Diatoms planktonic

Brzezinski, M. (1992). CeU-cycle effects on the kinetics of silicic acid uptake and resource competition among diatoms. /. Plankton Res. 14, 1511—1539. 

Guillard, R. R. L., and Ryther, J. H. (1962). Studies of marine planktonic diatoms 1. Cyclotella nana Hustedt and Detonula confervacea (cleve). Canadian J. Microbiol. 8 229-239. 

Pohnert G (2005) Diatom/copepod interactions in plankton the indirect chemical defense of unicellular algae. ChemBioChem 6 946-959... 

Falkowski PG, Katz ME, Knoll AH, Quigg A, Raven JA, Schofield O, Taylor FJR (2004) The evolution of modem eukaryotic phytoplankton. Science 305 354-360 Flynn KJ (2005) Castles built on sand dysfunctionality in plankton models and the inadequacy of dialogue between biologists and modellers. J Plankton Res 27 205-210 Fontana A (2007) Chemistry of oxylipin pathways in marine diatoms. Pure Appl Chem 79 481 490... 

Pohnert G (2004) Chemical defense strategies of marine organisms. In Schulz S (ed) Chemistry of pheromones and other semiochemicals, vol 1. Springer, Berlin, pp 179-219 Pohnert G (2005) Diatom/copepod interactions in plankton the indirect chemical defense of unicellular algae. ChemBioChem 6 946-959... 

Since all seawater is undersaturated with respect to BSi, plankton that deposit siliceous hard parts must fight unfevorable thermodynamics. In the case of the diatoms, the phytoplankton have specialized proteins that help concentrate the DSi intracellularly... 

In some cases, exudates enable the plankton to control their environment. For example, diatoms release compounds, called oxyUpins, that induce natural abortions and growth reduction in the zooplankton that are their primary predators. Other exudates complex with trace metals, serving to reduce the bioavailability of toxics, such as copper, and enhance the bioavailability of micronutrients, such as iron. Examples of iron-binding extracellular DOM are the siderophores (Figure 5.11). 

Labile and refractory DOM undergo abiotic photochemical reactions in the photic zone, especially in the sea surfece microlayer where physical processes concentrate DOM into thin films. Some of these reactions appear to be important in the formation of refractory DOM and others in its degradation. For example, DOM exuded by diatoms during plankton blooms has been observed to be transformed into humic substances within days of release into surfece seawater. Laboratory experiments conducted in seawater have demonstrated that photolysis of labile LMW DOM promotes the chemical reactions involved in humification and produces chemical structures foimd in marine humic substances. 

Fig.1 Generalized pelagic food web [ 13]. The old view of a simple food chain vertical line in this figure) with phytoplankton (mainly diatoms) at the base, herbivorous mesozoo-plankton (mainly copepods) at the second trophic level, and planktivorous fish has been extended to a pelagic food web including nanoplankton (<20 pm), picoplankton (<2 pm), and their protozoan feeders lower left). Herbivorous tunicates and jellyfish as primary carnivores also play a role, as do mixotrophic flagellates. The main pathway of energy flow depends on the nutrient scenarios [13]. DOC=dissolved organic carbon, HNF=heterotrophic nanoflageUates. From [13] with permission of Kluwer Academic Press...

Table 8.30 shows the chemistry of seawater compiled by Turekian (1969) for major, minor, and trace constituents, expressed in parts per billion (ppb) at a mean salinity of 35. The listed values are estimates of mean amounts in solution, whereas elemental concentrations actually vary with depth. The most conspicuous variations are observed in the first 200 m from the surface, where photosynthetic processes are dominant and phosphorus and nitrogen are fixed by plankton and benthos, as well as silica and calcium, which constitute, respectively, the skeletons of planktonic algae (diatom) and the shells of foraminifera and mollusks. 

In spite of his devotion to organic and inorganic chemistry, Cleve never lost interest in biology. During bis later years he made an extended study of the plankton of Skagerak and the North Sea, especially of the freshwater algae and diatoms, in order to locate the ocean currents. 

---