Phytoplankton coccolithophorids

Nanoplankton 2.0 to 20 jjum Protists Mycoplankton Phytoplankton Amoebae, flagellates, Euglenozoa, dinoflagellates Yeasts and fungi Coccolithophorids, Phaeocystis, dinoflagellates ... 

Second in importance to the sedimentary PIC flux are the detrital remains of coccol-ithophorids, a genus of phytoplankton. As shown in Figure 15.1b, these plants deposit calcium carbonate in plates (about 50 per cell) that overlap to create an external shell. An individual coccolithophorid will create and shed these plates on a continual basis at rate of about 1 per hour. The plates also separate from each other after death of the plant, especially if the detrital remains fell into waters that promote dissolution. These plates are referred to as coccoliths and have the crystalline structure of the mineral calotte. 

Coccolithophorids Phytoplankton that deposit calcareous plates called coccoliths. 

Coccoliths Calcareous plates deposited by phytoplankton called coccolithophorids. 

Iglesias-Rodriguez D. M., Brown C. W., Doney S. C., Kleypas J. A., Kolber D., Kolber Z., Hayes P. K., and Ealkowski G. P. (2002) Representing key phytoplankton functional groups in ocean carbon cycle models coccolithophorids. Global Biogeochem. Cycles 16 (in press). 

A diverse assemblage of phytoplankton and macroalgae, including diatoms, coccolithophorids (Palenik and Morel, 1988), charophytes (Ivankina and Novak, 1988), and cyanobacteria (Peschek et al., 1988) reduce extracellular electron acceptors. For example, the coastal diatom, Thalassiosira weissflogii, reduces Cu(II) and Fe(III) complexes via three independent reductants as shown in Fig. 3 (Jones et al., 1987) (1) Reductants released by the cells and free in solution that are quickly consumed and are not regenerated in the absence of cells, (2) cell surface moieties that are also rapidly exhausted and can be inactivated by pretreatment with oxidants, and (3) a cell surface reductase whose activity is light-independent. 

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