Plankton Distribution 



The water at the tower contains 

 numerous species of both phyto- and 

 zooplankton, but frequently one organism 

 dominates. During one investigation 

 plankton populations and movements were 

 studied. Over 200 samples were collec- 

 ted at 3-meter intervals throughout the 

 water column. These repeated samplings 

 were made at 2-hour intervals for more 

 than 24 hours. 



At this time the main organism in 

 the bloom was a naked dinoflagellate, 

 Gymnodinium flavum (yellow water ) . It 

 was present in concentrations up to 3. 2 

 x 10 6 cells per liter. The bloom corre- 

 lated closely in space, time, and inten- 

 sity with a highly turbid layer (30- to 50- 

 percent transparency) , which was resting 

 on a strong thermocline. Pigmented- 

 cell zooplankton and organic detritus, 

 present in significantly lesser volume, 

 showed little correlation with the turbid 

 area. Two weeks later the turbid zone 

 was ill-defined. Gymnodinium had abated 

 to maximum concentrations of 4.8 x 10 ° 

 cells per liter, while another dinoflagellate, 

 Ceratimn, was associated with patchy 

 turbid areas. However, the most domi- 

 nant organism in recent years has been 

 Gonyaulax polyedra . Thus, the principal 

 organisms causing turbidity differ with 

 time and changing environmental conditions. 



A submersible pump collects planktonic material that 

 causes water turbidity in the tower area. The pump 

 brings fresh sea water by hose from a predetermined 

 (or continuously changing) depth up to a catwalk, 

 where a known volume is filtered with a plankton net. 



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