NATURE 388, 533-538

The role of nitrogen fixation in blogeochemical cycling in the subtropical North Pacific Ocean

D. Karl¹, R. Letelier², L. Tupas¹, J. Dore³, J. Christian⁴ & D. Hebel¹

¹School of Ocean and Earth Science and Technology, Department of 0ceanography, University of Hawaii, Honolulu, Hawaii 96822, USA

²College of 0ceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5503, USA

³Aquasearch Inc., 73-4460 Queen Kaahumanu Highway, Suite 110, Kailua-Kona, Hawaii 96740, USA

⁴Department of 0ceanography, Dalhousie University, Halifax, Nova Scotia B3H 4j1, Canada

Seven years of time-series observations of biogeochemical processes in the subtropical North Pacific Ocean gyre have revealed dramatic changes in the microbial community structure and in the mechanisms of nutrient cycling in response to large-scale ocean-atmosphere interactions. Several independent lines of evidence show that the fixation of atmospheric nitrogen by cyanobacteria can fuel up to half of the new production. These and other observations demand a reassessment of present views of nutrient and carbon cycling in one of the Earth's largest biomes.