to the grams of C m -d ' (Whitledge et ol.. 1988). Fisheries 

 scientists were aware long before that this was a region of rich 

 productivity (Hood & Kelly, 1974; Washburn &Weller, 1986). 



The present study adds new data to this knt)wledge base. 

 It also confirms the patterns seen in the 1984 cruise. First, the 

 regions of upwelling and associated high production were 

 again seen, thus verifying that this is a continuing phenomenon. 

 Second is the large expanse of the deep production maximum. 

 The tighter grid spacing of stations in the present data set 

 allowed a clearer picture about the extent of these phenomena 

 and showed that they were localized in the region of the 

 northern Bering Shelf and the Chukchi Sea. 



Figure 5 shows the productivity, chlorophyll, and 

 NO3 + NO, concentrations along a north-south transect. The 

 patterns show that the highest production occurred where there 

 was upwelling of nutrient rich water. This tongue of water 

 broke through to the surface between 64° and 65°N. 

 Furthermore, P^^^ was generally lower in deep water than in the 

 surt'ace waters at the same location. At Station 36 (63°25'N, 

 172°10'W), however, the P„^, values were nearly identical in 

 surface and deep waters. These values were also higher than at 

 most of the other stations (Fig. 6). The subsurface position of 

 the primary productivity peak indicated that the phytoplanktoh 

 were possibly nutrient-limited in the surface waters. At stations 

 where upwelling appeared most intense and nutrient 

 concentrations were greater, the productivity rates were high. 

 However high, these rates were still not as great as in areas 

 where the water column was stratified. The magnitude of 

 vertical currents in the upwelling regions transport the 

 phytoplankton from high light to low light and back. This 

 circulation takes place at time scales that do not allow 

 physiological adaptation. Cellular levels of chlorophyll and 

 photosynthetic enzymes cannot be adjusted as rapidly as changes 

 in light intensity. 



In the Chukchi Sea, the productivity maximum (between 

 67° and 68°N ) was generally in the surface waters. Chlorophyll 

 concentrations there were also high, with a maximum centered 

 around 15 meters in depth. The contribution to total water 

 column production was greater at the surface than at the 

 chlorophyll maximum. This was due to the shading of the 

 deeper populations. This was not so at Station 36. however, 

 where surface chlorophyll concentrations were below 

 2 mg Chi m '. 



Overall, the primary productivity of the Bering and Chukchi 

 Seas was controlled by hydrographic conditions. There were 

 high photosynthetic rates near the Aleutian Islands 

 ( 1 .9 g C m -d"'), but not neariy the magnitude of those found at 

 higher latitudes (15 at Station 36). On the continental shelf, 

 there appeared to be a decline in production (0.7 g m'd ') and 

 a lower nutrient regime in the surface waters. This is indicative 

 that the populations there were nutrient-limited. The nutrient 

 stress was alleviated further north on the continental shelf. 

 Nutrient enrichment on the continental shelf was due to 

 upwelling and served to stimulate production. In the region of 

 the Bering Strait, topographic conditions led to turbulence and 

 enhanced mixing of the water column (including the 

 phytoplankton). The instability reduced production to some 

 extent ( 1.4 g m -d '). In the Chirikov basin and the Chukchi 



Sea, the stability of the water column was greater while nutrient 

 concentrations remained high. This combined effect produced 

 high photosynthetic rates (1-1.6 g m"-d'), especially in the 

 central portion of the area (5.4 g m-d '). 



It was clear from the data that the source of nutrients was 

 the deep Bering Sea water. This water mass upwelled onto the 

 continental shelf (see Coachman & Shigaev, Subchapter 2.1, 

 this volume). The northward flow then provided a source of 

 new nutrients and a standing stock of phytoplankton to the 

 Chukchi Sea and Arctic Ocean. There also appeared to be a 

 northern source of nutrients for the production maximum in the 

 Chukchi Sea (.see Coachman & Shigaev. Subchapter 2.1. this 

 volume). The origin of these nutrients is uncertain, but they 

 may be from the region near Wrangel Island and flow off the 

 Siberian coast. Some of these nutrients may have come from 

 the Bering Sea and be recirculating around the basin from the 

 previous year. 



The distribution of production, interestingly, nearly matches 

 the northern distributions of historical whaling data (Nasu, 

 1974). The regions of high primary production also match 

 historical dataofhighbenthicbiomass(Alton, 1974). Recently, 

 the link between phytoplankton production and high benthic 

 metabolism was shown by Grebmeier et al. (1988, 1989) for 

 the Bering and Chukchi Seas. Although food webs in oceanic 

 systems are difficult to quantify, the case of the Bering and 

 Chukchi Seas seems fairly clear. A major pathway is for 

 phytoplankton to sink to the bottom where they serve as a 

 carbon source for a detrital food web. This food web ultimately 

 feeds pollock and large mammals such as walrus {Odobeims 

 rosmarus) and the gray whale (Eschiichtius gihhosus). 

 Grebmeier ef «/.( 1 989 ) have implicated interannual variability 

 of phytoplankton production as the causative agent for 

 interannual variation in oxygen consumption rates in Bering 

 Sea water. Another major pathway is more typical of pelagic 

 systems, and that is through zooplankton. The relative 

 importance of these two pathways was not studied, but it seems 

 that in the northern Bering and Chukchi Seas, a large proportion 

 must go through the benthic pathway. 



The importance of the Bering Sea phytoplankton does not 

 end with food webs alone. The biology and chemistry of the 

 Bering Sea might serve as major modulators of atmospheric 

 CO,. The present study shows that about 166 metric tons of C 

 are taken up by phytoplankton a year. Much of this is, of 

 course, remineralized (Grebmeier et al.. 1989), but a fair 

 fraction is buried in the sediments. 



A second mechanism of isolating carbon from the 

 atmosphere is also possible. There are two major sources for 

 the formation of bottom water in the oceans, the Antarctic, and 

 the Norwegian Sea. Prior studies have shown that there is a 

 transport of about 15 Sv into the Bering Sea from the North 

 Pacific (Favorite, 1974). Most of that flow returns to the North 

 Pacific. Still, about 1 Sv passes through the Bering Strait into 

 the Arctic Ocean (Favorite, 1974) where circulation could 

 bring it to the North Atlantic. Since much of the flow would be 

 in deeper layers and under the ice cap. little of the CO, would 

 be transferred back to the atmosphere. With the appropriate 

 temperature and salinity, this water could form North Atlantic 

 bottom water. An interesting thought here is that during the 



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