Responses of Low Arctic Stream Benthic Macroinvertebrate Communities to Environmental Drivers at Nested Spatial Scales

We explored the importance of environmental drivers in structuring benthic macroinvertebrate communities along a spatial hierarchy (local to landscape scale) in Low Arctic stream systems that were previously unstudied. Macroinvertebrate communities from 29 sites in Low Arctic areas of northern Labrador and Quebec, Canada, were quantified by taxonomic structure and biological metrics. Environmental variables were quantified at site, reach, and catchment scales using field-collected data and geospatial information. The first three axes of Redundancy Analysis (RDA) ordinations explained 21.0-40.6% of the unconstrained variance in taxonomic structure and biological metrics. Biological data were most highly correlated with site-scale variables, but variables at each spatial scale were highly correlated with community structure. Across all scales, one of the strongest gradients involved environmental drivers that could be associated with habitat structure and instability. Abundance of the chironomid subfamily Diamesinae, a tolerant taxon in high-latitude and high-elevation systems, was highly positively associated with this habitat gradient. This hierarchical framework provides a knowledge base for the development of a sustainable long-term monitoring approach for Low Arctic aquatic ecosystems. By incorporating measures of environmental drivers at multiple spatial scales, future monitoring efforts may more effectively respond to current and future pressures on aquatic biodiversity.