Cytosolic distribution of Cd, Cu and Zn, and metallothionein levels in relation to physiological changes in gibel carp ( Carassius auratus gibelio) from metal-impacted habitats

Abstract

In the present study the impact of environmental metal contamination in gibel carp ( Carassius auratus gibelio) was investigated coupling disturbances in subcellular metal distribution to effect biomarkers. Gibel carp were caught at six different sampling sites in Flanders (Belgium), characterized by different degrees in environmental metal contamination. Tissue Cd, Cu and Zn concentrations and total metallothioneon (MT) levels were determined in gills, liver and kidney. Cytosolic metal distribution was measured in the main accumulating organs, liver and kidney, revealing tissue- and metal-dependent profiles. The MT pool dominated the cytosolic distribution profile. Although the importance of the MT pool increased with increasing environmental and cytosolic metal concentrations, also an undefined fraction of Cu and Cd fractions (probably free metal ions or metals bound to small organic complexes) increased at the most contaminated sampling sites. Disturbances in serum ion concentrations, serum alanine aminotransferase activity (ALT), hematocrite and condition factor were measured, as indicators of toxic effects. At the sampling site with the highest environmental Cd pollution a significant decrease in serum Ca 2+ concentrations and a significantly increased serum ALT activity were measured suggesting incomplete detoxification of Cd. Increased serum ALT concentrations suggested structural liver damage. The fact that the liver tissue, and probably also the kidney, could not cope with this high Cd burden in combination with the increased uptake of dissolved Cd through the gills most probably contributed to the perturbed serum Ca 2+ homeostasis.