| Title | A multi proxy analysis of climate impacts on the recent development of subarctic lake Saanajdrvi in Finnish Lapland |
| Abstract | Responses to recent climatic changes in the sediment of subarctic Lake Saanajärvi in northwestern Finnish Lapland are studied by comparison of various biological and sedimentological proxies with the 200-year long climate record, specifically reconstructed for the site using a data-set of European-wide meteorological data. The multi-proxy evidence of simultaneously changing diatom, Cladocera, and chrysophyte assemblages along with the increased rates of organic matter accumulation and pigment concentrations suggest that the lake has undergone a distinct typological change starting from the turn of the 20th century. This change, indicating an increase in lake productivity, parallels a pronounced rise in the meteorologically reconstructed mean annual and summer temperatures in the region between ca. 1850 and 1930's. We postulate that, during the Little Ice Age, the lake was not, or was only weakly, thermally stratified during summer, whereas the subsequent increase in air and hence epilimnetic water temperatures resulted in the development of the present summer stratification. The increased thermal stability of the lake created more suitable conditions for the growth of phyto- and zooplankton and changed the overall primary production from benthos to plankton. Mineral magnetic and carbonaceous particle records suggest long-distance pollution, particularly since the 1920's, yet the observed changes in lake biota and productivity can hardly be explained by this very minor background pollution; the 20th century species configurations are typical of neutral waters and do not indicate any response to pollution. |
| Source | Journal of paleolimnology 28 (1), pp. 59–77 |
| Keywords | Finnish LaplandSubarctic lakeClimate changeLake sedimentsDiatomsCladoceraChrysophytesMagnetismCarbonaceous particlesPlant pigments |
| Journal | Journal of paleolimnology |
| Editor | Kluwer Academic, Boston, Paesi Bassi |
| Year | 2002 |
| Type | Articolo in rivista |
| DOI | 10.1023/A:1020371902214 |
| Authors | Korhola A., Sorvari S., Rautio M., Appleby P.G., Dearing J.A., Hu Y., Rose N., Lami A., Cameron N.G. |
| Text | 52725 2002 10.1023/A 1020371902214 Finnish Lapland Subarctic lake Climate change Lake sediments Diatoms Cladocera Chrysophytes Magnetism Carbonaceous particles Plant pigments A multi proxy analysis of climate impacts on the recent development of subarctic lake Saanajdrvi in Finnish Lapland Korhola A., Sorvari S., Rautio M., Appleby P.G., Dearing J.A., Hu Y., Rose N., Lami A., Cameron N.G. A. Korhola Division of Hydrobiology, Department of Ecology and Systematics, University of Helsinki, Finland S. Sorvari Division of Hydrobiology, Department of Ecology and Systematics, University of Helsinki, Finland M. Rautio Division of Hydrobiology, Department of Ecology and Systematics, University of Helsinki, Finland P.G. Appleby Department of Mathematical Sciences, University of Liverpool J.A. Dearing Environmental Magnetism Laboratory, University of Liverpool Y. Hu Environmental Magnetism Laboratory, University of Liverpool N. Rose Environmental Change Research Centre, University College London A. Lami CNR Ist.Ital.Idrobiol. Verbania Pallanza N.G. Cameron Environmental Change Research Centre, University College London Responses to recent climatic changes in the sediment of subarctic Lake Saanajarvi in northwestern Finnish Lapland are studied by comparison of various biological and sedimentological proxies with the 200 year long climate record, specifically reconstructed for the site using a data set of European wide meteorological data. The multi proxy evidence of simultaneously changing diatom, Cladocera, and chrysophyte assemblages along with the increased rates of organic matter accumulation and pigment concentrations suggest that the lake has undergone a distinct typological change starting from the turn of the 20th century. This change, indicating an increase in lake productivity, parallels a pronounced rise in the meteorologically reconstructed mean annual and summer temperatures in the region between ca. 1850 and 1930 s. We postulate that, during the Little Ice Age, the lake was not, or was only weakly, thermally stratified during summer, whereas the subsequent increase in air and hence epilimnetic water temperatures resulted in the development of the present summer stratification. The increased thermal stability of the lake created more suitable conditions for the growth of phyto and zooplankton and changed the overall primary production from benthos to plankton. Mineral magnetic and carbonaceous particle records suggest long distance pollution, particularly since the 1920 s, yet the observed changes in lake biota and productivity can hardly be explained by this very minor background pollution; the 20th century species configurations are typical of neutral waters and do not indicate any response to pollution. 28 Published version Journal of Paleolimnology 28 59 77 Journal_of_Paleolimnology_28_59_77.pdf Articolo in rivista Kluwer Academic 0921 2728 Journal of paleolimnology Journal of paleolimnology J. paleolimnol. andrea.lami LAMI ANDREA TA.P02.005.002 Uso della paleolimnologia come strumento per lo studio del paleoclima e dell evoluzione climatica |
