Nutrients and primary production

Ertehjerg Nielsen, G., Gargas, E., 1984. Oxygen, nutrients and primary production in the open Danish waters. Linmologica, 15, 303-310. 

Nitrogen pollution has received far more attention than that of phosphorus for two reasons. First, it has been considered as the nutrient-limiting primary production in estuaries and coastal waters. Second, its loading into the coastal zone has been far greater than that of phosphorus (Figure 24.21). It is also more efficiently exported into the ocean due in part to formation of iron phosphate minerals in anoxic estuarine sediments. 

To be useful to both, clinicians and the pharmaceutical industry, a bioartificial liver will need to maintain a large number of hepatocytes at high cell densities and in a fully differentiated state for prolonged periods of time. Development of such a system has been impeded by three principal problems a) a requirement for large numbers of cells (>25 10 ) b) loss of liver-specific functions in cultured cells (primary and immortalized) c) nutrient and waste product gradients in high density cultures leading to lowered cell viability and impaired function. 

Primary production in the ocean is controlled by major nutrients, such as nitrate and phosphate, but also by certain trace metals. Dissolved iron was hypothesized (over 50 years ago) to be a key nutrient limiting primary production rates in the sea. However, credible data for the concentration of dissolved iron in seawater have only become available in the last 8 years. Iron is present in surface seawater at concentrations less than 0.5 nanomole per kilogram. These low concentrations of dissolved iron suggest that it is, in fact, a nutrient that can limit primary production in the ocean (Martin et al., 1989). The role of iron in limiting productivity of the ocean can be resolved only when measurements of dissolved iron at concentrations below 1 nanomole per kilogram become routine. There is evidence that other trace metals could also control phytoplankton growth. 

Nixon, S.W. (1982) Nutrient dynamics, primary production, and fisheries yields of lagoons. Oceanologic Acta Special edition Proceedings, International Symposium on Coastal Lagoons, pp. 357-371, University of Rhode Island, Narragansett, RI. 

In this chapter we discuss the distribution and the development of plant communities in floodplain areas, mainly of the big whitewater rivers, focusing on factors such as diversity, species composition, biomass and primary production. Based upon these factors, we also discuss the annual dynamics of bioelements stocks and their turnover through herbaceous and floodplain forest communities. Finally, we examine the implications of such nutrient dynamics and turnover for the aquatic biota. We do not address carbon and nutrient budgets, as these are thoroughly discussed in chapter 14. 

In the Central North Pacific Ocean (CNPO) it has also been reported that phosphorus availabiHty limits N2 fixation and primary production (Karl et al, 2001 a,b) (but iron availability may also play a role as suggested by Wu et al (2000). Karl et al (2001a,b) contend that since the mid 1970s there has been an enhanced stratification in the CNPO and a decreased inorganic nutrient avadabihty which selects for diazotrophs and shifts from a N-hmited phytoplankton population to one that is either P or Fe Hmited (see Karl et al. Chapter 16, this volume). 

Carpenter, E. J., and Dunham, S. (1985). Nitrogenous nutrient uptake, primary production, and species composition of phytoplankton in the Carmans River estuary. Long Island, New York. Limnol. Oceanogr. 30, 513—526. 

Filippino, K. C., Bernhardt, P. W., and MulhoUand, M. R. Nutrient dynamics and primary productivity in the Chesapeake Bay outflow plume during 2005 and 2006. Estuaries and Coasts (submitted). 

Dugdale, R. C., and Wilkerson, P. P. (1988). Nutrient sources and primary production in the eastern Mediterranean. Oceanol. Acta Spec. 179-184. 

At low latitudes there is a permanent thermocline, but because a seasonal thermocline does not develop the surface and nutrient-rich deeper waters remain unmixed. Consequently, the euphotic zone, which lies above the permanent thermocline, becomes depleted in nutrients. Continued primary production is dependent upon the release of nutrients from detritus in surface waters. Productivity is, therefore, relatively low in tropical oceans but it is fairly constant, due to a year-round warm climate and ample sunlight (Fig. 3.7a). 

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