Ocean Seminar: "Facing the unknown: modern planktonic foraminifera migration is not enough", by Sonia Chaabane

The Ocean's Challenge groups are organizing a new seminar by Sonia Chaabane, from the IRD CEREGE, Aix-en-Provence, France.

Seminar: "Facing the unknown: modern planktonic foraminifera migration is not enough" 

Speaker: Sonia Chaabane, IRD CEREGE, Aix-en-Provence, France

• Date: Thursday, 12th of November 2026
• Time: from 13 to 14h
• Venue: Room Z/033, ICTA-UAB and online https://zoom.us/j/92074418017?pwd=NZKbGoHsC3FiLEPn3I1SbZm5ALD6ab.1

Rising atmospheric CO₂ concentrations are driving ocean warming and acidification, reshaping marine habitats and threatening calcifying organisms such as planktonic foraminifera. These microorganisms play an important role in marine biogeochemical cycles, while their fossil record provides valuable archives of past environmental and climatic changes. However, their responses to ongoing climate change, particularly their capacity to adapt through geographical and vertical migration, remain poorly understood at the global scale.

To address this knowledge gap, the FORCIS (Foraminifera in a Changing Ocean) project has compiled the most comprehensive database to date of living planktonic foraminifera distributions, encompassing over 180,000 samples collected since 1910 across different ocean basins, depths, and sampling techniques. This extensive dataset provides a unique opportunity to investigate long-term changes in species abundance, diversity, and ecological niches in response to changing ocean conditions.

Our century-scale analyses reveal substantial poleward shifts in planktonic foraminifera distributions, accompanied by increasing diversity at mid- and high latitudes. Several species have also shifted their vertical habitats towards deeper, cooler waters, potentially as a response to warming surface conditions. Despite these movements, global planktonic foraminifera abundance has declined by 24.2 ± 0.1% over the last eight decades.

Looking ahead, projections for 2050 and 2100 suggest that tropical species will increasingly experience environmental conditions beyond their currently observed ecological niches, particularly in terms of temperature and carbonate chemistry. Ecological niche models further predict habitat contractions, continued poleward redistribution, and potential biodiversity losses in tropical oceans.

Together, these findings suggest that although geographical and vertical migration represent important responses to climate change, they may not be sufficient to compensate for the accelerating pace of ocean warming and acidification. These changes also have important implications for marine biodiversity, ocean carbon cycling, and the reliability of planktonic foraminifera as paleoceanographic proxies.