PIF2024 - High mountain lake biodiversity resilience to global change: a paleoecological approach for their future conservation (PID2023-149616OB-100)

The project proposes to study biodiversity resilience by tracking changes in lake community composition over the last ca. 2.000 years in four Pyrenean lakes with contrasting history of stressors pressure. We will focus on anthropogenic changes (non-native fish stocking, pasture-based livestock pressure and climate) and the type of biological responses that these changes have induced: gradual or abrupt. We will combine multivariate ordination techniques with nonlinear time-series methods (hierarchical generalized additive models) to characterize trajectories of community responses in each lake, and coherence in such trajectories across lakes. The project will use a space for time approach with regional information of a total of 78 lakes combined with sedaDNA and traditional paleolimnological proxies analysed in the sediment records. The relative importance of the three stressors on high mountain lakes has not been studied in detail. Previous results from our group have shown that fish can have a strong impact on biodiversity, which is higher when minnows have been introduced. We have also shown that it is possible to restore lakes by removing non-native fish. However, it is crucial to know when native biodiversity is fully recovered, and what is the influence of the other stressors on the recovery once fish are eradicated.