World's Coral Reefs Research Articles

Global human footprint on the linkage between biodiversity and ecosystem functioning in reef fishes.

Author SummaryThe increasing intensity of human disturbance worldwide is triggering unprecedented biodiversity losses, which is raising concerns over whether ecosystems will work and continue delivering goods and services to humanity. In contrast to previous experimental studies, which describe saturating relationships between ecosystem functioning and biodiversity, we show that in reef fish systems, functioning (as standing biomass) accelerates with the addition of new species. This non-saturating relationship implies unique contributions of species to the functioning of this ecosystem and indicates that the consequences of losing biodiversity are significantly greater than previously anticipated. We also demonstrate a negative effect of human density on reef fish functioning such that for the same number of people the loss of standing biomass is significantly larger in more diverse ecosystems. Unfortunately, human effects can arise through multiple stressors (such as fishing, coastal development, and land use) and are widespread and likely to worsen, as some 75% of the world's coral reefs are currently nearby human settlements and because almost all countries with coral reefs are expected to double their populations within the next 50 to 100 years. Our results call for both further investigation of the impact of biodiversity on ecosystem functioning and strategies to manage and prevent the increasing intensity and expansion of anthropogenic stressors in coastal areas.

Seasonal Prediction of Thermal Stress Accumulation for Coral Bleaching in the Tropical Oceans

Abstract Mass coral bleaching, associated with anomalously warm ocean temperatures over large regions, poses a serious threat to the future health of the world coral reef systems. Seasonal forecasts from coupled ocean–atmosphere models can be a valuable resource for reef management, providing early warning of potential bleaching conditions, allowing for a proactive management response. Here, the ability of a dynamical seasonal forecast model (Predictive Ocean Atmosphere Model for Australia, POAMA) to forecast degree heating months (DHMs) in the tropical oceans is assessed, with particular focus on the 1997/98 El Niño–Southern Oscillation (ENSO) and associated global bleaching events. The model exhibits useful skill in forecasting sea surface temperatures (SSTs) across the tropical oceans for 1982–2006 and reproduced both the magnitude and distribution of DHM values observed during the 1997/98 ENSO event. In general, observed teleconnections between ENSO indices and tropical SST at various lags are well captured by the model. In particular, strong observed correlations between peak ENSO indices and SST in the Caribbean in the following summer were reproduced. The model also shows skill in predicting ocean conditions conducive to bleaching in non-ENSO years, capturing the anomalously warm conditions in the Caribbean region in 2005. Probabilistic forecasts of DHM values above certain thresholds for the Caribbean show useful skill and could be valuable in the assessment of the likelihood of bleaching for the region.

Regulation of Apoptotic Mediators Reveals Dynamic Responses to Thermal Stress in the Reef Building Coral Acropora millepora

BackgroundMass 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.Methodology/Principal FindingsThe 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.Conclusions/SignificanceIn 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.

Caribbean Islands in a Changing Climate

The Caribbean Sea is the second largest sea in the world, covering an area of approximately 2,515,900 kilometers. The region has the largest number of small island developing states (SIDS) and the ...

The role of SCUBA diver user fees as a source of sustainable funding for coral reef marine Protected areas

Coral reefs are both highly diverse and economically important. Human activities, however, threaten the world's coral reefs, endangering their biological and economic value. No take Marine Protected Areas (MPA), which ban fishing within MPA boundaries, help conserve and restore reef health and provide ecological resilience to reefs in the face of global warming and ocean acidification. In many cases, cost-benefit analyses have provided strong support for the establishment of protected areas, but insufficient funding is often the largest obstacle to successful MPA implementation. SCUBA diving tourism is one method for financing coral reef conservation. Creating employment opportunities in the tourist industry provides an alternative to destructive fishing methods for the local community, and diver user fees can also be used to directly fund MPA management. While diver fees are a successful source of funding for some MPAs, more often than not, no fees are collected or the fees collected are inadequate to cover the costs of managing an MPA. This paper compares current user fees charged for diving in Caribbean MPAs and compares the fees to what tourists pay to reach their destination, for hotel rooms and other amenities. Fewer than one quarter of MPAs charged fees. Whhen charged, the fees were, on average, well below likely willingness-to-pay levels. Fees were more likely to be charged when NGOs were involved with MPA management.

Knowledge, Protection, Conservation and Management in the Marine Domain: The Example of the Mainland French Coast~!2009-08-19~!2010-01-18~!2010-04-06~!

France is geographically located in a central maritime position within the European Union (EU). Consequently, the experience gained and the solutions proposed in France may be of interest within a much wider geographical and institutional framework. The EU directives and regulations and the international treaties and conventions bind it. Among the 'tools' for environmental protection and management of the environment, we must point out: the Conservatory of Coastal Areas and Lakeshores, the 'Littoral' Law of 1 March 1986, the international conventions and European Directives (birds and habitats), the Inventory of the Flora and Fauna in Natural Marine Zones of Ecological Interest (ZNIEFF-Mer), the Mediterranean Blue Plan, the Barcelona Convention. More specially, we would enhance the practical interest, in the frame of the France's Strategic Action Plan for the marine environment, of the ZNIEFFs-Mer, the LITEAU (Littoral Eau) Program of the Ministry of the Environment, the French Marine Protected Areas Agency (MPAA). They are likely to lead to the protection of the littoral marine environment and beyond in the EEZ (Exclusive Economic Zone), along with a reasoned sustainable management of this environment. Integrated Coastal Zone Management (ICZM) is the method that has the best chance of success. In addition, the international scientific community has developed the concept of ecosystem-based management of marine resources, integrating a distinct human component into this 'eco-socio-system'. The role and the authority of the European Environment Agency must be increased in order to strengthen the cooperative links between the scientists in European countries. 2 of marine territory in EEZ (Exclusive Economic Zone), is present in all the oceans of the world, except the Arctic. The country's marine territories cover more than 10% of the world's coral reefs. It plays a very important role in accumulating knowledge about the world's natural heritage and marine resources, as well as knowledge about their exploitation, protection and conservation and thus the sustainable management of the sea. But, it is only recently, at the beginning of 1970s, that France, strongly rooted in the land, has begun reaching out decisively towards the sea. The successive administrations of not only the former French monarchies but also the country's first Republics, particularly after Napoleon's great sea defeats at the beginning of the 19th century, attempted to protect the country's terrestrial borders and develop the richness of its agriculture. The French Navy, maritime transport and fishing would develop over the course of time but without any true national environmental protection policy.

Making a Model Meaningful to Coral Reef Managers in a Developing Nation: a Case Study of Overfishing and Rock Anchoring in Indonesia

Most of the world's coral reefs line the coasts of developing nations, where impacts from intense and destructive fishing practices form critical conservation issues for managers. Overfishing of herbivorous fishes can cause phase shifts to macroalgal dominance, and fishers' use of rocks as anchors lowers coral cover, giving further competitive advantage to macroalgae. Overfishing and anchoring have been studied extensively, but the role of their interaction in lowering coral reef resilience has not been quantified formally. We analyzed the combined effects of overfishing and rock anchoring on a range of reef habitat types--varying from high coral and low macroalgae cover to low coral and high macroalgae cover--in a marine park in Indonesia. We parameterized a model of coral and algal dynamics with three intensities of anchoring and fishing pressure. Results of the model indicated that damage caused by rock anchoring was equal to or possibly more devastating to coral reefs in the area than the impact of overfishing. This is an important outcome for local managers, who usually have the funds to distribute less-damaging anchors, but normally are unable to patrol regularly and effectively enough to reduce the impact of overfishing. We translated model results into an interactive visual tool that allows managers to explore the benefits of reducing anchoring frequency and fishing pressure. The potential consequences of inaction were made clear: the likelihood that any of the reef habitats will be dominated in the future by macroalgae rather than corals depends on reducing anchoring frequency, fishing pressure, or both. The tool provides a platform for strengthened relationships between managers and conservationists and can facilitate the uptake of recommendations regarding resource allocation and management actions. Conservation efforts for coral reefs in developing nations are likely to benefit from transforming model projections of habitat condition into tools local managers can understand and interact with.

Coping with commitment: projected thermal stress on coral reefs under different future scenarios.

BackgroundPeriods of anomalously warm ocean temperatures can lead to mass coral bleaching. Past studies have concluded that anthropogenic climate change may rapidly increase the frequency of these thermal stress events, leading to declines in coral cover, shifts in the composition of corals and other reef-dwelling organisms, and stress on the human populations who depend on coral reef ecosystems for food, income and shoreline protection. The ability of greenhouse gas mitigation to alter the near-term forecast for coral reefs is limited by the time lag between greenhouse gas emissions and the physical climate response.Methodology/Principal FindingsThis study uses observed sea surface temperatures and the results of global climate model forced with five different future emissions scenarios to evaluate the “committed warming” for coral reefs worldwide. The results show that the physical warming commitment from current accumulation of greenhouse gases in the atmosphere could cause over half of the world's coral reefs to experience harmfully frequent (p≥0.2 year−1) thermal stress by 2080. An additional “societal” warming commitment, caused by the time required to shift from a business-as-usual emissions trajectory to a 550 ppm CO2 stabilization trajectory, may cause over 80% of the world's coral reefs to experience harmfully frequent events by 2030. Thermal adaptation of 1.5°C would delay the thermal stress forecast by 50–80 years.Conclusions/SignificanceThe results suggest that adaptation – via biological mechanisms, coral community shifts and/or management interventions – could provide time to change the trajectory of greenhouse gas emissions and possibly avoid the recurrence of harmfully frequent events at the majority (97%) of the world's coral reefs this century. Without any thermal adaptation, atmospheric CO2 concentrations may need to be stabilized below current levels to avoid the degradation of coral reef ecosystems from frequent thermal stress events.

Dynamical seasonal prediction of summer sea surface temperatures in the Great Barrier Reef

Coral bleaching is a serious problem threatening the world coral reef systems, triggered by high sea surface temperatures (SST) which are becoming more prevalent as a result of global warming. Seasonal forecasts from coupled ocean–atmosphere models can be used to predict anomalous SST months in advance. In this study, we assess the ability of the Australian Bureau of Meteorology seasonal forecast model (POAMA) to forecast SST anomalies in the Great Barrier Reef, Australia, with particular focus on the major 1998 and 2002 bleaching events. Advance warning of potential bleaching events allows for the implementation of management strategies to minimise reef damage. This study represents the first attempt to apply a dynamical seasonal model to the problem of coral bleaching and predict SST over a reef system for up to 6 months lead-time, a potentially invaluable tool for reef managers.

Colour vision in coral reef fish

Over many millions of years, sea creatures have developed a range of light reflectance properties. One example is the large variation in the patterns and colours of fish inhabiting the world's coral reefs. Attempts to understand the significance of the colouration have been made, but all too often from the perspective of a human observer. A more ecological approach requires us to consider the visual system of those for whom the colours were intended, namely other sea life. A first step is to understand the sensitivity of reef fish themselves to colour. Physiological data has revealed wavelength-tuned photoreceptors in reef fish, and this study provides behavioural evidence for their application in colour discrimination. Using classical conditioning, freshly caught damselfish were trained to discriminate coloured patterns for a food reward. Within 3-4 days of capture the fish selected a target colour on over 75% of trials. Brightness of the distracter and target were systematically varied to confirm that the fish could discriminate stimuli on the basis of chromaticity alone. The study demonstrates that reef fish can learn to perform two-alternative discrimination tasks, and provides the first behavioural evidence that reef fish have colour vision.

An ancient and variable mannose-binding lectin from the coral Acropora millepora binds both pathogens and symbionts

Corals form the framework of the world's coral reefs and are under threat from increases in disease and bleaching (symbiotic dysfunction), yet the mechanisms of pathogen and symbiont recognition remain largely unknown. Here we describe the isolation and characterisation of an ancient mannose-binding lectin in the coral Acropora millepora, which is likely to be involved in both processes. The lectin ('Millectin') was isolated by affinity chromatography and was shown to bind to bacterial pathogens as well as coral symbionts, dinoflagellates of the genus Symbiodinium. cDNA analysis of Millectin indicate extensive sequence variation in the binding region, reflecting its ability to recognise various mannose-like carbohydrate structures on non-self cells, including symbionts and pathogens. This is the first mannose-binding lectin to show extensive sequence variability as observed for pattern recognition proteins in other invertebrate immune systems and, given that invertebrates rely on non-adaptive immunity, is a potential keystone component of coral defence mechanisms.

Thresholds and the resilience of Caribbean coral reefs

The deteriorating health of the world's coral reefs threatens global biodiversity, ecosystem function, and the livelihoods of millions of people living in tropical coastal regions. Reefs in the Caribbean are among the most heavily affected, having experienced mass disease-induced mortality of the herbivorous urchin Diadema antillarum in 1983 and two framework-building species of coral. Declining reef health is characterized by increases in macroalgae. A critical question is whether the observed macroalgal bloom on Caribbean reefs is easily reversible. To answer this question, we must resolve whether algal-dominated reefs are an alternative stable state of the ecosystem or simply the readily reversible result of a phase change along a gradient of some environmental or ecological parameter. Here, using a fully parameterized simulation model in combination with a simple analytical model, we show that Caribbean reefs became susceptible to alternative stable states once the urchin mortality event of 1983 confined the majority of grazing to parrotfishes. We reveal dramatic hysteresis in a natural system and define critical thresholds of grazing and coral cover beyond which resilience is lost. Most grazing thresholds lie near the upper level observed for parrotfishes in nature, suggesting that reefs are highly sensitive to parrotfish exploitation. Ecosystem thresholds can be combined with stochastic models of disturbance to identify targets for the restoration of ecosystem processes. We illustrate this principle by estimating the relationship between current reef state (coral cover and grazing) and the probability that the reef will withstand moderate hurricane intensity for two decades without becoming entrained in a shift towards a stable macroalgal-dominated state. Such targets may help reef managers face the challenge of addressing global disturbance at local scales.

A World with Corals: What Will It Take?

If the article “A world without corals?” (News Focus, R. Stone, 4 May, p. 678) left you reaching for a stiff drink, you are not alone. The measures required to limit climate change can seem an eternity away to coastal communities left to deal with the consequences. Yet, since the 1997–98 mass bleaching—an unforgiving global event that destroyed 16% of the world's coral reefs—practitioners and scientists have worked to identify meaningful actions that can promote reef survival in the face of climate change. We believe it is more useful to ask, “What would it take to have a world with corals?” In this respect, the community responsible for the sustainable management of reefs has recently produced a series of consensus viewpoints ([1][1]–[3][2]). The emerging agenda stresses the need for a two-pronged approach: (i) global actions to reduce climate change and (ii) local actions to support ecosystem resilience. ![Figure][3] CREDIT: PHOTOS.COM The challenge of achieving international action on climate should not overshadow the significance of local interventions. Growing evidence suggests that local management will assist coral reefs through the period where we, as a global society, struggle to stabilize Earth's atmosphere. Strategies as broad as retaining herbivores ([4][4]), protecting naturally resilient areas (e.g., the sidebar “Palau combats coral bleaching,” C. Pala, 4 May, p. 680), and maintaining conditions for coral recruitment ([5][5]) appear to be effective for shoring up the resilience of reefs in preparation for the next 100 years of stress. Although the current greenhouse trajectory is disastrous for coral reefs and the millions of people who depend on them for survival, we should not be lulled into accepting a world without corals. Only by imagining a world with corals will we build the resolve to solve the challenges ahead. We must avoid the “game over” syndrome and marshall the financial, political, and technical resources to stabilize the climate and implement effective reef management with unprecedented urgency. 1. 1.[↵][6]“Coral Reefs and Climate Change, A Statement from the Third International Tropical Marine Ecosystem Management Symposium,” available at [www.itmems.org/Coral\_Reefs\_Climate_Change.pdf][7]. 2. 2.ICRI resolution on coral reefs and climate change, available at [www.icriforum.org/library/Reso\_CC\_Tokyo_0407.pdf][8]. 3. 3.[↵][9]1. H. Schuttenberg 2. et al. , “Building resilience into coral reef management: Key findings and recommendations,” summary prepared for the conference proceedings of the International Tropical Marine Ecosystem Management Symposium 2006, Cozumel, Mexico; see Supporting Online Material at [www.sciencemag.org/cgi/content/full/318/5847/42b/DC1][10]. 4. 4.[↵][11]1. T. P. Hughes 2. et al. , Curr. Biol. 17, 360 (2007). [OpenUrl][12][CrossRef][13][PubMed][14][Web of Science][15] 5. 5.[↵][16]1. T. McClanahan, 2. N. Polunin, 3. T. Done , Conserv. Ecol. 6, 18 (Dec. 2002)available at [www.consecol.org/vol6/iss2/art18][17]. [OpenUrl][18] [1]: #ref-1 [2]: #ref-3 [3]: pending:yes [4]: #ref-4 [5]: #ref-5 [6]: #xref-ref-1-1 View reference 1. in text [7]: http://www.itmems.org/Coral_Reefs_Climate_Change.pdf [8]: http://www.icriforum.org/library/Reso_CC_Tokyo_0407.pdf [9]: #xref-ref-3-1 View reference 3. in text [10]: http://www.sciencemag.org/cgi/content/full/318/5847/42b/DC1 [11]: #xref-ref-4-1 View reference 4. in text [12]: {openurl}?query=rft.jtitle%253DCurrent%2Bbiology%2B%253A%2B%2BCB%26rft.stitle%253DCurr%2BBiol%26rft.aulast%253DHughes%26rft.auinit1%253DT.%2BP.%26rft.volume%253D17%26rft.issue%253D4%26rft.spage%253D360%26rft.epage%253D365%26rft.atitle%253DPhase%2Bshifts%252C%2Bherbivory%252C%2Band%2Bthe%2Bresilience%2Bof%2Bcoral%2Breefs%2Bto%2Bclimate%2Bchange.%26rft_id%253Dinfo%253Adoi%252F10.1016%252Fj.cub.2006.12.049%26rft_id%253Dinfo%253Apmid%252F17291763%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [13]: /lookup/external-ref?access_num=10.1016/j.cub.2006.12.049&link_type=DOI [14]: /lookup/external-ref?access_num=17291763&link_type=MED&atom=%2Fsci%2F318%2F5847%2F42.2.atom [15]: /lookup/external-ref?access_num=000244463100028&link_type=ISI [16]: #xref-ref-5-1 View reference 5. in text [17]: http://www.consecol.org/vol6/iss2/art18 [18]: {openurl}?query=rft.jtitle%253DConserv.%2BEcol.%26rft.volume%253D6%26rft.spage%253D18%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx

A Diver's Perspective on Coral Damage

I must take exception to a comment and its implications in Richard Stone's otherwise excellent article “A world without corals?” (News Focus, 4 May, p. [678][1]). Stone introduces the human toll on reefs by citing damage inflicted by “divers clumsily breaking off chunks of coral.” It is undeniable that recreational divers will, on occasion, inadvertently injure corals. However, I have been a certified SCUBA diver since 1992 and have logged over 150 ocean dives all over the world, and in that time I have seen only sporadic instances of divers impacting corals. Formal dive training by all major certification agencies includes instruction on reef protection, and the vast majority of dive tour operators repeatedly lecture divers about avoiding contact with coral and other marine life. It is undeniable that our coral reefs are threatened by human activities, but it is unfair to imply that sport divers at all popular reefs contribute significantly to this plight. Rather than a threat, I would argue that the growth of recreational diving is a major benefit to the future of our reefs: Divers are among the most environmentally conscious individuals I have met (note the “army of snorkeling and diving volunteers” described in the article), and this pastime depends on having beautiful, healthy corals to explore. As proof of this view, one need only visit Bonaire, a popular dive destination and the site of some of the world's healthiest coral reefs. Bonaire instituted strong legislation, including laws enacted in 1975 that made it illegal to break or sell coral. Subsequent efforts in cooperation with the World Wildlife Fund established a vast marine park that completely encompasses the island. [1]: /lookup/doi/10.1126/science.316.5825.678

Sleeping Functional Group Drives Coral-Reef Recovery

The world's coral reefs are in decline, with many exhibiting a phase shift from coral to macroalgal dominance . This change is often associated with habitat loss and overharvesting of herbivorous fishes, particularly parrotfishes and surgeonfishes . The challenge is to reverse this decline and enhance the resilience of coral-reef ecosystems . We demonstrate, by using a large-scale experimentally induced phase shift, that the rapid reversal from a macroalgal-dominated to a coral- and epilithic algal-dominated state was not a result of herbivory by parrotfishes or surgeonfishes. Surprisingly, phase-shift reversal was primarily driven by a single batfish species (Platax pinnatus), a fish previously regarded as an invertebrate feeder. The 43 herbivorous fishes in the local fauna played only a minor role, suggesting that biodiversity may not offer the protection we hoped for in complex ecosystems. Our findings highlight the dangers faced by coral reefs and other threatened complex ecosystems: Species or functional groups that prevent phase shifts may not be able to reverse phase shifts once they occur. Nevertheless, reversal is possible. The critical issue is to identify and protect those groups that underpin the resilience and regeneration of complex ecosystems.

The Coral Probiotic Hypothesis

Emerging diseases have been responsible for the death of about 30% of corals worldwide during the last 30 years. Coral biologists have predicted that by 2050 most of the world's coral reefs will be destroyed. This prediction is based on the assumption that corals can not adapt rapidly enough to environmental stress-related conditions and emerging diseases. Our recent studies of the Vibrio shiloi/Oculina patagonica model system of the coral bleaching disease indicate that corals can indeed adapt rapidly to changing environmental conditions by altering their population of symbiotic bacteria. These studies have led us to propose the Coral Probiotic Hypothesis. This hypothesis posits that a dynamic relationship exists between symbiotic microorganisms and environmental conditions which brings about the selection of the most advantageous coral holobiont. Changing their microbial partners would allow the corals to adapt to changing environmental conditions more rapidly (days to weeks) than via mutation and selection (many years). An important outcome of the Probiotic Hypothesis would be development of resistance of the coral holobiont to diseases. The following evidence supports this hypothesis: (i) Corals contain a large and diverse bacterial population associated with their mucus and tissues; (ii) the coral-associated bacterial population undergoes a rapid change when environmental conditions are altered; and (iii) although lacking an adaptive immune system (no antibodies), corals can develop resistance to pathogens. The Coral Probiotic Hypothesis may help explain the evolutionary success of corals and moderate the predictions of their demise.

Heterogeneity of coral skeletons isotopic compositions during the 1998 bleaching event

The vulnerability of coral reefs to climate change, such as regional warming, became fully evident during the strong 1997-1998 El Nino event. This El Nino episode was associated with elevated sea-surface temperatures and caused mass mortality throughout many of the world's coral reefs. We analyzed the isotopic manifestation of this event in six Porites sp. coral skeletons from different localities in a small atoll (Alphonse) at the Seychelles Island. The aim was to validate the use of coral stable isotope compositions as recorders of such events in the past. The coupling between local-scale environment and global warming was weaker then expected, with regional warming being evident only when data from five colonies were averaged. Local conditions had a large effect on the isotopic compositions of coral skeletons. We conclude that future paleoclimate reconstructions, especially those attempts to identify past El Nino events, must be based on more than a single coral record. Moreover, the strong effect of local habitat on the isotopic composition of Porites sp. has to be considered when interpreting d 13 C and d

Report evaluates importance of coral reefs and mangroves

Thirty percent of the world's coral reefs are seriously damaged, and possibly no pristine reefs remain, according to a 24 January report by the World Conservation Monitoring Centre of the United Nations Environment Programme (UNEP) issued in the wake of the 26 December 2004 Indian Ocean tsunami.“The Indian Ocean tsunami brought a lot of attention to coral reefs and mangroves,” said Sue Wells, lead author of the report, In the Front Line: Shoreline Protection and other Ecosystem Services from Mangroves and Coral Reefs. “Were they badly damaged? Did they play a role in buffering damage on shore?”

Global assessment of coral bleaching and required rates of adaptation under climate change.

Elevated ocean temperatures can cause coral bleaching, the loss of colour from reef-building corals because of a breakdown of the symbiosis with the dinoflagellate Symbiodinium. Recent studies have warned that global climate change could increase the frequency of coral bleaching and threaten the long-term viability of coral reefs. These assertions are based on projecting the coarse output from atmosphere-ocean general circulation models (GCMs) to the local conditions around representative coral reefs. Here, we conduct the first comprehensive global assessment of coral bleaching under climate change by adapting the NOAA Coral Reef Watch bleaching prediction method to the output of a low- and high-climate sensitivity GCM. First, we develop and test algorithms for predicting mass coral bleaching with GCM-resolution sea surface temperatures for thousands of coral reefs, using a global coral reef map and 1985-2002 bleaching prediction data. We then use the algorithms to determine the frequency of coral bleaching and required thermal adaptation by corals and their endosymbionts under two different emissions scenarios. The results indicate that bleaching could become an annual or biannual event for the vast majority of the world's coral reefs in the next 30-50 years without an increase in thermal tolerance of 0.2-1.0°C per decade. The geographic variability in required thermal adaptation found in each model and emissions scenario suggests that coral reefs in some regions, like Micronesia and western Polynesia, may be particularly vulnerable to climate change. Advances in modelling and monitoring will refine the forecast for individual reefs, but this assessment concludes that the global prognosis is unlikely to change without an accelerated effort to stabilize atmospheric greenhouse gas concentrations.

Low coral cover in a high‐CO2 world

Coral reefs generally exist within a relatively narrow band of temperatures, light, and seawater aragonite saturation states. The growth of coral reefs is minimal or nonexistent outside this envelope. Climate change, through its effect on ocean temperature, has already had an impact on the world's coral reefs, with almost 30% of corals having disappeared since the beginning of the 1980s. Abnormally warm temperatures cause corals to bleach (lose their brown dinoflagellate symbionts) and, if elevated for long enough, to die. Increasing atmospheric CO2 is also potentially affecting coral reefs by lowering the aragonite saturation state of seawater, making carbonate ions less available for calcification. The synergistic interaction of elevated temperature and CO2 is likely to produce major changes to coral reefs over the next few decades and centuries. Known tolerances of corals to projected changes to sea temperatures indicate that corals are unlikely to remain abundant on reefs and could be rare by the middle of this century if the atmospheric CO2 concentration doubles or triples. The combination of changes to sea temperature and carbonate ion availability could trigger large‐scale changes in the biodiversity and function of coral reefs. The ramifications of these changes for the hundred of millions of coral reef–dependent people and industries living in a high‐CO2 world have yet to be properly defined. The weight of evidence suggests, however, that projected changes will cause major shifts in the prospects for industries and societies that depend on having healthy coral reefs along their coastlines.