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Low rates of dinitrogen fixation in the eastern tropical South Pacific
Author(s) -
Chang Bonnie X.,
Jayakumar Amal,
Widner Brittany,
Bernhardt Peter,
Mordy Calvin W.,
Mulholland Margaret R.,
Ward Bess B.
Publication year - 2019
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.1002/lno.11159
Subject(s) - photic zone , environmental chemistry , chemistry , ecology , biology , nutrient , phytoplankton
Recent work has suggested that the oxygen deficient zone (ODZ) and overlying surface waters of the eastern tropical South Pacific (ETSP) is a potential niche for dinitrogen (N 2 ) fixation. Rates of dinitrogen fixation were measured in the ETSP above and within the ODZ in July 2013 using a modified 15 N 2 bubble addition method, wherein a bubble was added, mixed, and then removed, and the isotopic enrichment of the dissolved N 2 was measured directly for each incubation. N 2 fixation rates in the euphotic zone ranged from below detection to 3.9 nmol L −1 d −1 and were below detection at all depths surveyed within the ODZ. Depth‐integrated rates ranged from below detection to 289.7 μ mol m −2 d −1 . DNA and RNA of diverse nifH genes were detected at both surface waters and in the ODZ. However, the results of this study suggest that N 2 fixation rates were low and contribute little to N cycling in the ETSP.