In the Chukchi Sea, waters appeared less saline (24.04 to 

 33.66%) than the Bering Sea, and only 5% of the stations had 

 salinities greater than 33%. Salinities less than 29.70% were 

 included in the 29.70-31.35% for analysis (Fig. 3b). 



In the Bering Sea, the highest mean number of SB 

 (3.7 X 10' cells/ml) occurred in warm waters, with temperatures 

 +6°C and salinity between 33.00 and 34.65%, which represented 

 a small percentage (3%) of the total number of analyzed 

 samples. These samples dominated the surface 25 m in the 

 southern Bering Sea (South Polygon and Station 1 13). 



Water samples from the Bering Sea with temperatures 

 higher than 6°C and salinity 3 1 .3 1-33.00% represented 25% of 

 samples. These samples were usually taken from the surface 

 25 m in the central, northwestern, and northern areas of the sea 

 and contained about 8.0 x 1 0- SB cells/ml ( Fig. 3 ). Mean values 

 of SB number with other pair combinations of temperature and 

 salinity grouped close to each other, 1.0 to 3.7 x 10' cells/ml 

 (Fig. 4). 



In the Chukchi Sea, the highest mean number of SB 

 (1.15 x 10^ cells/ml) also grouped in relatively warm waters 

 (> + 6°C), but in contrast to the Bering Sea, less saline waters 

 (>31.35%). The lowestmeannumberofSB(5.7x 10- cells/ml) 

 was similar to other pair combinations of temperature and 

 salinity, 4.7 to 6.0 x 10' cells/ml (Fig. 3). 



Ecogram analysis showed that during the cruise in the 

 Chukchi Sea, the saprophytic microflora grew rapidly as 

 maximal mean SB in the Chukchi Sea (1.15 x 10^ cells/ml) 

 occurred in warm, low salinity waters, typical of southeastern 

 water (Stations 65 and 66). An area affected by river flow from 

 the Alaska coast (Fig. 2). 



Hexadecane-oxidizing Bacteria in the Bering and Chukchi 

 Seas 



The most probable number of HDB in the central Bering 

 Sea, East Polygon, in summer 1988, varied between and 

 1.8 X 10' cells/ml. Maximum numbers occurred only at Station 

 3', at depths of 45 and 150 m. At other stations, HDB varied 

 less— 0-30, 0-180, and 0-300 cells/ml. 



In the South Polygon, HDB ranged between and 

 180 cells/ml at Station 1 12 (average 90 cells/ml). At the other 

 stations, HDB ranged from 0-1.8 x 10' cells/ml (averaged 

 between 180 and 700 cells/ml). Samples with maximum HDB 

 represented >10% of the total number of samples in this deep- 

 sea area (Fig. 4). 



This bacterial group varied vertically. The greatest vertical 

 variation occurred at a station nearest the St. Lawrence Island, 

 where HDB increased with depth, with practically no 

 hexadecane-oxidizing microflora in the near surface microlayer. 



Mean numbers of HDB in the section ranged between 10 

 and 100 cells/ml. Only at two stations. 7 and 19, did DB 

 numbers exceed 10- cells/ml. Generally, in the southeastern 

 Bering Sea, including the Gulf of Anadyr, HDB varied between 

 and 1.8 x 10' cells/ml. Hexadecane-oxidizing microflora 

 occurred in 72% of the samples. 



Fig. 4. Occurrence rale ['~i ) of various value.s of the mosl probable number 

 (MPN, cells/ml ) of heterolrophic saprophytic and other functions of 

 groups in the Bering and Chukchi Seas in summer 1988: 



(a) southern Chukchi Sea; 



(b) northern Bering Sea (Chinkov basin) and the Bering Strait; 



(c) the Gulf of Anadyr; and 



(d) central and southern Bering Sea. 



In the Chirikov Basin, HDB also varied between and 

 1.8 X 10' cells/ml, averaging between 10 and 100 cells/ml. 

 HDB increased at Station 83 in the Bering Strait and at Station 

 89 (Fig. 5). In general, the HDB distribution in the Chirikov 

 basin resembled the distribution in the open sea (Fig. 4). 



In the Chukchi Sea, HDB varied between and 

 1.8 X 10"* cells/ml. Their distribution appeared extremely 

 variable. Thus, at Station 66, only a few cells/ml occurred, 

 while at Station 49, they ranged up to 3.4 x 10' cells/ml 

 (Fig. 2). Generally, HDB occurred in 62% of the samples, but 

 at only 1 cells/ml ; waters that are characteristic of nonpolluted 

 seas (Fig. 4). A relatively high number ( 10- cells/ml) of HDB 

 occurred in 2 1 % of the samples. This may be explained by the 

 fact that microorganisms of this group also use aliphatic 

 hydrocarbon as a source of carbon and energy. The source may 

 be anthropogenic, but aliphatics also seep into the sea from 

 underwater oil fields, and are synthesized and subsequently 

 released by some seaweed. 



Prismatic ecogram analysis (Figs. 6,7) showed that the 

 largest mean numbers of HDB (7.1 x 10- cells/ml)in the Bering 

 Sea occurred in waters with high concentration of SB; that is, 

 waters with relatively high temperatures (>6°C) and salinities 

 (>33%) (Fig. 6). Such combinations of temperature and 

 salinity occurred in only 3% of the total number of analyzed 

 samples (Fig. 6). However, the numbers of hexadecane- 



84 



