The relationship of carabid beetle species occurrence patterns and environmental variables characterising the hydrological regime has been studied at the River Elbe in Central Germany. Both flood duration and groundwater depth had major influence on species assemblages as the ordination of study plots mainly followed a gradient along these two variables. The simultaneous ordination of the plots according to species occurrence and environmental parameters showed a highly significant joint structure with the first two axes of a co-inertia analysis, explaining >98% of the variance. A total of 27 species out of 129 caught fulfilled criteria of fidelity and specificity to the plots of the five clusters revealed by their abiotic conditions and were sufficiently abundant to be suitable indicators for one or a combination of clusters of plots. IntroductionNatural features of European floodplains are the result of dynamic geomorphological processes that lead to a high habitat diversity of these ecosystems (GERKEN, 1981;GERKEN, 1992a;WARD, 1998;WOLFERT et al., 2001). Due to their heterogeneity in space (habitat mosaics) and time (habitat change), natural riverine landscapes are characterised by a highly adapted and diverse flora and fauna (ROBINSON et al., 2002). However, in recent decades Central European floodplains were affected by a severe decline in biodiversity (GODREAU et al., 1999), due to loss of habitats (and thus species) mainly caused by changed water regimes and increased land use pressure on these ecosystems. Hence, floodplains are considered as landscapes with high conservation value and protection needs and have become a focus of conservation research (FOECKLER and BOHLE 1991;GERKEN, 1992b;AMOROS and PETTS, 1993;YOUNG, 2001;JESSEL, 2005;SCHOLZ et al., 2005).Floodplain management and conservation requires a sound understanding of species-environment relationships and suitable bioindicators to assess and monitor ecological conditions, since parameters characterising the hydrological regime are time consuming to measure and