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First published online February 29, 2008
Journal of Experimental Biology 211, 969-977 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.014639

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Physiological and biochemical traits correlate with differences in growth rate and temperature adaptation among groups of the eastern oyster Crassostrea virginica

Fabrice Pernet^1,*, Réjean Tremblay², Iften Redjah^1,2, Jean-Marie Sévigny³ and Chantal Gionet¹

¹ Institut de Recherche sur les Zones Côtières, 232B rue de l'Église, Shippagan, Nouveau-Brunswick, Canada, E8S 1J2
² Institut des Sciences de la Mer, 310 allée des Ursulines, Rimouski, Québec, Canada, G5L 3A1
³ Institut Maurice-Lamontagne, Pêches & Océans Canada, Mont-Joli, Québec, Canada, G5H 3Z4

^* Author for correspondence (e-mail: fabrice.pernet{at}ifremer.fr)

Accepted 25 January 2008

We tested two hypotheses in this study: first, that intraspecific growth variations in a marine bivalve are correlated with physiological (basal metabolic rate and scope for growth) and biochemical (membrane lipids) characteristics, and, second, that this bivalve shows intraspecific variations in physiological and biochemical adaptations to temperature. To test these hypotheses, five genetically distinct groups of juvenile oysters Crassostrea virginica that showed differences in their growth rates were maintained in the laboratory (1) for further measurements of growth and standard metabolic rates and (2) subjected to acclimation at 4°C, 12°C and 20°C and further examined for scope for growth and determination of membrane lipid composition. Our results show that a lower basal metabolic rate and lower unsaturation index of membrane lipids coincides with higher growth rates and a higher scope for growth in oysters. We provide evidence that intraspecific differences in basal metabolic rate in oysters are related to membrane unsaturation as predicted by Hulbert's theory of membranes as metabolic pacemakers. Furthermore, our results suggest that the theory of membranes as metabolic pacemakers is related to intraspecific differences in growth. A perfect negative relationship was observed between the acclimation temperature and the unsaturation index of membrane lipids in oysters, as predicted by the homeoviscous adaptation theory. However, changes in the unsaturation index in response to temperature were mainly due to variations in the eicosapentaenoic (20:5n-3) fatty acid in fast-growing oysters, whereas slow-growing animals changed both docosahexaenoic acid (22:6n-3) and 20:5n-3. Thus, the pattern of biochemical compensation in response to temperature in this species shows intraspecific variation.

Key words: genetically based intraspecific variation, growth, temperature adaptation, scope for growth, lipid remodelling, homeoviscous adaptation, mollusc, aquaculture

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