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Marine invertebrate skeleton size varies with latitude, temperature and carbonate saturation: implications for global change and ocean acidification

Authors

  • Sue-Ann Watson,

    1. School Of Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton, ZH, United Kingdom
    2. British Antarctic Survey, Natural Environment Research Council, High Cross, Cambridge, United Kingdom
    3. School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia
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  • Lloyd S. Peck,

    Corresponding author
    1. British Antarctic Survey, Natural Environment Research Council, High Cross, Cambridge, United Kingdom
    • School Of Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton, ZH, United Kingdom
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  • Paul A. Tyler,

    1. School Of Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton, ZH, United Kingdom
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  • Paul C. Southgate,

    1. School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia
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  • Koh Siang Tan,

    1. Tropical Marine Science Institute, National University of Singapore, Singapore, Singapore
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  • Robert W. Day,

    1. Zoology Department, University of Melbourne, Parkville, Australia
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  • Simon A. Morley

    1. British Antarctic Survey, Natural Environment Research Council, High Cross, Cambridge, United Kingdom
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Correspondence:

Prof. Lloyd S. Peck, British Antarctic Survey, High Cross Madingley Road, Cambridge, CB3 0ET, UK, tel: ++ 44 01223 221 603, fax: ++ 44 01223 221 259, e-mail: l.peck@bas.ac.uk

Abstract

There is great concern over the future effects of ocean acidification on marine organisms, especially for skeletal calcification, yet little is known of natural variation in skeleton size and composition across the globe, and this is a prerequisite for identifying factors currently controlling skeleton mass and thickness. Here, taxonomically controlled latitudinal variations in shell morphology and composition were investigated in bivalve and gastropod molluscs, brachiopods, and echinoids. Total inorganic content, a proxy for skeletal CaCO3, decreased with latitude, decreasing seawater temperature, and decreasing seawater carbonate saturation state (for CaCO3 as calcite (Ωcal)) in all taxa. Shell mass decreased with latitude in molluscs and shell inorganic content decreased with latitude in buccinid gastropods. Shell thickness decreased with latitude in buccinid gastropods (excepting the Australian temperate buccinid) and echinoids, but not brachiopods and laternulid clams. In the latter, the polar species had the thickest shell. There was no latitudinal trend in shell thickness within brachiopods. The variation in trends in shell thickness by taxon suggests that in some circumstances ecological factors may override latitudinal trends. Latitudinal gradients may produce effects similar to those of future CO2-driven ocean acidification on CaCO3 saturation state. Responses to latitudinal trends in temperature and saturation state may therefore be useful in informing predictions of organism responses to ocean acidification over long-term adaptive timescales.

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