In this study, we focused on the analysis of diversity and taxonomic structure of macroinvertebrates communities in the rivers Bistrica, Sotla and Mestinjščica. The Bistrica River, part of the Sotla River and their catchments are in the Kozjansko Regional Park and the Kozjansko Natura 2000 Protected Area, while all three rivers are within Sotla with its tributaries Natura 2000 Area, which includes only the riverbed and part of their riparian areas. We investigated whether the higher formal protection of the catchment affects the macroinvertebrate community and the quality of the rivers. We used standard kick sampling method to sample macroinvertebrates. Based on macroinvertebrate community structure, we calculated various diversity (D, d, H') and biotic indices (EPTO, EPT, GOLD, ASPT, BMWP, TBI). We also measured chemical, physical and hydro-morphological parameters at the sampling sites, assessed substrate structure and adjusted RCE index. Using correlation analysis, we investigated relations between environmental factors, indices, and feeding groups of macroinvertebrates. We detected 5049 individuals belonging to 16 higher taxa and 68 families. We ascertained that the Bistrica River was the least polluted and degraded. The sampling sites of the river Sotla, located in the Kozjansko Regional Park and Natura 2000 Area, were not polluted or degraded, unlike the third site, closest to the spring, of that river. We can conclude, that the River Mestinjščica, which is included only in the Natura 2000 Protected Area Sotla with tributaries, is the most polluted and degraded. In some of the sampling sites on that river there was no riparian zone, and the macroinvertebrate was dominated by Oligochaeta and Diptera, both indicators of pollution.
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