Ecotoxicity test of copper to larvae of Ezo abalone using regional seawater as a test medium

Abstract

The ecotoxicity of copper (Cu) in the marine environment is of increasing concern. An understanding of benefits and risks in the use of Cu in Japanese coastal areas, particularly information of Cu effects on native copper-sensitive organisms is urgently required. In this study, we conducted ecotoxicity tests on the sensitive early life stages of local abalone (Haliotis discus hannai) using seawater collected from their natural habitat in Miyagi Prefecture, Japan. The no observed-effect concentration (NOEC), 10% effect concentration (EC10), and 50% effect concentration (EC₅₀) for Cu were determined to be 3.5, 5.8, and 8.6 µg/L, respectively. To account for bioavailability, we calculated the EC10 using the correction formula for dissolved organic carbon (DOC) provided in the Voluntary Risk Assessment Report of the European Chemical Agency, using literature values for DOC specific to the Japanese coastal area. As a result, the EC10 ranged from 3.2 to 11.7 µg/L. These results are important for policy makers to establish more realistic Cu water quality standards that take into account the effects on key species and the diverse characteristics of different regions within Japanese coastal areas.