Field application of autometallography and X-ray microanalysis using the digestive gland of the common mussel

The histological and ultrastructural localization of heavy metals in the digestive gland of the mussel, Mytilus galloprovincialis, was evaluated using autometallography and X-ray microanalysis on epoxy resin sections. Mussels were collected from two populations along Thermaikos gulf (port of Thessaloniki and Halastra) and one population in Strymonikos Gulf (Olympiada). With the use of autometallography, the light and electron microscopic observations indicated that in the digestive gland, the metals are localized in lysosomal structures, such as heterolysosomes and the residual bodies of digestive cells. Through both techniques, mussels collected from the port of Thessaloniki displayed concentrations of metals higher than those recorded in mussels from Halastra and Olympiada. This fact is consistent with other reports indicating a similar distribution of metals in Thermaikos Gulf and Strymonikos Gulf. The results of the study support the use of both techniques, autometallography and X-ray microanalysis, as a suite of stress indices for pollution biomonitoring studies.