Effects of ammonium sulfate on growth of larval Northwestern salamanders, red-legged and Pacific treefrog tadpoles, and juvenile fathead minnows

Flow-through tests were conducted to determine the effects of ammonium sulfate on the growth of three native amphibian species and one introduced fish species in the Willamette Valley of western Oregon. The amphibians were the Northwestern salamander Ambystoma gracile, the Pacific treefrog Pseudacris regilla, and the red-legged frog Rana aurora, and the fish was the fathead minnow Pimephales promelas. Ammonium nitrogen concentrations ranged from 0 to more than 200 mg/l. Results showed that P. promelas was the most tolerant of the four species, although six-week-old fish had the same sensitivity as salamanders and red-legged frogs. The lowest-observed-effect concentrations of ammonium N to five-week-old A. gracile, six-week-old P. regilla, nine-week-old P. regilla, four-week-old R. aurora, six-week-old P. promelas, and nine-week-old P. promelas were 126.5, 37.0, 52.5, 134.0, 118.0, and 227.0 mg/l, respectively.