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Sommer B, Hodge JM, Lachs L, Cant J, Pandolfi JM, Beger M. Decadal demographic shifts and size-dependent disturbance responses of corals in a subtropical warming hotspot. Sci Rep 2024; 14:6327. [PMID: 38491152 PMCID: PMC10943097 DOI: 10.1038/s41598-024-56890-w] [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: 12/04/2023] [Accepted: 03/12/2024] [Indexed: 03/18/2024] Open
Abstract
Long-term demographic studies at biogeographic transition zones can elucidate how body size mediates disturbance responses. Focusing on subtropical reefs in eastern Australia, we examine trends in the size-structure of corals with contrasting life-histories and zoogeographies surrounding the 2016 coral bleaching event (2010-2019) to determine their resilience and recovery capacity. We document demographic shifts, with disproportionate declines in the number of small corals and long-term persistence of larger corals. The incidence of bleaching (Pocillopora, Turbinaria) and partial mortality (Acropora, Pocillopora) increased with coral size, and bleached corals had greater risk of partial mortality. While endemic Pocillopora experienced marked declines, decadal stability of Turbinaria despite bleaching, coupled with abundance increase and bleaching resistance in Acropora indicate remarkable resilience of these taxa in the subtropics. Declines in the number of small corals and variable associations with environmental drivers indicate bottlenecks to recovery mediated by inhibitory effects of thermal extremes for Pocillopora (heat stress) and Acropora (heat and cold stress), and stimulatory effects of chlorophyll-a for Turbinaria. Although our study reveals signs of resilience, it foreshadows the vulnerability of subtropical corals to changing disturbance regimes that include marine heatwaves. Disparity in population dynamics suggest that subtropical reefs are ecologically distinct from tropical coral reefs.
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Affiliation(s)
- Brigitte Sommer
- School of Life and Environmental Science, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Jessica M Hodge
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Maldives Underwater Initiative, Six Senses Laamu, Olhuveli Island, Laamu Atoll, Republic of Maldives
| | - Liam Lachs
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - James Cant
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Centre for Biological Diversity, University of St Andrews, St Andrews, KY16 9TH, Scotland, UK
| | - John M Pandolfi
- School of the Environment, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Maria Beger
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Centre for Biodiversity and Conservation Science, School of Biological Sciences, University of Queensland, Brisbane, QLD, 4072, Australia
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Randrianarivo M, Botosoamananto RL, Guilhaumon F, Penin L, Todinanahary G, Adjeroud M. Effects of Madagascar marine reserves on juvenile and adult coral abundance, and the implication for population regulation. MARINE ENVIRONMENTAL RESEARCH 2023; 190:106080. [PMID: 37422994 DOI: 10.1016/j.marenvres.2023.106080] [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: 09/27/2022] [Revised: 06/30/2023] [Accepted: 07/05/2023] [Indexed: 07/11/2023]
Abstract
Recruitment is a critical component in the dynamics of coral assemblages, and a key question is to determine the degree to which spatial heterogeneity of adults is influenced by pre-vs. post-settlement processes. We analyzed the density of juvenile and adult corals among 18 stations located at three regions around Madagascar, and examined the effects of Marine Protected Areas (MPAs). Our survey did not detect a positive effect of MPAs on juveniles, except for Porites at the study scale. The MPA effect was more pronounced for adults, notably for Acropora, Montipora, Seriatopora, and Porites at the regional scale. For most dominant genera, densities of juveniles and adults were positively correlated at the study scale, and at least at one of the three regions. These outcomes suggest recruitment-limitation relationships for several coral taxa, although differences in post-settlement events may be sufficiently strong to distort the pattern established at settlement for other populations. The modest benefits of MPAs on the density of juvenile corals demonstrated here argue in favor of strengthening conservation measures more specifically focused to protect recruitment processes.
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Affiliation(s)
- Mahery Randrianarivo
- Institut Halieutique et des Sciences Marines, Université de Toliara, Toliara, Madagascar; ENTROPIE, Université de La Réunion, IRD, CNRS, IFREMER, Université de la Nouvelle-Calédonie, La Réunion, France
| | - Radonirina Lebely Botosoamananto
- Institut Halieutique et des Sciences Marines, Université de Toliara, Toliara, Madagascar; ENTROPIE, Université de La Réunion, IRD, CNRS, IFREMER, Université de la Nouvelle-Calédonie, La Réunion, France
| | - François Guilhaumon
- ENTROPIE, Université de La Réunion, IRD, CNRS, IFREMER, Université de la Nouvelle-Calédonie, La Réunion, France
| | - Lucie Penin
- ENTROPIE, Université de La Réunion, IRD, CNRS, IFREMER, Université de la Nouvelle-Calédonie, La Réunion, France; Laboratoire d'Excellence "CORAIL", Paris, France
| | - Gildas Todinanahary
- Institut Halieutique et des Sciences Marines, Université de Toliara, Toliara, Madagascar
| | - Mehdi Adjeroud
- ENTROPIE, IRD, Université de la Réunion, CNRS, IFREMER, Université de la Nouvelle-Calédonie, Perpignan, France; Laboratoire d'Excellence "CORAIL", Paris, France; PSL Université Paris, UAR 3278, CRIOBE EPHE-UPVD-CNRS, Perpignan, France.
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McWilliam M, Dornelas M, Álvarez-Noriega M, Baird AH, Connolly SR, Madin JS. Net effects of life-history traits explain persistent differences in abundance among similar species. Ecology 2023; 104:e3863. [PMID: 36056537 DOI: 10.1002/ecy.3863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 06/22/2022] [Accepted: 07/18/2022] [Indexed: 02/01/2023]
Abstract
Life-history traits are promising tools to predict species commonness and rarity because they influence a population's fitness in a given environment. Yet, species with similar traits can have vastly different abundances, challenging the prospect of robust trait-based predictions. Using long-term demographic monitoring, we show that coral populations with similar morphological and life-history traits show persistent (decade-long) differences in abundance. Morphological groups predicted species positions along two, well known life-history axes (the fast-slow continuum and size-specific fecundity). However, integral projection models revealed that density-independent population growth (λ) was more variable within morphological groups, and was consistently higher in dominant species relative to rare species. Within-group λ differences projected large abundance differences among similar species in short timeframes, and were generated by small but compounding variation in growth, survival, and reproduction. Our study shows that easily measured morphological traits predict demographic strategies, yet small life-history differences can accumulate into large differences in λ and abundance among similar species. Quantifying the net effects of multiple traits on population dynamics is therefore essential to anticipate species commonness and rarity.
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Affiliation(s)
- Mike McWilliam
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, USA
| | - Maria Dornelas
- Centre for Biological Diversity, Scottish Oceans Institute, University of St Andrews, St Andrews, UK
| | - Mariana Álvarez-Noriega
- Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Andrew H Baird
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
| | | | - Joshua S Madin
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, USA
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Shlesinger T, van Woesik R. Different population trajectories of two reef-building corals with similar life-history traits. J Anim Ecol 2021; 90:1379-1389. [PMID: 33666226 PMCID: PMC8252767 DOI: 10.1111/1365-2656.13463] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/26/2021] [Indexed: 01/01/2023]
Abstract
Increases in the frequency and intensity of acute and chronic disturbances are causing declines of coral reefs world‐wide. Although quantifying the responses of corals to acute disturbances is well documented, detecting subtle responses of coral populations to chronic disturbances is less common, but can also result in altered population and community structures. We investigated the population dynamics of two key reef‐building Merulinid coral species, Dipsastraea favus and Platygyra lamellina, with similar life‐history traits, in the Gulf of Eilat and Aqaba, Red Sea from 2015 to 2018, to assess potential differences in their population trajectories. Demographic processes, which included rates of survival, growth, reproduction and recruitment were used to parametrize integral projection models and estimate population growth rates and the likely population trajectories of both coral species. The survival and reproduction rates of both D. favus and P. lamellina were positively related to coral colony size, and elasticity analyses showed that large colonies most influenced population dynamics. Although both species have similar life‐history traits and growth morphologies and are generally regarded as ‘stress‐tolerant’, the populations showed contrasting trajectories—D. favus appears to be increasing whereas P. lamellina appears to be decreasing. As many corals have long‐life expectancies, the process of local and regional decline might be subtle and slow. Ecological assessments based on total living coral coverage, morphological groups or functional traits might overlook subtle, species‐specific trends. However, demographic approaches capable of detecting subtle species‐specific population changes can augment ecological studies and provide valuable early warning signs of decline before major coral loss becomes evident.
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Affiliation(s)
- Tom Shlesinger
- Institute for Global Ecology, Florida Institute of Technology, Melbourne, FL, USA
| | - Robert van Woesik
- Institute for Global Ecology, Florida Institute of Technology, Melbourne, FL, USA
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