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ORIGINAL RESEARCH article

Front. Mar. Sci.
Sec. Coral Reef Research
Volume 11 - 2024 | doi: 10.3389/fmars.2024.1333806

Shading responses are species-specific in thermally stressed corals

Provisionally accepted
Sophia L. Ellis Sophia L. Ellis 1*Peter Butcherine Peter Butcherine 1Alejandro Tagliafico Alejandro Tagliafico 1Conor A. Hendrickson Conor A. Hendrickson 1Brendan P. Kelaher Brendan P. Kelaher 1Kai G. Schulz Kai G. Schulz 2Daniel P. Harrison Daniel P. Harrison 1,3
  • 1 National Marine Science Centre, School of Environment, Science and Engineering, Southern Cross University, Coffs Harbour, Australia
  • 2 Centre for Coastal Biogeochemistry, School of Environment, Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia
  • 3 School of Geosciences, Faculty of Science, The University of Sydney, Sydney, New South Wales, Australia

The final, formatted version of the article will be published soon.

    Light is critical to coral growth through endosymbiont photosynthesis but can also act with elevated temperatures to cause coral bleaching. When more light is absorbed than can be used for photosynthesis, elevated irradiance can damage symbiont photosynthetic machinery.Hence, solar-radiation management through shading has been suggested to alleviate coral bleaching during marine heatwaves. Acropora divaricata and Acropora kenti were tested at two temperatures with 30% shading and an unshaded control to determine the relative impacts of light and temperature on coral bleaching severity. The coral bleaching response was assessed by photochemical (pulse amplitude modulated fluorometry), physiological (symbiont density, chlorophyll a concentration, catalase activity, and lipid peroxidation), and physical (mean intensity of grey or 'percentage whiteness') markers. Shading significantly reduced the bleaching response in A. divaricata, whilst for some parameters A. kenti responded negatively to shade. In A. divaricata, shading prevented photochemical collapse up to the experiment's maximum 4.4 degree-heating weeks (DHW). Biomarkers of coral bleaching stress responded to shade and water temperature at 4.4 DHW; catalase activity was greatest in the shaded and ambient temperature treatment. Shading did not reduce the effects of bleaching in A. kenti; the mean intensity of grey and light saturation coefficient was greatest in the shaded treatment. Shading did, however, reduce lipid peroxidation at 3 DHW.Our results suggest shading during thermal stress may only protect some coral species, highlighting the need to consider species-specific responses when evaluating the potential efficacy of coral bleaching interventions.

    Keywords: Scleractinia, irradiance, solar-radiation management, Environmental stressor, Climate Change, Oxidative Stress, Photochemistry, physiological

    Received: 06 Nov 2023; Accepted: 31 Jul 2024.

    Copyright: © 2024 Ellis, Butcherine, Tagliafico, Hendrickson, Kelaher, Schulz and Harrison. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Sophia L. Ellis, National Marine Science Centre, School of Environment, Science and Engineering, Southern Cross University, Coffs Harbour, Australia

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