Seasonal ice cover and catchment changes at northern thermokarst ponds in Nunavik: Observations from automated time-lapse cameras

Thermokarst ponds and lakes are common features of Arctic and subarctic landscapes, developing in depressions that result from the thawing of ice-rich permafrost. Most of these water bodies are shallow (< 1m depth), and they are widespread in lowland areas of western and northern Alaska, Canada and Siberia. Studies into the dynamics and evolution of these widespread thaw ponds and lakes in the Northern Hemisphere are sparse. However, direct on-the-ground observations (monitoring) are necessary to gain a better understanding of their seasonal dynamics and role in the global carbon cycle.

Weather-resistant time-lapse cameras were installed on trees and other solid metal surfaces (rods) within the catchment of 5 subarctic thermokarst ponds for year-round continuous monitoring/observation and documentation of changes in their physical conditions (e.g., ice cover, water transparency, water level, littoral aquatic vegetation) and their surrounding catchment (e.g., seasonal vegetation change, wildlife activities). This information is of crucial importance to help understand and interpret many lake physical and catchment processes that occur during the winter months, changes that otherwise could not be observed due to the harsh climatic winter conditions and the remoteness of these northern sites.

Materials and methods
Reconyx PC800 Professional cameras were installed on metal support rods or coniferous trees at approximately 5-10 m distance from the edge (peripheral bulge) of thermokarst lakes and ponds, taking 6 photos every day at 1 hour intervals between 10:00 AM and 15:00 PM Eastern Standard Time (EST). The cameras were protected in a metal housing to minimize environmental hazards and damage. The cameras were placed at 2-3 meters height above ground.