Impact of intensifying nitrogen limitation on ocean net primary production is fingerprinted by nitrogen isotopes Buchanan, P. J. /Aumont, Olivier Bopp, L. Mahaffey, C. Tagliabue, A. The open ocean nitrogen cycle is being altered by increases in anthropogenic atmospheric nitrogen deposition and climate change. How the nitrogen cycle responds will determine long-term trends in net primary production (NPP) in the nitrogen-limited low latitude ocean, but is poorly constrained by uncertainty in how the source-sink balance will evolve. Here we show that intensifying nitrogen limitation of phytoplankton, associated with near-term reductions in NPP, causes detectable declines in nitrogen isotopes (delta N-15) and constitutes the primary perturbation of the 21st century nitrogen cycle. Model experiments show that similar to 75% of the low latitude twilight zone develops anomalously low delta N-15 by 2060, predominantly due to the effects of climate change that alter ocean circulation, with implications for the nitrogen source-sink balance. Our results highlight that delta N-15 changes in the low latitude twilight zone may provide a useful constraint on emerging changes to nitrogen limitation and NPP over the 21st century. 2021 text https://www.documentation.ird.fr/hor/fdi:010083323 fdi:010083323 Buchanan P. J., Aumont Olivier, Bopp L., Mahaffey C., Tagliabue A.. Impact of intensifying nitrogen limitation on ocean net primary production is fingerprinted by nitrogen isotopes. 2021, 12 (1), 6214 [9 ] EN