Exposure to elevated sea-surface temperatures below the bleaching threshold impairs coral recovery and regeneration following injury
- Published
- Accepted
- Subject Areas
- Genetics, Marine Biology, Molecular Biology
- Keywords
- Coral Reefs, GFP, Heat Shock Proteins (HSP), Injury, Recovery, Scanning Electron Microscopy (SEM), Temperature Stress
- Copyright
- © 2017 Bonesso et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2017. Exposure to elevated sea-surface temperatures below the bleaching threshold impairs coral recovery and regeneration following injury. PeerJ Preprints 5:e2949v1 https://doi.org/10.7287/peerj.preprints.2949v1
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-Symbiodinium 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°C (2°C below the bleaching threshold, 34°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°C). Corals maintained under normal, ambient, sea surface temperatures expressed high GFP fluorescence at the injury site, underwent 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 recovery from damage, regardless of the onset or occurrence of coral bleaching .
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Raw dataset
Raw gene expression statistics for Catalase, HSP90 and HSP70
Supplementary microscopy images
Visible, GFP and SEM micrograph supplementary images