Project: Biology and Ecology of Newly Discovered Diazotrophs in the Open Ocean

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