Conclusions 



The Third Joint US-USSR Bering & Chukchi Seas 

 Expedition was very productive. It provided new information 

 and improved data sets to enable better understanding of the 

 processes that are occurring in these subpolar-polar regions. 

 Several measures of biological activity confirmed that the 

 summertime productivity here is extremely high, matching 

 some of the highest natural biological activity in the world. As 

 expected, the activity was also quite variable. This variability 

 was caused by several interacting factors. The most dominant 

 factor for this system is the upwelling of nutrient-rich deep 

 current waters that takes place predominantly on the northern 

 Bering Sea Shelf and within and the Chirikov basin. Some 

 representative high values of biological activity that were 

 measured are as follows: 800,000 cells/ml and 18 |ig C/1 for 

 bacteria for the northern Bering Sea; bacterial destruction rates 

 of 107 |ig C/l/d in the Bering Sea; 1,800 mg C/mVd of carbon 

 fixation in the Chirikov basin; phytoplankton counts between 

 500 and 1 ,700 cells/ml in the Chirikov basin; average biomass 

 of 40 g wet weight/m- for microzooplankton in the Chirikov 

 basin; and benthic biomass in excess of 400-500 g/m- in 

 productive areas. 



As with previous BERPAC expeditions, the intricate 

 balance of numerous processes working together was verified. 

 A modeling effort revealed the obvious importance of 

 seasonality to regulating this biological activity but it also 

 demonstrated the importance of taking a more holistic approach 

 to future studies. Plans for future modeling are being built 

 around carbon cycling. Carbon is also central to the problems 

 involved with global climate; therefore, it is important to 

 understand more fully the role of carbon processes that are 

 taking place in the Bering-Chukchi Seas ecosystem. Initial 

 data were accumulated on the carbon budget of this system. As 

 a likely carbon sink, this area has an important role in 

 minimizing CO, increase worldwide, especially since increasing 

 CO, may be the single most important factor leading to global 

 warming. The estimated flux of dissolved carbon to the 

 Chukchi Sea-Arctic Ocean amounted to 0.82 x 10" metric tons 

 per year. A significant portion of this carbon likely finds its 

 way to the deeper waters of the Arctic Ocean and eventually 

 may be incorporated into the North Atlantic bottom water. 

 Both of these avenues would act as a sink for greenhouse gas. 

 In addition to its significant impact on the carbon budget, the 

 Bering and Chukchi Seas area also plays a critical role in global 

 climate processes because of the major northward current flow 

 that arrives from the deep Pacific and that is part of the global 

 current that has a central role in regulating the world's climate. 

 This oceanic current is largely responsible for the high 

 productivity of the Bering-Chukchi region and thus, the fisheries 

 and economy of the area are intimately linked to this system. 

 Achieving a better understanding of this current flow and its 

 link to the biology of this system is therefore of extreme 

 importance. 



The expedition provided further evidence to show that 

 there is still much about the processes taking place in this 

 ecosystem that is only poorly known. For example, using 

 observations from the Gulf of Anadyr and along the Chukchi 

 Peninsula, it was possible to confirm the hypothesis about the 

 current entering the Gulf of Anadyr with a large quantity of 

 nutrients to produce production-deposition centers in the Gulf 

 of Anadyr and Chirikov basin. Also, improved access to areas 

 in the Chukchi allowed di.scovery of many new features about 

 this system. For example, evidence was found for a previously 

 unreported southerly flow of nutrient- and salt-rich water 

 flowing southward along the Siberian coast and merging with 

 the northerly flowing Bering Strait water. Also, many zonal 

 current patterns were identified in the Chukchi basin that had 

 major effects on the biology of the system — for instance, bird 

 sightings, optical measurements, and Cs'" concentration 

 profiles. 



Considering the fact that such an intense period of biological 

 activity is compressed into the relatively short ice-free period 

 in this region, there is a great deal of concern that disruptions, 

 even though relatively slight, may have profound effects on the 

 ecosystem components and functions. Anthropogenic 

 influences were one of the effects that were studied. Monitoring 

 at specific sites provided information for long-term assessments. 

 With benzo(a)pyrene (BaP) and polychlorinated biphenyls 

 (PCB's), the concentration levels have remained relatively 

 stable since the 1981 and 1984 BERPAC cruises; for DDT, the 

 levels have declined. The absolute abundance of 

 bacterioplankton has increased since the summers of 1 98 1 and 

 1 984, and for this expedition the indices for microbial cenoses 

 were five times higher than they were in 1984. Indirect 

 evidence of an anthropogenic impact is indicated by the fact 

 that species that can tolerate and metabolize certain pollutants 

 were isolated from these regions. These species also appeared 

 to have increased in abundance over the 1984 levels. In toxicity 

 tests with mixed populations of pelagic flora, harmful effects 

 were observed with BaP and copper at LD,^ values as low as 

 2 ppm. These concentrations are approached by the natural 

 levels measured in this region. Representatives of several 

 taxonomic groups of bacteria from the region were isolated that 

 had the potential to produce products with mutagenic or 

 genotoxic ( RN A damaging ) effects. Fortunately, for the present, 

 expression of this trait is unlikely, since factors leading to the 

 expression (i.e., extreme anthropogenic pressures or dense 

 bacterial abundance) do not presently exist in the Bering- 

 Chukchi Seas ecosystem, although the fact that the potential is 

 there is certainly cause for concern. 



Several organic contaminants were measured for the first 

 time in these areas. Among these were observations of high 

 levels of the hexachlorocyclohexane ( HCH ) class of compounds, 

 with an average concentration in water of 3.44 ng/1, and 

 toxaphenes. Also, chlordanes were measured in most samples 



405 



