Environmental and spatial control of ostracod assemblages in the Western Carpathian spring fens

Abstract

The effect of environment and species dispersal limitations may both significantly affect the structure of ecological metacommunities but there have been a relatively few attempts to separate their effects in aquatic assemblages. In this paper, we tested the relative importance of environment and space on the ostracod assemblages on a regional scale (encompassing ca 15,800 km2) in 74 permanent helocrene springs. We used Canonical Correspondence Analysis and Variation Partitioning to test the unique and shared effects of environment and space, represented by Principal Coordinates of Neighbor Matrices. We found that ostracod assemblages were significantly influenced by environment (mainly the mineral content and TOC) and space (roughly the west-east direction); the shared effect was relatively low. A unique effect of space was found for both species strongly associated with spring habitats and for euryoecious species found in the springs. We suggest that the passive dispersal in ostracods is random and infrequent between the isolated spring fens and produces spatially structured assemblages.