Acute toxicity of some methylmercury complexes to Mytilus edulis and lack of selenium protection

Abstract

Laboratory experiments have been conducted to estimate the acute toxicity of three different chemical forms of methylmercury to Mytilus edulis. The possible antagonistic activity of dissolved inorganic and complexed organic selenium was also evaluated. The following findings were made: 1. several chemical forms of methylmercury, having different solubility in seawater, were absorbed by mussels, 2. the total mercury body burden was not influenced by dissolved Na 2SeO 3, and selenium was not significantly bioaccumulated despite its chemical form, 3. the high toxicity of all methylmercury complexes was indicated by a significant loss of animal weight and a relatively high cumulative mortality after 32 days of exposure to 3 μg Hg l −1, 4. selenium showed no evident antagonistic effect, but the relative proportion of mercury bioaccumulated in the mantle was slightly increased in the presence of dissolved sodium selenite in the flowing seawater. Two different chemical mechanisms of methylmercury assimilation are discussed.