levels were highest at stations occupied in the Chirikov basin 

 and the south-central Bering Sea (Figs. 5,8,9). A tabular listing 

 of stations, positions, and algal pigment concentrations is given 

 in the Table 1. 



Discussion 



The concentrations of photosynthetic pigments in the 

 marine environment are primarily dependent on the quantity, 

 species composition, and photoadaptative state of the 

 phytoplankton present. For these reasons, accessory chlorophyll 

 and carotenoid pigments have been used as diagnostic "tags" 

 for investigating algal distributions and their physiological 

 processes. In coastal waters off Australia, Jeffrey (1974) 

 documented the usefulness of acces.sory pigments for examining 

 phytoplankton distributions in the water column. The thin- 

 layer chromatographic method employed identified the major 

 pigments as chlorophylls a. h, and c: carotene; astaxanthin; 

 fucoxanthin; peridinin; diadinoxanthin; and neoxanthin. 

 Chromatographic data were used to "fingerprint" vertical and 

 temporal variations in the phytoplankton community structure. 



Several recent investigations have demonstrated the utility 

 of HPLC as a "chemotaxonomical" tool for identifying marine 

 algal groups. For example, high concentrations of zeaxanthin 

 were used to infer the presence of cyanobacteria in the North 

 Sea and tropical Atlantic Ocean (Gieskes& Kraay, 1983a). In 

 another study, the dominance of a symbiotic cryptomonad was 

 established for a spring bloom in the central North Sea by 

 HPLC identification ofalloxanthin, a carotenoid characteristic 

 of this marine algal group (Gieskes & Kraay, 1983b). HPLC 

 pigment analysis has also been shown to be useful for 

 characterizing phytoplankton biomass and compositional 

 changes across frontal systems located at the northern wall of 



the Gulf Stream (Amone et ai, 1986; Trees el al, 1986) and 

 in the Santa Barbara Channel (Smith et al, 1987). 



In this study, the criteria presented in Table 3 were used to 

 infer distributions for the major algal groups (diatoms, green 

 algae, dinoflagellates, chrysophytes, and prymnesiophytes). 

 The most abundant accessory pigments detected in this study 

 were chlorophyll c, diadinoxanthin, and fucoxanthin (Table 2), 

 which reflect the dominance of diatoms in the Gulf of Anadyr 

 and the Chukchi Sea during midsummer. In addition, the suite 

 of pigments also common to the diatoms (chlorophyllide «, 

 diatoxanthin, and p,P-carotene) all displayed elevated 

 concentrations in these regions. Distributions of chlorophyll b 

 and peridinin indicate that green algae and dinofiagellate 

 abundances were highest in a band extending from just north of 

 St. Lawrence Island, through the Bering Strait, and into the 

 Chukchi Sea. These distributional patterns are consistent with 

 those described by Kisselev ( 1937 ), who found that these algal 

 groups were abundant in the northern Bering Sea. 

 1 9'-Hexanoyloxyfucoxanthin and 1 9'-butanoyloxyfucoxanthin 

 concentrations were highest in waters overlying the Chirikov 

 basin (located just north of St. Lawrence Island)and the central 

 and southern regions of the Bering Sea, reflecting the presence 

 of prymnesiophytes and chrysophytes, respectively; 

 concentrations of these pigments were near the limit of HPLC 

 detection at stations occupied in the Chukchi Sea. 



In summary, pigment concentrations in the Bering and 

 Chukchi Seas were complex and variable and suggest that 

 phytoplankton are not uniformly distributed with respect to 

 both biomass and composition. A comparison of these 

 distribution patterns with concurrently measured physico- 

 chemical parameters (i.e., nutrients and currents) will provide 

 insight into the factors affecting phytoplankton abundance in 

 the Bering and Chukchi Seas. 



Fig. 1 . Contours of chlorophyll (J ( ng'l ' ) measured in Ihe Bering and Chukchi 

 Seas during July-August 1988, aboard the R/V Akculemik Korulev. 



Fig. 2. Contours of chlorophyllide a (ng-1 ') measured in the Bering and 

 Chukchi Seas during July-August 1988. aboard the RA' Akademik 

 Korolev. 



129 



