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Impacts of ocean acidification in naturally variable coral reef flat ecosystems


Shaw, EC and McNeil, BI and Tilbrook, B, Impacts of ocean acidification in naturally variable coral reef flat ecosystems, Journal of Geophysical Research-Oceans, 117, (C3) Article C03038. ISSN 0148-0227 (2012) [Refereed Article]


Copyright Statement

Copyright 2012 American Geophysical Union

DOI: doi:10.1029/2011JC007655


Ocean acidification leads to changes in marine carbonate chemistry that are predicted to cause a decline in future coral reef calcification. Several laboratory and mesocosm experiments have described calcification responses of species and communities to increasing CO2. The few in situ studies on natural coral reefs that have been carried out to date have shown a direct relationship between aragonite saturation state (Ωarag) and net community calcification (Gnet). However, these studies have been performed over a limited range of Ωarag values, where extrapolation outside the observational range is required to predict future changes in coral reef calcification. We measured extreme diurnal variability in carbonate chemistry within a reef flat in the southern Great Barrier Reef, Australia. Ωarag varied between 1.1 and 6.5, thus exceeding the magnitude of change expected this century in open ocean subtropical/tropical waters. The observed variability comes about through biological activity on the reef, where changes to the carbonate chemistry are enhanced at low tide when reef flat waters are isolated from open ocean water. We define a relationship between net community calcification and Ωarag, using our in situ measurements. We find net community calcification to be linearly related to Ωarag, while temperature and nutrients had no significant effect on Gnet. Using our relationship between Gnet and Ωarag, we predict that net community calcification will decline by 55% of its preindustrial value by the end of the century. It is not known at this stage whether exposure to large variability in carbonate chemistry will make reef flat organisms more or less vulnerable to the non-calcifying physiological effects of increasing ocean CO2 and future laboratory studies will need to incorporate this natural variability to address this question

Item Details

Item Type:Refereed Article
Keywords:ocean acidification, ecosystems, coral reef, aragonite, calcification, coral reef; environmental disturbance, in situ measurement, laboratory method, mesocosm, open ocean, physiological response, population decline
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical oceanography
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Effects of climate change on Australia (excl. social impacts)
UTAS Author:Tilbrook, B (Dr Bronte Tilbrook)
ID Code:80645
Year Published:2012
Web of Science® Times Cited:150
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2012-11-06
Last Modified:2017-10-31
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