POSTER SESSION 3
15:30–17:30, Wednesday, September 16
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
ABSTRACT 1266 | POSTER 147
PHYTOPLANKTON FUNCTIONAL DIVERSITY TRENDS IN THE MEDITERRANEAN SEA IN THE LAST 25 YEARS
This study analyzes 25 years (2000–2025) of satellite remote sensing data to assess trends in phytoplankton functional diversity across the Mediterranean Sea. The regional algorithm adopted in Copernicus Marine Service (CMEMS) for the retrieval of Phytoplankton Functional Types (PFTs) was applied to CMEMS gap-free L4 chlorophyll fields. Relative and absolute abundances of six PFTs — Cryptophytes, Diatoms, Dinophytes, Green Algae, Haptophytes, and Prokaryotes — were estimated across nine trophic regions. Results reveal a basin-wide decline in surface chlorophyll concentration alongside a structural shift in phytoplankton assemblages from larger to smaller size classes. In absolute terms, all PFTs show negative trends, while in relative terms Prokaryotes are the only group consistently increasing across all regions, contrasting with Diatoms and Haptophytes, which exhibit the strongest declines. Shannon Index analysis confirms a moderate but widespread decrease in phytoplankton functional diversity, most pronounced in the Western Mediterranean. These compositional changes carry implications for key biogeochemical cycles: the decline of Diatoms may weaken carbon sequestration and the silica cycle, the rise of Prokaryotes could modestly stimulate nitrogen fixation, and the reduction of Dinophytes and Haptophytes may alter sulfur cycling through decreased DMS production. This study underscores the value of satellite-based observations for tracking ecosystem-scale changes and highlights the need for continued assessment of phytoplankton functional diversity as an indicator of Mediterranean Sea health under ongoing climate change.
Gonzalo Martinez-Fornos*, ICM – CSIC, [email protected], https://orcid.org/0009-0000-8860-8667
Annalisa Di Cicco, National Research Council – Institute of Marine Sciences (CNR-ISMAR), [email protected]
Marco Talone, Institut de Ciències del Mar (ICM-CSIC), [email protected]
Elisa Berdalet, Institut de Ciències del Mar (ICM-CSIC), [email protected]
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
