Banse Early Career Scientist Seminar

Wednesday, January 24, 03:30 PM to 04:30 PM PST

Ocean Sciences Building (OSB), Room 425 with tea and cookies to follow

Attend Virtually: https://washington.zoom.us/j/97950908901

Hannah Joy-Warren, UW APL

Title: Understanding the Connections Between Phytoplankton Community Composition and Carbon Uptake in the Southern Ocean

Abstract: The Southern Ocean has historically been considered a strong carbon dioxide (CO2) sink—responsible for ~40% (~1 PgC) of anthropogenic CO2 that enters the ocean—but its efficacy as a CO2 sink may be more variable than previously thought. The Southern Ocean is also responsible for ~30% (~3.3 PgC) of annual global organic carbon export, thereby exerting substantial influence on global climate. Prior research has identified connections between the strength of the Southern Ocean CO2 sink and natural oscillations in oceanic circulation, but less work has been done to evaluate the contribution of biological factors.  Phytoplankton are a key driver in global carbon cycling through photosynthesis and potential export of organic carbon to the deep ocean, but different taxa contribute differently to carbon drawdown and export, with potential implications for the overall impact of phytoplankton on air-sea CO2 flux.  In this work, a newly-developed database of phytoplankton observations is used together with a data-assimilating coupled biogeochemical-physical model of the Southern Ocean and a species distribution model to estimate phytoplankton taxa distributions at the location of Biogeochemical-Argo float profiles.  These taxa distributions are then evaluated in conjunction with air-sea CO2 fluxes estimated from the float observations, in order to better understand the connections between variability in the Southern Ocean CO2 sink and phytoplankton community composition.