Rapid coral decay is associated with marine heatwave mortality events on reefs

Leggat, William P., Camp, Emma F., Suggett, David J., Heron, Scott F., Fordyce, Alexander J., Gardner, Stephanie, Deakin, Lachlan, Turner, Michael, Beeching, Levi J., Kuzhiumparambil, Unnikrishnan, Eakin, C. Mark, and Ainsworth, Tracy D. (2019) Rapid coral decay is associated with marine heatwave mortality events on reefs. Current Biology, 29 (16). pp. 2723-2730.

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Abstract

[Excerpt] Severe marine heatwaves have recently become a common feature of global ocean conditions due to a rapidly changing climate [1, 2]. These increasingly severe thermal conditions are causing an unprecedented increase in the frequency and severity of mortality events in marine ecosystems, including on coral reefs [3]. The degradation of coral reefs will result in the collapse of ecosystem services that sustain over half a billion people globally [4, 5]. Here, we show that marine heatwave events on coral reefs are biologically distinct to how coral bleaching has been understood to date, in that heatwave conditions result in an immediate heat-induced mortality of the coral colony, rapid coral skeletal dissolution, and the loss of the three-dimensional reef structure. During heatwave-induced mortality, the coral skeletons exposed by tissue loss are, within days, encased by a complex biofilm of phototrophic microbes, whose metabolic activity accelerates calcium carbonate dissolution to rates exceeding accretion by healthy corals and far greater than has been documented on reefs under normal seawater conditions. This dissolution reduces the skeletal density and hardness and increases porosity. These results demonstrate that severe-heatwave-induced mortality events should be considered as a distinct biological phenomenon from bleaching events on coral reefs. We also suggest that such heatwave mortality events, and rapid reef decay, will become more frequent as the intensity of marine heatwaves increases and provides further compelling evidence for the need to mitigate climate change and instigate actions to reduce marine heatwaves.

Item ID: 60405
Item Type: Article (Research - C1)
ISSN: 1879-0445
Copyright Information: © 2019 Elsevier Ltd.
Funders: Australian Research Council Centre of Excellence for Coral Reef Studies (ARC CECRS), Great Barrier Reef Foundation (GBRF), Australian Research Council Discovery Project (ARC-DP), NOAA NESDIS, NOAA Coral Reef Conservation Program
Projects and Grants: ARC CECRS CE0561435, GBRF Coral Health Grant, ARC-DP grant DP160100271
Date Deposited: 11 Sep 2019 07:32
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050204 Environmental Impact Assessment @ 100%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960303 Climate Change Models @ 100%
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