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Uptake of Sulfate from Ambient Water by Freshwater Animals
Citation:
Griffith, M., J. Lazorchak, AND H. Haring. Uptake of Sulfate from Ambient Water by Freshwater Animals. WATER. MDPI, Basel, Switzerland, 12(5):1496, (2020). https://doi.org/10.3390/w12051496
Impact/Purpose:
EPA has developed water quality benchmarks and is developing ambient water quality criteria for elevated ion concentrations in freshwaters using specific conductivity, which is a measure of total ion concentrations, as the chemical measurement endpoint to protect aquatic life. However, there is still some uncertainty on how different ions contribute to the adverse effects associated with elevated ionic strength or salinity in freshwaters, and some states and regulated entities have suggested that concentrations of specific ions be the targets of chemical monitoring and ambient water quality criteria. One of these specific ions is sulfate, which is a known to be elevated in waters effected by mining, which exposes sulfide minerals, such as pyrite associated with coal mining and other metal sulfides associated with hardrock metal mining. To support decisions relating to the potential for adverse effects associated with individual major ions, sodium, potassium, calcium, magnesium, chloride, sulfate, and biocarbonate, a literature review of the ion physiology of four primary freshwater animal groups; fish, Crustacea, aquatic insects, and Mollusca; was conducted. This review found a data gap related to the regulatory physiology of sulfate. It appears that sulfate is relatively impermeant to the gill membranes of fish, but there are sulfate transporters in amphibian skin, which functions similarly to gill membranes in ion uptake by fish, Crustacea, and Mollusca or to anal papillae or chloride epithelia, which are involved in ion uptake in aquatic insects. This project has begun to fill some of these data gaps by conducting laboratory experiments with a model species from each of the freshwater animal groups, Crustacea (Procambarus clarkii), fish (Pimephales promelas), aquatic insects (Neocloeon triangulifer or Hexagenia bilineata), and unionid mussels (Lampsilis cardium or Utterbackia imbecillis). The experiments will measure the uptake of SO4 2- from ambient waters and the effect of ambient SO4 2- concentrations on its uptake and possible toxicity. If 6 uptake is detected, the next step would be to attempt to identify protein transporters for SO4 2- associated with ionocytes in these animals by genomic comparisons to families of known SO4 2- transporters that have been identified in mammals or other animals.
Description:
To better understand how the sulfate (SO42−) anion may contribute to the adverse effects associated with elevated ionic strength or salinity in freshwaters, we measured the uptake and efflux of SO42− in four freshwater species: the fathead minnow (Pimephales promelas, Teleostei: Cyprinidae), paper pondshell (Utterbackia imbecillis, Bivalvia: Unionidae), red swamp crayfish (Procambarus clarkii, Crustacea: Cambaridae), and two-lined mayfly (Hexagenia bilineata, Insecta: Ephemeridae). Using δ(34S/32S) stable isotope ratios and the concentrations of S and SO42−, we measured the SO42− influx rate (Jin), net flux (Jnet), and efflux rate (Jout) during a 24 h exposure period. For all four species, the means of Jin for SO42− were positive, and Jin was significantly greater than 0 at both target SO42− concentrations in the fish and mollusk and at the lower SO42− concentration in the crayfish. The means of Jout and Jnet were much more variable than those for Jin, but several species by target SO42− concentration combinations for Jout and Jnet, were negative, which suggests the net excretion of SO42− by the animals. The results of our experiments suggest a greater regulation of SO42− in freshwater animals than has been previously reported.
