Antoine Emmery

Address: UMR 100 Ifremer-UCBN PE2M, "Physiologie et Ecophysiologie des Mollusques Marins", Laboratoire de Biologie et Biotechnologies Marines, IBFA-Université de Caen, Esplanade de la paix, 14032 Caen cedex, Fance
Phone: +33(0)2 31 56 52 95
C. Vitae:
Specialization: eco-physiology
Courses: Dynamic Energy Budget theory

Growth variability of the Pacific oyster: IsoDEB

The main aim of this PhD project is to build up a scientific tool, allowing to better understand the variabilities in growth performances of the Pacific oyster Crassostrea gigas, integrating spatio-temporal environmental fluctuations (temperature, quantity and quality of tophic resources). This tool will consist in an individual bioenergetic model, called IsoDEB. This model will be build from the association of the DEB theory (Dynamic Energy Budget) and the stable isotopes assumptions (carbon and nitrogen stable isotopes). Coupling carbon and nitrogen stable isotopes as biomarker with the DEB model will allow us to trace and quantify the use and fate of organic matter from food sources till its integration in the C. gigas soft tissue. Stable isotope analysis will also provide more relevant scientific knowledge for characterizing the potential food sources and their contribution in the C. gigas diet. The IsoDEB model will therefore allow to take into account the evolution of isotopes fractionation and composition on individual soft tissue and to reconstruct and trace the quantitative and qualitative trophic history (using inverse analysis) responsible for this isotopes composition.

The model will be build firstly using existing data from literature and then an experimental approach will permit to test and validate the model. This experiment will also serve as a support to estimate a fractionation factor value function of controlled condition (e.g. temperature and food sources). Chosen factors could be manipulated to test the model behaviour and if necessary could be used to calibrate it. Isotope analyses on food sources and on the oyster tissues (whole individual and separate organs) will be made to trace the isotopic food signal from source until their assimilation in individual soft tissues. At the same time a large-scale in situ monitoring of C. gigas populations will be carried out to exploit IsoDEB potentialities as an operational tool for shellfish aquaculture. Biological descriptors (e.g. mass, shell length of oyster but also isotopic composition of specific organs as digestive gland, gonad, muscle) and environmental factors (e.g. temperature, salinity, food concentration) will be monitored at three geographically different sites over two years. The data set obtained in this way will be used for i) reconstructing the trophic history of oysters using the IsoDEB tool in inverse method and ii) for explaining the growth variability observed in C. gigas between culture sites or years. Thus, IsoDEB will provide management information for the shellfish industry via the characterisation of the different oyster-growing areas.

Abstracts and posters

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