Effects of climate change on zooplankton community structure of the Middle Daugava over the last 50 years

In the spring, summer and autumn of 2008, samples of zooplankton were collected on the river Daugava in a stretch from Surozha in Belorussia to Dunava in Latvia, in 21 places on the right and left banks of the river, as well as in the middle of the river. The APHA 10200 methods was used for quality and quantity analyses of zooplankton. The results were compared to the results of the studies carried out by R.Škute in 1962-1966 and N.Sloka in 1956 in similar stretch of the river. The total number of zooplankton taxons in 2005-2008 has decreased by 38 taxons comparing to the number of taxons in 1956-1963. There are relevant changes in the structure of the taxons too. Such changes could be attributed to the long-term changes in climate and hydrology of the Daugava's drainage basin.