Monitoring of Hepatic Metallothionein mRNA Levels in the Fish Lithognathus mormyrus – Evaluation of Transition Metal Pollution in a Mediterranean Coast

The hepatic level of metallothionein (MT) mRNA in the sparid fish Lithognathus mormyrus, was used as bioindicator for detecting transition metals pollution in Mediterranean marine habitats. Hepatic MT mRNA levels in feral fish, sampled from different contaminated Haifa Bay locations were compared to in vivo laboratory studies using cadmium as a representative contaminant. In the laboratory, dose response experimental results (27°C), were compared with the results of a similar experiment (21°C; Tom et al., 1998). Temperature significantly influenced MT mRNA induction in livers of L. mormyrus. Hepatic cadmium levels were measured during the 21°C induction and the degradation experiments and their effect on MT mRNA degradation is discussed. In the field study, hepatic MT mRNA levels were high in the fish sampled near polluted areas and lower in less polluted sites. These results indicate the sensitivity of fish MT mRNA to transition metal fluctuations in the field.