RED WATER 



While the occurrence of yellow-water blooms, 

 noted in Operations I and II, is a rare event (Kofoid and 

 Swezy, 1921, ' Lackey and Clendenning, 1963 ^), recent years 

 have seen a dramatic increase in the incidence of red-water 

 outbreaks. The causal organism of this phenomenon in 

 these waters is usually the small armored dinoflagellate 

 Gonyaulax polyedra. Since 19 59, during July and August, red 

 water has been generally present in varying degrees off 

 San Diego. Less frequent outbreaks occur during the fall 

 and late spring months. Reduced water transparency at 

 or near the surface off the southern California coast 

 during warm weather months is primarily due to this 

 phenomenon. Observations on red-water blooms from the 

 NEL tower were conducted during the summer of 1964, 

 and selected data pertinent to the prior work are included 

 herein. 



Transparency data acquired with the hydrophotometer 

 were taken before, during, and after the passage of red-water 

 patches through the tower site. Temperature was measured 

 with a bathythermograph. 



Figure 31 depicts light transmission and temperature 

 during the passage of red water on 23 July 1964. On this 

 date, the red water was first sighted seaward of the tower 

 at 1010. By 1034, when the first hydrophotometer run was 

 made, the red water was around the tower. A second and 

 heavier concentration was observed approaching the tower 

 at 1325. Light transmission on the descent of the hydro- 

 photometer (fig. 32) at this time was 61 percent at the 

 surface. Ascent, less than 10 minutes later through the 

 center of this patch, showed surface transparency had 

 been reduced to 38 percent, the difference undoubtedly 

 attributable to the increase of G. polyedra. The passage of 

 this red-water patch was bracketed by a hydrophotometer 

 run at 1325 (fig. 31) and another at 1505, when the water 

 began to clear. Transparency at the surface ranged from 

 31 to 89 percent between the hours of 1035 and 2100, when 

 the last values were recorded. Variations in transparency 

 from surface to near bottom through the same time period 

 ranged from 31 to more than 9 percent. 



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