seasonal environmental and chemical impact on thecamoebian community composition in an Oil Sands reclamation wetland in Northern Alberta
Thecamoebian (testate amoeba) communities appear to respond to a variety of chemical parameters in aquatic ecosystems impacted by oil sands operations. A seasonal study, conducted over four seasons from May 2008 to March 2009 (spring, summer, fall and winter) in a constructed aquatic environment at the Mildred Lake site of Syncrude Canada Ltd. in northeastern Alberta, identified species and strain-level variation among living (i.e., Rose Bengal-stained) thecamoebians. The changes in this epibenthic community appeared to reflect seasonal and micro-environmental changes, as little change in the porewater chemistry, composition of sediments or bottom waters was observed over the study interval. The total (living + dead) thecamoebian test assemblage remained relatively constant over the course of the study, suggesting that the fossil assemblage reflects time-averaged conditions. Some variability was, however, observed among the species composing the difflugiid population. In addition, the speed at which they respond to environmental changes emphasizes their potential usefulness as environmental indicators. This has important implications for the use of thecamoebians as paleoenvironmental indicators. The difference between living and total assemblages reflects taphonomic skewing presumably resulting from variations in preservation potential and/or selective predation of species and strains.
Keywords: thecamoebians, oil sands, reclamation, testate amoebae, seasonality, living vs. total assemblages
PE Article Number: 13.2.13A
Copyright: Palaeontological Association July 2010
Submission: 18 January 2009. Acceptance: 19 May 2010