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Abstract

Sediment cores spanning the last two centuries were taken in Hagelseewli, a high-elevation lake in the Swiss Alps. Contiguous 0.5 cm samples were analysed for biological remains, including diatoms, chironomids, cladocera, chrysophyte cysts, and fossil pigments. In addition, sedimentological and geochemical variables such as loss-onignition, total carbon, nitrogen, sulphur, grain-size and magnetic mineralogy were determined. The results of these analyses were compared to a long instrumental air temperature record that was adapted to the elevation of Hagelseewli by applying mean monthly lapse rates.During much of the time, the lake is in the shadow of a high cliff to the south, so that the lake is ice-covered during much of the year and thus decoupled from climatic forcing. Lake biology is therefore influenced more by the duration of ice-cover than by direct temperature effects during the short open-water season. Long periods of ice-cover result in anoxic water conditions and dissolution of authigenic calcites, leading to carbonate-free sediments.The diversity of chironomid and cladoceran assemblages is extremely low, whereas that of diatom and chrysophyte cyst assemblages is much higher. Weak correlations were observed between the diatom and chrysophyte cyst assemblages on the one hand and summer or autumn air temperatures on the other, but the proportion of variance explained is low, so that air temperature alone cannot account for the degree of variation observed in the palaeolimnological record.Analyses of mineral magnetic parameters, spheroidal carbonaceous particles and lead suggest that atmospheric pollution has had a significant effect on the sediments of Hagelseewli, but little effect on the water quality as reflected in the lake biota. This is the eighth of 11 papers published in this special issue on the palaeolimnology of remote mountain lakes in Europe resulting from the MOLAR project funded by the European Union. The guest editor was Richard W. Battarbee.

Composition of highly diverse diatom community shifts as response to climate change: A down-core study of 23 central European mountain lakes

“…The subfossil diatom assemblages of type 3 lakes were characterized by undirected shifts particularly within the small fragilarioid species. In contrast, type 4 lakes showed a general decrease of species of the Staurosira -complex, which can be interpreted as response to a warming environment (Lotter et al, 1999(Lotter et al, -2002. They were replaced by Achnanthidium spp.…”

“…In contrast, type 2 lakes are characterized by a sudden appearance of planktic species within the last ~30 years, accompanied by a decrease of Staurosira species as a response to climate change (Lotter et al, 1999(Lotter et al, -2002Rühland et al, 2015). Type 2 lakes are four to ten meters deep or even deeper in case of cooler alpine lakes.…”

“…In limnological research, all the factors described above that cause the complex impact of climate change in the Alps have so far and to the best of our knowledge only been studied in high alpine lakes with crystalline bedrock in the catchmentse.g. Lake Gössenköllensee, Austria (Koinig et al, 2002;Kamenik et al, 2000) or Hagelseewli, CH (Lotter et al, -2002Lotter and Bigler, 2000) or at large prealpine lakes such as Lake Mondsee (Namiotko et al, 2015). However, effects of climate change on biological communities in mountain lakes from calcareous areas are poorly investigated, even though they comprise the majority of lakes in areas such as the Bavarian Alps.…”

Triple-isotope analysis in tree-ring cellulose suggests only moderate effects of tree species mixture on the climate sensitivity of silver fir and Douglas-fir

“…1 , Table S2 available as Supplementary data at Tree Physiology Online). Temperature values were corrected for the differences in elevation between the sites and the meteorological stations with published monthly temperature lapse rates from Lotter et al. (2002) .…”

Evolution of lake surface temperatures of high-altitude lakes in the European Alpine region under climate change

“…Topographic shading was the main reason for lake Haegelseewli (2339 m a.s.l.) to decouple from climate forcing, i.e., ice cover formation during large parts of the year minimized direct temperature effects during the short open water season (Lotter et al, 2002). Either relatively warm or undercooled lakes located at the same altitude are the result of distinct responses to a common driver.…”