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Effects of dissolved organic carbon on the toxicity of copper to the developing embryos of the pacific oyster ( Crassostrea gigas )
Author(s) -
Brooks Steven J.,
Bolam Thi,
Tolhurst Laura,
Bassett Janice,
Roche Jay La,
Waldock Mike,
Barry Jon,
Thomas Kevin V.
Publication year - 2007
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/06-460r1.1
Subject(s) - copper , oyster , ec50 , chemistry , crassostrea , toxicity , environmental chemistry , dissolved organic carbon , copper toxicity , pacific oyster , nuclear chemistry , biology , ecology , biochemistry , organic chemistry , in vitro
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 with a hanging mercury drop electrode was used to measure the copper species as labile copper (LCu; free ion and inorganic copper complexes) and total copper (TCu) with respect to increasing HA concentration. The TCu and LCu 50% effect concentrations (EC50s) in the absence of HA were 20.77 μg/L (95% confidence interval [CI], 24.02–19.97 μg/L) and 8.05 μg/L (95% CI, 9.6‐5.92 μg/L) respectively. A corrected dissolved organic carbon (DOC) concentration (HA only) of 1.02 mg/L was required to significantly increase the TCu EC50 to approximately 41.09 μg/L (95% CI, 44.27–37.52 μg/L; 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 LCu EC50, 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.