Overwinter oxygen and silicate dynamics in a high Arctic lake (Immerk Lake, Devon Island, Canada)

Abstract

ABSTRACT Arctic lakes are ice covered for 8–12 months of the year, but the duration and thickness of ice cover is decreasing with increased warming. There is a paucity of baseline data documenting the geochemical dynamics of nutrients and oxygen beneath ice cover of high Arctic lakes, a gap that presents a challenge when attempting to understand the impacts of a rapidly changing Arctic on lake ecosystems. We present an annual cycle of temperature, oxygen, and silicate data from Immerk Lake on Truelove Lowland, Devon Island, Canada. Water column oxygen concentrations decreased while silicate concentrations increased during the ice-covered season. Ice cover melting during spring–summer is associated with rapid net decreases of the silicate standing stock at almost 3 times the rate of its net increase over winter. These data show the importance of the extended winter season for regeneration of silicate, an essential nutrient for diatom populations, which are important members of the phytoplankton community and carbon cycle of Arctic lakes. These data collected 60 years ago serve as a benchmark and document the water column oxygen and silicate dynamics in an Arctic lake during ice formation, winter darkness, and ice-cover melting periods.