CARBON AND OXYGEN-ISOTOPE VARIATIONS WITHIN THE SHELL OF AN AFRICAN LAND SNAIL (LIMICOLARIA KAMBEUL CHUDEAUI GERMANIN) - A HIGH-RESOLUTION RECORD OF CLIMATE SEASONALITY

Stable isotope analyses at high-resolution intervals along the growth axis of a shell of the land snail Limicolaria kambeul chudeaui Germain , collected in Ethiopia, show a cyclic pattern of delta(18)O variation . The cycles have regular periodicity but vary in amplitude. The shape and amplitude of the shell delta(18)O cycles is consistent with seaso nal changes in the amount and isotopic composition of the rainfall, co upled with temprraturc and evaporative effects. The number of cycles ( similar to 10) corresponds to the estimated lifespan of Limicolaria. G enerally constant delta(13)C values suggest unvarying diet, environmen tal CO2 influences, and metabolism throughout the snails life, except for one interval of large variations in both delta(13)C and delta(18)O that may be related to the onset of reproductive activity. If similar results can be obtained for fossil shells, they may provide a high-re solution record of past seasonal climate variability.