Level of contamination and impact of pesticides in cupped oyster, Crassostrea gigas, reared in a shellfish production area in Normandy (France)

Abstract

Over the last decade, oysters in the Bay of Veys (Northwest France) have sporadically experienced significant summer mortality events which appear to be due to a combination of extrinsic and intrinsic factors. In the present work, the involvement of pesticides (as additional stressors) was investigated using both artificial exposure and field studies (at two sites). Six herbicides were detected in seawater following tests for a total of 15 herbicides. The most estuarine site was the most contaminated, showing relatively high values compared with those recorded in a neighboring river. No pesticides were detected in the flesh of oysters in the field but exposure experiments led to an accumulation of two substituted ureas (diuron and isoproturon, from 0.5 μ g/L and 1 μ gL^{− 1} respectively). Some physiological effects were observed in terms of reproduction (partial spawning) and histopathology (atrophy of the digestive tubule epithelium) but results related to other tissue alterations and to neutral red retention (NRR) assays were not conclusive and require further investigation.

Keywords:

• Pacific oyster
• Normandy
• pesticides
• NRR assay
• histopathology
• gametogenesis

Acknowledgment

We thank the staff at the Laboratoire Départemental 14 Frank Duncombe, the Centre de Recherche en Environnement Côtier (CREC; Station Marine de Luc-sur-mer) and the LERN (IFREMER Port-en-Bessin) for technical facilities. Thanks are due to Béatrice Adeline for her technical assistance in histology. The authors are also grateful to Dr Helen McCombie for her linguistic guidance.

This paper was presented at the CEMEPE conference held on June 24–28, 2007 at the Skiathos Island, Greece.

Notes

*Limit of Quantification (LOQ): 0.010 μ gL^{− 1}.