45 



always the most common c On the other hand, when dinof lagellates 

 constitute the greatest numbers, several species may contribute. 

 The main contributors are Ceratium tripos and Ceratium fusus . 

 The greatest number of organisms within the zooplankton group 

 are normally nauplius larvae and copepods. All others are 

 generally low. However, in August and September 1955, radio- 

 larians were as numerous or more so than the other zooplankton. 



Although continuous sampling was not conducted in each 

 area, because of the similarity of oceanographic conditions 

 and the proximity of the outfalls to each other, it is likely 

 that no major differences existed in the dominant organisms 

 in the three areas, Allen found this to be the case in 

 localities as far apart as La Jolla and Oceanside. Therefore, 

 it is believed that differences which may have been noted in 

 the percentages at the different outfall areas during the year 

 were probably due to seasonal variations rather than differ- 

 ences due to locality. 



SUMMARY 



It is apparent both from the increase and volume of 

 plankton and the increase in nutrient salts in the proximity 

 of the boil that the presence of sewage has a great effect on 

 the reproductive rate of planktonic organisms. The question 

 arises, therefore, as to whether or not the increased nutrients 

 initiate a rapid reproductive growth of plankton or a plankton 

 bloom. It can be seen that there is by no means a steady state 

 of plankton numbers in the vicinity of sewage outfalls. There 

 is, however, a steady state condition of the nutrient concen- 



