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

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

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

F1000Research ◽

10.12688/f1000research.2-187.v2 ◽

2013 ◽

Vol 2 ◽

pp. 187 ◽

Cited By ~ 5

Author(s):

Tom C. L. Bridge ◽

Andrew S Hoey ◽

Stuart J Campbell ◽

Efin Muttaqin ◽

Edi Rudi ◽

...

Keyword(s):

Shallow Water ◽

Coral Bleaching ◽

Cold Water ◽

Depth Range ◽

Bleaching Event ◽

Sea Temperature ◽

Local Conditions ◽

Reef Corals ◽

Coral Communities ◽

High Conservation

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

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Outbreak and persistence of opportunistic symbiotic dinoflagellates during the 2005 Caribbean mass coral ‘bleaching’ event

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2009.1405 ◽

2009 ◽

Vol 276 (1676) ◽

pp. 4139-4148 ◽

Cited By ~ 153

Author(s):

Todd C. LaJeunesse ◽

Robin T. Smith ◽

Jennifer Finney ◽

Hazel Oxenford

Keyword(s):

Thermal Stress ◽

High Sensitivity ◽

Bleaching Event ◽

Reef Corals ◽

Ecological Benefit ◽

Evolutionary Response ◽

Symbiotic Dinoflagellates ◽

Extended Duration ◽

Coral Health ◽

First Time

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

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Tradeoffs to Thermal Acclimation: Energetics and Reproduction of a Reef Coral with Heat TolerantSymbiodiniumType-D

Journal of Marine Biology ◽

10.1155/2011/185890 ◽

2011 ◽

Vol 2011 ◽

pp. 1-12 ◽

Cited By ~ 63

Author(s):

Alison M. Jones ◽

Ray Berkelmans

Keyword(s):

Reef Coral ◽

Bleaching Event ◽

Larval Duration ◽

Negative Effects ◽

Broadcast Spawning ◽

Acropora Millepora ◽

Reef Corals ◽

Type D ◽

Tropical Reefs ◽

Spawning Time

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

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Homogenization of Endosymbiont Communities Hosted by Equatorial Corals during the 2016 Mass Bleaching Event

Microorganisms ◽

10.3390/microorganisms8091370 ◽

2020 ◽

Vol 8 (9) ◽

pp. 1370

Author(s):

Sudhanshi S. Jain ◽

Lutfi Afiq-Rosli ◽

Bar Feldman ◽

Oren Levy ◽

Jun Wei Phua ◽

...

Keyword(s):

Thermal Tolerance ◽

High Throughput Sequencing ◽

Quantitative Polymerase Chain Reaction ◽

Global Scale ◽

Bleaching Event ◽

Reef Corals ◽

Qpcr Method ◽

Polymerase Chain ◽

Limited Change

Thermal stress drives the bleaching of reef corals, during which the endosymbiotic relationship between Symbiodiniaceae microalgae and the host breaks down. The endosymbiont communities are known to shift in response to environmental disturbances, but how they respond within and between colonies during and following bleaching events remains unclear. In 2016, a major global-scale bleaching event hit countless tropical reefs. Here, we investigate the relative abundances of Cladocopium LaJeunesse & H.J.Jeong, 2018 and Durusdinium LaJeunesse, 2018 within and among Pachyseris speciosa colonies in equatorial Singapore that are known to host both these Symbiodiniaceae clades. Bleached and unbleached tissues from bleaching colonies, as well as healthy colonies, during and following the bleaching event were sampled and analyzed for comparison. The nuclear ribosomal internal transcribed spacer (ITS) regions were separately amplified and quantified using a SYBR Green-based quantitative polymerase chain reaction (qPCR) method and Illumina high-throughput sequencing. We found Cladocopium to be highly abundant relative to Durusdinium. The relative abundance of Durusdinium, known to be thermally tolerant, was highest in post-bleaching healthy colonies, while bleached and unbleached tissues from bleaching colonies as well as tissue from healthy colonies during the event had depressed proportions of Durusdinium. Given the importance of Durusdinium for thermal tolerance and stress response, it is surprising that bleached tissue showed limited change over healthy tissue during the bleaching event. Moreover, colonies were invariably dominated by Cladocopium during bleaching, but a minority of colonies were Durusdinium-dominant during non-bleaching times. The detailed characterization of Symbiodiniaceae in specific colonies during stress and recovery will provide insights into this crucial symbiosis, with implications for their responses during major bleaching events.

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Responses of urban reef corals during the 2016 mass bleaching event

Marine Pollution Bulletin ◽

10.1016/j.marpolbul.2020.111111 ◽

2020 ◽

Vol 154 ◽

pp. 111111 ◽

Cited By ~ 2

Author(s):

Chin Soon Lionel Ng ◽

Danwei Huang ◽

Kok Ben Toh ◽

Shu Qin Sam ◽

Yuichi Preslie Kikuzawa ◽

...

Keyword(s):

Bleaching Event ◽

Reef Corals ◽

Mass Bleaching Event ◽

Mass Bleaching

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

F1000Research ◽

10.12688/f1000research.2-187.v3 ◽

2014 ◽

Vol 2 ◽

pp. 187 ◽

Cited By ~ 13

Author(s):

Tom C. L. Bridge ◽

Andrew S Hoey ◽

Stuart J Campbell ◽

Efin Muttaqin ◽

Edi Rudi ◽

...

Keyword(s):

Shallow Water ◽

Coral Bleaching ◽

Cold Water ◽

Depth Range ◽

Bleaching Event ◽

Sea Temperature ◽

Local Conditions ◽

Reef Corals ◽

Coral Communities ◽

High Conservation

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

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Shifting Baselines: Physiological legacies contribute to the response of reef coral to frequent heat waves

10.1101/2020.04.23.056457 ◽

2020 ◽

Author(s):

Christopher B. Wall ◽

Contessa A. Ricci ◽

Alexandra D. Wen ◽

Bren E. Ledbetter ◽

Delania E. Klinger ◽

...

Keyword(s):

Environmental History ◽

Heat Waves ◽

Global Climate ◽

Abiotic Factors ◽

Reef Coral ◽

List Type ◽

Bleaching Event ◽

Reef Corals ◽

Legacy Effect ◽

Coral Reef Ecosystems

AbstractGlobal climate change is altering coral reef ecosystems. Notably, marine heat waves are producing widespread coral bleaching events that are increasing in frequency, with projections for annual bleaching events on reefs worldwide by mid-century.The response of corals to elevated seawater temperatures can be modulated by abiotic factors at site of origin and dominant endosymbiont type, which can result in a shift in multiple coral traits and drive physiological legacy effects that influence the trajectory of reef corals under subsequent thermal stress events. It is critical, therefore, to evaluate the potential for shifting physiological and cellular baselines driven by these factors in in situ bleaching (and recovery) events. Here, we use the back-to-back regional bleaching events of 2014 and 2015 in the Hawaiian Islands and subsequent recovery periods to test the hypothesis that coral multivariate trait space (here termed physiotype, sensu (Van Straalen, 2003) shift in multiple bleaching events, modulated by both environmental histories and symbiotic partnerships (Symbiodiniaceae).Despite fewer degree heating weeks in the first-bleaching event relative to the second (7 vs. 10), bleaching severity in a dominant reef building coral on Hawaiian reefs, Montipora capitata, was greater (~70% vs. 50% bleached cover) and differences due to environmental history (reef site) were more pronounced. Melanin, an immune cytotoxic response, provided an initial defense during the first event, potentially priming antioxidant activity, which peaked in the second-bleaching event (i.e., a legacy effect). While magnitude of bleaching differed, immune response patterns were shared among corals harboring heat-sensitive and heat-tolerant Symbiodiniaceae. This supports a pattern of increased constitutive immunity in corals resulting from repeat bleaching events, with greater specialized enzymes (catalase, peroxidase, superoxide dismutase) and attenuated melanin synthesis.This study demonstrates bleaching events have implications for reef corals beyond shaping their ecological assemblages. These events can change the magnitude and/or identity of response variables contributing to physiotype, thus generating physiological legacies carried over into the future. Quantifying baseline coral physiotypes and tracking their shifts will be critical to understanding and forecasting the effects of increased bleaching frequency on coral biology and ecology in the Anthropocene.

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