Plankton nitrogen

Cabrita, M., Catarino, T., and Slawyk, G. (1999). Interactions of light, temperature and inorganic nitrogen in controlling planktonic nitrogen utilization in the Tagus estuary. Aquat. Ecol. 33, 251-261. 

Slawyk, G., Coste, B., CoUos, Y., and Rodier, M. (1997). Isotopic and enzymatic analyses of planktonic nitrogen utilization in the vicinity of Cape Sines (Portugal) during weak upweUing activity. Deep Sea Res. 44, 1—25. 

Ghbert, P. M. (1998). Interactions of top-down and bottom-up control in planktonic nitrogen cy chng. Hydrobiologia 363, 1—12. 

Kudela, R. M. (1995). Characterization and Prediction of Planktonic Nitrogenous Nutrition and New Production in Monterey Bay, Cahfornia Nutrient and Physiological Interactions. PhD Thesis. University of Southern California. 

Marino, M., Chan, F., Howarth, R. W., Pace, M., and Likens, G. E. (2002). Ecological and biogeochemical interactions constrain planktonic nitrogen fixation in estuaries. Ecosystems. 5, 719-725. 

Mugidde R. (2001) Nutrient status and planktonic nitrogen fixation in Lake Victoria, Africa. PhD Thesis, University of Waterloo. 

Figure 5. Average rate of planktonic nitrogen fixation plotted vs. average concentration of dissolved inorganic phosphorus (DIP) for a variety of freshwater and marine ecosvstems. Freshwater ecosystems—solid sysmbols marine ecosvstems—hollow symbols (Howarth et al. 1988).

I Dissolved Inorganic Nitrogen Detritus Nitrogen Planktonic Nitrogen... 

Other limitations on phytoplankton growth are chemical in nature. Nitrogen, in the form of nitrate, nitrite and ammonium ions, forms a basic building material of a plankton s cells. In some species silicon, as silicate, takes on this role. Phosphorus, in the form of phosphate, is in both cell walls and DNA. Iron, in the form of Fe(III) hydroxyl species, is an important trace element. Extensive areas of the mixed layer of the upper ocean have low nitrate and phosphate levels during... 

Fig. 10-13. The links between the cycling of C, N, and O2 are indicated. Total primary production is composed of two parts. The production driven by new nutrient input to the euphotic zone is called new production (Dugdale and Goering, 1967). New production is mainly in the form of the upward flux of nitrate from below but river and atmospheric input and nitrogen fixation (Karl et al, 1997) are other possible sources. Other forms of nitrogen such as nitrite, ammonia, and urea may also be important under certain situations. The "new" nitrate is used to produce plankton protoplasm and oxygen according to the RKR equation. Some of the plant material produced is respired in the euphotic zone due to the combined efforts...

Redfield (1934), who analyzed the major elemental content of many samples of mixed plankton (phytoplankton and zooplankton) caught in nets towed through the surface ocean. They compared the carbon, nitrogen, and phosphorus composition of these collections to concentration profiles of dissolved inorganic carbon (DIC), NOs, and P04 throughout the water column. This pioneering research demonstrated that these three elements are continually redistributed in the ocean by selective removal into plankton cells and their remains (i.e., fecal pellets), which are then efficiently respired as they sink through the marine water column. 

Marino R, Howarth RW, Chan F, Cole JJ, Likens GE (2003) Sulfate inhibition of molybdenum-dependent nitrogen fixation by planktonic cyanobacteria under seawater conditions a non-reversible effect. Hydrobiol 500 277-293... 

Not all chemical reactions proceed at rates fast enough to create significant deviations from NAECs. For example, although N2 gas is consumed by nitrogen-fixing plankton and produced by denitrifying bacteria, these processes are too slow to affect the relatively high seawater concentrations established by equilibration with the atmosphere. 

Equation 8.4 predicts that aerobic respiration should release dissolved inorganic nitrogen and phosphorus into seawater in the same ratio that is present in plankton, i.e., 16 1. As shown in Figure 8.3, a plot of nitrate versus phosphate for seawater taken from all depths through all the ocean basins has a slope close to 16 1. Why do both plankton and seawater have an N-to-P ratio of 16 1 Does the ratio in seawater determine the ratio in the plankton or vice versa Current thinking is that the N-to-P ratio of seawater reflects a quasi steady state that has been established and stabilized by the collective impacts of several biological processes controlled by marine plankton. 

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