Abstract
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 changes 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 that 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 Iqallukvik Lake mainly on the length of the ice-free season.
Highlights
High-latitude regions are being rapidly altered due to warming air temperatures and a wide range of associated environmental changes
The 210Pb activity measured in the sediment core from Iqallukvik Lake exhibited an approximately exponential decline, reaching background after a core depth of 20 cm (Fig. 2A)
An insufficient number of diatom valves were present in the deepest section of the sediment core, which prevented us from providing a reconstruction of the diatom assemblage from ∼25 cm to the bottom of the core at 40.5 cm
Summary
High-latitude regions are being rapidly altered due to warming air temperatures and a wide range of associated environmental changes. Arctic air temperatures continue to increase at more than double the global rate (Walsh 2014). Sea level rise, predicted at a global scale, poses an additional threat to Arctic coastal regions, those that are low-lying, such as delta environments. Rising sea levels, combined with decreased sea ice extent and increases in temperature, may trigger more severe storms and can generate large shorelineeroding waves and storm surges (Kobayashi et al 1999). In the western Arctic, the coastlines of the mainland beaches along the Beaufort Sea are retreating at a rapid rate, with some areas exceeding 1 m yr−1 (Harper 1990; Hequette and Barnes 1991; Jones et al 2008; ) due to the combined influ-
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