||Comparative Responses of Speckled Dace and Cutthroat Trout to Air-Supersaturated Water.
Nebeker, Alan V. ;
Hauck, A. Kent ;
Baker, Faye D. ;
Weitz, Stephen L. ;
||National Heart, Lung, and Blood Inst., Bethesda, MD.
Water pollution ;
Lethal dosage ;
Rhinichtys asculus ;
Salmo clarki ;
Water pollution effects(Animals) ;
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Speckled dace (Rhinichtys asculus) are more tolerant of air-supersaturated water than adult or juvenile cutthroat trout (Salmo clarki). Speckled dace were tested in concentrations from 110 to 142% saturation and had a 96-hour median lethal concentration (LC50) of 140%, a 7-day LC50 of 137% and 2-week LC50's of 129 and 131% saturation. The estimated mean threshold concentration, based on time to 50% death (TM50), was 123% saturation. The speckled dace also exhibited consistent external signs of gas bubble disease. Cutthroat trout were tested from 111 to 130% saturation and had 96-hour LC50's of 119 and 120% (adults) and 119 and 119% (juveniles) saturation. Estimated mean threshold concentrations (from TM50 values) were 117% (adults) and 114% (juveniles) saturation. Signs of gas bubble disease exhibited by the cutthroat trout were similar to those seen with other salmonids examined in earlier studies.