• Conduct cruises to observe ecosystem dynamics associated with the spring bloom of phytoplankton.

The purpose of these cruises was to investigate the spring phytoplankton bloom and its associated physical, chemical, and biological oceanographic processes. The southeastern Bering Sea is a major center for the primary production that supports higher trophic levels. The renewal and dispersal of nutrients by physical processes and regeneration by organic decomposition is balanced by physical stratification and phytoplankton uptake as the seasons progress from winter to summer. Cruise objectives were to recover and deploy moorings at sites #2, #3, #4, and #6 and to conduct biological and physical sampling using net tows and CTD casts at and between mooring sites. All moorings were successfully recovered, and only one instrument out of fifty failed. Surface mooring #2 broke loose from its anchor on June 11 and was recovered by WECOMA one week later. The mooring was transported to Kodiak for refurbishing and redeployed from the Canadian Ice Breaker SIR WILFRID LAURIER in July.  Minor mechanical problems prohibited net tows during one cruise, and abnormally severe weather impeded many operations throughout the spring.  Specific cruise reports for MF98-05B, W98-04D, W98-05A, and W98-06B may be viewed at http://www.pmel.noaa.gov/foci/operations/instructions/1998/contents.html.

Despite these operational setbacks, spring conditions were well documented. Seasonal sea ice advanced as far as the middle shelf, but retreated in February, long before there was sufficient radiation to trigger an ice-edge bloom.  Inflow into the Bering Sea occurred on the western side of Amchitka Pass, rather than the eastern side. A large clockwise eddy appeared during early April and continues to affect the Bering Slope Current.   Temperatures in the southeastern Bering Sea were warmer than previous years, and there was more storm activity. Thermal stratification was less pronounced as a result. A recognizable spring phytoplankton bloom had not started by mid May, and by mid June there was still no spring bloom evident in either the middle or outer shelf domains. A spring bloom did occur over the inner shelf.  Anomalous conditions prevail again this summer with a second year's coccolithophore bloom covering much of the eastern Bering Sea shelf (see http://rho.pmel.noaa.gov/vance/seawifs/bering.html).