RESULTS 



1. Unicellular organisms in bloom quantities were 

 found to reduce yellow light transmission in the sea. 



2. Light transmission was also reduced by other factors, 

 including organic material, particulate detritus, and dis- 

 solved pigments. 



3. The time and space distributions of microorganisms 

 and materials producing attenuation of light are complex, 

 but show relationships to thermal structure and water move- 

 ment caused by currents, tides, internal waves, and surface 

 agitation. 



4. The most important of the light-attenuating organisms 

 off Mission Beach, California, in the summer are the dino- 

 flagellates. The greatest concentration of dinoflagellates 

 usually occurs in the water in or above the thermocline. 



5. Macroplankton have little effect on light transmission. 



RECOMMENDATIONS 



1. Use the values of turbidity and the information per- 

 taining to the related abundance of organisms provided in 

 this report when optical or visual operations or installations 

 are required. 



2. Study the relation of phytoplankton blooms to physical 

 and chemical phenomena to produce criteria enabling predic- 

 tion of plankton bloom development and abateraent. 



