Authors: Fahy, Julie; Demierre, Eliane;Piaudel, Axelle;Oertli, Beat;

As climate change increasingly threatens biodiversity, we need to monitor closely the ecosystems at risk. Alpine waterbodies are particularly vulnerable to changes in temperature and precipitation, and the rarefaction or extinction of boreo-alpine species is expected.
Located at high altitudes (>2600 m a.s.l.) in the Swiss national park, the pondscape of Macun is relatively well protected from most anthropogenic pressures and represents an ideal setting to study the effects of climate change on alpine pond biodiversity. Given their potential as sentinels of global environmental change, the ponds of Macun have been regularly monitored since 2002, with aquatic macroinvertebrate sampling and physico-chemical measurements.
Our investigations evidenced that the macroinvertebrate diversity has remained quantitatively stable between 2002 and 2021, with no significant trend regarding species richness (p>0.05). Community composition has slightly changed (p<0.05), but with no expected decline in boreo-alpine taxa.
Long-term water temperature data (2005-2021) were investigated and do not show a perceivable trend towards warming, contrarily to the global pattern described for the same period in the Alps.
In conclusion, our current data do not yet reveal impacts of climate change on the biodiversity of Macun’s pondscape. It remains therefore crucial to continue to monitor these sensitive and preserved ecosystems.