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 764 Interaction of ice and biota seasonal pulses in primary production (Walsh et al. 1978). However, the system differs from that in the New York Bight, for example, in that the ice attenu- ates mixing and wind stirring, thereby increasing the effects of water column stability both in enhancing the phytoplankton bloom and in limiting nutrient replenishment. METHODS A series of cruises was conducted at the ice edge from May 15
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 764 Interaction of ice and biota seasonal pulses in primary production (Walsh et al. 1978). However, the system differs from that in the New York Bight, for example, in that the ice attenu- ates mixing and wind stirring, thereby increasing the effects of water column stability both in enhancing the phytoplankton bloom and in limiting nutrient replenishment. METHODS A series of cruises was conducted at the ice edge from May 15 to June 9 in 1975, from March 14 to April 30 in 1976, and from April 7 to June 11 in 1977. The strategy employed was to occupy stations at intervals of about 10 km along courses roughly perpendicular to the ice edge, extending into the ice when possible and away from the ice for about 50 km. Standard hydrographical sampling using Series 9000 Plessy CTD systems was done at each station. The data obtained were calibrated using in-situ water samples. Chlorophyll a was measured by ex- tracting particulate material collected on micropore glass filters in 90 percent acetone over a 24-hour period and reading the absorbance of the extract vdth a Beckman DU spectrophotometer. In 1977 fluores- cence of the extract was determined with a Turner fluorometer. RESULTS Ice-edge hydrography The dramatic fluctuations in sea temperatures and southern extent of the ice on the eastern Bering Sea shelf as related to anomalous weather patterns have been outlined by Niebauer (1980; Chapters 3 and 9, Volume 1). We are concerned here with the effect of these fluctuations on the hydrographic sections of the ice edge collected on cruises in late May 1975 and late March-early April 1976 and 1977. In May 1975, sea-surface temperatures (SST) around the Pribilof Islands were ~ C below normal at ~ C, and the ice cover was about 15 percent above the normal coverage 30-35 percent (Niebauer 1980). The posi-
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