Exposure to elevated sea-surface temperatures below the bleaching threshold impairs coral recovery and regeneration following injury

Bonesso, Joshua Louis, Leggat, William, and Ainsworth, Tracy Danielle (2017) Exposure to elevated sea-surface temperatures below the bleaching threshold impairs coral recovery and regeneration following injury. PeerJ, 5. e3719.

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Abstract

Elevated sea surface temperatures (SSTs) are linked to an increase in the frequency and severity of bleaching events due to temperatures exceeding corals' upper thermal limits. The temperatures at which a breakdown of the coral-Syrnbiodinium endosymbiosis (coral bleaching) occurs are referred to as the upper thermal limits for the coral species. This breakdown of the endosymbiosis results in a reduction of corals' nutritional uptake, growth, and tissue integrity. Periods of elevated sea surface temperature, thermal stress and coral bleaching are also linked to increased disease susceptibility and an increased frequency of storms which cause injury and physical damage to corals. Herein we aimed to determine the capacity of corals to regenerate and recover from injuries (removal of apical tips) sustained during periods of elevated sea surface temperatures which result in coral stress responses, but which do not result in coral bleaching (i.e., sub-bleaching thermal stress events). In this study, exposure of the species Acropora aspera to an elevated SST of 32 degrees C (2 degrees C below the bleaching threshold, 34 degrees C) was found to result in reduced fluorescence of green fluorescent protein (GFP), reduced skeletal calcification and a lack of branch regrowth at the site of injury, compared to corals maintained under ambient SST conditions (26 degrees C). Corals maintained under normal, ambient, sea surface temperatures expressed high GFP fluorescence at the injury site, unclerwent a rapid regeneration of the coral branch apical tip within 12 days of sustaining injury, and showed extensive regrowth of the coral skeleton. Taken together, our results have demonstrated that periods of sustained increased sea surface temperatures, below the corals' bleaching threshold but above long-term summertime averages, impair coral recover/from damage, regardless of the onset or occurrence of coral bleaching.

Item ID: 51393
Item Type: Article (Research - C1)
ISSN: 2167-8359
Keywords: coral reefs, GFP, heat shock proteins (HSP), injury, recovery, Scanning Electron Microscopy (SEM), temperature stress
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Distributed under Creative Commons CC-BY 4.0

Funders: Australian Research Council (ARC), Australian Research Council (ARC) Centre of Excellence for Coral Reef Studies (CE)
Projects and Grants: ARC Discovery Program grant number DP130101421, ARC Super Science Program grant number FS110200046, ARC-CE grant number CE0561435
Date Deposited: 01 Nov 2017 07:31
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050101 Ecological Impacts of Climate Change @ 100%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960301 Climate Change Adaptation Measures @ 100%
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