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University of Helsinki Faculty of XXX

Environmental Change Research Unit - ECRU


Tracking carbon dynamic patterns and climate forcing through post-glacial mire development history by combining modern flux measurements and palaeoecological information
Impacts of climate change on Arctic environment, ecosystem services and society (CLICHE)
Biomarkers – a new potential method to study highly humified peat components
Past water table fluctuations and related changes in carbon accumulation rates in mires – a quantitative multi proxy-based reconstruction from different climate regimes
Impacts of multiple environmental stressors on subarctic lake food web dynamics (MESS)
Climate variability in NW Europe during the past 4000 years and its ecological consequences (CLIM-ECO)
Science workshop on past, present and fututure climate change
Long-term changes in lake ice conditions in northern Finland
Responses of Boreal ecosystem carbon exchange to changing environment in different spatio-temporal scales
Former Projects

Contact information:

Environmental Change Research Unit (ECRU)
Department of Environmental Sciences
P.O. Box 65 (Viikinkaari 1)
FIN-00014 University of Helsinki

Phone: +358-9-1911
(main switch board)
or see People


Jan Weckström



Värriö research station, photo: Jan Weckström


Founded by: Maj and Tor Nessling Foundation, Ella and Georg Ehrnrooth Foundation
Duration: 2010-2012

Värriö research station, photo: Jan WeckströmSubarctic aquatic ecosystems confront multiple environmental variables related to catchment, climate and human act. In this project we use neo- and palaeolimnological approaches to study the natural and human-induced sudden mode shifts and ecological reorganisations in subarctic aquatic ecosystems. One of the unpleasant changes is appearance of nuisance blue-green algae blooms in to the lake. These cyanobacterial blooms are common problems of eutrophic lakes, but they occur in oligotrophic lakes relatively rarely. However, recently cyanobacterial blooms have been observed also in oligotrophic high altitude lakes. The aim of this project is to clarify the impacts of multiple environmental stressors on origin of cyanobacterial blooms in subarctic lakes.

Cyanobacterial blooms in Lake Kuutsjärvi, photo: Teuvo HietajärviIn addition to catchment related variables, air-borne depositions of especially nitrogen have a clear impact on lakes. Reduced air-born nitrogen deposition can switch subarctic oligotrophic lakes from phosphorus limited to nitrogen limited ecosystems, which in turn favours nitrogen-fixing cyanobacteria over other algal groups. Another important factor strongly affecting the lake food web dynamics is the introduction of fish into the former fishless lake. As fish tend to prey on larger zooplankton, the size spectrum of zooplankton will be narrowed. Large zooplankton, especially cladocerans are more effective filtering in phytoplankton than small-sized cladocerans, and thus in fishless lakes zooplankton community could control algae blooms, while in rich-in-fish lakes it commonly fails.

Location of Lake KuutsjärviOur study area is Lake Kuutsjärvi (with a nearby fishless reference lake), which is located in northeastern subarctic Finland inside the Värriö Strict Nature reserve in the vicinity of the Värriö Research Station. Lake Kuutsjärvi provides a unique opportunity to study the impacts of multiple environmental variables on subarctic aquatic ecosystems as it is a “natural laboratory” because of the known date of fish introduction in 1970s and the possibility to remove the fish during this project.



Anne Liljendahl - PI

Marco Milardi

Susanna Siitonen

Petra Tallberg

Jan Weckström - PI

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