SUBSURFACE DWELLING CRUSTACEANS AS INDICATORS OF HYDROLOGICAL CONDITIONS, OXYGEN CONCENTRATIONS, AND SEDIMENT STRUCTURE IN AN ALLUVIAL AQUIFER

The relation between environmental conditions and the species composit ion and individual abundance of crustaceans was investigated in a shal low alluvial aquifer, located in the Danube wetlands (Lobau, Austria). Samples, consisting of groundwater, sediment, and fauna, were taken f rom permanent installed wells by means of a piston pump five times in a year cycle. The results show that the spatial and temporal distribut ion, individual abundance, and species richness of crustacean fauna is related to hydrological conditions, oxygen concentrations, and geolog ic structures in the alluvial aquifer. Therefore, crustaceans, divided in stygoxene, stygrophile, and stygobite species, can be used as bioi ndicators of these environmental conditions in an aquifer. It is sugge sted that beside physicochemical analyses also the crustacean fauna sh ould be considered to characterise a groundwater ecosystem.