UPTAKE AND FATE OF LEAD IN THE COMMON ASTEROID ASTERIAS-RUBENS (ECHINODERMATA)

Lead uptake kinetics in the body compartments of Asterias rubens indiv iduals exposed through sea water to different concentrations (5, 20, 5 0 mu g Pb l(-1)) were studied during 30 days. Uptake kinetics were alw ays best described by linear regressions. In every compartment, uptake rate increased significantly with the contaminating concentration. At a given concentration, the uptake rate of the central digestive tract was always significantly higher than that of the other compartments. After short-term exposures (50 mu g Pb l(-1), 8 days), fate of accumul ated Pb was followed in asteroids kept in non-contaminated water durin g 20 days. The central digestive tract and the pyloric caeca lost Pb a ccording to an inverse exponential trend and concentrations returned t o initial values after 4 to 8 days. Pb concentrations in the body wall decreased linearly. Pb concentrations in the skeleton did not vary si gnificantly. In the gonads, Pb concentrations kept on rising while exo genous Pb was no more supplied. Pb loss from the body wall and the dig estive compartments could account for such endogenous source to the go nads. It is suggested that Pb accumulated in the gonads is expulsed la ter through spawning. According to the parameters of uptake and loss k inetics, the central digestive tract and the skeleton are proposed as complementary temporal bioindicators of Pb contamination.