Ecogenomic sensor reveals controls on N2-fixing microorganisms in the North Pacific Ocean

Julie C. Robidart, Matthew J. Church, John P. Ryan, François Ascani, Samuel T. Wilson, Deniz Bombar, Roman Marin, Kelvin J. Richards, David M. Karl, Christopher A. Scholin, Jonathan P. Zehr

Research output: Contribution to journalArticlepeer-review

Abstract

Nitrogen-fixing microorganisms (diazotrophs) are keystone species that reduce atmospheric dinitrogen (N2) gas to fixed nitrogen (N), thereby accounting for much of N-based new production annually in the oligotrophic North Pacific. However, current approaches to study N2 fixation provide relatively limited spatiotemporal sampling resolution; hence, little is known about the ecological controls on these microorganisms or the scales over which they change. In the present study, we used a drifting robotic gene sensor to obtain high-resolution data on the distributions and abundances of N 2-fixing populations over small spatiotemporal scales. The resulting measurements demonstrate that concentrations of N2 fixers can be highly variable, changing in abundance by nearly three orders of magnitude in less than 2 days and 30 km. Concurrent shipboard measurements and long-term time-series sampling uncovered a striking and previously unrecognized correlation between phosphate, which is undergoing long-term change in the region, and N2-fixing cyanobacterial abundances. These results underscore the value of high-resolution sampling and its applications for modeling the effects of global change.

Original languageEnglish
Pages (from-to)1175-1185
Number of pages11
JournalISME Journal
Volume8
Issue number6
DOIs
StatePublished - Jun 2014

Keywords

  • autonomous sensing
  • biosensors
  • diazotrophs
  • microbial oceanography
  • nitrogen fixation
  • time-series

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