Bioaccumulation and maternal transfer of copper in the freshwater snail Planorbella pilsbryi

Exposure of parents to a contaminant can lead to the transfer of a fraction of the contaminant accumulated in the parental tissues to the developing embryos. This study assessed the rate of uptake and rate of depuration of the metal copper in mature adults of the freshwater pulmonated gastropod Planorbella pilsbryi to calculate a kinetic bioconcentration factor. The kinetic bioconcentration factor of copper in P. pilsbryi was 4.36 ± 0.14. The resultant time to 95% depuration was 25.72 days. The study also assessed the maternal transfer of copper from mature adults to their egg masses. An elevated concentration of copper was measured in egg masses laid by mature adult snails exposed to 27.3 µg/L of copper for 7 days compared to the concentration measured in egg masses from unexposed adults. The concentration of copper in egg masses laid by adults in the second 7-day exposure were greater than the concentration in egg masses laid in the first 7-day exposure. The concentration of copper in egg masses laid after the adult snails were transferred to clean water returned to the baseline concentrations observed in adult snails that were not exposed to copper. This study provides evidence that snails transfer a fraction of copper taken up in their tissues to their egg masses following exposure, but the transfer ceases when exposure to the adults is discontinued. This information is critical to designing the appropriate study to accurately assess the potential transgenerational effects of contaminants on freshwater gastropods.