Inhibition of embryo development of the Mytilus galloprovincialis marine mussel by organic pollutants; assessment of risk for its extensive culture in the Galician Rias

This study evaluates the risk posed by selected organic pollutants on the culture of the marine mussel in the Galician coast (NW Iberian Peninsula), which depends on collection of natural seed in densely populated coastal areas. With this aim toxicity tests were carried out with embryos of the Mytilus galloprovincialis mussel, and the toxicity of the surfactant sodium dodecyl sulphate (SDS) and the biocides TBT, chlorpyrifos and lindane was quantified in terms of median effective concentration (EC50) and toxicity threshold (EC10 and LOEC), using embryogenesis success as end point. The EC10 and EC50 values were 161 and 377 ng/L for TBT, 79 and 154 µg/L for chlorpyrifos, 495 and 2353 µg/L for SDS, 1.41 and 1.99 mg/L for lindane. Toxicity thresholds for mussel embryos from this study and crustacean larvae from the literature were compared to environmental concentrations in coastal waters, either directly measured or estimated from mussel bioaccumulation data, in an attempt to evaluate the risk posed by those pollutants to these commercial species. It was concluded that SDS and, especially, chlorpyrifos and lindane, do not pose a threat to these commercial resources. In contrast, TBT risk quotients derived either from actual seawater measurements or mussel bioaccumulation data were both unacceptably high. TBT pollution represents thus a potential threat to natural availability of spat, the basis of extensive mussel culture. At the light of the data presented, current TBT seawater quality criterion seems underprotective and it should be revised.