Figure 1, 2, and 3 show geometric means 

 and numbers of observations, for each of the 

 14 areas for which data were available, for 

 surface chlorophyll a, surface primary pro- 

 ductivity, and zooplankton (0 to 300 m. from 

 oblique hauls), in July to December (based on 

 data of table 2). In these and other figures, 

 means based on fewer than 10 observations 

 have been omitted. 



As has been explained, the data on chlo- 

 rophyll a consist of all observations for the 

 solar day and the zooplankton data consist of 

 all observations regardless of time. Within 

 these solar-day and full-day periods, time- 

 connected effects can cause the properties to 

 vary by a factor of about two (chlorophyll §) 

 or about three or four (zooplankton); I as- 

 sume that these differences approximately even 

 out. 



In figure 3, and in the corresponding figure 6 

 for zooplankton of January to June, the means 

 for area 3 are not based on the data of table 

 2, because collections at to 300 m. were so 

 few. Instead, means for zooplankton from to 

 140 m. were calculated for the halves of the 

 year from data in table 4 of Thrailkill (1963) 



and converted into estimates for to 300 m. 

 by the use of a regression (Blackburn, 

 1966). 



The area means for chlorophyll a (fig. 1) 

 show the expected trends: the highest values 

 (0.70 and 0,30 mg./m.3)were for the coastal 

 upwelling areas 12 and 13; next were areas 5 

 and 10 (0.19 and 0.18) in which the the rmocline 

 was closest to the sea surface; farther off- 

 shore, values declined gradually as the ther- 

 mocline sank deeper below the surface, to a 

 minimum of 0.05 in area 14; the value in area 

 3 was low (0.12) because little upwelling takes 

 place there in July to December; the slightly 

 higher value in area 9 (0.14) reflects up- 

 welling along the equatorial divergence. 



Area means for productivity (fig. 2), though 

 based on smaller numbers of observations, are 

 distributed in muchthe same way; some differ- 

 ences can be seen nevertheless. Area 12 was 

 again the most productive (25.8 mg.C/m.3/ day), 

 but it was followed by area 10 (20.5), area 

 9 (16.5), area5 (15. 7), and area 13(10.9). These 

 areas were the five best for chlorophyll a, 



SURFACE PRIMARY PRODUCTIVITY 

 JULY- DECEMBER 

 MG C/M'/DAT 



Figure 1. — Geometric means and (in parentheses) numbers 

 of observations of surface chlorophyll a^ in milligrams 

 per cubic meter, for each of the areas 1 to 14, in July to 

 December. Daylight data only; asterisk indicates < iO 

 observations; for further explanation see text. 



Figure 2.— Geometric means and (in parentheses) numbers 

 of observations of surface primary productivity in 

 milligrams of carbon per cubic meter per day, for each 

 of the areas 1 to 14, in July to December. Daylight data 

 only; asterisk indicates <10 observations; for further 

 explanation see text. 



