recovery could be the combined result of several mechanisms involving climate change, YBD disease, macroalgae, fishing, urchins and Mona Island’s reefs limited connectivity to other reef systems. There is also for rehabilitation of fish trophic structure, with emphasis in recovering herbivore guilds and depleted populations of D. antillarum. Failing to recognize the importance of ecosystem-based management and resilience rehabilitation may deem remote coral reefs

  18. Virus-host interactions and their roles in coral reef health and disease.

    Science.gov (United States)

    Thurber, Rebecca Vega; Payet, Jérôme P; Thurber, Andrew R; Correa, Adrienne M S

    2017-04-01

    Coral reefs occur in nutrient-poor shallow waters, constitute biodiversity and productivity hotspots, and are threatened by anthropogenic disturbance. This Review provides an introduction to coral reef virology and emphasizes the links between viruses, coral mortality and reef ecosystem decline. We describe the distinctive benthic-associated and water-column- associated viromes that are unique to coral reefs, which have received less attention than viruses in open-ocean systems. We hypothesize that viruses of bacteria and eukaryotes dynamically interact with their hosts in the water column and with scleractinian (stony) corals to influence microbial community dynamics, coral bleaching and disease, and reef biogeochemical cycling. Last, we outline how marine viruses are an integral part of the reef system and suggest that the influence of viruses on reef function is an essential component of these globally important environments.

  19. Contrasting patterns of coral bleaching susceptibility in 2010 suggest an adaptive response to thermal stress.

    Science.gov (United States)

    Guest, James R; Baird, Andrew H; Maynard, Jeffrey A; Muttaqin, Efin; Edwards, Alasdair J; Campbell, Stuart J; Yewdall, Katie; Affendi, Yang Amri; Chou, Loke Ming

    2012-01-01

    Coral bleaching events vary in severity, however, to date, the hierarchy of susceptibility to bleaching among coral taxa has been consistent over a broad geographic range and among bleaching episodes. Here we examine the extent of spatial and temporal variation in thermal tolerance among scleractinian coral taxa and between locations during the 2010 thermally induced, large-scale bleaching event in South East Asia. Surveys to estimate the bleaching and mortality indices of coral genera were carried out at three locations with contrasting thermal and bleaching histories. Despite the magnitude of thermal stress being similar among locations in 2010, there was a remarkable contrast in the patterns of bleaching susceptibility. Comparisons of bleaching susceptibility within coral taxa and among locations revealed no significant differences between locations with similar thermal histories, but significant differences between locations with contrasting thermal histories (Friedman = 34.97; pBleaching was much less severe at locations that bleached during 1998, that had greater historical temperature variability and lower rates of warming. Remarkably, Acropora and Pocillopora, taxa that are typically highly susceptible, although among the most susceptible in Pulau Weh (Sumatra, Indonesia) where respectively, 94% and 87% of colonies died, were among the least susceptible in Singapore, where only 5% and 12% of colonies died. The pattern of susceptibility among coral genera documented here is unprecedented. A parsimonious explanation for these results is that coral populations that bleached during the last major warming event in 1998 have adapted and/or acclimatised to thermal stress. These data also lend support to the hypothesis that corals in regions subject to more variable temperature regimes are more resistant to thermal stress than those in less variable environments.

  20. Unprecedented Mass Bleaching and Loss of Coral across 12° of Latitude in Western Australia in 2010–11

    Science.gov (United States)

    Moore, James A. Y.; Bellchambers, Lynda M.; Depczynski, Martial R.; Evans, Richard D.; Evans, Scott N.; Field, Stuart N.; Friedman, Kim J.; Gilmour, James P.; Holmes, Thomas H.; Middlebrook, Rachael; Radford, Ben T.; Ridgway, Tyrone; Shedrawi, George; Taylor, Heather; Thomson, Damian P.; Wilson, Shaun K.

    2012-01-01

    Background Globally, coral bleaching has been responsible for a significant decline in both coral cover and diversity over the past two decades. During the summer of 2010–11, anomalous large-scale ocean warming induced unprecedented levels of coral bleaching accompanied by substantial storminess across more than 12° of latitude and 1200 kilometers of coastline in Western Australia (WA). Methodology/Principal Findings Extreme La-Niña conditions caused extensive warming of waters and drove considerable storminess and cyclonic activity across WA from October 2010 to May 2011. Satellite-derived sea surface temperature measurements recorded anomalies of up to 5°C above long-term averages. Benthic surveys quantified the extent of bleaching at 10 locations across four regions from tropical to temperate waters. Bleaching was recorded in all locations across regions and ranged between 17% (±5.5) in the temperate Perth region, to 95% (±3.5) in the Exmouth Gulf of the tropical Ningaloo region. Coincident with high levels of bleaching, three cyclones passed in close proximity to study locations around the time of peak temperatures. Follow-up surveys revealed spatial heterogeneity in coral cover change with four of ten locations recording significant loss of coral cover. Relative decreases ranged between 22%–83.9% of total coral cover, with the greatest losses in the Exmouth Gulf. Conclusions/Significance The anomalous thermal stress of 2010–11 induced mass bleaching of corals along central and southern WA coral reefs. Significant coral bleaching was observed at multiple locations across the tropical-temperate divide spanning more than 1200 km of coastline. Resultant spatially patchy loss of coral cover under widespread and high levels of bleaching and cyclonic activity, suggests a degree of resilience for WA coral communities. However, the spatial extent of bleaching casts some doubt over hypotheses suggesting that future impacts to coral reefs under forecast

  1. Unprecedented mass bleaching and loss of coral across 12° of latitude in Western Australia in 2010-11.

    Science.gov (United States)

    Moore, James A Y; Bellchambers, Lynda M; Depczynski, Martial R; Evans, Richard D; Evans, Scott N; Field, Stuart N; Friedman, Kim J; Gilmour, James P; Holmes, Thomas H; Middlebrook, Rachael; Radford, Ben T; Ridgway, Tyrone; Shedrawi, George; Taylor, Heather; Thomson, Damian P; Wilson, Shaun K

    2012-01-01

    Globally, coral bleaching has been responsible for a significant decline in both coral cover and diversity over the past two decades. During the summer of 2010-11, anomalous large-scale ocean warming induced unprecedented levels of coral bleaching accompanied by substantial storminess across more than 12° of latitude and 1200 kilometers of coastline in Western Australia (WA). Extreme La-Niña conditions caused extensive warming of waters and drove considerable storminess and cyclonic activity across WA from October 2010 to May 2011. Satellite-derived sea surface temperature measurements recorded anomalies of up to 5°C above long-term averages. Benthic surveys quantified the extent of bleaching at 10 locations across four regions from tropical to temperate waters. Bleaching was recorded in all locations across regions and ranged between 17% (±5.5) in the temperate Perth region, to 95% (±3.5) in the Exmouth Gulf of the tropical Ningaloo region. Coincident with high levels of bleaching, three cyclones passed in close proximity to study locations around the time of peak temperatures. Follow-up surveys revealed spatial heterogeneity in coral cover change with four of ten locations recording significant loss of coral cover. Relative decreases ranged between 22%-83.9% of total coral cover, with the greatest losses in the Exmouth Gulf. The anomalous thermal stress of 2010-11 induced mass bleaching of corals along central and southern WA coral reefs. Significant coral bleaching was observed at multiple locations across the tropical-temperate divide spanning more than 1200 km of coastline. Resultant spatially patchy loss of coral cover under widespread and high levels of bleaching and cyclonic activity, suggests a degree of resilience for WA coral communities. However, the spatial extent of bleaching casts some doubt over hypotheses suggesting that future impacts to coral reefs under forecast warming regimes may in part be mitigated by southern thermal refugia.

  2. Exploring the Symbiodinium rare biosphere provides evidence for symbiont switching in reef-building corals.

    Science.gov (United States)

    Boulotte, Nadine M; Dalton, Steven J; Carroll, Andrew G; Harrison, Peter L; Putnam, Hollie M; Peplow, Lesa M; van Oppen, Madeleine Jh

    2016-11-01

    Reef-building corals possess a range of acclimatisation and adaptation mechanisms to respond to seawater temperature increases. In some corals, thermal tolerance increases through community composition changes of their dinoflagellate endosymbionts (Symbiodinium spp.), but this mechanism is believed to be limited to the Symbiodinium types already present in the coral tissue acquired during early life stages. Compelling evidence for symbiont switching, that is, the acquisition of novel Symbiodinium types from the environment, by adult coral colonies, is currently lacking. Using deep sequencing analysis of Symbiodinium rDNA internal transcribed spacer 2 (ITS2) PCR amplicons from two pocilloporid coral species, we show evidence consistent with de novo acquisition of Symbiodinium types from the environment by adult corals following two consecutive bleaching events. Most of these newly detected symbionts remained in the rare biosphere (background types occurring below 1% relative abundance), but one novel type reached a relative abundance of ~33%. Two de novo acquired Symbiodinium types belong to the thermally resistant clade D, suggesting that this switching may have been driven by consecutive thermal bleaching events. Our results are particularly important given the maternal mode of Symbiodinium transmission in the study species, which generally results in high symbiont specificity. These findings will cause a paradigm shift in our understanding of coral-Symbiodinium symbiosis flexibility and mechanisms of environmental acclimatisation in corals.

  3. Detecting sedimentation impacts to coral reefs resulting from dredging the Port of Miami, Florida USA.

    Science.gov (United States)

    Miller, Margaret W; Karazsia, Jocelyn; Groves, Carolyn E; Griffin, Sean; Moore, Tom; Wilber, Pace; Gregg, Kurtis

    2016-01-01

    The federal channel at Port of Miami, Florida, USA, was dredged between late 2013 and early 2015 to widen and deepen the channel. Due to the limited spatial extent of impact-assessment monitoring associated with the project, the extent of the dredging impacts on surrounding coral reefs has not been well quantified. Previously published remote sensing analyses, as well as agency and anecdotal reports suggest the most severe and largest area of sedimentation occurred on a coral reef feature referred to as the Inner Reef, particularly in the sector north of the channel. A confounding regional warm-water mass bleaching event followed by a coral disease outbreak during this same time frame made the assessment of dredging-related impacts to coral reefs adjacent to the federal channel difficult but still feasible. The current study sought to better understand the sedimentation impacts that occurred in the coral reef environment surrounding Port of Miami, to distinguish those impacts from other regional events or disturbances, and provide supplemental information on impact assessment that will inform discussions on compensatory mitigation requirements. To this end, in-water field assessments conducted after the completion of dredging and a time series analysis of tagged corals photographed pre-, during, and post-dredging, are used to discern dredging-related sedimentation impacts for the Inner Reef north. Results indicate increased sediment accumulation, severe in certain times and places, and an associated biological response (e.g., higher prevalence of partial mortality of corals) extended up to 700 m from the channel, whereas project-associated monitoring was limited to 50 m from the channel. These results can contribute to more realistic prediction of areas of indirect effect from dredging projects needed to accurately evaluate proposed projects and design appropriate compliance monitoring. Dredging projects near valuable and sensitive habitats subject to local and

  4. Detecting sedimentation impacts to coral reefs resulting from dredging the Port of Miami, Florida USA

    Directory of Open Access Journals (Sweden)

    Margaret W. Miller

    2016-11-01

    Full Text Available The federal channel at Port of Miami, Florida, USA, was dredged between late 2013 and early 2015 to widen and deepen the channel. Due to the limited spatial extent of impact-assessment monitoring associated with the project, the extent of the dredging impacts on surrounding coral reefs has not been well quantified. Previously published remote sensing analyses, as well as agency and anecdotal reports suggest the most severe and largest area of sedimentation occurred on a coral reef feature referred to as the Inner Reef, particularly in the sector north of the channel. A confounding regional warm-water mass bleaching event followed by a coral disease outbreak during this same time frame made the assessment of dredging-related impacts to coral reefs adjacent to the federal channel difficult but still feasible. The current study sought to better understand the sedimentation impacts that occurred in the coral reef environment surrounding Port of Miami, to distinguish those impacts from other regional events or disturbances, and provide supplemental information on impact assessment that will inform discussions on compensatory mitigation requirements. To this end, in-water field assessments conducted after the completion of dredging and a time series analysis of tagged corals photographed pre-, during, and post-dredging, are used to discern dredging-related sedimentation impacts for the Inner Reef north. Results indicate increased sediment accumulation, severe in certain times and places, and an associated biological response (e.g., higher prevalence of partial mortality of corals extended up to 700 m from the channel, whereas project-associated monitoring was limited to 50 m from the channel. These results can contribute to more realistic prediction of areas of indirect effect from dredging projects needed to accurately evaluate proposed projects and design appropriate compliance monitoring. Dredging projects near valuable and sensitive habitats

  5. Towed-Diver Observations in the Main Hawaiian Islands to Assess the Mass Coral Bleaching Event from 2015-11-03 to 2015-11-18 (NCEI Accession 0157624)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A team from the Pacific Islands Fisheries Science Center (PIFSC), Coral Reef Ecosystem Program (CREP) deployed on a two-week research cruise in November 2015 to...

  6. Benthic Images from Towed-Diver Surveys in the Main Hawaiian Islands to Assess the Mass Coral Bleaching Event from 2015-11-03 to 2015-11-18 (NCEI Accession 0157611)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A team from the Pacific Islands Fisheries Science Center (PIFSC), Coral Reef Ecosystem Program (CREP) deployed on a two-week research cruise in November 2015 to...

  7. Climate Change in the Seychelles: Implications for Water and Coral Reefs

    Energy Technology Data Exchange (ETDEWEB)

    Payet, Rolph; Agricole, Wills [National Meteorological Services Mahe (Seychelles). Div. of Policy, Planning and Services

    2006-06-15

    The Seychelles is a small island state in the western Indian Ocean that is vulnerable to the effects of climate change. This vulnerability led the Intergovernmental Panel on Climate Change (IPCC) in 2001 to express concern over the potential economic and social consequences that may be faced by small island states. Small island states should be prepared to adapt to such changes, especially in view of their dependence on natural resources, such as water and coral reefs, to meet basic human welfare needs. Analysis of long-term data for precipitation, air temperature, and sea-surface temperature indicated that changes are already observable in the Seychelles. The increase in dry spells that resulted in drought conditions in 1999 and the 1998 mass coral bleaching are indicative of the events that are likely to occur under future climate change. Pre-IPCC Third Assessment Report scenarios and the new SRES scenarios are compared for changes in precipitation and air surface temperature for the Seychelles. These intercomparisons indicate that the IS92 scenarios project a much warmer and wetter climate for the Seychelles than do the SRES scenarios. However, a wetter climate does not imply readily available water, but rather longer dry spells with more intense precipitation events. These observations will likely place enormous pressures on water-resources management in the Seychelles. Similarly, sea-surface temperature increases predicted by the HADCm{sup 3} model will likely trigger repeated coral-bleaching episodes, with possible coral extinctions within the Seychelles region by 2040. The cover of many coral reefs around the Seychelles have already changed, and the protection of coral-resilient areas is a critical adaptive option.

  8. Specializing on vulnerable habitat: Acropora selectivity among damselfish recruits and the risk of bleaching-induced habitat loss

    Science.gov (United States)

    Bonin, M. C.

    2012-03-01

    Coral reef habitats are increasingly being degraded and destroyed by a range of disturbances, most notably climate-induced coral bleaching. Habitat specialists, particularly those associated with susceptible coral species, are clearly among the most vulnerable to population decline or extinction. However, the degree of specialization on coral microhabitats is still unclear for one of the most ubiquitous, abundant and well studied of coral reef fish families—the damselfishes (Pomacentridae). Using high taxonomic resolution surveys of microhabitat use and availability, this study provides the first species-level description of patterns of Acropora selectivity among recruits of 10 damselfish species in order to determine their vulnerability to habitat degradation. In addition, surveys of the bleaching susceptibility of 16 branching coral species revealed which preferred recruitment microhabitats are at highest risk of decline as a result of chronic coral bleaching. Four species (i.e., Chrysiptera parasema, Pomacentrus moluccensis, Dascyllus melanurus and Chromis retrofasciata) were identified as highly vulnerable because they used only branching hard corals as recruitment habitat and primarily associated with only 2-4 coral species. The bleaching surveys revealed that five species of Acropora were highly susceptible to bleaching, with more than 50% of colonies either severely bleached or already dead. These highly susceptible corals included two of the preferred microhabitats of the specialist C. parasema and represented a significant proportion of its total recruitment microhabitat. In contrast, highly susceptible corals were rarely used by another specialist, P. moluccensis, suggesting that this species faces a lower risk of bleaching-induced habitat loss compared to C. parasema. As degradation to coral reef habitats continues, specialists will increasingly be forced to use alternative recruitment microhabitats, and this is likely to reduce population

  9. Wave Dissipation on Low- to Super-Energy Coral Reefs

    Science.gov (United States)

    Harris, D. L.

    2016-02-01

    Coral reefs are valuable, complex and bio-diverse ecosystems and are also known to be one of the most effective barriers to swell events in coastal environments. Previous research has found coral reefs to be remarkably efficient in removing most of the wave energy during the initial breaking and transformation on the reef flats. The rate of dissipation is so rapid that coral reefs have been referred to as rougher than any known coastal barrier. The dissipation of wave energy across reef flats is crucial in maintaining the relatively low-energy conditions in the back reef and lagoonal environments providing vital protection to adjacent beach or coastal regions from cyclone and storm events. A shift in the regulation of wave energy by reef flats could have catastrophic consequences ecologically, socially, and economically. This study examined the dissipation of wave energy during two swell events in Tahiti and Moorea, French Polyesia. Field sites were chosen in varying degrees of exposure and geomorphology from low-energy protected sites (Tiahura, Moorea) to super-energy sites (Teahupo'o, Tahiti). Waves were measured during two moderate to large swell events in cross reef transects using short-term high-resolution pressure transducers. Wave conditions were found to be similar in all back reef locations despite the very different wave exposure at each reef site. However, wave conditions on the reef flats were different and mirrored the variation in wave exposure with depth over the reef flat the primary regulator of reef flat wave height. These results indicate that coral reef flats evolve morphodynamically with the wave climate, which creates coral reef geomorphologies capable of dissipating wave energy that results in similar back reef wave conditions regardless of the offshore wave climate.

  10. A population genetic assessment of coral recovery on highly disturbed reefs of the Keppel Island archipelago in the southern Great Barrier Reef

    Directory of Open Access Journals (Sweden)

    Madeleine J.H. van Oppen

    2015-07-01

    isolation and contributes to the conservation value of the archipelago. The lack of evidence for genetic erosion, in combination with our observation that the North Keppel Island population samples collected in 2002 and 2008, respectively, exhibited a pairwise genetic distance of zero, supports previous published work indicating that, following bleaching, Acropora corals in the Keppel Islands predominantly recover from regrowth of small amounts of remaining live tissue in apparently dead coral colonies. This is likely supplemented by recruitment of larvae from genetically similar, less disturbed populations at nearby reefs, particularly following extreme flood events.

  11. Vaal Reefs

    International Nuclear Information System (INIS)

    Anon.

    1983-01-01

    Vaal Reefs Mine, the world's top gold producer with an output last quarter of 19,6 tons of gold, is to expand further with the building of an 120 000t/month run-of-mine mill at the new No 9 Shaft in the south area, linked with a carbon-in-pulp plant

  12. Regulation of apoptotic mediators reveals dynamic responses to thermal stress in the reef building coral Acropora millepora.

    Science.gov (United States)

    Pernice, Mathieu; Dunn, Simon R; Miard, Thomas; Dufour, Sylvie; Dove, Sophie; Hoegh-Guldberg, Ove

    2011-01-24

    Mass coral bleaching is increasing in scale and frequency across the world's coral reefs and is being driven primarily by increased levels of thermal stress arising from global warming. In order to understand the impacts of projected climate change upon corals reefs, it is important to elucidate the underlying cellular mechanisms that operate during coral bleaching and subsequent mortality. In this respect, increased apoptotic cell death activity is an important cellular process that is associated with the breakdown of the mutualistic symbiosis between the cnidarian host and their dinoflagellate symbionts. The PRESENT study reports the impacts of different stressors (colchicine and heat stress) on three phases of apoptosis: (i) the potential initiation by differential expression of Bcl-2 members, (ii) the execution of apoptotic events by activation of caspase 3-like proteases and (iii) and finally, the cell disposal indicated by DNA fragmentation in the reef building coral Acropora millepora. In corals incubated with colchicine, an increase in caspase 3-like activity and DNA fragmentation was associated with a relative down-regulation of Bcl-2, suggesting that the initiation of apoptosis may be mediated by the suppression of an anti-apoptotic mechanism. In contrast, in the early steps of heat stress, the induction of caspase-dependent apoptosis was related to a relative up-regulation of Bcl-2 consecutively followed by a delayed decrease in apoptosis activity. In the light of these results, we propose a model of heat stress in coral hosts whereby increasing temperatures engage activation of caspase 3-dependent apoptosis in cells designated for termination, but also the onset of a delayed protective response involving overexpression of Bcl-2 in surviving cells. This mitigating response to thermal stress could conceivably be an important regulatory mechanism for cell survival in corals exposed to sudden environmental changes.

  13. Regulation of apoptotic mediators reveals dynamic responses to thermal stress in the reef building coral Acropora millepora.

    Directory of Open Access Journals (Sweden)

    Mathieu Pernice

    2011-01-01

    Full Text Available Mass coral bleaching is increasing in scale and frequency across the world's coral reefs and is being driven primarily by increased levels of thermal stress arising from global warming. In order to understand the impacts of projected climate change upon corals reefs, it is important to elucidate the underlying cellular mechanisms that operate during coral bleaching and subsequent mortality. In this respect, increased apoptotic cell death activity is an important cellular process that is associated with the breakdown of the mutualistic symbiosis between the cnidarian host and their dinoflagellate symbionts.The PRESENT study reports the impacts of different stressors (colchicine and heat stress on three phases of apoptosis: (i the potential initiation by differential expression of Bcl-2 members, (ii the execution of apoptotic events by activation of caspase 3-like proteases and (iii and finally, the cell disposal indicated by DNA fragmentation in the reef building coral Acropora millepora. In corals incubated with colchicine, an increase in caspase 3-like activity and DNA fragmentation was associated with a relative down-regulation of Bcl-2, suggesting that the initiation of apoptosis may be mediated by the suppression of an anti-apoptotic mechanism. In contrast, in the early steps of heat stress, the induction of caspase-dependent apoptosis was related to a relative up-regulation of Bcl-2 consecutively followed by a delayed decrease in apoptosis activity.In the light of these results, we propose a model of heat stress in coral hosts whereby increasing temperatures engage activation of caspase 3-dependent apoptosis in cells designated for termination, but also the onset of a delayed protective response involving overexpression of Bcl-2 in surviving cells. This mitigating response to thermal stress could conceivably be an important regulatory mechanism for cell survival in corals exposed to sudden environmental changes.

  14. Herbivory versus corallivory: are parrotfish good or bad for Caribbean coral reefs?

    Science.gov (United States)

    Mumby, Peter J.

    2009-09-01

    With coral cover in decline on many Caribbean reefs, any process of coral mortality is of potential concern. While sparisomid parrotfishes are major grazers of Caribbean reefs and help control algal blooms, the fact that they also undertake corallivory has prompted some to question the rationale for their conservation. Here the weight of evidence for beneficial effects of parrotfishes, in terms of reducing algal cover and facilitating demographic processes in corals, and the deleterious effects of parrotfishes in terms of causing coral mortality and chronic stress, are reviewed. While elevated parrotfish density will likely increase the predation rate upon juvenile corals, the net effect appears to be positive in enhancing coral recruitment through removal of macroalgal competitors. Parrotfish corallivory can cause modest partial colony mortality in the most intensively grazed species of Montastraea but the generation and healing of bite scars appear to be in near equilibrium, even when coral cover is low. Whole colony mortality in adult corals can lead to complete exclusion of some delicate, lagoonal species of Porites from forereef environments but is only reported for one reef species ( Porites astreoides), for one habitat (backreef), and with uncertain incidence (though likely zooxanthellae after bleaching events may be retarded. The balance of evidence to date finds strong support for the herbivory role of parrotfishes in facilitating coral recruitment, growth, and fecundity. In contrast, no net deleterious effects of corallivory have been reported for reef corals. Corallivory is unlikely to constrain overall coral cover but contraints upon dwindling populations of the Montastraea annularis species complex are feasible and the role of parrotfishes as a vector of coral disease requires evaluation. However, any assertion that conservation practices should guard against protecting corallivorous parrotfishes appears to be unwarranted at this stage.

  15. [Changes in fish communities of coral reefs at Sabana-Camagüey Archipelago, Cuba].

    Science.gov (United States)

    Claro, Rodolfo; Cantelar, Karel; Amargós, Fabián Pina; García-Arteaga, Juan P

    2007-06-01

    A comparison of fish community structure in the Sabana-Camagüey Archipelago (1988-1989 and 2000) using visual census surveys (eight belt transects 2x50 m in each site) suggests a notable decrease on species richness, and a two thirds reduction in fish density and biomass on coral reefs. This decrease in fish populations may be related to the alarming decrease of scleractinian coral cover, and an enormous proliferation of algae, which currently covers 70-80% of the hard substrate, impeding the recovery of corals and other benthic organisms. High coral mortalities occurred between the study periods, which correlate with the high temperatures caused by the ENSO events of 1995, 1997 and 1998. These events caused massive bleaching of corals and subsequent algae overgrowth. Evidence of nutrient enrichment from the inner lagoons and overfishing are also present. Collectively, these effects have provoked a marked degradation of reef habitats. These changes appear to have affected the availability of refuges and food for fishes, and may be constraining individual growth potential and population size.

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

    OpenAIRE

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

    2009-01-01

    Abstract 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 unde...

  17. Ten years after bleaching - facing the consequences of climate change in the Indian Ocean.CORDIO Status Report 2008.

    OpenAIRE

    Grimsditch, G.; Mwaura, J.; Kilonzo, J.; Amiyo, N.; Obura, D.

    2008-01-01

    When a coral bleaches, the obligate symbiosis between the coral polyp and the micro-algal zooxanthellae is disrupted and the zooxanthellae are expelled from the polyp. Although a bleached coral does not necessarily die, it is more vulnerable to disease, algal overgrowth, bioerosion and eventually mortality. Mass bleaching and mortality events in the last decade have prompted increased research into zooxanthellae, and it is possible that zooxanthellae population strategies affect a coral’s tol...

  18. Site-specific variation in gene expression from Symbiodinium spp. associated with offshore and inshore Porites astreoides in the lower Florida Keys is lost with bleaching and disease stress.

    Directory of Open Access Journals (Sweden)

    Briana Hauff Salas

    Full Text Available Scleractinian coral are experiencing unprecedented rates of mortality due to increases in sea surface temperatures in response to global climate change. Some coral species however, survive high temperature events due to a reduced susceptibility to bleaching. We investigated the relationship between bleaching susceptibility and expression of five metabolically related genes of Symbiodinium spp. from the coral Porites astreoides originating from an inshore and offshore reef in the Florida Keys. The acclimatization potential of Symbiodinium spp. to changing temperature regimes was also measured via a two-year reciprocal transplant between the sites. Offshore coral fragments displayed significantly higher expression in Symbiodinium spp. genes PCNA, SCP2, G3PDH, PCP and psaE than their inshore counterparts (p<0.05, a pattern consistent with increased bleaching susceptibility in offshore corals. Additionally, gene expression patterns in Symbiodinium spp. from site of origin were conserved throughout the two-year reciprocal transplant, indicating acclimatization did not occur within this multi-season time frame. Further, laboratory experiments were used to investigate the influence of acute high temperature (32°C for eight hours and disease (lipopolysaccharide of Serratia marcescens on the five metabolically related symbiont genes from the same offshore and inshore P. astreoides fragments. Gene expression did not differ between reef fragments, or as a consequence of acute exposure to heat or heat and disease, contrasting to results found in the field. Gene expression reported here indicates functional variation in populations of Symbiodinium spp. associated with P. astreoides in the Florida Keys, and is likely a result of localized adaptation. However, gene expression patterns observed in the lab imply that functional variation in zooxanthellae observed under conditions of chronic moderate stress is lost under the acute extreme conditions studied here.

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

    Science.gov (United States)

    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 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.

  20. Project O.R.B (Operation Reef Ball): Creating Artificial Reefs, Educating the Community

    Science.gov (United States)

    Phipps, A.

    2012-04-01

    The Project O.R.B. (Operation Reef Ball) team at South Plantation High School's Everglades Restoration & Environmental Science Magnet Program is trying to help our ailing south Florida coral reefs by constructing, deploying, and monitoring designed artificial reefs. Students partnered with the Reef Ball Foundation, local concrete companies, state parks, Girl Scouts, Sea Scouts, local universities and environmental agencies to construct concrete reef balls, each weighing approximately 500 lbs (227 kg). Students then deployed two artificial reefs consisting of over 30 concrete reef balls in two sites previously permitted for artificial reef deployment. One artificial reef was placed approximately 1.5 miles (2.4 km) offshore of Golden Beach in Miami-Dade County with the assistance of Florida Atlantic University and their research vessel. A twin reef was deployed at the mouth of the river in Oleta River State Park in Miami. Monitoring and maintenance of the sites is ongoing with semi-annual reports due to the Reef Ball Foundation and DERM (Department of Environmental Resource Management) of Miami-Dade County. A second goal of Project O.R.B. is aligned with the Florida Local Action Strategy, the Southeast Florida Coral Reef Initiative, and the U.S. Coral Reef Task Force, all of which point out the importance of awareness and education as key components to the health of our coral reefs. Project O.R.B. team members developed and published an activity book targeting elementary school students. Outreach events incorporate cascade learning where high school students teach elementary and middle school students about various aspects of coral reefs through interactive "edu-tainment" modules. Attendees learn about water sampling, salinity, beach erosion, surface runoff, water cycle, ocean zones, anatomy of coral, human impact on corals, and characteristics of a well-designed artificial reef. Middle school students snorkel on the artificial reef to witness first-hand the success

  1. The unnatural history of Kāne'ohe Bay: coral reef resilience in the face of centuries of anthropogenic impacts.

    Science.gov (United States)

    Bahr, Keisha D; Jokiel, Paul L; Toonen, Robert J

    2015-01-01

    ne'ohe Bay developed under estuarine conditions and thus have been subjected to multiple natural stresses. These include storm floods, a more extreme temperature range than more oceanic reefs, high rates of sedimentation, and exposure at extreme low tides. Deposition and degradation of organic materials carried into the bay from the watershed results in low pH conditions such that according to some ocean acidification projections the rich coral reefs in the bay should not exist. Increased global temperature due to anthropogenic fossil fuel emmisions is now impacting these reefs with the first "bleaching event" in 1996 and a second more severe event in 2014. The reefs of Kāne'ohe Bay have developed and persist under rather severe natural and anthropogenic perturbations. To date, these reefs have proved to be very resilient once the stressor has been removed. A major question remains to be answered concerning the limits of Kāne'ohe Bay reef resilience in the face of global climate change.

  2. The current status of coral reefs and their vulnerability to climate change and multiple human stresses in the Comoros Archipelago, Western Indian Ocean.

    Science.gov (United States)

    Cowburn, B; Samoilys, M A; Obura, D

    2018-05-31

    Coral bleaching and various human stressors have degraded the coral reefs of the Comoros Archipelago in the past 40 years and rising atmospheric CO 2 levels are predicted to further impact marine habitats. The condition of reefs in the Comoros is poorly known; using SCUBA based methods we surveyed reef condition and resilience to bleaching at sites in Grande Comore and Mohéli in 2010 and 2016. The condition of reefs was highly variable, with a range in live coral cover between 6% and 60% and target fishery species biomass between 20 and 500 kg per ha. The vulnerability assessment of reefs to future coral bleaching and their exposure to fishing, soil erosion and river pollution in Mohéli Marine Park found that offshore sites around the islets south of the island were least likely to be impacted by these negative pressures. The high variability in both reef condition and vulnerability across reefs in the Park lends itself to spatially explicit conservation actions. However, it is noteworthy that climate impacts to date appear moderate and that local human pressures are not having a major impact on components of reef health and recovery, suggesting these reefs are relatively resilient to the current anthropogenic stresses that they are experiencing. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Relationship between anthropogenic impacts and bleaching-associated tissue mortality of corals in Curaçao (Netherlands Antilles)

    NARCIS (Netherlands)

    Nagelkerken, I.

    2007-01-01

    Chronic anthropogenic impacts can have a negative effect on coral health and on coral energy budgets needed for regeneration of lesions. I therefore hypothesise that during massive bleaching events, the degree of corals showing bleaching-related tissue mortality is higher in areas subject to chronic

  4. THE IMPACT OF CDOM PHOTOBLEACHING ON UV ATTENUATION NEAR CORAL REEFS IN THE FLORIDA KEYS

    Science.gov (United States)

    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 coral reefs in the Florida Keys. Extended exposure to UV may contribute to coral bleaching episodes. C...

  5. Agents of coral mortality on reef formations of the Colombian Pacific

    Directory of Open Access Journals (Sweden)

    Raúl Navas-Camacho

    2010-05-01

    Full Text Available The National Monitoring System for Coral Reefs of Colombia (SIMAC monitors the impact of some of the most important agents of coral tissue loss (bleaching and/or disease in the Colombian Pacific coral formations since 1998. Physiological bleaching is among the main results of stress in the area. Signs of coral diseases resembling bacterial bleaching such as White Plague and White Band, were observed in Malpelo and Gorgona islands. Damage to the Pacific gorgonian Pacifigorgia spp., similar to those produced by Aspergillosis in Caribbean corals, was detected in Utría Bay. The presence of tumors in colonies of massive corals was also recorded. Even though coral diseases are globally widespread, their occurrence in American Pacific reefs has been poorly documented to date. Rev. Biol. Trop. 58 (Suppl. 1: 133-138. Epub 2010 May 01.

  6. Agents of coral mortality on reef formations of the Colombian Pacific.

    Science.gov (United States)

    Navas-Camacho, Raúl; Rodríguez-Ramírez, Alberto; Reyes-Nivia, María Catalina

    2010-05-01

    The National Monitoring System for Coral Reefs of Colombia (SIMAC) monitors the impact of some of the most important agents of coral tissue loss (bleaching and/or disease) in the Colombian Pacific coral formations since 1998. Physiological bleaching is among the main results of stress in the area. Signs of coral diseases resembling bacterial bleaching such as White Plague and White Band, were observed in Malpelo and Gorgona islands. Damage to the Pacific gorgonian Pacifigorgia spp., similar to those produced by Aspergillosis in Caribbean corals, was detected in Utria Bay. The presence of tumors in colonies of massive corals was also recorded. Even though coral diseases are globally widespread, their occurrence in American Pacific reefs has been poorly documented to date.

  7. The unnatural history of Kāne‘ohe Bay: coral reef resilience in the face of centuries of anthropogenic impacts

    Directory of Open Access Journals (Sweden)

    Keisha D. Bahr

    2015-05-01

    coral cover. The reefs of Kāneʻohe Bay developed under estuarine conditions and thus have been subjected to multiple natural stresses. These include storm floods, a more extreme temperature range than more oceanic reefs, high rates of sedimentation, and exposure at extreme low tides. Deposition and degradation of organic materials carried into the bay from the watershed results in low pH conditions such that according to some ocean acidification projections the rich coral reefs in the bay should not exist. Increased global temperature due to anthropogenic fossil fuel emmisions is now impacting these reefs with the first “bleaching event” in 1996 and a second more severe event in 2014. The reefs of Kāneʻohe Bay have developed and persist under rather severe natural and anthropogenic perturbations. To date, these reefs have proved to be very resilient once the stressor has been removed. A major question remains to be answered concerning the limits of Kāneʻohe Bay reef resilience in the face of global climate change.

  8. Study on Bleaching Technology of Cotton Fabric with Sodium Percarbonate

    OpenAIRE

    Li Zhi; Wang Yanling; Wang Zhichao

    2016-01-01

    Bleach cotton fabric with sodium percarbonate solution. Analyse of the effect of the concentration of sodium percarbonate solution, bleaching time, bleaching temperature and the light radiation on the bleaching effect of fabric.The result shows that increasing concentrations of percarbonate,increasing the bleaching time , raising the bleaching temperature and the UV irradiation may whiten the cotton fabric.The most suitable conditions for the bleaching process is concentration of sodium perca...

  9. Synergistic impacts of global warming on the resilience of coral reefs

    Science.gov (United States)

    Bozec, Yves-Marie; Mumby, Peter J.

    2015-01-01

    Recent epizootics have removed important functional species from Caribbean coral reefs and left communities vulnerable to alternative attractors. Global warming will impact reefs further through two mechanisms. A chronic mechanism reduces coral calcification, which can result in depressed somatic growth. An acute mechanism, coral bleaching, causes extreme mortality when sea temperatures become anomalously high. We ask how these two mechanisms interact in driving future reef state (coral cover) and resilience (the probability of a reef remaining within a coral attractor). We find that acute mechanisms have the greatest impact overall, but the nature of the interaction with chronic stress depends on the metric considered. Chronic and acute stress act additively on reef state but form a strong synergy when influencing resilience by intensifying a regime shift. Chronic stress increases the size of the algal basin of attraction (at the expense of the coral basin), whereas coral bleaching pushes the system closer to the algal attractor. Resilience can change faster—and earlier—than a change in reef state. Therefore, we caution against basing management solely on measures of reef state because a loss of resilience can go unnoticed for many years and then become disproportionately more difficult to restore.

  10. Patterns of Symbiodinium (Dinophyceae) diversity and assemblages among diverse hosts and the coral reef environment of Lizard Island, Australia

    KAUST Repository

    Ziegler, Maren

    2018-04-26

    Large-scale environmental disturbances may impact both partners in coral host-Symbiodinium systems. Elucidation of the assembly patterns in such complex and interdependent communities may enable better prediction of environmental impacts across coral reef ecosystems. In this study, we investigated how the community composition and diversity of dinoflagellate symbionts in the genus Symbiodinium were distributed among 12 host species from six taxonomic orders (Actinaria, Alcyonacea, Miliolida, Porifera, Rhizostoma, Scleractinia) and in the reef water and sediments at Lizard Island, Great Barrier Reef before the 3rd Global Coral Bleaching Event. 454 pyrosequencing of the ITS2 region of Symbiodinium yielded 83 Operational Taxonomic Units (OTUs) at a 97% similarity cut-off. Approximately half of the Symbiodinium OTUs from reef water or sediments were also present in symbio. OTUs belonged to six clades (A-D, F-G), but community structure was uneven. The two most abundant OTUs (100% matches to types C1 and A3) comprised 91% of reads and OTU C1 was shared by all species. However, sequence-based analysis of these dominant OTUs revealed host species-specificity, suggesting that genetic similarity cut-offs of Symbiodinium ITS2 data sets need careful evaluation. Of the less abundant OTUs, roughly half occurred at only one site or in one species and the background Symbiodinium communities were distinct between individual samples. We conclude that sampling multiple host taxa with differing life history traits will be critical to fully understand the symbiont diversity of a given system and to predict coral ecosystem responses to environmental change and disturbance considering the differential stress response of the taxa within. This article is protected by copyright. All rights reserved.

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

    KAUST Repository

    Hadaidi, Ghaida Ali Hassan

    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.

  12. Feedbacks Between Wave Energy And Declining Coral Reef Structure: Implications For Coastal Morphodynamics

    Science.gov (United States)

    Grady, A. E.; Jenkins, C. J.; Moore, L. J.; Potts, D. C.; Burgess, P. M.; Storlazzi, C. D.; Elias, E.; Reidenbach, M. A.

    2013-12-01

    The incident wave energy dissipated by the structural complexity and bottom roughness of coral reef ecosystems, and the carbonate sediment produced by framework-building corals, provide natural shoreline protection and nourishment, respectively. Globally, coral reef ecosystems are in decline as a result of ocean warming and acidification, which is exacerbated by chronic regional stressors such as pollution and disease. As a consequence of declining reef health, many reef ecosystems are experiencing reduced coral cover and shifts to dominance by macroalgae, resulting in a loss of rugosity and thus hydrodynamic roughness. As coral reef architecture is compromised and carbonate skeletons are eroded, wave energy dissipation and sediment transport patterns--along with the carbonate sediment budget of the coastal environment--may be altered. Using a Delft3D numerical model of the south-central Molokai, Hawaii, fringing reef, we simulate the effects of changing reef states on wave energy and sediment transport. To determine the temporally-varying effects of biotic and abiotic stressors such as storms and bleaching on the reef structure and carbonate production, we couple Delft3D with CarboLOT, a model that simulates growth and competition of carbonate-producing organisms. CarboLOT is driven by the Lotka-Volterra population ecology equations and niche suitability principles, and accesses the CarboKB database for region-specific, carbonate-producing species information on growth rates, reproduction patterns, habitat suitability, as well as organism geometries. Simulations assess how changing reef states--which alter carbonate sediment production and reef morphology and thus hydrodynamic roughness--impact wave attenuation and sediment transport gradients along reef-fronted beaches. Initial results suggest that along fringing reefs having characteristics similar to the Molokai fringing reef, projected sea level rise will likely outpace coral reef accretion, and the increased

  13. The continuing decline of coral reefs in Bahrain.

    Science.gov (United States)

    Burt, John A; Al-Khalifa, Khalifa; Khalaf, Ebtesam; Alshuwaikh, Bassem; Abdulwahab, Ahmed

    2013-07-30

    Historically coral reefs of Bahrain were among the most extensive in the southern basin of the Arabian Gulf. However, Bahrain's reefs have undergone significant decline in the last four decades as a result of large-scale coastal development and elevated sea surface temperature events. Here we quantitatively surveyed six sites including most major coral reef habitats around Bahrain and a reef located 72 km offshore. Fleshy and turf algae now dominate Bahrain's reefs (mean: 72% cover), and live coral cover is low (mean: 5.1%). Formerly dominant Acropora were not observed at any site. The offshore Bulthama reef had the highest coral cover (16.3%) and species richness (22 of the 23 species observed, 13 of which were exclusive to this site). All reefs for which recent and historical data are available show continued degradation, and it is unlikely that they will recover under continuing coastal development and projected climate change impacts. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Mark I McCormick

    2009-09-01

    Full Text Available 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.

  15. Future habitat suitability for coral reef ecosystems under global warming and ocean acidification.

    Science.gov (United States)

    Couce, Elena; Ridgwell, Andy; Hendy, Erica J

    2013-12-01

    Rising atmospheric CO2 concentrations are placing spatially divergent stresses on the world's tropical coral reefs through increasing ocean surface temperatures and ocean acidification. We show how these two stressors combine to alter the global habitat suitability for shallow coral reef ecosystems, using statistical Bioclimatic Envelope Models rather than basing projections on any a priori assumptions of physiological tolerances or fixed thresholds. We apply two different modeling approaches (Maximum Entropy and Boosted Regression Trees) with two levels of complexity (one a simplified and reduced environmental variable version of the other). Our models project a marked temperature-driven decline in habitat suitability for many of the most significant and bio-diverse tropical coral regions, particularly in the central Indo-Pacific. This is accompanied by a temperature-driven poleward range expansion of favorable conditions accelerating up to 40-70 km per decade by 2070. We find that ocean acidification is less influential for determining future habitat suitability than warming, and its deleterious effects are centered evenly in both hemispheres between 5° and 20° latitude. Contrary to expectations, the combined impact of ocean surface temperature rise and acidification leads to little, if any, degradation in future habitat suitability across much of the Atlantic and areas currently considered 'marginal' for tropical corals, such as the eastern Equatorial Pacific. These results are consistent with fossil evidence of range expansions during past warm periods. In addition, the simplified models are particularly sensitive to short-term temperature variations and their projections correlate well with reported locations of bleaching events. Our approach offers new insights into the relative impact of two global environmental pressures associated with rising atmospheric CO2 on potential future habitats, but greater understanding of past and current controls on coral

  16. Microtensile bond strength of enamel after bleaching.

    Science.gov (United States)

    Lago, Andrea Dias Neves; Garone-Netto, Narciso

    2013-01-01

    To evaluate the bond strength of a composite resin to the bovine enamel bleached with 35% hydrogen peroxide. It was used an etching-and-rinse adhesive system employed immediately, 7 and 14 days after the bleaching. Twenty bovine teeth were randomly distributed into 4 groups (n = 5), 3 experimental and 1 control. G1: Unbleached + restoration 14 days after storage in artificial saliva (control); G2: Bleached + restoration immediately after bleaching; G3: Bleached + restoration 7 days after bleaching; G4: Bleached + restoration 14 days after bleaching. Their buccal enamel surfaces were flattened, and a 25 mm² (5 × 5 mm) area from each one of these regions was outlined so as to standardize the experimental region. Universal hybrid composite resin Filtek™Z350 was inserted into four layers of 1 mm each and photo-activated. The bond strength was quantitatively evaluated by a microtensile test (1.0 mm/min) 24 h after the restorative procedures. The failure mode was assessed through scanning electron microscopy (SEM). There was a significant reduction in the bond strength of the restored teeth immediately after the bleaching (G2). There were no significant differences in enamel bond strength between groups G1, G3, and G4. There was a predominance of adhesive and mixed (cohesive + adhesive) failure in all groups. The 7-day-period after the end of the bleaching with 35% hydrogen peroxide was enough to achieve the appropriate values of bond strength to the enamel.

  17. Body image disturbance and skin bleaching.

    Science.gov (United States)

    Charles, Christopher A D; McLean, Shua-Kym

    2017-11-01

    This study looks at body image disturbance among Jamaicans who bleach their skin. The hypothesis states that there is a positive relationship between skin bleaching and body image disturbance. The study used a convenience sample of 160 participants with a skin bleaching group (n = 80) and a non-bleaching comparison group (n = 80). The instrument included demographic questions, the body image disturbance questionnaire (BIDQ), and questions about skin bleaching. The results of a t-test revealed that the skin bleaching group (M = 1.5255, SD = 0.42169) was not significantly different from the non-bleaching group (M = 1.4938, SD = 0.74217) in terms of body image disturbance, t(158) = 0.333, p = .740. The participants who bleached did not suffer from body image disturbance. Self-reports revealed that they bleached to acquire beauty, attract a partner, elude the police, and market skin bleaching products. The practice was fashionable and popular and it made some participants feel good, while others were fans of a popular musical artiste who bleached his skin. The majority of participants bleached because of the perceived personal, social, and entrepreneurial benefits of the practice and not because they suffered emotional distress, anxiety, and functional impairment because of their skin colour. However, there was some level of BID among the minority of participants who argued that they bleached because they wanted to be pretty so they were emotionally distressed about there body image and experienced functional impairment. © 2017 The British Psychological Society.

  18. Marine protected areas increase resilience among coral reef communities.

    Science.gov (United States)

    Mellin, Camille; Aaron MacNeil, M; Cheal, Alistair J; Emslie, Michael J; Julian Caley, M

    2016-06-01

    With marine biodiversity declining globally at accelerating rates, maximising the effectiveness of conservation has become a key goal for local, national and international regulators. Marine protected areas (MPAs) have been widely advocated for conserving and managing marine biodiversity yet, despite extensive research, their benefits for conserving non-target species and wider ecosystem functions remain unclear. Here, we demonstrate that MPAs can increase the resilience of coral reef communities to natural disturbances, including coral bleaching, coral diseases, Acanthaster planci outbreaks and storms. Using a 20-year time series from Australia's Great Barrier Reef, we show that within MPAs, (1) reef community composition was 21-38% more stable; (2) the magnitude of disturbance impacts was 30% lower and (3) subsequent recovery was 20% faster that in adjacent unprotected habitats. Our results demonstrate that MPAs can increase the resilience of marine communities to natural disturbance possibly through herbivory, trophic cascades and portfolio effects. © 2016 John Wiley & Sons Ltd/CNRS.

  19. Microhardness of demineralized enamel following home bleaching and laser-assisted in office bleaching

    Science.gov (United States)

    Ghanbarzadeh, Majid; Akbari, Majid; Hamzei, Haniye

    2015-01-01

    Background There is little data regarding the effect of tooth whitening on microhardness of white spot lesions. This study was conducted to investigate the effect of home-bleaching and laser-assisted in-office bleaching on microhardness of demineralized enamel. Material and Methods Forty bovine incisors were selected and immersed in a demineralizing solution for 12 weeks to induce white spot lesions. Enamel blocks were prepared and randomly assigned to two groups of 20 each. The first group underwent home bleaching with 15% carbamide peroxide which was applied for 8 hours a day over a period of 15 days. In the second group, in-office bleaching was performed by 40% hydrogen peroxide and powered by irradiation from an 810 nm gallium-aluminum-arsenide (GaAlAs) diode laser (CW, 2W). This process was performed for 3 sessions every seven days, in 15 days. The specimens were stored in Fusayama Meyer artificial saliva during the experiment. Surface microhardness was assessed before and after the bleaching therapies in both groups. Results Microhardness decreased significantly following both home bleaching and laser-assisted in-office bleaching (pTooth whitening through home bleaching or laser-assisted in-office bleaching can result in a significant reduction in microhardness of white spot lesions. Therefore, it is suggested to take protective measures on bleached demineralized enamel. Key words:White spot lesion, bleaching, laser, microhardness, demineralized enamel, home bleaching, in-office bleaching. PMID:26330939

  20. Challenges for Managing Fisheries on Diverse Coral Reefs

    Directory of Open Access Journals (Sweden)

    Douglas Fenner

    2012-03-01

    Full Text Available Widespread coral reef decline has included the decline of reef fish populations, and the subsistence and artisanal fisheries that depend on them. Overfishing and destructive fishing have been identified as the greatest local threats to coral reefs, but the greatest future threats are acidification and increases in mass coral bleaching caused by global warming. Some reefs have shifted from dominance by corals to macroalgae, in what are called “phase shifts”. Depletion of herbivores including fishes has been identified as a contributor to such phase shifts, though nutrients are also involved in complex interactions with herbivory and competition. The depletion of herbivorous fishes implies a reduction of the resilience of coral reefs to the looming threat of mass coral mortality from bleaching, since mass coral deaths are likely to be followed by mass macroalgal blooms on the newly exposed dead substrates. Conventional stock assessment of each fish species would be the preferred option for understanding the status of the reef fishes, but this is far too expensive to be practical because of the high diversity of the fishery and poverty where most reefs are located. In addition, stock assessment models and fisheries in general assume density dependent populations, but a key prediction that stocks recover from fishing is not always confirmed. Catch Per Unit Effort (CPUE has far too many weaknesses to be a useful method. The ratio of catch to stock and the proportion of catch that is mature depend on fish catch data, and are heavily biased toward stocks that are in good condition and incapable of finding species that are in the worst condition. Near-pristine reefs give us a reality check about just how much we have lost. Common fisheries management tools that control effort or catch are often prohibitively difficult to enforce for most coral reefs except in developed countries. Ecosystem-based management requires management of impacts of fishing

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Orit Nir

    Full Text Available 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.

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

    Science.gov (United States)

    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 O 2 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. Coral reefs - Specialized ecosystems

    Digital Repository Service at National Institute of Oceanography (India)

    Wafar, M.V.M.

    This paper discusses briefly some aspects that characterize and differentiate coral reef ecosystems from other tropical marine ecosystems. A brief account on the resources that are extractable from coral reefs, their susceptibility to natural...

  5. NMFS Reef Survey Forms

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Reef Environmental Survey Project (REEF) mission to educate and enlist divers in the conservation of marine habitats is accomplished primarily through its Fish...

  6. Efficacy of cold light bleaching using different bleaching times and their effects on human enamel.

    Science.gov (United States)

    Wang, Wei; Zhu, Yuhe; Li, Jiajia; Liao, Susan; Ai, Hongjun

    2013-01-01

    This study investigated the efficacy of cold light bleaching using different bleaching times and the effects thereof on tooth enamel. Before and after bleaching, stained tooth specimens were subjected to visual and instrumental colorimetric assessments using Vita Shade Guide and spectrophotometric shade matching. Enamel surface alterations were examined using scanning electron microscopy (SEM) to analyze surface morphology, surface microhardness (SMH) measurement to determine changes in mechanical properties, and X-ray diffraction (XRD) to characterize post-bleaching enamel composition. Cold light bleaching successfully improved tooth color, with optimal efficacy when bleaching time was beyond 10 min. Significant differences in surface morphology were observed among the different bleaching times, but no significant differences were observed for enamel composition and surface microhardness among the different bleaching times. Results of this study revealed an association between the bleaching time of cold light bleaching and its whitening efficacy. Together with the results on enamel surface changes, this study provided positive evidence to support cold light bleaching as an in-office bleaching treatment.

  7. Radiation coloration and bleaching of glass

    International Nuclear Information System (INIS)

    Treadaway, M.J.; Passenheim, B.C.; Kitterer, B.D.; Schall, P.

    1976-01-01

    The results of an investigation of the bleaching of radiation-induced darkening in ten Schott optical glasses is presented. Measurements were made at several temperatures from 160K to 340K for times from 5 msec to 500 hours after exposure. The theory of processes distributed in activation energies has been used to formulate a model which explains the time and temperature dependence of the bleaching. Analysis of the bleaching results in terms of this model has yielded the activation energy distributions and ''frequency factors'' which govern the bleaching for each material

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

    Science.gov (United States)

    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.

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

    OpenAIRE

    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 u...

  10. Biochemical methane potential of kraft bleaching effluent and codigestion with other in-mill streams

    DEFF Research Database (Denmark)

    Fitamo, Temesgen Mathewos; Dahl, Olli; Master, Emma

    2016-01-01

    and in combination: total bleaching effluent, alkaline bleaching effluent, kraft evaporator condensate, and chemithermomechanical pulping effluent. The total bleaching effluent, consisting of the chlorine dioxide bleaching and alkaline bleaching effluents, exhibited the highest potential for organic matter...

  11. In vitro penetration of bleaching agents into the pulp chamber

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Valera, M C; Mancini, M N G

    2004-01-01

    To investigate pulp chamber penetration of bleaching agents in teeth following restorative procedures.......To investigate pulp chamber penetration of bleaching agents in teeth following restorative procedures....

  12. Origins and Implications of a Primary Crown-of-Thorns Starfish Outbreak in the Southern Great Barrier Reef

    Directory of Open Access Journals (Sweden)

    Ian Miller

    2015-01-01

    Full Text Available The crown-of-thorns starfish (COTS is a major predator of hard corals. Repeated COTS outbreaks in the Cairns and Central sections of the Great Barrier Reef (GBR have been responsible for greater declines in coral cover than any other type of disturbance, including cyclones, disease, and coral bleaching. Knowledge of the precise timing and location of primary outbreaks could reveal the initial drivers of outbreaks and so could indicate possible management measures. In the central GBR, COTS outbreaks appear to follow major flooding events, but despite many years of observations, no primary outbreak has ever been unequivocally identified in the central and northern GBR. Here we locate a primary outbreak of COTS on the southern GBR which is not correlated with flooding. Instead it appears to have been the result of a combination of life history traits of COTS and prevailing oceanographic conditions. The hydrodynamic setting implies that the outbreak could disperse larvae to other reefs in the region.

  13. Satellite-Observed Black Water Events off Southwest Florida: Implications for Coral Reef Health in the Florida Keys National Marine Sanctuary

    OpenAIRE

    Zhao, Jun; Hu, Chuanmin; Lapointe, Brian; Melo, Nelson; Johns, Elizabeth; Smith, Ryan

    2013-01-01

    A “black water” event, as observed from satellites, occurred off southwest Florida in 2012. Satellite observations suggested that the event started in early January and ended in mid-April 2012. The black water patch formed off central west Florida and advected southward towards Florida Bay and the Florida Keys with the shelf circulation, which was confirmed by satellite-tracked surface drifter trajectories. Compared with a previous black water event in 2002, the 2012 event was weaker in terms...

  14. THE BLEACHING SYNDROME: MANIFESTATION OF A POST ...

    African Journals Online (AJOL)

    User

    universal and extends to the Americas and elsewhere impacted by colonial influences. Without exception .... "They say we should stop bleaching because of skin cancer and skin disease. ... Kenya, activists moved to have a ban put on the sale of skin bleaching creams. In agreement .... socioeconomic standing. Furthermore ...

  15. A comparison between the 2010 and 2016 El-Ninō induced coral bleaching in the Indonesian waters

    Science.gov (United States)

    Wouthuyzen, Sam; Abrar, M.; Lorwens, J.

    2018-02-01

    Severe coral bleaching events are always associated with El-Ninō phenomenon which caused a rise in ocean temperature between 1-2°C and that they potentially kill the corals worldwide. There were at least four severe coral bleaching events occurred in the Indonesian waters. This study aims to compare the coral bleaching events of the 2010 and 2016 and their impact on corals in Indonesian waters. Long-term (2002-2017) remotely sensed night time sea surface temperature (SST) data acquired from Aqua MODIS Satellite were used in the analysis. Here, we calculated the mean monthly maximum (MMM)of SST as SST in normal condition in which coral can adapt to temperature; the differences between high SST in each pixel during coral bleaching events of the 2010/2016 and MMM SST, called hot spot (HS); and how long has HS occupied a certain water body, called degree of heating weeks (DHW, °C-week) and then mapped it. Results show that the MMM SST for the Indonesian waters is 29.1°C. Both bleaching events of 2010 and 2016 started and finished in the same periods of Mar-Jun and they nearly have the same pattern, but bleaching magnitude of the 2016 was stronger than 2010 with the mean SST about 0.4°C higher in May-June. The percentage of impacted areas of strong thermal stress on corals of Alert-1 plus Alert-2 status was higher in 2016 (39.4%) compared to 2010 (31.3%). Coral bleaching events in the 2010 and 2016 spread in almost all Indonesian waters and relatively occurred in the same places but with small variation in the bleaching sites that was caused by the strength/weakness of El-Ninō and upwelling phenomenon as well as the role of Indonesian through flow (ITF).

  16. BLEACHING IN VITAL TEETH: A LITERARY REVIEW

    Directory of Open Access Journals (Sweden)

    Felipe Fagundes Soares

    2007-12-01

    Full Text Available Tooth bleaching technique has presented a significant evolution, promoting higher satisfaction and comfort to the patients. Therefore, the aim of this study was to present the bleaching agents and the techniques, discussing advantages and disadvantages of each one, and the effect of these agents in the oral environment. The main agents used in the bleaching technique are the hydrogen peroxide and the carbamide peroxide, promoting the bleaching effect through oxidation of organic compounds. The application of these agents can be made at home or at a doctor office. During treatment, it may occur some adverse effects, such as tooth sensibility, increasing of dental porosity, and some interactions with the restorative material. However, these adverse effects can be eliminated or controlled when the treatment is executed under professional orientation. When the bleaching technique is well indicated and correctly conducted, it is associated with significantly positive results.

  17. Side effects of external tooth bleaching

    DEFF Research Database (Denmark)

    Bruzell, E.M.; Pallesen, Ulla; Thoresen, N.R.

    2013-01-01

    Objective The study was performed to assess the risk of at-home and in-office bleaching procedures, and to recognise potential predictors for side effects. Design Multi-centre, questionnaire-based prospective study with follow-ups at around 14 days and around one year post-treatment. Setting...... General practices and university clinics during the years 2007‑2009 in Scandinavia. Subjects Patients with tooth bleaching as part of the treatment plan. Results The prevalence of experienced tooth sensitivity at first follow-up was independent of bleaching procedure (at-home = 50.3% [n = 143]; in...... attributed to the bleaching treatment in the at-home and in-office groups, respectively. Predictors for side effects were tooth sensitivity, surface loss and gingivitis when observed at inclusion. Treatment-related predictors were bleaching concentration and contact between tray and gingiva. Conclusions...

  18. Microtensile bond strength of enamel after bleaching

    Directory of Open Access Journals (Sweden)

    Andréa Dias Neves Lago

    2013-01-01

    Full Text Available Objective: To evaluate the bond strength of a composite resin to the bovine enamel bleached with 35% hydrogen peroxide. It was used an etching-and-rinse adhesive system employed immediately, 7 and 14 days after the bleaching. Materials and Methods: Twenty bovine teeth were randomly distributed into 4 groups (n = 5, 3 experimental and 1 control. G1: Unbleached + restoration 14 days after storage in artificial saliva (control; G2: Bleached + restoration immediately after bleaching; G3: Bleached + restoration 7 days after bleaching; G4: Bleached + restoration 14 days after bleaching. Their buccal enamel surfaces were flattened, and a 25 mm² (5 × 5 mm area from each one of these regions was outlined so as to standardize the experimental region. Universal hybrid composite resin Filtek™Z350 was inserted into four layers of 1 mm each and photo-activated. The bond strength was quantitatively evaluated by a microtensile test (1.0 mm/min 24 h after the restorative procedures. The failure mode was assessed through scanning electron microscopy (SEM. Results: There was a significant reduction in the bond strength of the restored teeth immediately after the bleaching (G2. There were no significant differences in enamel bond strength between groups G1, G3, and G4. There was a predominance of adhesive and mixed (cohesive + adhesive failure in all groups. Conclusion: The 7-day-period after the end of the bleaching with 35% hydrogen peroxide was enough to achieve the appropriate values of bond strength to the enamel.

  19. The future of coral reefs in the US Virgin Islands: is Acropora palmata more likely to recover than Montastraea annularis complex?

    Science.gov (United States)

    Rogers, Caroline S.; Muller, Erinn; Spitzack, Tony; Miller, Jeff

    2008-01-01

    Coral diseases have played a major role in the degradation of coral reefs in the Caribbean, including those in the US Virgin Islands (USVI). In 2005, bleaching affected reefs throughout the Caribbean, and was especially severe on USVI reefs. Some corals 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 coral cover. Montastraea annularis, the most abundant coral, was disproportionately affected, and decreased in relative abundance. The threatened species Acropora palmata bleached for the first time on record in the USVI but suffered less bleaching 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 bleaching and disease.

  20. Impact of upwelling events on the sea water carbonate chemistry and dissolved oxygen concentration in the Gulf of Papagayo (Culebra Bay, Costa Rica: Implications for coral reefs

    Directory of Open Access Journals (Sweden)

    Tim Rixen

    2012-04-01

    Full Text Available The Gulf of Papagayo, Pacific coast of Costa Rica, is one of the three seasonal upwelling areas of Mesoamerica. In April 2009, a 29-hour experiment was carried out at the pier of the Marina Papagayo, Culebra Bay. We determined sea surface temperature (SST, dissolved oxygen concentration, salinity, pH, and the partial pressure of CO2 (pCO2. The aragonite saturation state (Ωa as well as the other parameters of the marine carbonate system such as the total dissolved inorganic carbon (DIC and the total alkalinity (TA were calculated based on the measured pH and the pCO2. The entrainment of subsurface waters raised the pCO2 up to 645 µatm. SSTs, dissolved oxygen concentrations decreased form 26.4 to 23.7°C and from 228 to 144 µmol l-1. Ωa dropped down to values of 2.1. Although these changes are assumed to reduce the coral growth, the main reef building coral species within the region (Pocillopora spp. and Pavona clavus reveal growth rates exceeding those measured at other sites in the eastern tropical Pacific. This implies that the negative impact of upwelling on coral growth might be overcompensated by an enhanced energy supply caused by the high density of food and nutrients and more favorable condition for coral growth during the non-upwelling season.

  1. Multiple Stressors and Ecological Complexity Require A New Approach to Coral Reef Research

    Directory of Open Access Journals (Sweden)

    Linwood Hagan Pendleton

    2016-03-01

    Full Text Available Ocean acidification, climate change, and other environmental stressors threaten coral reef ecosystems and the people who depend upon them. New science reveals that these multiple stressors interact and may affect a multitude of physiological and ecological processes in complex ways. The interaction of multiple stressors and ecological complexity may mean that the negative effects on coral reef ecosystems will happen sooner and be more severe than previously thought. Yet, most research on the effects of global change on coral reefs focus on one or few stressors and pathways or outcomes (e.g. bleaching. Based on a critical review of the literature, we call for a regionally targeted strategy of mesocosm-level research that addresses this complexity and provides more realistic projections about coral reef impacts in the face of global environmental change. We believe similar approaches are needed for other ecosystems that face global environmental change.

  2. Coral reefs and the World Bank.

    Science.gov (United States)

    Hatziolos, M

    1997-01-01

    The World Bank¿s involvement in coral reef conservation is part of a larger effort to promote the sound management of coastal and marine resources. This involves three major thrusts: partnerships, investments, networks and knowledge. As an initial partner and early supporter of the International Coral Reef Initiative (ICRI), the Bank serves as the executive planning committee of ICRI. In partnership with the World Conservation Union and the Great Barrier Reef Marine Park Authority, the Bank promotes the efforts towards the establishment and maintenance of a globally representative system of marine protected areas. In addition, the Bank invested over $120 million in coral reef rehabilitation and protection programs in several countries. Furthermore, the Bank developed a ¿Knowledge Bank¿ that would market ideas and knowledge to its clients along with investment projects. This aimed to put the best global knowledge on environmentally sustainable development in the hands of its staff and clients. During the celebration of 1997, as the International Year of the Reef, the Bank planned to cosponsor an associated event that would highlight the significance of coral reefs and encourage immediate action to halt their degradation to conserve this unique ecosystem.

  3. 40 CFR 63.445 - Standards for the bleaching system.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards for the bleaching system. 63... Standards for Hazardous Air Pollutants from the Pulp and Paper Industry § 63.445 Standards for the bleaching system. (a) Each bleaching system that does not use any chlorine or chlorinated compounds for bleaching...

  4. Events

    Directory of Open Access Journals (Sweden)

    Igor V. Karyakin

    2016-02-01

    Full Text Available The 9th ARRCN Symposium 2015 was held during 21st–25th October 2015 at the Novotel Hotel, Chumphon, Thailand, one of the most favored travel destinations in Asia. The 10th ARRCN Symposium 2017 will be held during October 2017 in the Davao, Philippines. International Symposium on the Montagu's Harrier (Circus pygargus «The Montagu's Harrier in Europe. Status. Threats. Protection», organized by the environmental organization «Landesbund für Vogelschutz in Bayern e.V.» (LBV was held on November 20-22, 2015 in Germany. The location of this event was the city of Wurzburg in Bavaria.

  5. [Assessment of tooth bleaching efficacy with spectrophotometer].

    Science.gov (United States)

    Zhu, Wenhao; Liu, Chang; Pan, Jie

    2014-06-01

    To analyze the changes in CIE L*, a*, and b* at cervical, body, and incisal sites after tooth bleaching by using a spectrophotometer. Sixty-seven intact and healthy maxillary central incisors were in-vestigated. These incisors were darker than A3 according to the Vita Classical shade guide. The CIE tooth shade parameters L*, a*, and b* were simultaneously recorded at three tooth areas (cervical, body, and incisal) with a spectrophotometer before and after tooth bleaching (35%H2O2 coordinating with Beyond whitening accelerator irradiating). The shade dif-ferential (DeltaE) was calculated. ANOVA, paired t-test, and Pearson correlation analysis were used for data analysis. The efficacy rates of tooth bleaching were satisfactory, with 86.6%, 86.6%, and 85.1% in the cervical, body, and incisal sites, respectively. The average values of DeltaE were 5.09, 4.44, and 4.40 in the cervical, body, and incisal sites. Tooth bleaching significantly increased L* and significantly decreased a* and b* in all tooth areas (P spectrophotometer could objectively evaluate the whitening effect of tooth bleaching at the different tooth sites. The tooth bleaching system (35%H202 coordinating with Beyond whitening accelerator irradiating) exerts powerful bleaching actions in most of the tooth areas investigated. The order of tooth bleaching effectiveness is cervicalbody>incisal. Yellow coloration is decreased mainly at the cervical site, and brightness was increased mostly at theincisal site. The effectiveness of tooth bleaching increases as the baseline b* value increases.

  6. The distribution and abundance of reef-associated predatory fishes on the Great Barrier Reef

    Science.gov (United States)

    Emslie, Michael J.; Cheal, Alistair J.; Logan, Murray

    2017-09-01

    Predatory fishes are important components of coral-reef ecosystems of the Great Barrier Reef (GBR) through both the ecological functions they perform and their high value to recreational and commercial fisheries, estimated at 30 million in 2014. However, management of GBR predatory fish populations is hampered by a lack of knowledge of their distribution and abundance, aside from that of the highly targeted coral trout ( Plectropomus spp. and Variola spp.). Furthermore, there is little information on how these fishes respond to environmental stressors such as coral bleaching, outbreaks of coral-feeding starfishes ( Acanthaster planci) and storms, which limits adaptive management of their populations as the frequency or severity of such natural disturbances increases under climate change. Here, we document the distribution and abundance of 48 species of reef-associated predatory fishes and assess their vulnerability to a range of natural disturbances. There were clear differences in predatory fish assemblages across the continental shelf, but many species were widespread, with few species restricted to either inshore or offshore waters. There was weak latitudinal structure with only a few species restricted to either the northern or southern GBR. On the whole, predatory fishes were surprisingly resistant to the effects of disturbance, with few clear changes in abundance or species richness following 66 documented disturbances of varying magnitudes.

  7. Estimating the effect of multiple environmental stressors on coral bleaching and mortality.

    Directory of Open Access Journals (Sweden)

    Paul D Welle

    Full Text Available Coral cover has been declining in recent decades due to increased temperatures and environmental stressors. However, the extent to which different stressors contribute both individually and in concert to bleaching and mortality is still very uncertain. We develop and use a novel regression approach, using non-linear parametric models that control for unobserved time invariant effects to estimate the effects on coral bleaching and mortality due to temperature, solar radiation, depth, hurricanes and anthropogenic stressors using historical data from a large bleaching event in 2005 across the Caribbean. Two separate models are created, one to predict coral bleaching, and the other to predict near-term mortality. A large ensemble of supporting data is assembled to control for omitted variable bias and improve fit, and a significant improvement in fit is observed from univariate linear regression based on temperature alone. The results suggest that climate stressors (temperature and radiation far outweighed direct anthropogenic stressors (using distance from shore and nearby human population density as a proxy for such stressors in driving coral health outcomes during the 2005 event. Indeed, temperature was found to play a role ~4 times greater in both the bleaching and mortality response than population density across their observed ranges. The empirical models tested in this study have large advantages over ordinary-least squares-they offer unbiased estimates for censored data, correct for spatial correlation, and are capable of handling more complex relationships between dependent and independent variables. The models offer a framework for preparing for future warming events and climate change; guiding monitoring and attribution of other bleaching and mortality events regionally and around the globe; and informing adaptive management and conservation efforts.

  8. Estimating the effect of multiple environmental stressors on coral bleaching and mortality.

    Science.gov (United States)

    Welle, Paul D; Small, Mitchell J; Doney, Scott C; Azevedo, Inês L

    2017-01-01

    Coral cover has been declining in recent decades due to increased temperatures and environmental stressors. However, the extent to which different stressors contribute both individually and in concert to bleaching and mortality is still very uncertain. We develop and use a novel regression approach, using non-linear parametric models that control for unobserved time invariant effects to estimate the effects on coral bleaching and mortality due to temperature, solar radiation, depth, hurricanes and anthropogenic stressors using historical data from a large bleaching event in 2005 across the Caribbean. Two separate models are created, one to predict coral bleaching, and the other to predict near-term mortality. A large ensemble of supporting data is assembled to control for omitted variable bias and improve fit, and a significant improvement in fit is observed from univariate linear regression based on temperature alone. The results suggest that climate stressors (temperature and radiation) far outweighed direct anthropogenic stressors (using distance from shore and nearby human population density as a proxy for such stressors) in driving coral health outcomes during the 2005 event. Indeed, temperature was found to play a role ~4 times greater in both the bleaching and mortality response than population density across their observed ranges. The empirical models tested in this study have large advantages over ordinary-least squares-they offer unbiased estimates for censored data, correct for spatial correlation, and are capable of handling more complex relationships between dependent and independent variables. The models offer a framework for preparing for future warming events and climate change; guiding monitoring and attribution of other bleaching and mortality events regionally and around the globe; and informing adaptive management and conservation efforts.

  9. Mill Designed Bio bleaching Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Institute of Paper Science Technology

    2004-01-30

    A key finding of this research program was that Laccase Mediator Systems (LMS) treatments on high-kappa kraft could be successfully accomplished providing substantial delignification (i.e., > 50%) without detrimental impact on viscosity and significantly improved yield properties. The efficiency of the LMS was evident since most of the lignin from the pulp was removed in less than one hour at 45 degrees C. Of the mediators investigated, violuric acid was the most effective vis-a-vis delignification. A comparative study between oxygen delignification and violuric acid revealed that under relatively mild conditions, a single or a double LMS{sub VA} treatment is comparable to a single or a double O stage. Of great notability was the retention of end viscosity of LMS{sub VA} treated pulps with respect to the end viscosity of oxygen treated pulps. These pulps could then be bleached to full brightness values employing conventional ECF bleaching technologies and the final pulp physical properties were equal and/or better than those bleached in a conventional ECF manner employing an aggressively O or OO stage initially. Spectral analyses of residual lignins isolated after LMS treated high-kappa kraft pulps revealed that similar to HBT, VA and NHA preferentially attack phenolic lignin moieties. In addition, a substantial decrease in aliphatic hydroxyl groups was also noted, suggesting side chain oxidation. In all cases, an increase in carboxylic acid was observed. Of notable importance was the different selectivity of NHA, VA and HBT towards lignin functional groups, despite the common N-OH moiety. C-5 condensed phenolic lignin groups were overall resistant to an LMS{sub NHA, HBT} treatments but to a lesser extent to an LMS{sub VA}. The inactiveness of these condensed lignin moieties was not observed when low-kappa kraft pulps were biobleached, suggesting that the LMS chemistry is influenced by the extent of delignification. We have also demonstrated that the current

  10. Observations of infragravity motions for reef fringed islands and atolls

    Science.gov (United States)

    Becker, J. M.; Merrifield, M. A.; Ford, M.

    2012-12-01

    The frequency of flooding events that affect low lying islands and atolls in the Pacific is expected to increase under current sea level rise projections. Infragravity (IG) motions, with periods ranging from approximately 25 to 400 seconds, are an important component of wave driven flooding events for reef fringed islands and atolls. The IG variability during wave events is analyzed and interpreted dynamically from pressure and current observations at four cross-reef transects in the North Pacific Ocean that include sites in the Republic of the Marshall Islands and Guam. The IG motions are shown to depend upon the spectral properties of the incident wave forcing and reef flat characteristics that include reef flat length (ranging from 100m to 450m at the four sites) and total water level due to setup and tides. A small inundation event at one of the sites is shown to occur due to large shoreline infragravity energy.

  11. Artificial Reefs in Motion: Legacy of changes and degradation at the Redbird Reef Site

    Science.gov (United States)

    Trembanis, A. C.; DuVal, C.; Peter, B.

    2016-12-01

    Artificial reefs are used for a variety of purposes at sites throughout the U.S. and around the globe, yet little, if any, long-term monitoring has been conducted with the goal of understanding inter-annual changes to the emplaced structures. Throughout the U.S. Mid-Atlantic region, several programs utilized retired subway cars as disposal structures to form artificial reefs. One such site, known as site 11, or "Redbird Reef", is located off the coast of Delaware and was at one time home to 997 former NYC subway cars. Opportunistic sonar surveys at the site have been conducted between 2008 and 2016 providing one of the most extensive and repeated mapping studies for this type of reef. Previous studies conducted by our group at the site have focused on understanding wave orbital ripple dynamics and scour patterns. In this present study, we analyze the changes apparent at the site itself, focused on the storm-response dynamics of the subway cars. Results have shown that Superstorm Sandy in 2012 produced dramatic changes to the reef structures resulting in the total or partial destruction of eight subway cars within a small (.45 x .2km) portion of the reef site. Winter Storm Jonas in 2016 resulted in the destruction of fewer cars, but rotated a previously static 47m long Navy barge nearly 60 degrees. Once destroyed or collapsed by waves the subway cars go from providing positive structural relief and thus beneficial habitat above the surrounding seabed to being reduced to scattered low relief marine debris. A once popular consideration for reef material, the event and inter-annual decay of subway cars as observed at the Redbird reef provides both a stark indication of the power of storm dynamics on the inner-shelf and a cautionary tale with regards to the selection of seabed reef material.

  12. Climate change, global warming and coral reefs: modelling the effects of temperature.

    Science.gov (United States)

    Crabbe, M James C

    2008-10-01

    Climate change and global warming have severe consequences for the survival of scleractinian (reef-building) corals and their associated ecosystems. This review summarizes recent literature on the influence of temperature on coral growth, coral bleaching, and modelling the effects of high temperature on corals. Satellite-based sea surface temperature (SST) and coral bleaching information available on the internet is an important tool in monitoring and modelling coral responses to temperature. Within the narrow temperature range for coral growth, corals 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 coral reefs.

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

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

    2017-01-01

    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. - Highlights: • Undersupply with dissolved inorganic phosphate causes coral bleaching. • Ultrastructural biomarkers in algal symbionts identify nutrient stress in reef corals. • Uric acid crystals in zooxanthellae identify high N:P ratios in the water column. • Nitrate enrichment of the water causes phosphate deficiency in Symbiodinium. • Coral symbionts tolerate nitrogen limitation better than phosphorus limitation.

  15. Don't bleach chaotic data

    International Nuclear Information System (INIS)

    Theiler, J.; Eubank, S.

    1993-01-01

    A common first step in time series signal analysis involves digitally filtering the data to remove linear correlations. The residual data is spectrally white (it is ''bleached''), but in principle retains the nonlinear structure of the original time series. It is well known that simple linear autocorrelation can give rise to spurious results in algorithms for estimating nonlinear invariants, such as fractal dimension and Lyapunov exponents. In theory, bleached data avoids these pitfalls. But in practice, bleaching obscures the underlying deterministic structure of a low-dimensional chaotic process. This appears to be a property of the chaos itself, since nonchaotic data are not similarly affected. The adverse effects of bleaching are demonstrated in a series of numerical experiments on known chaotic data. Some theoretical aspects are also discussed

  16. Transcriptomic responses to heat stress and bleaching in the elkhorn coral Acropora palmata

    KAUST Repository

    DeSalvo, MK

    2010-03-08

    The emergence of genomic tools for reef-building corals and symbiotic anemones comes at a time when alarming losses in coral cover are being observed worldwide. These tools hold great promise in elucidating novel and unforeseen cellular processes underlying the successful mutualism between corals and their dinoflagellate endosymbionts Symbiodinium spp. Since thermal stress triggers a breakdown in the symbiosis (coral bleaching), measuring the transcriptomic response to thermal stress-induced bleaching offers an extraordinary view of cellular processes that are specific to coral–algal symbioses. In the present study, we utilized a cDNA microarray containing 2059 genes of the threatened Caribbean elkhorn coral Acropora palmata to identify genes that are differentially expressed upon thermal stress. Fragments from replicate colonies were exposed to elevated temperature for 2 d, and samples were frozen for microarray analysis after 24 and 48 h. Totals of 204 and 104 genes were differentially expressed in samples that were collected 1 and 2 d after thermal stress, respectively. Analysis of the differentially expressed genes indicates a cellular stress response in A. palmata involving (1) growth arrest, (2) chaperone activity, (3) nucleic acid stabilization and repair, and (4) removal of damaged macromolecules. Other differentially expressed processes include sensory perception, metabolite transfer between host and endosymbiont, nitric oxide signaling, and modifications to the actin cytoskeleton and extracellular matrix. The results are compared with those from a previous coral microarray study of thermal stress in Montastraea faveolata, and point to an overall evolutionary conserved bleaching response in scleractinian corals.

  17. Dimethylsulphoniopropionate (DMSP as an Indicator of Bleaching Tolerance in Scleractinian Corals

    Directory of Open Access Journals (Sweden)

    Graham B. Jones

    2015-06-01

    Full Text Available Thermal tolerance tests on Acropora millepora, a common Indo-Pacific hard coral, have shown that adult corals can acquire increased thermal tolerance by shuffling existing type C to type D Symbiodinium zooxanthellae when subjected to increased seawater temperatures. We report here dimethylsulphoniopropionate (DMSP concentrations in A. millepora and examine links between DMSP concentrations, zooxanthellae clade, and bleaching tolerance. DMSP analysis on native and transplanted corals from three locations in the Great Barrier Reef indicated that the lower thermal tolerance in type C zooxanthellae coincided with variable DMSP concentrations, whilst the more thermal tolerant type D zooxanthellae had more stable areal DMSP concentrations as seawater temperatures increased. Our results suggest this increased thermal tolerance in type D zooxanthellae may reflect the ability of these coral symbionts to conserve their antioxidant DMSP levels to relatively constant concentrations, enabling the coral to overcome the build-up of oxygen free radicals in the cytoplasm of A. millepora. A conceptual diagram illustrates how the antioxidants DMS (P participate in the bleaching process by scavenging oxygen free radicals and form DMSO, thus moderating coral bleaching and increasing thermotolerance.

  18. Transcriptomic responses to heat stress and bleaching in the elkhorn coral Acropora palmata

    KAUST Repository

    DeSalvo, MK; Sunagawa, S; Voolstra, Christian R.; Medina, M

    2010-01-01

    The emergence of genomic tools for reef-building corals and symbiotic anemones comes at a time when alarming losses in coral cover are being observed worldwide. These tools hold great promise in elucidating novel and unforeseen cellular processes underlying the successful mutualism between corals and their dinoflagellate endosymbionts Symbiodinium spp. Since thermal stress triggers a breakdown in the symbiosis (coral bleaching), measuring the transcriptomic response to thermal stress-induced bleaching offers an extraordinary view of cellular processes that are specific to coral–algal symbioses. In the present study, we utilized a cDNA microarray containing 2059 genes of the threatened Caribbean elkhorn coral Acropora palmata to identify genes that are differentially expressed upon thermal stress. Fragments from replicate colonies were exposed to elevated temperature for 2 d, and samples were frozen for microarray analysis after 24 and 48 h. Totals of 204 and 104 genes were differentially expressed in samples that were collected 1 and 2 d after thermal stress, respectively. Analysis of the differentially expressed genes indicates a cellular stress response in A. palmata involving (1) growth arrest, (2) chaperone activity, (3) nucleic acid stabilization and repair, and (4) removal of damaged macromolecules. Other differentially expressed processes include sensory perception, metabolite transfer between host and endosymbiont, nitric oxide signaling, and modifications to the actin cytoskeleton and extracellular matrix. The results are compared with those from a previous coral microarray study of thermal stress in Montastraea faveolata, and point to an overall evolutionary conserved bleaching response in scleractinian corals.

  19. Spatial and temporal patterns of mass bleaching of corals in the Anthropocene

    KAUST Repository

    Hughes, Terry P.; Anderson, Kristen D.; Connolly, Sean R.; Heron, Scott F.; Kerry, James T.; Lough, Janice M.; Baird, Andrew H.; Baum, Julia K.; Berumen, Michael L.; Bridge, Tom C.; Claar, Danielle C.; Eakin, C. Mark; Gilmour, James P.; Graham, Nicholas A. J.; Harrison, Hugo; Hobbs, Jean-Paul A.; Hoey, Andrew S.; Hoogenboom, Mia; Lowe, Ryan J.; McCulloch, Malcolm T.; Pandolfi, John M.; Pratchett, Morgan; Schoepf, Verena; Torda, Gergely; Wilson, Shaun K.

    2018-01-01

    from 1980 to 2016. The median return time between pairs of severe bleaching events has diminished steadily since 1980 and is now only 6 years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Nina

  20. Global and local threats to coral reef functioning and existence: review and predictions

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, C.R. [Australian Institute of Marine Sciences, Townsville, Qld. (Australia)

    1999-07-01

    Factors causing global degradation of coral reefs are examined briefly as a basis for predicting the likely consequences of increases in these factors. The earlier consensus was that widespread but localized damage from natural factors such as storms, and direct anthropogenic effects such as increased sedimentation, pollution and exploitation, posed the largest immediate threat to coral reefs. Now truly global factors associated with accelerating Global Climate Change are either damaging coral reefs or have the potential to inflict greater damage in the immediate future e.g. increases in coral bleaching and mortality, and reduction in coral calcification due to changes in sea-water chemistry with increasing carbon dioxide concentrations. Rises in sea level will probably disrupt human communities and their cultures by making coral cays uninhabitable, whereas coral reefs will sustain minimal damage from the rise in sea level. The short-term (decades) prognosis is that major reductions are almost certain in the extent and biodiversity of coral reefs, and severe disruptions to cultures and economies dependent on reef resources will occur. The long-term (centuries to millennia) prognosis is more encouraging because coral reefs have remarkable resilience to severe disruption and will probably show this resilience in the future when climate changes either stabilize or reverse.

  1. Impact of upwelling events on the sea water carbonate chemistry and dissolved oxygen concentration in the Gulf of Papagayo (Culebra Bay, Costa Rica: Implications for coral reefs

    Directory of Open Access Journals (Sweden)

    Tim Rixen

    2012-04-01

    Full Text Available The Gulf of Papagayo, Pacific coast of Costa Rica, is one of the three seasonal upwelling areas of Mesoamerica. In April 2009, a 29-hour experiment was carried out at the pier of the Marina Papagayo, Culebra Bay. We determined sea surface temperature (SST, dissolved oxygen concentration, salinity, pH, and the partial pressure of CO2 (pCO2. The aragonite saturation state (Ωa as well as the other parameters of the marine carbonate system such as the total dissolved inorganic carbon (DIC and the total alkalinity (TA were calculated based on the measured pH and the pCO2. The entrainment of subsurface waters raised the pCO2 up to 645 µatm. SSTs, dissolved oxygen concentrations decreased form 26.4 to 23.7°C and from 228 to 144 µmol l-1. Ωa dropped down to values of 2.1. Although these changes are assumed to reduce the coral growth, the main reef building coral species within the region (Pocillopora spp. and Pavona clavus reveal growth rates exceeding those measured at other sites in the eastern tropical Pacific. This implies that the negative impact of upwelling on coral growth might be overcompensated by an enhanced energy supply caused by the high density of food and nutrients and more favorable condition for coral growth during the non-upwelling season.El Golfo de Papagayo, costa Pacífica de Costa Rica, es una de las tres regiones de afloramiento estacional de Mesoamérica. Las características físicas y químicas del agua que aflora no habían sido estudiadas. Durante 29 horas en Abril 2009, se estudiaron la temperatura superficial del mar (TSM, la concentración de oxígeno disuelto, salinidad, pH y la presión parcial de CO2 (pCO2, en la Marina Papagayo, Bahía Culebra. Con base en las mediciones de pH y pCO2 se calculó el estado de saturación de la aragonita (Ω y otros parámetros del sistema de carbonatos como lo es el carbono orgánico disuelto (COD y la alcalinidad total (AT. Los resultados indican que el arrastre por convecci

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

    Science.gov (United States)

    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. © 2015 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

  3. Antioxidant responses to heat and light stress differ with habitat in a common reef coral

    Science.gov (United States)

    Hawkins, Thomas D.; Krueger, Thomas; Wilkinson, Shaun P.; Fisher, Paul L.; Davy, Simon K.

    2015-12-01

    Coral bleaching—the stress-induced collapse of the coral- Symbiodinium symbiosis—is a significant driver of worldwide coral reef degradation. Yet, not all corals are equally susceptible to bleaching, 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 bleaching susceptibility in the reef coral Stylophora pistillata. Using slow heating (1 °C d-1) and altered irradiance, we induced bleaching 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 bleaching (loss of symbiont cells), as well as in host enzymatic antioxidant activity [specifically, superoxide dismutase and catalase (CAT)]. However, among the coral fragments that bleached, most did so without displaying any evidence of a host enzymatic antioxidant response. For example, both deep and shallow corals 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 coral enzymatic antioxidants can vary significantly depending on habitat, and, in terms of determining bleaching susceptibility, our results suggest a significant role for the host's differential

  4. Impacts of Artificial Reefs on Surrounding Ecosystems

    Science.gov (United States)

    Manoukian, Sarine

    aggregations associated with Senigallia reef based on the analysis of multibeam backscatter data in the water column is also explored. The settlement of the reefs and any terrain change are investigated over time providing a useful description of the local hydrodynamics and geological processes. All the artificial structures (made up by water-based concrete for Senigallia reef and mainly steel for St. Petersburg Beach reef) are identified and those showing substantial horizontal and/or vertical movements are analyzed in detail. Most artificial modules of Senigallia reef are not intact and scour signatures are well depicted around them, indicating reversals of the local current. This is due to both the wind pattern and to the quite close arrangement of the reef units that tend to deflect the bottom flow. As regards to the St. Petersburg Beach reef, all the man-made steel units are still in their upright position. Only a large barge shows a gradual collapse of its south side, and presents well-developed scouring at its east-northeast side, indicating dominant bottom flow from west-southwest to east-northeast. While an overall seafloor depth shallowing of about 0.30 m from down-current deposits was observed for Senigallia reef, an overall deepening of about 0.08 m due to scour was observed at the St. Petersburg Beach reef. Based on the backscatter data interpretation, surficial sediments are coarser in the vicinities of both artificial reefs than corresponding surrounding sediments. Scouring reveals this coarser layer underneath the prevalent mud sediment at Senigallia reef, and the predominant silt sediment at St. Petersburg Beach reef. In the ten years of Senigalia reef study, large-scale variations between clay and silt appear to be directly linked to large flood events that have occurred just prior to the change. As regards the water column investigation, acoustic backscatter from fish aggregations gives detailed information on their morphology and spatial distribution. In

  5. Occurrence of 1 ka-old corals on an uplifted reef terrace in west Luzon, Philippines: Implications for a prehistoric extreme wave event in the South China Sea region

    Science.gov (United States)

    Ramos, Noelynna T.; Maxwell, Kathrine V.; Tsutsumi, Hiroyuki; Chou, Yu-Chen; Duan, Fucai; Shen, Chuan-Chou; Satake, Kenji

    2017-12-01

    Recent 230Th dating of fossil corals in west Luzon has provided new insights on the emergence of late Quaternary marine terraces that fringe west Luzon Island facing the Manila Trench. Apart from regional sea level changes, accumulated uplift from aseismic and seismic processes may have influenced the emergence of sea level indicators such as coral terraces and notches. Varied elevations of middle-to-late Holocene coral terraces along the west Luzon coasts reveal the differential uplift that is probably associated with the movement of local onland faults or upper-plate structures across the Manila Trench forearc basin. In Badoc Island, offshore west of Luzon mainland, we found notably young fossil corals, dated at 945.1 ± 4.6 years BP and 903.1 ± 3.9 years BP, on top of a 5-m-high reef platform. To constrain the mechanism of emergence or emplacement of these fossil corals, we use field geomorphic data and wave inundation models to constrain an extreme wave event that affected west Luzon about 1000 years ago. Our preliminary tectonic and tsunami models show that a megathrust rupture will likely lead to subsidence of a large part of the west Luzon coast, while permanent coastal uplift is attributed to an offshore upper-plate rupture in the northern Manila Trench forearc region. The modeled source fault ruptures and tsunami lead to a maximum wave height of more than 3 m and inundation distance as far as 2 km along the coasts of western and northern Luzon. While emplacement of coral boulders by an unusually strong typhoon is also likely, modeled storm surge heights along west Luzon do not exceed 2 m even with Typhoon Haiyan characteristics. Whether tsunami or unusually strong typhoon, the occurrence of a prehistoric extreme wave event in west Luzon remains an important issue in future studies of coastal hazards in the South China Sea region.

  6. Epigenome-associated phenotypic acclimatization to ocean acidification in a reef-building coral

    KAUST Repository

    Liew, Yi Jin; Zoccola, Didier; Li, Yong; Tambutté , Eric; Venn, Alexander A.; Michell, Craig; Cui, Guoxin; Deutekom, Eva S.; Kaandorp, Jaap A.; Voolstra, Christian R.; Forê t, Sylvain; Allemand, Denis; Tambutté , Sylvie; Aranda, Manuel

    2017-01-01

    Over the last century, the anthropogenic production of CO2 has led to warmer (+0.74 C) and more acidic (-0.1 pH) oceans, resulting in increasingly frequent and severe mass bleaching events worldwide that precipitate global coral reef decline. To mitigate this decline, proposals to augment the stress tolerance of corals through genetic and non-genetic means have been gaining traction. Work on model systems has shown that environmentally induced alterations in DNA methylation can lead to phenotypic acclimatization. While DNA methylation has been observed in corals, its potential role in phenotypic plasticity has not yet been described. Here, we show that, similar to findings in mice, DNA methylation significantly reduces spurious transcription in the Red Sea coral Stylophora pistillata, suggesting the evolutionary conservation of this essential mechanism in corals. Furthermore, we find that DNA methylation also reduces transcriptional noise by fine-tuning the expression of highly expressed genes. Analysis of DNA methylation patterns of corals subjected to long-term pH stress showed widespread changes in pathways regulating cell cycle and body size. Correspondingly, we found significant increases in cell and polyp sizes that resulted in more porous skeletons, supporting the maintenance of linear extension rates under conditions of reduced calcification. These findings suggest an epigenetic component in phenotypic acclimatization, providing corals with an additional mechanism to cope with climate change.

  7. Epigenome-associated phenotypic acclimatization to ocean acidification in a reef-building coral

    KAUST Repository

    Liew, Yi Jin

    2017-09-14

    Over the last century, the anthropogenic production of CO2 has led to warmer (+0.74 C) and more acidic (-0.1 pH) oceans, resulting in increasingly frequent and severe mass bleaching events worldwide that precipitate global coral reef decline. To mitigate this decline, proposals to augment the stress tolerance of corals through genetic and non-genetic means have been gaining traction. Work on model systems has shown that environmentally induced alterations in DNA methylation can lead to phenotypic acclimatization. While DNA methylation has been observed in corals, its potential role in phenotypic plasticity has not yet been described. Here, we show that, similar to findings in mice, DNA methylation significantly reduces spurious transcription in the Red Sea coral Stylophora pistillata, suggesting the evolutionary conservation of this essential mechanism in corals. Furthermore, we find that DNA methylation also reduces transcriptional noise by fine-tuning the expression of highly expressed genes. Analysis of DNA methylation patterns of corals subjected to long-term pH stress showed widespread changes in pathways regulating cell cycle and body size. Correspondingly, we found significant increases in cell and polyp sizes that resulted in more porous skeletons, supporting the maintenance of linear extension rates under conditions of reduced calcification. These findings suggest an epigenetic component in phenotypic acclimatization, providing corals with an additional mechanism to cope with climate change.

  8. Photosystem II heterogeneity of in hospite zooxanthellae in scleractinian corals exposed to bleaching conditions.

    Science.gov (United States)

    Hill, Ross; PeterJ, Ralph

    2006-01-01

    Increased ocean temperatures are thought to be triggering mass coral bleaching events around the world. The intracellular symbiotic zooxanthellae (genus Symbiodinium) are expelled from the coral host, which is believed to be a response to photosynthetic damage within these symbionts. Several sites of impact have been proposed, and here we probe the functional heterogeneity of Photosystem II (PSII) in three coral species exposed to bleaching conditions. As length of exposure to bleaching conditions (32 degrees C and 350 micromol photons m(-2) s(-1)) increased, the QA- reoxidation kinetics showed a rise in the proportion of inactive PSII centers (PSIIx), where QB was unable to accept electrons. PSIIx contributed up to 20% of the total PSII centers in Pocillopora damicornis, 35% in Acropora nobilis and 14% in Cyphastrea serailia. Changes in Fv/Fm and amplitude of the J step along fast induction curves were found to be highly dependent upon the proportion of PSIIx centers within the total pool of PSII reaction centers. Determination of PSII antenna size revealed that under control conditions in the three coral species up to 60% of PSII centers were lacking peripheral light-harvesting complexes (PSIIbeta). In P. damicornis, the proportion of PSIIbeta increased under bleaching conditions and this could be a photoprotective mechanism in response to excess light. The rapid increases in PSIIx and PSIIbeta observed in these corals under bleaching conditions indicates these physiological processes are involved in the initial photochemical damage to zooxanthellae.

  9. Variables and potential models for the bleaching of luminescence signals in fluvial environments

    Science.gov (United States)

    Gray, Harrison J.; Mahan, Shannon

    2015-01-01

    Luminescence dating of fluvial sediments rests on the assumption that sufficient sunlight is available to remove a previously obtained signal in a process deemed bleaching. However, luminescence signals obtained from sediment in the active channels of rivers often contain residual signals. This paper explores and attempts to build theoretical models for the bleaching of luminescence signals in fluvial settings. We present two models, one for sediment transported in an episodic manner, such as flood-driven washes in arid environments, and one for sediment transported in a continuous manner, such as in large continental scale rivers. The episodic flow model assumes that the majority of sediment is bleached while exposed to sunlight at the near surface between flood events and predicts a power-law decay in luminescence signal with downstream transport distance. The continuous flow model is developed by combining the Beer–Lambert law for the attenuation of light through a water column with a general-order kinetics equation to produce an equation with the form of a double negative exponential. The inflection point of this equation is compared with the sediment concentration from a Rouse profile to derive a non-dimensional number capable of assessing the likely extent of bleaching for a given set of luminescence and fluvial parameters. Although these models are theoretically based and not yet necessarily applicable to real-world fluvial systems, we introduce these ideas to stimulate discussion and encourage the development of comprehensive bleaching models with predictive power.

  10. Artificial reefs and reef restoration in the Laurentian Great Lakes

    Science.gov (United States)

    McLean, Matthew W.; Roseman, Edward; Pritt, Jeremy J.; Kennedy, Gregory W.; Manny, Bruce A.

    2015-01-01

    We reviewed the published literature to provide an inventory of Laurentian Great Lakes artificial reef projects and their purposes. We also sought to characterize physical and biological monitoring for artificial reef projects in the Great Lakes and determine the success of artificial reefs in meeting project objectives. We found records of 6 artificial reefs in Lake Erie, 8 in Lake Michigan, 3 in Lakes Huron and Ontario, and 2 in Lake Superior. We found 9 reefs in Great Lakes connecting channels and 6 reefs in Great Lakes tributaries. Objectives of artificial reef creation have included reducing impacts of currents and waves, providing safe harbors, improving sport-fishing opportunities, and enhancing/restoring fish spawning habitats. Most reefs in the lakes themselves were incidental (not created purposely for fish habitat) or built to improve local sport fishing, whereas reefs in tributaries and connecting channels were more frequently built to benefit fish spawning. Levels of assessment of reef performance varied; but long-term monitoring was uncommon as was assessment of physical attributes. Artificial reefs were often successful at attracting recreational species and spawning fish; however, population-level benefits of artificial reefs are unclear. Stressors such as sedimentation and bio-fouling can limit the effectiveness of artificial reefs as spawning enhancement tools. Our investigation underscores the need to develop standard protocols for monitoring the biological and physical attributes of artificial structures. Further, long-term monitoring is needed to assess the benefits of artificial reefs to fish populations and inform future artificial reef projects.

  11. Assessment of bleaching of K-feldspar grains

    International Nuclear Information System (INIS)

    Zhang Jiafu; Li Shenghua; Tso, M-Y.W.

    2001-01-01

    Based on the difference in the bleaching rate between IRSL and TL signals, a new method of assessing the bleaching of sedimentary feldspar is proposed. All measurements for De and the bleaching factor (normalized ratio of IRSL to TL) are carried out on the same grain. K-feldspar grains from two sediments, a marine and an alluvium, from Hong Kong were tested. Their bleaching factors indicate that bleaching of the marine sediment was not uniform, whereas the latter was relatively homogeneous. Furthermore, the relatively well-bleached grains in each sample were identified

  12. A dynamic bioenergetic model for coral-Symbiodinium symbioses and coral bleaching as an alternate stable state.

    Science.gov (United States)

    Cunning, Ross; Muller, Erik B; Gates, Ruth D; Nisbet, Roger M

    2017-10-27

    Coral reef ecosystems owe their ecological success - and vulnerability to climate change - to the symbiotic metabolism of corals and Symbiodinium spp. The urgency to understand and predict the stability and breakdown of these symbioses (i.e., coral 'bleaching') demands the development and application of theoretical tools. Here, we develop a dynamic bioenergetic model of coral-Symbiodinium symbioses that demonstrates realistic steady-state patterns in coral growth and symbiont abundance across gradients of light, nutrients, and feeding. Furthermore, by including a mechanistic treatment of photo-oxidative stress, the model displays dynamics of bleaching and recovery that can be explained as transitions between alternate stable states. These dynamics reveal that "healthy" and "bleached" states correspond broadly to nitrogen- and carbon-limitation in the system, with transitions between them occurring as integrated responses to multiple environmental factors. Indeed, a suite of complex emergent behaviors reproduced by the model (e.g., bleaching is exacerbated by nutrients and attenuated by feeding) suggests it captures many important attributes of the system; meanwhile, its modular framework and open source R code are designed to facilitate further problem-specific development. We see significant potential for this modeling framework to generate testable hypotheses and predict integrated, mechanistic responses of corals to environmental change, with important implications for understanding the performance and maintenance of symbiotic systems. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. Effectiveness of benthic foraminiferal and coral assemblages as water quality indicators on inshore reefs of the Great Barrier Reef, Australia

    Science.gov (United States)

    Uthicke, S.; Thompson, A.; Schaffelke, B.

    2010-03-01

    Although the debate about coral reef decline focuses on global disturbances (e.g., increasing temperatures and acidification), local stressors (nutrient runoff and overfishing) continue to affect reef health and resilience. The effectiveness of foraminiferal and hard-coral assemblages as indicators of changes in water quality was assessed on 27 inshore reefs along the Great Barrier Reef. Environmental variables (i.e., several water quality and sediment parameters) and the composition of both benthic foraminiferal and hard-coral assemblages differed significantly between four regions (Whitsunday, Burdekin, Fitzroy, and the Wet Tropics). Grain size and organic carbon and nitrogen content of sediments, and a composite water column parameter (based on turbidity and concentrations of particulate matter) explained a significant amount of variation in the data (tested by redundancy analyses) in both assemblages. Heterotrophic species of foraminifera were dominant in sediments with high organic content and in localities with low light availability, whereas symbiont-bearing mixotrophic species were dominant elsewhere. A similar suite of parameters explained 89% of the variation in the FORAM index (a Caribbean coral reef health indicator) and 61% in foraminiferal species richness. Coral richness was not related to environmental setting. Coral assemblages varied in response to environmental variables, but were strongly shaped by acute disturbances (e.g., cyclones, Acanthaster planci outbreaks, and bleaching), thus different coral assemblages may be found at sites with the same environmental conditions. Disturbances also affect foraminiferal assemblages, but they appeared to recover more rapidly than corals. Foraminiferal assemblages are effective bioindicators of turbidity/light regimes and organic enrichment of sediments on coral reefs.

  14. Exposure to elevated sea-surface temperatures below the bleaching threshold impairs coral recovery and regeneration following injury.

    Science.gov (United States)

    Bonesso, Joshua Louis; Leggat, William; Ainsworth, Tracy Danielle

    2017-01-01

    Elevated sea surface temperatures (SSTs) are linked to an increase in the frequency and severity of bleaching events due to temperatures exceeding corals' upper thermal limits. The temperatures at which a breakdown of the coral- Symbiodinium endosymbiosis (coral bleaching) occurs are referred to as the upper thermal limits for the coral species. This breakdown of the endosymbiosis results in a reduction of corals' nutritional uptake, growth, and tissue integrity. Periods of elevated sea surface temperature, thermal stress and coral bleaching are also linked to increased disease susceptibility and an increased frequency of storms which cause injury and physical damage to corals. Herein we aimed to determine the capacity of corals to regenerate and recover from injuries (removal of apical tips) sustained during periods of elevated sea surface temperatures which result in coral stress responses, but which do not result in coral bleaching (i.e., sub-bleaching thermal stress events). In this study, exposure of the species Acropora aspera to an elevated SST of 32 °C (2 °C below the bleaching threshold, 34 °C) was found to result in reduced fluorescence of green fluorescent protein (GFP), reduced skeletal calcification and a lack of branch regrowth at the site of injury, compared to corals maintained under ambient SST conditions (26 °C). Corals maintained under normal, ambient, sea surface temperatures expressed high GFP fluorescence at the injury site, underwent a rapid regeneration of the coral branch apical tip within 12 days of sustaining injury, and showed extensive regrowth of the coral skeleton. Taken together, our results have demonstrated that periods of sustained increased sea surface temperatures, below the corals' bleaching threshold but above long-term summertime averages, impair coral recovery from damage, regardless of the onset or occurrence of coral bleaching.

  15. Temperament and perception of tooth bleaching results

    Directory of Open Access Journals (Sweden)

    Katarzyna Mehr

    2016-09-01

    Full Text Available Background . The neurophysiological process of perceiving the results of tooth bleaching requires the correct interaction between the central nervous system and the organs of sight. Exaggerated beliefs concerning defective facial features may enhance inner attitudes about one’s own color of dentition, as well as a feeling of dissatisfaction with the degree of leaching. Objectives. The study aimed to assess the degree of the patient satisfaction with the results of tooth bleaching in relation to their temperament. Material and methods. There were 68 generally healthy volunteers, aged 28–38 years, with external discolorations of the teeth. They had never undergone dental bleaching and their frontal teeth did not have any fillings. After clinical evaluation and the completion of formalities, the patients were asked to fill in Strelau’s temperament questionnaire. Questionnaires and visual status were assessed three times by three doctors: before bleaching, and then 24 hours and two weeks after the home-bleaching operation, which was done with the use of Opalescence (Ultradent in uniform sequence. Results . There were practically no adverse side results, except a periodic dentin hypersensitivity that occurred periodically in 44 patients. The results of the visual assessment performed by the physicians did not differ. The questionnaire data showed that women were more critical of the results in relation to the expectations. Among elancholics, full satisfaction was declared by 41%, whereas among sanguine people, full satisfaction was obtained by 85%. Satisfaction with the aesthetic results was associated with bleaching by at least 4 degrees. Conclusions . Patients’ temperament affects their subjective evaluation of the effectiveness of tooth bleaching, which should be taken into consideration in the patient’s individual dental treatment plan.

  16. Bleaching and enamel surface interactions resulting from the use of highly-concentrated bleaching gels.

    Science.gov (United States)

    Grazioli, Guillermo; Valente, Lisia Lorea; Isolan, Cristina Pereira; Pinheiro, Helena Alves; Duarte, Camila Gonçalves; Münchow, Eliseu Aldrighi

    2018-03-01

    Tooth bleaching is considered a non-invasive treatment, although the use of highly-concentrated products may provoke increased surface roughness and enamel demineralization, as well as postoperative sensitivity. Thus, the aim of this study was to investigate whether hydrogen peroxide (H 2 O 2 ) concentration would affect tooth bleaching effectiveness and the enamel surface properties. Enamel/dentin bovine specimens (6 × 4 mm) were immersed in coffee solution for 7 days and evaluated with a spectrophotometer (Easyshade; baseline), using the CIEL * a * b * color parameters. Hardness was measured using a hardness tester. The specimens were randomly assigned into four groups: one negative control, in which the specimens were not bleached, but they were irradiated with a laser-light source (Whitening Lase II, DMC Equipments); and three groups using distinct H 2 O 2 concentration, namely LP15% (15% Lase Peroxide Lite), LP25% (25% Lase Peroxide Sensy), and LP35% (35% Lase Peroxide Sensy), all products from DMC. The bleached specimens were also irradiated with the laser-light source. After bleaching, all specimens were evaluated using scanning electron microscopy (SEM). pH kinetics and rate was monitored during bleaching. The data were analyzed using ANOVA and Tukey's test (p bleaching gels produced similar color change (p > 0.05). Concerning hardness, only the LP25% and LP35% significantly reduced hardness after bleaching; also, there was a progressive tendency for a greater percentage reduction in hardness with increased H 2 O 2 concentration of the gel (R 2  = 0.9973, p bleaching effectiveness, and may increase the possibility for alteration of enamel hardness, surface morphology, and acidity of the medium. When using H 2 O 2 -based bleaching agents, dental practitioners should choose for less concentrated gels, e.g., around the 15% level. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Coral reefs and eutrophication

    International Nuclear Information System (INIS)

    Stambler, N.

    1999-01-01

    Coral reefs are found in oligotrophic waters, which are poor in nutrients such as nitrogen, phosphate, and possibly iron. In spite of this, coral reefs exhibit high gross primary productivity rates. They thrive in oligotrophic conditions because of the symbiotic relationship between corals and dinoflagellate algae (zooxanthellae) embedded in the coral tissue. In their mutualistic symbiosis, the zooxanthellae contribute their photosynthetic capability as the basis for the metabolic energy of the whole association, and eventually of a great part of the entire reef ecosystem

  18. Color Recovery Effect of Different Bleaching Systems on a ...

    African Journals Online (AJOL)

    2017-12-05

    Dec 5, 2017 ... KEYWORDS: Composite resin, discoloration, home bleaching, laser activated bleaching, office ... hexametaphosphate, which protect the teeth surface from .... exposure, saliva and other fluids diluting the staining .... Penetration of the pulp ... dentin permeability of carbamide peroxide and hydrogen peroxide.

  19. Short communication: The influence of solids concentration and bleaching agent on bleaching efficacy and flavor of sweet whey powder.

    Science.gov (United States)

    Jervis, M G; Smith, T J; Drake, M A

    2015-04-01

    Recent studies have demonstrated the effect of bleaching conditions an