Aquatic insect assemblages associated with subalpine stream segment types in relict glaciated headwaters

Abstract

Aquatic habitats and biotic assemblages in subalpine headwaters are sensitive to climate and human impacts. Understanding biotic responses to such perturbations and the contribution of high‐elevation headwaters to riverine biodiversity requires the assessment of assemblage composition among habitat types. We compared aquatic insect assemblages among headwater stream segment types in relict glaciated subalpine basins in Mt. Rainier National Park, Washington, USA. Aquatic insects were collected during summer and autumn in three headwater basins. In each basin, three different stream segment types were sampled: colluvial groundwater sources, alluvial lake inlets, and cascade‐bedrock lake outlets. Ward's hierarchical cluster analysis revealed high β diversity in aquatic insect assemblages, and non‐metric multidimensional scaling indicated that spatial and temporal patterns in assemblage composition differed among headwater stream segment types. Aquatic insect assemblages showed more fidelity to stream segment types than to individual basins, and the principal environmental variables associated with assemblage structure were temperature and substrate. Indicator species analyses identified specific aquatic insects associated with each stream segment type. Several rare and potentially endemic aquatic insect taxa were present, including the recently described species, Lednia borealis (Baumann and Kondratieff). Our results indicate that aquatic insect assemblages in relict glaciated subalpine headwaters were strongly differentiated among stream segment types. These results illustrate the contribution of headwaters to riverine biodiversity and emphasise the importance of these habitats for monitoring biotic responses to climate change. Monitoring biotic assemblages in high‐elevation headwaters is needed to prevent the potential loss of unique and sensitive biota.

Longitudinal changes in stream invertebrate assemblages of Grand Teton National Park, Wyoming

“…This result is similar to other studies in North America (e.g. Finn & Poff, ; Brown et al ., ; Kubo et al ., ), and fits in with a broader hypothesis that greater environmental diversity in headwater basins contributes to more diverse invertebrate assemblages (Finn et al ., ). Among streams, variation in dispersion was present but when categorised by elevation, the greatest dispersion was clearly seen among middle and high elevation sites, with the least dispersion at low elevation sites.…”

“…Water sources (lake, snowmelt, spring, etc.) in headwater streams may cause much of the observed variation (Kubo et al ., ). Non‐insect invertebrates do not have an aerial stage and their predominant mode of dispersal is likely within the stream channel.…”

​Diversity, Abundance and Composition of Ground Beetles (Coleoptera: Carabidae) in Jhunjhunu District of Rajasthan, India

“…Site-D (banks of water bodies) also has low species diversity and species richness because of low forging sites and little availability of microhabitats for carabid beetles. The pattern of species diversity and composition indicated habitats related with assemblage structure of vicinity area of water bodies (Kubo et al, 2013).…”

New Distributional Data for the Northern Forestfly, Lednia borealis Baumann and Kondratieff, 2010 (Plecoptera: Nemouridae), in Washington, USA

“…It is also included as a Species of Greatest Conservation Need in the Washington State Wildlife Action Plan (WDFW 2015). It has been collected primarily from high elevation cold water habitat, including lakes, glacial-fed streams, and flowing springs in the Cascade Mountains (Kondratieff and Lechleitner 2002, Baumann and Kondratieff 2010, Kubo et al 2013, Fallon and Blevins 2020. It should be noted that Lednian species may be particularly at risk from climate change impacts such as receding glaciers, reduced snowfall, loss of perennial snowpack, and warmer summer water temperatures (Giersch et al 2016).…”