Metallothionein and Glutathione as Stress Indicators in Bivalves in the Lagoon of Venice
Bivalves are often used as indicators of metal pollution, as their digestive glands and gills are important target organs for metal accumulation. With the aim of studying the effects of stress conditions (heavy metal pollution) using metallothionein (MT) and glutathione (GSH) as markers, we studied three species of Bivalvia: Mytilus galloprovincialis, which feeds on suspended matter filtered from sea water by cilia on the gill surfaces, and Tapes philippinarum and Scapharca inequivalvis, which live on sediments. These species were sampled in spring 1998 in two stations with different pollution levels, at Chioggia and Marghera in the Lagoon of Venice. Digestive gland MT contents were significantly different in the same station in the three species: the specimens with the greatest MT contents were T. philippinarum. The same species at Marghera was also the one with the greatest amounts of Mn, Co and Fe in the digestive gland. GSH digestive gland contents and Mn, Co and Fe concentrations were statistically greater in M. galloprovincialis from Chioggia with respect to M. galloprovincialis from Marghera. GSH digestive gland contents of S. inequivalvis were also higher in the species from Chioggia. Comparing digestive gland results of the three species at the same two stations, M. galloprovincialis and S. inequivalvis had significantly greater amounts of GSH than T. philippinarum. As regards gills, M. galloprovincialis from Chioggia had significantly greater amounts of GSH than M. galloprovincialis from Marghera; in the latter station S. inequivalvis had significantly greater amounts of GSH and metals than M. galloprovincialis. We also looked for relationships between different parameters: length or weight with MT or GSH.
KeywordsHeavy Metal Pollution Digestive Gland Macoma Balthica Gill Surface Tissue Metal Concentration
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