Environmental impact on the mechanical properties of Porites spp. corals

Moynihan, Molly A., Amini, Shahrouz, Goodkin, Nathalie F., Tanzil, Jani T. I., Chua, J. Q. Isaiah, Fabbro, Gareth N. ORCID: https://orcid.org/0000-0001-5334-2010, Fan, Tung-Yung, Schmidt, Daniela N. and Miserez, Ali (2021) Environmental impact on the mechanical properties of Porites spp. corals. Coral Reefs, 40 (3). pp. 701-717. ISSN 0722-4028

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Despite the economic and ecological importance of corals’ skeletal structure, as well as their predicted vulnerability to future climate change, few studies have examined the skeletal mechanical properties at the nanoscale. As climate change is predicted to alter coral growth and physiology, as well as increase mechanical stress events (e.g., bioerosion, storm frequency), it is crucial to understand how skeletal mechanical properties change with environmental conditions. Moreover, while material properties are intimately linked to the chemical composition of the skeleton, no previous study has examined mechanical properties alongside carbonate geochemical composition. Using Porites coral cores from a wide range of reef environments (Thailand, Singapore, Taiwan), we correlated coral’s micro-mechanical properties with chemical composition. In contrast to previous mechanical measurements of reef-building corals, we document unprecedented variability in the hardness, stiffness, and micro-cracking stress of Porites corals across reef environments, which may significantly decrease the structural integrity of reef substrate. Corals from environments with low salinity and high sedimentation had higher organic content and fractured at lower loads, suggesting that skeletal organic content caused enhanced embrittlement. Within individual coral cores, we observed seasonal variability in skeletal stiffness, and a relationship between high sea surface temperature, increased stiffness, and high-density. Regionally, lower Sr/Ca and higher Mg/Ca coincided with decreased stiffness and hardness, which is likely driven by increased amorphous calcium carbonate and skeletal organic content. If the coral is significantly embrittled, as measured here in samples from Singapore, faster erosion is expected. A decrease in skeletal stiffness will decrease the quality of reef substrate, enhance the rate of bioerosion by predators and borers, and increase colony dislodgement, resulting in widespread loss of structural complexity.

Item Type: Article
Additional Information: Funding Information: We thank the Earth Observatory of Singapore, Asian School of the Environment, Nanyang Technological University, National Research Foundation Singapore (NRF-RF2012-03), Singapore Ministry of Education, Research Centers of Excellence initiative, and the Marine Science R&D Programme (MSRDP-P03 and MSRDP-P29) for financial and logistical support. Thanks to the Phuket Marine Biological Centre and the National Research Council of Thailand (Proj. ID 2009/043), and the Singapore National Parks (NP/RP16-156-2a). Many thanks to Jeff Oalmann for assistance with the Iolite software, and to Kyle M. Morgan and Riovie Ramos for thoughtful discussions. This work comprises Earth Observatory of Singapore contribution 347.
Uncontrolled Keywords: coral geochemistry,mechanical response,micro-cracking,organic content,porites,aquatic science,sdg 13 - climate action ,/dk/atira/pure/subjectarea/asjc/1100/1104
Faculty \ School: Faculty of Science > School of Environmental Sciences
UEA Research Groups: Faculty of Science > Research Groups > Geosciences
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Depositing User: LivePure Connector
Date Deposited: 19 Oct 2022 12:30
Last Modified: 23 Jul 2024 01:58
URI: https://ueaeprints.uea.ac.uk/id/eprint/89208
DOI: 10.1007/s00338-021-02064-3


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