In this study, we analyzed changes to gastropod assemblages with regard to the seasonal variations of discharge, substrate composition and temperature in 19 springs in northwestern Bosnia and Herzegovina. Six aquatic gastropod species were identified, including Bosnidilhia vreloana Boeters, Gl?er & Pesic, 2013 and Islamia dmitroviciana Boeters, Gl?er & Pesic, 2013, two species endemic for the studied area. Surprisingly, we did not observe a significant influence of discharge on the composition of gastropod assemblages in the studied springs. This could mean that gastropod assemblages in the springs examined are well adapted to intermittent conditions (i.e. fluctuations in discharge). The results of canonical correspondence analysis (CCA) showed that specific substrate types can be good predictors for the occurrence of particular species. Interestingly, we found that spring specialists such as Bythinella schmidti and Islamia dmitroviciana also inhabit springs with intermittent dry periods. The studied springs should be considered at risk and some of their gastropod dwellers, such as the endemics Bosnidilhia vreloana and Islamia dmitroviciana, are possibly endangered, requiring conservation planning to protect these spring habitats.

Knowledge and management of aquatic ecosystems (formerly Bulletin Français de la Pèche et de la Pisciculture), an international journal on freshwater ecosystem

Springs are spatially restricted ecotones usually found at the beginning of a headwaters continuum, which provide distinct environmental conditions, and are inhabited by invertebrate spring specialists called cre- nobionts. Springs along rivers of higher order with short springbrooks oppose the classical eucrenal-hypocrenal-epirhithral continuum and may be colonised differently. Here, 35 rheocrene springs along the river Cvrcka in the Dinaric Karst are investigated, with the aim to identify the role of river connectivity on the species assemblages in springs, and to test whether the large proximity of some springs influences the similarity of their species composition. Species assemblages are strongly dominated by generalist rhithrobiontic taxa, which also occur in the adjacent river. Flooding significantly influences the composition of the species assemblages, with a higher share of rhithro-biontic taxa in flooded springs. Connectivity and distance to the river do not have a significant influence, and spatial proximity is not an indicator for assemblage similarity. The springs are strongly influenced by the river Cvrcka. We conclude that dispersal and colonisation mainly take place via the watercourse corridor by insects in adult stages. Conservation strategies must take into account the special character of riparian springs along large rivers.