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Marine heatwaves can cause coral bleaching and reduce coral cover on reefs, yet few studies have identified "bright spots," where corals have recently shown a capacity to survive such pressures. We analyzed 7714 worldwide surveys from 1997 to 2018 along with 14 environmental and temperature metrics in a hierarchical Bayesian model to identify conditions that contribute to present-day coral cover. We also identified locations with significantly higher (i.e., "bright spots") and lower coral cover (i.e., "dark spots") than regionally expected. In addition, using 4-km downscaled data of Representative Concentration Pathways (RCPs) 4.5 and 8.5, we projected coral cover on reefs for the years 2050 and 2100. Coral cover on modern reefs was positively associated with historically high maximum sea-surface temperatures (SSTs), and negatively associated with high contemporary SSTs, tropical-cyclone frequencies, and human-population densities. By 2100, under RCP8.5, we projected relative decreases in coral cover of40% on most reefs globally but projected less decline on reefs in Indonesia, Malaysia, the central Philippines, New Caledonia, Fiji, and French Polynesia, which should be focal localities for multinational networks of protected areas.

Ocean warming is increasing the incidence, scale, and severity of global-scale coral bleaching and mortality, culminating in the third global coral bleaching event that occurred during record marine heatwaves of 2014-2017. While local effects of these events have been widely reported, the global implications remain unknown. Analysis of 15,066 reef surveys during 2014-2017 revealed that 80% of surveyed reefs experienced significant coral bleaching and 35% experienced significant coral mortality. The global extent of significant coral bleaching and mortality was assessed by extrapolating results from reef surveys using comprehensive remote-sensing data of regional heat stress. This model predicted that 51% of the world’s coral reefs suffered significant bleaching and 15% significant mortality, surpassing damage from any prior global bleaching event. These observations demonstrate that global warming’s widespread damage to coral reefs is accelerating and underscores the threat anthropogenic climate change poses for the irreversible transformation of these essential ecosystems.

Coral reefs are exceptionally biodiverse and human dependence on their ecosystem services is high. Reefs experience significant direct and indirect anthropogenic pressures, and provide a sensitive indicator of coastal ocean health, climate change, and ocean acidification, with associated implications for society. Monitoring coral reef status and trends is essential to better inform science, management and policy, but the projected collapse of reef systems within a few decades makes the provision of accurate and actionable monitoring data urgent. The Global Coral Reef Monitoring Network has been the foundation for global reporting on coral reefs for two decades, and is entering into a new phase with improved operational and data standards incorporating the Essential Ocean Variables (EOVs) (www.goosocean.org/eov) and Framework for Ocean Observing developed by the Global Ocean Observing System. Three EOVs provide a robust description of reef health: hard coral cover and composition, macro-algal canopy cover, and fish diversity and abundance. A data quality model based on comprehensive metadata has been designed to facilitate maximum global coverage of coral reef data, and tangible steps to track capacity building. Improved monitoring of events such as mass bleaching and disease outbreaks, citizen science, and socio-economic monitoring have the potential to greatly improve the relevance of monitoring to managers and stakeholders, and to address the complex and multi-dimensional interactions between reefs and people. A new generation of autonomous vehicles (underwater, surface, and aerial) and satellites are set to revolutionize and vastly expand our understanding of coral reefs. Promising approaches include Structure from Motion image processing, and acoustic techniques. Across all systems, curation of data in linked and open online databases, with an open data culture to maximize benefits from data integration, and empowering users to take action, are priorities. Action in the next decade will be essential to mitigate the impacts on coral reefs from warming temperatures, through local management and informing national and international obligations, particularly in the context of the Sustainable Development Goals, climate action, and the role of coral reefs as a global indicator. Mobilizing data to help drive the needed behavior change is a top priority for coral reef observing systems. This paper benefited from the financial support to the authors provided by their institutions and the grants for research, monitoring and/or coordination they have secured. The development of this manuscript has been supported through ongoing work of the Global Coral Reef Monitoring Network and the Global Ocean Observing System�s Biology and Ecosystems Panel, supported by the International Coral Reef Initiative, United Nations Environment Programme, the United Nations Educational, Scientific and Cultural Organization�s Intergovernmental Oceanographic Commission, and Future Earth among others. Scopus

Thermal-stress events associated with climate change cause coral bleaching and mortality that threatens coral reefs globally. Yet coral bleaching patterns vary spatially and temporally. Here we synthesize field observations of coral bleaching at 3351 sites in 81 countries from 1998 to 2017 and use a suite of environmental covariates and temperature metrics to analyze bleaching patterns. Coral bleaching was most common in localities experiencing high intensity and high frequency thermal-stress anomalies. However, coral bleaching was significantly less common in localities with a high variance in sea-surface temperature (SST) anomalies. Geographically, the highest probability of coral bleaching occurred at tropical mid-latitude sites (15–20 degrees north and south of the Equator), despite similar thermal stress levels at equatorial sites. In the last decade, the onset of coral bleaching has occurred at significantly higher SSTs (∼0.5 °C) than in the previous decade, suggesting that thermally susceptible genotypes may have declined and/or adapted such that the remaining coral populations now have a higher thermal threshold for bleaching., Coral bleaching is generally linked to higher sea temperatures, but there may be geographic variation in this effect. Here, in a synthesis of global coral bleaching data, the authors show that bleaching probability is highest at mid-latitude sites despite equivalent thermal stress at equatorial sites.

The conservation status of 845 zooxanthellate reef-building coral species was assessed by using International Union for Conservation of Nature Red List Criteria. Of the 704 species that could be assigned conservation status, 32.8% are in categories with elevated risk of extinction. Declines in abundance are associated with bleaching and diseases driven by elevated sea surface temperatures, with extinction risk further exacerbated by local-scale anthropogenic disturbances. The proportion of corals threatened with extinction has increased dramatically in recent decades and exceeds that of most terrestrial groups. The Caribbean has the largest proportion of corals in high extinction risk categories, whereas the Coral Triangle (western Pacific) has the highest proportion of species in all categories of elevated extinction risk. Our results emphasize the widespread plight of coral reefs and the urgent need to enact conservation measures.

Because a sentence added in a revised version of the letter from Thomas J. Goreau et al . ([11 July, p. 165][1]) was not included in the printed letter, some readers may have formed the mistaken impression that the letter meant to criticize the purpose and value of the Reef Check 1997 project. That

I would like to elaborate on the article “Scientists launch survey of reef health” by Barbie Bischof (News & Comment, [6 June, p. 1494][1]) about the Reef Check survey. The first goal of the survey is to provide a scientific assessment of damage or degradation caused by human activity on coral reefs around the world, and the second is to raise public awareness of the socioeconomic and biodiversity value of coral reefs and of threats to reef “health.” This second goal is necessary if public and political support for solutions is to be gained. To achieve the first goal, the Reef Check scientific committee and advisers designed a simple protocol to assess the effects of human activity on the basis of a dozen easy-to-identify indicator species, such as long-spined black sea urchin (an overabundance of Diadema indicates overfishing) and butterflyfish (reduced populations indicate aquarium industry overharvesting). Two criteria were used to choose each indicator species: (i) Does it provide critical information about damage or degradation to reefs? and (ii) Can it be identified by a scuba-diving high-school student after about 1 day of training? Great care has been taken to design rigorous quality assurance and quality control procedures (per the International Standards Organization), including chain-of-custody documentation, trilayer error-checking, and use of automated data analysis spreadsheets. The draft Reef Check protocol was posted on the coral listserver of the U.S. National Oceanographic and Atmospheric Administration last year and was critiqued by many reef scientists. The protocol is now on the Reef Check web page at ˜webrc/reef.html. Over 100 experienced coral reef scientists from more than 30 countries have agreed to volunteer travel costs and time to train recreational divers, lead the field work, and sign a quality assurance pro forma. This commitment attests to their belief that Reef Check will produce valid and useful scientific data. The overwhelming support we have received from the scientific community indicates that reef scientists are no longer willing to settle for the same old “science as usual” attitude while their favorite reefs are systematically pillaged at an unprecedented rate. # Assessing Coral Reef Health {#article-title-2} We are part of a group of researchers, experienced in field recognition of Caribbean coral reef diseases, who are compiling data on emerging coral diseases around that region. The number of individuals currently able to correctly identify all forms of coral disease, bleaching, and other types of mortality in the field is limited, yet among them there still exists no firm consensus on the terminology or diagnostic features of many, perhaps most, diseases. This confusion is illustrated by the caption to the photograph accompanying Bischof's article ([p. 1494][1]), which identifies markings on coral as “white plague disease.” Two comprehensive (in preparation) compilations of coral diseases each describe “white plague disease” as completely different diseases, and neither of these diseases is the one called by that name in the photograph. The need for accurate assessment is urgent. Diagnostic criteria to identify different coral reef species and diseases are too subtle and require too high a proficiency in taxonomic identification to be adequately taught to sport divers during a single 1-hour training course in all of coral reef ecology. We therefore expect that the Reef Check survey could obscure or confuse the differences between diseases, bleaching, and other causes of mortality, and thus would not provide the kind of accurate data that researchers on coral diseases could use. Support is urgently needed for field monitoring efforts to document the spread of new and old diseases, and for laboratory work to identify them and their causes, before the significance of this rapidly intensifying threat to coral reefs can be understood. A workshop is scheduled to evaluate all current Caribbean coral reef diseases and produce a common classification scheme and nomenclature at the Association of Marine Laboratories of the Caribbean Annual Meeting, hosted by the University of Costa Rica in San Jose, Costa Rica, from 21 to 25 July 1997. # Assessing Coral Reef Health {#article-title-3} The photograph on page [1494][1] depicting a coral “beset by white plague disease” shows no evidence of white plague (or of any other known disease of scleractinian corals) on the Montastraea species, as shown. Numerous fish grazing scars, however, including some recovering lesions, appear to be present. It is also possible that these are bleached spots. White plague is characterized by the loss of tissue from the base of the colony progressing upward. While Montastraea is a known host, white plague is more common on other scleractinian species. [1]: /lookup/doi/10.1126/science.276.5318.1494

Hong Kong last month opened the Hong Kong Institute of Biotechnology (HKIB), a nonprofit R and D center. By combining Chinese expertise in medicinal compounds and cell culturing with Western technical and marketing skills, the institute hopes to develop products that could be licensed to Hong Kong or Western films. The institute is also developing experimental cell lines and making genetically engineered versions of promising compounds, taking advantage of the cell-culturing and cloning skills that are highly developed on the mainland. The Shanghai contingent is already involved in one of the institute's projects, an effort to transfer human genes into mouse fibroblasts to create cell lines for research on the molecular mechanisms of learning and memory. Other Chinese researchers are taking part in HKIB's joint venture with Syntex, which was signed last April. The mainland researchers extract candidate medicinal compounds from plants and microorganisms. In Hong Kong, the compounds are tested for their effects on neurotransmitter receptors, while Syntex scientists in Palo Alto study how the same compounds affect enzyme activity and whole cells.