Contrasting effects of constant and fluctuating pCO₂ conditions on the exercise physiology of coral reef fishes

Hannan, Kelly D., McMahon, Shannon J., Munday, Philip L., and Rummer, Jodie L. (2021) Contrasting effects of constant and fluctuating pCO₂ conditions on the exercise physiology of coral reef fishes. Marine Environmental Research, 163. 105224.

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Ocean acidification (OA) is predicted to affect the physiology of some fishes. To date, most studies have investigated this issue using stable pCO₂ levels based on open ocean projections. Yet, most shallow, nearshore systems experience temporal and spatial pCO₂ fluctuations. For example, pCO₂ on coral reefs is highest at night and lowest during the day, but as OA progresses, both the average pCO₂ and magnitude of fluctuations are expected to increase. We exposed four coral reef fishes - Lutjanus fulviflamma, Caesio cuning, Abudefduf whitleyi, and Cheilodipterus quinquelineatus - to ambient, stable elevated, or fluctuating elevated pCO₂ conditions for 9-11 days. Then, we measured swimming performance, oxygen uptake rates, and haematological parameters during the day and at night. When compared to ambient pCO₂ conditions, L. fulviflamma, C. cuning, and A. whitleyi exposed to fluctuating elevated pCO₂ increased swimming performance, maximum oxygen uptake rates, and aerobic scope, regardless of time of day; whereas, the only nocturnal species studied, C. quinquelineatus, decreased maximum oxygen uptake rates and aerobic scope. Our findings suggest that exposure to fluctuating or stable elevated pCO₂ can physiologically benefit some coral reef fishes; however, other species, such as the cardinalfish examined here, may be more sensitive to future OA conditions.

Item ID: 66106
Item Type: Article (Research - C1)
ISSN: 1879-0291
Keywords: Ocean acidification, Swimming, Oxygen uptake, Aerobic scope, Fluctuating CO2
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Copyright Information: © 2020 Elsevier Ltd. All rights reserved.
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A version of this publication was included as Chapter 4 of the following PhD thesis: Hannan, Kelly D. (2021) Effects of diel pCO₂ fluctuations on coral reef fishes now and into the future. PhD thesis, James Cook University, which is available Open Access in ResearchOnline@JCU. Please see the Related URLs for access.

Funders: Lizard Island Reef Research Foundation, Sea World Research and Rescue Foundation
Date Deposited: 17 Feb 2021 18:18
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 50%
41 ENVIRONMENTAL SCIENCES > 4101 Climate change impacts and adaptation > 410102 Ecological impacts of climate change and ecological adaptation @ 50%
SEO Codes: 18 ENVIRONMENTAL MANAGEMENT > 1805 Marine systems and management > 180504 Marine biodiversity @ 50%
19 ENVIRONMENTAL POLICY, CLIMATE CHANGE AND NATURAL HAZARDS > 1901 Adaptation to climate change > 190102 Ecosystem adaptation to climate change @ 50%
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