Anthropogenic pressures and their impacts on the hyporheic zone: ecological implications for gravel spawning fish

摘要

To study the structures and functions of the hyporheic zone in running waters under anthropogenic pressures and to detect key processes in the habitats of gravel spawning fish, an extensive study was carried out at the River Lahn (Germany). In this article we present results of the River Lahn investigation as part of a wider study on fish spawning conditions at the River Diemel and the River Ulster (study sites detailed in Table 1). The vertical hydraulic exchange of water and water constituents were identified as key processes in the functioning of the hyporheic zones. These processes were influenced by abiotic factors (discharge, sediment transport, emissions of oxygen-consuming organic material deriving from point and diffuse sources) as well as by biotic factors (periphy-ton biomass dynamics, microbial nutrient turnover, bioturbation). The latter appears to be underestimated in river ecology, and biotic control of hyporheic functions may be much more important than generally assumed.