THE ROLE OF NITROGEN-FIXATION IN BIOGEOCHEMICAL CYCLING IN THE SUBTROPICAL NORTH PACIFIC-OCEAN

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