Understanding ecologic response to climate cycles will aid in defining current and future ecological changes associated with climate change and allow for a differentiation between climate-driven versus anthropogenic driven environmental stresses.
The paleoecological record from a northern Canadian lake located 40 km east of the Athabasca Oil Sands operation records a benthic stress-induced ecological response to climate cycles such as the El Niño Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO). Arcellacea (testate lobose amoebae) preserved in a freeze core obtained from “ALE”, an upland lake in Northeastern Alberta, Canada, were used to reconstruct climate and associated benthic response since 1875 A.D. ALE is situated in a boreal wetland environment where inorganic sediment delivery is overwhelmingly dominated by surface overland flow transport during spring melt. Arcellacea are benthic protists that are excellent indicators of aquatic ecology. Relationships between arcellacean family groupings which represent either healthy or stressed environmental conditions were compared to instrumental climate indices. Modeling using wavelet analysis identified strong ENSO cycles in all arcellacean proxies and weaker PDO cycles in only the healthy ecosystem indicator. The ENSO phenomenon in the tropical Pacific Ocean drives the largest interannual variation in climate across western Canada, and in the study region has been associated with fluctuations in winter precipitation and temperature. The healthy ecosystem indicators decreased in response to positive El Niño and PDO conditions, which are characteristic of decreased precipitation and therefore nutrient input to boreal lakes.
The relationship between arcellaceans and climate anomalies shows that climate driven variations in nutrient input influence boreal aquatic ecology. The link between aquatic ecology and climate has significant implications on oil sands risk assessment and the determination of reclamation endpoints.