Distribution of freshwater sponges in Serbia

Abstract

As data on the distribution of freshwater sponges (Porifera, Demospongiae, Spongillida) in Serbia are extremely scarce, we investigated the main Serbian rivers and lakes with respect to Porifera occurrence, for which 17 lotic and 11 lentic water bodies were selected. Sponges were found in 11 of 17 rivers (62 specimens in total) and in 3 of 11 lakes/reservoirs (seven specimens in total). Classical morphological spicule analysis was coupled with polymerase chain reaction (PCR) and gene sequencing for species identification. Among the 69 collected speci- mens, five sponge species of the family Spongillidae have been identified: Ephydatia fluviatilis (Linnaeus, 1759), Spongilla lacustris (Linnaeus, 1759), Ephydatia muelleri (Lieberkühn, 1856), Trochospongilla horrida Weltner, 1893, and Eunapius fragilis (Leidy, 1851). The most frequently found sponge in Serbian rivers was E. fluviatilis (45% of all specimens), while the least frequent was E. fragilis (6 % of all specimens). The Tisa river has the highest sponge diversity (four species). In lentic water bodies, only E. fluviatilis (four specimens) and S. lacustris (three specimens) were found. In general, sponges were infrequent and their abundance was low in Serbian fresh waters. While sponges seem to tolerate significant variations of physical and chemical parameters, some optimal values can be established.