Rising cover amid population density decline: the unstable demography of a reef-building coral

Monitoring habitat-forming species, such as scleractinian corals, is crucial for managing ecosystems and biodiversity. Yet for assessing population health, challenges remain in reconciling conventional areal coverage surveys with individual-based demographic techniques. Here, we explore both monitor...

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Main Authors: Liam Lachs, Alex Ward, Elizabeth A. Beauchamp, Alasdair J. Edwards, Renata Ferrari, Will F. Figueira, Yimnang Golbuu, Adriana Humanes, Helios M. Martinez, Daniel R. Pygas, Brigitte Sommer, Eveline van der Steeg, John C. Bythell, James R. Guest
Format: Article
Language:English
Published: The Royal Society 2025-07-01
Series:Royal Society Open Science
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Online Access:https://royalsocietypublishing.org/doi/10.1098/rsos.250271
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author Liam Lachs
Alex Ward
Elizabeth A. Beauchamp
Alasdair J. Edwards
Renata Ferrari
Will F. Figueira
Yimnang Golbuu
Adriana Humanes
Helios M. Martinez
Daniel R. Pygas
Brigitte Sommer
Eveline van der Steeg
John C. Bythell
James R. Guest
author_facet Liam Lachs
Alex Ward
Elizabeth A. Beauchamp
Alasdair J. Edwards
Renata Ferrari
Will F. Figueira
Yimnang Golbuu
Adriana Humanes
Helios M. Martinez
Daniel R. Pygas
Brigitte Sommer
Eveline van der Steeg
John C. Bythell
James R. Guest
author_sort Liam Lachs
collection DOAJ
description Monitoring habitat-forming species, such as scleractinian corals, is crucial for managing ecosystems and biodiversity. Yet for assessing population health, challenges remain in reconciling conventional areal coverage surveys with individual-based demographic techniques. Here, we explore both monitoring approaches to characterize the population dynamics of the reef-building coral, Acropora cf. digitifera, on a West Pacific outer reef using photogrammetry reef mapping data spanning 5 years. Tracking 906 coral colonies showed that those exceeding approximately 10 cm diameter exhibit the fastest planar growth but also suffer excess mortality, possibly owing to increased structural vulnerability to dislodgement by wave energy or to other factors, such as disease or predation, that may be exacerbated by senescence. Area-controlled orthomosaic subsampling paired to integral projection modelling revealed a consistent decline in population density, as recruitment was insufficient to balance losses of larger colonies. Yet, total areal coverage and median colony size increased over the study, suggesting this disequilibrium population is on a recovery trajectory from past disturbance and heavily reliant on sporadic recruitment pulses not detected in our study. We find that conventional areal monitoring and demographic approaches can yield contrasting conclusions about population dynamics. Reconciling these differences for disequilibrium populations requires long-term demographic data over periods long enough to detect infrequent yet critical demographic events such as large post-disturbance recruitment events.
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spelling doaj-art-e47cd97e00ce421c95c1d7ae02c330472025-08-20T03:25:59ZengThe Royal SocietyRoyal Society Open Science2054-57032025-07-0112710.1098/rsos.250271Rising cover amid population density decline: the unstable demography of a reef-building coralLiam Lachs0Alex Ward1Elizabeth A. Beauchamp2Alasdair J. Edwards3Renata Ferrari4Will F. Figueira5Yimnang Golbuu6Adriana Humanes7Helios M. Martinez8Daniel R. Pygas9Brigitte Sommer10Eveline van der Steeg11John C. Bythell12James R. Guest13School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UKSchool of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UKSchool of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UKSchool of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UKAustralian Institute of Marine Science, Townsville City, AustraliaSchool of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, AustraliaPalau International Coral Reef Centre, Koror, PalauSchool of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UKSchool of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UKSchool of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, AustraliaSchool of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, AustraliaSchool of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UKSchool of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UKSchool of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UKMonitoring habitat-forming species, such as scleractinian corals, is crucial for managing ecosystems and biodiversity. Yet for assessing population health, challenges remain in reconciling conventional areal coverage surveys with individual-based demographic techniques. Here, we explore both monitoring approaches to characterize the population dynamics of the reef-building coral, Acropora cf. digitifera, on a West Pacific outer reef using photogrammetry reef mapping data spanning 5 years. Tracking 906 coral colonies showed that those exceeding approximately 10 cm diameter exhibit the fastest planar growth but also suffer excess mortality, possibly owing to increased structural vulnerability to dislodgement by wave energy or to other factors, such as disease or predation, that may be exacerbated by senescence. Area-controlled orthomosaic subsampling paired to integral projection modelling revealed a consistent decline in population density, as recruitment was insufficient to balance losses of larger colonies. Yet, total areal coverage and median colony size increased over the study, suggesting this disequilibrium population is on a recovery trajectory from past disturbance and heavily reliant on sporadic recruitment pulses not detected in our study. We find that conventional areal monitoring and demographic approaches can yield contrasting conclusions about population dynamics. Reconciling these differences for disequilibrium populations requires long-term demographic data over periods long enough to detect infrequent yet critical demographic events such as large post-disturbance recruitment events.https://royalsocietypublishing.org/doi/10.1098/rsos.250271recoverycoral reefsintermediate disturbance hypothesisintegral projection modellingphotogrammetrydemography
spellingShingle Liam Lachs
Alex Ward
Elizabeth A. Beauchamp
Alasdair J. Edwards
Renata Ferrari
Will F. Figueira
Yimnang Golbuu
Adriana Humanes
Helios M. Martinez
Daniel R. Pygas
Brigitte Sommer
Eveline van der Steeg
John C. Bythell
James R. Guest
Rising cover amid population density decline: the unstable demography of a reef-building coral
Royal Society Open Science
recovery
coral reefs
intermediate disturbance hypothesis
integral projection modelling
photogrammetry
demography
title Rising cover amid population density decline: the unstable demography of a reef-building coral
title_full Rising cover amid population density decline: the unstable demography of a reef-building coral
title_fullStr Rising cover amid population density decline: the unstable demography of a reef-building coral
title_full_unstemmed Rising cover amid population density decline: the unstable demography of a reef-building coral
title_short Rising cover amid population density decline: the unstable demography of a reef-building coral
title_sort rising cover amid population density decline the unstable demography of a reef building coral
topic recovery
coral reefs
intermediate disturbance hypothesis
integral projection modelling
photogrammetry
demography
url https://royalsocietypublishing.org/doi/10.1098/rsos.250271
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