Eddy-Driven Stratification Initiates North Atlantic Spring Phytoplankton Blooms

• Published in: Science (American Association for the Advancement of Science) Vol. 337; no. 6090; pp. 54 - 58
• Main Authors: Mahadevan, Amala, D'Asaro, Eric, Lee, Craig, Perry, Mary Jane
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 06.07.2012; The American Association for the Advancement of Science
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Atlantic Ocean; Biological and medical sciences; Blooms; Chlorophylls; Climate; Climate models; Climatology. Bioclimatology. Climate change; Cooling; Density; Earth, ocean, space; Ecosystem models; Eddies; Eutrophication; Exact sciences and technology; External geophysics; Fundamental and applied biological sciences. Psychology; Heat flux; Light water; Marine ecology; Meteorology; Models, Biological; Models, Theoretical; Ocean models; Oceans; Photosynthesis; Phytoplankton; Phytoplankton - growth & development; Plankton; Robotics; Sea water ecosystems; Seasons; Seawater; Spring; Spring (season); Stratification; Sunlight; Surface cooling; Synecology; Temperature; Water circulation; Water Movements; Atlantic Ocean; North Atlantic; Dynamical climatology; Marine environment; Warming; Climate change; Sea surface; Sea current; Spring(season); Bloom; Phytoplankton; Subpolar zone; Stratification
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1218740

Springtime phytoplankton blooms photosynthetically fix carbon and export it from the surface ocean at globally important rates. These blooms are triggered by increased light exposure of the phytoplankton due to both seasonal light increase and the development of a near-surface vertical density gradient (stratification) that inhibits vertical mixing of the phytoplankton. Classically and in current climate models, that stratification is ascribed to a springtime warming of the sea surface. Here, using observations from the subpolar North Atlantic and a three-dimensional biophysical model, we show that the initial stratification and resulting bloom are instead caused by eddy-driven slumping of the basin-scale north-south density gradient, resulting in a patchy bloom beginning 20 to 30 days earlier than would occur by warming.