T3 PM Aquatic Ecotoxicology (Part 2)
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in Ballroom 3

(MUS-1117-833109) Selenium toxicosis in northern pike collected along a gradient of uranium milling effluent.

Muscatello, J^{1, 2}, Janz, D^{1, 2}, ¹ Toxicology Centre, Saskatoon, Saskatchewan, CANADA² Western College of Veterinary Medicine, Biomedical Sciences, Saskatoon, Saskatchewan, CANADA

ABSTRACT- Uranium mining in northern Saskatchewan, Canada are among the most productive uranium mines, generating 30% of the world′s uranium output. Elevated concentrations of selenium have been reported in water, sediments and fish tissues downstream of certain uranium mining and milling operations, as a consequence of uranium ore extractions, dewatering and milling. Most of the cases of selenium toxicosis in native fish populations have been reported for warm-water fish. Consequently, the applicability of guidelines and indices developed from warm-water systems to cold-water fishes, such as those in northern Saskatchewan, is controversial. The objective of the present study was to determine potential selenium toxicosis in early life stages of a native fish species, northern pike (Esox lucius) exposed to uranium milling effluent at Key Lake uranium mine. In Spring 2004, spawning northern pike were collected from a reference site and an exposure site 10 km downstream of uranium milling effluent discharge. Eggs and milt were stripped from adult female and male northern pike, fertilized in the field, and immediately transported to the University of Saskatchewan. A two-way ANOVA design was employed with embryos originating from reference and exposure sites incubated in both reference and exposure water. Deformity analysis (edema, craniofacial, skeletal, and fin deformities) showed that northern pike fry originating from the exposure site (mean egg selenium concentration 31.28 g/g dry weight) exhibited a significantly higher incidence of deformities compared to those originating from the reference site (mean egg selenium concentration 2.97 g/g dry weight). Furthermore, there were significant positive linear relationships between egg selenium concentrations and the frequencies of deformities observed in northern pike fry, as well as between egg and muscle selenium concentrations in adult female pike. Further fish collections will be conducted in Spring 2005 to increase sample sizes, sample additional sites, and confirm the results found in 2004. To date, our results suggest that maternal transfer of selenium to eggs is the causative factor for the increased frequency of deformities found in northern pike fry at this uranium milling operation.

Key words: Selenium, Deformities, Uranium mining, Northern pike