Sublethal effects of aged oil sands-affected water on white sucker (Catostomus commersonii).

To investigate impacts of proposed oil sands aquatic reclamation techniques on benthic fish, white sucker (Catostomus commersonii Lacépède, 1803) were stocked in 2 experimental ponds-Demonstration Pond, containing aged fine tailings capped with fresh water, consistent with proposed end-pit lake designs, and South Bison Pond, containing aged unextracted oil sands material-to examine the effects of unmodified hydrocarbons. White sucker were stocked from a nearby reservoir at both sites in May 2010 and sampled 4 mo later to measure indicators of energy storage and utilization. Comparisons were then made with the source population and 2 reference lakes in the region. After exposure to aged tailings, white sucker had smaller testes and ovaries and reduced growth compared with the source population. Fish introduced to aged unextracted oil sands material showed an increase in growth over the same period. Limited available energy, endocrine disruption, and chronic stress likely contributed to the effects observed, corresponding to elevated concentrations of naphthenic acids, aromatic compounds in bile, and increased CYP1A activity. Because of the chemical and biological complexity of these systems, direct cause-effect relationships could not be identified; however, effects were associated with naphthenic acids, polycyclic aromatic hydrocarbons, ammonia, and high pH. Impacts on growth have not been previously observed in pelagic fishes examined in these systems, and may be related to differences in sediment interaction.

Reproductive development of yellow perch (Perca flavescens) exposed to oil sands-affected waters.

In similar experiments conducted in 1996 and 2009, yellow perch (Perca flavescens) were stocked into two experimental systems: a demonstration lake where oil sands fine tailings were capped with natural water and a lake in a watershed containing bitumen-bearing sodic clays. In both experiments, yellow perch were captured in May from a nearby reservoir and released into the experimental ponds. Perch were recaptured in the experimental systems, the source lake, and two reference lakes in late September and lethally sampled to examine reproductive parameters. In the 1996 experiment, gonad size and steroid hormones were not affected in either pond environment. In the 2009 experiment, male perch in the water-capped tailings pond showed a significant reduction in the testicular development and reductions in circulating testosterone and 11-ketotestosterone, while no reductions were seen in the second experimental pond. No changes were observed in ovarian size or circulating steroid levels in female perch. In the pond containing tailings, the release of water from underlying tailings caused approximately a twofold increase in salinity, alkalinity, and naphthenic acids, and a pH increase from 8.4 to 9.4 over the 13-year period of the study. In the pond influenced by unextracted oil sands materials, total dissolved solids, major ions, and pH did not change substantially. However, naphthenic acids in this system dropped more than twofold post-watershed reclamation. Because the selective reproductive effect observed in male perch in the experimental end-pit lake were accompanied by increases in naphthenic acids, alkalinity, and pH, a specific cause cannot be determined. The present study adds to the evidence, suggesting the presence of endocrine-disrupting substances in oil sands.