More Foxes than Hedgehogs: The Case for Nitrogen Fixation in Coastal Marine Sediments

Nitrogen fixation is an important process connecting the vast atmospheric pool of di-nitrogen gas to the biosphere. Nitrogen fixation is an energy intensive process, and it is historically thought to occur only to meet nitrogen demands. However, over the last two decades, research has demonstrated that sediment nitrogen fixation occurs in a variety of coastal environments, including those where reduced nitrogen is abundant. This can be met with skepticism when nitrogen fixation is viewed solely as a nitrogen limitation relief mechanism. Here, I propose that coastal sediments are actually ideal environments for nitrogen fixation and synthesize ideas on why this is the case. My goal is to help the community embrace a new paradigm for sediment nitrogen fixation and to see it as an important and even expected process. In doing so, I hope to motivate future research on the spatial and temporal rate dynamics of sediment nitrogen fixation as well as on the sediment nitrogen fixation community composition and activity.