| DISSOLVED OXYGEN TOLERANCES FOR EGG AND LARVAL STAGES OF RAZORBACK SUCKER |
| STOLBERG, J.R., U.S. Bureau of Reclamation, Boulder City, NV, United States, 89005, JStolberg@usbr.gov; Horn, M.J., U.S. Bureau of Reclamation, Denver, CO, United States, 80225, MHorn@usbr.gov |
| Laboratory experiments were conducted to compare hatching success, survival, and growth of razorback sucker (Xyrauchen texanus) embryos and larvae exposed to dissolved oxygen concentrations of 1 - 8 mg/liter at temperatures of 18 - 22° C. Total mortality of embryos occurred in 72 hours at 1 mg/liter (0.78 ± 0.36), and in 120 hours at 2 mg/liter (2.12 ± 0.05). Hatch success for the remaining treatments ranged from 27 - 61%. Larval response was evaluated in 72 hour tests and resulted in near total mortality at 1 mg/L (1.39 ± 0.5) and mortalities of 43% and 5% at 2 mg/L (2.14 ± 0.3) and 3 mg/L (2.92 ± 0.3) respectively. Less than 1% mortality was observed for larval fish exposed to dissolved oxygen concentrations equal to or greater than 4mg/L (3.95 ± 0.3). Comparative growth of larval razorback was also evaluated for 20 day-old fish exposed to dissolved oxygen concentrations of 3 - 8 mg/L for 20 days. No significant difference in mean growth was observed. |
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