Evidence of eutrophication in Arctic lakes

Lakes and ponds are dominant components of Arctic landscapes and provide food and water for northern communities. In the Greiner Lake watershed, in Cambridge Bay (Nunavut, Canada), water bodies are small (84% <5 ha) and shallow (99% <4 m deep). Such characteristics make them vulnerable to eutrophication as temperatures rise and nutrient concentrations from the greening landscape increase. Here, we investigated and compared 35 lakes and ponds in the Greiner watershed in August 2018 and 2019 to determine their current trophic states based on their chemical composition and phytoplankton commun-ities. The ponds had higher trophic status than the lakes, but overall, most sites were oligo-trophic. Lake ERA5, located upstream of any direct human influence was classified as eutrophic due to high total phosphorus (32.3 mu g center dot L-1) and a high proportion of Cyanobacteria (42.9% of total phytoplankton biovolume). Satellite imagery suggests the lake may have been eutrophic for the last 30 years. We hypothesize that the coupled effects of catchment characteristics and elevated local snow accumulation patterns promote higher nutrient leaching rates from the soils. We recommend further analysis and monitoring as eutrophication could become more widespread with ongoing climate change and the asso-ciated increases in temperature, precipitation, and catchment-lake coupling.

Automated summary

The study found that most lakes and ponds in the Greiner Lake watershed are oligotrophic, but some lakes influenced by direct human activities are more susceptible to eutrophication. This could be due to the combined effects of catchment characteristics and elevated local snow accumulation patterns.