Spatial and temporal variation in nitrogen fixation and its importance to phytoplankton in phosphorusârich lakes
Limnological theory posits that phosphorus (P) limits primary production in freshwater lakes, in part because fixation of atmospheric nitrogen (N2) can compensate for limitations in nitrogen (N) supply to phytoplankton. However, quantitative estimates of the degree to which N2 fixation satisfies planktonic N demand are rare.