University Of Tasmania
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Maximum thermal limits of coral reef damselfishes are size dependent and resilient to near-future ocean acidification

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journal contribution
posted on 2023-05-19, 14:58 authored by Clark, TD, Roche, DG, Binning, SA, Speers-Roesch, B, Sundin, J
Theoretical models predict that ocean acidification, caused by increased dissolved CO2, will reduce the maximum thermal limits of fishes, thereby increasing their vulnerability to rising ocean temperatures and transient heatwaves. Here, we test this prediction in three species of damselfishes on the Great Barrier Reef, Australia. Maximum thermal limits were quantified using critical thermal maxima (CTmax) tests following acclimation to either present-day or end-of-century levels of CO2 for coral reef environments (∼500 or ∼1,000 µatm, respectively). While species differed significantly in their thermal limits, whereby Dischistodus perspicillatus exhibited greater CTmax (37.88±0.03oC; N=47) than Dascyllus aruanus (37.68±0.02oC; N=85) and Acanthochromis polyacanthus (36.58±0.02oC; N=63), end-of-century CO2 had no effect (D. aruanus) or a slightly positive effect (increase in CTmax of 0.16oC in D. perspicillatus and 0.21oC in A. polyacanthus) on CTmax. Contrary to expectations, smaller individuals were equally as resilient to CO2 as larger conspecifics, and CTmax was higher at smaller body sizes in two species. These findings suggest that ocean acidification will not impair the maximum thermal limits of reef fishes, and they highlight the critical role of experimental biology in testing predictions of theoretical models forecasting the consequences of environmental change.


Publication title

Journal of Experimental Biology










Institute for Marine and Antarctic Studies


Company Of Biologists Ltd

Place of publication

Bidder Building Cambridge Commercial Park Cowley Rd, Cambridge, England, Cambs, Cb4 4Dl

Rights statement

Copyright 2017. Published by The Company of Biologists Ltd. Licensed under Creative Commons Attribution 3.0 Unported (CC BY 3.0)

Repository Status

  • Open

Socio-economic Objectives

Coastal or estuarine biodiversity