Trace metals in the common mussel, Mytilus edulis (L.), and in the alga Fucus vesiculosus (L.) from the region of the sound (Öresund)

Abstract

Concentrations of zinc, cadmium, lead and iron were determined in whole soft parts of mussels, Mytilus edulis (L.), and in growing tips of the alga Fucus vesiculosus (L.) from a total of 20 locations in the area of the Sound between Sweden and Denmark. Pollution profiles produced for each metal were similar in any one of the species studied but the profiles for metals in M. edulis were distinct from those for metals in F. vesiculosus. Results for mussels agreed broadly with those reported previously for this region, indicating a northward decrease in available metal concentrations. By contrast, results for algae showed few differences in metal availability throughout the study area, although some local effects were evident. The differences in the pollution profiles exhibited by these two organisms depend on their response to different portions of the total trace metal load of ambient waters. Results from the alga agree well with available data on the concentrations of trace metals in solution in waters of the Sound. The alga thus appears to be responding only to metals in solution, as suggested by previous authors. By contrast, the major proportion of the total body load of metals in mussels is derived from ingested phytoplankton. The pollution profiles exhibited by mussels may be explained if phytoplankton from the Baltic Sea contain higher concentrations of trace metals than do those from Kattegat. Possible mechanisms for the production of such differences in the metal contents of the two phytoplankton populations, and the ecological implications of these differences, are briefly discussed.