Uptake of Sulfate from Ambient Water by Freshwater Animals.
To better understand how the sulfate (SO4 2-) anion may contribute to the adverse effects associated with elevated ionic strength or salinity in freshwaters, we measured the uptake and efflux of SO4 2- 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(  S/  S) stable isotope ratios and the concentrations of S and SO4 2-, we measured the SO4 2- influx rate (J  ), net flux (J  ), and efflux rate (Jout) during a 24 h exposure period. For all four species, the means of J  for SO4 2- were positive, and J  was significantly greater than 0 at both target SO4 2- concentrations in the fish and mollusk and at the lower SO4 2- concentration in the crayfish. The means of J  and J  were much more variable than those for J  , but several species by target SO4 2- concentration combinations for J  and J  , were negative, which suggests the net excretion of SO4 2- by the animals. The results of our experiments suggest a greater regulation of SO4 2- in freshwater animals than has been previously reported.
['Griffith|Michael B|MB|0000-0002-0888-1725', 'Lazorchak|James M|JM|0000-0002-7354-7571', 'Haring|Herman|H|']
uptake sulfate freshwater efflux fish invertebrates