Thecamoebians (Testate Amoebae) as Proxies of Ecosystem Health in Oil Sands Lakes and Wetlands

The current development of the oil sands in northern Alberta, using surface mining techniques, results in large post-development areas requiring reclamation. Much of the development area was dominated by boreal forest wetlands. Constructed wetlands and lakes are intended to be integral components of the oil sands reclamation plans. There is a need for an easy to apply indicator of how the impacted areas are evolving/ moving toward healthy ecosystems consistent with pre-disturbed aquatic systems. The microbial and protistan components are early colonisers of disturbed sites, as they are able to tolerate and even exploit some of the by-products of mining and processing of the oil sands. Thecamoebians (testate amoebae) are protists found in all moist fresh to brackish environments, where they play a critical role in food webs as the intermediate between bacterial and benthic invertebrate communities. Thecamoebian assemblages from sites located at the Suncor Energy Inc. constructed wetland test facility were found to be sensitive proxies of environmental quality, and promise to be excellent bio-indicators of remediation efforts. The ratio of difflugiid to centropyxid/ arcellid thecamoebians appears to be a simple and effective metric for determining the degree of impact from oil sands process-affected materials (OSPM). Samples dominated by difflugiid thecamoebians (less tolerant to adverse conditions) were associated with sediments less impacted by OSPM, whereas centropyxid and arcellid thecamoebians characterize sites containing young/ fresh OSPM. The environmental sensitivity and rapid generation time of these protozoan microfossils allow for evaluation of the success of various reclamation options (e.g. nutrient loading) in the early stages, allowing for better-informed to be made to mitigate the impact of development of this resource.