at 900°C for 1 .5 h, the tubes were cooled and opened on a high- 

 vacuum hne. The carbon dioxide and nitrogen gases were 

 cryogenically separated and the ratios of "C:'-C and "N;'^N 

 determined with a VG ISOG AS isotope ratio mass spectrometer. 



Fig. 1 . Station locations and distribution of euphausiid 6"C values from the 

 1988 Akademik Korolev cruise. Average 8"C values listed are from 

 Chukchi-Bering, western and eastern Beaufort Seas from 1985 to 

 1988. (from Saupefdi/., 1989). 



Results and Discussion 



The samples collected from \hc Akademik Korolev in 1 988 

 are listed in Table 1 . The data confirm the general patterns 

 found by Saupe el al. (1989) and show that a consistently 

 enriched 5"C fauna are present in the Bering Sea relative to the 

 Beaufort Sea. The data were separated into general taxonomic 

 groups and compared by region (Chukchi Sea versus Bering 

 Sea) and by subregions (eastern versus western Bering Sea, 

 etc.) using nonparametric statistics. The comparisons showed 

 that no significant regional differences exist in the isotope 

 ratios of the zooplankton from the Bering and Chukchi Seas. 

 Although the samples span both the Anadyr and Alaska Coastal 

 water masses, no significant difference was found between any 

 of these adjacent waters. However, there are significant 

 differences in the isotopic ratios when similar taxa are compared 

 from the Bering-Chukchi region and the eastern Beaufort 



region. Figures 1 and 2 show 5"C values for euphausiids and 

 copepods from the stations sampled on board the Akademik 

 Korolev. These data are compared with the previous findings 

 by Saupe «-? «/. (1989). 



The isotope data do reveal that the mean 5"C values of 

 both copepods and euphausiids were depleted by approximately 

 1 °/„, when compared to the Bering Sea data of Saupe et al. 

 ( 1 989 ). Also substantiating the findings of Saupe et al. ( 1 989), 

 the euphausiids were again enriched by l.l°/oo relative to 

 copepods from the same area. The lack of regional differences 

 in the Bering-Chukchi data would seem to indicate that the 

 observed depletions in the 1988 samples were areawide. It is 

 noteworthy that the 5"C values in the baleen plates of the 

 bowhead whales collected over the past few years show multi- 

 year trends that are similar between animals. This would 

 indicate that the shifts in 5"C are caused by an environmental 

 or floristic change at the priinary producer level and are not due 

 to shifts in biomass fraction in the zooplankton prey of the 

 whales or shifts in feeding preferences by the whales. We do 

 not yet know the cause of these changes. 



Fig. 2. Station locations and distribution of copepod 5"C values from the 

 1 988 Akademik Korolev cruise. Average 5"C values listed are from 

 Chukchi-Bering, western and eastern Beaufort Seas from 1985 to 

 1988 (from Saupe el al. 1989). 



179 



