Organochlorines in the Vaccarès Lagoon trophic web (Biosphere Reserve of Camargue, France).

During a decade (1996-2006), ecotoxicological studies were carried out in biota of the Vaccarès Lagoon (Biosphere Reserve in Rhone Delta, France). A multicontamination was shown at all levels of the trophic web due to a direct bioconcentration of chemical from the medium combined with a food transfer. Here, the pollutants investigated were organochlorines, among which many compounds banned or in the course of prohibition (or restriction) (PCB, lindane, pp'-DDE, dieldrin, aldrin, heptachlor, endosulfan...) and some substances likely still used in the Rhone River basin (diuron, fipronil). The results confirmed the ubiquity of contamination. It proves to be chronic, variable and tends to regress; however contamination levels depend on the trophic compartment. A biomagnification process was showed. A comparison of investigation methods used in other Mediterranean wetlands provides basis of discussion, and demonstrates the urgent need of modelling to assess the ecotoxicological risk in order to improve the management of such protected areas.

Assessment of the environmental quality of French continental Mediterranean lagoons with oyster embryo bioassay.

In order to better understand environmental disturbances in the French coastal Mediterranean lagoons, we used an ecotoxicological approach based on the measurement of the toxicity of the sediments using oyster embryo bioassay that provides a basis for assessing the effects on the fauna of contaminants adsorbed on the sedimentary particles. The study covers all of the main lagoons of the French Mediterranean coasts of Languedoc Roussillon, Camargue, and Provence (Berre and Bolmon lagoons), where 188 stations were sampled. The toxicity tests provide evidence of variable levels of toxicity in sediments. Contaminated lagoons such as La peyrade, Le canet, and Ingrill and locally affected lagoons such as Bages-Sigean, Vaccares, Bolmon, and Berre have sampling stations with 100% of larval abnormalities during 24-h development. In all of the lagoons, the toxicity was mainly located close to local harbors and rivers. Salses Leucate (Languedoc roussillon) lagoon was found very clean, with no important toxicity. The results are discussed in terms of environmental disturbances of the coastal lagoons and with regard to the long-term monitoring of the impact of contaminants on the coastal environment.

Rice fields regulate organochlorine pesticides and PCBs in lagoons of the Nature Reserve of Camargue.

In order to assess pollutant transfer in Camargue ponds from bordering agrosystems, a biomonitoring assay was conducted in irrigation and drainage channels of rice fields in the Rhone Delta (France). A filter-feeding bivalve, the Asian clam, Corbicula fluminea, was used as bioindicator and caged in upstream and downstream channels of an area of conventional rice fields. After 6 weeks incubation, many lipophilic biocides were identified in Corbicula tissues, including pesticides used in rice plantations (pretilachlor, oxadiazon), pesticides presumed in use in the Rhone basin [diuron and its metabolite 3,4 dichloroaniline (3,4-DCA)] and organochlorine pesticides (OCPs) banned for several decades. In addition, PCBs were highly bioaccumulated in Corbicula. Downstream bivalves had significantly lower concentrations of OCPs, PCB and 3,4-DCA. However, the exposure biomarkers (glutathione S-transferase, catalase and propionylcholinesterase) were not correlated with the decreased concentrations. The results of this experiment raise several questions concerning the potential role of immersed plants in a retention process.

Bioaccumulation of polychlorinated biphenyls in the eel (Anguilla anguilla) at the Camargue Nature Reserve - France.

Fish consumption is a potential source of human exposure to pollutants. Here, we study residue levels of PCBs in the eel, Anguilla anguilla, from the Nature Camargue Reserve in southern France. Chromatographic analysis (GC-ECD) found seventy identifiable congeners, among which, 10 are considered as dioxin-like PCBs, such as the non-ortho PCB 81 and the mono-ortho chlorobiphenyls PCB105, 114, 118, 123, 156, 157, 167, 170, 180. Toxic Equivalents (TEQ, WHO 2005 TEF-Toxic Equivalent Factors) varied among sites with a maximum in eels from Mornès (29.6pgg(-1) dry weight). Indicator PCBs (28, 52, 101, 118, 138, 153 and 180) were 22% and 29% of the total PCBs in livers and muscles respectively. Greater homogeneous bioaccumulation in muscle than that in liver suggests an increase risk for humans due to fish consumption.