High‐Resolution Primary and Net Community Productivity Estimates in the Southeast Bering Sea From Moored Observations

Abstract The Bering Sea is a highly productive subarctic ecosystem with some of the most valuable commercial fisheries in the United States. This seasonally ice‐covered sea has been rapidly changing due to ocean warming with impacts to the ecosystem structure and fisheries. The long‐term effects of these shifts on primary producers, however, are still unknown. Continuous monitoring of primary productivity in the Bering Sea is critical, yet observations that capture the ephemeral nature of plankton are challenging to sustain. To address this gap, high temporal resolution primary productivity rates were quantified at a mooring site (M2) in the southeastern Bering Sea in 2021. From a suite of sensors at M2 (fluorescence, dissolved oxygen, temperature, and total dissolved gas pressure), we calculated gross primary productivity (GPP), net primary productivity (NPP), and net community productivity (NCP), the latter based on net biological oxygen saturation using dissolved oxygen/nitrogen (O 2 /N 2 ) ratios. These estimates elucidate weekly patterns from the spring bloom through fall, when the water column becomes well‐mixed. In 2021, we observed average productivity during the spring bloom, yet wind patterns and mixing dynamics during the spring contributed to low productivity during summer and fall. The 2021 productivity metrics (GPP, NPP, and NCP) were compared across the growing season and contrasted with seasonal productivity estimates at M2 in previous years with consideration given to variability of ice conditions (warm/cold years) and wind stress.