ENVIRONMENTAL HISTORY AS REFLECTED BY FRESH-WATER PEARL MUSSELS IN THE RIVER VRAMSAN, SOUTHERN SWEDEN

The distribution of elements in shells of the freshwater pearl mussel, Margaritifera margaritifera, from the River Vramsan, southern Sweden, was analyzed with high temporal resolution with the nuclear microscop e SLIM-UP. The results show: (i) annual variations of strontium and ma nganese. The variation of Sr is anticorrelated to that of Mn with high Sr concentration on the winter lines, and high Mn in the summer. The high Mn concentration in the summer correlates to a depletion in oxyge n in the surrounding water; (ii) high Sr concentrations on growth dist urbance lines; (iii) an ontogenetical variation of Sr with high concen trations in younger stages (before sexual maturation); and (iv) a long -term decrease of manganese in the shells. The long-term decrease of M n is also consistent with results from Neutron Activation Analysis.