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Marine Ecology Progress Series

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MEPS 390:27-37 (2009)  -  DOI:

Trophic typology of coastal ecosystems based on δ13C and δ15N ratios in an opportunistic suspension feeder

S. Lefebvre1,3,*, C. Harma1, J.-L. Blin2

1UMR 100 IFREMER-Université de Caen Basse-Normandie ‘Physiologie et Ecophysiologie des Mollusques Marins (PE2M)’, Laboratoire de Biologie et Biotechnologies Marines, Esplanade de la Paix, B.P. 5186, 14032 Caen Cedex, France
2Syndicat Mixte pour l’Équipement du Littoral (SMEL), 50560 Blainville sur Mer, France
3Present address: Université des Sciences et Technologies de Lille – Lille 1, CNRS, UMR 8187 Laboratoire d’Océanographie et de Géoscience, Wimereux Marine Station, 28 av. Foch, 62930 Wimereux, France

ABSTRACT: Our objective was to use stable carbon (C) and nitrogen (N) isotope ratios of the adductor muscles of cultured Crassostrea gigas to typify the trophic state of temperate coastal ecosystems. Young oysters were introduced on a regional geographical scale in 8 locations along the coast of Normandy (France) and sampled after 9 mo in cultivation. Food sources were also investigated using a mixing model based on food source isotopic composition data previously obtained. To strengthen the interpretation of trophic ecosystem functioning, values of stable isotope ratios were combined with environmental variables in a principal component analysis (PCA). Isotopic values of adductor muscles varied significantly between –19.94 and –17.26‰ for δ13C and between 7.73 and 12.14‰ for δ15N. PCA discriminated 2 groups of coastal ecosystems that differed in coastal hydrology, inputs of nutrients, and size of their respective watersheds. Our results suggest that isotopic signature differences between these 2 spatial groups appeared too important to be due to (1) variations in the isotopic ratios of food sources and (2) differing trophic step fractionation between locations. These differences are more probably linked with differences in oyster diets. Finally, we conclude that cultured C. gigas is a useful spatial bio-indicator of coastal ecosystem trophic functioning in temperate ecosystems and an interesting biological model for the determination of isotopic baselines.

KEY WORDS: Crassostrea gigas · Marine · Carbon and nitrogen stable isotopes · Trophic web · Isotopic baseline · Aquaculture · Oyster

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Cite this article as: Lefebvre S, Harma C, Blin JL (2009) Trophic typology of coastal ecosystems based on δ13C and δ15N ratios in an opportunistic suspension feeder. Mar Ecol Prog Ser 390:27-37.

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