Environmental changes in an alpine lake (Gossenkollesee, Austria) over the last two centuries the influence of air temperature on biological parameters

Changes in microfossils (diatoms, chrysophytes, chironomids and cladocera remains), geochemistry and deposition of atmospheric pollutants have been investigated in the sediment records of the alpine lake Gossenkollesee ( Tyrol, Austria) spanning the last two centuries. The sediment records were compared with seasonal and annual air temperature trends calculated for the elevation (2417 m a. s. l.) and the geographical position (47degrees13'46"N, 11degrees00'51"E) of the lake, and with precipitation records available since 1866 from Innsbruck. Temperature trends followed a 20 30 year oscillation between cold and warm periods. Regarding long-term changes, temperature trends showed a U-shaped trend between 1780 and 1950, followed by a steep increase since 1975.