RESEARCH ARTICLE Reprotoxicity of the Antifoulant

Chlorothalonil is a widely used biocide in antifouling paint formulation that replaces tin-based compounds after their definitive ban. Although chlorothalonil inputs into the marine environment have significantly increased in recent years, little is known about its effect on marine animals and in particular on their reproductive processes. In this line, the aim of the present study was to investigate the effects of chlorothalonil exposure on the gamete physi-ology, fertilization rate and transmissible damage to offspring in the marine invertebrate Ciona intestinalis (ascidians). To identify a possible mechanism of action of chlorothalonil, electrophysiological techniques were used to study the impact on oocyte membrane excit-ability and on the electrical events occurring at fertilization. The pre-exposure of spermato-zoa and oocytes to chlorothalonil did not affect the fertilization rate but caused damage to the offspring by inducing larval malformation. The highest toxicity was observed when fertili-zation was performed in chlorothalonil solutions with the lowest EC50 value. In particular, it was observed that low chlorothalonil concentrations interfered with embryo development and led to abnormal larvae, whereas high concentrations arrested embryo formation. In ma-ture oocytes, a decrease in the amplitudes of the sodium and fertilization currents was ob-served, suggesting an involvement of plasma membrane ion currents in the teratogenic mechanism of chlorothalonil action. The risk estimation confirmed that the predicted no-ef-fect concentration (PNEC) exceeded the predicted effect concentration (PEC), thus indicat-ing that chlorothalonil may pose a risk to aquatic species