Biology and Ecology of Newly Discovered Diazotrophs in the Open Ocean
The productivity of the oceans is limited by the availability of nutrients,
which has implications for the fluxes of carbon between the atmosphere and
oceans. In a previous award the PIs found that previously unrecognized
N2-fixing unicellular cyanobacteria are active and abundant in oligotrophic
oceans. This finding has important implications for nitrogen cycling in the
oceans and for the role of "new" nitrogen in carbon fixation.
The PIs will address three major issues:
First, there are at least two distinct groups of cyanobacteria that appear
to be separated in space and time, due to unknown ecological variables.
Second, the geographic distribution and factors controlling the distribution
are unknown, so it is not clear how these organisms should be included in
biogeochemical models.
Finally, one of the groups of cyanobacteria appears to fix N2 during the day,
which revives the enigma of simultaneous nitrogen fixation and photosynthesis
that was previously limited to discussions of Trichodesmium.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Burns, J.A., Zehr, J.P., Montoya, J P, Kustka, A.B., and Capone, D. G.. "Effect of
EDTA addtiions on natural Trichodesmium spp. (CYANOPHYTA) populations," Journal of
Phycology, v.42, 2006, p. 900.
Campbell, L, E.J. Carpenter, J.P. Montoya, A.B. Kustka, D.G. Capone. "Picoplankton
community structure within and outside a Trichodesmium bloom in the southwestern
Pacific Ocean," Vie et Milieu, v.55, 2005, p. 185.
Capone, D.G., J.A. Burns, J.P. Montoya, A. Subramaniam, C. Mahaffey, T. Gunderson,
A.F. Michaels, and E.J. Carpenter. "Nitrogen fixation by Trichodesmium spp.: An
important source of new nitrogen to the tropica and subtropical North Atlantic
Ocean," Global Biogeochemical Cycles, v.19, 2005, p. doi:10.10.
Holl, C.M. & J.P. Montoya. "Interactions between nitrate uptake and nitrogen fixation
continuous cultures of the marine diazotroph Trichodesmium (Cyanophyta)," Journal of
Phycology, v.41, 2005, p. 1178.
Holl, C.M., T.A. Villareal, C.D. Payne, T.D. Clayton, C. Hart, J.P. Montoya.
"Trichodesmium in the western Gulf of Mexico: 15N2-fixation and natural abundance
stable isotope evidence," Limnology and Oceanography, v.52, 2007, p. 2249.
Holl, C.M., Waite, A.M., Pesant, S., Thompson, P, Montoya, J P. "Unicellular diazotrophy
as a source of nitrogen to Leeuwin Current coastal eddies," Deep-Sea Research I,
v.54, 2007, p. 1045.
Krauk, J.M, T.A. Villareal, J.A. Sohm, J.P. Montoya, and D.G. Capone. "Plasticity
of N:P ratios in laboratory and field populations of Trichodesmium spp.," Aquatic
Microbial Ecology, v.72, 2006, p. 243.
Montoya, J P, Holl, C.M., Zehr, J.P., Hansen, A., Villareal, T.A., Capone, D.G..
"High rates of N2-fixation by unicellular diazotrophs in the oligotrophic Pacific,"
Nature, v.430, 2004, p. 1027.
Montoya, J.P., M. Voss, and D.G. Capone. "Spatial variation in N2-fixation rate
and diazotroph activity in the Tropical Atlantic," Biogeosciences, v.4, 2007, p. 396.
Subramaniam, A, P.L. Yager, E.J. Carpenter, C. Mahaffey, K. Bjorkman, S. Cooley,
A. Kustka, J.P. Montoya, A. Sañudo-Wilhelmy, R. Shipe, and D.G. Capone. "Amazon River
enhances diazotrophy and carbon sequestration in the tropical North Atlantic Ocean,"
Proc. Natl. Acad. Sci, v.105, 2008, p. 10460.
Waite, AM; Muhling, BA; Holl, CM; Beckley, LE; Montoya, JP; Strzelecki, J; Thompson, PA;
Pesant, S. "Food web structure in two counter-rotating eddies based on delta N-15 and
delta C-13 isotopic analyses," DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY,
v.54, 2007, p. 1055-1075. View record at Web of Science
Principal Investigator: Jonathan P. Zehr
University of California-Santa Cruz (UCSC)
Co-Principal Investigator: Matthew J. Church
University of Hawaiʻi at Mānoa (SOEST)
Co-Principal Investigator: Joseph Montoya
Georgia Institute of Technology (GA Tech)