Carbon Dynamics, Food Web Structure, And Reclamation Strategies in Athabasca Oil Sands Wetlands (CFRAW)

Reconstructed wetlands will be a critical component of reclaimed landscapes in the Oil Sands Region. This project is a multi-year, multi-university initiative to identify the biological processes necessary to achieve functioning wetlands in boreal undisturbed and reconstructed wetlands. The objectives include (1) Assess several classes of wetlands differing in reclamation type, age, and organic base, (2) document how different types of biomass are incorporated into the food web as constructed wetlands age, (3) Determine how this influences community development and the ultimate productivity of fish and wildlife, and (4) determine whether wetlands built with peat amendments can be expected to maintain their productivity and become true peatlands.

Researchers examined 16 wetlands in the Athabasca oil sands region to evaluate ecological recovery in areas affected by oil sands process materials (OSPM). Wetlands were quickly colonized by plants and animals, but full recovery—especially in submergent plant diversity and food web structure—took 15–20 years in OSPM-affected sites. Water chemistry, particularly salinity and naphthenic acids in oil sands process water (OSPW), was a key factor limiting recovery and carbon production. Adding peat helped accelerate the return of emergent plants but had less effect on submergent species or animal communities. Fresh OSPW was toxic to most aquatic life, though toxicity declined with age. Food webs in older, peat-amended wetlands became more similar to natural ones, but recovery remained slower and less complete than in temperate regions. Residual salinity may be the most important regulator of community composition and possibly carbon production. Landscape designs for wetlands should mimic naturally forming wetlands and generate a positive net water balance.