Chemoautotrophic activity and nitrification in the oxygen minimum zone off Peru

B. B. Ward, H. E. Glover, F. Lipschultz

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The oxygen minimum zone off Peru is the site of intense nitrogen cycling, driven by the large input of organic material from highly productive overlying waters. Using three independent experimental methods, we assessed chemoautotrophic activity and nitrification rates in depth profiles through the oxygen gradient and minimum regions. Nitrifying bacteria (both ammonium and nitrite oxidizers) were present throughout the oxygen minimum zone. Even in very low oxygen waters, in situ chemoautotrophic activity and nitrogen oxidation were commonly detected. Highest abundance of nitrifying bacteria and highest activities were found in the gradient region at the upper boundary of the oxygen minimum. Due to the occurrence of strong minima and maxima in the distributions of many parameters, activities were not linearly correlated with environmental and chemical variables. The data are consistent with close coupling between nitrification and denitrification in the oxygen minimum zone, and rapid cycling of nitrogen cycle intermediates including nitrate, nitrite and nitrous oxide.

Original languageEnglish (US)
Pages (from-to)1031-1051
Number of pages21
JournalDeep Sea Research Part A, Oceanographic Research Papers
Issue number7
StatePublished - Jul 1989
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Environmental Science
  • General Earth and Planetary Sciences


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