PW08 Aquatic Ecotoxicology II
Exhibit Hall
8:00 AM - Wednesday
(PW134) Chronic toxicity of NaHCO3 to fathead minnows in water simulating the Tongue River, Montana, USA.
Morris, B1, 2, Farag, A2, Meyer, J1, 1 University of Wyoming, Laramie, WY, USA2 U.S. Geological Survey, Jackson, WY, USA
ABSTRACT- In the Tongue River Basin of Montana, USA, the extraction of natural gas from coal seams (commonly referred to as coalbed natural gas -- CBNG) produces large quantities of groundwater as a by-product. Some CBNG product waters in this region contain high concentrations of inorganic salts (e.g., sodium bicarbonate) that can adversely affect aquatic life. The objectives of this study were to (1) determine the chronic toxicity of NaHCO3 for the egg/larval stage of fathead minnows (FHM; Pimephales promelas) in water similar to the Tongue River, and (2) determine the sublethal effects of NaHCO3 on growth, ionoregulation, and tissue structure in key organs. We conducted two flow-through experiments beginning with freshly fertilized FHM eggs in concentrations ranging from 6 to 17 and 3.5 to 7.5 mM Na (added as NaHCO3), respectively. Both experiments were terminated at 60 d post hatch (a 65-d total exposure). Percentage hatch of the eggs at 17 and 7.5 mM Na was significantly lower than the controls during Experiments 1 and 2, respectively. We also observed a 15% decrease in survival during the swimup stage (∼5-8 d post hatch) during both experiments. For Experiment 1, survival decreased significantly at all concentrations ≥9.5 mM Na. Survival did not decrease significantly in Experiment 2 because it was conducted at lower NaHCO3 concentrations to better determine sublethal effects. Lengths and weights recorded for individual fish did not decrease significantly in either experiment. Whole-body ion concentrations, Na/K ATPase activity, and histology are being analyzed for other sublethal effects.
Key words: growth, fathead minnow, sodium bicarbonate, survival