Phys.org  October 17, 2022 Diazotrophs are widespread microorganisms that alleviate nitrogen limitation in 60% of our oceans, thereby regulating marine productivity. Yet, the group-specific contribution of diazotrophs to organic matter export has not been quantified. An international team of researchers (France, Israel, Spain) examined the fate of five groups of globally distributed diazotrophs by using an original combination of mesopelagic particle sampling devices across the subtropical South Pacific Ocean. They demonstrated that cyanobacterial and non-cyanobacterial diazotrophs are exported down to 1000 m depth. Phycoerythrin-containing UCYN-B and UCYN-C-like cells were recurrently found embedded in large organic aggregates or organized into clusters of […]