Nitrogen fixation across the aquascape: current perspectives, future priorities

Di-nitrogen (N₂) fixation rates, and the diversity of the organisms that fix N₂, remain largely unconstrained in the aquatic landscapes or aquascapes (e.g., lakes, wetlands, streams, rivers, estuaries) between land and sea. As a result, we lack a mechanistic understanding of the controls and contributions of N₂ fixation across disparate aquatic environments, and cannot accurately incorporate this process into local and global nitrogen (N) budgets. This special issue brings together papers highlighting current advances in understanding of N₂ fixation within and across all aquatic habitats, integrating novel methodology for studying N₂ fixation, quantification of N₂ fixation fluxes in understudied habitats, the role of N₂ fixation in biotic assemblages, and the rate and fate of fixed N in heterogeneous landscapes. Together, these papers address important gaps in understanding and highlight the frontiers of research on N₂ fixation in aquatic habitats.