The Eastern Bering Sea Shelf The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder easternberingsea00hood Year: 1981 940 Plankton ecology nutrient content is indeed lower in areas covered by sea ice, then ice may actually lower the annual pro- ductivity of these areas. Ice cover thus appears to be much more important in regulating the seasonal timing of phytoplankton growth than in enhancing annual productivity. Stage-I Bering Sea phytoplankton are adapted to grow under conditions of low light, high nutrients, and cold temperatures (Bering Sea
The Eastern Bering Sea Shelf The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder easternberingsea00hood Year: 1981 940 Plankton ecology nutrient content is indeed lower in areas covered by sea ice, then ice may actually lower the annual pro- ductivity of these areas. Ice cover thus appears to be much more important in regulating the seasonal timing of phytoplankton growth than in enhancing annual productivity. Stage-I Bering Sea phytoplankton are adapted to grow under conditions of low light, high nutrients, and cold temperatures (Bering Sea surface tempera- tures 1-3 C, NO3-N -20-25 mM, Si(OH'*)-Si -40-50 juM: see Goering and Iverson 1978, Iverson et al., 1979a and b). These first-stage plants also seem to escape heavy predation, although small zooplankton such as Pseudocalanus spp. and Acartia longiremis winter in the mid-shelf region as adults and must feed on phytoplankton before reproducing (Cooney and Geist 1978, Alexander and Cooney 1979). The small diatoms of the genera Thalassiosira and Chae- toceros dominate stage-I Bering Sea phytoplankton numbers (Fig. 56-4). Total community cell division STATIONS 62 64 rates are about per day and cell densities reach 10^-10^/m^ (Goering and Iverson 1978, Iverson et al. 1979b). Cylindropyxis temulens, Thalassio- sira gravida, and Prorocentrum spp. have also been reported as stage-I successional members (Alexander and Cooney 1979). Phaeocystis poucheti in certain regions, especially near the mid-shelf and outer shelf fronts, also appears to be a stage-I species in the Bering Sea (Fig. 56-4). Raymont (1963) has reported that Phaeocystis grows well at high phosphate and nitrate levels, a condition present in the Bering Sea during stage-I successional development. Its growth rate at cold temperatures has not been determined. During the spring when Bering Sea temperatures are low, the colonial haptophyte Phaeocystis com- petes favorably with diatoms, and early in the sp
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