FISHERY BULLETIN: VOL. 70, NO. 4 



O 1.0 ly/min 

 A 0.53 ly/min 

 n 05 ly/min 



10 20 



TEMPERATURE »C 



30 



Figure 4. — Growth rate vs. temperature relationship 

 predicted by the Baly equation as used by Riley, Stom- 

 mel, and Bumpus (1949). Three different levels of total 

 radiant energy are included for the Baly equation: 1.0 

 (circles), 0.53 (triangles), and 0.05 ly/min (squares). 

 The line of maximum expectation predicted by Equation 

 (1) is drawn for comparison (no symbols). 



in the Sargasso Sea, the Eastern Tropical Pa- 

 cific, and southern California coastal waters. 

 Exceptions are jx estimates obtained from up- 

 welling regions off Peru (Strickland, Eppley, 

 and Rojas de Mendiola, 1969; Beers et al., 1971) 

 and southwest Africa (Hobson, 1971) where 

 nutrient limitation is not a factor reducing yu. 



A summary of estimated values of [x, as av- 

 erage doublings of cell carbon/day in the 

 euphotic zone, is provided in Table 2. The re- 

 cent data are based upon simulated in situ tech- 

 niques usually involving 24-hr incubation in 

 order to obtain photosynthetic rates free of er- 

 rors resulting from diel periodicity in metab- 

 olism. The list of values given is not inclusive 

 but is, hopefully, representative. Mean values 

 of fjL in the Peru Current showed little variation 

 and averaged about 0.7 doubling/day. Values 

 of this magnitude are consistent also with esti- 

 mates from ^^N-labeled nitrate assimilation rates 

 measured by R. C. Dugdale, J. J. Goering, and 



Table 2. — Some estimates of the average specific growth rate of phytoplankton in the 

 euphotic zone for various regions. Temperatures indicated are for the surface or the 

 average in the mixed layer. 



Location 



Temper- 

 ature 



Growtti rate as 

 doublings/day 



Reference 



' From Equation (1) assuming ^ will be one-half the value calculated as expected if daylength Is 12 hr and /t is 

 directly proportional to the number of hours of light per day. 



1070 



