Assessing Thule Inuit impacts on High Arctic lakes and ponds : a paleolimnological approach

Abstract

Until recently it has been widely believed that significant anthropogenic influences on the environment began in Canada following the onset of European colonization. However, our paleolimnological data indicate that centuries prior to European settlement, ponds on Ellesmere and Bathurst Island were impacted by Thule Inuit whalers, whose activities altered nutrient levels in nearby ponds. Two Thule Inuit whaling sites were selected based on input from several archaeologists, to ensure good coverage of the Thule geographic range and proximity to freshwater ponds. Multiple independent paleolimnological proxies have been used to analyze a pond from Ellesmere Island, showing taxonomic shifts in diatoms assemblages coinciding with 1.5 - 2‰ shifts in d15N, during the period of Thule occupation (ca. 1000 – 1670 AD). Increases in the relative abundance of Amphora ovalis, indicate nutrient concentrations above average for the High Arctic. Elevated levels of nitrogen and phosphorus were observed in the pond indicating the continuing influence of nutrient inputs centuries after the abandonment of the camp. Meanwhile, on Bathurst Island, the orientation of the Deblicquy site, such that the large majority of the Thule nutrient inputs are focused towards one of our two study ponds, provided us with the opportunity to compare two ponds that are essentially identical with the exception of the degree of Thule influence. In our “impacted” site, a marked increase in Stephanodiscus minutulus, coincides with a 2‰ shift in d15N. While our a priori determined control site shows no major changes in geochemistry or algal composition. Previous research on Bathurst Island used water chemistry and surface sediment diatoms to construct a diatom-inferred total nitrogen model for Bathurst Island. However, this study was limited by excluding unbuffered, low pH sites which characterize the western half of Bathurst Island. By expanding the previous Bathurst Island dataset to include western sites, we have been able to construct a diatom-inferred pH model which will prove invaluable in future climate research in this region. Together, these three studies serve to highlight the sensitivity of freshwater ecosystems to relatively minor anthropogenic disturbances and represent some of the earliest known anthropogenic impacts on North American aquatic ecosystems.