| The Canadian Boreal forest is rich with natural resources that humans depend on; one resource is oil in the form of oil sand. Mining companies have disturbed over 767 km2 of Boreal forest to reach surface-mineable oil sand in Alberta, Canada. After mining, companies reclaim these disturbed landscapes to support a chosen use-regime (e.g., wildlife habitat and recreation). Wetland reclamation is important since the Boreal forest is naturally rich in waterbodies. Companies have reclaimed areas and constructed experimental wetlands using by-products of oil sands processes, oil sands process-affected materials (OSPM), to test whether these materials can be used safely in reclamation projects. Researchers found that wetlands containing OSPM are toxic to aquatic organisms, including fish, macroinvertebrates, and amphibians. OSPM contains high concentrations of toxicants, including naphthenic acids, polycyclic aromatic hydrocarbons, metals, and salts that have been tied to lethal and sublethal effects on aquatic organisms. For my dissertation, I coauthored a literature review on the ecotoxicological effects of oil sands operations on aquatic organisms and independently conducted three experiments using native amphibians as bioindicators. Results from these experiments are as follows: 1) Wood frog and Boreal chorus frog tadpoles raised in oil sands wetlands experienced higher mortality than those in reference wetlands. Body condition was similar between oil sands and reference wetlands. Toxicity of oil sands wetlands is likely from sediment that can act as a reservoir for contaminants, and thus, a potential toxicant source for aquatic life; 2) In a laboratory study, wood frog tadpoles experienced higher mortality, had lower body condition indices, and spent less time active when exposed to sediment from oil sands wetlands than tadpoles without access to oil sands sediment and with or without access to sediment from reference wetlands; 3) Nickel at concentrations up to 5.1 mg/L was not lethal to wood frog tadpoles. However, Ni did accumulate in the tissue of tadpoles and had sublethal effects---nonlethal changes to an organism that can affect the population---on body condition, food consumption, and chemosensory function. Thus, it is unlikely that Ni is the singular cause of tadpole mortality in oil sands wetlands. Instead, mortality and sublethal effects of oil sands wetlands are likely due to a mixture of toxicants released from sediment. In these studies, oil sands wetlands did not effectively support native amphibians through larval development like reference wetlands. In order for reclaimed oil sands wetlands to support native flora and fauna, future research should focus on contaminants in oil sands wetland sediment, how these contaminants are entering these aquatic systems, and how to prevent further contamination. |
