Alpine Glacial Stream Ecology

Alpine glaciers world-wide are retreating at unprecedented rates, causing new stream ecosystems to emerge and be colonized by aquatic organisms. To better understand how these sensitive alpine ecosystems are affected by this landscape transformation, we examined the aquatic macroinvertebrates colonizing newly emerged glacial streams in the Swiss Alps and Wyoming's Wind River Range. Algae and macroinvertebrates are among the first organisms to colonize these new stream ecosystems. Macroinvertebrates are sensitive to changes in temperature, chemistry, organic resources, and water velocity, thus making excellent indicators of environmental change. Newly emerged streams from eight glacial systems in Switzerland and the Dinwoody and Gannett glaciers in the Wind River Range were analyzed for water chemistry, periphyton and macroinvertrebrates. Water chemistry showed highly dilute concentrations of solutes (particularly nutrients) and was relatively acidic. However, all streams were productive enough to support insect colonization at the glacier snout. Macroinvertebrate density and taxon richness exhibited low values near the glaciers. Macroinvertebrate density increased longitudinally in concert with increases in organic resources. Chironomidae were found in highest abundance, especially by various species of the alpine specialist Diamesa. Macroinvertebrates rapidly colonized new glacier streams, thereby acting as important indicators of larger ecosystem changes.