Physico‐chemistry and aquatic insects of a glacier‐fed and a spring‐fed alpine stream

Abstract

1. Physico‐chemical conditions and benthic macroinvertebrates were studied in two adjacent alpine streams in the Tyrolean Alps, Austria, for 2 years, and aquatic insect emergence was recorded for 1 year. 2. In the spring‐fed system, maximum discharge and increased concentrations of suspended solids, nitrate and particulate phosphorus occurred during snowmelt in June. In the glacier‐fed stream, high discharge and strong diel fluctuations in flow and concentrations of suspended solids created a harsh and unstable environment during summer. Glacial ablation, variation in groundwater inflow, and water inputs from tributaries draining calcareous rocks caused water chemistry to vary both seasonally and longitudinally in glacier‐fed Rotmoosache. 3. A total of 126 aquatic or semi‐aquatic invertebrate taxa were collected, 94 of which were found in the glacier‐fed stream and 120 in the spring‐fed stream. Chironomid abundance was 2–8 times and taxa richness 2–3 times lower in the glacier‐fed stream than in the spring‐fed stream, as was the number of chironomid taxa (72 versus 93 total). 4. These results broadly support the conceptual model by Milner & Petts (1994) concerning glacier‐fed stream systems. However, single samples and seasonal means showed relatively high invertebrate abundance and richness, especially during winter, indicating a considerable degree of spatial and temporal variability. 5. We suggest that the seasonal shifts from harsh environmental conditions in summer to less severe conditions in autumn and a rather constant environment in winter are an important factor affecting larval development, life‐history patterns and the maintenance of relatively high levels of diversity and productivity in glacier‐fed streams.

Biotic responses to multiple aquatic and terrestrial gradients in shallow subarctic lakes (Old Crow Flats, Yukon, Canada)

“…Variation in input waters to alpine streams is associated with differences in physicochemical conditions and the diversity and richness of diatom and chironomid communities (Füreder et al 2001;Robinson and Kawecka 2005;Roy et al 2011). However, comparable research incorporating knowledge of source-water input and multiple environmental gradients has not yet been undertaken to discriminate their direct and indirect influence on benthic biota in northern lakes and ponds.…”

Large-scale environmental controls on microbial biofilms in high-alpine streams

“…For in-stance, discharge from small nival tributaries draining elevated sub-catchments are insignificant during this hydrological period when streamwater largely originates from subglacial and groundwater sources (cf. Füreder et al, 2001;Smith et al, 2001). This contrasts with snowmelt and ablation as periods of higher hydrological linkage that reduce the geochemical similarity between the hypokryal and metakryal sites.…”

“…Growing awareness of alpine streams as sensitive indicators for global change has recently fostered the development of various models predicting the structure of macroinvertebrate communities in glacial streams (e.g., Smith et al, 2001;Füreder et al, 2001). Biofilms constitute a link between hydrogeochemistry and benthic invertebrates, and we thus consider our findings as a stimulus to complement these models by explicitly integrating the coupling between terrestrial/aquatic connectivity, hydrogeochemistry and microbial ecology of alpine streams.…”

“…Despite the awareness that alpine aquatic ecosystems are particularly prone to climate change (Chapin and Körner, 1994;McGregor et al, 1995), the response of this predictable seasonal variation to global warming and its consequences for community and ecosystem ecology remain poorly understood. While considerable effort has addressed the influence of glacial dynamics on algal and especially macroinvertebrate communities (Hieber et al, 2001;Peterson et al, 2001;Füreder et al, 2001;Burgherr et al, 2002), virtually nothing is known on the microbial ecology of alpine streams (Battin et al, 2001;Logue et al, 2004). The central objective of the present paper is to study the variability of stream microbial biofilms within a glacial floodplain and to assess the influence of glacial ablation and snowmelt as major hydrologic factors determining the physical template for stream biofilms.…”

Downscaled GCM projections of winter and summer mass balance for Central European glaciers (2000–2100) from ensemble simulations with ECHAM5‐MPIOM

“…It was shown in several studies that glacial melt-water plays an important role in Alpine river-flow conditions (Huss et al, 2008;Koboltschnig et al, 2007Koboltschnig et al, , 2008. Besides their effect on the amount of river discharge, which is also important in the context of Alpine power production, glaciers are important for the low temperature of glacial rivers and as such in turn to the quality of the fish distribution, for instance (Füreder et al, 2001).…”