Failure of Hydra populations to develop tolerance, indicates absence of toxicity from a mining whole-effluent

摘要

The green hydra, Hydra viridissima, exists in water bodies on the Project Area of the Ranger Uranium Mine (RUM) in northern Australia, which contain concentrations of magnesium (Mg), higher than those reported to cause toxicity from the Environmental Research Institute of the Supervising Scientist (eriss) laboratory toxicity tests. McCullough (2006) reported a lowest-observed-effect-concentration (LOEC) for H. viridissima of 4.6 mg L~(-1) Mg, (present as MgSO_4), which represented a population growth rate decrease of approximately 30% relative to the control response. The same study found that toxicity was due to Mg and not SO_4. However, Corbett (1996) reported the presence of H. viridissima in water bodies on the RUM Project Area containing Mg concentrations above this LOEC, and theoretically high enough to severely impact population growth (i.e., 10-20 mg L~(-1)).