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2F - Site Specific Testing (MOP/106) Toxicity of uranium to early life-stage lake trout (Salvelinus namaycush). Liber, Karsten1, Stoughton, Sarah1, Janz, David1, Moulding, Tim2, 1 Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada2 Environment Section, Saskatchewan Environment, La Ronge, SK, Canada ABSTRACT- The northern part of the Canadian province of Saskatchewan is home to some of the top-producing uranium mines in the world. The higher uranium concentrations found in water downstream from mining and milling operations indicate that these are important areas of potential impact of uranium on aquatic organisms. Despite the fact that uranium mining has occurred in Saskatchewan since the 1960s, very limited data exist on the chronic toxicity of uranium to aquatic organisms. Water quality objectives for the protection of aquatic life do not yet exist, largely due to the absence of data required for the derivation of such values. Data from life-cycle or partial life-cycle toxicity studies are particularly needed for fish to help develop a sound water quality objective for uranium levels in northern Saskatchewan waters. This work evaluated the chronic toxicity of uranium to early life-stages (e.g., embryos, alevins, fry) of lake trout (Salvelinus namaycush), a common and culturally/economically important fish species in northern Saskatchewan. Fertilized eggs were exposed to one of five uranium concentrations (ranging from 0.05 to 31 mg/L) starting on the day of fertilization and ending 30 days after swim-up (approx. 4 month exposure period). Exposure solutions were replaced weekly (static renewal) and uranium concentrations (which stayed relatively constant) and water quality measured routinely. Uranium speciation in the test solutions was modeled using MINTEQA2. Results to date indicate that the embryo phase is very tolerant to uranium exposure, with toxicity largely expressed during the hatching and swim-up phases. Data will be presented on the effects of uranium on survival at different life stages, alevin and fry growth, general fish behaviour, and biochemical endpoints such as whole body triglycerides, RNA/DNA ratio, and total proteins. Key words: lake trout, uranium, early life-stage tests, water quality objectives |
