The consistent and precise relationship between 

 the distribution of Gymnodinium flavum and light transmission 

 implicated it as a primary cause of turbidity. This observa- 

 tion was corroborated by correlations cited previously be- 

 tween the distribution of G. flavum, total microorganisms, and 

 total microconstituents. The concentration of G. f/auum reached 

 3.9 X 10^ cells per ml and represented 6 5 percent of the 

 total particulate material counted in this study. 



While the degree of opacity and the true distribution 

 of these cells are unknown, calculations relating the com- 

 bined surface area of G. flavum at this high concentration to 

 the cross -sectional area of the light path (refer to MATHE- 

 MATICAL TREATMENT) indicated that cells in the quantity 

 sampled are sufficient to account for the measured turbidity. 

 Furthermore, examination of least-squares lines (figs. 8A 

 and C) and the theoretical curves (figs. 9A and C) reveals 

 positive correlations between concentrations of G. flavum and 

 total microconstituents compared to light transmission, 

 particularly when particle counts exceed 10 per ml. 



The correlation between the distribution of micro- 

 organisms and the thermocline is suggestive of two possibi- 

 lities — the colder water of the thermocline served as a 

 density barrier on which microorganisms settled and the 

 increased density concentrated organic debris necessary to 

 the microorganisms. Sorokin (1960)^''' cites the possibility 

 of more intensive multiplication of cells in the nutrient- 

 rich layer of the thermocline. He further cites thermal 

 density stratification as one of the main factors determin- 

 ing the vertical distribution of phyto plankton. Using under- 

 water television and scuba at the tower site, the authors 

 have frequently observed the increased turbidity associated 

 with the thermocline. 



Diatoms, fecal pellets, wood fibers, and miscellan- 

 eous debris (refer to appendix) showed no discernible rela- 

 tionship to turbidity except as these populations may have 

 contributed to bottom concentrations shown in total micro- 

 constituents. 



58 



