Fine scale sampling unveils diazotroph patchiness in the South Pacific Ocean

Abstract

Diazotrophs are important contributors to reactive nitrogen availability in the ocean. Oceanographic cruise data accumulated along decades has revealed a heterogeneous distribution of diazotroph species at regional to global scales. However, the role of dynamic fine scale structures in distributing diazotrophs is not well understood. This is due to typical insufficient spatiotemporal resolution sampling and the lack of detailed physical studies in parallel. Here we show the distribution of five groups of diazotrophs in the South Pacific at an unprecedented resolution of 7-16 km. We find a patchy distribution of diazotrophs, with each group being differently affected by parameters describing fine scale structures. The observed variability could not have been revealed with a lower resolution sampling, highlighting the need to consider fine scale physics to resolve the distribution of diazotrophs in the ocean.