ACCUMULATION, DEPURATION AND GROWTH EFFECTS OF TRIBUTYLTIN IN THE FRESH-WATER BIVALVE DREISSENA-POLYMORPHA UNDER FIELD CONDITIONS

The uptake of tributyltin (TBT) in caged Dreissena polymorpha was inve stigated in a freshwater marina contaminated with TBT released from an tifouling paints. Depuration was followed on bivalves transferred from the marina, live naturally, to a location without organotin contamina tion. The butyltin concentration of the mussel tissues and the water w as determined and the growth of the mollusks followed during 105 d. Th e accumulation was extremely rapid, reaching a threshold of 63 mug/g d ry weight after 35 d with a very high BCF of 900,000. No effect on gro wth or mortality was observed. The elimination experiment showed a hal f-life of 26 d without reaching a steady state after 105 d. The mean a mbient TBT water concentrations were 70 and 4 ng/L during the uptake a nd depuration experiments, respectively. Rate constants have been calc ulated. The growth rate of the eliminating Dreissena polymorpha was ha lf as high as the rate of the accumulating mussels and of those caged in the site with low TBT concentrations serving as reference. The biva lves living naturally in the marina might have been affected during th eir larval or juvenile stages, resulting in a reduced growth rate of t he adults, which remained diminished even when transferred to an area remote from known TBT sources.