Quantifying the Vulnerability of Arctic Water Supply Lakes to Environmental Change Through Paleolimnological Assessment

Abstract

Anthropogenic stressors to freshwater environments have perpetuated water quality and quantity challenges for northern communities across Arctic Canada, making drinking water resources a primary concern for Arctic populations. To understand the ecological trajectory of freshwater supply sources, we conducted a paleolimnological assessment on two supplemental sources of freshwater in Igloolik, Nunavut, Canada. A stratigraphic examination of bioindicators (Insecta: Diptera: Chironomidae) allowed for paleotemperature reconstructions with decadal and centennial resolution over the past 2000 years. Between 200 and 1900 CE, the sub-fossil chironomid community was comprised of cold-water taxa, such as Abiskomyia, Micropsectra radialis-type, and Paracladius. Reconstructed temperatures were consistent with known climate anomalies during this period. A rapid shift in the composition of the chironomid community to warm-water adapted taxa (Chironomus anthracinus-type, Dicrotendipes, and Tanytarsus lugens-type) in the late 20th century was observed in both systems. Our results demonstrate that these lake ecosystems are undergoing marked transformations to warmer, more nutrient-rich environments, and suggest water sustainability pressures on freshwater and human systems will likely continue in tandem with ongoing climate change. To contextualize the influence of recent warming and elucidate the status of water resource vulnerability over the longer term, paleolimnological methods can be usefully applied as components of vulnerability assessments.