Tracking Long-Term Environmental Changes in Arctic Lakes and Ponds: A Paleolimnological Perspective

Abstract

Rock Basin Lake, Baird Inlet (east-central Ellesmere Island, Nunavut, Canadian High Arctic) was the site of the first detailed paleolimnological study from the circumpolar region, which used diatom and chrysophyte microfossils to track past climatic change. Photo: John P. Smol, August 1987. H IGH-LATITUDE REGIONS have repeatedly been identified as important reference areas for environmental change research, as they are especially sensitive to even small climatic changes and are often the first to show signs of environmental shifts. Moreover, climatic changes occurring at high latitudes have profound effects on other regions. Unfortunately, long-term monitoring data are generally lacking for most regions, and this is especially true for the Arctic. Without these data, it is difficult to determine whether environmental conditions are changing, and if so, to specify the magnitude and direction of change. Fortunately, a variety of natural archives of environmental change (e.g., ice cores) can be used to reconstruct these missing data sets. One rapidly emerging area of research in the Arctic is paleolimnology, which is the science of reconstructing past lake and pond histories from the proxy data contained in sediment profiles (Smol, 2002). As lakes represent a common feature of most Arctic regions, paleolimnological techniques have now been applied to a wide variety of research questions (Pienitz et al., 2004). Dated sediment cores typically archive a very rich history of past limnological conditions, based on indicators such as fossil algae (especially diatoms and chrysophytes) and invertebrates (such as Cladocera and aquatic insect remains), as well as a suite of physical and chemical indicators, such as metals and contaminants (Smol, 2002). My Arctic limnology and paleolimnology research program began in 1983, when Dr. Weston Blake Jr., now an emeritus scientist at the Geological Survey of Canada, invited me to join his field crew at Cape Herschel on eastern Ellesmere Island. I published an early paper (part of my PhD dissertation) arguing that fluctuating lake-ice conditions (which are closely related to climatic variables) exerted a strong control on lake biota, and hence on the bioindicators preserved in lake sediments. The 1983 field season was the start of a lifelong interest in the limnology and paleoecology of Arctic lakes. In September 1984, I was hired as an assistant professor at Queen’s University, where Marianne Douglas, now a professor in the Department of Geology at the University of Toronto and holder of a Tier 1 Canada Research Chair in Global Change, was among my first cohort of students. We have been collaborating on polar research ever since. For over 20 years, we have been using both limnological and paleolimnological techniques to track a variety of environmental trends throughout the Arctic. I co-direct the