Flounder health status in the Seine Bay. A multibiomarker study

The Seine Bay is used as a pilot area to assess the usefulness of monitoring programmes using a suite of biological measurements. These biomarkers included ethoxyresorfin-O-deethylase (EROD) and acetylcholinesterase (AChE) activities, multixenobiotic resistance (MXR) protein expression level assessment and gonad histopathology. Samples of European flounder collected in three sites close to the Seine Estuary in late September 1998 showed that 8% of the males were intersex, i.e. had gonads with both male and female tissues. Another 10% of individuals, identified as male by morphological observation during sampling, showed only female tissues on histological sections. These dramatic changes were associated with different patterns of EROD activity, MXR expression or AChE activity inhibition that might reflect shorter time effects of xenobiotics and constitute a starting point to integrate biological responses for the assessment of the health status of flounder in the Seine Bay.