The effects of oil sands wetlands on wood frogs (Rana sylvatica)

Abstract

Extraction of crude oil from oil sand produces solid (sand) and liquid (water with suspended fine particles) tailings materials, called oil sands process-affected materials (OSPM). These waste materials are stored on the mine site due to a “zero discharge” policy and must be reclaimed when operations end. The liquid tailings materials are known to contain naphthenic acids and polycyclic aromatic hydrocarbons and have high pH and salinity. One method of reclamation is the “wet landscape” approach, which involves using oil sands tailings materials to form wetlands that would mimic natural wetland ecological function. This study investigated the effects of wetlands formed with oil sands tailings materials on the survival and growth of wood frog (Rana sylvatica) larvae. In spring 2007, in-situ caging studies were completed in 14 wetlands that were of four different classes; young or old, reference or reclaimed. Tadpole survival was different between types of wetlands, with young tailings-affected wetlands (≤7 years old) having 41.5%, 62.6%, and 54.7% higher tadpole mortality than old tailings-affected (>7 years old), young reference, and old reference wetlands, respectively. Since old wetlands created from OSPM showed effects on tadpoles similar to those of reference wetlands, which had markedly lower toxicity than young tailings-affected wetlands, we provide evidence that wetlands, at least 7 years old, can sustain amphibian life.

Keywords:

• oil sands
• wood frog
• toxicology
• bioindicator

Acknowledgments

Funding for this research was generously provided by Discovery and Collaborative Research and Development Grants from the Natural Science and Engineering Research Council of Canada (JS-JC), as well as our industry partners, Syncrude Canada Ltd., Suncor Energy Inc., Albian Sands Energy Inc., Canadian Natural Resources Ltd., Imperial Oil Ltd., Petro-Canada, and Total E and P Ltd. We would also like to thank the countless number of people who helped with laboratory and field work.