LEVELS OF TRACE-METALS AND EFFECT OF BODY-SIZE ON METAL CONTENT AND CONCENTRATION IN ARCTICA-ISLANDICA L (MOLLUSCA, BIVALVIA) FROM KIEL BAY, WESTERN BALTIC

The levels of four trace metals (Cd, Cu, Pb, and Zn) in the whole soft body and in different organs of the ocean quahog Arctica islandica we re evaluated from four stations in Kiel Bay, Western Baltic. The relat ionships between the contents and concentrations of these metals and b ody size (weight and length) were also investigated. Double logarithmi c plots of metal contents and concentrations against dry body weight a nd shell length, respectively, show straight-line relationships. The r esults indicate that smaller individuals have higher concentrations of Cu and Zn, two essential metals, while larger individuals have higher concentrations of Cd and Pb, two non-essential metals. The calculated regression slopes of metal content against dry-body weight revealed t hat Cd and Cu appear to be affected by maturation since two different slopes are observed for both metals before and after maturation. This was not obvious for Pb and Zn. Pooled slopes of metal content against dry-body weight for all animal sizes indicated that Cu and Zn have a o ne common slope of (0.82) and Cd and Pb another common one of (1.51). Plots of metal concentrations against shell length indicated also that Cu and Zn have one common slope of (-0.54) and Cd and Pb another one of (1.56). Moreover, it was possible to calculate one final slope of ( 1.53) for Cd and Pb from both content/weight and concentration/length plots. This indicates that A. islandica may have one metabolic strateg y for the essential metals and another for the non-essential metals.