Phytoplankton chemical composition

Arsenic geochemistry in Chesapeake Bay, Maryland, depends on anthropogenic inputs and phytoplankton species composition (Sanders 1985). Inputs of anthropogenic arsenic into Chesapeake Bay are estimated at 100 kg daily, or 39 tons/year — probably from sources such as unreported industrial discharges, use of arsenical herbicides, and from wood preservatives (Sanders 1985). The chemical form of the arsenic in solution varies seasonally and along the axis of the bay. Arsenic is present only as arsenate in winter, but substantial quantities of reduced and methylated forms are present in summer in different areas. The forms and distribution patterns of arsenic... 

Goldman, J. C., J. J. McCarthy, and D. G. Peavey. 1979. Growth rate influence on the chemical composition of phytoplankton in oceanic waters. Nature 279 210-215. 

In all cases where complete elemental analyses have been found, samples were isolated by SPE using XAD resins. As discussed earlier, this method isolates mainly hydrophobic organic compounds from seawater and is strongly biased against N-containing compounds. Polar ionic solutes have little or no affinity for XAD resins. There are perhaps more published results than have been found in this review, but the data in Table 11.4 are hopefully representative of elemental analyses for isolated samples of marine DOM. For reference, two calculated estimates of the bulk chemical composition of marine phytoplankton are included in Table 11.4. All elemental compositions in Table 11.4 are expressed as molar quantities in Redfield format, using an empirical formula that contains 106 moles of C. 

The two estimates of the chemical composition of marine phytoplankton provide a point of reference for the isolated samples of marine DOM. Significant trends can be better observed in this admittedly small data set by considering the plots of molar H/C versus O/C and H/C versus N/C in Figure 11.3. It is strikingly clear in Figure 11.3A that the samples isolated using NH4OH are distinctly enriched in H, and one... 

Mague, T. H., Mague, F. C., and Hokn-Hansen, O. (1977). Physiology and chemical composition of nitrogen-fixing phytoplankton in the central north Pacific ocean. Mar. Biol. 41, 212—227. 

Moal, J., Martin-Jezequel, V., Harris, R. P., Samain, J.-F., and Porflet, S. A. (1987). Interspecific and intraspecific variabflity of the chemical composition of marine phytoplankton. Oceanol. Acta 10(3), 339-346. 

Obviously the composition of natural waters is markedly influenced by the growth, distribution, and decay of phytoplankton and other organisms. The dominant role of organisms in regulating the oceanic composition and its variation with depth of some of the important sea salt components (i.e., C, N, P, and Si) will be illustrated here by introducing certain aspects of Broecker s kinetic model for the chemical composition of seawater (Broecker and Peng, 1982). We summarize Broecker s line of arguments. 

Keywords DOC, Excretion, Chemical composition. Lysis, Adriatic Sea, Physiological mechanisms, Phytoplankton. 

Other roles for noxious metabolites produced by certain phytoplankton species include mediation of allelopathic interactions [47]. Allelopathy covers biochemical interactions among different primary producers or between primary producers and microorganisms. These can provide an advantage for the producer in the competition among different photoautotrophs for resources. Although not directly involved in chemical defense, allelopathic metabolites can affect the dominance and succession of species in phytoplankton therefore they are crucial for understanding plankton composition. In contrast to the fresh water environment, the location of many studies on the role of allelopathic interactions, which have identified active compounds [47], only few studies have addressed this topic in the marine environment. 

An alternative approach for screening the composition of phytoplankton exudates is to use either 14C-tracer methods combined with chemical fractionation (Hama and Handa, 1987 Siuda and Wcisko, 1990 Sundh, 1991) or colorimetric methods (Obernosterer and Herndl, 1995 Biddanda and Benner, 1997) to characterize the contribution of different classes of organic compounds (carbohydrates and amino acids in polymeric or monomeric forms) to the total pool of exudates. These studies revealed that monomeric and combined carbohydrates were the major components of exudates, typically accounting for 20-90% of the total extracellularly released DOM. 

Hamm CE, Rousseau V (2003) Composition, assimilation and degradation of Phaeocystis globosa-derived fatty acids in the North Sea. J Sea Res 50 271-283 Hay ME, Kubanek J (2002) Community and ecosystem level consequences of chemical cues in the phytoplankton. J Chem Ecol 28 2001-2016 He J, Shi Z, Zhang Y, Liu Y, Jiang T, Yin Y, Qi Y (1999) Morphological characteristics and toxins of Phaeocystis cf pouchetii (Prymnesiophyceae). Oceanol Limnol Sin 30 76-83... 

---