@article{buchwalter_scheibener_chou_soucek_elphick_2019, title={Are sulfate effects in the mayfly Neocloeon triangulifer driven by the cost of ion regulation?}, volume={374}, ISSN={["1471-2970"]}, DOI={10.1098/rstb.2018.0013}, abstractNote={
            Elevated major ion concentrations in streams are commonly observed as a consequence of resource extraction, de-icing and other anthropogenic activities. Ecologists report biodiversity losses associated with increasing salinity, with mayflies typically being highly responsive to increases of different major ions. In this study, we evaluated the performance of the mayfly
            Neocloeon triangulifer
            reared for its entire larval phase in a gradient of sulfate concentrations. Two natural waters were amended with SO
            4
            as a blend of CaSO
            4
            and MgSO
            4
            and exposures ranged from 5 to 1500 mg l
            –1
            SO
            4.
            Survival (per cent successful emergence to the subimago stage) was significantly reduced at the highest SO
            4
            concentration in both waters, while development was significantly delayed at 667 mg l
            −1
            SO
            4
            . Final sub-adult body weights were consistent across treatments, except at the highest treatment concentration. Despite evidence for sulfate uptake rates increasing with exposure concentrations and not being saturated at even extremely high SO
            4
            concentrations, total body sulfur changed little in subimagos. Together, these results suggest that elevated SO
            4
            imposes an energetic demand associated with maintaining homeostasis that is manifested primarily as reduced growth rates and associated developmental delays. We identified two genes related to sulfate transport in
            N. triangulifer
            .
          }, number={1764}, journal={PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES}, author={Buchwalter, David and Scheibener, Shane and Chou, Hsuan and Soucek, David and Elphick, James}, year={2019}, month={Jan} }
 @article{scheibener_rivera_hesterberg_duckworth_buchwalter_2017, title={Periphyton uptake and trophic transfer of coal fly-ash-derived trace elements}, volume={36}, ISSN={["1552-8618"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85024902922&partnerID=MN8TOARS}, DOI={10.1002/etc.3864}, abstractNote={Abstract}, number={11}, journal={ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY}, author={Scheibener, Shane A. and Rivera, Nelson A. and Hesterberg, Dean and Duckworth, Owen W. and Buchwalter, David B.}, year={2017}, month={Nov}, pages={2991–2996} }
 @article{scheibener_conley_buchwalter_2017, title={Sulfate transport kinetics and toxicity are modulated by sodium in aquatic insects}, volume={190}, ISSN={["1879-1514"]}, DOI={10.1016/j.aquatox.2017.06.027}, abstractNote={The salinization of freshwater ecosystems is emerging as a major ecological issue. Several anthropogenic causes of salinization (e.g. surface coal mining, hydro-fracking, road de-icing, irrigation of arid lands, etc.) are associated with biodiversity losses in freshwater ecosystems. Because insects tend to dominate freshwater ecology, it is important that we develop a better understanding of how and why different species respond to salinity matrices dominated by different major ions. This study builds upon previous work demonstrating that major ion toxicity to the mayfly Neocloeon triangulifer was apparently due to the ionic composition of water rather than specific conductance. Synthetic waters with low Ca:Mg ratios and high SO4:Na ratios produced toxicity, whereas waters with higher Ca:Mg ratios and lower SO4:Na ratios were not toxic to mayflies at comparable conductivities. Here we used a radiotracer approach to show that Mg did not competitively exclude Ca uptake at environmentally realistic ratios in 4 aquatic insect species. We characterized SO4 uptake kinetics in 5 mayflies and assessed the influence of different ions on SO4 uptake. Dual label experiments show an inverse relationship between SO4 and Na transport rates as SO4 was held constant and Na was increased, suggesting that Na (and not Cl or HCO3) is antagonistic to SO4 transport. Based on this observation, we tested the hypothesis that increasing Na would protect against SO4 induced toxicity in a Na-dependent manner. Increasing Na from 0.7 to 10.9 mM improved 96-h survivorship associated with 20.8 mM SO4 from 44% to 73% in a concentration dependent manner. However, when Na reached 21.8 mM, survivorship decreased to 16%, suggesting that other interactive effects of major ions caused toxicity under those conditions. Thus, the combination of elevated sulfate and low sodium commonly observed in streams affected by mountaintop coal mining has the potential to cause toxicity in sensitive aquatic insects. Overall, it is important that we develop a better understanding of major ion toxicity to effectively mitigate and protect freshwater biodiversity from salinization.}, journal={AQUATIC TOXICOLOGY}, author={Scheibener, Shane and Conley, Justin M. and Buchwalter, David}, year={2017}, month={Sep}, pages={62–69} }
 @article{scheibener_richardi_buchwalter_2016, title={Comparative sodium transport patterns provide clues for understanding salinity and metal responses in aquatic insects}, volume={171}, ISSN={["1879-1514"]}, DOI={10.1016/j.aquatox.2015.12.006}, abstractNote={The importance of insects in freshwater ecosystems has led to their extensive use in ecological monitoring programs. As freshwater systems are increasingly challenged by salinization and metal contamination, it is important to understand fundamental aspects of aquatic insect physiology (e.g., osmoregulatory processes) that contribute to insect responses to these stressors. Here we compared the uptake dynamics of Na as NaCl, NaHCO3 and Na2SO4 in the caddisfly Hydropsyche betteni across a range of Na concentrations (0.06-15.22 mM) encompassing the vast majority of North American freshwater ecosystems. Sulfate as the major anion resulted in decreased Na uptake rates relative to the chloride and bicarbonate salts. A comparison of Na (as NaHCO3) turnover rates in the caddisfly Hydropsyche sparna and the mayfly Maccaffertium sp. revealed different patterns in the 2 species. Both species appeared to tightly regulate their whole body sodium concentrations (at ∼47±1.8 μmol/g wet wt) across a range of Na concentrations (0.06-15.22 mM) over 7 days. However, at the highest Na concentration (15.22 mM), Na uptake rates in H. sparna (419.1 μM Na g(-1) hr(-1) wet wt) appeared close to saturation while Na uptake rates in Maccaffertium sp. were considerably faster (715 g μM Na g(-1) hr(-1) wet wt) and appeared to not be close to saturation. Na efflux studies in H. sparna revealed that loss rates are commensurate with uptake rates and are responsive to changes in water Na concentrations. A comparison of Na uptake rates (at 0.57 mM Na) across 9 species representing 4 major orders (Ephemeroptera, Plecoptera, Trichoptera and Diptera) demonstrated profound physiological differences across species after accounting for the influence of body weight. Faster Na uptake rates were associated with species described as being sensitive to salinization in field studies. The metals silver (Ag) and copper (Cu), known to be antagonistic to Na uptake in other aquatic taxa did not generally exhibit this effect in aquatic insects. Ag only reduced Na uptake at extremely high concentrations, while Cu generally stimulated Na uptake in aquatic insects, rather than suppress it. These results help explain the lack of insect responses to dissolved metal exposures in traditional toxicity testing and highlight the need to better understand fundamental physiological processes in this ecologically important faunal group.}, journal={AQUATIC TOXICOLOGY}, author={Scheibener, S. A. and Richardi, V. S. and Buchwalter, D. B.}, year={2016}, month={Feb}, pages={20–29} }