Mise en évidence et validation de biomarqueurs écotoxicologiques dans la population d’anguilles d’un étang de la Réserve Naturelle Nationale de Camargue, le Vaccarès, exposée à des polluants organiques persistants

Abstract

Though located in a rather remote area free from neighbouring industrial activities, the French National Nature Reserve of Camargue is however exposed to a non point source contamination by a number of persistant organic pollutants, particularly polycyclic aromatic hydrocarbons (PAH) and organochlorine compounds (OC) . Due to the nature of this contamination, investigations about validation of biomarkers in the eels of the Vaccarès lagoon have proven to be of the utmost importance. They have been focused on the characterization and validation of biomarkers related to metabolic responses including, not only the detoxification mechanisms (biotransformation, antioxidant process) and the energy requirements, but also some unspecific metabolic processes. These last ones are enzymatic membrane markers implicated either in the neuronal conduction (acetylcholinesterase, AChE) or in the osmoregulation and the energy metabolism (ATPases). The experimental results have been screened by the way of a multivariate analysis. It may be concluded that the rate of tissue glycogen seems to be a sensitive biomarker as well as three hepatic activities involved in the protection against oxyradicals : catalase, glutathion peroxidase (SeGPx) and superoxide dismutases (SOD). The muscle and gill ATPases as well as the muscle and brain AChE show more significant results in term of biomarkers than the biotransformation enzymes : ethoxyresorufine-O-deethylase (EROD) and uridine diphospho-glucuronyl transferase (UDPGT). However most of these enzymatic activities depend on a number of abiotic factors. This study brings some conclusive elements for the validation of the biomarkers use from data obtained in laboratory studies to their application in field ecotoxicology. It also raises the question about the tissue location of the contaminant in fish, in relationship to their age or their mode of contamination, and its influence on the biomarkers response. As a conclusion, if the validation of membrane indicators is confirmed, this study, by its innovative approach, provides the first statement on the extent of the ecotoxicological threat for the aquatic species in a protected area, stemming from the occurrence of persistent organic pollutants (POP) in the cell membranes.