The role of CO2 variability and exposure time for biological impacts of ocean acidification

Authors

  • Emily C. Shaw,

    Corresponding author
    1. Climate Change Research Centre, Faculty of Science, University of New South Wales, Kensington, New South Wales, Australia
    2. Now at School of Geography, Planning and Environmental Management, University of Queensland, Brisbane, Queensland, Australia
    • Corresponding author: E. Shaw, School of Geography, Planning and Environmental Management, University of Queensland, Brisbane, QLD 4072, Australia. (e.shaw5@uq.edu.au)

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  • Philip L. Munday,

    1. ARC Centre of Excellence for Coral Reef Studies and School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia
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  • Ben I. McNeil

    1. Climate Change Research Centre, Faculty of Science, University of New South Wales, Kensington, New South Wales, Australia
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Abstract

[1] Biological impacts of ocean acidification have mostly been studied using future levels of CO2 without consideration of natural variability or how this modulates both duration and magnitude of CO2 exposure. Here we combine results from laboratory studies on coral reef fish with diurnal in situ CO2 data from a shallow coral reef, to demonstrate how natural variability alters exposure times for marine organisms under increasingly high-CO2 conditions. Large in situ CO2 variability already results in exposure of coral reef fish to short-term CO2 levels higher than laboratory-derived critical CO2 levels (~600 µatm). However, we suggest that the in situ exposure time is presently insufficient to induce negative effects observed in laboratory studies. Our results suggest that both exposure time and the magnitude of CO2 levels will be important in determining the response of organisms to future ocean acidification, where both will increase markedly with future increases in CO2.

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