Macroinvertebrate communities respond to spatial patterns of water quality and habitat within mining-influenced headwater streams of central Appalachia.

Surface coal mining in central Appalachia (USA) often results in salinization of headwater streams, with documented loss of several macroinvertebrate taxa and changes in community metrics across streams that vary in specific conductance (SC). However, the extent to which this salinization alters within-stream patterns in water chemistry and macroinvertebrate communities in these headwater streams is largely unknown. Here, we aimed to examine macroinvertebrate community responses to physical and chemical gradients within six Appalachian headwater streams (four salinized and two reference). We assessed benthic macroinvertebrates, habitat attributes, and water chemistry in two seasons at six to nine locations per stream over a range of 1.5-2.8 km. Commonly used community composition metrics exhibited within-stream variability in all streams, highlighting potential shortcomings of stream assessments commonly conducted via one sampling location. As expected, these metrics also showed correlations with SC at within-stream scales, particularly in streams with larger SC gradients. Expanded analyses highlighted additional drivers of community composition, including dissolved nutrients, hardness, streambed slope, and/or substrate. Further, taxa responding to within-stream gradients in each stream differed, which we attribute to unique environmental gradients among streams. Improved understanding of how salinization affects within-stream patterns in relation to additional stream attributes in headwater systems will help inform bioassessment protocols to more accurately assess stream condition and inform remediation efforts within the central Appalachian region and in other salinized systems.