A comparative study of lead uptake by three populations of the snail Helix aspersa Muller

Pb uptake by three populations of the snail Helix aspersa was measured in a series of experiments supplying PbS04 in an agar diet. Uptake rates in snails from a site grossly polluted with Pb were lower than in the two other populations and were unafected by the initial body burdens of Pb. Populations of snails from a Pb-free site showed much greater variability in tissue Pb burdens and faster rates of accumulation than populations from the polluted site. Snails from a site with Pb concentrations between the other two sites showed intermediate rates of uptake. It is suggested that snails from the highly contaminated site have adapted to high environmental levels of Pb and that this adaptation is genetically based.