Physical, chemical, biological, and optical oceanographic conditions in the Labrador Sea in 2024

This report summarizes the 2024 findings from the Atlantic Zone Off-Shelf Monitoring Program’s (AZOMP) annual sampling of the AR7W line, covering the Labrador shelf and slope (AR7W-W), central Labrador Sea (AR7W-C), and Greenland shelf and slope (AR7W-E). In 2024, physical conditions were marked by a slightly negative winter NAO index, warmer air temperatures, and below-normal sea ice extent. The water column was generally warmer and fresher than average. Increasing concentrations of SF₆ and Total Inorganic Carbon (TIC) continued, with a TIC spike in 2024 causing a significant drop in pH. A trend in biogeochemical properties persists, with surface and deep nutrient levels remaining below normal since 2019. Integrated chlorophyll-a was slightly below normal, though satellite data showed high surface concentrations and varied bloom timing. Phytoplankton composition differed regionally. The occupation of AR7W began approximately 50 days after the start of the phytoplankton bloom, allowing mesozooplankton abundances time to grow before sampling, resulting in record highs for key species including Calanus finmarchicus, Pseudocalanus spp., Oithona spp., and Euphausiidae. Conversely, Amphipoda abundances have been below normal since 2019, highlighting significant ongoing ecosystem changes in the Labrador Sea.