Lake Caldonazzo, effects of re-oligotrophication and climate change on lake thermal structure, the past and the future

During recent decades, climate change and re-oligotrophication have been affecting many lakes. Lake restoration frequently involves smaller lakes (<10 km2) that are often overlooked in long-term limnological studies despite their importance for local stakeholders. In 2016, we published a study on the interplay between re-oligotrophication and climate change on the thermal structure of Lake Caldonazzo (Italy – southern Alps; area = 5.6 km2; maximum depth = 49 m) for the years 1973–2014. This study verifies predictions made with new data concerning the period 2014 – 2020. Even though new data were not taken at the same months than for the published study, predictions made were supported by new data. For example, hypolimnetic oxygen increase did not continue and showed a stagnant period after the year 2000, identifiable only with the longer dataset. Hypolimnetic cooling remained stable, beyond the year 2015. Even though predictions made were accurate, the continuous monitoring of Lake Caldonazzo, an important tourist attraction of the area, is necessary to detect any changes in the lake trophic state because of eutrophication-like effects of on-going climate change