Phytoplankton population variations

Diatoms make up only a portion of the total phytoplankton population variations in diatoms need not reflect general productivity. 

Hama J, Handa N (1992) Diel variation of water-extract-able carbohydrate composition of natural phytoplankton populations in Kinu-ura Bay. J Exp Mar Biol Ecol 162 159-176... 

Steele (1956) (6) found that the steady-state assumption did not apply to the seasonal variation of the phytoplankton population. Instead, he used two volume segments to represent the upper and lower water levels and kept the time derivatives in the equations. Thus, both temporal and spatial variations were considered. In addition, the differential equations for phytoplankton and zooplankton concentration were coupled so that the interactions of the populations could be studied, as well as the nutrient-phytoplankton dependence. The coefficients of the equations were not functions of time, however, so that the effects of time-varying solar radiation intensity and temperature were not included. The equations were numerically integrated and the results compared with the observed distribution. Steele applied similar equations to the vertical distribution of chlorophyll in the Gulf of Mexico (7). 

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