McMillan, Melanie2023-06-082023-06-082023-06-07vt_gsexam:37549http://hdl.handle.net/10919/115370Benthic macroinvertebrates are heavily relied on to indicate stream condition because of their ease of sampling, broad span of sensitivities to pollution among taxa, and diverse life histories that utilize various habitats and environmental conditions. Surface-coal mining in central Appalachia often results in salinization of headwater streams, with documented responses in macroinvertebrate communities across streams that vary in specific conductance (SC), an index of degree of salinization. Mining-influenced headwater streams can also exhibit within-stream spatial variation in SC, frequently via dilution with downstream distance from mining. However, the extent to which coal-mining alters downstream patterns in water chemistry and macroinvertebrate communities is largely unknown. This study aimed to determine macroinvertebrate community responses to physical and chemical gradients within six Appalachian headwater streams (four mining-impacted, two reference). Streams were sampled for benthic macroinvertebrates, habitat characteristics, and water chemistry in fall 2021 and spring 2022 at six-to-nine locations per stream over a range of 1.5 – 3 km. Mining-impacted streams exhibited greater spatial variation in macroinvertebrate community composition compared to reference streams, particularly in spring. Bray-Curtis Community similarity determined highly-impacted streams experienced the greatest within-stream shifts in community similarity. Metrics of macroinvertebrate communities and community similarity showed some correlation with SC at within-stream scales, particularly in highly impacted streams in spring; however, such trends were much fewer and weaker compared to relationships among streams when collectively examining communities. Redundancy Analysis (RDA) and Variation Partitioning (VP) indicated water quality, habitat, and location do overlap in explanation of community variation although they often additionally explain variance in unique ways. Significant variables identified by RDA within at least two of the six streams include channel slope, streamwater nutrients and hardness, stream channel embeddedness, and percent fines comprising the streambed. Redundancy Analysis also indicated 18 key macroinvertebrate taxa in study streams responding to location within stream, habitat, and water quality. Of those 18 taxa shredders, collectors, and clingers were most frequently impacted. Improved understanding of the spatial scale of coal-mining influences on headwater stream characteristics will help inform bioassessment protocols to most accurately assess stream condition, and inform remediation efforts within the central Appalachian region and in other salinized stream systems.ETDenIn Copyrightsurface-coal miningsalinitybenthic macroinvertebratesspatial trendsspecific conductancewater qualityThesis