NOAA PROFESSIONAL PAPER 11 



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OmJuly 1976 



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Om August 1976 



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 1 - 



20m July 1976 



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20 m August 1976 



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MEAN SPHERICAL DIAMETER {\im) 



FIGURE 9.1-4 — Particle size frequency distributions from a station 8 km south of Fire Island Inlet, May to August 1976. (Data by Michael 



Dagg.) 



Once the water column stratified, the problem became 

 more complex as euphotic zone nutrients were depleted 

 and the C. tripos population aggregated near the base of 

 the thermociine. Although maximum cell densities were 

 observed in June, it is possible that population size did 

 not increase. The population was large enough by the end 

 of March to account for observed cell densities in the 

 maximum layer during June, Changes in cell density could 



have resulted from concentration of the existing popula- 

 tion as well as from the balance between growth and mor- 

 tality, 



C. tripos photosynthesizes in the presence of sufficient 

 light. In late April, C. tripos growth rates were 0,06 dou- 

 blings/d averaged over the euphotic zone and 0,02 dou- 

 blings/d at the 1 percent light depth. Local turbulence 

 disrupted the C. tripos layer off Long Island in May (fig. 



200 



