Christophe Minier

Growth and condition of 0-group European flounder, Platichthys flesus as indicator of estuarine habitat quality

The purpose of this present study was to use the growth rates, RNA–DNA ratio and morphometric (Fulton’s K) condition indices measured on 0-group juveniles European flounder, as a means of comparing the quality of estuarine nursery habitats. The Seine estuary, heavily impacted by manmade modifications and one of the most contaminated in Europe, was compared to two smaller estuaries considered as clean (low domestic, agricultural and industrial effluents). Indicators of human disturbance (sediment chemical contaminants) as well as biotic data (macrobenthos abundances) were used to establish between-site differences in environmental quality. The abundance of macrobenthos (potential preys for juvenile) was high and not significantly different among the three estuaries confirming the important role played by estuaries as feeding grounds. Sediment metal concentrations (Cd, Cr, Cu, Pb, Zn) were significantly higher in the Seine than in the Canche and Authie estuaries. Otolith growth was closely related to somatic fish growth, and we used daily otolith increments from the previous 10xa0days before capture as an indicator of 0-group flounder recent growth (RG). RG did not vary significantly among flounders from the Canche and Authie estuaries and individuals from the Seine had slower RG. RNA–DNA ratio and K values were also significantly lower in individuals from the Seine compared to those of the Authie or the Canche. Pollution (e.g. metal contaminants) is the most likely cause of growth and condition differences among estuaries. The results of this study suggest that habitat-specific fish growth and condition are useful proxies for habitat quality since they integrate the effect of multiple environmental factors.

Endocrine disruption in wild populations of chub (Leuciscus cephalus) in contaminated French streams.

The aim of this study was to assess endocrine disruptive effects in wild population of fish in five French rivers selected to represent different pollution contexts at two seasons (summer and fall). For that purpose, a panel of biometrical parameters (length, weight, and gonado-somatic index: GSI) and biochemical (ethoxyresorufin-O-deethylase: EROD, vitellogenin: VTG, and brain aromatase) and histological biomarkers (gonads histology) were used in chub (Leuciscus cephalus), a common cyprinid fish species. In fish from the reference site, EROD activity and VTG levels were low at the two seasons. Brain aromatase activities (AAs) were similar to other species and increased with increasing GSI and gonad maturation. Among the four contaminated sites, the Jalle dEysines River was the most impacted site. At this site, fish were exposed to estrogenic substances as demonstrated by the VTG induction in males and the arrest of development of the gonads that led to lower brain AA compared to fish from the reference site. In fish from other contaminated sites, EROD activity was induced as compared to fish from the reference site and some males had elevated concentrations of VTG. Moreover, the presence of aromatase-inhibiting compounds was demonstrated in the sediments of three contaminated sites, even if the precise nature of contaminants is not known. This study provides new data concerning endocrine disruption in wild fish populations inhabiting French rivers and demonstrates that measurements of in vivo and in vitro aromatase could be used as biomarkers of endocrine disruption in field studies.

A multibiomarker approach in juvenile turbot, Scophthalmus maximus, exposed to contaminated sediments

Juvenile turbot were exposed in laboratory conditions to a mixture of chemical contaminants associated with harbour and estuarine sediments for seven and 21 days. Several molecular biomarkers of exposure were then measured in fish liver: two biotransformation parameters [ethoxyresorufin-O-deethylase (EROD) and phase II glutathione S-transferase (GST) activities] and an antioxidant enzyme activity [catalase (CAT)]. Modifications at the histological level were analysed by the measurement of the number and size of melanomacrophage centres (MMCs) and disturbances to the immune function by the measurement of cytokine transforming growth factor-beta (TGF-β) and development of the thymus. The responses of these molecular and immunological biomarkers were correlated with metal and PAH concentrations measured in sediments and with the physiological performance of turbot analysed in a previous study on the same fish (growth rates, condition factor K, RNA:DNA ratio and lipid index). While no difference was found in thymus analysis, some molecular and immunological responses were observed in fish exposed to contaminated sediments. Weak relationships between molecular biomarkers responses and PAH concentrations were recorded, while their responses were significantly correlated with some metals. MMC and aggregates were weakly related to chemical contaminants whereas some significant correlations were found between TGF-b1 responses and some metal concentrations. However, molecular and immunological biomarkers were weakly related to fish physiological damages since low responses were observed in the condition which led to the lowest growth and condition indices. These data suggest the complexity of cause-effect relationships between exposure to pollutants, metabolisms and health damages. Precautions should be considered in the use of molecular and immunological biomarkers alone in biomonitoring programs. Their complementary use with physiological biomarkers, such as fish growth and condition indices, could improve their utilisation.

Regulatory identification of BPA as an endocrine disruptor: Context and methodology

BPA is one of the most investigated substances for its endocrine disruptor (ED) properties and it is at the same time in the center of many ED-related controversies. The analysis on how BPA fits to the regulatory identification as an ED is a challenge in terms of methodology. It is also a great opportunity to test the regulatory framework with a uniquely data-rich substance and learn valuable lessons for future cases. From this extensive database, it was considered important to engage in a detailed analysis so as to provide specific and strong evidences of ED while reflecting accurately the complexity of the response as well the multiplicity of adverse effects. An appropriate delineation of the scope of the analysis was therefore critical. Four effects namely, alterations of estrous cyclicity, mammary gland development, brain development and memory function, and metabolism, were considered to provide solid evidence of ED-mediated effects of BPA.