The value of continuous monitoring programmes  

Climate impacts on freshwater systems can best be detected if long term data series are available. In Sweden the longest and most complete time series of freshwaters are available from the three largest lakes Vänern, Vättern and Mälaren. Here monthly monitoring during the ice-free season began in the late 1960s/early 1970s. Mostly sampling and analyses have been carried out by one and the same laboratory resulting in very homogenous time series. Such homogenous time series are rare in the world and therefore of very high value to get new insights into the effects of climate on freshwaters.

In the late 1980s additional national freshwater monitoring programmes were initiated, both in limed and in unlimed reference lakes. Here, 15 years of data are available to evaluate climate effects on freshwater ecosystems. All data can be downloaded at 

 Photo: Mats Gerentz

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