The effect of digenean (Platyhelminthes) infections on heavy metal concentrations in Littorina littorea

This study examined the inter-relationships between molluscs, heavy metal concentrations and trematode parasites. Littorina littorea (Mollusca: Gastropoda) were sampled seasonally from two sites in a tidal lagoon. Site A was close to the inflow of a polluted stream whilst site B was at the opposite end of the lagoon. The samples were analysed for lead, iron, copper and nickel. Metal concentrations in L. littorea varied with site, season and parasite infection, and exceeded comparative non-polluted concentrations for all metals in some samples. Parasitized periwinkles consistently had significantly lower levels of iron, copper and nickel than uninfected periwinkles.