Summary:

Changes in ground beetles assemblage structure in relation to bankfull discharge in mountain stream have been tested. The research was performed in one of the Polish Carpathian streams in the Gorce Mountains region: the Ochotnica Stream. As the index of determination of bankfull volume the size of terrestrial invertebrates (carabids) was advocated which were present in the investigated research cross-section and were resistant to specific water discharge conditions. Redundancy analysis shoved that only variation of community biomass depended on frequency of changing water discharge. Distribution of mean abundance in body length classes is unimodal for upper benches meanwhile on the lowest bench abundance decreased linearly. This parameter can be used in practice as a good indicator of bankfull discharge on mountain streams. The need of fluvial processes in conservation approach for riverine communities is discussed.