Effects of subchronic exposures of world wide used herbicides on two economically important mollusc species. In vitro approach in the abalone, Haliotis tuberculata and in vivo approach in the cupped oyster, Crassostrea gigas.

• Main Author: Mottier, Antoine
• Other Authors: Biologie des mollusques marins et des écosystèmes associés (BioMEA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS), Région Basse-Normandie, Université de Caen Basse-Normandie, Katherine Costil, European Project: CHRONEXPO
• Format: Thesis
• Language: French
• Published: HAL CCSD 2013
• Subjects: Crassostrea gigas; Haliotis tuberculata; ecotoxicology; herbicides; glyphosate; Roundup; mecoprop; haemocytes; embryo-larval stages; juveniles; subchronic exposures; écotoxicologie; hémocytes; stades embryo-larvaires; expositions subchroniques; envir; socio
• Online Access: https://hal.archives-ouvertes.fr/tel-01153793/file/Manuscrit.pdf; https://hal.archives-ouvertes.fr/tel-01153793

This work aimed to assess the effects of world wide used herbicides on two economically important mollusc species : the abalone Haliotis tuberculata and the cupped oyster Crassostrea gigas. The researches dealt with in vitro and in vivo laboratory experiments. In vitro experiments on H. tuberculata haemocytes were performed in order to assess the effects of an active matter (glyphosate), a commercial formulation (Roundup express : REX) and a mixture of adjuvants (POEAs). Results showed a greater toxicity of exposures to REX and POEAs which appeared to act on biological membranes. In vivo experiments on C. gigas also clearly demonstrated the toxicity of commercial formulations and adjuvants. Bioassays on early life stages (D veliger and pediveliger) allowed us to assess the toxicity of a relatively large number of active matters (glyphosate, mecoprop, mecoprop-p), degradation compounds (AMPA, 2-MCP), commercial formulations (Roundup) and adjuvantmixture (POEAs). Results provided interesting information on the relative toxicity of the tested chemicals and showed the sensitivity of the earliest life stage (i.e. D veliger larvae). Long time exposures (up to 56 days) of C. gigas juveniles revealed an activation of the defense mechanisms at the molecular level but also physiological perturbations with a slowdown in growth and gametogenesis of oysters exposed to the lowest doses of Roundup and POEAs (i.e at the dose of 0.1μg/L which could be measured in the environment). Environmentally relevant doses of pesticides cannot lead to oyster mortality but could be considered as additional stressors during the periods prior to summer mortalities. Ce travail de thèse vise à étudier l’impact de molécules herbicides parmi les plus utilisées en France et dans le monde, sur deux espèces de mollusques exploitées : l’ormeau, Haliotis tuberculata et l’huître creuse, Crassostrea gigas. Les travaux ont porté sur des expositions réalisées en laboratoire et deux approches différentes ont été mises en oeuvre. Une première approche in ...