1. High climatic sensitivity and lack of significant human impact make alpine river basins important environments for examining hydrological and ecological response to global change.
2. This paper is based upon previous and ongoing research within a glacierized, alpine river system (Taillon-Gabiétous basin, French Pyrenees), which adopts an interdisciplinary approach to investigate the climate-hydrology-ecology cascade. Data are used to advance hypotheses concerning impacts of climate change/variability upon alpine river system hydrology and ecology.
3. The snowpacks and glaciers that are the source of Pyrenean streams are climatically sensitive, with glaciers in retreat for most of the historical period. Given anticipated changes in summer air-mass frequencies, the volume of meltwater may decrease, the nature and rate of glacier drainage may alter, and the timing of peak snow- and ice-melt may shift. However, rainfall-runoff and groundwater may increase their relative contributions to stream flow.
4. The influence of changing water source contributions on physico-chemical habitat and, in turn, on benthic communities is assessed using an alternative alpine stream classification. This model predicts more rapid downstream change in benthic communities in the future as meltwater contributions decline and, at the basin-scale, biodiversity may be reduced owing to less spatio-temporal heterogeneity in water sources contributions and, thus, physico-chemical habitat. However, predictions are complicated by potential changes in biotic interactions with altered species' distributions.
5. Integrated, long-term research into the climate-hydrology-ecology cascade in other alpine river basins is vital because interdisciplinary science is fundamental to predicting stream hydrology and ecology under scenarios of future climate/variability, to assessing the utility of alpine river systems as indicators of global change, and to developing conservation strategies for these fragile ecosystems.