Spatial Patterns of Arctic Organic Matter as a function of Phytoplankton Composition

durch Sophia Hirschmann

Mittwoch 17.09.2025, 13:15 → 14:30 Europe/Berlin

8A-002 - Hörsaal Ostufer / Lecture Hall East (GEOMAR - Standort Ostufer / GEOMAR - East Shore)

Climate change is altering Arctic phytoplankton dynamics with largely unknown consequences on the organic matter pool and biogeochemical fluxes. Here, we investigated the organic matter pool, including carbohydrates and transparent exopolymer particles (TEP), together with phytoplankton community composition in the Fram Strait (LTER Hausgarten), the Kara Sea (Arctic Century), and its estuary, regions currently experiencing a decrease in sea ice extent and thickness, enhanced advection of warmer waters, and an increase in river discharge. Our results showed significant differences between the three geographical regions, both in phytoplankton community composition and carbohydrate composition. In the Fram Strait, the haptophyte Phaeocystis pouchetii significantly correlated with elevated proportions of arabinose and rhamnose and up to five-fold higher concentrations of TEP, suggesting a link between enhanced TEP formation and Phaeocystis exudates. In contrast, the Kara Sea estuary was characterised by high proportions of acidic sugars and cryptophytes (Teleaulax), while the remaining Kara Sea showed high relative abundances of diatoms (Eucampia and Thalassiosira) and pronounced relationships of dinoflagellates (e.g., Karlodinium) with amino sugars. These results suggest that climate-driven changes in Arctic phytoplankton communities are likely to alter the organic matter pool and, in turn, the formation of TEP and associated export processes.