PW08 Aquatic Ecotoxicology II
Exhibit Hall
8:00 AM - Wednesday
(PW123) The toxicity of photomodified polycyclic aromatic hydrocarbons and dibenzothiophene congeners to Japanese medaka embryos.
Farwell, A.J.1, Croft, M.1, Bal, P.1, Dixon, D.G1, 1 Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
ABSTRACT- Alkylated polycyclic aromatic hydrocarbons (alkyl-PAHs) are naturally occurring compounds found in process-affected water following the extraction of bitumen mined from the Athabasca oil sands in northern Alberta, Canada. Previous studies have shown that the base-neutral hydrocarbon fraction of process-affected water (rich in alkyl-PAHs) significantly increased the frequency and severity of blue sac disease (BSD) symptoms, while reducing larval fork length at hatch in Japanese medaka (Oryzias latipes) 18 day early-life stage bioassays. The C2 - substituted dibenzothiophenes (DBTs) were found to be the most common hydrocarbons of the parent and methylated USEPA PAH priority pollutants (16) measured in the extract. The oil sands PAH extract, dibenzothiophene and dimethylated dibenzothiophene were exposed to simulated solar radiation (SSR) to determine the effects of UV exposure on the toxicity of a complex PAH extract and individual constituents known to be elevated in oil sands material. The Japanese medaka (Oryzias latipes) 18 day early-life stage bioassay protocol was modified from previous studies in order to accommodate testing for the changes in toxicity due to photomodification and photosensitization. The measurment endpoints including hatch success, hatch length, time to hatch and evidence of BSD were used to evaluate changes in toxicity. The oil sands PAH extract, exposed to simulated solar radiation (SSR) for 1 and 4 days, showed decreased toxicity to Japanese medaka embryos relative to the non-photomodified extract. With 4 day SSR exposure, there were no significant changes in hatch length or BSD symptoms whereas there was slight increase in time to hatch. Changes in toxicity associated with the photomodification and photosensitization of the PAH extract and dibenzothiophene congeners will be discussed in terms of the implications of PAH-UV exposure in reclaimed and natural aquatic environments in the region of the Athabasca oil sands deposit.
Key words: modifying factor, PAH toxicity, UV, japanese medaka