NIPROFEED · Unravelling the Nitrogen Fixation-Primary Production Feedback Loop: Implications for Carbon Cycling and Oceanic Health

The project ‘NIPROFEED’ delves into the vital interplay between primary producers, nitrogen fixation, and particle dynamics in aquatic ecosystems. Primary producers play a crucial role in capturing roughly one third of excess carbon dioxide and converting it into organic particles, central to the ocean's biological pump. This process, however, contributes to oxygen depletion as sinking particles lead to organic matter respiration and subsequent deoxygenation of bottom waters. Diazotrophs, specialised microbes capable of nitrogen fixation, provide a significant portion of nitrogen input into oceans, supporting primary production. NIPROFEED introduces the hypothesis that diazotrophs supplying nitrogen to primary producers can amplify particle formation, initiating a positive feedback loop that impacts carbon export and oxygen levels. To explore this feedback loop, NIPROFEED will employ cutting-edge techniques, including high-throughput sequencing, single-cell rate measurements and biogeochemical modelling. This will unravel the composition and functional role of free-living and particle-bound diazotrophs, shedding light on their contribution to nitrogen/carbon fixation. By implementing these parameters into an integrated model the intricate relationship between nitrogen fixation and primary productivity will be investigated. Addressing this hypothesis, NIPROFEED aspires not only contribute significantly to scientific advancements in the field of marine science but also aligns with EU sustainability goals by shedding light on climate change impacts on our ocean.