The toxicity of leather tannery effluent to a population of the blue mussel Mytilus edulis (L.)

The toxicity of leather tannery effluent affecting a population of Mytilus edulis in the Colligan estuary, Ireland was investigated. At the whole animal level, the growth, condition and chromium concentrations were measured in transplanted, local and control mussels. The fitness of the mussels was assessed by their tolerance to aerial exposure. At the cellular level, the degree of lipid peroxidation was measured in the tissues of field sampled mussels. In addition, mussels were exposed in the laboratory to components of the effluent thought likely to enduce peroxidation, i.e. Cr(VI), Cr(III)-protein and the fungicide, Busan 30WB® containing 2-(thiocyanomethylthio) benzothiazole (TCMTB). The growth, condition and chromium concentrations of transplanted mussels were significantly higher than controls after 1 year of exposure. The fitness of mussels at most sites in the Colligan estuary was comparable to the controls except those closest to the tannery outfall. At the cellular level, lipid peroxidation was demonstrated in the digestive cells of field sampled mussels, while in laboratory exposures Busan 30WB® was found to enduce lipid peroxidation in the digestive gland and amoebocyte proliferation in the gill. Cr(VI) and Cr(III)-protein exposure, by comparison, gave a negative peroxidative response. The results indicate that the enhanced growth and condition seen may be due to the high nutritive content of the effluent while the lipid peroxidation observed was reasoned to be a result of fungicide exposure. Chromium toxicity, however, could not be detected, although such an effect could not be ruled out.