Influence of food quality and salinity on dietary cadmium availability in Mytilus trossulus

Surficial sediments (a combination of re-suspended and suspended sediments denoted as RSS) were collected from two distinct marine intertidal habitats. The two habitats differed with respect to salinity (25 ppt versus 15 ppt) and RSS % organic carbon content (24% versus 15%). Feeding experiments were conducted simulating the conditions in the two habitats to determine if salinity and RSS % organic carbon content affected cadmium accumulation in the pacific blue mussel Mytilus trossulus. Eleven different treatments including pure phytoplankton, collected RSS and control clay were radiolabeled with 109Cd and pulse-fed to M. trossulus under both high (25 ppt) and low salinities (15 ppt). Metal uptake and accumulation was determined using the DYMBAM biodynamic metal bioaccumulation model. Although M. trossulus ingestion rates (IR) were significantly higher at 25 ppt as compared to 15 ppt, assimilation efficiencies (AEs) and [109Cd] tissue levels were significantly lower at high as compared to low salinity exposures. Of the abiotic and biotic parameters examined and in contrast to other studies, differences in salinity rather than ingestion rate or food quality (as defined by % organic carbon content) seemed to best define the observed differences in 109Cd AE by M. trossulus.