Sources of iron and phosphate affect the distribution of diazotrophs in the North Atlantic
Name
boyle DeepSeaResearchII - full manucript penultimate draft.pdf
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1.43 MB
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Checksum (MD5)
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Author(s)
Ratten, Jenni-Marie
LaRoche, Julie
Desai, Dhwani K.
Shelley, Rachel U.
Landing, William M.
Cutter, Gregory A.
Langlois, Rebecca J.
Boyle, Edward A
Date Issued
June 2015
Journal
Deep Sea Research Part II: Topical Studies in Oceanography
Publisher
Elsevier
Citation
Ratten, Jenni-Marie, Julie LaRoche, Dhwani K. Desai, Rachel U. Shelley, William M. Landing, Ed Boyle, Gregory A. Cutter, and Rebecca J. Langlois. “Sources of Iron and Phosphate Affect the Distribution of Diazotrophs in the North Atlantic.” Deep Sea Research Part II: Topical Studies in Oceanography 116 (June 2015): 332–341.
Version
Original manuscript
Abstract
Biological nitrogen fixation (BNF) supplies nutrient-depleted oceanic surface waters with new biologically available fixed nitrogen. Diazotrophs are the only organisms that can fix dinitrogen, but the factors controlling their distribution patterns in the ocean are not well und erstood. In this study, the relative abundances of eight diazotrophic phylotypes in the subtropical North Atlantic Ocean were determined by quantitative PCR (qPCR) of the nifH gene using TaqMan probes. A total of 152 samples were collected at 27 stations during two GEOTRACES cruises; Lisbon, Portugal to Mindelo, Cape Verde Islands (USGT10) and Woods Hole, MA, USA via the Bermuda Time Series (BATS) to Praia, Cape Verde Islands (USGT11). Seven of the eight diazotrophic phylotypes tested were detected. These included free-li ving and symbiotic cyanobacteria (unicellular groups (UCYN) A, B and C, Trichodesmium , the diatom-associated cyanobacteria Rhizoselinia–Richelia and Hemiaulus–Richelia and γ-proteobacterium (Gamma A, AY896371). The nifH gene abundances were analyzed in the context of a large set of hydrographic parameters, macronutrient and trace metal concentrations measured in parallel with DNA samples using the PRIMER-E software. The environmental variables that most in fluenced the abundances and distribution of the diazotrophic ph ylotypes were determined. We observed a geographic segregation of diazotrophic phylotypes between east and west, with UCYN A, UCYN B and UCYN C and the Rhizosolenia–Richelia symbiont associated with the eastern North Atlantic (east of 40°W), and Trichodesmium and Gamma A detected across the basin .Hemiaulus–Richelia symbionts were primarily found in temperate waters near the North American coast. The highest diazotrophic phylotype abundance and diversity were associated with temperatures greater than 22 °C in the surface mixed layer, a high supply of iron from North African aeolian mineral dust deposition and from remi neralized nutrients upwelled at the edge of the oxygen minimum zone off the north western coast of Africa.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Creative Commons Attribution-NonCommercial-NoDerivs License
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DOI of Published Version
https://doi.org/10.1016/j.dsr2.2014.11.012
