Fish species microhabitat preferences in small streams

FISH SPECIES MICROHABITAT PREFERENCES IN SMALL STREAMS This study assesses microhabitat preferences of selected fish species in the environment of small watercourses. The research was carried out at three localities in the Křivoklátsko Protected Landscape Area (the upper and lower part of the Úpoř stream and the Klíčava stream) between 2004 and 2006. Parameters including average water flow, average depth, presence of shelters, width of the watercourse and cover of individual substrate types were monitored in permanent profiles. These sections were then repeatedly electrofished over a course of three years (from April to October of each year). Over 10,000 fish were caught altogether. Relationships between fish species and the environment were analysed at two levels of detail. In all species, preferences towards different 60 m long sections of the watercourse were tested. In small benthic species, namely the common bullhead (Cottus gobio) and the stone loach (Barbatula barbatula), which did not exhibit conspicuous habitat shifts during electrofishing, preferences to three-metre sections of the watercourse were also assessed. Relationships among individual species and between species and their habitats were analysed using both indirect and direct multidimensional linear methods (PCA, RDA) in Canoco..