Vertical distributions of nitrogen-fixing phylotypes at Stn ALOHA in the oligotrophic North Pacific Ocean

In large areas of the world's oceans, biological dinitrogen (N sub(2)) fixation supports a significant fraction of ecosystem productivity; to date, however, there is little information on the abundances of specific diazotrophs in the ocean. In this study, the vertical distributions of several different groups of N sub(2)-fixing bacteria were examined using quantitative polymerase chain reaction (QPCR) amplification of group-specific dinitrogenase reductase (nifH) genes from Stn ALOHA in the subtropical North Pacific Ocean. Depth distributions (700 mu mol quanta m super(-2) s super(-1)), nitrate-depleted (