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First detailed limnological study was performed from April 2003 to June 2008 in a 396.6 km long section of the Serbian Danube (divided in three parts; from 1260 r-km to 863.4 r-km) to examine community composition and spatial distribution of Mollusca with special attention to the expansion of Ponto-Caspian species, propagation of invasive and introduced species and occurrence of endemic species. Mollusca samples were collected at 15 sites in April, June, September and November. We investigated the spatial distributions and calculated the faunistic similarity of localities with respect to the community composition using the Sørensen Quotient of Similarity. Site variation in analyzed qualitative traits was examined using correspondence analysis. Additionally, the obtained Complete Linkage City-block (Manhattan) distances among sites/parts were subjected to UPGMA (unweighted pair-group method using arithmetic averages) cluster analysis. The class Gastropoda was represented by 18 species from two subclasses (Prosobranchia -six families and Pulmonatathree families).The class Bivalvia was represented by 15 species from four families of order Eulamellibranchiata. Mollusca were represented by 33 species belonging to 17 genera and 13 families. Out of five recorded Ponto-Caspian species in the studied Danube stretch, Lithoglyphus naticoides (Pfeiffer, 1828) and Dreissena polymorpha (Pallas, 1771) are assumed to be invasive species with the highest occurrence frequency (F = 1, each). Four new species in invertebrate fauna for the Danube, denoted as the introduced species -Neozoa, were identified: Theodoxus fluviatilis (L., 1758), Corbicula fluminalis (Müller, 1774), C. fluminea (Müller, 1774), and Sinanodonta woodiana (Lea, 1834). The only endemic species of Gastropoda found in the Danube was Viviparus acerosus Bourguignat, 1862.

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Detailed limnological study of the Lake Srebrno (Serbia) bottom fauna was performed in March 2007. Investigations included qualitative, quantitative, and saprobiological analysis of bottom fauna communities, physical and chemical analysis of sediments and determination of chlorophyll a concentration, as well as saprobic and trophic status analyses. Samples were collected at eighteen sites distributed along a shoreline and in deeper sections of the lake. Twenty taxa from nine macroinvertebrate groups were recorded. Family Chironomidae had the biggest index of participation, the highest species diversity and the largest density of populations in benthocenoses of Lake Srebrno. Faunistic similarity between sites was estimated according to Sorensen’s Quotient of Similarity (QS). The majority of benthocenoses - 56% showed a medium level of faunistic similarity (QS = 21-60%), and 42% of benthocenoses showed a high level of faunistic similarity (QS = 61-100%). The classification of Lake Srebrno based on saprobic and trophic levels was assessed. Saprobic level was in the range from alpha-meso- to poly-alpha-mesosaprobity. The water quality of the lake ranged from class III and between IV and III class. Generally, Lake Srebrno had eutrophic status with the gradation to hypertrophy.