Water Sources and Habitat of Alpine Streams

Abstract

We review the different water sources of alpine streams, namely snowmelt, glacial meltwater, and groundwater. Alpine water sources have different physicochemical properties, with their relative contributions determining habitat characteristics of receiving streams. High spatio-temporal variability of water source contributions makes rivers in alpine glacierized basins distinct from other lotic systems. The timing and volume of bulk (snow and ice) meltwater production, along with inputs of groundwater generate distinct patterns of stream discharge, water temperature, suspended sediment, hydrochemistry and channel stability over annual, seasonal and diurnal time-scales. These temporal changes in water sources are sensitive to anthropogenic pressures including climate change, water resource allocations, and contaminants which will ultimately influence water quality and habitat suitability for biotic communities. Heterogeneity of the physicochemical environment creates a spatial and temporal mosaic of stream habitats related to differences in water source contributions, and hydrological connectivity. Hydrochemical characteristics are strongly influenced by seasonal snowmelt, and the development of glacier drainage systems. River ice is a particular feature of alpine streams, creating unique environmental conditions that strongly affect the flora and fauna, both directly, and indirectly through changes in their environment. The extent, nature and duration of river ice varies widely across alpine areas. We outline the characteristic longitudinal patterns in benthic macroinvertebrate communities downstream from these water sources created by this physical template.