Effects of season and species on physiological condition and contaminant burdens in mussels (Mytilus edulis L. and Mytilus trossulus G.): Implications for mussel watch programs.

摘要

The "Mussel Watch" is a coastal biomonitoring program, which involves the collection and chemical analysis of mussels as an alternative to sea water and sediment analysis. Mussel watch programs have been conducted throughout the world for a number of years, and researchers have identified a number of environmental and biological variables which may influence contaminant concentrations in mussels. This study addressed two important variables that should be considered in any mussel watch program, season and species.;Two species of mussels, Mytilus edulis and Mytilus trossulus, were collected monthly for one year from Digby, Nova Scotia, on the Annapolis Basin, Bay of Fundy. Condition index (CI) and gonad index (GI) determinations were conducted monthly for individual mussels, and composite mussel tissue samples were analyzed at four times during the year for metals (copper, nickel, cadmium, iron, aluminum, silver, lead, chromium, zinc and mercury) and organic chemicals (PAHs, PCBs and pesticides).;Seasonal profiles for CI and GI were influenced by seasonal temperatures, food availability and reproductive condition. Four different seasonal patterns were observed for metal burdens in M. edulis, while M. trossulus displayed six distinct seasonal patterns for metals. A consistent seasonal pattern was observed for all organic chemicals. No significant correlations between contaminant concentrations or burdens and CI, GI or lipid content were identified. Species differences were observed in terms of tissue weights, CI, GI, spawning times, chemical concentrations and seasonal patterns of accumulation of certain metals.;This study has shown that accurate species identification of the mussels used in mussel watch programs, as well as determination of suitable seasons for their collection and analysis, are necessary to avoid misinterpretation of data from such programs.