Assessing climate-related disturbations and change on phytoplankton community compositions and hypoxia using color remote sensing

Completion expected September 2025

The Challenge

Ocean color remote sensing has revolutionized our understanding of coastal ecosystems processes by providing continuous mapping important biogeochemical indicators with high spatiotemporal resolutions. Phytoplankton, which contributes about 50% to the global primary production, plays an important role in the global carbon cycle in aquatic environment via the biological pump. Our recent ocean color studies in the estuaries and shelf waters of the northern Gulf of Mexico (nGoM) has revealed the strong phytoplankton community responses, including harmful algal blooms (HABs) following the passage of two hurricanes (Harvey in 2017 and Michael in 2019) and under flood discharge conditions of the Mississippi and Atchafalaya Rivers in 2019 (Liu et al. 2019; D’Sa et al. 2019; Liu et al. 2021).

The Approach

In this NASA-funded project, we propose to assess ecosystem responses (e.g., algal blooms, phytoplankton community structure, hypoxia) to climate-related perturbations and change (e.g., hurricanes, flooding, changing river discharge) in the nGoM shelf influenced by the Mississippi and Atchafalaya Rivers using long-term multi-satellite data including (MODIS, Sentinel 3A/B-OLCI, Landsat 5/8/9 and Sentinel 2-MSI). Bio-optical in-situ measurements along with deep learning technique, and recently developed semi-analytic/inversion algorithms optimized for the estuarine-ocean continuum will be used to generate long-term biogeochemical indicators including Chl-a, phytoplankton functional types (PFTs), phytoplankton size class (PSC) and dissolved organic carbon (DOC) to study climate variability and change effects on a coastal ecosystem influenced by the largest river in North America.