|Influence of the trophic environment and metabolism on the dynamics of stable isotopes in the Pacific oyster (Crassostrea gigas): modeling and experimental approaches|
Emmery, M.A. (2012). Influence of the trophic environment and metabolism on the dynamics of stable isotopes in the Pacific oyster (Crassostrea gigas): modeling and experimental approaches. PhD Thesis. Université de Caen Basse-Normandie: Caen. 110 pp.
Animal metabolism; Food chain; Isotope effect; Marine invertebrates; Crassostrea gigas (Thunberg, 1793) [WoRMS]; Marine
Biological markers; Stable Isotope Ecology
Stable isotope analysis (SIA) contributed extensively to better understand the trophic functioning of marine coastal ecosystems. However, their ecological interpretations are limited by the lack of accurate modelling tools to describe the dynamics and the trophic fractionation of stable isotopes by organisms. The influence of the trophic resource and the metabolism on the dynamics of delta13C and delta15N in the soft tissues of the Pacific oyster Crassostrea gigas has been investigated using experimental and modeling approaches. The results of the in situ survey in the Bay of Veys and the Bay of Brest showed that growth (whole soft body tissues and organs) and the trophic resource (diversity and quantity) have to be considered simultaneously to accurately understand the temporal variations in delta13C and delta15N of oysters. Then, a model based on the Dynamic Energy Budget theory (DEB) has been developed and calibrated for this species. This approach showed that the higher the feeding level, the higher the growth and the lower the delta and ?. It also demonstrated that the anabolic and catabolic routes of the assimilation, growth and maintenance of the organism play a key role in the isotopic fractionation. The model also allows to calculate dynamically the trophic fractionation. The trends simulated by the model have been validated during the fractionation experiment at two feeding levels carried out on oysters. This type of model thus constitutes a relevant tool to characterized the variable trophic environment of marine bivalves.
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