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Mellin C, Brown S, Cantin N, Klein-Salas E, Mouillot D, Heron SF, Fordham DA. Cumulative risk of future bleaching for the world's coral reefs. SCIENCE ADVANCES 2024; 10:eadn9660. [PMID: 38924396 PMCID: PMC11204209 DOI: 10.1126/sciadv.adn9660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 05/17/2024] [Indexed: 06/28/2024]
Abstract
Spatial and temporal patterns of future coral bleaching are uncertain, hampering global conservation efforts to protect coral reefs against climate change. Our analysis of daily projections of ocean warming establishes the severity, annual duration, and onset of severe bleaching risk for global coral reefs this century, pinpointing vital climatic refugia. We show that low-latitude coral regions are most vulnerable to thermal stress and will experience little reprieve from climate mitigation. By 2080, coral bleaching is likely to start on most reefs in spring, rather than late summer, with year-round bleaching risk anticipated to be high for some low-latitude reefs regardless of global efforts to mitigate harmful greenhouse gasses. By identifying Earth's reef regions that are at lowest risk of accelerated bleaching, our results will prioritize efforts to limit future loss of coral reef biodiversity.
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Affiliation(s)
- Camille Mellin
- The Environment Institute and School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Stuart Brown
- The Environment Institute and School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Neal Cantin
- Australian Institute of Marine Science, Townsville, QLD, Australia
| | | | - David Mouillot
- MARBEC, Univ Montpellier, CNRS, IFREMER, IRD, Montpellier, France
- Institut Universitaire de France, IUF, Paris 75231, France
| | - Scott F. Heron
- Physics and Marine Geophysical Laboratory, College of Science and Engineering, James Cook University, Townsville, QLD, Australia
| | - Damien A. Fordham
- The Environment Institute and School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
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2
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Strand EL, Wong KH, Farraj A, Gray S, McMenamin A, Putnam HM. Coral species-specific loss and physiological legacy effects are elicited by an extended marine heatwave. J Exp Biol 2024; 227:jeb246812. [PMID: 38774956 DOI: 10.1242/jeb.246812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 05/03/2024] [Indexed: 06/18/2024]
Abstract
Marine heatwaves are increasing in frequency and intensity, with potentially catastrophic consequences for marine ecosystems such as coral reefs. An extended heatwave and recovery time-series that incorporates multiple stressors and is environmentally realistic can provide enhanced predictive capacity for performance under climate change conditions. We exposed common reef-building corals in Hawai'i, Montipora capitata and Pocillopora acuta, to a 2-month period of high temperature and high PCO2 conditions or ambient conditions in a factorial design, followed by 2 months of ambient conditions. High temperature, rather than high PCO2, drove multivariate physiology shifts through time in both species, including decreases in respiration rates and endosymbiont densities. Pocillopora acuta exhibited more significantly negatively altered physiology, and substantially higher bleaching and mortality than M. capitata. The sensitivity of P. acuta appears to be driven by higher baseline rates of photosynthesis paired with lower host antioxidant capacity, creating an increased sensitivity to oxidative stress. Thermal tolerance of M. capitata may be partly due to harboring a mixture of Cladocopium and Durusdinium spp., whereas P. acuta was dominated by other distinct Cladocopium spp. Only M. capitata survived the experiment, but physiological state in heatwave-exposed M. capitata remained significantly diverged at the end of recovery relative to individuals that experienced ambient conditions. In future climate scenarios, particularly marine heatwaves, our results indicate a species-specific loss of corals that is driven by baseline host and symbiont physiological differences as well as Symbiodiniaceae community compositions, with the surviving species experiencing physiological legacies that are likely to influence future stress responses.
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Affiliation(s)
- Emma L Strand
- Department of Biology, University of Rhode Island, Kingston, RI 02881, USA
- Gloucester Marine Genomics Institute, Gloucester, MA 01930, USA
| | - Kevin H Wong
- Department of Biology, University of Rhode Island, Kingston, RI 02881, USA
- Department of Marine Biology and Ecology, University of Miami Rosenstiel School of Marine and Atmospheric Science, Miami, FL 33149, USA
| | - Alexa Farraj
- Department of Biology, University of Rhode Island, Kingston, RI 02881, USA
| | - Sierra Gray
- Department of Biology, University of Rhode Island, Kingston, RI 02881, USA
- Department of Biology, University of Victoria, Victoria, BC, Canada, V8P 5C2
| | - Ana McMenamin
- Department of Biology, University of Rhode Island, Kingston, RI 02881, USA
| | - Hollie M Putnam
- Department of Biology, University of Rhode Island, Kingston, RI 02881, USA
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3
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Helgoe J, Davy SK, Weis VM, Rodriguez-Lanetty M. Triggers, cascades, and endpoints: connecting the dots of coral bleaching mechanisms. Biol Rev Camb Philos Soc 2024; 99:715-752. [PMID: 38217089 DOI: 10.1111/brv.13042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 12/08/2023] [Accepted: 12/12/2023] [Indexed: 01/15/2024]
Abstract
The intracellular coral-dinoflagellate symbiosis is the engine that underpins the success of coral reefs, one of the most diverse ecosystems on the planet. However, the breakdown of the symbiosis and the loss of the microalgal symbiont (i.e. coral bleaching) due to environmental changes are resulting in the rapid degradation of coral reefs globally. There is an urgent need to understand the cellular physiology of coral bleaching at the mechanistic level to help develop solutions to mitigate the coral reef crisis. Here, at an unprecedented scope, we present novel models that integrate putative mechanisms of coral bleaching within a common framework according to the triggers (initiators of bleaching, e.g. heat, cold, light stress, hypoxia, hyposalinity), cascades (cellular pathways, e.g. photoinhibition, unfolded protein response, nitric oxide), and endpoints (mechanisms of symbiont loss, e.g. apoptosis, necrosis, exocytosis/vomocytosis). The models are supported by direct evidence from cnidarian systems, and indirectly through comparative evolutionary analyses from non-cnidarian systems. With this approach, new putative mechanisms have been established within and between cascades initiated by different bleaching triggers. In particular, the models provide new insights into the poorly understood connections between bleaching cascades and endpoints and highlight the role of a new mechanism of symbiont loss, i.e. 'symbiolysosomal digestion', which is different from symbiophagy. This review also increases the approachability of bleaching physiology for specialists and non-specialists by mapping the vast landscape of bleaching mechanisms in an atlas of comprehensible and detailed mechanistic models. We then discuss major knowledge gaps and how future research may improve the understanding of the connections between the diverse cascade of cellular pathways and the mechanisms of symbiont loss (endpoints).
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Affiliation(s)
- Joshua Helgoe
- Department of Biological Sciences, Institute of Environment, Florida International University, 11200 SW 8th Street, OE 167, Miami, FL, USA
| | - Simon K Davy
- School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand
| | - Virginia M Weis
- Department of Integrative Biology, Oregon State University, 2701 SW Campus Way, 2403 Cordley Hall, Corvallis, OR, USA
| | - Mauricio Rodriguez-Lanetty
- Department of Biological Sciences, Institute of Environment, Florida International University, 11200 SW 8th Street, OE 167, Miami, FL, USA
- Department of Biological Sciences, Biomolecular Sciences Institute, Florida International University, 11200 SW 8th Street, Miami, FL, USA
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4
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Edmunds PJ, Combosch DJ, Torrado H, Sakai K, Sinniger F, Burgess SC. Latitudinal variation in thermal performance of the common coral Pocillopora spp. J Exp Biol 2024; 227:jeb247090. [PMID: 38699869 DOI: 10.1242/jeb.247090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 04/26/2024] [Indexed: 05/05/2024]
Abstract
Understanding how tropical corals respond to temperatures is important to evaluating their capacity to persist in a warmer future. We studied the common Pacific coral Pocillopora over 44° of latitude, and used populations at three islands with different thermal regimes to compare their responses to temperature using thermal performance curves (TPCs) for respiration and gross photosynthesis. Corals were sampled in the local autumn from Moorea, Guam and Okinawa, where mean±s.d. annual seawater temperature is 28.0±0.9°C, 28.9±0.7°C and 25.1±3.4°C, respectively. TPCs for respiration were similar among latitudes, the thermal optimum (Topt) was above the local maximum temperature at all three islands, and maximum respiration was lowest at Okinawa. TPCs for gross photosynthesis were wider, implying greater thermal eurytopy, with a higher Topt in Moorea versus Guam and Okinawa. Topt was above the maximum temperature in Moorea, but was similar to daily temperatures over 13% of the year in Okinawa and 53% of the year in Guam. There was greater annual variation in daily temperatures in Okinawa than Guam or Moorea, which translated to large variation in the supply of metabolic energy and photosynthetically fixed carbon at higher latitudes. Despite these trends, the differences in TPCs for Pocillopora spp. were not profoundly different across latitudes, reducing the likelihood that populations of these corals could better match their phenotypes to future more extreme temperatures through migration. Any such response would place a premium on high metabolic plasticity and tolerance of large seasonal variations in energy budgets.
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Affiliation(s)
- P J Edmunds
- Department of Biology, California State University, Northridge, 18111 Nordhoff Street, Northridge, CA 91330-8303, USA
| | - D J Combosch
- Marine Laboratory, University of Guam, 303 University Drive, Mangilao, 96923 Guam, USA
| | - H Torrado
- Marine Laboratory, University of Guam, 303 University Drive, Mangilao, 96923 Guam, USA
| | - K Sakai
- Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, 3422 Sesoko, Motobu, 905-0227 Okinawa, Japan
| | - F Sinniger
- Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, 3422 Sesoko, Motobu, 905-0227 Okinawa, Japan
| | - S C Burgess
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
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Williams A. Multiomics data integration, limitations, and prospects to reveal the metabolic activity of the coral holobiont. FEMS Microbiol Ecol 2024; 100:fiae058. [PMID: 38653719 PMCID: PMC11067971 DOI: 10.1093/femsec/fiae058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 03/25/2024] [Accepted: 04/22/2024] [Indexed: 04/25/2024] Open
Abstract
Since their radiation in the Middle Triassic period ∼240 million years ago, stony corals have survived past climate fluctuations and five mass extinctions. Their long-term survival underscores the inherent resilience of corals, particularly when considering the nutrient-poor marine environments in which they have thrived. However, coral bleaching has emerged as a global threat to coral survival, requiring rapid advancements in coral research to understand holobiont stress responses and allow for interventions before extensive bleaching occurs. This review encompasses the potential, as well as the limits, of multiomics data applications when applied to the coral holobiont. Synopses for how different omics tools have been applied to date and their current restrictions are discussed, in addition to ways these restrictions may be overcome, such as recruiting new technology to studies, utilizing novel bioinformatics approaches, and generally integrating omics data. Lastly, this review presents considerations for the design of holobiont multiomics studies to support lab-to-field advancements of coral stress marker monitoring systems. Although much of the bleaching mechanism has eluded investigation to date, multiomic studies have already produced key findings regarding the holobiont's stress response, and have the potential to advance the field further.
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Affiliation(s)
- Amanda Williams
- Microbial Biology Graduate Program, Rutgers University, 76 Lipman Drive, New Brunswick, NJ 08901, United States
- Department of Biochemistry and Microbiology, Rutgers University, 76 Lipman Drive, New Brunswick, NJ 08901, United States
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Isa V, Seveso D, Diamante L, Montalbetti E, Montano S, Gobbato J, Lavorano S, Galli P, Louis YD. Physical and cellular impact of environmentally relevant microplastic exposure on thermally challenged Pocillopora damicornis (Cnidaria, Scleractinia). THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 918:170651. [PMID: 38320710 DOI: 10.1016/j.scitotenv.2024.170651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 01/18/2024] [Accepted: 02/01/2024] [Indexed: 02/13/2024]
Abstract
Microplastic pollution is an increasing threat to coral reefs, which are already strongly challenged by climate change-related heat stress. Although it is known that scleractinian corals can ingest microplastic, little is known about their egestion and how microplastic exposure may impair corals at physiological and cellular levels. In addition, the effects of microplastic pollution at current environmental concentration have been little investigated to date, particularly in corals already impacted by heat stress. In this study, the combined effects of these environmental threats on Pocillopora damicornis were investigated from a physical and cellular perspective. Colonies were exposed to three concentrations of polyethylene microplastic beads (no microplastic beads: [No MP], 1 mg/L: [Low MP]; 10 mg/L: [High MP]), and two different temperatures (25 °C and 30 °C) for 72 h. No visual signs of stress in corals, such as abnormal mucus production and polyp extroflection, were recorded. At [Low MP], beads adhered to colonies were ingested but were also egested. Moreover, thermally stressed colonies showed a lower adhesion and higher egestion of microplastic beads. Coral bleaching was observed with an increase in temperature and microplastic bead concentration, as indicated by a general decrease in chlorophyll concentration and Symbiodiniaceae density. An increase in lipid peroxidation was measured in colonies exposed to [Low MP] and [High MP] and an up-regulation of stress response gene hsp70 was observed due to the synergistic interaction of both stressors. Overall, our findings showed that heat stress still represents the main threat to P. damicornis, while the effect of microplastics on coral health and physiology may be minor, especially at control temperature. However, microplastics could exacerbate the effect of thermal stress on cellular homeostasis, even at [Low MP]. While reducing ocean warming is critical for preserving coral reefs, effective management of emerging threats like microplastic pollution is equally essential.
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Affiliation(s)
- Valerio Isa
- Department of Earth and Environmental Science, University of Milano Bicocca, Piazza della Scienza 1, 20126 Milano, Italy; MaRHE Center (Marine Research and High Education Center), Magoodhoo Island, Faafu Atoll, Maldives; Costa Edutainment SpA - Acquario di Genova, Area Porto Antico, Ponte Spinola, 16128 Genoa, Italy
| | - Davide Seveso
- Department of Earth and Environmental Science, University of Milano Bicocca, Piazza della Scienza 1, 20126 Milano, Italy; MaRHE Center (Marine Research and High Education Center), Magoodhoo Island, Faafu Atoll, Maldives
| | - Luca Diamante
- Department of Earth and Environmental Science, University of Milano Bicocca, Piazza della Scienza 1, 20126 Milano, Italy
| | - Enrico Montalbetti
- Department of Earth and Environmental Science, University of Milano Bicocca, Piazza della Scienza 1, 20126 Milano, Italy; MaRHE Center (Marine Research and High Education Center), Magoodhoo Island, Faafu Atoll, Maldives.
| | - Simone Montano
- Department of Earth and Environmental Science, University of Milano Bicocca, Piazza della Scienza 1, 20126 Milano, Italy; MaRHE Center (Marine Research and High Education Center), Magoodhoo Island, Faafu Atoll, Maldives
| | - Jacopo Gobbato
- Department of Earth and Environmental Science, University of Milano Bicocca, Piazza della Scienza 1, 20126 Milano, Italy; MaRHE Center (Marine Research and High Education Center), Magoodhoo Island, Faafu Atoll, Maldives
| | - Silvia Lavorano
- Costa Edutainment SpA - Acquario di Genova, Area Porto Antico, Ponte Spinola, 16128 Genoa, Italy
| | - Paolo Galli
- Department of Earth and Environmental Science, University of Milano Bicocca, Piazza della Scienza 1, 20126 Milano, Italy; MaRHE Center (Marine Research and High Education Center), Magoodhoo Island, Faafu Atoll, Maldives; University of Dubai, Dubai, P.O. Box 14143, United Arab Emirates
| | - Yohan Didier Louis
- Department of Earth and Environmental Science, University of Milano Bicocca, Piazza della Scienza 1, 20126 Milano, Italy; MaRHE Center (Marine Research and High Education Center), Magoodhoo Island, Faafu Atoll, Maldives
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Jia S, Geng X, Cai Z, Wang Y, Shen J, Li Y, Wu Z, Chen S, Wang D. Comparison of physiological and transcriptome responses of corals to strong light and high temperature. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 273:116143. [PMID: 38430582 DOI: 10.1016/j.ecoenv.2024.116143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 02/17/2024] [Accepted: 02/20/2024] [Indexed: 03/04/2024]
Abstract
Coral reefs are essential for marine ecology and biodiversity. Global climate change has resulted in severe coral reef degradation, partly via coral bleaching, which is caused by rising sea temperatures and solar light intensity. In this study, we examined the impact of strong light (300 µmol.m-2.s-1) and high temperature (33°C) on the growth, immunity, and gene expression of Galaxea fascicularis. Strong light caused coral bleaching in the absence of high sea temperatures, while no obvious bleaching was observed under high temperature alone. The effect of strong light on calcification rate of G. fascicularis is significantly weaker than that of high temperature. Both strong light and high temperatures significantly affected the immune enzyme activity of G. fascicularis symbionts, with the former having a strong effect on their photosystem. Temperature affected the digestive system, replication and repair, and cell growth and death of coral hosts, as indicated by transcriptomics analysis. These results provide a valuable for strategies to mitigate coral bleaching. TEASER: We explored the effects of strong light exposure and high temperature on coral reefs and their symbiont algae.
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Affiliation(s)
- Shuwen Jia
- Hainan Academy of Ocean and Fisheries Sciences, Haikou 571136, China; Key Laboratory for Coastal Marine Eco-Environment Process and Carbon Sink of Hainan province, Yazhou Bay Innovation Institute, College of Ecology and Environment, Hainan Tropical Ocean University, Sanya 572000, China; Key laboratory of Utilization and Conservation for Tropical Marine Bioresources (Hainan Tropical Ocean University), Ministry of Education, Sanya 572022, China
| | - Xiaoxiao Geng
- Hainan Academy of Ocean and Fisheries Sciences, Haikou 571136, China; Key Laboratory for Coastal Marine Eco-Environment Process and Carbon Sink of Hainan province, Yazhou Bay Innovation Institute, College of Ecology and Environment, Hainan Tropical Ocean University, Sanya 572000, China; Key laboratory of Utilization and Conservation for Tropical Marine Bioresources (Hainan Tropical Ocean University), Ministry of Education, Sanya 572022, China
| | - Zefu Cai
- Hainan Academy of Ocean and Fisheries Sciences, Haikou 571136, China; Key Laboratory for Coastal Marine Eco-Environment Process and Carbon Sink of Hainan province, Yazhou Bay Innovation Institute, College of Ecology and Environment, Hainan Tropical Ocean University, Sanya 572000, China; Key laboratory of Utilization and Conservation for Tropical Marine Bioresources (Hainan Tropical Ocean University), Ministry of Education, Sanya 572022, China
| | - Yi Wang
- Hainan Academy of Ocean and Fisheries Sciences, Haikou 571136, China; Key Laboratory for Coastal Marine Eco-Environment Process and Carbon Sink of Hainan province, Yazhou Bay Innovation Institute, College of Ecology and Environment, Hainan Tropical Ocean University, Sanya 572000, China; Key laboratory of Utilization and Conservation for Tropical Marine Bioresources (Hainan Tropical Ocean University), Ministry of Education, Sanya 572022, China
| | - Jie Shen
- Hainan Academy of Ocean and Fisheries Sciences, Haikou 571136, China; Key Laboratory for Coastal Marine Eco-Environment Process and Carbon Sink of Hainan province, Yazhou Bay Innovation Institute, College of Ecology and Environment, Hainan Tropical Ocean University, Sanya 572000, China; Key laboratory of Utilization and Conservation for Tropical Marine Bioresources (Hainan Tropical Ocean University), Ministry of Education, Sanya 572022, China
| | - Yuanchao Li
- Hainan Academy of Ocean and Fisheries Sciences, Haikou 571136, China; Key Laboratory for Coastal Marine Eco-Environment Process and Carbon Sink of Hainan province, Yazhou Bay Innovation Institute, College of Ecology and Environment, Hainan Tropical Ocean University, Sanya 572000, China; Key laboratory of Utilization and Conservation for Tropical Marine Bioresources (Hainan Tropical Ocean University), Ministry of Education, Sanya 572022, China
| | - Zhongjie Wu
- Hainan Academy of Ocean and Fisheries Sciences, Haikou 571136, China; Key Laboratory for Coastal Marine Eco-Environment Process and Carbon Sink of Hainan province, Yazhou Bay Innovation Institute, College of Ecology and Environment, Hainan Tropical Ocean University, Sanya 572000, China; Key laboratory of Utilization and Conservation for Tropical Marine Bioresources (Hainan Tropical Ocean University), Ministry of Education, Sanya 572022, China
| | - Shiquan Chen
- Hainan Academy of Ocean and Fisheries Sciences, Haikou 571136, China; Key Laboratory for Coastal Marine Eco-Environment Process and Carbon Sink of Hainan province, Yazhou Bay Innovation Institute, College of Ecology and Environment, Hainan Tropical Ocean University, Sanya 572000, China; Key laboratory of Utilization and Conservation for Tropical Marine Bioresources (Hainan Tropical Ocean University), Ministry of Education, Sanya 572022, China.
| | - Daoru Wang
- Hainan Academy of Ocean and Fisheries Sciences, Haikou 571136, China; Key Laboratory for Coastal Marine Eco-Environment Process and Carbon Sink of Hainan province, Yazhou Bay Innovation Institute, College of Ecology and Environment, Hainan Tropical Ocean University, Sanya 572000, China; Key laboratory of Utilization and Conservation for Tropical Marine Bioresources (Hainan Tropical Ocean University), Ministry of Education, Sanya 572022, China.
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Quigley KM. Breeding and Selecting Corals Resilient to Global Warming. Annu Rev Anim Biosci 2024; 12:209-332. [PMID: 37931139 DOI: 10.1146/annurev-animal-021122-093315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
Selective breeding of resilient organisms is an emerging topic in marine conservation. It can help us predict how species will adapt in the future and how we can help restore struggling populations effectively in the present. Scleractinian corals represent a potential tractable model system given their widescale phenotypic plasticity across fitness-related traits and a reproductive life history based on mass synchronized spawning. Here, I explore the justification for breeding in corals, identify underutilized pathways of acclimation, and highlight avenues for quantitative targeted breeding from the coral host and symbiont perspective. Specifically, the facilitation of enhanced heat tolerance by targeted breeding of plasticity mechanisms is underutilized. Evidence from theoretical genetics identifies potential pitfalls, including inattention to physical and genetic characteristics of the receiving environment. Three criteria for breeding emerge from this synthesis: selection from warm, variable reefs that have survived disturbance. This information will be essential to protect what we have and restore what we can.
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Affiliation(s)
- K M Quigley
- The Minderoo Foundation, Perth, Western Australia, Australia;
- James Cook University, Townsville, Queensland, Australia
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9
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Walker AS, Kratochwill CA, van Woesik R. Past disturbances and local conditions influence the recovery rates of coral reefs. GLOBAL CHANGE BIOLOGY 2024; 30:e17112. [PMID: 38273580 DOI: 10.1111/gcb.17112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 11/28/2023] [Accepted: 11/28/2023] [Indexed: 01/27/2024]
Abstract
Corals are being increasingly subjected to marine heatwaves. Theory suggests that increasing the intensity of disturbances reduces recovery rates, which inspired us to examine the recovery rates of coral cover following marine heatwaves, cyclones, and other disturbances at 1921 study sites, in 58 countries and three oceans, from 1977 to 2020. In the Atlantic Ocean, coral cover has decreased fourfold since the 1970s, and recovery rates following disturbances have been relatively slow, except in the Antilles. By contrast, reefs in the Pacific and Indian Oceans have maintained coral cover and recovery rates over time. There were positive relationships between rates of coral recovery and prior cyclone and heatwave frequency, and negative relationships between rates of coral recovery and macroalgae cover and distance to shore. A recent increase in the variance in recovery rates in some ecoregions of the Pacific and Indian Oceans suggests that some reefs in those ecoregions may be approaching a phase shift. While marine heatwaves are increasing in intensity and frequency, our results suggest that regional and local conditions influence coral recovery rates, and therefore, effective local management efforts can help reefs recover from disturbances.
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Affiliation(s)
- Andrew S Walker
- Institute for Global Ecology, Florida Institute of Technology, Melbourne, Florida, USA
| | - Chelsey A Kratochwill
- Institute for Global Ecology, Florida Institute of Technology, Melbourne, Florida, USA
| | - Robert van Woesik
- Institute for Global Ecology, Florida Institute of Technology, Melbourne, Florida, USA
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10
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Brown KT, Lenz EA, Glass BH, Kruse E, McClintock R, Drury C, Nelson CE, Putnam HM, Barott KL. Divergent bleaching and recovery trajectories in reef-building corals following a decade of successive marine heatwaves. Proc Natl Acad Sci U S A 2023; 120:e2312104120. [PMID: 38113265 PMCID: PMC10756270 DOI: 10.1073/pnas.2312104120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 11/17/2023] [Indexed: 12/21/2023] Open
Abstract
Increasingly frequent marine heatwaves are devastating coral reefs. Corals that survive these extreme events must rapidly recover if they are to withstand subsequent events, and long-term survival in the face of rising ocean temperatures may hinge on recovery capacity and acclimatory gains in heat tolerance over an individual's lifespan. To better understand coral recovery trajectories in the face of successive marine heatwaves, we monitored the responses of bleaching-susceptible and bleaching-resistant individuals of two dominant coral species in Hawai'i, Montipora capitata and Porites compressa, over a decade that included three marine heatwaves. Bleaching-susceptible colonies of P. compressa exhibited beneficial acclimatization to heat stress (i.e., less bleaching) following repeat heatwaves, becoming indistinguishable from bleaching-resistant conspecifics during the third heatwave. In contrast, bleaching-susceptible M. capitata repeatedly bleached during all successive heatwaves and exhibited seasonal bleaching and substantial mortality for up to 3 y following the third heatwave. Encouragingly, bleaching-resistant individuals of both species remained pigmented across the entire time series; however, pigmentation did not necessarily indicate physiological resilience. Specifically, M. capitata displayed incremental yet only partial recovery of symbiont density and tissue biomass across both bleaching phenotypes up to 35 mo following the third heatwave as well as considerable partial mortality. Conversely, P. compressa appeared to recover across most physiological metrics within 2 y and experienced little to no mortality. Ultimately, these results indicate that even some visually robust, bleaching-resistant corals can carry the cost of recurring heatwaves over multiple years, leading to divergent recovery trajectories that may erode coral reef resilience in the Anthropocene.
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Affiliation(s)
- Kristen T. Brown
- Department of Biology, University of Pennsylvania, Philadelphia, PA19104
| | - Elizabeth A. Lenz
- University of Hawai’i Sea Grant College Program, University of Hawai’i at Mānoa, Honolulu, HI96822
| | - Benjamin H. Glass
- Department of Biology, University of Pennsylvania, Philadelphia, PA19104
| | - Elisa Kruse
- Department of Biology, University of Pennsylvania, Philadelphia, PA19104
| | - Rayna McClintock
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, Department of Oceanography, University of Hawai’i at Mānoa, Honolulu, HI96822
| | - Crawford Drury
- Hawai’i Institute of Marine Biology, University of Hawai’i at Mānoa, Kāne‘ohe, HI96744
| | - Craig E. Nelson
- University of Hawai’i Sea Grant College Program, University of Hawai’i at Mānoa, Honolulu, HI96822
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, Department of Oceanography, University of Hawai’i at Mānoa, Honolulu, HI96822
| | - Hollie M. Putnam
- Department of Biological Sciences, University of Rhode Island, Kingston, RI02881
| | - Katie L. Barott
- Department of Biology, University of Pennsylvania, Philadelphia, PA19104
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11
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Khen A, Wall CB, Smith JE. Standardization of in situ coral bleaching measurements highlights the variability in responses across genera, morphologies, and regions. PeerJ 2023; 11:e16100. [PMID: 37810774 PMCID: PMC10552771 DOI: 10.7717/peerj.16100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 08/25/2023] [Indexed: 10/10/2023] Open
Abstract
Marine heatwaves and regional coral bleaching events have become more frequent and severe across the world's oceans over the last several decades due to global climate change. Observational studies have documented spatiotemporal variation in the responses of reef-building corals to thermal stress within and among taxa across geographic scales. Although many tools exist for predicting, detecting, and quantifying coral bleaching, it remains difficult to compare bleaching severity (e.g., percent cover of bleached surface areas) among studies and across species or regions. For this review, we compiled over 2,100 in situ coral bleaching observations representing 87 reef-building coral genera and 250 species of common morphological groups from a total of 74 peer-reviewed scientific articles, encompassing three broad geographic regions (Atlantic, Indian, and Pacific Oceans). While bleaching severity was found to vary by region, genus, and morphology, we found that both genera and morphologies responded differently to thermal stress across regions. These patterns were complicated by (i) inconsistent methods and response metrics across studies; (ii) differing ecological scales of observations (i.e., individual colony-level vs. population or community-level); and (iii) temporal variability in surveys with respect to the onset of thermal stress and the chronology of bleaching episodes. To improve cross-study comparisons, we recommend that future surveys prioritize measuring bleaching in the same individual coral colonies over time and incorporate the severity and timing of warming into their analyses. By reevaluating and standardizing the ways in which coral bleaching is quantified, researchers will be able to track responses to marine heatwaves with increased rigor, precision, and accuracy.
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Affiliation(s)
- Adi Khen
- Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, United States of America
| | - Christopher B. Wall
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, United States of America
| | - Jennifer E. Smith
- Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, United States of America
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12
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Dellaert Z, Putnam HM. Reconciling the variability in the biological response of marine invertebrates to climate change. J Exp Biol 2023; 226:jeb245834. [PMID: 37655544 DOI: 10.1242/jeb.245834] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
As climate change increases the rate of environmental change and the frequency and intensity of disturbance events, selective forces intensify. However, given the complicated interplay between plasticity and selection for ecological - and thus evolutionary - outcomes, understanding the proximate signals, molecular mechanisms and the role of environmental history becomes increasingly critical for eco-evolutionary forecasting. To enhance the accuracy of our forecasting, we must characterize environmental signals at a level of resolution that is relevant to the organism, such as the microhabitat it inhabits and its intracellular conditions, while also quantifying the biological responses to these signals in the appropriate cells and tissues. In this Commentary, we provide historical context to some of the long-standing challenges in global change biology that constrain our capacity for eco-evolutionary forecasting using reef-building corals as a focal model. We then describe examples of mismatches between the scales of external signals relative to the sensors and signal transduction cascades that initiate and maintain cellular responses. Studying cellular responses at this scale is crucial because these responses are the basis of acclimation to changing environmental conditions and the potential for environmental 'memory' of prior or historical conditions through molecular mechanisms. To challenge the field, we outline some unresolved questions and suggest approaches to align experimental work with an organism's perception of the environment; these aspects are discussed with respect to human interventions.
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Affiliation(s)
- Zoe Dellaert
- Department of Biological Sciences, University of Rhode Island, 120 Flagg Rd, Kingston, RI 02881, USA
| | - Hollie M Putnam
- Department of Biological Sciences, University of Rhode Island, 120 Flagg Rd, Kingston, RI 02881, USA
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13
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Glass BH, Ashey J, Okongwu AR, Putnam HM, Barott KL. Characterization of a sperm motility signalling pathway in a gonochoric coral suggests conservation across cnidarian sexual systems. Proc Biol Sci 2023; 290:20230085. [PMID: 37528706 PMCID: PMC10394420 DOI: 10.1098/rspb.2023.0085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 07/10/2023] [Indexed: 08/03/2023] Open
Abstract
Most stony corals liberate their gametes into the water column via broadcast spawning, where fertilization hinges upon the activation of directional sperm motility. Sperm from gonochoric and hermaphroditic corals display distinct morphological and molecular phenotypes, yet it is unknown whether the signalling pathways controlling sperm motility are also distinct between these sexual systems. Here, we addressed this knowledge gap using the gonochoric, broadcast spawning coral Astrangia poculata. We found that cytosolic alkalinization of sperm activates the pH-sensing enzyme soluble adenylyl cyclase (sAC), which is required for motility. Additionally, we demonstrate for the first time in any cnidarian that sAC activity leads to protein kinase A (PKA) activation, and that PKA activity contributes to sperm motility activation. Ultrastructures of A. poculata sperm displayed morphological homology with other gonochoric cnidarians, and sAC exhibited broad structural and functional conservation across this phylum. These results indicate a conserved role for pH-dependent sAC-cAMP-PKA signalling in sperm motility across coral sexual systems, and suggest that the role of this pathway in sperm motility may be ancestral in metazoans. Finally, the dynamics of this pH-sensitive pathway may play a critical role in determining the sensitivity of marine invertebrate reproduction to anthropogenic ocean acidification.
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Affiliation(s)
- Benjamin H. Glass
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jill Ashey
- Department of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA
| | | | - Hollie M. Putnam
- Department of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA
| | - Katie L. Barott
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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14
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Shlesinger T, van Woesik R. Oceanic differences in coral-bleaching responses to marine heatwaves. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 871:162113. [PMID: 36773903 DOI: 10.1016/j.scitotenv.2023.162113] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 02/02/2023] [Accepted: 02/04/2023] [Indexed: 06/18/2023]
Abstract
Anomalously high ocean temperatures have increased in frequency, intensity, and duration over the last several decades because of greenhouse gas emissions that cause global warming and marine heatwaves. Reef-building corals are sensitive to such temperature anomalies that commonly lead to coral bleaching, mortality, and changes in community structure. Yet, despite these overarching effects, there are geographical differences in thermal regimes, evolutionary histories, and past disturbances that may lead to different bleaching responses of corals within and among oceans. Here we examined the overall bleaching responses of corals in the Atlantic, Indian, and Pacific Oceans, using both a spatially explicit Bayesian mixed-effects model and a deep-learning neural-network model. We used a 40-year global dataset encompassing 23,288 coral-reef surveys at 11,058 sites in 88 countries, from 1980 to 2020. Focusing on ocean-wide differences we assessed the relationships between the percentage of bleached corals and different temperature-related metrics alongside a suite of environmental variables. We found that while high sea-surface temperatures were consistently, and strongly, related to coral bleaching within all oceans, there were clear geographical differences in the relationships between coral bleaching and most environmental variables. For instance, there was an increase in coral bleaching with depth in the Atlantic Ocean whereas the opposite was observed in the Indian Ocean, and no clear trend could be seen in the Pacific Ocean. The standard deviation of thermal-stress anomalies was negatively related to coral bleaching in the Atlantic and Pacific Oceans, but not in the Indian Ocean. Globally, coral bleaching has progressively occurred at higher temperatures over the last four decades within the Atlantic, Indian, and Pacific Oceans, although, again, there were differences among the three oceans. Together, such patterns highlight that historical circumstances and geographical differences in oceanographic conditions play a central role in contemporary coral-bleaching responses.
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Affiliation(s)
- Tom Shlesinger
- Institute for Global Ecology, Florida Institute of Technology, Melbourne 32901, FL, USA
| | - Robert van Woesik
- Institute for Global Ecology, Florida Institute of Technology, Melbourne 32901, FL, USA.
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15
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Symbiotic dinoflagellates divert energy away from mutualism during coral bleaching recovery. Symbiosis 2023. [DOI: 10.1007/s13199-023-00901-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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16
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Similarities in biomass and energy reserves among coral colonies from contrasting reef environments. Sci Rep 2023; 13:1355. [PMID: 36693980 PMCID: PMC9873650 DOI: 10.1038/s41598-023-28289-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 01/16/2023] [Indexed: 01/26/2023] Open
Abstract
Coral reefs are declining worldwide, yet some coral populations are better adapted to withstand reductions in pH and the rising frequency of marine heatwaves. The nearshore reef habitats of Palau, Micronesia are a proxy for a future of warmer, more acidic oceans. Coral populations in these habitats can resist, and recover from, episodes of thermal stress better than offshore conspecifics. To explore the physiological basis of this tolerance, we compared tissue biomass (ash-free dry weight cm-2), energy reserves (i.e., protein, total lipid, carbohydrate content), and several important lipid classes in six coral species living in both offshore and nearshore environments. In contrast to expectations, a trend emerged of many nearshore colonies exhibiting lower biomass and energy reserves than colonies from offshore sites, which may be explained by the increased metabolic demand of living in a warmer, acidic, environment. Despite hosting different dinoflagellate symbiont species and having access to contrasting prey abundances, total lipid and lipid class compositions were similar in colonies from each habitat. Ultimately, while the regulation of colony biomass and energy reserves may be influenced by factors, including the identity of the resident symbiont, kind of food consumed, and host genetic attributes, these independent processes converged to a similar homeostatic set point under different environmental conditions.
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17
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Assessing the Trophic Impact of Bleaching: The Model Pair Berghia stephanieae/ Exaiptasia diaphana. Animals (Basel) 2023; 13:ani13020291. [PMID: 36670832 PMCID: PMC9854479 DOI: 10.3390/ani13020291] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 01/18/2023] Open
Abstract
Bleaching events associated with climate change are increasing worldwide, being a major threat to tropical coral reefs. Nonetheless, the indirect impacts promoted by the bleaching of organisms hosting photosynthetic endosymbionts, such as those impacting trophic interactions, have received considerably less attention by the scientific community. Bleaching significantly affects the nutritional quality of bleached organisms. The consequences promoted by such shifts remain largely overlooked, namely on specialized predators that have evolved to prey upon organisms hosting photosynthetic endosymbionts and benefit nutritionally, either directly or indirectly, from the available pool of photosynthates. In the present study, we advocate the use of the model predator-prey pair featuring the stenophagous nudibranch sea slug Berghia stephanieae that preys upon the photosymbiotic glass anemone Exaiptasia diaphana to study the impacts of bleaching on trophic interactions. These model organisms are already used in other research fields, and one may benefit from knowledge available on their physiology, omics, and culture protocols under controlled laboratory conditions. Moreover, B. stephanieae can thrive on either photosymbiotic or aposymbiotic (bleached) glass anemones, which can be easily maintained over long periods in the laboratory (unlike photosymbiotic corals). As such, one can investigate if and how nutritional shifts induced by bleaching impact highly specialized predators (stenophagous species), as well as if and how such effects cascade over consecutive generations. Overall, by using this model predator-prey pair one can start to truly unravel the trophic effects of bleaching events impacting coral reef communities, as well as their prevalence over time.
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18
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Brown KT, Barott KL. The Costs and Benefits of Environmental Memory for Reef-Building Corals Coping with Recurring Marine Heatwaves. Integr Comp Biol 2022; 62:1748-1755. [PMID: 35661887 DOI: 10.1093/icb/icac074] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/25/2022] [Accepted: 05/31/2022] [Indexed: 01/05/2023] Open
Abstract
Marine heatwaves are occurring more frequently as climate change intensifies, resulting in global mass coral bleaching events several times per decade. Despite the time between marine heatwaves decreasing, there is evidence that reef-building corals can develop increased bleaching resistance across repetitive marine heatwaves. This phenomenon of acclimatization via environmental memory may be an important strategy to ensure coral persistence; however, we still understand very little about the apparent acclimatization or, conversely, sensitization (i.e., stress accumulation or weakening) of reef-building corals to consecutive heatwaves and its implications for the trajectory and resilience of coral reefs. Here, we highlight that not only will some corals become stress hardened via marine heatwaves, but many other individuals will suffer sensitization during repeat heatwaves that further exacerbates their stress response during repeat events and depresses fitness. Under current and predicted climate change, it is necessary to gain a better understanding of the acclimatization vs. sensitization trajectories of different species and individuals on the reef, as well as identify whether changes in bleaching susceptibility relates to physiological acclimatization, trade-offs with other biological processes, and ultimately coral persistence in the Anthropocene.
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Affiliation(s)
- Kristen T Brown
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.,School of Biological Sciences, University of Queensland, St. Lucia , QLD 4072, Australia
| | - Katie L Barott
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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19
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Keshavmurthy S, Chen TR, Liu PJ, Wang JT, Chen CA. Learning from the past is not enough to survive present and future bleaching threshold temperatures. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 852:158379. [PMID: 36055494 DOI: 10.1016/j.scitotenv.2022.158379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 06/15/2023]
Abstract
In the past decade, the frequency of mass coral bleaching events has increased due to seawater temperature anomalies persisting for longer periods. Coral survival from temperature anomalies has been based on how each species in each location responds to stress, which is unique to individual species and may be due to the way stressful experiences accumulate through time in the form of ecological and physiological memory. A deeper understanding of ecological and physiological memory in corals is necessary to understand their survival strategies into the future. Laboratory experiments can help us simulate seawater temperatures experienced by corals in the past and compare their responses to those of the present and future. In this study, we sampled corals with different life history traits from one location perturbed by seawater temperature incursions (variable site) and from a second, relatively undisturbed location (stable site). We sampled across two seasons to observe the responses to bleaching threshold temperatures in the past (1998-29 °C), present (2018-31 °C), and future (2050-33 °C). Corals were healthy at 29 °C and 31 °C, but a fast-growing, temperature-susceptible coral species experienced high mortality at 33 °C compared to a slow-growing, temperature-resistant coral species. Moreover, corals from the variable site and during the spring season fared better under temperature stress. The results of this study provide insight into the possible role of life-history traits on coral's response to seasons and locations in terms of memory to long-term and short-term thermal anomalies and climate change.
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Affiliation(s)
| | - Ting-Ru Chen
- Biodiversity Research Centre, Academia Sinica, Nangang, Taipei 115, Taiwan; Institute of Oceanography, National Taiwan University, Taipei 106, Taiwan
| | - Pei-Jen Liu
- Institute of Marine Biology, National Dong Hwa University, Hualien 974, Taiwan
| | - Jih-Terng Wang
- Department of Oceanography, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Chaolun Allen Chen
- Biodiversity Research Centre, Academia Sinica, Nangang, Taipei 115, Taiwan; Department of Life Science, National Taiwan Normal University, Taipei 106, Taiwan; Department of Life Science, Tunghai University, Taichung 404, Taiwan.
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20
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Brown KT, Eyal G, Dove SG, Barott KL. Fine-scale heterogeneity reveals disproportionate thermal stress and coral mortality in thermally variable reef habitats during a marine heatwave. CORAL REEFS (ONLINE) 2022; 42:131-142. [PMID: 36415309 PMCID: PMC9672654 DOI: 10.1007/s00338-022-02328-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 11/05/2022] [Indexed: 06/16/2023]
Abstract
UNLABELLED Increasing ocean temperatures threaten coral reefs globally, but corals residing in habitats that experience high thermal variability are thought to be better adapted to survive climate-induced heat stress. Here, we used long-term ecological observations and in situ temperature data from Heron Island, southern Great Barrier Reef to investigate how temperature dynamics within various thermally variable vs. thermally stable reef habitats change during a marine heatwave and the resulting consequences for coral community survival. During the heatwave, thermally variable habitats experienced larger surges in daily mean and maxima temperatures compared to stable sites, including extreme hourly incursions up to 36.5 °C. The disproportionate increase in heat stress in variable habitats corresponded with greater subsequent declines in hard coral cover, including a three-times greater decline within the thermally variable Reef Flat (70%) and Deep Lagoon (83%) than within thermally stable habitats along sheltered and exposed areas of the reef slope (0.3-19%). Interestingly, the thermally variable Reef Crest experienced comparatively small declines (26%), avoiding the most severe tidal ponding and resultant heat stress likely due to proximity to the open ocean equating to lower seawater residence times, greater mixing, and/or increased flow. These results highlight that variable thermal regimes, and any acclimatization or adaptation to elevated temperatures that may lead to, do not necessarily equate to protection against bleaching and mortality during marine heatwaves. Instead, thermally stable habitats that have greater seawater exchange with the open ocean may offer the most protection to corals during the severe marine heatwaves that accompany a changing climate. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s00338-022-02328-6.
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Affiliation(s)
- Kristen T. Brown
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104 USA
- School of Biological Sciences and ARC Centre of Excellence for Coral Reef Studies, University of Queensland, St. Lucia, QLD 4072 Australia
| | - Gal Eyal
- School of Biological Sciences and ARC Centre of Excellence for Coral Reef Studies, University of Queensland, St. Lucia, QLD 4072 Australia
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, 5290002 Ramat Gan, Israel
| | - Sophie G. Dove
- School of Biological Sciences and ARC Centre of Excellence for Coral Reef Studies, University of Queensland, St. Lucia, QLD 4072 Australia
| | - Katie L. Barott
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104 USA
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21
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Alderdice R, Perna G, Cárdenas A, Hume BCC, Wolf M, Kühl M, Pernice M, Suggett DJ, Voolstra CR. Deoxygenation lowers the thermal threshold of coral bleaching. Sci Rep 2022; 12:18273. [PMID: 36316371 PMCID: PMC9622859 DOI: 10.1038/s41598-022-22604-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/17/2022] [Indexed: 12/02/2022] Open
Abstract
Exposure to deoxygenation from climate warming and pollution is emerging as a contributing factor of coral bleaching and mortality. However, the combined effects of heating and deoxygenation on bleaching susceptibility remain unknown. Here, we employed short-term thermal stress assays to show that deoxygenated seawater can lower the thermal limit of an Acropora coral by as much as 1 °C or 0.4 °C based on bleaching index scores or dark-acclimated photosynthetic efficiencies, respectively. Using RNA-Seq, we show similar stress responses to heat with and without deoxygenated seawater, both activating putative key genes of the hypoxia-inducible factor response system indicative of cellular hypoxia. We also detect distinct deoxygenation responses, including a disruption of O2-dependent photo-reception/-protection, redox status, and activation of an immune response prior to the onset of bleaching. Thus, corals are even more vulnerable when faced with heat stress in deoxygenated waters. This highlights the need to integrate dissolved O2 measurements into global monitoring programs of coral reefs.
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Affiliation(s)
- Rachel Alderdice
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia.
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany.
| | - Gabriela Perna
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Anny Cárdenas
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Benjamin C C Hume
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Martin Wolf
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Michael Kühl
- Marine Biology Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000, Helsingør, Denmark
| | - Mathieu Pernice
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - David J Suggett
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia
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