PURPOSE 



This work attempts to determine the cause of turbid- 

 ity in a specific location through depth and time with partic- 

 ular emphasis on the role played by living organisms. 

 Consequently, the major portions deal with assessing the 

 concentrations of macroplanktonic and microplanktonic forms 

 and relating them to light transmission and thermal gradients, 

 Inanimate debris above 10 microns is also enumerated. 



"Microorganisms" and "microplankton" are defined 

 in this report as unicellular organisms greater than 10 

 microns and too small in their least dimension to be quanti- 

 tatively retained by 20-gauge nylon gauze with aperture 

 size of 76 microns. "Macroplankton" refers to organisms 

 retained by 20-gauge nylon gauze to a maximum of 2 mm. 



Most of the field work was carried out through two 

 day-night periods during July 1961, and supplementary data 

 were taken in July 1964. The 1961 periods are identified as 

 Operations I and II, E>uring Operation I, 1730 6 July through 

 1300 7 July, a condition known as "yellow water, " caused by 

 a bloom of a small naked dinoflagellate, Gymnodinium flavum 

 (Lackey and Clendenning, 1963), ^ provided an excellent 

 opportunity to assess the effect of motile, pigmented cells 

 on light transmission. By Operation II, 0900 20 July through 

 1200 21 July, the dinoflagellate bloom had abated and a more 

 complex and perhaps more typical situation was present. A 

 third operation was carried out 23, 24 July 1964 during a 

 "red water" bloom caused by the dinoflagellate Gonyaulax 

 polyedra. 



