Ambiguous controls on simulated diazotrophs in the world oceans
Nitrogen fixers, are microorganisms that fix nitrogen from the air, making it available for ecosystems. It is known that they grow rather slowly so that they are easily taken advantage of by fast-growing algae – unless there is a lack of bioavailable nitrogen. This is when their unique property of “fixing” the nitrogen from the air comes into play. Surprisingly, nitrogen fixers in the ocean often fix more nitrogen than they need themselves – a property that still puzzles researchers, because it ultimately reduces their typical habitats, which are characterized by a lack of bioavailable nitrogen. The novel study, recently published in the Journal Nature Scientific Reports examines other more complex regulatory mechanisms that can give diazotrophs advantages. A series of model simulations illustrates the potential importance of predators and different nutrient limitations. This illustrates considerable uncertainties (up to sign changes) in projections of nitrogen fixation.