Responses of Southern Ocean phytoplankton to anthropogenic changes, feedbacks to the atmosphere and impact on the trophic chain

The SO is subject to major global anthropogenic changes, namely warming and acidification of the surface waters, increase in iron (Fe) inputs due to intensification of dust deposition. These disturbances can interact with each other and spread in the ecosystem through modifications of trophic interactions, with impacts on the carbon transfer and storage in the food web. However, the major limitation in anticipating the biological response to these anthropogenic changes is the lack of experimental studies that integrate cumulative effects of multi-faceted changes on the plankton community in the SO. Anthropogenic changes can have additive, antagonist or synergistic effects that differ among phytoplankton species, such that their mixed effects will be driving the response of the phytoplankton assemblage, with cascading effects on the microbial loop and higher trophic levels, and feedback effects to the atmosphere and climate. But this mixed effect remains largely unexplored and limits our understanding of the potential future direction and intensity of the biological carbon pump in the SO. SOPHYAC’s general objective is to better predict and anticipate the SO biological evolution and impacts in response to anthropogenic multi-stressor changes, placing phytoplankton at the center of the project. It is organized in four sub-objectives: (1) understanding the influence of anthropogenic changes (intensification of atmospheric Fe inputs, warming, acidification) on phytoplankton assemblages and productivities, (2) evaluating the consequences on the microbial loop and immediate higher trophic levels (micro-, meso-zooplankton), (3) assessing the feedbacks on climate (efficiency of the biological carbon pump and emissions of gas-phase components and aerosols to the atmosphere), (4) integrating the changes into biogeochemical, end-to-end and atmospheric models that will help developing multi-decade evolution scenarios in the future. 

Platform: RV Marion Dufresne

Location: Loop from La Réunion Island, Amsterdam Island, Crozet Island, Kerlgelen Island and back

Timing: January – February 2024

Contact: Karine Sellegri (k.sellegri<@>