Linking deep convection and phytoplankton blooms in the northern Labrador Sea in a changing climate

• Published in: PLOS ONE
• Main Authors: Balaguru, Karthik, Doney, Scott C., Bianucci, Laura, Rasch, Philip J., Leung, L. Ruby, Yoon, Jin-Ho, Lima, Ivan D., Dias, João Miguel
• Language: unknown
• Published: 2023
• Subjects: 54 ENVIRONMENTAL SCIENCES; Arctic; Labrador Sea; North Atlantic; Phytoplankton; Sea ice
• Online Access: http://www.osti.gov/servlets/purl/1439649; https://www.osti.gov/biblio/1439649; https://doi.org/10.1371/journal.pone.0191509

Wintertime convective mixing plays a pivotal role in the sub-polar North Atlantic spring phytoplankton blooms by favoring phytoplankton survival in the competition between light-dependent production and losses due to grazing and gravitational settling. We use satellite and ocean reanalyses to show that the area-averaged maximum winter mixed layer depth is positively correlated with April chlorophyll concentration in the northern Labrador Sea. A simple theoretical framework is developed to understand the relative roles of winter/spring convection and gravitational sedimentation in spring blooms in this region. Combining climate model simulations that project a weakening of wintertime Labrador Sea convection from Arctic sea ice melt with our framework suggests a potentially significant reduction in the initial fall phytoplankton population that survive the winter to seed the region's spring bloom by the end of the 21st century.