Lake Tovel: long-term stable isotope (δ18O) study

Climate change is already having significant effects on aquatic ecosystems with recent scenarios indicating greater change in the Alps. Projected climate change models are predicting drastic changes in precipitation patterns, with mid-altitude lakes particularly vulnerable. These lakes provide valuable ecosystem services such as irrigation, power, recreation and fishing. LTER research site Lake Tovel, Italy (46.26137 N, 10.94934 E) is a small, Alpine lake located at 1178 m asl. The oligotrophic lake, divided into a shallow (4 m) and a deep basin (39 m), is fed by groundwater, upwelling in the littoral zone of the shallow basin. Stable isotopes of oxygen (δ18O) have been sampled monthly along a depth gradient in both basins. The dataset covers the years 2002-2003 and is ongoing from 2009. δ18O can be used to successfully investigate many aspects of lake hydrology; for example Lake Tovel δ18O values between -13 and -12 ‰ indicate that groundwater originates at ca. 1000 m above the lake. Stable isotopes offer a finer resolution with respect to temperature in monitoring aspects such as origin of water, evaporation, mixing and their long-term monitoring. This finer resolution can provide a better understanding of a changing hydroclimate and act as an ‘early warning’ system, making timely mitigation actions possible.