Long-term satellite data reveals complex phytoplankton dynamics in the Ross Sea, Antarctica

Abstract The Ross Sea (Southern Ocean) hosts diverse marine ecosystems like polynyas and marginal ice zones. In recent decades, multiple environmental changes (e.g., water temperature increase, sea ice retreat) have affected local biological communities, including phytoplankton. These microscopic organisms support Antarctic food webs and contribute to global carbon sequestration. Here, we analyse 24-years (1998–2021) of satellite and model data to understand spatial-temporal phytoplankton patterns and their environmental drivers. Using a clustering analysis, we identified three subregions with distinct phytoplankton patterns. The oceanic subregion, phytoplankton showed lower biomass and longer-lasting blooms driven mainly by winds. The coastal subregion, where polynyas occur, had high biomass and short blooms primarily influenced by sea ice and wind. The intermediate subregion exhibited variable blooms characteristics linked to sea ice dynamics. Our findings highlight the role of physical drivers in shaping phytoplankton variability and underscore the importance of long-term monitoring for understanding ecosystem responses to environmental change.