Salinity as a limiting factor for biological condition in mining-influenced central appalachian headwater streams

Recent studies have found that Appalachian coal mining causes increased surface water salinity, and that benthic macroinvertebrate communities in salinized mining-influenced streams differ from communities in streams draining unmined areas. Understanding the role of salinity in shaping these communities is challenging because such streams are often influenced by a variety of stressors in addition to salinity. We characterized associations of salinity with biotic condition while isolating salinity from other stressors through rigorous site selection. We used a multimetric index of biotic condition to characterize benthic macroinvertebrate communities in headwater streams in the Central Appalachian Ecoregion of Virginia across a gradient of sulfate-dominated salinity. We found strong negative seasonal correlations between biotic condition and three salinity measures (specific conductance, total dissolved solids, and SO₄^2- concentration). We found no evidence to suggest stressors other than salinity as significant influences on biotic condition in these streams. Our results confirm negative associations of salinity with benthic macroinvertebrate community condition, as observed in other studies. Thus, our findings demonstrate that elevated salinity is an important limiting factor for biological condition in Central Appalachian headwater streams.