Abstract
Two Bering Sea marine research programs collaborated during the final years of the 1990s to forge advances in understanding the southeastern Bering Sea pelagic ecosystem. Southeast Bering Sea Carrying Capacity, sponsored by NOAA Coastal Ocean Program, investigated processes on the middle and outer shelf and the continental slope. The Inner Front Program, sponsored by NSF, investigated processes of the inner domain and the front between the inner and middle domains. The purposes of these programs were to (1) increase understanding of the southeastern Bering Sea ecosystem, including the roles of juvenile walleye pollock, (2) investigate the hypothesis that elevated primary production at the inner front provides a summer-long energy source for the food web, and (3) develop and test annual indices of pre-recruit pollock abundance. The observations occurred during a period of unusually large variability in the marine climate, including a possible regime shift. Sea-ice cover ranged from near zero to one of the heaviest ice years in recent decades. Sea-surface temperatures reached record highs during summer 1997, whereas 1999 was noted for its low Bering Sea temperatures. Moreover, the first recorded observations of coccolithophore blooms on the shelf were realized in 1997, and these blooms now appear to be persistent. The programs' results include an archive of physical and biological time series that emphasize large year-to-year regional variability, and an Oscillating Control Hypothesis that relates marine productivity to climate forcing. Further investigations are needed of the confluences of interannual and even intra-seasonal variability with low-frequency climate variability as potential producers of major, abrupt changes in the southeastern Bering Sea ecosystem.
Highlights
The Bering Sea (511–661N, 1571W–1631E) is a unique laboratory for many ocean processes
The sea surface is ice covered for a significant portion of the year
In addition to the seasonal ice cover restricting vertical fluxes there, the accumulation of freshwater in the North Pacific creates a vertical density gradient that serves as a lid that inhibits vertical mixing
Summary
The Bering Sea (511–661N, 1571W–1631E) is a unique laboratory for many ocean processes. Very cold and dry air masses from Siberia can move over the Bering Sea where massive amounts of heat and water can be extracted Changes in these fluxes can have remote consequences on the atmosphere through global teleconnections. The Bering Sea contains abundant biological resources, including many species of fish, shellfish, seabirds, and marine mammals. Over the last few decades, some species of fish, shellfish, seabirds, and marine mammals have experienced significant fluctuations in abundance. Such changes have brought awareness of our relative ignorance in understanding the ecosystem and raised the need for research geared to promote better management of regional living resources. With a better understanding of climate variability that might accompany improved measurements and the possibility of lowfrequency climate changes at high latitudes, the value of these studies should increase
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