Projected shifts in coral size structure in the Anthropocene

Pisapia, Chiara, Edmunds, Peter J., Moeller, Holly V., Riegel, Bernhard, McWilliam, Mike, Wells, Christopher D., and Pratchett, Morgan S. (2020) Projected shifts in coral size structure in the Anthropocene. Advances in Marine Biology, 87 (1). pp. 31-60.

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Abstract

Changes in the size structure of coral populations have major consequences for population dynamics and community function, yet many coral reef monitoring projects do not record this critical feature. Consequently, our understanding of current and future trajectories in coral size structure, and the demographic processes underlying these changes, is still emerging. Here, we provide a conceptual summary of the benefits to be gained from more comprehensive attention to the size of coral colonies in reef monitoring projects, and we support our argument through the use of case-history examples and a simplified ecological model. We neither seek to review the available empirical data, or to rigorously explore causes and implications of changes in coral size, we seek to reveal the advantages to modifying ongoing programs to embrace the information inherent in changing coral colony size. Within this framework, we evaluate and forecast the mechanics and implications of changes in the population structure of corals that are transitioning from high to low abundance, and from large to small colonies, sometimes without striking effects on planar coral cover. Using two coral reef locations that have been sampled for coral size, we use demographic data to underscore the limitations of coral cover in understanding the causes and consequences of long-term declining coral size, and abundance. A stage-structured matrix model is used to evaluate the demographic causes of declining coral colony size and abundance, particularly with respect to the risks of extinction. The model revealed differential effects of mortality, growth and fecundity on coral size distributions. It also suggested that colony rarity and declining colony size in association with partial tissue mortality and chronic declines in fecundity, can lead to a demographic bottleneck with the potential to prolong the existence of coral populations when they are characterized by mostly very small colonies. Such bottlenecks could have ecological importance if they can delay extinction and provide time for human intervention to alleviate the environmental degradation driving reductions in coral abundance.

Item ID: 67394
Item Type: Article (Research - C1)
ISBN: 978-0-12-821529-6
ISSN: 2162-5875
Keywords: Coral abundance, Coral reef crisis, Fecundity, Growth, Mortality, Small corals, Stage-structured matrix model
Copyright Information: © 2020 Elsevier Ltd
Funders: ARC Centre of Excellence for Coral Reef Studies
Date Deposited: 31 May 2021 23:01
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 50%
41 ENVIRONMENTAL SCIENCES > 4101 Climate change impacts and adaptation > 410102 Ecological impacts of climate change and ecological adaptation @ 50%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 20%
18 ENVIRONMENTAL MANAGEMENT > 1802 Coastal and estuarine systems and management > 180201 Assessment and management of coastal and estuarine ecosystems @ 80%
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