institute’s
lake
restoration programme
that Ventelä first recognised the effects of climate on water quality. “Although mainly due to human impact, we found that one of the really important background
issues for eutrophication
were climatic variations that had already happened,” explains Ventelä. With a holistic approach that combines long- term data from pre-existing monitoring programmes, paleolimnological studies and state-of-the-art wind and wave recording equipment, Ventelä hopes that by shedding light on the role of climate variation, efforts to restore water quality will be able to adapt to the changes that are happening now and changes that are yet to come. At lakes Pyhäjärvi in Finland and Taihu
in China, programmes monitoring their nutrient loads have been in place for decades. Functionally similar, the difference in trophic status between these shallow water systems is as distant as their geographical location. Doubling as a waste dumping ground, Taihu’s tourism, fishing and drinking services are repeatedly disrupted by recurring blooms of the toxic cyanobacteria Microcystis, most dramatically so in 2007 when two million inhabitants in the city of Wuxi
www.projectsmagazine.eu.com
were deprived of drinking water for an entire week. With decidedly less pressure from human and
activity an ongoing restoration
programme since 1995, Pyhäjärvi’s fortunes appear somewhat brighter, but
look at changes that have already occurred in its biological structure. Containing the remains of zooplankton and diatom communities, sediment cores offer insights into the stratification patterns of these organisms over the last 50 years which,
“Before, we were only able to estimate the role of wind and waves, but now we have got exact values which can be further used in models”
recent variations in the climate have begun to create new challenges for the lake’s restoration. Since 1962, the highest summer temperatures in the region have risen by an average of 0.9°C per decade with fluctuations in rainfall patterns playing havoc with the lake’s nutrient load. “Normally, the catchment in Pyhäjärvi
is frozen over the winter but
we’ve had late snow and now it’s melting,” states Ventelä in early spring. “It is certainly the wrong season for this kind of external load but it’s coming now.” To assess the lake’s response to climate variations in the past it is necessary to
combined with reconstructed densities of planktivorous fish, phosphorous levels and macrophyte coverage, begin to build up a picture of these structural developments. These comparisons have already begun
to implicate climatic stressors as a driving force behind the changes and with long- term ecological data at the project’s disposal, Ventelä can begin to peer into the futures of
the Pyhäjärvi and Taihu
lakes. Although extreme weather events are often a short lived blip in the long view, their effects linger. Trawling through the long time data series, spikes in weather behaviour that match predicted
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