Cadmium, lead and metallothionein contents in tissues of the sea bream Sparus aurata from three different fish farming systems

Heavy metals in marine environment have a particular significance in ecotoxicology, since they are highly persistent and can be toxic in traces. Metals such as Pb and Cd are potentially toxic and pose a serial risk for human health when they enter the food chain. Fish are exposed to metals at different intensities through two major routes: metal ions dissolved in the water can be absorbed through the gills; metals bound to solid particles can be ingested and absorbed through the gut epithelium. For farmed fish, growing conditions (food and water chemistry) may determine metal composition of fish tissues as well as the response that these fish exhibit to metal toxicity. The distribution and bioaccumulation of dietary and waterborne cadmium and lead in tissues of sea bream Sparus aurata was studied in relation to three different fish farming systems. Metallothionein levels in fish tissues were also evaluated.