SS3.09 Climate-Lake Interactions
Date: Wednesday, June 12, 2002
Time: 3:00:00 PM
Location: Colwood
 
Sorvari, S, , Dept. of Ecology & Systematics, University of Helsinki, Helsinki, Finland, sanna.sorvari@helsinki.fi
KorholaA, Dept. of Ecology & Systematics, University of Helsinki, Helsinki, Finland, atte.korhola@helsinki.fi
Thompson, R, , Dept. of Geology & Geophysics, The University of Edinburgh , Helsinki, United Kingdom, roy@ed.ac.uk
 
AQUATIC ECOSYSTEM RESPONSE TO RECENT ARCTIC WARMING IN FINNISH LAPLAND
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High-resolution palaeolimnological data from a number of remote and non-polluted lakes in Finnish Lapland reveal a distinct change in diatom assemblages that parallels the post-19th century Arctic warming detected by examination of long-term instrumental series, historical records of ice cover and tree-ring measurements. The change was predominantly from benthos to plankton and affected the overall diatom species richness. In a canonical ordination, particularly strong relationship was found between spring temperatures and compositional structure of diatoms. The change is reflected additionally by other biological indicators, suggesting that entire lake ecosystems have been affected. The mechanism behind the biological response is unclear, but it may be related to decreased ice-cover duration, prolonged growing season and increased thermal stability. Credence to our interpretation is achieved from studies on present-day limnology in one of the study sites that demonstrate close relationships between temperature, thermal structure and biological processes. We postulate that 19th century Arctic warming, rather than acidic or other anthropogenic deposition, is responsible for the recent ecological changes in these high latitude lakes.