Influence of Water-Quality and Habitat Gradients on Macroinvertebrate Community Composition in Salinized Mining-Influenced Headwaters

Surface-coal mining in central Appalachia often results in salinization of headwater streams and alterations of habitat for aquatic biota. Responses in macroinvertebrate community composition across streams that vary in specific conductance (SC) and habitat have been documented. Headwater streams can also exhibit within-stream spatial variation in SC and habitat, frequently via dilution of mining-effluent, alterations in sedimentation, and altered stream channel morphology with distance downstream from mined areas. However, the extent to which coal-mining alters downstream patterns in water quality, habitat, and macroinvertebrate communities is largely unknown. This study aims to determine macroinvertebrate community responses to water-quality gradients and habitat characteristics within six Appalachian headwater streams (four mining-impacted, two reference). Streams and tributaries were sampled for macroinvertebrates, habitat characteristics, and water quality in fall 2021 and spring 2022 at six to nine locations per stream over a range of 1.5 – 3 km. Preliminary results suggest that although SC and large cobbles-to-fines ratios remain the primary drivers of community composition among streams, within-stream gradients vary independently and therefore are associated with unique responses in macroinvertebrate communities. Compared to larger-order systems, headwater gradients can increase water-quality and habitat heterogeneity for aquatic insect communities. Regression analysis, Bray-Curtis Similarity, constrained ordinations, and variation partitioning will be utilized to further examine the drivers of this heterogeneity and their influence on macroinvertebrate bioassessment metrics. Improved understanding of spatial scales and macroinvertebrate community response will help aid effective restoration, recolonization of biota, and ecological function of headwaters in the central Appalachian region and in other salinized stream systems.