43 



tration. It appears, therefore, that in some years increased 

 populations may be expected in the winter months. It is 

 conceivable that the great quantities of nutrients contributed 

 by the sewer outfalls may result in this distinction between 

 what is the norm for seasonal distribution and the distribution 

 during the past year» If this were so, however, one would 

 expect to find a variation in the distribution of nutrients 

 during this period, or differences in the sewage constituents. 

 Such are not the case. 



The nutrients are more or less in a steady state condition 

 in their contribution to the coastal waters. In Biscayne Bay, 

 Florida, where sewage is discharged into the upper end of the 

 bay, such a condition leads to plankton volumes that are 

 uniformly higher in the upper portion of the bay than in the 

 lower (Smith, Williams, and Davis, 1950), However, due to the 

 many variations existing in the water and currents in the open 

 ocean, as noted above, steady state plankton growth could not 

 be expected except in such a confined environment. 



The variation in the different groups of plankton through 

 the past year is shown in Figure 16. The greatest per cent 

 of dinoflagellates occurs in the month of June. This is 

 followed by a continual but gradual decrease through May. 

 The diatoms are greatest in percentage in the cold months of 

 the year, decrease in June, and then follow a gradual rise to 

 their greatest numbers in January. Zooplankton reach their 

 peak in September, where they constitute a greater percentage 

 than either of the other two groups. When diatoms are the 

 most abundant plankton type, the diatoms Chaetoceros spp. are 



