| Abstract | 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 Gossenköllesee (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 (47°13?46??N, 11°00?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.
Physical, geochemical, and organic parameters were not controlled by air temperature. Among the biological records only diatoms and chrysophytes reacted to air temperature changes: the relative abundance of planktonic diatoms increased during warm periods and changes in mean annual alpine air temperature explained 36.5% of their variation. The relation between abundance of seasonal stomatocyst types and air temperature varied on two
different time scales: while summer stomatocysts were influenced by short term temperature fluctuations, the autumn stomatocysts were affected only by the long term changes. Other biological parameters exhibited a constant species composition (chironomids, pigments) or changes were small and independent of temperature (cladocera).
Spheroidal carbonaceous fly-ash particles, and trends in Pb and Cr indicated increasing deposition of atmospheric pollutants but had no detectable effects on the biological parameters either. In respect to temperature variations over the last 200 years, this alpine lake is much less sensitive than expected and has thus to be regarded as a well buffered site. However, temperature alone is not sufficient to understand changes in species composition and other biogeochemical processes with unknown historical patterns might have affected species composition more strongly. |
| Authors | Koinig K.A., Kamenik C., Schmidt R., Agustm-Panareda A., Appleby P., Lami A., Prazakova M., Rose N., Schnell X.A., Tessadri R., Thompson R., Psenner R. |
| Text | 52731 2002 climate change palaeolimnology lake sediments diatoms chrysophytes chironomids cladocera pigments Environmental changes in an alpine lake Gossenkollesee, Austria over the last two centuries the influence of air temperature on biological parameters Koinig K.A., Kamenik C., Schmidt R., Agustm Panareda A., Appleby P., Lami A., Prazakova M., Rose N., Schnell X.A., Tessadri R., Thompson R., Psenner R. Karin A. Koinig Institute of Zoology and Limnology, University of Innsbruck, Austria Christian Kamenik Austrian Academy of Science, Institute of Limnology, Mondsee, Austria Roland Schmidt Austrian Academy of Science, Institute of Limnology, Mondsee, Austria Anna Agusti Panareda Department of Geology and Geophysics, University of Edinburgh, Scotland, UK Peter Appleby Department of Mathematical Sciences, University of Liverpool, UK Andrea Lami CNR Istituto Italiano di Idrobiologia, Verbania Pallanza, Italy Miroslava Prazakova Department of Hydrobiology, Charles University, Prague, Czech Republic Neil Rose Environmental Change Research Centre, University College London, UK Øyvind A. Schnell Department of Zoology, University of Bergen, Norway Richard Tessadri Institute of Mineralogy and Petrography, University of Innsbruck, Austria Roy Thompson Department of Geology and Geophysics, University of Edinburgh, Scotland, UK Roland Psenner Institute of Zoology and Limnology, University of Innsbruck, Austria 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 47°13 46 N, 11°00 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. Physical, geochemical, and organic parameters were not controlled by air temperature. Among the biological records only diatoms and chrysophytes reacted to air temperature changes the relative abundance of planktonic diatoms increased during warm periods and changes in mean annual alpine air temperature explained 36.5% of their variation. The relation between abundance of seasonal stomatocyst types and air temperature varied on two different time scales while summer stomatocysts were influenced by short term temperature fluctuations, the autumn stomatocysts were affected only by the long term changes. Other biological parameters exhibited a constant species composition chironomids, pigments or changes were small and independent of temperature cladocera . Spheroidal carbonaceous fly ash particles, and trends in Pb and Cr indicated increasing deposition of atmospheric pollutants but had no detectable effects on the biological parameters either. In respect to temperature variations over the last 200 years, this alpine lake is much less sensitive than expected and has thus to be regarded as a well buffered site. However, temperature alone is not sufficient to understand changes in species composition and other biogeochemical processes with unknown historical patterns might have affected species composition more strongly. 28 Published version Journal of Paleolimnology 28 147 160 Journal_of_Paleolimnology_28_147_160.pdf Articolo in rivista Kluwer Academic 0921 2728 Journal of paleolimnology Journal of paleolimnology J. paleolimnol. andrea.lami LAMI ANDREA |
