ILLUSTRATIONS 



1 Point Loma and Mission Bay, showing location of tower and 

 general current flows. . .page 6 



2 USNEL Oceanographic Research Tower located a mile off 

 Mission Beach. . . 7 



3 Top view of car, on vertical railway tracks of the tower, 

 used to make vertical casts for water turbidity and tempera- 

 ture and to pump water for plankton. . . 8 



4 Z-7recorder for water transparency (light transmission) vs. 

 depth for vertical casts with the hydrophotometer. . . 9 



5 Temperature and depth indicators for the car containing the 

 hydrophotometer. . . H 



6-12 Time -depth plots of water transparency at the USNEL tower. , . 13-16 



13-14 Comparisons of vertical temperature and transparency 

 gradients. . . i 7, 18 



15 Observations from the USNEL tower of an internal wave, 

 its associated slick, and red water. . .19 



16 The NK-7 echogram compared to the depth of an isotherm 

 in the thermocline. . .21 



17 Appearance of an echogram during the day and following 

 evening. . .82 



18 Sanaple of coarse red water showing Gonyaulax po lyedra . . . 23 



