MP13 Aquatic Ecotoxicology
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(KAV-1117-833387) Reproductive impairment observed in fish exposed to oil sands tailings.

Kavanagh, R¹, Van Der Kraak, G¹, ¹ Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada

ABSTRACT- Approximately 20 % of the oil that Canada produces comes from Alberta's oil sands. As a result of the Clarke hot water extraction method, 4 m³ of fluid tailings are produced for each m³ of oil sand processed. Over 3 x 10⁸ m³ of fluid tailings are currently being stored in settling ponds. Developers plan to eventually transfer these tailings to mined-out pits and cap them with a layer of clean water and an aquatic ecosystem is then expected to be established in these end pit lakes. Previous work suggests that the oil sand constituents that are present in these lakes may alter the reproductive physiology of fish. In order to determine if fluid tailings would impair reproduction, a 21 day fathead minnow reproduction assay was conducted at Syncrude Canada Ltd. Fathead minnows were held in Gregoire Lake water (reference site) for 14 days to gather baseline data on fecundity, fertility, and hatching success. Fathead minnows were then held in water from different tailings ponds and in Gregoire Lake water for 21 days and fecundity, fertility, and hatching success were monitored. A total cessation of spawning was observed in fathead minnows that had been held in tailings pond water. Female fathead minnows also had significantly reduced GSIs and male fish had tubercles that were reduced both in size and number. Naphthenic acids, which are natural constituents of oil sands, are one of the contaminants suspected of being responsible for the reproductive impairment observed in fathead minnows. In vitro studies provide some support for this theory as fish testes stimulated with hCG and incubated with naphthenic acid extract (10 mg/l)showed a significant reduction in testosterone levels compared to controls. Collectively these studies show that oil sands tailings have the potential to affect the reproductive physiology of fish.

Key words: endocrine disruption, naphthenic acids, fish, oil sands