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High-latitude marginal reefs support fewer but bigger corals than their tropical counterparts
  • +9
  • Fiona Chong,
  • Brigitte Sommer,
  • Georgia Stant,
  • Nina Verano,
  • James Cant,
  • Liam Lachs,
  • Magnus Johnson,
  • Daniel Parsons,
  • John M. Pandolfi,
  • Roberto Salguero-Gómez,
  • Matthew Spencer,
  • Maria Beger
Fiona Chong
University of Hull

Corresponding Author:[email protected]

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Brigitte Sommer
The University of Sydney School of Life and Environmental Sciences
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Georgia Stant
University of Leeds
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Nina Verano
University of Leeds
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James Cant
University of St Andrews
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Liam Lachs
Newcastle University
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Magnus Johnson
University of Hull
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Daniel Parsons
University of Hull
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John M. Pandolfi
The University of Queensland
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Roberto Salguero-Gómez
University of Oxford
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Matthew Spencer
University of Liverpool
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Maria Beger
University of Leeds
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Abstract

Anthropogenic impacts are typically detrimental to tropical coral reefs, but the effect of increasing environmental stress and variability on the size structure of coral communities remains poorly understood. This limits our ability to effectively conserve coral reef ecosystems because size specific dynamics are rarely incorporated. Our aim is to quantify variation in the size structure of coral populations across 20 sites along a tropical-to-subtropical environmental gradient on the east coast of Australia (~23°S to 30°S), to determine how size structure changes with a gradient of sea surface temperature, turbidity, productivity and light levels. We use two approaches: 1) linear regression with summary statistics (such as median size) as response variables, a method frequently favoured by ecologists; and 2) compositional functional regression, a novel method using entire size-frequency distributions as response variables. We then predict coral population size structure with increasing environmental stress and variability. Together, we find fewer but larger coral colonies in marginal reefs than in tropical reefs, where environmental conditions are more variable and stressful for tropical corals. Our model predicts that coral populations may become gradually dominated by larger colonies (> 148 cm2) with increasing environmental stress. Fewer but bigger corals suggest low survival of smaller corals, slow growth, and / or poor recruitment. This finding is concerning for the future of coral reefs as it implies populations may have low recovery potential from disturbances. We highlight the importance of continuously monitoring changes to population structure over biogeographic scales.
05 Mar 2023Submitted to Ecography
06 Mar 2023Submission Checks Completed
06 Mar 2023Assigned to Editor
06 Mar 2023Review(s) Completed, Editorial Evaluation Pending
03 Apr 2023Reviewer(s) Assigned
24 May 2023Editorial Decision: Revise Major
30 Jun 20231st Revision Received
03 Jul 2023Submission Checks Completed
03 Jul 2023Assigned to Editor
03 Jul 2023Review(s) Completed, Editorial Evaluation Pending
03 Jul 2023Reviewer(s) Assigned
26 Jul 2023Editorial Decision: Revise Minor
06 Aug 20232nd Revision Received
07 Aug 2023Submission Checks Completed
07 Aug 2023Assigned to Editor
07 Aug 2023Review(s) Completed, Editorial Evaluation Pending
09 Aug 2023Editorial Decision: Accept