The Toxicity of Copper to Pacific Oyster and Sea Squirt from Japan Using Regional Seawater as a Test Medium

Copper (Cu) toxicity is an increasing concern in marine environments; however, its effects are spe cies- and area-specific. In this study, area-specific Cu toxicity test was conducted on the sensitive early life stages ( i.e. , embryonic and larval development) of two important fisheries species, namely, Pacific oyster ( Crassostrea gigas ) and sea squirt ( Halocynthia roretzi ) using natural sea waters collected from three sites in the coastal area of Miyagi Prefecture, Japan. Measured concentrations for C. gigas and nominal concentrations for H. roretzi were used to calculate effect concentrations for each species. The 10% effect concentration (EC10) for Cu were 12.8–17.0 and 15.0–22.0 µg L −1 , and 50% effect concentration (EC50) for Cu were 20.3–22.6 and 45.6–47.2 µg L −1 , respectively. Notably, this study is the first to determine the toxicity of Cu to H. roretzi, and our results can provide additional information to strengthen the Cu species sensitivity distribution of saltwater species, which can support bioavailability correction. Moreover, the results of this study can help policymakers to develop more realistic Cu water quality standard while considering the effects of Cu toxicity on important species and the water chemistry in specific regions. (c)