Salinity as a Limiting Factor for Biological Condition in Mining‐Influenced Central Appalachian Headwater Streams

Abstract

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 SO42− 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.

Spatial and temporal relationships among watershed mining, water quality, and freshwater mussel status in an eastern USA river

“…Mining-related variables recorded with sufficient frequency to enable analysis (pH, SC, and TDS) were emphasized. Sulfate (SO 4 2 − ), bicarbonate (HCO 3 − ), calcium (Ca 2+ ), and magnesium (Mg 2+ ) are generally recognized as the predominant ions in nonacidic waters draining Appalachian surface mines (Pond et al, 2008;Pond et al, 2014;Orndorff et al, 2015;Timpano et al, 2015); hence, SO 4 2− , hardness and alkalinity were also included. Two additional variables (total nitrogen, total N; and chloride, Cl − ) that represent anthropogenic impacts more generally were also obtained and analyzed.…”

“…Yet, a number of studies have documented stressed biotic resources in the region's mining-influenced rivers and streams. Water salinity, measured as specific conductance (SC) and/or total dissolved solids (TDS), is often elevated in such streams (Bryant et al, 2002;Hartman et al, 2005;Merricks et al, 2007;Pond et al, 2008;Wood and Williams, 2013;Gangloff et al, 2015;Pond et al, 2014;Timpano et al, 2015), and recent research has linked elevated salinity with biotic impacts. Depressed richness of benthic macroinvertebrate communities often occurs in mining-influenced low-order streams with elevated SC (Green et al, 2000;Hartman et al, 2005;Pond et al, 2008;Cormier et al, 2013aCormier et al, , 2013bPond et al, 2014;Timpano et al, 2015).…”

“…Water salinity, measured as specific conductance (SC) and/or total dissolved solids (TDS), is often elevated in such streams (Bryant et al, 2002;Hartman et al, 2005;Merricks et al, 2007;Pond et al, 2008;Wood and Williams, 2013;Gangloff et al, 2015;Pond et al, 2014;Timpano et al, 2015), and recent research has linked elevated salinity with biotic impacts. Depressed richness of benthic macroinvertebrate communities often occurs in mining-influenced low-order streams with elevated SC (Green et al, 2000;Hartman et al, 2005;Pond et al, 2008;Cormier et al, 2013aCormier et al, , 2013bPond et al, 2014;Timpano et al, 2015). Recent studies have also found fish assemblage structure (Hitt and Chambers, 2014), salamander abundance (Wood and Williams, 2013) and richness (Muncy et al, 2014), and microbial community composition (Bier et al, 2015) to be altered in salinized mining-influenced streams; and freshwater mussel richness and densities to be depressed in salinized river segments .…”

Effects of environmentally relevant mixtures of major ions on a freshwater mussel

“…Mining-origin elevated stream salinity and associated alterations of aquatic communities have been documented throughout Appalachian USA (Bernhardt et al, 2012;Cormier et al, 2013;Evans et al, 2014;Griffith et al, 2012;Hitt and Chambers, 2014;Pond et al, 2008;Timpano et al, 2015). The dominant major ions in mining-influenced Appalachian waters are generally SO 4 2À , HCO 3 À , Ca 2þ , and Mg 2þ ; but K þ , Na þ , and Cl À can also become elevated (Cormier et al, 2013;Pond et al, 2008;Timpano et al, 2015). Increasing salinization of Appalachian streams and rivers is of concern because they often support exceptionally high biodiversity.…”

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

“…Overall, EPT dominated the drift, with Ephemeroptera comprising the most richness and abundance in larger tributaries, and Plecoptera often dominating richness and abundance in the smaller tributaries (but this varied by sample month). Since EPT (particularly mayfly richness and abundance) are typically reduced in mining-impacted streams throughout the region (e.g., Pond et al, 2008;Timpano et al, 2015), our finding has potential implications on the importance of intact tributaries to biodiversity and conservation of receiving streams (Pond et al, 2014). Daily export of EPT taxa was strongly related to catchment area and month while the opposite was found for EPT taxon concentrations where smaller steams produced higher monthly richness per volume of water.…”