| As an important parameter to be considered in biochemical processes of marine phytoplankton, cell size plays a decisive role in the physiological processes of phytoplankton. Since that, a detailed description was given in this review about the influences of cell size on growth rate, photosynthesis rate, respiration rate and metabolism processes of phytoplankton, while the influences of environmental factors on cell size are also discussed. This review is in the purpose of laying solid foundation for further research on the dynamical mechanisms of phytoplankton cell growth processes.The sizes of twelve small (2-40um) phytoplankton species were investigated with an ocular micrometer in a microscope and a Coulter Counter. Gauss distribution function was utilized to describe the distribution of the mean percentage of the equivalent spherical diameter (BSD) of marine phytoplankton. According to the study results, it was found that the size distribution of marine phytoplankton could be described very well by Gauss function. The average relative parameters of plotting were 0.952 for micrometer and 0.985 for Coulter counter, respectively. Each kind of micro-phytoplankton had its characteristic distribution curve and mean BSD. From the fitting graphs, it can be seen that the distribution curves of phytoplankton have one peak for chlorophytes and chain form diatoms, however the distribution curves of harmful bloom algae seem to be more complicated. This may be induced by the specific mechanism of the growth of harmful bloom algae.The maximal growth rates (ax) of 8 species of marine phytoplankton are studied in detail. The size distribution of phytoplankton is investigated by daily analysis and the variation of equivalent spherical diameter (BSD) is observed. The size distribution of phytoplankton is well represented by a Gaussian distributionfunction. The value of the exponent b for most algae in the equation Umax= a BSD b (where max is the maximum specific growth rate, BSD is the median equivalent spherical diameter, and a and b are constants equal to 2.10><105 and -1.15, respectively) is obtained by nonlinear regression analysis with the Allometric function. A new model is used to describe the size-dependent growth rate and maximum cell density. The size of algal cells varied throughout the process of population growth, and the size distribution characteristic of phytoplankton did not change during the growth process.Accompanied with nutrients variation, the distribution type of cell size kept unchanged during the growth process of phytoplankton, which could be described by one Gauss function or a compound Gauss function. BSD changed in step with plankton growth. The increase of phosphate concentration had decreased the BSD for Gymnodinium sp. or Nitzschia closteriwn. But the increase of nitrate concentration reduced the BSD value at first, and then rose when the nitrate concentration reached a certain value. The relationship between umlx and BSD fitted the Allometric model well, with satisfactory non-linear fitting coefficient as 0.91, 0.85, respectively, which approved that negative exponential relation does exist between growth rate and BSD for single species of plankton, with narrower cell size distribution. In addition, the negative relation between instant ?and BSD indicated that package effects existed between ?and BSD for two species of plankton under unpolluted conditions.Under different carbohydrate concentration, the relationship between maximum growth rate, light adsorption capacity of Nitzschia closterium^ Gymnodinium sp. and Chaetoceros curvisetus and BSD was carefully studied. The results showed that the growth rate of phytoplankton was generally suppressed under comparatively high carbohydrate concentration, while lower concentration would promote the growth of Gymnodinium sp. and Chaetoceros curvisetus, but not for Chaetoceros curvisetus. The fitting analyses had demonstrated that the growth dynamic curve of these three species of marine phytoplankton fit the Logistic model well, with satisfactor... |
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