ARCUS | Arctic Research Consortium of the United States

7th Annual ARCUS Award for Arctic Research Excellence


Submitted by   Neal Michelutti
Authors   Neal Michelutti, M. S. V. Douglas, and J. P. Smol
Category   Interdisciplinary Research
Title   Limnological and Paleolimnological Analyses of Two High Arctic Lakes on Cornwallis Island, Candian High Arctic: Examining the Impacts of Recent Climate Changes and Human-Induced Eutrophication
Affiliation   Biology, Queen's University, Kingston, ON, Canada

Abstract

From 1968-72, Char and Meretta Lakes (Cornwallis Island, Canadian Arctic) were the sites of several limnological studies conducted during the International Biological Programme (IBP). However, since then, little research has been done on either lake. Since 1992, we've sampled both lakes for water chemistry, periphyton, and have collected sediment cores for paleolimnological analyses. In Char Lake, there were no major differences between our water quality data and those collected during the IBP. Our paleolimnological study revealed a shift in the fossil diatom assemblages beginning around 1987. The timing of this species shift does not correspond to the deposition of atmospherically-transported persistent organic pollutants into the lake (beginning in the early-1950s) or to minor disturbances within its catchment (early-1970s). Instead, these subtle diatom changes are consistent with recent climatic changes during 1988-97 (as documented by local meteorological measurements), and are likely related to reduced summer ice-cover and a longer growing season.

Meretta Lake received raw sewage for almost 50 years from the Canadian Department of Transport Base. In this study, we demonstrated for the first time that a high arctic lake can recover from chronic nutrient loading once inputs into the lake cease. We developed an annual diatom-based monitoring approach, and were able to show that the diatom assemblages were tracking changes in the lake’s nutrient levels. We also showed that the recent sediments contained fossil diatom assemblages representative of pre-impact conditions, indicating that the paleolimnological record is also tracking the decreased nutrient inputs, and that no significant lags exist in these largely ice-covered lakes.

Our data show that recent climatic changes have resulted in unprecedented ecological changes in a large high arctic lake, and also provide rare information on eutrophication processes in arctic regions.