The Atlantic Zone Off-Shelf Monitoring Program samples the AR7W line annually. This report summarises trends from 2019-2023 for three regions: AR7W-W (Labrador shelf and slope), AR7W-C (central Labrador Sea), and AR7W-E (Greenland shelf and slope). Samples revealed a continued increase in dissolved inorganic carbon and a decrease in pH from 2019 to 2023. Mean concentration of CFC-12 decreased in 2020, and SF6 continued its steady increase. Mean temperature from 0-100 m in the Labrador Sea was above normal in 2019, below normal on the next mission (2022), and near or above normal in 2023. Surface (0-100 m) nutrients were mainly below normal from 2019-2023, which could be attributed to mission timing. However, below-average deep nutrients (>100 m, less impacted by sampling timing) suggests a profound change in the biogeochemistry of the Labrador Sea. Integrated (0-100 m) chlorophyll-a was below normal in 2019 and in AR7W-E in 2022-2023, but above normal elsewhere, with a record high value in AR7W-C in 2022 caused by an unusually large bloom of Phaeocystis spp.. Satellite data revealed high variability in the timing of the spring and fall blooms and surface average chlorophyll-a concentration. Mesozooplankton abundances showed high interannual variability since 2019.
Ringuette M., Clay S., Devred E., Azetsu-Scott K., Gabriel C. E. & Childs D., 2025. Chemical and biological oceanographic conditions in the Labrador Sea from 2019 to 2023. Canadian Technical Report of Fisheries and Aquatic Sciences 3696. Report.
