THE QUALITATIVE ASSESSMENT OF KOŠEVO STREAM IN TERMS OF WATER FRAMEWORK DIRECTIVE 2000/60/EC BASED ON THE MACROZOOBENTHOS COMMUNITIES

Abstract

Koševo Stream is the right tributary of the river Miljacka. It is formed by Nahorevo Stream and Grončavica in Nahorevo settlement. Stream water quality is a parameter determined by abiotic and biotic factors, which determine the overall ecological status. According to the applied provisions of the WFD, this river (Koševo Stream) is in type 5 - Small and medium-sized plain and mountain rivers with a medium-large bottom substrate, and Nahorevo Stream as a single water body is type 6 - Small and medium-sized hill and mountain rivers with a dominance of large fraction in the bottom substrate. Field research was done in January and July 2021-2023. The analysis included selected physical-chemical and biological parameters. Sampling of benthic macroinvertebrates was done according to the BAS ISO 10870:2014 standard. For the purposes of determining the ecological condition, the following metrics were applied: saprobic index, Shannon-weaver index, BMWP, EPT%, EPT-s, EBI, OSI%. Variations in temperature, pH and oxygen regime initiate changes in the composition of macroinvertebrates, which show the greatest diversity in the samples of Nahorevo Stream. Under the influence of pollution in the downstream part of the Koševo Stream, the degradation of the composition of macroinvertebrates was determined, where the eurovalent representatives of small-bristled insects and preimaginal tadpoles of dipterous insects dominate. The obtained values show that the water of the Nahorevo Stream is in a good ecological condition, and the Koševo Stream is polluted and in a poor ecological condition, especially in the area of the zoo center Pionirska dolina.