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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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Angeles-Gonzalez LE, Torrejón-Magallanes J, Escamilla-Aké A, Osorio-Olvera L, Avendaño O, Díaz F, Rosas C. Can upwelling regions be potential thermal refugia for marine fishes during climate warming? J Therm Biol 2024; 123:103893. [PMID: 38924931 DOI: 10.1016/j.jtherbio.2024.103893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 05/29/2024] [Accepted: 06/06/2024] [Indexed: 06/28/2024]
Abstract
Species are expected to migrate to higher latitudes as warming intensifies due to anthropogenic climate change since physiological mechanisms have been adapted to maximize fitness under specific temperatures. However, literature suggests that upwellings could act as thermal refugia under climate warming protecting marine ecosystem diversity. This research aimed to predict the effects of climate warming on commercial and non-commercial fish species reported in official Mexican documents (>200 species) based on their thermal niche to observe if upwellings can act as potential thermal refugia. Present (2000-2014) and Representative Concentration Pathway (6.0 and 8.5) scenarios (2040-2050 and 2090-2100) have been considered for this work. Current and future suitability patterns, species distribution, richness, and turnover were calculated using the minimum volume ellipsoids as algorithm. The results in this study highlight that beyond migration to higher latitudes, upwelling regions could protect marine fishes, although the mechanism differed between the innate characteristics of upwellings. Most modeled species (primarily tropical fishes) found refuge in the tropical upwelling in Northern Yucatan. However, the highest warming scenario overwhelmed this region. In contrast, the Baja California region lies within the Eastern Boundary Upwelling Systems. While the area experiences an increase in suitability, the northern regions have a higher upwelling intensity acting as environmental barriers for many tropical species. Conversely, in the southern regions where upwelling is weaker, species tend to congregate and persist even during elevated warming, according to the turnover analysis. These findings suggest that tropicalization in higher latitudes may not be as straightforward as previously assumed. Nevertheless, climate change affects numerous ecosystem features, such as trophic relationships, phenology, and other environmental variables not considered here. In addition, uncertainty still exists about the assumption of increasing intensity of upwelling systems.
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Affiliation(s)
- Luis Enrique Angeles-Gonzalez
- Laboratorio de Ecofisiología de Organismos Acuáticos, Departamento de Biotecnología Marina Centro de Investigación Científica y de Educación Superior de Ensenada, (CICESE), Carretera Ensenada-Tijuana #3918, 22860, Ensenada, Baja California, Mexico; Cousteau Group, San Juan Lurigancho, Lima, Peru, 15096
| | - Josymar Torrejón-Magallanes
- Cousteau Group, San Juan Lurigancho, Lima, Peru, 15096; Instituto del Mar del Perú, Esquina Gamarra y General Valle s/n Chucuito, Callao, Peru
| | - Angel Escamilla-Aké
- Unidad Multidisciplinaria de Docencia e Investigación, Facultad de Ciencias, Universidad Nacional Autónoma de México. 9735 Sisal, Yucatán, Mexico; Centro para el Desarrollo Educativo, Científico, Tecnológico y Ambiental (CEDECTYA A.C.), Calle 21, 97500, Dzidzantún, Yucatán, Mexico
| | - Luis Osorio-Olvera
- Departamento de Ecología de la Biodiversidad, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04500, Coyoacán, Ciudad de México, Mexico
| | - Otilio Avendaño
- Unidad Multidisciplinaria de Docencia e Investigación, Facultad de Ciencias, Universidad Nacional Autónoma de México. 9735 Sisal, Yucatán, Mexico
| | - Fernando Díaz
- Laboratorio de Ecofisiología de Organismos Acuáticos, Departamento de Biotecnología Marina Centro de Investigación Científica y de Educación Superior de Ensenada, (CICESE), Carretera Ensenada-Tijuana #3918, 22860, Ensenada, Baja California, Mexico
| | - Carlos Rosas
- Unidad Multidisciplinaria de Docencia e Investigación, Facultad de Ciencias, Universidad Nacional Autónoma de México. 9735 Sisal, Yucatán, Mexico.
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McWhorter JK, Halloran PR, Roff G, Mumby PJ. Climate change impacts on mesophotic regions of the Great Barrier Reef. Proc Natl Acad Sci U S A 2024; 121:e2303336121. [PMID: 38588432 PMCID: PMC11032494 DOI: 10.1073/pnas.2303336121] [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: 02/27/2023] [Accepted: 02/28/2024] [Indexed: 04/10/2024] Open
Abstract
Climate change projections for coral reefs are founded exclusively on sea surface temperatures (SST). While SST projections are relevant for the shallowest reefs, neglecting ocean stratification overlooks the striking differences in temperature experienced by deeper reefs for all or part of the year. Density stratification creates a buoyancy barrier partitioning the upper and lower parts of the water column. Here, we mechanistically downscale climate models and quantify patterns of thermal stratification above mesophotic corals (depth 30 to 50 m) of the Great Barrier Reef (GBR). Stratification insulates many offshore regions of the GBR from heatwaves at the surface. However, this protection is lost once global average temperatures exceed ~3 °C above preindustrial, after which mesophotic temperatures surpass a recognized threshold of 30 °C for coral mortality. Bottom temperatures on the GBR (30 to 50 m) from 2050 to 2060 are estimated to increase by ~0.5 to 1 °C under lower climate emissions (SSP1-1.9) and ~1.2 to 1.7 °C under higher climate emissions (SSP5-8.5). In short, mesophotic coral reefs are also threatened by climate change and research might prioritize the sensitivity of such corals to stress.
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Affiliation(s)
- Jennifer K. McWhorter
- Faculty of Environment, Science and Economy, University of Exeter, ExeterEX4 4QJ, United Kingdom
- Marine Spatial Ecology Lab, School of the Environment The University of Queensland, St Lucia, QLD4072, Australia
- National Oceanic and Atmospheric Administration, Atlantic Oceanographic and Meteorological Laboratory, Ocean Chemistry and Ecosystem Divisions, Miami, FL33149
| | - Paul R. Halloran
- Faculty of Environment, Science and Economy, University of Exeter, ExeterEX4 4QJ, United Kingdom
| | - George Roff
- Marine Spatial Ecology Lab, School of the Environment The University of Queensland, St Lucia, QLD4072, Australia
- Commonwealth Scientific and Industrial Research Organisation, Oceans & Atmosphere, St Lucia, QLD 4000, Australia
| | - Peter J. Mumby
- Marine Spatial Ecology Lab, School of the Environment The University of Queensland, St Lucia, QLD4072, Australia
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Mason RAB, Bozec YM, Mumby PJ. Demographic resilience may sustain significant coral populations in a 2°C-warmer world. GLOBAL CHANGE BIOLOGY 2023; 29:4152-4160. [PMID: 37097011 DOI: 10.1111/gcb.16741] [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: 01/02/2023] [Revised: 04/05/2023] [Accepted: 04/06/2023] [Indexed: 05/03/2023]
Abstract
Projections of coral reefs under climate change have important policy implications, but most analyses have focused on the intensification of climate-related physical stress rather than explicitly modelling how coral populations respond to stressors. Here, we analyse the future of the Great Barrier Reef (GBR) under multiple, spatially realistic drivers which allows less impacted sites to facilitate recovery. Under a Representative Concentration Pathway (RCP) 2.6 CMIP5 climate ensemble, where warming is capped at ~2°C, GBR mean coral cover declined mid-century but approached present-day levels towards 2100. This is considerably more optimistic than most analyses. However, under RCP4.5, mean coral cover declined by >80% by late-century, and reached near zero under RCP ≥6.0. While these models do not allow for adaptation, they significantly extend past studies by revealing demographic resilience of coral populations to low levels of additional warming, though more pessimistic outcomes might be expected under CMIP6. Substantive coral populations under RCP2.6 would facilitate long-term genetic adaptation, adding value to ambitious greenhouse emissions mitigation.
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Affiliation(s)
- Robert A B Mason
- School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia
| | - Yves-Marie Bozec
- School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia
| | - Peter J Mumby
- School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia
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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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Mason RAB, Bozec YM, Mumby PJ. Setting sustainable limits on anchoring to improve the resilience of coral reefs. MARINE POLLUTION BULLETIN 2023; 189:114721. [PMID: 36907169 DOI: 10.1016/j.marpolbul.2023.114721] [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: 11/10/2022] [Revised: 02/05/2023] [Accepted: 02/07/2023] [Indexed: 06/18/2023]
Abstract
Boat anchoring is common at coral reefs that have high economic or social value, but anchoring has received relatively little attention in reef resilience studies. We developed an individual-based model of coral populations and simulated the effects of anchor damage over time. The model allowed us to estimate the carrying capacity of anchoring for four different coral assemblages and different starting levels of coral cover. The carrying capacity of small to medium-sized recreational vessels across these four assemblages was between 0 and 3.1 anchor strikes ha-1 day-1. In a case study of two Great Barrier Reef archipelagos, we modelled the benefits of anchoring mitigation under bleaching regimes expected for four climate scenarios. The partial mitigation of even a very mild anchoring incidence (1.17 strikes ha-1 day-1) resulted in median coral gains of 2.6-7.7 % absolute cover under RCP2.6, though benefits varied temporally and depended on the Atmosphere-Ocean General Circulation Model used.
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Affiliation(s)
- Robert A B Mason
- School of Biological Sciences, University of Queensland, St. Lucia, Queensland 4072, Australia.
| | - Yves-Marie Bozec
- School of Biological Sciences, University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Peter J Mumby
- School of Biological Sciences, University of Queensland, St. Lucia, Queensland 4072, Australia
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Abstract
Corals have long been known to generate local fluid flows using ciliary beating, but the importance of these ciliary flows is just being discovered. Two new papers shed light on how ciliary-flow physics plays a key role in shaping coral physiology.
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