Environmental change observed from two urban Arctic lakes in Iqaluit, Nunavut†

Arctic ecosystems are considered to be especially vulnerable to the effects of environmental change, but the combined influence of a warming Arctic and expanding urban development is less clear. While temperature-driven change has long been the principal focus of studies on Arctic lakes, increasing local human populations, inadequate municipal infrastructure, and expansion of the resource extraction industry may now have a larger influence. Here, we present a chironomid-based paleolimnological assessment of two lakes within the urban boundary of Iqaluit, Nunavut, to determine responses to changes in climate over the Anthropocene. Iqaluit is one of the largest urban centers in the Canadian Arctic with a population that has been increasing for decades and a history of pollution that has affected nearby freshwater systems. We observed warming in both lakes, inferred by a reduction of cold-water stenotherms, such as Heterotrissocladius and Corynocera oliveri-type, concurrent with increases in generalist taxa, including Psectrocladius and those of the tribe Tanytarsini. We note that the two lakes had differences in their assemblages related to the specific habitats associated with each; IQ04 is a large kettle lake with a pronounced profundal zone, whereas IQ01 is oblong with a larger shallow littoral reach. We found that both lakes were responsive to climate, both indicating a warming trend that began ∼1985–1990, regardless of the proximity to human activities, and note that it is important that these ecosystems be monitored given continued environmental stress expected with future warming and further urban development.