Reference conditions for fish microhabitat use in foothill streams: A case study on undisrupted carpathian streams

Abstract

ABSTRACTFoothill rivers characterized by a relatively high slope are frequently used for hydropower purposes or are highly regulated. These river sections are inhabited by many rheophilic species that are endangered by habitat degradation. Restoration/rehabilitation projects and fishway constructions could increase species favourable status, but relevant ecological requirements for several fish species are missing. We present a first insight into a complex microhabitat use of all species (excluding rare species) occurring within the model foothill stream and provide a comprehensive view on the most important microhabitat variables that influence the distribution of fish species within the model area. For two species, Balkan spined loach (Sabanejewia balcanica) and Carpathian barbel (Barbus carpathicus), we present the first description of such microhabitat use. The model we present (canonical correspondence analysis) significantly explains 64.5% (p < 0.01) of the variability, where water depth more than 40 cm, refuge stones and microhabitats in the bank area are the most influential microhabitat variables. Moreover, three species groups are apparent from the graphical expression of our proposed model, where species from the upper sites form the first group, young‐of‐the‐year, Balkan spined loach and common minnow (Phoxinus phoxinus) form the second group and abundant species inhabiting foothill river sections form the third group. In general, we assume that the preferences of a species for a given microhabitat are not only a function of, e.g. environmental variables or species length frequencies, but also strongly depend on the co‐occurring species. Copyright © 2010 John Wiley & Sons, Ltd.