Diatoms aquatic systems

Microphytobenthos microscopic plants (e.g., benthic diatoms) that grow on solid Surfaces in aquatic systems. 

Figure 38.2 A progressive shift from a Synechococcus-dominated community to a diatom-dominated assemblage with increasing Fe supply in an experiment in the Peru Upwelling region. A shipboard continuous culture system was used to supply a continuous flow of Fe-amended seawater at adilution rate of 1 day simulating upwelling of water with three different Fe concentrations. Iron supply rates used were 0.8,1.3, or 3.7 nmol Fe L day . Values are the means and error bars are the standard deviations of triplicate incubation bottles. Redrawn from Hare et al. (2005), Aquatic Microbial Ecology 38 269—282.

Most of the discrimination between inorganic and methylmercury thus occurs during trophic transfer, while the major enrichment factor is between water and the phytoplankton. This also has been reported for the diatom Thalassiosura weissflogii in a marine food chain (Mason et al. 1996). Methylmercury was accumulated in the cell cytoplasm, and its assimilation by copepods was 4 times more efficient than the assimilation of inorganic mercury. Bioaccumulation has been demonstrated for predator fish in both freshwater and marine systems and in marine mammals (see Section 5.4.4). Bioaccumulation of methylmercury in aquatic food chains is of interest, because it is generally the most important source of nonoccupational human exposure to this compound (EPA 1984b WHO 1990, 1991). 

Haworth, E.Y. (1985) The highly nervous system of the English Lakes aquatic ecosystem sensitivity to external changes, as demonstrated by diatoms. Rep. Freshwater biol. Ass. 53,60-79. 

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