Ecological characteristic of Vyžuona river

Work object – Vyžuona river, which has 26 km lenght, is left affluent of Šventoji river, belongs to subbasin of Šventoji river and runs from northeast to southwest of Lithuania. Work aim – identify water quality and bounded with it live organisms of Vyžuona river. Work tasks – analyse physical-chemical water parameters of Vyžuona river, identify varietal composition of organisms, define and evaluate contamination of river objects. Work results – After the reasearch was made there was defined that Vyžuona river in Utena town (1 km from Krašuona river and Vieša river junction) belongs to average contaminated rivers category measuring by parameters of water quality: common nitrogen quantity 1.9 times exceeds permissible quotas, 68.6 % of common nitrogen is composed of nitrate nitrogen, BDS7 quantity 2,7 times exceeds the LDK, concentration of phosphates 2.3 times exceeded permissible quotas. Krašuona river and Vieša river runs trough private houses section, which has no central sewer and that is the reason why mentioned rivers are bearing domestic contaminants into Vyžuona river. According to 2004-2006 data below the outlet from drain mechanism of UAB „Utenos vandenys“ refinement system there was found concentration of phosphorus which averagely 1,75 times, common nitrogen 1,1 times and BDS7 1,7 times less in comparison with river part in centre of Utena town above UAB „Utenos vandenys“. That may be explained by UAB „Utenos vandeys“ affect, which drains large amount of enough refined outlets, attenuate it and decreases water contamination. However river in this part still remains in IV (average contaminated rivers) category measuring by BDS7 , phosphates, mineral nitrogen concentration. According to long terms researches of environment protection specialists in Vyžuona river beside inflowing into Šventoji river measured background BDS concentration was 2,76 mg O2 /l; phosphates concentration 0,037 mg/l, mineral nitrogen concentration 0,59 mg/l. That indicates depuration of the river and belonging to II cleaness class. According to researches of the water plants there was found out that developement and localization of vegetation in watercourse depends on many factors: morfometrical indicators of river, ground of bed and chemical composition of water. However going further to wider watercourse towards river‘s mouth plant community is supplemented with new plant species. Varietals composition of zoobentos and zooplankton shows the suitably cleanness of river water. There was executed experimental fishing in Vyžuona river and caught 8 fish species. Comparing this data and earlier 1991-2001 year data it looks clearly the decrease of fish in the present time. It also can be said that river gets more fishy 6-10 km to mouth.Žemės ūkio akademijaVytauto Didžiojo universiteta