Abstract
The oxygen and carbon stable-isotope ratios from fossil snail shells within a small intramontane lake in southwest Turkey are used to highlight the potential, and problems, of using freshwater snail carbonate as a palaeoenvironmental proxy. Two species (Gyraulus piscinarum and Valvata cristata) yielded different isotope ratios at the same sampling intervals, probably due to differences in water-isotope composition between different microhabitats. Isotope ratios from a number of individual shells from the same sampling intervals (representing 7–25 years), show large ranges (up to 8‰ for 18O) for each species. Only by analysis of a significant number of species-specific shells (5) from each sampling interval can a true understanding of environmental change be obtained. Averages of the data provide an insight into longer-term climatic variation while the ranges provide an estimate of short-term (decadal) environmental variability.
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