Natural Abundance of 15N in Marine Planktonic Ecosystems

Stable Isotopes in Ecology and Environmental Science: Second Edition

Volumn , Issue , 2008, Pages 176-201

  Montoya, Joseph P ^a  

^a GEORGIA INSTITUTE OF TECHNOLOGY   (United States)

Author keywords

Isotopic fractionation; Isotopic variation; Planktonic ecosystem; Residual substrate; Source delineation

Indexed keywords

ISOTOPES;

ISOTOPIC FRACTIONATIONS; ISOTOPIC VARIATIONS; NATURAL ABUNDANCE; SOURCE DELINEATION;

ECOSYSTEMS;

EID: 84889406557     PISSN: None     EISSN: None     Source Type: Book    
DOI: 10.1002/9780470691854.ch7     Document Type: Chapter

References (115)

1. Altabet, M.A. & François, R. (1994) Sedimentary nitrogen isotopic ratio records surface ocean nitrate utilization. Global Biogeochemical Cycles, 8, 103-116.
2. Altabet, M.A. & Small, L.F. (1990) Nitrogen isotopic ratios in fecal pellets produced by marine zooplankton. Geochimica et Cosmochimica Acta, 54, 155-163.
3. Altabet, M.A., Deuser, W.G., Honjo, S. & Stienen, C. (1991) Seasonal and depth-related changes in the source of sinking particles in the North Atlantic. Nature, 354, 136-139.
4. 14N ratios. Nature, 373, 506-509.
5. Bada, J.L., Schoeninger, M.J. & Schimmelmann, A. (1989) Isotopic fractionation during peptide bond hydrolysis. Geochimica et Cosmochimica Acta, 53, 3337-3341.
6. 2O production in Paracoccus denitrificans. Applied and Environmental Microbiology, 65, 989-994.
7. Brandes, J.A. & Devol, A.H. (1997) Isotopic fractionation of oxygen and nitrogen in coastal marine sediments. Geochimica et Cosmochimica Acta, 61, 1793-1801.
8. Brandes, J.A. & Devol, A.H. (2002) A global marine fixed nitrogen isotopic budget: Implications for Holocene nitrogen cycling. Global Biogeochemical Cycles, 16, 1120, doi:10.1029/2001GB001856.
9. Brandes, J.A., Devol, A.H., Yoshinari, T., Jayakumar, D.A. & Naqvi, S.W.A. (1998) Isotopic composition of nitrate in the central Arabian Sea and eastern tropical North Pacific: A tracer for mixing and nitrogen cycles. Limnology and Oceanography, 43, 1680-1689.
10. Capone, D.G., Subramanian, A., Montoya, J.P., et al. (1998) An extensive bloom of the N2-fixing cyanobacterium, Trichodesmium erythraeum, in the central Arabian Sea during the spring intermonsoon. Marine Ecology Progress Series, 172, 281-292.
11. Capone, D.G., Burns, J.A., Montoya, J.P., et al. (2005) Nitrogen fixation by Trichodesmium spp.: an important source of new nitrogen to the tropical and subtropical North Atlantic Ocean. Global Biogeochemical Cycles, 19, GB2024, doi:10.1029/2004GB002331.
12. Carpenter, E.J., Harvey, H.R., Fry, B. & Capone, D.G. (1997) Biogeochemical tracers of the marine cyanobacterium Trichodesmium. Deep-Sea Research, 44, 27-38.
13. Carpenter, E.J., Montoya, J.P., Burns, J., Mulholland, M., Subramanian, A. & Capone, D.G. (1999) Extensive bloom of a N2-fixing symbiotic association (Hemiaulis hauckii and Richelia intracellularis) in the tropical Atlantic Ocean. Marine Ecology Progress Series, 188, 273-283.
14. Checkley, D.M. & Entzeroth, L.C. (1985) Elemental and isotopic fractionation of carbon and nitrogen by marine, planktonic copepods and implications to the marine nitrogen cycle. Journal of Plankton Research, 7, 553-568.
15. Checkley, D.M., Jr. & Miller, C.A. (1989) Nitrogen isotope fractionation by oceanic zooplankton. Deep-Sea Research, 36, 1449-1456.
16. Church, M.J., Jenkins, B.D., Karl, D.M. & Zehr, J.P. (2005) Vertical distributions of nitrogen-fixing phylotypes at Station ALOHA in the oligotrophic North Pacific Ocean. Aquatic Microbial Ecology, 38, 3-14.
17. Cifuentes, L.A., Sharp, J.H. & Fogel, M.L. (1988) Stable carbon and nitrogen isotope biogeochemistry in the Delaware estuary. Limnology and Oceanography, 33, 1102-1115.
18. Cifuentes, L.A., Fogel, M.L., Pennock, J.R. & Sharp, J.H. (1989) Biogeochemical factors that influence the stable nitrogen isotope ratio of dissolved ammonium in the Delaware Estuary. Geochimica et Cosmochimica Acta, 53, 2713-2721.
19. Cline, J.D. & Kaplan, I.R. (1975) Isotopic fractionation of dissolved nitrate during denitrifi -cation in the eastern tropical North Pacific Ocean. Marine Chemistry, 3, 271-299.
20. Codispoti, L.A., Brandes, J.A., Christensen, J.P., et al. (2001) The oceanic fixed nitrogen and nitrous budgets: moving targets as we enter the Anthropocene? Scientia Marina, 65, 85-105.
21. Delwiche, C.C. & Steyn, P.L. (1970) Nitrogen isotope fractionation in soils and microbial reactions. Environmental Science and Technology, 4, 929-935.
22. DeNiro, M.J. & Epstein, S. (1981) Influence of diet on the distribution of nitrogen isotopes in animals. Geochimica et Cosmochimica Acta, 45, 341-351.
23. Deutsch, C., Gruber, N., Key, R.M. & Sarmiento, J.L. (2001) Denitrification and N2 fixation in the Pacific Ocean. Global Biogeochemical Cycles, 15, 483-506.
24. Dore, J.E., Brum, J.R., Tupas, L. & Karl, D.M. (2002) Seasonal and interannual variability in sources of nitrogen supporting export in the oligotrophic subtropical North Pacific Ocean. Limnology and Oceanography, 47, 1595-1607.
25. Falcon, L.I., Carpenter, E.J., Cipriano, F., Bergman, B. & Capone, D.G. (2004) N2 fixation by unicellular bacterioplankton from the Atlantic and Pacific Oceans: Phylogeny and in situ rates. Applied and Environmental Microbiology, 70, 765-770.
26. Fantle, M.S., Dittel, A.I., Schwalm, S.M., Epifanio, C.E. & Fogel, M.L. (1999) A food web analysis of the juvenile blue crab, Callinectes sapidus, using stable isotopes in whole animals and individual amino acids. Oecologia, 120, 416-426.
27. Frazer, T.K., Ross, R.M., Quetin, L.B. & Montoya, J.P. (1997) Turnover of carbon and nitrogen during growth of larval krill, Euphausia superba: a stable isotope approach. Journal of Experimental Marine Biology and Ecology, 212, 259-275.
28. Fry, B. (1988) Food web structure on Georges Bank from stable C, N, and S isotopic compositions. Limnology and Oceanography, 33, 1182-1190.
29. Galloway, J.N., Howarth, R.W., Michaels, A.F., Nixon, S.W., Prospero, J.M. & Dentener, F.J. (1996) Nitrogen and phosphorus budgets of the North Atlantic Ocean and its watershed. Biogeochemistry, 35, 3-25.
30. Ganeshram, R.S., Pedersen, T.F., Calvert, S.E. & Murray, J.W. (1995) Large changes in oceanic nutrient inventories from glacial to interglacial periods. Nature, 376, 755-758.
31. Gannes, L.Z., O'brien, D.M. & Martinez Del Rio, C. (1997) Stable isotopes in animal ecology: Assumptions, caveats, and a call for more laboratory experiments. Ecology, 78, 1271-1276.
32. Goering, J., Alexander, V. & Haubenstock, N. (1990) Seasonal variability of stable carbon and nitrogen isotopic ratios of organisms in a North Pacific bay. Estuarine, Coastal and Shelf Science, 30, 239-260.
33. 2. In: Carbon-Climate Interactions (Eds M. Follows & T. Oguz), pp. 97-148. Kluwer Academic, Dordrecht.
34. Gruber, N. & Sarmiento, J.L. (1997) Global patterns of marine nitrogen fixation and denitrification. Global Biogeochemical Cycles, 11, 235-266.
35. Hare, P.E., Fogel, M.L., Stafford, T.W., Jr., Mitchell, A.D. & Hoering, T.C. (1991) The isotopic composition of carbon and nitrogen in individual amino acids isolated from modern and fossil proteins. Journal of Archaeological Science, 18, 277-292.
36. Heaton, T.H.E. (1986) Isotopic studies of nitrogen pollution in the hydrosphere and atmosphere: a review. Chemical Geology (Isotope Geoscience Section), 59, 87-102.
37. Hoering, T. (1955) Variations of nitrogen-15 abundance in naturally occurring substances. Science, 122, 1233-1234.
38. Hoering, T.C. & Ford, H.T. (1960) The isotope effect in the fixation of nitrogen by Azotobacter. Journal of the American Chemical Society, 82, 376-378.
39. Holmes, M.E., Muller, P.J., Schneider, R.R., Segl, M., Patzold, J. & Wefer, G. (1996a) Stable nitrogen isotopes in Angola Basin surface sediments. Marine Geology, 134, 1-12.
40. Holmes, M.E., Müller, P.J., Schneider, R.R., Segl, M., Pötzold, J. & Wefer, G. (1996b) Stable nitrogen isotopes in Angola Basin surface sediments. Marine Geology, 134, 1-12.
41. 15N in sinking particles in the Benguela Upwelling Region. Deep-Sea Research Part I, 49, 377-394.
42. Karl, D.M., Christian, J.R., Dore, J.E., et al. (1996) Seasonal and interannual variability in primary production and particle flux at Station ALOHA. Deep-Sea Research Part II, 43, 539-568.
43. Karl, D., Letelier, R., Tupas, L., Dore, J., Christian, J. & Hebel, D. (1997) The role of nitrogen fixation in biogeochemical cycling in the subtropical North Pacific Ocean. Nature, 388, 533-538.
44. Knap, A.N., Sigman, D.M. & Lipschultz, F. (2005) N isotopic composition of dissolved organic nitrogen and nitrate at the Bermuda Atlantic Time-series Study site. Global Biogeochemical Cycles, 19, doi:10.1029/2004GB002320,doi:10.1029/2004GB002320.
45. Lee, K., Karl, D.M., Wanninkhof, R.H. & Zhang, J.Z. (2002) Global estimates of net carbon production in the nitrate-depleted tropical and subtropical oceans. Geophysical Research Letters, 29, doi:10.1029/2001GLO14198.
46. 15N-enriched nitrate in seawater off southern California. Limnology and Oceanography, 34, 820-830.
47. Macko, S.A. & Uhle, M.E. (1997) Stable nitrogen isotope analysis of amino acid enantiomers by gas chromatography/combustion/isotope ratio mass spectrometry. Analytical Chemistry, 69, 926-929.
48. Macko, S.A., Entzeroth, L. & Parker, P.L. (1984) Regional differences in nitrogen and carbon isotopes on the continental shelf of the Gulf of Mexico. Naturwissenschaften, 71, 374-375.
49. Macko, S.A., Fogel Estep, M.L., Engel, M.H. & Hare, P.E. (1986) Kinetic fractionation of stable nitrogen isotopes during amino acid transamination. Geochimica et Cosmochimica Acta, 50, 2143-2146.
50. Macko, S.A., Fogel, M.L., Hare, P.E. & Hoering, T.C. (1987) Isotopic fractionation of nitrogen and carbon in the synthesis of amino acids by microorganisms. Chemical Geology (Isotope Geoscience Section), 65, 79-92.
51. Mariotti, A., Germon, J.C., Hubert, P., et al. (1981) Experimental determination of nitrogen kinetic isotope fractionation: some principles; illustration for the denitrification and nitrification processes. Plant and Soil, 62, 413-430.
52. Mariotti, A., Germon, J.C., Leclerc, A., Catroux, G. & Letolle, R. (1982) Experimental determination of kinetic isotopic fractionation of nitrogen isotopes during denitrification. In: Stable Isotopes (Eds H.-L. Schmidt, H. Forstel & K. Heinzinger), pp. 459-464. Elsevier, Amsterdam.
53. McClelland, J.W. & Montoya, J.P. (2002) Trophic relationships and the nitrogen isotopic composition of amino acids in plankton. Ecology, 83, 2173-2180.
54. McClelland, J.W. & Valiela, I. (1998a) Changes in food web structure under the influence of increased anthropogenic nitrogen inputs to estuaries. Marine Ecology Progress Series, 168, 259-271.
55. McClelland, J.W. & Valiela, I. (1998b) Linking nitrogen in estuarine producers to landderived sources. Limnology and Oceanography, 43, 577-585.
56. McClelland, J.W., Holl, C.M. & Montoya, J.P. (2003) Nitrogen sources to zooplankton in the Tropical North Atlantic: Stable isotope ratios of amino acids identify strong coupling to N2-fixation. Deep-Sea Research Part I, 50, 849-861.
57. 4 by Desulfovibrio sp. Canadian Journal of Microbiology, 29, 231-234.
58. 14N isotopic composition in individual plasma free amino acids of human adults at natural abundance by gas chromatography-combustion isotope ratio mass spectrometry. Analytical Biochemistry, 247, 158-164.
59. 15N isotopic abundances in physiological samples: a pilot study on amino acid synthesis in the upper gastro-intestinal tract of minipigs. Journal of Mass Spectrometry, 31, 367-376.
60. Michaels, A.F., Olson, D., Sarmiento, J., et al. (1996) Inputs, losses and transformation of nitrogen and phosphorus in the deep North Atlantic Ocean. Biogeochemistry, 35, 181-226.
61. Mills, M.M., Ridame, C., Davey, M., La Roche, J. & Geider, R.J. (2004) Iron and phosphorus co-limit nitrogen fixation in the eastern tropical North Atlantic. Nature, 429, 292-294.
62. 15N and animal age. Geochimica et Cosmochimica Acta, 48, 1135-1140.
63. 14N in marine environments. Records of Oceanographic Works in Japan, 9, 37-53.
64. Miyake, Y. & Wada, E. (1971) The isotope effect on the nitrogen in biochemical oxidation-reduction reactions. Records of Oceanographic Works in Japan, 11, 1-6.
65. Montoya, J.P. & McCarthy, J.J. (1995) Nitrogen isotope fractionation during nitrate uptake by marine phytoplankton in continuous culture. Journal of Plankton Research, 17, 439-464.
66. Montoya, J.P. & Voss, M. (2006) Nitrogen cycling in suboxic waters: Isotopic signatures of nitrogen transformations in the Arabian Sea Oxygen Minimum Zone. In: Past and Present Water Column Anoxia (Ed. L. Neretin), pp. 259-281. Springer-Verlag, Dordrecht.
67. 15N in particulate nitrogen and zooplankton in the Chesapeake Bay. Marine Ecology Progress Series, 65, 35-61.
68. 15N in a planktonic ecosystem. Geochimica et Cosmochimica Acta, 55, 3627-3638.
69. 15N in particulate nitrogen and zooplankton in the Gulf Stream region and Warm-Core Ring 86A. Deep-Sea Research, 39(Supplement 1), S363-S392.
70. Montoya, J.P., Carpenter, E.J. & Capone, D.G. (2002) Nitrogen-fixation and nitrogen isotope abundances in zooplankton of the oligotrophic North Atlantic. Limnology and Oceanography, 47, 1617-1628.
71. Montoya, J.P., Holl, C.M., Zehr, J.P., Hansen, A., Villareal, T.A. & Capone, D.G. (2004) High rates of N2-fixation by unicellular diazotrophs in the oligotrophic Pacific. Nature, 430, 1027-1031.
72. Mullin, M.M., Rau, G.H. & Eppley, R.W. (1984) Stable nitrogen isotopes in zooplankton: some geographic and temporal variations in the North Pacific. Limnology and Oceanography, 29, 1267-1273.
73. Nakatsuka, T., Handa, N., Wada, E. & Wong, C.S. (1992) The dynamic changes of stable isotope ratios of carbon and nitrogen in suspended and sedimented particulate organic matter during a phytoplankton bloom. Journal of Marine Research, 50, 267-296.
74. 3-, and nitrogen isotope fractionation by marine phytoplankton. Journal of Phycology, 40, 505-516.
75. Needoba, J.A., Waser, N.A.D., Harrison, P.J. & Calvert, S.E. (2003) Nitrogen isotope fractionation by 12 species of marine phytoplankton during growth on nitrate. Marine Ecology Progress Series, 255, 81-91.
76. Nixon, S.W., Ammerman, J.W., Atkinson, L.P., et al. (1996) The fate of nitrogen and phosphorus at the land-sea margin of the North Atlantic Ocean. Biogeochemistry, 35, 141-180.
77. Ostrom, N.E., Macko, S.A., Deibel, D. & Thompson, R.J. (1997) Seasonal variation in the stable carbon and nitrogen isotope biogeochemistry of a coastal cold environment. Geochimica et Cosmochimica Acta, 61, 2929-2942.
78. Paerl, H.W. & Fogel, M.L. (1994) Isotopic characterization of atmospheric nitrogen inputs as sources of enhanced primary production in coastal Atlantic Ocean waters. Marine Biology, 119, 635-645.
79. Pakhomov, E.A., Mcclelland, J., Bernard, K., Kaehler, S. & Montoya, J.P. (2004) Spatial and temporal shifts in stable isotope values of the bottom-dwelling shrimp Nauticaris marionis at the sub-Antarctic archipelago. Marine Biology, 144, 317-325.
80. -by Skeletonema costatum. Eos, 69, 1098.
81. Pennock, J.R., Velinsky, D.J., Ludlam, J.M., Sharp, J.H. & Fogel, M.L. (1996) Isotopic fractionation of ammonium and nitrate during uptake by Skeletonema costatum: Implications for delta N-15 dynamics under bloom conditions. Limnology and Oceanography, 41, 451-459.
82. Prospero, J.M., Barrett, K., Church, T., et al. (1996) Atmospheric deposition of nutrients to the North Atlantic Basin. Biogeochemistry, 35, 27-73.
83. 15N, and D abundance between a polluted and an unpolluted coastal site: likely indicators of sewage uptake by a marine food web. Estuarine, Coastal and Shelf Science, 13, 701-707.
84. Russell, K.M., Galloway, J.N., Macko, S.A., Moody, J.L. & Scudlark, J.R. (1998) Sources of nitrogen in wet deposition ot the Chesapeake Bay region. Atmospheric Envionment, 32, 2453-2465.
85. 15N natural abundance in oceanic suspended particulate matter. Nature, 283, 752-754.
86. 15N natural abundance in the Pacific and its marginal seas. Deep-Sea Research, 34, 807-827.
87. Schlacher, T.A., Liddell, B., Gaston, T.F. & Schlacher-Hoenlinger, M. (2005) Fish track wastewater pollution to estuaries. Oecologia, 144, 570-584.
88. 15N values: Implications of tissue-specific fractionation and amino acid composition. Marine Ecology Progress Series, 266, 43-58.
89. Sheats, N. (2000) The use of stable isotopes to define the extent of incorporation of sewage nitrogen into aquatic foodwebs and to discern differences in habitat suitability within a single estuary. Dissertation, Department of Earth and Planetary Sciences, Harvard University. Cambridge, MA, 278 pp.
90. Sigman, D.M., Altabet, M.A., Michener, R., McCorkle, D.C. & François, R. (1996) A new method for the nitrogen isotopic analysis of oceanic nitrate and first results from the Southern Ocean. Eos, 76, 143.
91. Sigman, D.M., Altabet, M.A., Michener, R., McCorkle, D.C., Fry, B. & Holmes, R.M. (1997) Natural abundance-level measurment of the nitrogen isotopic composition of oceanic nitrate: an adaptation of the ammonia diffusion method. Marine Chemistry, 57, 227-242.
92. 15N of nitrate in the Southern Ocean: Comsumption of nitrate in surface waters. Global Biogeochemical Cycles, 13, 1149-1166.
93. 15N of nitrate in the Southern Ocean: Nitrogen cycling and circulation in the ocean interior. Journal of Geophysical Research, 105, 19599-19614.
94. Spies, R.B., Kruger, H., Ireland, R. & Rice, D.W., Jr. (1989) Stable isotope ratios and contaminant concentrations in a sewage-distorted food web. Marine Ecology Progress Series, 54, 157-170.
95. Sutka, R.L., Ostrom, N.E., Ostrom, P.H. & Phanikumar, M.S. (2004) Stable nitrogen isotope dynamics of dissolved nitrate in a transect from the North Pacific Subtropical Gyre to the Eastern Tropical North Pacific. Geochimica et Cosmochimica Acta, 68, 517-527.
96. Sweeney, R.E., Liu, K.K. & Kaplan, I.R. (1978) Oceanic nitrogen isotopes and their uses in determing the sources of sedimentary nitrogen. In: Stable Isotopes in the Earth Sciences (Ed. B. W. Robinson), pp 9-26. Bulletin 220, Department of Scientific and Industrial Research, Wellington.
97. Sweeney, R.E., Kalil, E.K. & Kaplan, I.R. (1980) Characterisation of domestic and industrial sewage in southern California coastal sediments using nitrogen, carbon, sulphur, and uranium tracers. Marine Environmental Research, 3, 225-243.
98. Tucker, J.N., Sheats, N., Giblin, A.E., Hopkinson, C.S. & Montoya, J.P. (1999) Using stable isotopes to trace sewage derived material through Boston Harbor and Massachusetts Bay. Marine and Environmental Research, 48, 353-375.
99. Uhle, M.E., Macko, S.A., Spero, H.J., Engel, M.H. & Lea, D.W. (1997) Sources of carbon and nitrogen in modern planktonic foraminifera: the role of algal symbionts as determined by bulk compound specific stable isotopic analysis. Organic Geochemistry, 27, 103-113.
100. Van Dover, C.L., Grassle, J.F., Fry, B., Garritt, R.H. & Starczak, V.R. (1992) Stable isotope evidence for entry of sewage-derived organic material into a deep-sea food web. Nature, 360, 153-155.
101. Voss, M. & Struck, U. (1997) Stable nitrogen and carbon isotopes as indicator of eutrophication of the Oder river (Baltic sea). Marine Chemistry, 59, 35-49.
102. Voss, M., Dippner, J. & Montoya, J.P. (2001) Nitrogen isotope patterns in the oxygen deficient waters of the Eastern Tropical North Pacific (ETNP). Deep-Sea Research, 48, 1905-1921.
103. Voss, M., Croot, P., Lochte, K., Mills, M. & Peeken, I. (2004) Patterns of nitrogen fixation along 10°N in the tropical Atlantic. Geophysical Research Letters, 31, doi:10.1029/2004GL020127.
104. Wada, E. (1980) Nitrogen isotope fractionation and its significance in biogeochemical processes occurring in marine environments. In: Isotope Marine Chemistry (Eds E. Goldberg, Y. Horibe & K. Saruhashi), pp. 375-398. Uchida Rokakuho, Tokyo.
105. 15N in particulate organic matter in the North Pacific Ocean. Geochimica et Cosmochimica Acta, 40, 249-251.
106. Wada, E. & Hattori, A. (1978) Nitrogen isotope effects in the assimilation of inorganic nitrogenous compounds. Geomicrobiology Journal, 1, 85-101.
107. Wada, E. & Hattori, A. (1991) Nitrogen in the Sea: Forms, Abundances, and Rate Processes. CRC Press, Boca Raton, FL.
108. 15N abundance in nitrogen of naturally occurring substances and global assessment of denitrification from isotopic viewpoint. Geochemical Journal, 9, 139-148.
109. 13C abundances in the Antarctic Ocean with emphasis on biogeochemical structure of the food web. Deep-Sea Research, 34, 829-841.
110. Waser, N.A., Yin, K., Yu, Z., et al. (1998a) Nitrogen isotope fractionation during nitrate, ammonium and urea uptake by marine diatoms and coccolithophores under various conditions of N availability. Marine Ecology Progress Series, 169, 29-41.
111. Waser, N.A.D., Harrison, P.J., Nielsen, B., Calvert, S.E. & Turpin, D.H. (1998b) Nitrogen isotope fractionation during the uptake and assimilation of nitrate, nitrite, ammonium, and urea by a marine diatom. Limnology and Oceanography, 43, 215-224.
112. Wu, J.P., Calvert, S.E. & Wong, C.S. (1999) Carbon and nitrogen isotope ratios in sedimenting particulate organic matter at an upwelling site off Vancouver Island. Estuarine Coastal and Shelf Science, 48, 193-203.
113. 2O as a product of nitrification. Nature, 335, 528-529.
114. Zehr, J.P., Mellon, M.T. & Zani, S. (1998) New nitrogen-fixing microorganisms detected in oligotrophic oceans by amplification of nitrogenase (nifH) genes. Applied and Environmental Microbiology, 64, 3444-3450.
115. Zehr, J.P., Waterbury, J.B., Turner, P.J., et al. (2001) New nitrogen-fixing unicellular cyanobacteria discovered in the North Pacific Central Gyre. Nature, 412, 635-638.