Riverine ground beetles as indicators of inundation frequency of mountain stream: a case study of the Ochotnica Stream, Southern Poland

Effect of inundation frequency on carabid beetle assemblage structure and organization were studied in single cross-section of mountain stream. A non-metric multidimensional scaling performed on the Bray-Curtis matrix of similarity clearly divided assemblages from lower, flooded at least 1 time per year and upper elevation, flooded every two or more years. Mean species abundance, biomass and mean individual biomass were significantly lower in more frequently disturbed plots. Analyzing infrequently and frequently flooded sites jointly and separately co-occurrence pattern was clearly non-random with c-score values higher than random means, indicating segregation processes even among highly disturbed sites. Twenty nine species were significantly related to flood frequency (IndVal analysis), nine of these were indicators for frequently flooded sites with significantly lower mean body biomass. Our findings confirm the hypothesis of decreasing body size in relation to disturbance in riverine ground beetle assemblages.