Antifouling biocides: Impairment of bivalve immune system by chlorothalonil

Marine ecosystems are subjected to a variety of contaminants. Antifouling paints, for example, have been extensively used to protect ship surfaces from marine biofouling, but their toxicity has generated great concern. Thus, we evaluated the effect of the biocide chlorothalonil on the immune system of Perna perna mussels. The mussels were exposed to 0 (control), 0.1 μg/L and 10 μg/L of chlorothalonil for up to 96 h. After 24 h and 96 h of exposure, the following immune-related parameters were analyzed in the hemolymph of mussels: total hemocyte count, cell adhesion, phagocytic activity, level of reactive oxygen species, cell viability and comet assay. After 24 h and 96 h of chlorothalonil exposure, cellular adhesion increased and the hemocyte viability reduced. Moreover, an increase in phagocytic activity was also observed after 96 h of exposure to cholorothalonil. The exposure to 10 μg/L of chlorothalonil for 96 h reduced the air survival capacity of mussels. Total hemocyte count, ROS generation and DNA damage were not affected by the contaminant exposure. Our results indicate that chlorothalonil affected important immune responses of the bivalves, demonstrating that this biocide has effects on non-target species. This modulation of immune system reduced the health status of mussels, which could compromise their ability to survive in the environment.