Ecological patterns along two alpine glacial streams in the fitzpatrick Wilderness, Wind River Range, USA

摘要

Most alpine glaciers worldwide are receding rapidly, revealing new streams to be colonized by aquatic organisms. Several major questions are whether these new streams are colonized by aquatic organisms, how fast this colonizing occurs, which organisms are colonizing, and what factors constrain dispersal. We examined longitudinal patterns (over a length of 5 km) in physicochemistry, as well as periphyton and macroinvertebrate composition in 2 glacier streams (Dinwoody, Gannett) in the Wind River Range wilderness, home to the few remaining glaciers in the contiguous USA. We found that newly emerged streams near the glacial snout were inhabited by periphyton and macroinvertebrates, suggesting rapid colonization by biota. Longitudinal (distance from the glacier) patterns were documented in water temperature (increasing), particulate organic carbon (decreasing), particulate phosphorus (decreasing), and benthic organic matter (increasing in Dinwoody). Macroinvertebrate total density and operational taxonomic units (OTUs) also increased with distance from the glacier. Chironomids (Diamesinae) dominated the macroinvertebrate assemblages, a result supporting the importance of water temperature as a controlling factor influencing macroinvertebrate s. Sixteen OTUs were documented, with low-elevation mayflies, stoneflies, and caddisflies occurring at sites with warmer temperatures (>3.0~ °C). Only Diamesinae were found at sites nearest the glacial source where water temperature was <2.0 ~°C As glaciers recede, the physicochemistry of alpine streams will change and likely differ among glacial streams. The mechanistic basis for the consequent effects of these physicochemical changes on freshwater biodiversity is still poorly understood.