Macroinvertebrate Inventory of High Elevation Springs in Shenandoah National Park

Girgente, Hannah; Underwood, Megan; Tabor, Lisa; Haney, Sydney; Swarm, Hannah; Entrekin, Sally

Shenandoah National Park contains hundreds of natural springs which help form the headwaters of three major watersheds (the Rappahannock, Shenandoah, and James rivers) that empty into Chesapeake Bay. Virginia Tech partnered with the National Park Service Inventory and Monitoring program to sample macroinvertebrates and environmental measures related to water quality, habitat availability, and human use at 63 springs within the park, of which, 59 could were assessed and analyzed. 34 Thirty five of the 59 springs had been intentionally modified for human use via spring box or pipe installation and the remaining 25 had not been modified. The goals of this inventory were to assess the distributions of macroinvertebrates across springs in the park with an emphasis on identifying unique spring specialist taxa that might be considered rare (i.e., species experiencing steep population declines with an increasing risk of extinction). Additionally, we sought to determine whether macroinvertebrate diversity and the presence of rare taxa have been impacted by modifications made to springs and/or by visitor use (springs that are frequently visited/used by park goers). We identified 205 unique taxa across the 59 springs. Of those taxa, we identified 17 rare taxa using NatureServe’s Conservation Status Rank (species with a status rank of at least vulnerable were labeled rare). Rare taxa were present in 32 springs, 19 of which were modified (having a spring box or pipe installed) and 13 were unmodified (no installations). Class Insecta represented 90% of rare taxa that were mostly in orders Trichoptera, Plecoptera, Ephemeroptera and Odonata. There was no difference in total taxa richness or abundance between the spring types. Richness and abundance for all taxa and for rare taxa were greater, on average, in modified springs; however, these differences were not statistically significant. Insect orders Ephemeroptera, Plecoptera and Trichoptera (collectively known as EPT) tend to be more sensitive to environmental change than other aquatic insect orders, and showed no compositional differences between spring types, but had greater average values of taxa richness and abundance in modified springs. This trend was also observed in Plecoptera, alone. General linear models indicated decreased pH, flow (velocity), small woody debris, and increased proximity of springs to a spring signpost as factors associated with increased taxa richness in the macroinvertebrate community while richness for rare taxa were most associated with increasing temperature, small woody debris, and increased distance (decreased proximity) of springs to a spring signpost. Furthermore, linear models showed that decreasing pH, flow, temperature, small woody debris, and increased proximity of springs to a spring signpost or Appalachian Trail shelters (referred to as AT huts) were associated with increased abundance of macroinvertebrate taxa while decreases in temperature, increased cobble substrate, and increased proximity to spring signposts were associated with greater abundances of rare taxa. The diversity of spring types, locations and habitats appear to support a diversity of species that are not being negatively affected by visitor usage or spring box infrastructure. The springs provide a regional species pool at high density that are likely source populations for the headwater streams.

Macroinvertebrate Inventory of High Elevation Springs in Shenandoah National Park

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