Differential size frequency distribution of hard coral colonies across physical reef health gradients in Northeast Peninsula Malaysia

Bernard, Gilles Gael Raphael; Kellam, Alexandra Lucie; Szereday, Sebastian

doi:10.1016/j.rsma.2023.102872

Cited by 2 publications

(1 citation statement)

References 68 publications

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“…Recent observations of speciation of endemic corals also indicate that evolutionary processes are at play in this region (Schmidt‐Roach et al 2013, Baird et al 2017). Where sample sizes are large enough, it will be meaningful to investigate taxa specific population size structure (Rich et al 2022, Bernard et al 2023) along this environmental gradient. Reefs with higher rugosity and thus complexity could support more smaller corals (Crabbe 2010), meaning reef topography could also be relevant.…”

Section: Discussionmentioning

confidence: 99%

High‐latitude marginal reefs support fewer but bigger corals than their tropical counterparts

Chong,

Sommer,

Stant

et al. 2023

Ecography

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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 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, where conditions are typically more variable and stressful, than in tropical reefs. 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 that current marginal populations, or future reefs in increasingly stressful environmental conditions may have low recovery potential. We highlight the importance of continuously monitoring changes to population structure over biogeographic scales.

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Section: Discussionmentioning

confidence: 99%

High‐latitude marginal reefs support fewer but bigger corals than their tropical counterparts

Chong,

Sommer,

Stant

et al. 2023

Ecography

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Back-to-back bleaching events in Peninsular Malaysia (2019–2020) selectively affect hard coral taxa across- and within-reef scales

Szereday,

Voolstra,

Amri

2024

Mar Biol

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The impacts of (repeat) bleaching events and the differential heat stress susceptibility of hard coral taxa are largely unknown in Malaysia, although it is part of the greater coral triangle. Here we determined bleaching trajectories of 46 hard coral taxa across- and within-reef scales based on data recorded during the first reported back-to-back coral bleaching occurrences in Malaysia between May 2019 and September 2020. Although the severity of coral bleaching in both years did not correspond to the rather small magnitude of heat stress observed, i.e., Degree Heating Weeks (DHW) of 1.05 °C-weeks and 0 °C-weeks in 2019 and 2020 respectively, we observed high levels of bleaching (55.21% and 26.63% of all surveyed colonies in 2019 and 2020, respectively). Notably, the bleaching response for both consecutive years was highly taxon-specific and significantly varied across- and within-reef scales. Mortality rates overall were low following the 2019 event, likely due to a rapid decrease in heat stress. Five of the 46 surveyed hard coral taxa exhibited more severe bleaching in 2020, despite a lower heat stress load. Interestingly, we observed low bleaching of ascribed susceptible taxa such as Acropora and Montipora, while we found taxa considered to be resilient, e.g. Heliopora and Porites, to exhibit severe bleaching, suggesting a reversal of bleaching hierarchies of taxa over time. Our findings provide a foundation for further coral bleaching studies in a region with few published records to enable more accurate regional assessments and to follow the trajectory of future coral bleaching events.

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Differential size frequency distribution of hard coral colonies across physical reef health gradients in Northeast Peninsula Malaysia

Cited by 2 publications

References 68 publications

High‐latitude marginal reefs support fewer but bigger corals than their tropical counterparts

High‐latitude marginal reefs support fewer but bigger corals than their tropical counterparts

Back-to-back bleaching events in Peninsular Malaysia (2019–2020) selectively affect hard coral taxa across- and within-reef scales

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