Modelling the PCB bioaccumulation in the hake Merluccius

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Modelling the PCB bioaccumulation in the hake (Merluccius merluccius) from the Gulf of Lions

Modelling the PCB bioaccumulation in the hake (Merluccius merluccius) from the Gulf of Lions (Mediterranean sea) X. Bodiguel 1, V. Loizeau 1, C. Mellon 2, F. Ferraton 2 1 IFREMER, BP 70, 29280 Plouzané, France ; 2 IFREMER, B. P. 171, Av. J. Monnet 34203 Sète Cedex France [email protected] fr Objectives l To evaluate the PCB contamination in hakes from the Gulf of Lions. l To establish the bases of a bioaccumulation model of PCBs in a female hake. Study area Introduction Rhône river Polychlorinated Biphenyls (PCBs), are characterized by a high persistence in the environment, bioaccumulation by the marine organisms and potentially toxic character. Bioaccumulation depends on physical and chemical properties of the compounds and biological factors like feeding, growth and reproduction. At the top of a complex trophic web, the Mediterranean hake (Merluccius merluccius; L, 1758) is potentially exposed to these contaminants and it is significant to evaluate its contamination level and contamination mechanisms. Sector 2 Sector 1 Lion Golfe Gulf ofdu Lion Gulf of Lions • • 44 liver analyses (individuals from 10 to 34 cm) 17 PCBs congeners (CBs) by GC – ECD. Major occurrence of CB 153 and CB 138 Results PCB Analysis Evaluate the fate of PCBs in hakes from the gulf of Lions. Important presence of DDE (metabolite of DDT) • • CB 153 : 230 to 1700 ng. g-1 DW (for a juvenile hake of 11, 5 cm and a male adult of 34 cm) Concentrations 5 to 8 times higher than in hakes from the Bay of Biscay No influence of the Rhone river between the two studied areas High inter-individual variability, probably due to their physiological properties. Assumptions explaining the variations: • • PCB chromatogram in a male hake liver of 34 cm. CB 153 concentration in the hake livers function of their length Hake lenght (growth) Hake sex Sexual maturation degree Diet evolution Quantify the contribution and elimination of CB 153 during all the life of a female hake. Uptake : food Losses : excretion, spawning, dilution by growth. Principle Objective Modelling the PCB bioaccumulation (Dynamic Energy Budget approach) Growth model Coupled contaminant model • Foodcontainedenergyisassimilatedproportionallyto the hake surface area and stocked in the energy storage compartment (constant efficiency). • PCB allocation is described likely and proportionally to the fixed energy allocation • PCB food content varying with hake diet • Stored PCB are allocated to somatic and gonadic compartments, proportionally to the energy flow to biovolume and gonads respectively. PCB mobilisation from reserves is function to the PCB storage concentration. Conceptual diagram Results • • PCBs are expulsed during the annual spawning. • Forcing variable : - PCB prey concentration - Energy prey value. The comparison between growth model outputs and hake weight and length measurements validates the growth model during the whole life of a female hake. The PCB bioaccumulation simulation seems to be acceptable compared to the few analysis results. Conclusions ü Mediterranean hakes are significantly contaminated by PCBs. This contamination seems to be correlated according to growth, probably with the diet evolution and maturation degree. ü The bioaccumulation model simulates rather well the growth and contamination of an immature hake female. Future model development: • • • Taking into account bio-transformation. Validation for other PCB congeners and other contaminants (Hg). Extension to male hakes. Extension to the hake population and its trophic web. Contribution of contamination by water during breathing.