Alpine lakes are remote and pristine ecosystems, hosting communities shaped by severe environmental conditions and showing simple structures, low diversity and simplified trophic webs. Paleolimnological analyses of subfossil communities are commonly used to reconstruct past environmental changes, especially in relation to impacts due to human activities. The effects of flood events in mountains are of particular interest: due global warming, the increase in frequency of extreme precipitations has been observed also in the European Alps, but interpretation and understanding of these events are often difficult in mountain areas, due to their complex topography. In the present study, we carried out paleolimnological analyses in two alpine lakes in Western Alps (Balma Lakes, Piedmont, Italy), with the aim to investigate temporal changes in subfossil assemblages, in relation to flood events due to the variation of precipitation regimes. The lakes are placed in the same geographical area, but they differ in shape, altitude, and morphological characteristics of the catchments. We analyze chironomid assemblages, commonly studied in paleolimnological reconstructions, and testate amoebae communities, which are still poorly studied in alpine lakes. Chemical characterizations of core profiles were also performed. Our results highlighted significant changes in the analyzed communities and allowed to identify different time periods related to variations in pluvial/drought events of the last 2000 years. Despite they are placed in the same area, the analyzed lakes showed a different history, due to morphological differences in basin morphology. Moreover, the effect due to fish introduction was analyzed, representing a possible bias in environmental evaluations of paleolimnological datasets. Historical and natural archives provided by lacustrine sediments represent an interesting sources of information to better understand past and future evolution of flood and precipitation events and their effects on communities of alpine lakes, which are ”early warning systems” for the main mountain area.
Paleolimnological analyses in the Balma Lakes (Northwestern Italy): classic and new proxies to understand changes in flood regimes in alpine ecosystems
Bertoli M.;Salvi G.;Pizzul E.
2023-01-01
Abstract
Alpine lakes are remote and pristine ecosystems, hosting communities shaped by severe environmental conditions and showing simple structures, low diversity and simplified trophic webs. Paleolimnological analyses of subfossil communities are commonly used to reconstruct past environmental changes, especially in relation to impacts due to human activities. The effects of flood events in mountains are of particular interest: due global warming, the increase in frequency of extreme precipitations has been observed also in the European Alps, but interpretation and understanding of these events are often difficult in mountain areas, due to their complex topography. In the present study, we carried out paleolimnological analyses in two alpine lakes in Western Alps (Balma Lakes, Piedmont, Italy), with the aim to investigate temporal changes in subfossil assemblages, in relation to flood events due to the variation of precipitation regimes. The lakes are placed in the same geographical area, but they differ in shape, altitude, and morphological characteristics of the catchments. We analyze chironomid assemblages, commonly studied in paleolimnological reconstructions, and testate amoebae communities, which are still poorly studied in alpine lakes. Chemical characterizations of core profiles were also performed. Our results highlighted significant changes in the analyzed communities and allowed to identify different time periods related to variations in pluvial/drought events of the last 2000 years. Despite they are placed in the same area, the analyzed lakes showed a different history, due to morphological differences in basin morphology. Moreover, the effect due to fish introduction was analyzed, representing a possible bias in environmental evaluations of paleolimnological datasets. Historical and natural archives provided by lacustrine sediments represent an interesting sources of information to better understand past and future evolution of flood and precipitation events and their effects on communities of alpine lakes, which are ”early warning systems” for the main mountain area.Pubblicazioni consigliate
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