Stable carbon and nitrogen isotopes of tree swallows influenced by oil sands aquatic reclamation

This presentation reported on a study in which tree swallows (Tachycineta bicolor) were studied to evaluate reclamation strategies used by oil sand operators in Alberta. Wetland reclamation involves the transformation of tailings water and solids into functioning aquatic ecosystems. Naphthenic acids (NAs) and polycyclic aromatic compounds (PACs) in tailing/reclamation material are toxic constituents that pose concern for growth rate, reproductive function and immune function in tree swallows. Exposure to xenobiotics from these tailings-based sites was determined by increased detoxification enzyme (EROD) activity. The dietary exposure of tree swallows to oil sands constituents was determined through stable isotope analysis. Previous studies revealed trends of 13C depletion and 15N enrichment in benthic invertebrates from reclaimed wetlands on the oil sands. Since most food consumed by tree swallow nestlings is aquatic, the isotope signatures in tree swallows should provide evidence of exposure to oil sands constituents. Tree swallow feather and muscle tissues were examined in this study to determine if stable isotopes could be used to identify dietary contributions from oil sands reclamation sites versus reference sites containing no tailings materials.