Experimental study of cadmium bioaccumulation in three Mediterranean marine bivalve species: correlation with selected biomarkers

An ecotoxicological study is presented, in which three marine bivalve species (Mytilus galloprovincialis, Callista chione, and Venus verrucosa) living in different habitats were studied for Cd bioaccumulation, under laboratory conditions. The bivalves, originating from a relatively polluted marine area of Greece (Saronicos Gulf), were exposed to 0.5 mg Cd L–1 seawater (4.4 mol Cd L–1 seawater) for 5, 10, 15, and 20 days. Control animals were kept in metal-free seawater as well. Three or four different parts of the organisms (gills, mantle, body, digestive system) were examined for the bioaccumulation of Cd, as well as the levels of three biomarkers (metallothioneins, acetylcholinesterase, lipid peroxidation). A depuration experiment was also carried out. During the experiment, the initial levels of Cd in the control animal tissues either decreased or remained constant and low. The organisms exhibited different behavior regarding Cd bioconcentration and biomarker responses as well as tissue distribution of Cd. After the depuration period, significant amounts of Cd remained in the organisms’ tissues, much higher than the respective levels in control animals