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Influx and efflux of sulfate from ambient water in freshwater animals
Citation:
Griffith, M., Jim Lazorchak, AND H. Haring. Influx and efflux of sulfate from ambient water in freshwater animals. 2021 Society for Freshwater Science Annual Meeting, Virtual, May 23 - 27, 2021.
Impact/Purpose:
Relatively little is known about the ionoregulation of sulfate in freshwaters. To understand how the sulfate anion may contribute to adverse effects associated to elevated ionic strength in freshwater, we conducted a series of experiments to measure the uptake and efflux of sulfate in representatives of 4 freshwater groups. If there is no uptake of sulfate from ambient waters, increasing water concentrations of sulfate would not increase internal sulfate concentrations and directly affect organismal sulfate concentations and ionic balances. Effects would only occur due to osmotic imbalances. However, we did observe sulfate uptake and excretion in all 4 species, suggesting the presence cellular transporters for sulfate. This research is intended to assist OW, OST in decisions relating to the development of ambient water quality criteria for individual ions, such as sulfate.
Description:
To investigate how the sulfate anion (SO42-) may be related to the adverse effects associated with elevated ionic concentrations in freshwaters, we measured influx and efflux of SO42- in four freshwater groups represented by a fish (Pimephales promelas) and three invertebrates: a unionid Utterbackia imbecillis, a crayfish Procambarus clarkii, and a mayfly, Hexagenia bilineata. Using stable isotope ratios, δ(34S/32S), and S and SO42- concentrations, we measured the SO42− influx rate, net flux, and efflux rate during an exposure of 24-hr from water with two concentrations of 34S-enriched NaSO4. The mean estimates of SO42− influx were positive for all four species, and SO42− influx was greater than 0 for both SO42− concentrations in the fish and mollusk and for the lower SO42- concentration in the crayfish. SO42− efflux and net flux estimates were much more variable than those for SO42− influx, but efflux and net flux were negative for some species by SO42- concentration combinations, which suggests net excretion of SO42- by the animals. These results suggest that uptake of SO42- from ambient waters can result in the adverse effects that have been identified with elevated SO42- in freshwaters.
