Composition phytoplankton cells

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. 

Release rates of exudates from phytoplankton range from 0 to 80% of carbon fixed. These rates are dependent on species composition, physiological state, nutrient deficiency, temperature, and Ught limitation. Some evidence suggests that exudation is a mechanism for release of excess organic matter from cells when nutrient availability is too low to enable their usage as metabolic fuel. 

Even more complex is C-isotope fractionation in aquatic plants. Factors that control the of phytoplankton include temperature, availability of C02(aq), light intensity, nutrient availability, pH and physiological factors such as cell size and growth rate (Laws et al. 1995, 1997 Biigare et al. 1997 Popp et al. 1998 and others). In particular the relationship between C-isotope composition of phytoplankton and concentration of oceanic dissolved CO2 has been subject of considerable debate because of its potential as a palaeo-C02 barometer (see discussion). 

Phytoplankton at the ocean surface maintain the fluidity of their cell membranes by altering their lipid (fat) composition when the temperature changes. When the ocean temperature is high, plankton synthesize relatively more 37 2 than 37 3.35... 

The carbon isotopic composition of phytoplankton has been shown to be strongly affected by the />( (>2 of surface waters in the ocean (Rau et al., 1989, 1992). Moreover, fractionation of carbon isotopes by phytoplankton is also correlated with cell growth rate, cell size, cell membrane permeability, and CO2 (aq) (Laws et al., 1995 Rau et al., 1997). 

Smith EM (1998) Coherence of microbial respiration rate and cell-specific bacterial activity in a coastal planktonic community. Aquat Microb Ecol 16 27-35 Smith WO Jr, Nelson DM, DiTullio GR, Leventer AR (1996) Temporal and spatial patterns in the Ross Sea phytoplankton biomass, elemental composition, productivity and growth rates. J Geophys Res 101 18455-18466 Smith WO Jr, Marra J, Hiscock MR, Barber RT (2000) The seasonal cycle of phytoplankton biomass and primary productivity in the Ross sea, Antarctica. Deep-Sea Res II 47 3119-3140... 

Dutz J, Koski M (2006) Trophic significance of solitary cells of the prymnesiophyte Phaeocystis globosa depends on cell type. Limnol Oceanogr 51 1230-1238 Eilertsen HC, Schei B, Taasen JP (1981) Investigations on the plankton community of Balsfjorden, northern Norway the phytoplankton 1976-1978. Abundance, species composition and succession. Sarsia 66 129-141... 

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