Abstract
A total of 26 water mite species were found in the Mietiulka River at Polesie National Park. The dominants were Limnesia fulgida (35.8%), Neumania vernalis (10.6%), Arrenurus bruzelii (7.6%), and A. batillifer (6.6%). All of the species collected belonged to taxa associated with standing water. Most abundant in the material collected were water mites associated with small pools (73.9%, 12 sp.). Considerably less numerous were vernal species (13.2%, 10 sp.), and tyrphobionts and tyrphophiles (9.4%, 2 sp.), while the proportion of lake species was negligible (3.5%, 2 sp.). The fauna of the Mietiulka river was very similar to the Hydrachnidia communities of standing water bodies in the vicinity. Due to substantial human impact on the river (straightening of the river bed, altered morphometry, hydrological connections with standing water bodies and drainage ditches), species associated with standing water were dominant and there were no taxa typical of river biocenoses. Renaturalization procedures would unquestionably lead to changes in the fauna so that it would be more natural and typical of rivers, with greater proportions of rheobiontic and rheophilic species.