POSTER SESSION 4
10:30–12:30, Thursday, September 17
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
ABSTRACT 1195 | POSTER 60
LINKING PHYTOPLANKTON DIVERSITY AND DISSOLVED ORGANIC MATTER DYNAMICS IN THE TYRRHENIAN SEA (MEDITERRANEAN SEA)
Marine phytoplankton play a key role in regulating carbon cycling and sequestration, yet the links between Dissolved Organic Matter (DOM) production and phytoplankton diversity remain poorly understood. To explore such links.
During the ITINERIS EYES cruise in July 2025, we collected 0–500 m samples of Chromophoric DOM (CDOM) absorption, Fluorescent DOM (FDOM), and Dissolved Organic Carbon (DOC) concentration in the Tyrrhenian Sea (Mediterranean Sea), a region characterized by pronounced summer stratification and intense mesoscale activity. This dataset was complemented with phytoplankton pigment concentrations (HPLC) and cell abundances of major groups measured using an Imaging Flow Cytobot (IFCB).
Results show a clear vertical structure of DOM optical parameters along the transect, with higher CDOM absorption and molecular weight at the level of the Deep Chlorophyll Maximum (located around 80 m), where diatoms and large cells were more abundant. Lower CDOM concentrations were instead observed at the sea surface, associated with small-sized phytoplankton such as prasinophytes and other small flagellates. However, when crossing a cyclonic structure, DOM distribution and phytoplankton communities showed further variability. CDOM displayed a clear mesoscale pattern, with reduced absorption values in the eddy core and enhanced values at its edges along the transect. These edge regions coincided with higher phytoplankton diversity and a larger contribution of diatoms.
Overall, these results highlight the combined influence of vertical stratification and mesoscale dynamics on phytoplankton community structure and associated DOM properties, suggesting that circulation patterns may act as transient hotspots of biological production and carbon cycling.
Simona Denni*, National Research Council (CNR), Institute of Marine Sciences (ISMAR), Italy, [email protected]
Elisabetta Canuti, European Commission, Joint Research Center (JRC), Italy, [email protected]
Stefano Cozzi, National Research Council (CNR), Institute of Marine Sciences (ISMAR), Italy, [email protected]
Claudia Fanelli, National Research Council (CNR), Institute of Marine Sciences (ISMAR), Italy, [email protected]
Mengyu Li, National Research Council (CNR), Institute of Marine Sciences (ISMAR), Italy, [email protected]
Giovanni La Forgia, National Research Council (CNR), Institute of Marine Sciences (ISMAR), Italy, [email protected]
Vincenzo Vellucci, Sorbonne Université, CNRS, Insitute de la Mer de Villefranche (IMEV – LOV), France, [email protected]
Emanuele Organelli, National Research Council (CNR), Institute of Marine Sciences (ISMAR), Italy, [email protected]
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
