St. Lawrence Island. The massive changes in the production 

 rates from south to north are most obvious in the three- 

 dimensional representation shown in Fig. 3. The highest value 

 (15 g C m-d') was found at Station 36 near St. Lawrence 

 Island. There were also secondary peaks at Station 55 in the 

 center of the Chukchi Sea (5.4 g C m -d '), Station 69 in the 

 Chirikov basin (4.4 g C m-d '), and Station 24 in the Gulf of 

 Anadyr (3.6 g C m-d'). A further breakdown of the data 

 (Table 1) shows the values at each station with means for 

 various regions. 



Daily Areal Primary Production 



36 



Fig. 3. Three-dimensional plot of primary productivity estimated during this 

 study. Horizontal contour intervals are 1000 mg C m- d '. The 

 numbers of selected stations are shown for orientation. Inset shows 

 , limits of the contoured region. 



Much of the primary production was subsurface, with 

 significant amounts below the themiocline in nutrient-rich 

 waters. The importance of subsurface production is shown in 

 Fig. 4. The peak in Fig. 4 is about 300 mg C m 'hr ' at a depth 

 of31 m. The high carbon assimilation rates are not necessarily 

 coincident with high chlorophyll ci values as shown in Fig. 5. 

 The major subsurface production peak at 63.5°N is in a region 

 where chlorophyll values were only about 1 mg m '. In another 

 area at 67°N there was a peak in chlorophyll that was not 

 associated with a production maximum. The productivity 

 peak, however, is associated with a nutricline as evidenced by 

 the NO, + NO, contours shown in the lower panel of Fig. 5. 



The P-I parameters were relatively uniform over the study 

 area as shown by the P„„, values in Figs. 6a and 6b. The values 

 were generally less than 1 mg C ( mg Chi ) ' hr ' , although some 

 exceptional values were higher. Surface P„„, values were also 

 generally higher than those from the deeper samples. 



Predictive modeling of primary production throughout the 

 season based on calculated solar irradiance (Brock, 1981), but 

 without taking account of ice cover, is shown in Fig. 7. 



Table 1 



Areal productivity in various regions on a daily and 



hourly basis. The means for each region are 



presented ± 1 standard deviation. 



Region 



Station 



mg C m- d ' 



mg C m - hr ' 



The notable points here are that the baseline of the graph slopes 

 downward from south to north, but the peaks of production 

 increased from south to north. This may be related to interactions 

 of limiting light and nutrients, or possibly the temperature 

 gradient. 



In relation to the international interest in global climate 

 change, the importance of the Bering Sea was also evaluated 

 by estimating the ZCO, at all primary productivity stations 

 (Table 2). Estimates of ZCO, flux through the Bering Straits 

 was calculated from the total transport of about 1x10'' m's' 



220 



