Saprobiological analysis of water of the Nišava river (first odrer tributary of the Southern Мorava river) in South-Eastern Serbia on the basis of macrozoobenthos as a bioindicato

Abstract

The saprobiological water analysis of the river Nišava was carried out using the macrozoobenthos organisms as the bioindicator. The samples were collected with the Surber net, seasonally during the period of 2001 to 2003, from nine localities along the water course of the river Nišava. The total lengthe of the river Nišava, with the river Ginska, is 196,9 km (of which in Serbia is 151 km). The river basin has an area of 4084,6 km2 (in Serbia is 3933,6 km2). while the remaining part is in Bulgaria. Using the indicator properties of 104 macroinvertebrate species, at all the studied localities along Nišava River (the lenght of the studied part is 139 km), was recorded and absolute dominance of the organisms bioindicators of beta-mesosaprobity, whose presence characterizes water of quality class II. The quality of water has been measured by using the saprobity index according to the Puntle-Buck, the Knopp and the Rothschein methods. Basedn od average value of the saprobity index according to the Punte-Buck methos, in the river Nišava, the highest values were recorded at the profiles Ni1 (2,03) and Ni7 (2,37), and the lowest value at the locality Ni5 (1,94), but downstream due to ability of self-purification there is significant improvement of water quality ot locality Ni6 (1,85). Based on the Knop methods it was determined that frin 2001 ti 2003 the highest average value of the ralative purity of water was at profile Ni6 (90,39%) while the highest values of the relative saprobity of water quality was found on profile Ni1 (35,35%). Using the method of Rothschein the best average quality of water was found at profile Ni3 (55,30) while using the method of Punte-Buck the best quality of water was found at the profile Ni2. Explanation of this deviation is because at the third locality (although, it is located 1 km downstream of the city Pirot and it is constantly exposed to influexes of the urban industrial and communal waste waters into the river stream) there are dominant processe of autopurification. The lowest average value of the saprobity index using the Rothschein method, including the Puntle-Buck method and the Knop method was found at the prifile Ni (22,86),