engleski

Microhabitat preferences by aquatic invertebrates in the Zrmanja River springhead

Karstic springs are among the most complex ecotonal environments with specific transition zones based on hydromorphological properties. Nevertheless, most ecological studies of spring assemblages are based on distribution differences between crenal spheres (i.e. eucrenal vs hypocrenal). The ecological study of benthic invertebrates in the Zrmanja River springhead was focused on spring microscale in order to provide deep insights into fauna's preferences of key physical variables. During April 2016, we collected 40 subsamples in dominant microhabitats (i.e. substrates with high and low water velocity) using the hand net according to modified AQEM procedure. The springhead assemblages were generally dominated by its temporal residents, Diptera and Ephemeroptera. The prevalence temporal fauna were Chironomidae, being the most abundant at the moss in the low water velocity. According to the EPT index, the highest EPT taxa richness was recorded in moss on the macrolithal and megalithal substrates exposed to the high-velocity water flow. In the mesolithal, predatory Plecoptera (Perlidae) were positioned at the top of the food web in the low water velocity, while they were replaced by Trichoptera(Rhyacophyllidae) in the high water velocity. Hydrachnidia, as a key spring fauna, were recorded mostly at microhabitats with low water velocity within the microlithal. We confirmed Reiss and Chifflard conceptual model of eucrenal as a heterogeneous mosaic-like patches and recorded heterogeneity on multiple levels.

aquatic invertebrates ; karstic spring ; microhabitats ; water velocity ; heterogeneity

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