Macroinvertebrate and organic matter export from headwater tributaries of a Central Appalachian stream

Abstract

Headwater streams export organisms and other materials to receiving streams, and macroinvertebrate drift can shape colonization dynamics in downstream reaches while providing food for downstream consumers. Spring-time drift and organic matter export was measured once monthly (February-May) over a 24-h period near the outlets of 12 eastern Kentucky (USA) streams to document and explore factors governing downstream transport. We compared drift measures as loads (day -1 ) and concentrations (volume -1 ) including drift density, biomass, richness, composition, and particulate organic matter across catchment area, month, reach scale factors, and network proximity. Aquatic invertebrate drift densities were roughly 10 times greater than terrestrial invertebrate densities; aquatic richness ranged from 18 to 45 taxa with Ephemeroptera, Plecoptera, Trichoptera, and Diptera genera dominating drift sample richness and abundance. Ordination revealed that assemblages clustered by month and catchment area; organic matter exports (loads or concentrations) also varied by month and catchment area factors. While drift measures were correlated with catchment area and sample date, local factors (e.g., substrate composition, riffle length, channel slope, and network proximity) were generally non-influential. The findings can be used to inform preservation and restoration strategies where headwater streams serve as sources of colonizers and provide food subsidies to receiving streams.

Biological Diversity in Headwater Streams

“…In forestry and agricultural landscapes, headwaters receive little to no protection on average around the world [95], and the past two decades has seen an increased focus on these source streams, mostly for their impacts on water supplies and fish habitats downstream. Headwaters are also important providers of materials and nutrients to downstream environments [96][97][98][99].…”

Effects of extreme high flow events on macroinvertebrate communities in Vermont streams

“…The fact that more dramatic reductions in metrics like richness did not occur suggests that most species were able to find refugia in sheltered microhabitats during the storm (e.g., Fingerut, Fonseca, Thomson, & Hart, 2015), which is not unexpected given that the sites are in healthy, intact watersheds. The good condition of the upstream watershed also increased the likelihood of rapid recolonization by source populations drifting down from upstream (Pond, Fritz, & Johnson, 2016). Sites in watersheds impacted by other stressors may show less resilience and longer recovery time than the streams studied here.…”

The Robinson Forest environmental monitoring network: Long‐term evaluation of streamflow and precipitation quantity and stream‐water and bulk deposition chemistry in eastern Kentucky watersheds

“…Understanding the impacts of surface mining on aquatic ecology, streamwater chemistry and hydrology has also been a major T A B L E 1 Summary of available streamflow and water-quality records for Robinson Forest T A B L E 3 Summary of methods and measurement uncertainties for precipitation and stream-water chemistry analyses (1971-1999; methyl orange titration method); then titration to pH endpoint (pH = 4.5; 1999-2016); subsequently, titration to colour endpoint (metyl orange method). focus of work at Robinson Forest (Agouridis et al, 2017;Burke et al, 2014;Fritz et al, 2011;Hutton et al, 2020;Mastin et al, 2012;Muncy et al, 2014;Pond et al, 2016;Price et al, 2016;Price et al, 2018;Strohm, 2014;. The network has been utilized to evaluate the effectiveness of forestry best management practices for protecting water resources (Adkins et al, 2016;Barton et al, 2017;Bowker et al, 2020;Maigret et al, 2014;Witt et al, 2013;Witt et al, 2016).…”