Coral Bleaching

Dedication* " I"would"like"to"dedicate"this"paper"to"the"many"wonderful"people"that"have"helped" me:" " • To"my"wonderful"Mother"and"Father"for"allowing"me/"funding"me"to"have" this"amazing"experience"in"Madagascar" " • To"the"CNRO"and"staff"for"making"this"study"possible"and"enjoyable." " • To"all"of"the"SIT"Staff"for"the"amazing"experience"and"teaching." " • To"Gisele,"Thank"you"for"all"of"the"much"needed"help"and"expansive" knowledge" " • To"Bemoana"for"the"amazing"cooking"and"saving"us"from"the"pingys."We"love" you"more"than"you"will"ever"understand." " • To"Elena,"for"being"my"partner"in"crime/snorklebuddy."Lafo."Tsy"mila."Unreal." " • To"Casey,"for"feeding"me"Crocos,"being""that"vazaha""and"surviving"the"sauna" with"me."" " • To"Jack,"my"brother,"for"laughing"at"everything"with"me,"no"matter"how" strange."" " " " " " " " " " " " " " " " " " " " " 3"Acosta" " " " Coral"reefs"are"microcosms"of"biodiversity"and"life.""They"are"home"to"about"a" quarter"of"all"marine"life,"yet"amount"to"only"about"1%"of"the"world's"marine" environment."Coral"reefs"are"very"vulnerable"ecosystems;"there"are"numerous" threats"to"their"health,"such"as"damage"by"echinoderm"and"fish"feeding,"natural" disasters,"coral"illness"and"bleaching"events.""Coral"health"fluctuates"according"to" many"of"these"factors"and"as"a"result"of"the"fragile"symbiotic"balance"between" zooxanthellae"algae"and"corals.""Subsequently,"coral"health"is"an"essential"topic"for" analysis"and"assessment.

Many cnidarians, including the reef-building corals, undergo symbiotic mutualisms with photosynthetic dinoflagellate algae of the family Symbiodiniaceae. These partnerships are sensitive to temperature extremes, which cause symbiont loss and increased coral mortality. Previous studies have implicated host immunity and specifically immunity transcription factor NF-κB as having a role in the maintenance of the cnidarian-algal symbiosis. Here we have further investigated a possible role for NF-κB in establishment and loss of symbiosis in various strains of the anemone Exaiptasia (Aiptasia) and in the coral Pocillopora damicornis. Our results show that NF-κB expression is reduced in Aiptasia larvae and adults that host certain algae strains. Treatment of Aiptasia larvae with a known symbiosis-promoting cytokine, transforming growth factor β, also led to decreased NF-κB expression. We also show that aposymbiotic Aiptasia (with high NF-κB expression) have increased survival following infe...

Coastal ecosystems are disproportionally inhabited by global human population. Consequently, human impacts originating from land and sea combine with climate-driven disturbances to fundamentally restructure nearshore marine ecosystems. These coincident human stressors are especially acute in the tropics where population centres concentrate along shorelines and marine heatwaves increasingly trigger mass coral bleaching and mortality. However, despite decades of research, we lack consensus as to whether local management supports coral reef resilience under climate change. Here we combined recurring reef surveys with a unique time series of land-sea human impacts over a 20-year period that encompassed an unprecedented marine heatwave in Hawaiʻi. Reefs with high fish biomass and reduced land-based impacts such as wastewater pollution had positive coral trajectories pre-disturbance and experienced minimal coral loss following severe heat stress. Concurrent land-sea management resulted in...

Disturbances that result in the mass mortality of reef-building corals are changing the appearance of reefs worldwide. Many reefs are transitioning away from scleractinian-coraldominated assemblages to benthic communities composed primarily of non-scleractinian taxa. This study evaluated recovery patterns of reef communities in the Florida Keys following the mortality associated with the 1997/1998 El Niño. We examined temporal trends among the 5 most spatially abundant reef taxa and stony coral species from 1999 to 2009 at 3 spatial scales, and applied a Principal Coordinate Analysis (PCoA) to determine whether changes in their cover resulted in a shift in community structure. Trends of decreasing stony coral cover were not identified Keys-wide between 1999 and 2009, but 2 of the 3 habitats examined -shallow and deep forereefs -did show a significant decline in cover. Concomitantly, octocoral cover significantly increased Keys-wide and in all 3 habitats. The transition to octocorals was most evident on shallow forereefs, where octocoral cover significantly increased at 9 of 12 reefs and overwhelmingly influenced the PCoA. On deep forereefs, octocoral and sponge cover did significantly increase, but did not impart a clearly defined shift in community structure like that observed on shallow forereefs. Community composition at patch reefs was relatively consistent during the study, but the increase in octocoral cover may accelerate further following a cold-water mortality event in 2010. These results demonstrate that octocorals are emerging as the predominant benthic taxa in the Florida Keys. Although the transition to octocorals may have started long ago, their apparent resilience to present-day stressors will likely allow this shift to continue into the foreseeable future.

Kabung Island is located in Bengkayang Regency, West Kalimantan. Kabung Island has a small area but has wealth and beauty that can attract tourists to come for a tour, one of which is the beauty of coral reefs. Monitoring the condition of coral reefs can be done in various ways. The utilization of remote sensing with different satellite images can monitor coral reefs in a wide area. This study aimed to create a map of the location of coral reefs on Kabung Island using medium resolution and high-resolution images. This study uses primary data, which specific methods will then process. The data are Sentinel-2 MSI Level 2A Satellite Imagery for mediumresolution image data and Birds Eye Satellite Imagery for high resolution imagery. The results of the classification of Bird Eye images obtained that the area of each class is the area of live coral on Kabung Island of 1.969 ha, dead coral of 1.1521 ha and sand or substrate of 1.7451 ha. It can be seen that the live coral class dominates i...

We studied the effect of chronic oxybenzone exposure and elevated temperature on coral health. Microcolonies of Stylophora pistillata and Acropora tenuis were cultured in 20 flow-through aquaria, of which 10 were exposed to oxybenzone at a field-relevant concentration of ~0.06 μg L−1 at 26 °C. After two weeks, half of the corals experienced a heat wave culminating at 33 °C. All S. pistillata colonies survived the heat wave, although heat reduced growth and zooxanthellae density, irrespective of oxybenzone. A. tenuis survival was reduced to 0% at 32 °C, and oxybenzone accelerated mortality. Oxybenzone and heat significantly reduced photosynthetic yield in both species, causing a 5% and 22−33% decrease, respectively. In addition, combined oxybenzone and temperature stress altered the abundance of five bacterial families in the microbiome of S. pistillata. Our results suggest that oxybenzone adds insult to injury by further weakening corals in the face of global warming.Highlights➢Chro...

This paper discusses land-sourced pollution with an emphasis on domestic sewage in the Caribbean in relation to similar issues in the Indian Ocean and Pacific. Starting on a large-scale in the 1980s, tropical Atlantic coastlines of Florida and Caribbean islands were over-developed to the point that traditional sewage treatment and disposal were inadequate to protect fragile coral reefs from eutrophication by land-sourced nutrient pollution. This pollution caused both ecological and public health problems. Coral reefs were smothered by macro-algae and died, becoming rapidly transformed into weedy algal lawns, which resulted in beach erosion, and loss of habitat that added to fisheries collapse previously caused by over-fishing. Barbados was one of the first countries to recognize this problem and to begin implementation of effective solutions. Eastern Africa, the Indian Ocean Islands, Pacific Islands, and South East Asia, are now starting to develop their coastlines for ecotourism, like the Caribbean was in the 1970s. Tourism is an important and increasing component of the economies of most tropical coastal areas. There are important lessons to be learned from this Caribbean experience for coastal zone planners, developers, engineers, coastal communities and decision makers in other parts of the world to assure that history does not repeat itself. Coral reef die-off from land-sourced pollution has been eclipsed as an issue since the ocean warming events of 1998, linked to global warming. Addressing ocean warming will take considerable international cooperation, but much of OPEN ACCESS the land-sourced pollution issue, especially sewage, can be dealt with on a watershed by watershed basis by Indian Ocean and Pacific countries. Failure to solve this critical issue can adversely impact both coral reef and public health with dire economic consequences, and will prevent coral reef recovery from extreme high temperature events. Sewage treatment, disposal options, and nutrient standards are recommended that can serve as a reference point but must be fine-tuned to local ecology.

Ocean warming is one of the greatest global threats to coral reef ecosystems; it leads to the disruption of the coral–dinoflagellate symbiosis (bleaching) and to nutrient starvation, because corals mostly rely on autotrophy (i.e., the supply of photosynthates from the dinoflagellate symbionts) for their energy requirements. Although coral bleaching has been well studied, the early warning signs of bleaching, as well as the capacity of corals to shift from autotrophy to heterotrophy, are still under investigation. In this study, we evaluated the bleaching occurrence of the scleractinian coral Mussismillia harttii and the hydrocoral Millepora alcicornis during a natural thermal stress event, under the 2015–2016 El Niño influence in three reef sites of the South Atlantic. We focused on the link between peroxynitrite (ONOO−) generation and coral bleaching, as ONOO− has been very poorly investigated in corals and never during a natural bleaching event. We also investigated the natural tr...

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.

Predicting the bleaching responses of corals is crucial in light of frequent heat stress events to manage further losses of biodiversity and ecosystem functioning, especially for reefs impacted by urbanisation. We examined if the coral cover and community at various Singapore sites changed during the 2016 global coral bleaching event. Bleaching prevalence varied widely among sites in June 2016, and was best explained by site and coral species. While some sites were minimally impacted, others registered significant decreases in coral cover and community changes persisting till March 2017, when normal colouration was mostly regained by corals. Bleaching susceptibility was associated with larger corallites in hermaphrodites and smaller corallites in gonochores (probably due to the cost of maintaining dual sexual functions in hermaphrodites), and with increasing proximity between polyps (likely because thermal damage would be less contained among polyps with greater physiological integration). However, bleaching resilience-the capacity to regain baseline pigmentation-was poorly explained by the traits studied. Our findings suggest that the interplay between local conditions and species composition strongly affects bleaching outcomes on urbanised reefs, and underscore the utility of coral traits for predicting bleaching responses to help in formulating appropriate management strategies.

A total of 234 species of fish have been recorded from the St Martin Island. Of which, 98 species are coral associated. The total number of recorded mollusc and crab species stands at 187 and 7 species respectively. A total of 66 coral species were recorded, of which 19 are fossil corals, 36 living corals and the rest are under 6 families of subclass Octocorallia (soft corals). A total of 14 species of algae have been recorded from the St. Martin's Island. There is an estimated amount of 1500 MT red sea weed biomass available around the St. Martin's Island. The island contains some of the most unique, benthic community associations in Bangladesh, not found anywhere else in the South Asian region. The unique marine communities have very high scientific value for research and monitoring and there are only a few examples worldwide, where coral-algal communities dominate rocky reefs. The economy of the island is based on fishing. It is estimated that, about 1650 MT of fish are caught annually. Over-exploitation of renewable marine and coastal resources (e.g., rocky reef fisheJies, coral and shell extraction; removal of coastal vegetation from inter-tidal and sub-tidal habitats) is a major threat to this ecosystem. Destructive fishing practices, mainly the use of rock-weighted gill nets over the inshore boulder reefs is of prime aggravates. Proper implementation of the rules and regulation for 'Ecologically Critical Areas' ('ECA 's), alternative livelihood for the local people and further research should be immediately taken for sustainable utilization and to save the rich biodiversity of the only coral island in Bangladesh.

In the last decade, corals from northeastern Brazil have experienced bleaching events linked to thermal anomalies, the consequences of which have been the appearance of disease outbreaks affecting different species. As a way to explain and monitoring diseases progression and other characteristics regarding the identification in the field for coral diseases, this article aimed to demonstrate the particularities that follows each diseases symptom. This study presents the results of an assessment of the presence of coral diseases on six coastal reefs in northeastern Brazil, including marine protected areas. After 300 hours of visual censuses, a total of 875 colonies were observed; of these, 114 colonies had some disease, representing 13.02% of the colonies analyzed. Five diseases/syndromes were recorded in four host coral species: white syndrome, white plague, red band, dark spots, and white band. This is the first record of white band on the Brazilian coast. The massive coral Siderast...

Anomalous heat waves are causing a major decline of hard corals around the world and threatening the persistence of coral reefs. There are, however, reefs that have been exposed to recurrent thermal stress over the years and whose corals appear to have been tolerant against heat. One of the mechanisms that could explain this phenomenon is local adaptation, but the underlying molecular mechanisms are poorly known. In this work, we applied a seascape genomics approach to study heat stress adaptation in three coral species of New Caledonia (southwestern Pacific) and to uncover the molecular actors potentially involved. We used remote sensing data to characterize the environmental trends across the reef system, and sampled corals living at the most contrasted sites. These samples underwent next generation sequencing to reveal single nucleotide polymorphisms (SNPs), frequencies of which were associated with heat stress gradients. As these SNPs might underpin an adaptive role, we characterized the functional roles of the genes located in their genomic region. In each of the studied species, we found heat stress-associated SNPs located in proximity of genes involved in pathways well known to contribute to the cellular responses against heat, such as protein folding, oxidative stress homeostasis, inflammatory and apoptotic pathways, and DNA damage-repair. In some cases, the same candidate molecular targets of heat stress adaptation recurred among species. Together, these results underline the relevance and the power of the seascape genomics approach for the discovery of adaptive traits that could allow corals to persist across wider thermal ranges.

Coral reefs are suffering a major decline due to the environmental constraints imposed by climate change. Over the last 20 years, three major coral bleaching events occurred in concomitance with anomalous heatwaves, provoking a severe loss of coral cover worldwide. The conservation strategies for preserving reefs, as they are implemented now, cannot cope with global climatic shifts. Consequently, researchers are advocating for preservation networks to be set-up to reinforce coral adaptive potential. However, the main obstacle to this implementation is that studies on coral adaption are usually hard to generalize at the scale of a reef system. Here, we study the relationships between genotype frequencies and environmental characteristics of the sea (seascape genomics), in combination with connectivity analysis, to investigate the adaptive potential of a flagship coral species of the Ryukyu Archipelago (Japan). By associating genotype frequencies with descriptors of historical environmental conditions, we discovered six genomic regions hosting polymorphisms that might promote resistance against heat stress. Remarkably, annotations of genes in these regions were consistent with molecular roles associated with heat responses. Furthermore, we combined information on genetic and spatial distances between reefs to predict connectivity at a regional scale. The combination of these results portrayed the adaptive potential of this population: we were able to identify reefs carrying potential heat stress adapted genotypes and to understand how they disperse to neighbouring reefs. This information was summarized by objective, quantifiable and mappable indices covering the whole region, which can be extremely useful for future prioritization of reefs in conservation planning. This framework is transferable to any coral species on any reef system and therefore represents a valuable tool for empowering preservation efforts dedicated to the protection of coral reefs in warming oceans.

Coral reefs are suffering a major decline due to the environmental constraints imposed by climate change. Over the last 20 years, three major coral bleaching events occurred in concomitance with anomalous heatwaves, provoking a severe loss of coral cover worldwide. The conservation strategies for preserving reefs, as they are implemented now, cannot cope with global climatic shifts. Consequently, researchers are advocating for preservation networks to be set-up to reinforce coral adaptive potential. However, the main obstacle to this implementation is that studies on coral adaption are usually hard to generalize at the scale of a reef system. Here, we study the relationships between genotype frequencies and environmental characteristics of the sea (seascape genomics), in combination with connectivity analysis, to investigate the adaptive potential of a flagship coral species of the Ryukyu Archipelago (Japan). By associating genotype frequencies with descriptors of historical environmental conditions, we discovered six genomic regions hosting polymorphisms that might promote resistance against heat stress. Remarkably, annotations of genes in these regions were consistent with molecular roles associated with heat responses. Furthermore, we combined information on genetic and spatial distances between reefs to predict connectivity at a regional scale. The combination of these results portrayed the adaptive potential of this population: we were able to identify reefs carrying potential heat stress adapted genotypes and to understand how they disperse to neighbouring reefs. This information was summarized by objective, quantifiable and mappable indices covering the whole region, which can be extremely useful for future prioritization of reefs in conservation planning. This framework is transferable to any coral species on any reef system and therefore represents a valuable tool for empowering preservation efforts dedicated to the protection of coral reefs in warming oceans.

In response to the global decline in coral reefs, the U.S. Coral Reef Task Force's National Action Plan to Conserve Coral Reefs called for the creation of a Coral Disease and Health Consortium (CDHC) to organize and coordinate the scientific resources of the U.S. and its territories to meet the challenge of globally declining coral reefs. Its mission is to preserve and protect the health of coral reef ecosystems through an understanding of the effects of natural and anthropogenic stressors on reef-building communities. The CDHC serves to unify the coral health and disease research community, identify research priorities, and encourage a new generation of coral researchers through education and outreach. The biomedical perspective and innovative technologies developed from Consortium efforts is envisioned to give scientists, resource managers, and industry new tools to identify and alleviate hidden stresses before they become environmental health crises. Currently over 125 partners, including federal agencies, NOAA, DOI, EPA, along with academia, non-profit and industry, contribute their time and expertise to the CDHC, while organizational infrastructure is supported by the congressionally funded NOAA Coral Reef Conservation Program.

The most extensive and severe bleaching of coral ever recorded occurred in 1997 and 1998 as a result of anomalously high sea-surface temperatures. In the Ryukyu Islands, extensive bleaching occurred from late July to early October in 1998. A time-series transect study on a reef flat revealed the different responses of coral populations among species to this event. Coral cover was monitored just before, during, and 6 times after the bleaching occurred, along 5 fixed transects, 710 to 800 m long, across the reef flat of Shiraho Reef, Ishigaki Island, in the Ryukyu Islands of Japan. The dominant corals were Heliopora coerulea, massive Porites, and branching Porites, Montipora, Acropora, and Pavona (these latter 4 genera could not always be distinguished to species level, and are thus grouped by genus and ecoform). H. coerulea was the least susceptible to bleaching and maintained almost constant coverage before and after the bleaching. Massive Porites were susceptible to bleaching, but regained their algae after the bleaching and sustained their coverage. On the other hand, the branching Porites, Montipora, and Acropora were susceptible to bleaching and mortality was high. Coverage by branching Montipora was initially reduced by 66%, but by 2 yr after the bleaching it had recovered to pre-bleaching coverage. However, only large patches of more than 70 m along a transect, with coverage of 10 to 40%, recovered. Small patches of less than 30 m along a transect, with coverage of less than 10%, died and did not recover. The response of corals to bleaching differs according to the strategy the coral uses against bleaching; moderately frequent and severe bleaching might permit the coexistence of both types of corals on the same reef flat, as in the case of Shiraho Reef.

HF radars have been installed in many coastal sites around the world to monitor ocean parameters between the coast and maximum of about 250 km offshore. The main product of phased array radars is gridded maps of surface currents, wave heights and wind directions. Maps of surface currents (see Figure 1) can be produced every 10 – 20 minutes which, in real-time, improve navigation safety in restricted areas commonly found near ports and harbours. The time-sequence of surface current maps enables Langrangian tracking of small parcels of surface water. This analysis of the data is being used for hazard mitigation in managing suspended sediments in dredging, in emergency situations where flotsam and other drifting items need to be found, and in pollution control. Additionally the surface current measurement capability is used to assist tsunami warnings. The newly launched Tsunami Warning Center in Oman includes a network of phased-array HF radars to provide real-time tsunami monitoring. ...

Coral bleaching is an ecological response to stressful physical conditions observed to occur when strong insolation coupled with stratification of the water column leads to anomalous warming of the surface water. Stratfication requires calm winds, the absence of waves, and an absence of currents: conditions which result in limited mixing of the water column and thus confine heat due to insolation at the ocean surface. There is a strong need to identify which of the physical parameters are more significant at any given time and, more importantly, to monitor the physical parameters in near realtime to serve as a tool for long-term planning and management for marine parks and coastal waters. This paper reviews the contribution that currents make to mixing in the water column through the dissipation of turbulent kinetic energy and takes a further step to evaluate the use of surface current data to provide an index of vertical mixing. In this work, when the surface current speed is greater than a critical value, the water column is found to be vertically mixed even in the absence of wind or waves. A phased array HF Ocean Radar deployed in the southern part of the Great Barrier Reef provides a map of surface currents with high spatial resolution (4km) every 10 minutes over the grid. These surface currents are used to predict vertical stratification and mixing which can then be used as an indication for conditions under which bleaching might occur.

Climate change is perhaps the greatest threat to coral reefs worldwide. However, there is spatial variation in the extent and severity of this disturbance, with offshore and well-managed reefs presumed to minimize the consequences. In this study, sh and benthic communities at the offshore and wellmanaged reefs of Apo Reef Natural Park, Philippines was examined during (2016), 2 years (2018) and 3 years (2019) after bleaching disturbance. Fish and benthic surveys were conducted on scuba at 5 sites at depths of 8-10m. Results showed that benthic communities varied more strongly with year attributed to changes in the benthic cover of coral. These changes were also in uenced by site, with some sites experiencing coral loss of 41-48%, while at other sites there were minimal changes. These site differences were associated with the cover of coral pre-bleaching, with higher cover prior to the disturbance contributing to larger losses. Fish communities varied more with sites associated with differences in the predominant benthos among sites. The stability of sh communities with year despite coral loss may be attributed to the variable loss of coral cover among sites. For sites that experienced high losses of coral cover, the presence of alternative and/or deeper habitats may have provided shelter and food for shes maintaining taxonomic composition within sites. This study shows that bleaching disturbance circumvents localized protection, but impacts are variable even at small (≤ 3km) spatial scales. Community composition pre-bleaching and alternative habitats seem to buffer against the consequences of bleaching disturbance.

Here, we examined the coral bleaching responses during the 2016 thermal stress event and post-bleaching changes in coral communities in the heavily disturbed reefs of the Bolinao-Anda Reef Complex (BARC), northwestern Philippines. Less than 25% of colonies bleached, with 77% attributed to five genera (Dipsastrea, Porites, Fungia, Seriatopora, and Montipora). Coral bleaching prevalence was associated with site location, coral composition, and coral abundance, suggesting that small-scale variation (< 20 km) in coral communities (taxa and density) influences spatial variation in coral bleaching prevalence. There was no noticeable change in coral composition and cover two years after the bleaching event as exposure to chronic disturbance likely selected for the dominance of stress tolerant coral taxa and communities. Results show that the 2016 thermal stress event caused coral bleaching but with low prevalence at the BARC, which suggests that disturbed reefs may provide spatial refuge to coral communities from thermal stress.

Karimunjawa is one of the archipelago in the north of Java island. It has uniqueness of nature. In these archipelago, five forms of ecosystems can be found. One of the exciting ecosystems and the main attraction of tourists who come to Karimunjawa is Coral Reef. The number of tourists who visit to Karimunjawa is increase along with the ease of transportation and the many choices of modes to Karimun although in the west monson This condition would bring both positive and negative impacts. The increase number of tourists who visit to Karimunjawa has not been followed by the readiness to provide adequate infrastructure.It is causing the emergence of various problems in Karimunjawa. The aims of this study is to reveal the problems of public infrastructure in developing tourist destinations in coastal areas and small islands. This research uses rationalistic deductive method, with empirical description analysis technique. The findings obtained from this research are the emergence of envi...

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.

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 six years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Niña conditions than they were in 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 coming decades. The average surface temperature of our planet has risen by close to 1 o C since the 1880s (1), and global temperatures in 2015 and 2016 were the warmest since instrumental records began in the 19 th century (2). Recurrent regional-scale (>1000 km) bleaching and mortality of corals is a

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 anthropo...

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 . Here we show that in the aftermath of the record-breaking marine heatwave on the Great Barrier Reef in 2016 , 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&#39;s largest coral reef system. Our study bridges the gap between the theory and...

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&#39;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 ...

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.

Coral reefs within the Florida Keys are disappearing at an alarming rate. Coral cover in the Florida Keys National Marine Sanctuary declined by 38% from 1996 to 2000. In 2000, populations of Montastraea annularis at four sites near Molasses Reef within the Florida Keys National Marine Sanctuary and one reef within Biscayne National Park were sampled on a quarterly basis. Anecdotal observations showed corals at AlinaÕs Reef in Biscayne National Park appeared healthy in March, but experienced an acute loss of coral cover by August. Cellular Diagnostic analysis indicated that AlinaÕs Reef corals were in distress: they had been afflicted with a severe oxidative damaging and protein-denaturing stress that affected both the corals and their symbiotic zooxanthellae. This condition was associated with a significant xenobiotic detoxification response in both species, reflecting probable chemical contaminant exposure. These results demonstrate that applying a Cellular Diagnostic approach can be effective in helping to identify stress and its underlying causes, providing diagnostic and prognostic biomarkers of coral health.

Handline is the most popular fishing gear used by fishers inhabits coastal area in Ambon Island, Maluku, Indonesia. In the recent years, catches by handline fishers tend to decrease, therefore they try to modify the gear through mechanization to improve their catches. This research was conducted in the waters of Ambon Island to compare catches between traditional and mechanized hand liner. Totally, there were 18 species consist of 88 individuals with 98.61 kg in weight caught during the research. Mechanized handline caught more species and more weight but less in duration of hauling compare to traditional one. Mean weight and mean length of the fishes caught were significantly different in relation to duration of hauling for both types of handlines.

Calcium carbonate (CaCO 3 ) is the main component of the skeleton of scleractinian corals and is a preferable substrate for attachment and growth. An electro-stimulation method based on the electrolysis of seawater, which generates calcium and magnesium minerals as a crystalline coating over artificial metal structures, was used to boost coral growth during the 1970s. Few studies have attempted to compare survival and growth between electro-stimulated corals and non-electro-stimulated corals in situ. In this study, we used 2D image analysis to quantify the growth of branching and massive corals on electrostimulated structures. Among four metallic structures that were deployed in Sabang, Aceh, Indonesia, three were electro-stimulated (12 V) and one was used as a control. Two branching corals (Acropora gemmifera and Pocillopora verrucosa) and two massive coral species (Porites murrayensis and Porites lobata) were selected. A total of 256 fragments, comprising 128 fragments derived from two branching species and 128 fragments derived from two massive species, were randomly dispatched to each structure. Underwater photographs were taken at three intervals from August 2019 to December 2020. The results showed that the survival rates (excluding lost fragments) of branching corals under electro-stimulation were approximately 19% higher than massive. However, no significant difference was found between the survival rates of the treatment and control groups for both branching and massive corals. Furthermore, we found that under electro-stimulation, branching corals grew faster than controls but not massive. Our study provides pieces of evidence for the potential use of electrochemical processes in stimulating the growth of branching corals.

The loss of zooxanthellae during a short-term, experimentally simulated bleaching event resulted in significant changes to the secondary metabolite chemistry of the alcyonacean soft corals Sinularia flexibilis and Lobophytum compactum. The concentration of flexibilide, the most active cytotoxic secondary metabolite (with antimicrobial properties) in the tissues of Sinularia flexibilis increased by 126%, while that of its principal terpenoid algaecide, sinulariolide,

. Impacts of bleaching on the soft coral Lobophytum compactum. I. Fecundity, fertilisation and offspring viability. Coral Reefs, in press (Chapter 6). Michalek-Wagner, K. and B.L. Willis (2000). Impacts of bleaching on the soft coral Lobophytum compactum. II. Biochemical changes in adults and their gametes. Coral Reefs, in press (Chapter 7). Michalek-Wagner, K. and B. F. Bowden (1999). The effects of bleaching on the secondary metabolite chemistry of alcyonacean soft corals. Submitted to Journal of Chemical Ecology, in press (Chapter 4). Michalek-Wagner, K., Bourne, D.J. and B. F. Bowden (1999). The impact of zooxanthellae on secondary metabolite chemistry and development of the soft coral Lobophytum compactum. To be submitted to Limnology and Oceanography (Chapter 5). Michalek-Wagner, K. (1999). Seasonal variation in UV-protecting mycosporine-like amino acids of soft corals. To be submitted to Marine Biology (Chapter 2). Michalek-Wagner, K. (1999). The role of UV-absorbing mycosporine-like amino acids in the coral bleaching process. To be submitted to Marine Ecology Progress Series (Chapter 3).

Extreme warming events that contribute to mass coral bleaching are occurring with increasing regularity, raising questions about their effect on coral reef ecological interactions. However, the effects of such events on parasite-host interactions are largely ignored. Gnathiid isopods are common, highly mobile, external parasites of coral reef fishes, that feed on blood during the juvenile stage. They have direct and indirect impacts on their fish hosts, and are the major food source for cleaner fishes. However, how these interactions might be impacted by increased temperatures is unknown. We examined the effects of acute temperature increases, similar to those observed during mass bleaching events, on survivorship of gnathiid isopod juveniles. Laboratory experiments were conducted using individuals from one species (Gnathia aureamaculosa) from the Great Barrier Reef (GBR), and multiple unknown species from the central Philippines. Fed and unfed GBR gnathiids were held in temperature...

The increasing frequency of coral bleaching events is beginning to greatly impact dive tourism destinations, and the Caribbean region is no exception. With this region being highly dependent on tourism, of which dive tourism is a valued part, the Caribbean and its tourism industry have much to lose. This paper examines the impacts of coral bleaching on dive tourism operators across the Caribbean region. This multi-phase study consists of interviews with Tobago dive operators, which took place in January 2011, and a web-based survey, which will be emailed to dive operators Caribbean wide April 2011.

Funding was provided by the European Union through the Indian Ocean Commission's Biodiversity Project Maps were produced from open source country and coral reef layers by James Mbugua, CORDIO East Africa. The designation of geographical entities in this report, and the presentation of the material, do not imply the expression of any opinion whatsoever concerning the legal status of any country, territory, or area, or of its authorities, or concerning the delimitation of frontiers or boundaries.

The Ocean Biogeographic Information System (OBIS) began in 2000 as the repository for data from the Census of Marine Life. Since that time, OBIS has expanded its goals beyond simply hosting data to supporting more aspects of marine conservation (Pooter et al. 2017). In order to accomplish those goals, the OBIS secretariat in partnership with its European node (EurOBIS) hosted at the Flanders Marine Institute (VLIZ, Belgium), and the Intergovernmental Oceanographic Commission (IOC) Committee on International Oceanographic Data and Information Exchange (IODE, 23rd session, March 2015, Brugge) established a 2-year pilot project to address a particularly problematic issue that environmental data collected as part of marine biological research were being disassociated from the biological data.  OBIS-Event-Data is the solution that was developed from that pilot project, which devised a method for keeping environmental data together with the biological data (Pooter et al. 2017). OBIS is se...

Coral bleaching is well documented on shallow, tropical reefs; however, there are few published records of coral bleaching on high latitude (>26°), deeper (>20 m) reefs (see for a recent example of bleaching on a high latitude, shallow reef). High latitude, deeper reefs are thought to be less affected by thermal stress and therefore may act as potential refuge sites from the adverse impacts of global warming ). Here, we observed extensive species-specific coral bleaching in May 2011 at two high latitude, deeper (24-28 m) reefs located on the western side of Rottnest Island, Western Australia (32°00¢S, 115°31¢E). Rottnest Island has well-developed coral assemblages that include 25 species in 16 genera . Most colonies of Coscinaraea marshae (n % 100), a species endemic to southern Australia, were completely bleached and colonized by flatworms, while all other coral genera were unbleached (Fig. ). Ninety-five percent of bleached colonies of C. marshae remained alive after 4 weeks, although partial mortality was evident in approximately 20% of colonies. Water temperatures between December 2010 and May 2011 at these sites were higher than average and NOAA SST records reveal 16-degree heating weeks (DHW) for the region (). In situ measurements recorded hourly by Hobo TM loggers confirmed temperatures were up to 4°C higher (maximum = 26.4°C) than the long-term monthly average (21.5-21.9°C) for the 150 days prior to surveys (December 27, 2010 to May 25, 2011), and these above average temperatures extended to a depth of greater than 50 m. Our observations confirm that corals located on deeper, high latitude reefs are susceptible to thermal bleaching. Interestingly, at this location, C. marshae is close to the northern limit of its range (Veron and Marsh 1988), which may explain why it is more susceptible to thermal stress than the other species at Rottnest Island, most of which have distributions extending further north .

Biodiversity; coral reefs; South Africa. Southern African coral communities form a continuum from the more typical, accretive reefs in the tropics of Mozambique to the marginal, southernmost African distribution of this fauna in KwaZulu-Natal. While the latter are limited in size, they are gaining increasing attention as they provide a model for the study of many of the stresses to which these valuable systems are globally being subjected. Soft coral cover, comprising relatively few species, exceeds that of scleractinians over much of the southern reefs, and the coral communities attain a high biodiversity at this latitude on the East African coast. A long-term monitoring programme has revealed small yet significant changes in community structure on the reefs in recent years, concurrent with consistent increases in mean and maximum temperature. Insignificant bleaching was encountered during the 1998 ENSO event, unlike elsewhere in East Africa, but quantifiable bleaching occurred during an extended period of warming in 2000. Outbreaks of crown-of-thorns starfish (COTS) have caused longer-term changes in isolated areas. A study of coral larval dispersal and recruitment has been initiated to establish the capacity of the reefs to recover from the latter form of disturbance. The marginal nature of the reefs is further manifested by corals that generate aseasonal and atypical natural products and have a reproductive pattern that conforms with the pattern found on marginal reefs in western Australia. Calcium deposition on the reefs is also low due to physico-chemical factors that are related to latitude. Published projections on the long-term effects of climate change indicate that more reefs will become marginal as a result of global warming. Current monitoring on the South African reefs is being expanded to investigate the extent to which they will elucidate the future of more typical reefs.

Coral communities are found at high latitude on the East Coast subtropical reefs of South Africa. They are biodiverse, economically important, and afforded World Heritage Site status in the iSimangaliso Wetland Park where some are subjected to recreational use. While the Park's unique coral reefs have, to date, suffered little bleaching from climate change, they are susceptible to the phenomenon and provide a natural laboratory for the study of its effects at high latitude. This review covers recent advances in the regional oceanography; coral community dynamics and the underpinning reef processes, including minor bleaching events; the incidence of coral disease; and coral genetic connectivity. The effects of human activity (SCUBA diving, recreational fishing, pesticide use) were assessed, as well as the nursery benefits of Acropora austera, a coral which provides the reefs with much structure and is vulnerable to damage and climate change. The reefs were valued in terms of human use as well as services such as sediment generation and retention. The results have provided valuable information on relatively pristine, high-latitude reefs, their socio-economic benefits, and the anticipated effects of climate change.

Biodiversity; coral reefs; South Africa. Southern African coral communities form a continuum from the more typical, accretive reefs in the tropics of Mozambique to the marginal, southernmost African distribution of this fauna in KwaZulu-Natal. While the latter are limited in size, they are gaining increasing attention as they provide a model for the study of many of the stresses to which these valuable systems are globally being subjected. Soft coral cover, comprising relatively few species, exceeds that of scleractinians over much of the southern reefs, and the coral communities attain a high biodiversity at this latitude on the East African coast. A long-term monitoring programme has revealed small yet significant changes in community structure on the reefs in recent years, concurrent with consistent increases in mean and maximum temperature. Insignificant bleaching was encountered during the 1998 ENSO event, unlike elsewhere in East Africa, but quantifiable bleaching occurred during an extended period of warming in 2000. Outbreaks of crown-of-thorns starfish (COTS) have caused longer-term changes in isolated areas. A study of coral larval dispersal and recruitment has been initiated to establish the capacity of the reefs to recover from the latter form of disturbance. The marginal nature of the reefs is further manifested by corals that generate aseasonal and atypical natural products and have a reproductive pattern that conforms with the pattern found on marginal reefs in western Australia. Calcium deposition on the reefs is also low due to physico-chemical factors that are related to latitude. Published projections on the long-term effects of climate change indicate that more reefs will become marginal as a result of global warming. Current monitoring on the South African reefs is being expanded to investigate the extent to which they will elucidate the future of more typical reefs.

Significance Our study reveals a hitherto overlooked effect of warming on coral reefs. Traditionally, ecological studies of warming events focused on maximum temperatures and duration, rather than the rate of warming at the onset. Here, we show that onsets can trigger widespread mortality of reef fish. Hundreds of thermally stressed fish, belonging to dozens of species, became fatally infected with a common pathogen in the Red Sea. Differential susceptibility led to selective mortality, with disproportional death among predators and benthic feeders. A reassessment of past reports suggests that extreme onset might have been an overlooked trigger of fish kills elsewhere. Warming tropical and subtropical reefs may face an increasing frequency of extreme onsets, eliciting calamities far beyond coral bleaching.

The worlds' coral reefs are declining due to the combined effects of natural disturbances and anthropogenic pressures including thermal coral bleaching associated with global climate change. Nearshore corals are receiving increased anthropogenic stress from coastal development and nutrient run-off. Considering forecast increases in global temperatures, greater understanding of drivers of recovery on nearshore coral reefs following widespread bleaching events is required to inform management of local stressors. The west Pilbara coral reefs, with cross-shelf turbidity gradients coupled with a large nearby dredging program and recent history of repeated coral bleaching due to heat stress, represent an opportune location to study recovery from multiple disturbances. Mean coral cover at west Pilbara reefs was monitored from 2009 to 2018 and declined from 45% in 2009 to 5% in 2014 following three heat waves. Recruitment and juvenile abundance of corals were monitored from 2014 to 2018 and were combined with biological and physical data to identify which variables enhanced or hindered early-stage coral recovery of all hard corals and separately for the acroporids, the genera principally responsible for recovery in the short-term (<7 years). From 2014 to 2018, coral cover increased from 5 to 10% but recovery varied widely among sites (0-13%). Hard coral cover typically recovered most at shallower sites that had higher abundance of herbivorous fish, less macroalgae, and lower turbidity. Similarly, acroporid corals recovered most at sites with lower turbidity and macroalgal cover. Juvenile acroporid densities were a good indicator of recovery at least two years after they were recorded. However, recruitment to settlement tiles was not a good predictor of total coral or acroporid recovery. This study shows that coral recovery can be slower in areas of high turbidity and the rate may be reduced by local pressures, such as dredging. Management should focus on improving or maintaining local water quality to increase the likelihood of coral recovery under climate stress. Further, in turbid environments, juvenile coral density predicts early coral recovery better than recruits on tiles and may be a more cost-effective technique for monitoring recovery potential.

Recent studies indicate that the incidence and persistence of damage from coral reef bleaching are often highest in areas of restricted water motion, and that resistance to and recovery from bleaching is increased by enhanced water motion. We examined the hypothesis that water motion increases the efflux of oxygen from coral tissue thereby reducing oxidative stress on the photosynthetic apparatus of endosymbiotic zooxanthellae. We experimentally exposed colonies of Montastrea annularis and Agaricia agaricites to manipulations of water flow, light intensity, and oxygen concentration in the field using a novel mini-flume. We measured photosynthetic efficiency using a pulse amplitude modulated fluorometer to test the short-term response of corals to our manipulations. Under normal oxygen concentrations, A. agaricites showed a significant 8% increase in photosynthetic efficiency from 0.238 (± 0.032) in still water to 0.256 (± 0.037) in 15 cm s À1 flow, while M. annularis exhibited no detectable change. Under high-ambient oxygen concentrations, the observed effect of flow on A. agaricites was reversed: photosynthetic efficiencies showed a significant 11% decrease from 0.236 (± 0.056) in still water to 0.211 (± 0.048) in 15 cm s À1 flow. These results support the hypothesis that water motion helps to remove oxygen from coral tissues during periods of maximal photosynthesis. Flow mitigation of oxidative stress may at least partially explain the increased incidence and severity of coral bleaching in low flow areas and observations of enhanced recovery in high-flow areas.

La cartografía geomorfológica detallada permite entender cómo los procesos ecológicos claves se ven influenciados por el relieve submarino, además sirve para identificar sitios de interés particular donde se desarrollan hábitats bentónicos en áreas tropicales como la del Caribe central. El Parque Nacional Natural Corales de Profundidad fue declarado en 2013 como un área marina protegida en el mar Caribe colombiano. Se encuentra en el terreno tectónico Cinturón Plegado del Sinú, formado por la interacción entre la placa oceánica Caribe y la continental suramericana. Las características geológicas contribuyen a la comprensión del origen de las geoformas de fondo asociadas a diferentes ecosistemas en los que se encuentran corales de profundidad que, debido a su importancia ecológica, son comunidades bentónicas a
conservar. El modelo de elevación digital, elaborado con la información batimétrica adquirida con sistema multihaz, permitió la actualización e interpretación de unidades y rasgos geomorfológicos, utilizando como base el modelo de sombras para visualizar cambios abruptos y las
pendientes como atributos descriptivos de las unidades de relieve. En este trabajo se describen 16 unidades geomorfológicas con base en el modelo digital de terreno, las cuales fueron asociadas con posibles procesos de origen geológico como levantamiento, erosión, sedimentación y movimientos en masa, además de rasgos y lineamientos de tipo geomorfológico y geológico. Esta información contribuye a ampliar el conocimiento de los fondos marinos colombianos en los cuales se ha desarrollado poca investigación de este tipo.

En el extremo oriental del Pacífico Oriental Tropical se encuentra el arrecife de La Chola. Esta es una formación coralina de 11 ha de extensión, dominada por corales ramificados del género Pocillopora. El objetivo de este estudio fue evaluar los cambios en la cobertura coralina de este arrecife en el tiempo, mediante comparaciones entre datos tomados en 2002 y en 2013, usando transectos fijos. Adicionalmente, se generó un mapa actualizado de este arrecife, a partir de datos de campo tomados con un GPS, y se presentan los primeros datos de temperatura del agua. El arrecife experimentó una reducción cercana a 20% en la cobertura coralina viva durante el período evaluado, con un incremento en la cobertura de algas (principalmente algas coralinas). La extensión del arrecife parece haberse mantenido estable durante los últimos 30 años. Además de los tensores habituales asociados con las limitaciones en cobertura coralina de esta región del Pacífico, se proponen los descensos estacionales en la temperatura como potencial causa de las pérdidas de cobertura coralina en los sectores más profundos del arrecife.