You are at :

2011

Effects of in vivo chronic exposure to hydrocarbons or pesticides on sanitary status and immune system in fish / Morgane Danion

Thesis jointly supervised by ANSES (French Agency for Food, Environmental and Occupational Health & Safety), laboratory of Ploufragan in Plouzané. PhD jointly supervised by: Claire Quentel

Committee: Jean LAROCHE, François SICHEL, Thierry CAQUET, Stéphane LE FLOCH, Tristan RENAULT, GILLES SALVAT

Abstract: The ecotoxicity of hydrocarbons and pesticides, was investigated in adult fish at in vivo exposure concentrations similar to those found chronically in the natural environment. The sanitary status, i.e. the health status of fish, with regard to chemical pollution and physiological status, was evaluated in sea bass, Dicentrarchus labrax exposed to a mixture of hydrocarbons using the water soluble fraction of crude oil and in rainbow trout, Oncorhynchus mykiss, contaminated by an active substance present in pesticide, pendimethalin. The pollutant molecules were quantified both in the exposure water and the fish (muscle and bile), confirming the efficiency of the experimental systems used. Chronic exposure to these pollutants deteriorates sanitary status in fish, increasing the potential risk for the health of human consumers. In addition, the health of fish assessed by monitoring several physiological, biochemical and immunological parameters was shown to be disturbed. Indeed, leucopenia due to lymphopenia and a decrease in phagocytic activity were observed in fish whatever the experimental exposure conditions, affecting innate and adaptive immunity. Following the infectious challenge with the viral hemorrhagic septicemia virus, pendimethalin seemed to accelerate fish mortality and a high number of seropositive fish was recorded compared to the group of control fish. Finally, these effects were observed at exposure levels below the currently estimated predicted no-effect concentrations (PNEC), highlighting the importance of taking into account sanitary status and the components of the immune system in aquatic organisms when establishing environmental quality thresholds.

Bibliographical reference: http://doc.cedre.fr/index.php?lvl=notice_display&id=9281

Response technique for oil spill and environmental risk: toxicity of dispersant application in nearshore area upon Liza aurata / Thomas Milinkovitch

Thesis jointly supervised by the University of La Rochelle. PhD jointly supervised by: Hélène Tomas-Guyon, UMR6250 LIENSs (LIttoral ENvironment and Societies) in La Rochelle

Committee: Thierry Caquet, Michel Warnau, Paco Bustamante, Eric Feunteun, Véronique Loizeau, Lionel Camus, Stéphane Le Floch

Abstract: Dispersant application is an oil spill response technique which accelerates the dispersion of petroleum from the sea surface into the water column by inducing the formation of oil droplets. In coastal areas this response technique is controversial since the low water depth reduces the dissemination of oil droplets and by the way increases the exposure of aquatic ecosystems to petroleum. To evaluate the toxicity of dispersant application in nearshore areas, an experimental approach was conducted. Juvenile of Liza sp. were exposed to three scenarios of contamination: (i) to chemically dispersed oil - simulating, in vivo, dispersant application ; (ii) to mechanically dispersed oil - simulating, in vivo, natural dispersion due to meteorological conditions ; (iii) to an undispersed oil slick simulating, in vivo, oil slick confinement as a response technique. Toxicity of each condition of exposure was evaluated through the mortality upon a group of individuals, through the swimming performance and the metabolic scope at the organism level, and through the measurement of biomarkers at the organ level.Comparison between an undispersed oil slick and a chemically dispersed oil slick shows that dispersant application induces an increase of the mortality and decreases the ability of the animal to cope with environmental contaminants (deduced from gill and liver total glutathione rate). Conversely, comparison between both a mechanically and a chemically dispersed oil slick, suggests that, when sea water is under mixing processes, dispersant application does not enhance petroleum toxicity. Taken together these results suggest that (i) an oil slick must not be dispersed when recovery can be conducted; (ii) dispersant application could be considered as a response technique when meteorological conditions are appropriated.

Bibliographical reference: http://doc.cedre.fr/index.php?lvl=notice_display&id=8547