Total Organic Ccuhan ami Nitrogen in Surface Sediments 



Both the quantity and quahty of organic matter reaching 

 the benthos inlluences bcnthic standing stock and sediment 

 respiration (Grebmeier et al., 1988; Grebmeier & McRoy, 

 1989). Total organic carbon (TOG) in surface sediments was 

 highest in the Gulf of Anadyr and the western region of the 

 Chukchi Sea ( Fig. 9 ), indicating a higher proportion of silt and 

 clay in these sediments. The lowest TOG occurred in sediments 

 under the Alaska Goastal Water (Fig. 9). The region north of 

 St. Lawrence Island to Bering Strait has relatively low total 

 organic carbon accumulating in the sediments due to the 

 increased current speeds in this region. Fine sands characterize 

 this sediment domain (Grebmeier era/., 1989). In addition, the 

 general shape of the TOG isolines follow the bathy metrically- 

 steered currents (Fig. 1). This is consistent with previous 

 findings that indicate the influence of hydrodynamics on organic 

 carbon loading and sediment composition, which in turn 

 influences benthic population community structure and biomass 

 in this region (Grebmeier et ai, 1988, 1989). 



High quality organic carbon settles to the benthos in these 

 shallow waters, as evidenced by the low G/N values in sediments 

 under the highly productive Gulf of Anadyr and Bering Shelf- 

 Anadyr waters (Fig. 10). In contrast, highestC/N ratios (lowest 

 quality material) occur in sediments underlying the outer shelf 

 sediments in the Gulf of Anadyr and Alaska Goastal water in 

 both the northern Bering and Chukchi Seas (Fig. 10). A similar 

 pattern was observed between 1 984 and 1 986 to the east of the 



Fig. 8. Distribution of benthic communities based on data Irom 1984-1986 

 (from Grebmeier rt a/., 1989) and 1988. 



Fig. 9. Distribution of total organic carbon Ci) in surface sediments during 

 August 1988. 



Fig. 10. Distribution of C/N rations (wt./wt.) in surface sediments during 

 August 1988. 



249 



