Shifting Foundations of the Antarctic Food Web with Sea Ice Loss

This study examines how sea-ice loss is reshaping the Antarctic food web by driving shifts in phytoplankton communities. Using random-forest models trained on in-situ pigment data, integrated with environmental datasets and satellite observations, we estimated the chlorophyll-a of three key phytoplankton groups (diatoms, haptophytes, and cryptophytes). The results reveal both overall changes in chlorophyll-a and major shifts in key groups with implications for ecosystems and carbon cycling in the Southern Ocean. Between 1997 and 2023, diatoms declined while haptophytes and cryptophytes increased, indicating a fundamental restructuring of the phytoplankton base of the food web around Antarctica. These concurrent changes in sea-ice coverage and community composition underscore the vulnerability of Antarctic marine ecosystems to climate change and highlight the ecological importance of long-term monitoring phytoplankton group dynamics.

Reference: Hayward, A., Wright, S.W., Carroll, D., et al. (2025). Antarctic phytoplankton communities restructure under shifting sea-ice regimes. Nat. Clim. Change, 15(8), 889–896. https://doi.org/10.1038/s41558-025-02379-x