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Effects of oil sands process-affected water and substrates on wood frog (Rana sylvatica) eggs and tadpoles



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An essential element of the reclamation strategy proposed by the oil sands mining industry in northern Alberta, Canada, includes the creation of wetlands for the bioremediation of mining waste materials. The mining process used to extract oil from these deposits results in the production of large volumes of process-affected water (OSPW) and sediments (OSPS), which must be incorporated into wetlands as a component of the reclaimed landscapes. Wood frogs (Rana sylvatica) are an abundant native species that might be expected to inhabit these reclaimed wetlands. The objective of this study was to determine potential detrimental effects of OSPW and OSPS on the growth and development of wood frogs. Several morphological (weight, length, condition factor) and biochemical (whole body tadpole thyroid hormone and triglyceride concentrations and metamorph hepatic glycogen concentration) endpoints were assessed in conjunction with hatchability and survivability of wood frog eggs and tadpoles exposed to process-affected materials (OSPM) under field and laboratory conditions. As part of this study, assay techniques were optimized to enable simultaneous measurement of whole body 3,5,3’-triiodothyronine (T3), thyroxine (T4) and triglyceride (TG) concentrations in wood frog tadpoles. These assays were used to monitor changes in T3, T4 and TG in wood frog tadpoles during development from hatching to metamorphosis (Gosner stages 19-46), to establish baseline levels for subsequent application of the assays to evaluate contaminant effects. The results indicated peak T3 and T4 concentrations occurred during metamorphic climax (Gosner stages 40-46) and prometamorphosis (Gosner stages 31-40), respectively. Maximal TG concentrations were also observed during prometamorphosis. These assays were further employed to assess body condition and development in wood frogs during a field study in 2005, and the following laboratory studies in 2006 and 2007. In summer 2005, 29 reclaimed and five unimpacted wetlands were monitored for use by native amphibians, and tadpoles and newly-metamorphosed wood frogs were collected from a subset of sites as a preliminary assessment of contaminant effects. Endpoints such as metamorph hepatic glycogen and whole body tadpole T3, T4 and triglyceride concentrations were compared among six impacted and three reference wetlands. The surveys indicated 60% of OSPW-impacted wetlands were used by breeding adult amphibians, while wood frog tadpoles and newly-metamorphosed frogs were observed in 37 and 30% of OSPW wetlands, respectively. In general, lower whole body tadpole T3 and triglyceride concentrations were observed in wood frogs from wetlands containing OSPM. In contrast, hepatic glycogen concentrations in newly-metamorphosed frogs and whole body tadpole T4 and T3/T4 concentrations were comparable among the reference and impacted wetlands. In addition, the differences observed in total body weight and length of tadpoles and newly-metamorphosed wood frogs among OSPM and reference sites were likely due to minor differences in developmental stages of the animals collected from the various wetlands, rather than any contaminant effect. In 2006 and 2007, wood frog eggs and tadpoles were exposed to several sources of OSPW and OSPS collected from reclaimed Suncor and Syncrude wetlands under controlled laboratory conditions. Hatchability was reduced in eggs exposed to water from only one of the OSPW sites, compared with the other process-affected ponds and the control water (P



Athabasca Oil sands, Wood Frogs, Oil sands process-affected water, Thyroid hormone, Oil sands process-affected substrates



Master of Science (M.Sc.)






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