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

(FAR-1117-816769) Phototoxicity of oil sands derived polycyclic aromatic hydrocarbons to Japanese medaka, Oryzias latipes.

Farwell, AJ¹, Nero, V¹, Croft, M¹, Rhodes, S¹, Dixon, DG¹, ¹ University of Waterloo, Waterloo, Ontario, Canada

ABSTRACT- Alkylated polycyclic aromatic hydrocarbons are present in natural and reclaimed aquatic environments in the region of the oil sands in northern Alberta, Canada. An oil-sands derived PAH extract, rich in alkylated PAHs, has been shown to induce significant lethal and sublethal responses using the Japanese medaka embryo-larval assay. While information on exposure and effects of oil sands PAHs is available, there is little information on the impact of modifying factors. This study focuses on the effect of solar radiation on oil-sands derived PAH extract toxicity. Japanese medaka embryo larval experiments were conducted to determine the toxicity of the photomodified PAH extract following 1 and 4 day exposures to simulated solar radiation (SSR). Next, to evaluate the combined toxic effects of photomodified and photosensitized products of the oil-sands PAH extract, Japanese medaka embryos were co-exposed to the PAH extract + SSR, and compared to exposures of a photomodified and non-photomodified PAH extract. Changes in toxicity were evaluated using the following measurement endpoints: mortality, hatch length, and evidence of BSD symptoms. A one day pre-exposure of the PAH extract was sufficient to reduce the toxic effects for all measurement endpoints compared to the non-photomodified extract. A four day pre-exposure of the PAH extract was required to further reduce the effect on hatch length which was the most sensitive endpoint. PAH + SSR (16h) co-exposure enhanced lethality and the sublethal effects on embryonic development (BSD symptoms) compared to the photomodified (16h) and non-photomodified PAH exposures. Reductions in hatch length for the PAH + SSR (16h) co-exposure and the non-photomodified PAH extract exposure were similar (LOEC, 11 g/l), whereas the photomodified extract had less of an effect on hatch length (LOEC, 44 g/l). The 2-fold increase in the toxic effects to embryonic development has implications for environmental risk assessment, monitoring and reclamation strategies.

Key words: alkylated polycyclic aromatic hydrocarbons, Japanese medaka, oil sands, UV