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Airborne Microbes Contribute to N 2 Fixation in Surface Water of the Northern Red Sea
Author(s) -
Rahav Eyal,
Paytan Adina,
Mescioglu Esra,
Galletti Yuri,
Rosenfeld Sahar,
Raveh Ofrat,
Santinelli Chiara,
Ho TungYuan,
Herut Barak
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl077132
Subject(s) - diazotroph , mesocosm , environmental chemistry , nutrient , deposition (geology) , environmental science , nitrogen fixation , aerosol , trichodesmium , biology , chemistry , ecology , bacteria , sediment , genetics , paleontology , organic chemistry
Desert dust storms are frequent in the Northern Red Sea region, providing nutrients (i.e., PO 4 ) and trace‐metals (i.e., Fe) that may stimulate dinitrogen (N 2 ) fixation. Dust also carries a high diversity of airborne microbes (bacteria and archaea), including diazotrophs, that may remain viable during transport and upon deposition. Here we evaluate the impact of atmospheric deposition and its associated airborne diazotrophs on N 2 fixation in the surface water of the low‐nutrient Northern Red Sea, using mesocosm bioassay experiments. We compared the chemical (nutritional) and sole airborne microbial impact of aerosol additions on N 2 fixation using “live‐dust” (release nutrients/trace metals and viable airborne microorganisms) and “UV‐killed dust” (release only chemicals). Airborne diazotrophy accounted for about one third of the measured N 2 fixation (0.35 ± 0.06 nmol N · L −1 · day −1 and 0.29 ± 0.06 nmol N · L −1 · day −1 , for “February 2017” and “May 2017,” “live‐dust” additions, respectively). Two nifH sequences related to cluster III diazotrophs were amplified from the dust samples, consistent with the N 2 fixation measurement results. We postulate that the deposition of viable airborne diazotrophs may enhance N 2 fixation, especially in marine provinces subjected to high aerosol loads. We speculate that the relative contribution of airborne N 2 fixation may increase in the future with the predicted increase in dust deposition.