engleski

Aquatic molluscan fauna (Mollusca: Gastropoda, Bivalvia) of the Vrana Lake Nature Park (Croatia)

This paper presents the results of a malacological survey of Vrana Lake and its surroundings in Vrana Lake Nature Park. The main aim of this research was to provide an inventory of aquatic molluscs, examine their population densities, and establish the occurrence of endangered as well as non-native molluscs and their possible impacts on native molluscan assemblages. A field study was conducted from August 2009 to December 2011. Out of 18 examined sites, the majority (16 sites) were located in Vrana Lake Nature Park, while 2 sites were outside of the park. Altogether 21 species of aquatic non-marine molluscs (15 gastropods, 6 bivalves) have been recorded. Out of all recorded species, only 10 were documented in Vrana Lake, probably due to the higher salinity of water in the lake. The most common species recorded were Theodoxus fluviatilis, Bithynia tentaculata, Acroloxus lacustris and Stagnicola fuscus, while Heleobia stagnorum, Radix auricularia and Hippeutis complanatus were found only occasionally. Only one non-native and invasive mollusc Dreissena polymorpha was recorded but despite detailed research only empty shells were found. In canals northwest of the lake (Lateral canal, Main canal) the occurrence of 17 species was documented. Among them, specimens of 8 species were found alive: T. fluviatilis, B. tentaculata, A. lacustris, S. fuscus, R. auricularia, H. complanatus, Ancylus fluviatilis and Pisidium casertanum. A population of the endangered gastropod Anisus vorticulus was found in Benča Lake and together with this species, B. tentaculata, A. lacustris, S. fuscus, H. complanatus and P. obtusale occurred. Outside of the nature park in the canal in Jasen only populations of S. fuscus were recorded. In the spring and small brook near the cave Pećina we found numerous living populations of three species (Islamia cf. pusilla, Valvata cristata, Paladilhiopsis cf. solida), which were recorded only at this site. During the study three species of gastropods and four species of bivalves, including non-native and invasive D. polymorpha, were recorded only by empty shells.

Mollusca; Gastropoda; Bivalvia; Anisus vorticulus; Vrana Lake; faunistics

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