Overview of the Inner Front and Southeast Bering Sea Carrying Capacity Programs

Deep-Sea Research II 49 (2002) 6157–6168 Overview of the Inner Front and Southeast Bering Sea Carrying Capacity Programs Phyllis J. Stabeno a, *, George L. Hunt Jr. b a Pacific Marine Environmental Laboratory, NOAA, 7600 Sand Point Way NE, Seattle, WA 98115-6349, USA b Department of Ecology and Evolutionary Biology, University California, Irvine, Irvine, CA 92697, USA 1. Introduction During the 1990s, there has been a signiﬁcant increase in our understanding of the Bering Sea ecosystem. Two programs, NOAA’s Coastal Ocean’s Southeast Bering Sea Carrying Capacity (SEBSCC) and the National Science Foundation- supported Inner Front Program (IFP), led the way in new ﬁndings. SEBSCC, whose focus was on the middle and outer shelves, and the slope, and IFP, whose focus was on the inner shelf, complemented each other. Several scientists, including the authors of this paper, were investigators in both programs. This resulted in close collaboration between the programs, a sharing of ship time, data, and ideas, and culminated in the compilation of this volume. Between 1995 and 2000, we had the good fortune to be studying the Bering Sea during a period of great variability. We were presented with the opportunity to study an extremely warm year (1997) and a cold year (1999). During the 1990s, there were other marked changes in the Bering Sea shelf ecosystem including extensive blooms of coccolithophores, increases in jellyﬁsh, and the appearance of large baleen whales. We also observed a massive die off of shearwaters, the continued decline in northern fur seals (Callorhinus ursinus) and Steller sea lions (Eumetopus jubatus), and a sharp decrease in the number of salmon. *Corresponding author. Tel.: +206-526-6453. E-mail addresses: stabeno@pmel.noaa.gov (P.J. Stabeno), glhunt@uci.edu (G.L. Hunt Jr.). 0967-0645/02/$ - see front matter Published by Elsevier Science Ltd. PII: S 0 9 6 7 - 0 6 4 5 ( 0 2 ) 0 0 3 3 9 - 9 These changes in the ecosystem, together with advances in ocean technology, provided the opportunity to expand our understanding of this complex ecosystem. In this paper we summarize the major ﬁndings of the two programs, starting with the physical environment, progressing through primary production, and ﬁnally discuss- ing upper trophic levels. We then discuss a new hypothesis (Hunt et al., 2002) that links ecosystem function to climate. In closing, we pose several questions that remain unanswered and suggest directions for future research. 2. Decadal variability The Bering Sea is characterized by large year-to- year variability, but is also sensitive to climate changes on decadal and longer time scales (Over- land et al., 1999; Stabeno et al., 2001). It has been only within the last 10 years that signiﬁcant research has been done on decadal-scale variability of climate and how it impacts the eastern Bering Sea ecosystem. The Bering Sea responds to two dominant decadal oscillations, the Paciﬁc Decadal Oscillation (PDO) and the Arctic Oscillation (AO) (Overland et al., 1999). The PDO is the ﬁrst mode of decadal variability in the sea-surface tempera- ture of the North Paciﬁc and its major impact is in the North Paciﬁc and the southern Bering Sea. Changes in ﬁsh populations and other ecosystem functions are correlated with oscillations in the PDO (Mantua et al., 1997; Hare and Mantua,