An integrated chemical-biological study using caged mussels (Mytilus trossulus) along a pollution gradient in the Archipelago Sea (SW Finland, Baltic Sea).

Mussels (Mytilus trossulus) were caged along a known pollution gradient in the inner Archipelago Sea (northern Baltic Sea) and retrieved after 71 and 121 d for the measurement of selected chemical contaminants in tissues and biological endpoints including biochemical biomarkers and growth. Additional samples were collected during the growth season from a native mussel population at an alleged reference site. Elevated concentrations of numerous contaminants (e.g., PAH) were observed in spring, apparently due to the loss of tissue mass during the winter, while also the levels of many biomarkers (e.g., glutathione S-transferase activity) were elevated. Spatial and temporal changes in the accumulation of contaminants and biological parameters were observed with some of them (e.g., growth) linked to seasonal changes in environmental factors. The results underline the importance of understanding the effects of seasonal natural factors on the growth dynamics and general condition of mussels when assessing tissue concentrations of contaminants and biological effects.