Phytoplankton nitrate uptake

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Falkowski, P.G. (1975) Nitrate uptake in marine phytoplankton (Nitrate, chloride)-activated adenosine triphosphate from Skeletonema costatum (Bacillariophyceae). J. Phycol. 11, 323-326. 

CoUos, Y., and Slawyk, G. (1986). C and N uptake by marine phytoplankton. IV. Uptake ratios and the contribution of nitrate to the productivity of Antarctic waters (Indian Ocean sector). Deep Sea Res. 133, 1039-1051. 

CoUos, Y., Vaquer, A., Bibent, B., Slawyk, G., Cagcia, N., and Souchu, P. (1997). Variability in nitrate uptake kinetics of phytoplankton communities in a Mediterranean coastal lagoon. Estuar. Coast. 

Dortch, Q., Clayton, R. A., Thoresen, S., Bressler, S., and Ahmed, S. (1982). Response of marine phytoplankton to nitrogen deficiency Decreased nitrate uptake vs. enhanced ammonium uptake. Mar. Biol. 70, 13-19. 

Eppley, R. W., and Thomas, W. H. (1969). Comparison of half-saturation constants for growth and nitrate uptake of marine phytoplankton. J. Phycol. 5, 375—379. 

Hu, S. H., and Smith, W. O. (1998). The effects of irradiance on nitrate uptake and dissolved organic nitrogen release by phytoplankton in the Ross Sea. Cont. Shelf Res. 18, 971-990. 

Armstrong, R. (1999). An optimization-based model of iron-light-ammoninm co-limitation of nitrate uptake and phytoplankton growth. Limnol. Oceanogr. 44, 1436—1446. 

Table 17.3 Percent nitrate uptake by large-sized phytoplankton in upwelling areas...

Montoya, J. P., and McCarthy, J. J. (1995). Nitrogen isotope fractionation during nitrate uptake by marine phytoplankton in continuous culture. J. Plankton R S. 17(3), 439—464. 

Falkowski, P. G. (1975). Nitrate uptake in marine phytoplankton—comparison of half-saturation constants from 7 species. Limnol. Oceanogr. 20, 412—417. 

Yajnik, K. S., and Sharada, M. K. (2003). Ammonium inhibition of nitrate uptake by phytoplankton A new relation based on similarity and hyperbolicity. Curr. Sci. 85, 1180—1189. 

Blasco, D., Macisaac, J. J., Packard, T. T., and Dugdale, R. C. (1984). Relationship between nitrate reductase and nitrate uptake in phytoplankton in the Peru upweUing region. Limnol. Oceanogr. 29, 275-286. 

Parker, R. A. (1993). Dynamic models for ammonium inhibition of nitrate uptake by phytoplankton. Ecol. Model. 66, 113-120. 

Kanda, J., Ziemann, D., Conquest, L., andBienfang, P. (1989). Light-dependency of nitrate uptake by phytoplankton over the spring bloom in Auke Bay, Alaska. Mar. Biol. 103, 563-569. 

Figure 5 The effect of different marine N cycle processes on nitrate <5 N and concentration, assuming an initial nitrate <5 N of 5%o. The trajectories are for reasonable estimates of the isotope effects, and they depend on the initial nitrate <5 N as well as the relative amplitude of the changes in nitrate concentration (30% for each process in this figure). A solid arrow denotes a process that adds or removes fixed N from the ocean, while a dashed line denotes a component of the internal cycling of oceanic fixed N. The effects of these two types of processes can be distinguished in many cases by their effect on the concentration ratio of nitrate to phosphate in seawater. The actual impact of the different processes on the N isotopes varies with environment. For instance, if phytoplankton completely consume the available nitrate in a given environment, the isotope effect of nitrate uptake plays no major role in the <5 N of the various N pools and fluxes the effect of nitrate generation by organic matter degradation and nitrification, not shown here, will depend on this dynamic. Similarly, the lack of a large isotope effect for sedimentary denitrification is due to the fact that nitrate consumption by this process can approach completion within sedimentary pore waters.

Our same research group used tracer to measure the rate of inorganic N-uptake by phytoplankton to evaluate the relative importance of nitrogen cycling mechanisms for phytoplankton productivity in aquatic ecosystems (17), We measured nitrate uptake rates of 54.2 it 14.6 ftg-N/h in an oligotrophic lake. The precision of these measurements as well as the wide range over which they have been effectively used demonstrate the advantages of short-lived radioisotopes for tracer biochemistry. 

Table 2.10. Half saturation constants (Kb) for nitrate uptake of phytoplankton...

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