According to Apte and Day (1998), pesticides used in grass and broadleaf weed control in agriculture or in antifouling boat paint are the most ecotoxicologically relevant to marine species. S-metolachlor is one of the most intensively used chloroacetamide herbicide in agriculture and is moderately toxic to freshwater and estuarine animals (Lizotte et al., 2009; Cook and Moore, 2008; Jin-Clark et al., 2008; Wan et al., 2006). For instance, the low acute toxicity of metolachlor exposure was found for Oncorhynchus sp. and Daphnia magna, with 24 h-LC50 values of 19,000–44,000 μg L−1 and 80,000 μg L−1, respectively. Metolachlor is regularly detected in European surface waters during the crop-growing season ( Buser et al., 2000). Diuron is a substituted urea herbicide and has been associated with general weed control on land. The use of this Amrubicin
as an herbicide has been restricted in France since 2002 (JO n°80 April 5, 2002). Diuron has also been used as an antifouling agent in many European countries ( Boxall et al., 2000; Martinez et al., 2001). This compound is commonly detected in areas of high boating or yachting activity and is considered to be relatively persistent in seawater ( Konstantinou and Albanis, 2004), with a slow breakdown (from one month to one year) ( Okamura, 2002) and half-lives of about 60 days ( Harino et al., 2005). In Dutch and British coastal areas, diuron is present at higher concentrations than irgarol and other biocides ( Lamoree et al., 2002; Thomas et al., 2002). Depending on the time or concentration of exposure and the considered species, diuron has shown toxic effects on various organisms such as algae, crustaceans
and fish ( Fernández-Alba et al., 2001, 2002; Okamura, 2002). Irgarol is a herbicidal additive used in copper-based antifouling paints and it is estimated that its overall residence time in the marine systems is over 10 years ( Ranke, 2002). If so, irgarol can be considered as a persistent organic pollutant. High levels of irgarol were reported in April–May when the high boating season starts at the west coast of Sweden ( Dahl and Blanck, 1996). Early studies reported that although irgarol was found to be highly toxic to algae and higher plants, as it is a potent inhibitor of photosynthesis ( Dahl and Blanck, 1996; Macinnis-Ng and Ralph, 2003; Nyström et al., 2002; Owen et al., 2002), it is comparatively less toxic to marine bacteria and crustaceans as well as in fish cell culture ( Okamura et al., 2000b, 2002). However, to our knowledge, the literature relating to the toxic effects of metolachlor, irgarol and diuron on marine invertebrate species, particularly the Pacific oyster, is still limited.