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Geographical variation in thermal tolerance within Southern Ocean marine ectotherms

By Simon Anthony Morley, timo hirse, hans-otto poertner and Lloyd Peck

Abstract

Latitudinal comparisons of the Southern Ocean limpet, Nacella concinna, and clam, Laternula elliptica,\ud acclimated to 0.0 °C, were used to assess differences in thermal response to two regimes, 0.0, 5.1 to 10.0 °C\ud and 2.5, 7.5 to 12.5 °C, raised at 5.0 °C per week. At each temperature, tissue energy status was measured\ud through a combination of O2 consumption, intracellular pH, cCO2, citrate synthase (CS) activity, organic acids\ud (succinate, acetate, propionate), adenylates (ATP, ADP, AMP, ITP, PLA (phospho-L-arginine)) and heart rate.\ud L. elliptica from Signy (60°S) and Rothera (67°S), which experience a similar thermal regime (−2 to +1 °C)\ud had the same lethal (7.5–10.0 °C), critical (5.1–7.5 °C) and pejus (b5.1 °C;=getting worse) limits with only\ud small differences in biochemical response. N. concinna, which experiences a wider thermal regime (−2 to\ud +15.8 °C), had higher lethal limits (10.0–12.5 °C). However, at their Northern geographic limit N. concinna,\ud which live in a warmer environment (South Georgia, 54°S), had a lower critical limit (5.1–10.0 °C; O2, PLA\ud and organic acids) than Rothera and Signy N. concinna (10.0–12.5 °C). This lower limit indicates that South\ud Georgia N. concinna have different biochemical responses to temperatures close to their thermal limit, which\ud may make them more vulnerable to future warming trend

Topics: Marine Sciences, Biology and Microbiology
Publisher: Elsevier
Year: 2009
DOI identifier: 10.1016/j.cbpa.2009.02.001
OAI identifier: oai:nora.nerc.ac.uk:9662

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