Oligotrophic ocean

Owens, N.J.E, Galloway, J.N. and Duce, R.A. (1992) Episodic atmospheric nitrogen deposition to oligotrophic oceans. Nature, 357, 397-399. 

Clark, D. R., Pileman, T. W., and Joint, I. (2006). Determination of ammonium regeneration rates in the oligotrophic ocean by gas chromatograpy/mass spectrometry. Mar. Chem. 98, 121—130. 

Meador, T. B., Aluwihare, L. I., and Mahaffey, C. (2007). Isotopic heterogeneity and cycling of components of the dissolved organic nitrogen pool in the oligotrophic ocean. Limnology and Oceanography 52(3), 934—947. 

Zehr, J. P., Mellon, M. T., and Zani, S. (1998). New nitrogen-fixing microorganisms detected in oligotrophic oceans by the amplification of nitrogenase (nifH) genes. Appl. Environ. Microbiol. 64, 3444-3450. 

Figure 7.1 Classical and current views of the N cycle in the surface waters of oligotrophic oceans. The composition of the dissolved N pool is shown with approximate relative concentrations of inorganic and organic constituents indicated hy the sizes of the boxes. Dashed lines indicate transformations and processes included in the newer view of N cycling. (A) Some phytoplankton use simple and more complex organic compounds as a source of N and phytoplankton can he sources of inorganic and organic N as well. (B) There are multiple species of phytoplankton (cyanobacteria) in the open ocean that fix N2. (C) Bacteria compete for NOs and NH4+. (D) Bacteria can take up and excrete urea and also be a source of DON. (E) Some oceanic bacterioplankton appear to fix N2 (modified from Zehr and Ward, 2002).

Zubkov, M. V., Fuchs, B. M., Tarran, G. A., Burkill, P. H., and Amann, R. (2003). High rate of uptake of organic nitrogen compounds by Prochlorococcus cyanobacteria as a key to their dominance in oligotrophic oceanic waters. Appl. Environ. Microbiol. 69, 1299—1304. 

Hewson, I., Govil, S. R., Capone, D. G., Carpenter, E. J., and Puhrman, J. A. (2004). Evidence of Trichodesmium viral lysis and potential significance for biogeochemical cycling in the oligotrophic ocean. Aquat. Microb. Ecol. 36, 1-8. 

An interesting result of open ocean nutrient limitation/enrichment research is the discovery that primary production in certain oligotrophic ocean gyres (Northern and... 

Lipschultz, F., Zafiriou, O. C., andBaU, L. A. (1996). Seasonal fluctuations of nitrite concentrations in the deep oligotrophic ocean. Deep Sea Res. II43, 403—419. 

Processes in Oligotrophic Oceans primary production plankton community size distributions ... 

Nutrients are often the key limiting factors to primary production in the tropical seas, and symbioses are frequently observed in these types of oligotrophic habitats. From his many microscopy observations, Norris (1967) speculated that a considerable part of the biota in the open ocean were involved at one time or another in a consortium, either temporary or more permanent. Forming a symbiotic association might then be considered an ecological adaptation to life in the oligotrophic ocean. 

Falcon et al. (2005) examined the P04 requirements of Atlantic and Pacific unicellular diazotrophic cyanobacteria isolates, and found that half-saturation constants for growth ranged from 0.06 to 0.25 pM. These are similar to the growth halfsaturation constants of 0.14-0.22 pM reported for Trichodesmium by Fu et al. (2005b), suggesting that these unicellular N2-fixers would also be quite unhkely to meet their cellular P demands by relying on P04 at the reported concentrations in the oligotrophic oceans ( 5-40 nM, Table 38.1). 

Other studies showed that the oligotrophic ocean areas are dominated by phytoplankton organisms of relatively small size, generally less than 5 jLtm. Therefore, the spectral signatures of the oligotrophic small cell size populations should resemble that of the blue water population, and the eutrophic populations typical of coastal and upwelling regions, which gen-... 

Venrick E.L. (1982) Phytoplankton in an oligotrophic ocean observations and questions. Ecol. Monogr. 52, 129-54. 

Berman, T., Azov, Y. and Townsend, D.W. (1984) Understanding oligotrophic oceans can the eastern Mediterranean be a useful model, in Marine phytoplankton and productivity (eds O. Holm Hansen, L. Bolis and R. Gillies), Springer-Verlag, Berlin, pp. 101-112. 

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