A global ecosystem - Groundwater is alive!

Groundwater is an ecosystem of global extent with very special living conditions such as lack of sunlight, narrowness of space in the interstices of sand and gravel, low but constant temperatures, and limited nutrient resources. Despite these conditions subterranean biocenoses have a diverse structure and abound in species of bacteria, protozoans, fungi and metozoans. The activities and interactions of these organisms have a significant effect on the flux of organic and inorganic matter and on groundwater quality. After passing through the soil only rather low concentrations of dissolved and partly also particulate organic matter reach the groundwater. There they are used by heterotrophic bacteria and fungi to produce the biomass supporting other organisms. Comparatively low biomass but high diversity in species composition and bioactivities are typical for life in the groundwater environment. Slowed-down metabolism and rates of reproduction are also typical and are responsible for the sensitivity of groundwater systems to disturbances from outside. Each group of organisms serves a variety of functions in maintaining the stability of subterranean communities. Sustainable groundwater protection therefore is impossible without the protection of these communities.