Publication Abstract

The effects of dissolved organic carbon on the toxicity of copper to the developing embryos of the Pacific oyster, Crassostrea gigas.

The effects of dissolved organic carbon on the toxicity of copper to the developing embryos of the Pacific oyster, Crassostrea gigas

S.J. Brooks, T. Bolam, L. Tolhurst, J. Bassett, J. La Roche, M. Waldock and K.V. Thomas.

The effects of humic acid (HA) on copper speciation and its subsequent toxicity to the sensitive early life stages of the Pacific oyster, Crassostrea gigas are presented. Differential pulse anodic stripping voltammetry at a hanging mercury drop electrode (DPASV-HMDE) was used to measure the copper species as labile (LCu, free ion and inorganic copper complexes) and total copper (TCu) with respect to increasing HA concentration. The TCu and LCu EC₅₀ values in the absence of HA were 20.77 µg l^-1 (24.02 – 19.97, 95% confidence limits (CL)) and 8.05 µg l^-1 (9.6 – 5.92, 95% CL) respectively. A corrected dissolved organic carbon (DOC) concentration (HA only) of 1.02 mg l^-1 C was required to significantly increase the TCu EC₅₀ to approximately 41.09 µg l^-1 (44.27 – 37.52, 95% CL) (p<0.05), almost doubling that recorded when DOC (as HA) was absent from the test media. In contrast, the LCu EC₅₀ was unaffected by changes in DOC concentration and was stable throughout the corrected DOC concentration range. The absence of change in the EC₅₀ of LCu despite increased HA concentration, suggests that the LCu fraction, not TCu, was responsible for the observed toxicity to the oyster embryo. This corresponds with the current understanding of copper toxicity and supports the free ion activity model for copper toxicity.

Reference:

S.J. Brooks, T. Bolam, L. Tolhurst, J. Bassett, J. La Roche, M. Waldock and K.V. Thomas. (2007) The effects of dissolved organic carbon on the toxicity of copper to the developing embryos of the Pacific oyster, Crassostrea gigas. Environmental Toxicology and Chemistry, 26: 1756-1763

S.J. Brooks*, T. Bolam*, L. Tolhurst*, J. Bassett*, J. La Roche*, M. Waldock*, J. Barry* and K.V. Thomas.

Environmental Toxicology and Chemistry, 26: 1756-1763