Intracellular nitrate storage by diatoms can be an important nitrogen pool in freshwater and marine ecosystems

Abstract Identifying and quantifying nitrogen pools is essential for understanding the cycle in aquatic ecosystems. The ubiquitous diatoms represent an overlooked nitrate pool as they can accumulate intracellularly utilize it assimilation, dissipation of excess photosynthetic energy, Dissimilatory Nitrate Reduction to Ammonium (DNRA). Here, we document global co-occurrence intracellular phototrophic microbial communities freshwater ( n = 69), coastal 44), open marine 4) habitats. Diatom abundance total contents water columns, sediments, mats, epilithic biofilms were highly significantly correlated. In contrast, diatom community composition had only a marginal influence on contents. concentrations inside cells exceeded ambient ?100–4000-fold. collective accounted <1% pelagic habitats 65–95% benthic Accordingly, nitrate-storing are emerging significant contributors cycling, particular through activity under anoxic conditions.