CLIMATIC DRIVERS OF LIMNOLOGICAL CHANGE IN IQALLUKVIK LAKE, TUKTOYAKTUK, NORTHWEST TERRITORIES, CANADA

The Tuktoyaktuk coastlands contain thousands of lakes along an area of the Beaufort Sea in the rapidly changing western Arctic. These lakes may be susceptible to a range of impacts associated with climate warming, including potential increased marine influence changes associated with reduced lake ice cover and thawing permafrost. We examined a 210Pb-dated sediment core from Iqallukvik Lake to reconstruct ecosystem change over the last several hundred years using sediment particle size analysis and diatom subfossils. Changes in sediment texture over the past ~200 years were broadly aligned with inferred changes in regional precipitation, known to be an important driver of regional lake level in the Tuktoyaktuk coastlands. Diatoms were functionally absent at the bottom of the sediment core, but increased after ~1850, likely in response to early warming, with further floristic changes due to accelerated warming over the last century. Diatoms throughout the core are predominantly freshwater species tolerant of broad salinity concentrations, indicating Iqallukvik Lake is likely subject to minimal direct marine influence and has not been impacted by notable inundation over the recent past. Overall, this research suggests that climate impacts to Iqallukvik Lake mainly the length of the ice-free season.