Continental palaeoclimate archives in subseasonal resolution remain limited in Europe, restricting insights into short-term environmental variability. This study investigates the freshwater gastropod Viviparus hellenicus as a potential high-resolution climate archive, using specimens from six habitats in Lake Trichonida, Greece, a large, deep lake in a semi-arid Mediterranean setting. Stable isotope patterns across shell ontogeny reveal sinusoidal δ18O patterns indicative of annual cycles, with minimal seasonal bias and strong correlation to water temperature. These trends suggest that evaporation exerts limited isotopic influence in well-buffered, deep limnic systems despite semi-arid climatic conditions. In contrast, shells from a nearby shallow, transitional site show greater sensitivity to shifting water sources and evaporative enrichment of the lake water, underscoring the role of local hydrology in shaping isotopic signals. While the shells reliably record seasonal interannual temperature variability, observed δ18O offsets and intraspecific variability complicate absolute temperature reconstructions. These uncertainties are likely to be amplified in fossil assemblages. Overall, Viviparus shells are considered promising high-resolution archives of continental climate, provided that local ecological and hydrological contexts are carefully considered.
