s 



1988 US-USSR CRUISE 



OOP BEWHO STATIONS 



(Tliousands) 

 DEPTH (m) 



Fig. 9. The vertical distribution of (A) nitrate and silicate (|J mole/1) and (B) 

 the nitrate/silicate ratio for all stations during the joint expedition. 



Discussion 



The biogenic nutiient content of the Bering Sea is closely 

 coupled to the primary production and regeneration process 

 occurring within its waters. The deep Bering Sea at South and 

 East Polygons have a continued supply of nitrate, silicate, and 

 phosphate to support primary production processes, but a 

 phytoplankton bloom with large chlorophyll concentrations 

 has not been observed. The high nutrients and low chlorophyll 

 are similar to the situation observed in the North Pacific Ocean 

 at Station P. The waters at depth in the deep Bering Sea hold 

 large quantities of nutrients compared to other parts of the 

 worid"s oceans, which indicates that the Bering Sea is a sink 

 rather than a source. This fact is also true for constituents other 

 than nutrients since there is no apparent ventilation of the deep 

 waters. Future work in the deep Bering Sea should focus on the 

 inputs to the deep water, its age and its level of anthropogenic 

 contamination. 



The Gulf of Anadyr receives deep waters from the open 

 Bering Sea and transmits these waters to Anadyr Strait, which 

 separates St. Lawrence Island from the Soviet mainland. The 

 waters in the Gulf of Anadyr are productive, especially near the 

 coastline where upwelling occurs. The resulting phytoplankton 



Fig. 10. The vertical distribution of (A) the dissolved inorganic nitrogen/ 

 phosphate ratio and ( B ) phosphate ((i mole/1) for all stations dunng the 

 joint expedition. 



probably act as a seed population for the upwelled water in 

 Anadyr Strait and provide organic matter to support regenerative 

 processes. Note that this nutrient regeneration occurs in the 

 deposition areas depicted by Coachman and Shigaev 

 ( Subchapter 2. 1 . this volume). The bottom water in the central 

 Gulf of Anadyr has the signature of winter water with its 

 extremely cold temperatures of <0.5°C. These waters slowly 

 transit through Anadyr Strait while being mixed with open 

 Bering Sea waters. 



The Chirikov basin acts as the "chemostat" in the ecosystem 

 by supplying large quantities of nutrients as inflows to ultimately 

 produce organic matter. The transit time through the Chirikov 

 basin may be so sinall that not all nutrients are utilized, similar 

 to a wash-out condition. The northward transport also includes 

 inner shelf water from the southeast Bering Sea that often 

 produces a separate phytoplankton bloom in the middle of 

 Chirikov basin (Hansell et al.. 1989). The majority of organic 

 matter and remaining nutrients advect northwiu'd along the 

 western edge into the Chukchi Sea (Hansell & Goering. 

 submitted). 



The Chukchi Sea receives the northward tlow of nutrients 

 and organic matter and further primary production occurs in the 

 central portion where surt'ace concentrations of nitrate are 



46 



