EFFECT OF ALUMINUM AND LEAD ON ACTIVITY IN THE FRESH-WATER POND SNAIL LYMNAEA-STAGNALIS

Time-lapse video was used to examine the effect of short- (19 h) and long-term (1 year) exposure to Al or Pb at neutral pH in static water conditions on the total distance moved by the freshwater snail Lymnaea stagnalis. Aluminium at 100, 200, 500, or 1000 mu g . L(-1) normally depressed and Pb al 50 and 200 mu g . L(-1) often increased activity over the first 19 h of exposure. Smaller (younger) snails generally showed greater sensitivity to Al. Exposure to 100 or 500 mu g Al . L(-1) for up to 30 days caused hyperactivity, but thereafter and 1 year later, activity was similar to controls, suggesting that the snails had become tolerant. Lead (200 mu g . L(-1)) caused continued hyperactivity for up to 50 days, although movement was significantly reduced after 1 year, suggesting that acclimation had occurred. The effect of Al is interesting given the supposed limited bioavailability of this metal at neutral pH.