Organochlorinated Pollutants and Xenobiotic Metabolizing Enzymes in W. Mediterranean Mesopelagic Fish

Polychlorinated biphenyl (PCB) congeners and pp′-DDT were measured in different tissues (liver, muscle, gills and digestive tract) of two W. Mediterranean mesopelagic (350–450 m) fish species; namely, the benthic Lepidorhombus boscii and the demersal Phycis blennoides. The accumulation was basically dependent on the tissue lipid contents, livers exhibiting the higher burdens, which nevertheless were one order of magnitude lower than those found in coastal fish from the same area. Significant differences were observed on the PCB patterns related to the different fish habitats. Thus, PCB levels were higher in gills and muscles of the benthic L. boscii, and both gills and digestive tract, as well as the muscle storage, were relatively enriched in highly chlorinated congeners. Among the different tissues, livers of both species were depleted in lower PCB congeners, and particularly in those containing meta and para vicinal H-atoms, which are more easily metabolized. In this respect, P. blennoides showed an apparently greater metabolic capacity than L. boscii. This is in agreement with the fact that P. blennoides showed higher hepatic cytochrome P450 content (1.6-fold) and substantially higher glutathione S-transferase activitiy (9-fold) than the flat fish.