Karlsson, J. J. Climate Impacts Research Centre, Jan.Karlsson@ans.kiruna.se
Andersson, A. J. Climate Impacts Research Centre, Agneta.nordstrom@umf.umu.se

Climate changes may affect lake ecosystems mainly via alteration in the export of dissolved organic carbon (DOC). DOC seems to play a key role in the structure and function of aquatic ecosystems, via regulation of the plankton food web. The aim of this project is to assess how different climatic variables affects the input of allochthonous DOC to lakes. Furthermore, to elucidate how different DOC concentrations in lakes affects the structure of the plankton communities and the relationship between primary production and heterotrophic bacterial production. Sixteen lakes located at different altitudes in the mountain areas in the north of Sweden are being sampled monthly. Preliminary data from the summer 1998 indicate large variations in the structure of plankton communities as well as in bacterial and primary production rates. Samples for stable isotopes (13C, 15N) have been taken to quantify the relative importance of different food sources in supporting higher trophic levels in the lakes. The field study has been complemented with a truncation experiment to study the structure of the microbial food web in an alpine clear water lake and a humic boreal lake.
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
Code: SS33TH0898S