PRINCIPAL INVESTIGATORS:

J. D. Schumacher (Two Crow Environmental Consultants)

P. J. Stabeno (Pacific Marine Environmental Laboratory)

R. D. Brodeur and J. M. Napp (Alaska Fisheries Science Center)

G. L. Hunt (University of California, Irvine).

OBJECTIVES:

The objectives of this project are to: monitor biophysical features of the ecosystem, and develop ecosystem health indices that predict the survival-potential of young pollock.

RATIONALE:

We have witnessed unprecedented changes in the Bering Sea Ecosystem over the past several years. Documented change in the biological and physical elements of this system have occurred at the same time as financially catastrophic returns of some Bering Sea salmon runs and high mortalities by some apex predators. Previous to this many others (stakeholders, public officials, and research scientists) have publicly warned that the Bering Sea ecosystem was showing signs of stress (Larry Merculief - the Southwest Alaska Municipal Conference, Fisheries Committee Workshop, 30 January 1998, Anchorage, AK., and The Bering Sea Ecosystem Workshop, 4-5 December, 1997, Anchorage, AK and Deborah Williams, Special Assistant to the Secretary of Interior for the State of Alaska -- In Report of the Bering Sea Ecosystem Workshop, 1998). It is

within this context that our monitoring and indices project operates. We are the only currently funded project that is committed to long-term monitoring and analysis of biophysical conditions over a broad range of habitats in the southeastern Bering Sea and as such the data we have collected will be invaluable in understanding the mechanisms that are changing the Bering Sea.

SCIENTIFIC ACCOMPLISHMENTS:

The Monitoring and Indices (MI) component of SEBSCC (together with cooperative research conducted by the National Science Foundationís Inner Front Study), collected observations which provide the basic description of a recent and dramatic shift in the physical, chemical and biological status of the southeastern Bering Sea in the last two years (Appendix I). We (the SEBSCC & NSF investigators) have observed and documented dramatic changes in: wind-driven mixing over the shelf (1997, anomalously low; spring 1998, anomalously high), summertime sea surface temperatures (1997, 4^oC positive anomaly; 1998, early summer only slightly warmer than normal, late summer unknown), mixed layer depth (1997, shallower than normal; 1998, not yet determined), spring phytoplankton bloom (1997, typical ice edge bloom in timing and magnitude; 1998, anomalously late), summer nutrient reservoir concentrations (1997 anomalously low; 1998, not yet determined). Concomitant with these changes have been catastrophically low returns of Bristol Bay sockeye salmon (1997 and 1998), anomalously high mortalities of an apex predator, the short-tailed shearwater (1997, 1998 to be determined), massive coccolithophore blooms covering the southeastern shelf during summer and fall (1997 and 1998). In addition, the initial estimates of age-0 pollock during the summer of 1998 are lower than estimates obtained over the previous three years.

In our proposal, we contracted to: (1) collect observations of the ecosystem, (2) process and quality control these data, (3) develop and test indices of the status of the ecosystem with particular focus on the survival-potential of larval and young of the year pollock. To date, MI Principal Investigators have participated in 139 days at sea (14 cruises), deployed 23 moorings with a suite of physical and biological sensors, and collected biophysical data at over 200 discrete stations, and CTD data at hundreds more stations. The majority of these are processed.

We have identified several features of the ecosystem which are candidate indices of status of the Bering Sea. Among these are:

1. The extent of ice and its influence on the timing of the phytoplankton bloom and hence the succession of bottom-up mechanisms which must match in time and space the needs of first feeding pollock larvae,
2. Winds which influence the ecosystem through mixing (MLD was markedly shallow in summer 1997) and by advection as direct wind-driven flow. The latter may increase the separation between early life history stages and their cannabalistic parents since recent evidence suggests that many larvae over the shelf may be in water depths less than 10 m. The timing of storms also play a role in the intensity of stratification over the middle shelf and the depletion of nutrients in the cold pool.
3. The concentration of nutrients retained in the bottom layer of the middle shelf (essential for prolonged production at the inner front),
4. The species composition of phytoplankton (i.e., the coccolithophorid bloom which has occurred in 1997 and 1998) http://www.pmel.noaa.gov/card/stabeno/true_color.jpg
5. The location, strength and stability (eddies) of the ANSC/BSC system which impacts the advection of nutrients and pollock larvae onto the shelf, and
6. The increased presence of previously low abundance biota (e.g., jellyfish and coccolithophorids; http://www.pmel.noaa.gov/~miletta/images/jellyfish.gif).

We have met the commitments made in this proposal.

APPLICATIONS:

Papers and presentations based primarily on MI observations or using these data with a focus on other aspects of the ecosystem are listed below. MI PI s also played a central role in the development of a Draft Bering Sea Ecosystem Research Plan. This document will be used to guide research funded by the North Pacific Research Board.

Publications:

Brodeur, R. D., M. T. Wilson, and L. Ciannelli. Spatial and temporal variability in feeding and condition of age-0 walleye pollock in frontal regions of the Bering Sea. ICES J. Mar. Sci., to be submitted.

R.D. Brodeur, C.E. Mills, J.E. Overland, and G.E. Walters. 1998. Evidence for a recent increase in jellyfish in the Bering Sea, with possible links to climate change. To be submitted to Nature. Presented at Oceanography Society Meeting in Paris, France, June 1998.

Hunt, G. L., Jr. and G. V. Byrd, Jr. Climate change, carrying capacity and marine bird populations of the eastern Bering Sea. In: The Bering Sea: Physical, Chemical, and Biological Dynamics. Loughlin, T. R., and K. Ohtani (eds.), Alaska Sea Grant Press, submitted.

Hunt, Jr., G. L., C. L. Baduini, C. T. Baier, R. D. Brodeur, K. O. Coyle, M. B. Decker, K. D. Hyrenbach, V. M. Mendenhall, J. M. Napp, S. Salo, J. D. Schumacher, P. J. Stabeno, D. A. Stockwell, C. T. Tynan, T. C. Vance, T. E. Whitledge, S. I. Zeeman. Ecosystem Response to Anomalous Conditions in the Bering Sea: An omen of climate change? Science, submitted.

Napp, J. M., R. D. Brodeur, D. Demer, R. Hewitt, P. J. Stabeno, G. L. Hunt Jr., and J. D. Schumacher. Observations of nekton, zooplankton and seabird distributions at tidally generated shelf fronts in the eastern Bering sea. Mar. Ecol. Prog. Ser., submitted.

Schabetsberger, R., R. D. Brodeur, L. Ciannelli, J. M. Napp, and G. L. Swartzman. MS. Diel vertical migration and interaction of zooplankton and micronekton at a frontal region near the Pribilof Islands, Bering Sea. (To be submitted to ICES Journal of Marine Science).

Stabeno, P. J., N. A. Bond, N. Kachel, S. Salo and J. D. Schumacher, Anomalous Conditions in the Bering Sea during 1997, (to be submitted to Fish. Ocean.)

Swartzman, G., R. D. Brodeur, J. M. Napp, G. Hunt, D. Demer, and R. Hewitt. MS. Spatial proximity of age-0 walleye pollock to their plankton prey near the Pribilof Islands, Bering Sea, Alaska. ICES Journal of Marine Science, submitted.

In Press

Brodeur, R. D., M. T. Wilson, G. E. Walters, and I.V. Melnikov. In Press. Forage fishes in the Bering Sea: Distribution, species associations, and biomass trends. In: Loughlin, T. R. and K. Ohtani (eds.) The Bering Sea: Physical, Chemical, and Biological Dynamics. Univ. of Alaska Sea Grant, in press

Brodeur, R. D., M. Doyle, J. M. Napp, P. J. Stabeno, J. D. Schumacher, and M. T. Wilson. 1998. Fronts and fish: Interannual and regional differences in frontal structure and effects on pollock and their prey. Oceanogr., In press.

Lang, G. M., R. D. Brodeur, J. M. Napp, and R. Schabetsberger. Variation in groundfish predation on juvenile walleye pollock relative to hydrographic structure near the Pribilof Islands, Alaska. ICES J. Mar. Sci., In press.

Logerwell, E. A, Hewitt R, Demer, D. A. Scale-dependent spatial variance patterns and correlation of seabirds and prey in the southeastern Bering Sea as revealed by spectral analysis. Ecography, in press

Schumacher, J. D., and P. J. Stabeno. The continental shelf of the Bering Sea. In: The Sea, Vol. XI. The Global Coastal Ocean: Regional Studies and Synthesis. John Wiley, Inc. New York. in press.

Stabeno, P. J., J. D. Schumacher, S. A. Salo, M. Flint and G. L. Hunt, Jr. The Physical environment around the Pribilof Islands. In: The Bering Sea: Physical, Chemical, and Biological Dynamics. Loughlin, T. R., and K. Ohtani (eds.), Alaska Sea Grant Press, in press.

Stabeno, P. J., J. D. Schumacher, and K. Ohtani. The physical environment of the Bering Sea. In: The Bering Sea: Physical, Chemical, and Biological Dynamics. Loughlin, T. R., and K. Ohtani (eds.), Alaska Sea Grant Press, in press.

Sugisaki, H., R. D. Brodeur, J. M. Napp. Summer distribution and abundance of macrozooplankton in the western Gulf of Alaska and southeast Bering Sea. Mem. Fac. Fish. Hokkaido Univ., in press

Published

Brodeur, R. D. 1998. In situ observations of the association between juvenile fishes and scyphomedusae in the Bering Sea. Mar. Ecol. Prog. Ser. 163:11 20.

Brodeur, R. D., M. T. Wilson, J. M. Napp, P. J. Stabeno, and S. Salo. 1997. Distribution of juvenile pollock relative to frontal structure near the Pribilof Islands, Bering Sea. Proc. Int. Symp. on the Role of Forage Fishes in Marine Ecosystems, Alaska Sea Grant AK-97-01. p. 573-589.

Ciannelli, L., R. D. Brodeur, and T.W. Buckley. 1998. Development and application of a bioenergetics model for juvenile walleye pollock. J. Fish Biol. 52: 879-898.

Schumacher, J. D., P. J. Stabeno, N. A. and J. M. Napp, 1998. Ecosystem Anomalies in the Eastern Bering Sea During 1997. N. Pac. Anadromous Fish Comm. Tech. Report, Workshop on Climate Change and Salmon Production, Vancouver, Canada: pp. 44-46.

Stabeno, P. J., 1998. The status of the Bering Sea in the second half of 1997. In: PICES Press, Vol. 6(#2): pp.8-10, 29.

Stabeno, P. J., 1998. The status of the Bering Sea in the first eight months of 1997. In: PICES Press, Vol. 6(#1): pp.8-11.

Stabeno, P. J. 1997. The status of the Bering Sea in the second half of 1996. In: PICES Press, Vol. 5, 2, 14-15

Stabeno, P. J., J. D. Schumacher, R. F. Davis, and J. M. Napp, 1998. Under-ice observations of water column temperature, salinity and spring phytoplankton dynamics: Eastern Bering Sea shelf, 1995. J. Mar. Res., 56:239-255.

Vance, T. C., C. T. Baier, R. D. Brodeur, K. O. Coyle, M. B. Decker, G. L. Hunt Jr., J. M. Napp, J. D. Schumacher, P. J. Stabeno, D. Stockwell, C. T. Tynan, T. E. Whitledge, T. Wyllie-Echeverria and S. Zeeman. Anomalies in the Ecosystem of the Eastern Bering Sea: Including Blooms, Birds and Other Biota. Trans. Amer. Geophys. Union, EOS 79: 122-126.

Presentations:

Baier, C. T. and J. M. Napp. Springtime Distribution and Gonadal Maturity of Calanus marshallae Over the Southeastern Bering Sea Shelf. AGU/ASLO Ocean Sciences Meeting, February 1998, San Diego, CA

Brodeur, R., M. Wilson, P. Stabeno, J. Napp, and J. Schumacher. Distribution of juvenile pollock relative to frontal structure near the Pribilof Islands, Bering Sea. PICES Annual Meeting, Nanaimo, BC. (Recipient of Best Paper Award), October 1996.

Brodeur, R. In situ observations of the association between juvenile fishes and scyphomedusae in the Bering Sea. International Symposium on the Role of Forage Fishes in Marine Ecosystems, Anchorage, AK, November 1996.

Brodeur, R., M. Wilson, P. Stabeno, J. Napp, and S. Salo. Distribution of juvenile pollock relative to frontal structure near the Pribilof Islands, Bering Sea. International Symposium on the Role of Forage Fishes in Marine Ecosystems, Anchorage, AK., November 1996.

Brodeur, R. FOCI ecosystem-related juvenile pollock studies. PFMC Ecosystem Workshop, Seattle, WA, January 1997.

Brodeur, R. Spatial and temporal variability in feeding and condition of age-0 walleye pollock in frontal regions of the Bering Sea. ICES Recruitment Symposium, Baltimore, MD, September, 1997.

Hunt, G. L., K. O. Coyle, J. D. Schumacher, P. J. Stabeno, D. Stockwell, T .Whitledge, S. Zeeman. Ecosystem Anomalies in the Eastern Bering Sea: Seabird Dieoff and Coccolithophorid Bloom Follow Calm Spring and Strong Stratification. AGU/ASLO Ocean Sciences Meeting, February 1998, San Diego, CA

Napp, J. M., C. T. Baier, A.W. Kendall, Jr., and J. D. Schumacher. Biophysical factors that affect larval pollock survival and prey production over the southeastern Bering Sea shelf. International Workshop on Ecosystems of the North Pacific, 17 July 1998, Seattle WA, USA.

Napp, J. M., C. T. Baier, R. D. Brodeur, J. J. Cullen, R. F. Davis, M. B. Decker, J. J. Goering, C. E. Mills, J. D. Schumacher, S. Smith, P. J. Stabeno, T. C. Vance, and T. E.

Bloom: Ecosystem Observations and Hypotheses. AGU/ASLO Ocean Sciences Meeting, February 1998, San Diego, CA., EOS, Trans. Am. Geophys. Union, Vol. 79, p. 127.

Schumacher, J. D., P J Stabeno, N A Bond, T Wyllie-Echeverria. Ecosystem Anomalies in the Eastern Bering Sea: Observations of the Physical Environment During 1997. AGU/ASLO Ocean Sciences Meeting, February 1998, San Diego, CA

Schumacher, J. D., Invited. Is the light yellow or red, a Mother Ocean mystery. Southwest Alaska Municipal Conference; Fisheries Committee Workshop, 30 January 1998, Anchorage, AK.

Schumacher, J. D. Invited. Ecosystem Anomalies in the Eastern Bering Sea During 1997. N. Pac. Anadromous Fish Comm. Workshop on Climate Change and Salmon Production, 26-27 March 1998, Vancouver, Canada.

Schumacher, J. D. Invited. OAR research in the eastern Bering Sea; recent results. The Bering Sea Ecosystem Meeting, 4-5 December, 1997, Anchorage, AK.

Stabeno, P. J. and J. D. Schumacher. Observations of the Physical Environment During 1997. NSF Workshop 20-21 November, 1997, Seattle, WA.

Stabeno, P. J. Measurements of the physical environment of the Bering Sea, GLOBEC SSC, April 1998, Washington DC.

Stabeno, P. J. The Greenbelt, ARI Workshop, October 1997, Seattle WA.

SEBSCC Workshop Synthesis of Monitoring Results, 15-16 December 1997, Seattle, WA.

Steps to Completion :

Chlorophyll, Nutrients, and Zooplankton Status: All 1997 samples have been analyzed. Because the last cruise does not take until September 1998, chlorophyll and nutrient sample analysis will be completed during the first quarter of FY99. Zooplankton samples from the first half of the field season have been shipped to Poland for analysis. It is expected that all zooplankton data will become available for quality control and analysis during the third quarter of FY99.

CTD and mooring data: All data collected at this point has been processed. The data collected in September and October will be processed by the second quarter of FY99. All mooring data from 1997 has been processed. The data from moorings recovered in October will be processed by the end of the first quarter of FY99.

Planned Journal Articles:

There are a series of articles to be published in Fisheries Oceanography describing the anomalous conditions in 1997 will be submitted 1st or 2nd quarter FY99.

Manuscript describing patterns in zooplankton community composition around the Pribilof Islands (1994 and 1997) to be submitted by 4th quarter of FY99.

Manuscript with preliminary analysis of springtime prey production by Calanus marshallae to be submitted by 4th quarter FY99.

All manuscript preparation to be funded by (we hope) Phase II SEBSCC Monitoring and Indices.
 
 
 

Appendix I

During summer 1997, a large portion of the eastern shelf of the Bering Sea experienced an anomalous bloom of coccolithophorids (Vance et al., 1998; Stabeno 1998). This feature was first observed as aquamarine waters from ships during July. The bloom was also clearly visible from space, as shown by some of the first images from the multi-spectral Sea-viewing Wide-Field-of-view Sensor (SeaWiFS) scanner in September and observed by astronauts in the space shuttle in August. Between August and September, reports of moribund and dead short-tailed shearwaters came from biologists and the public

on both sides of the Alaska Peninsula including Bristol Bay. The sockeye salmon run in Bristol Bay was far below expectation: an estimated 5-12 million animals failed to appear in the fishery which was declared a "commercial failure" (Fisheries, 1998). At the same time, significant numbers of large baleen whales were observed foraging within the milky waters (Tynan, 1998). Chlorophyll-a concentrations during the bloom (Fig. 1) were low in agreement with such blooms in other regions of the world (e.g., North Sea, Gulf or Maine). The tiny phytoplankton cells contain little chlorophyll-a or particulate organic carbon, but they make a large impact on water color. Concomitant with these changes in the biological environment, anomalous conditions were evident in many of the features of the physical environment.

The anomolously warm SST (http://www.pmel.noaa.gov/card/stabeno/temp.html) signal observed in the Bering Sea resulted from regional wind mixing and heat exchange with atmosphere rather than propagation of an oceanic anomaly from the equator. As occurred in recent years (Stabeno et al., 1998), an early spring diatom bloom ( about 12 mg/m3) was associated with sea ice (Napp et al., 1998). By the end of April, chlorophyll concentrations had decreased to pre-bloom values. During April winds were unusually weak and these conditions generally persisted through August. The anomaly in wind speed cubed (a proxy for mixing), follows the same general pattern as the winds (Fig. 2). A striking mixing event, however, did occur in mid-May. The impact of this storm was to mix the upper 40-45 m, thereby making nutrients from the lower layer available in the upper water column. This reduced the reservoir of nutrients typically found throughout the summer in the lower layer (Napp et al. 1998). The storm also weakened the pycnocline, which permitted further depletion of nutrients. This likely occurred through both a vertical flux of nutrients across the pycnocline to the surface and net photosynthesis below the mixed layer throughout the summer. An examination of heat content revealed that it was similar to that in the previous year. The heat, however, was concentrated in a shallow mixed layer. The extreme SST anomalies appear to be due primarily to the lack of winds rather than to increased solar radiation resulting from reduced cloud cover. This warm upper layer extended over portions of the coastal domain into waters as shallow as 30 m. In general, the coastal domain waters are mixed. One consequence was that the transition between coastal and middle shelf water was poorly defined and tens of kilometers wider than previously reported (Schumacher and Stabeno, in press). The changes in structure likely affected the usual biophysical dynamics which result in primary and secondary production throughout summer.

While biophysical processes likely account for much of the nutrient depletion on the shelf, a change in the flux from source waters may have exacerbated this situation. Observations of temperature and salinity versus depth were collected several along a slope/shelf transect. In spring 1997, transport in both the Aleutian north Slope Current (ANSC) and the Bering Slope Current (BSC) was unusually large, > 6 x 10 6 m3 s-1 whereas transport is typically <3 x 10 6 m3 s-1. Moored current records from the ANSC revealed consistent flow, supporting the inference of steady, strong flow during 1997. How the enhanced strength of these currents affects shelf/slope exchange is not known. The flux of oceanic water through Bering Canyon is a source of nutrients for the shelf (Schumacher and Stabeno, in press). During 1997, satellite tracked drifters revealed that little or no onshelf flow occurred there also.

Whether a part of an decadal cycle or of human induced global change, the arctic climate is warming. Observations from Alaska confirm this, for example a long-term warming trend of 0.75 C per decade occurred from 1961-1990 (Chapman and Walsh, 1993) with an accompanying warming of the discontinuous permafrost in the Bering Sea region and some thawing from top to bottom (Osterkamp, 1994). A group of scientists convened in 1995 to hypothesize physical change in the Bering Sea under a global warming scenario (US GLOBEC, 1996). Among the changes they forecast were that wind mixing energy, the supply of nutrients and ice extent and thickness would decrease and sea surface temperature would increase. The physical conditions observed during 1997 in the eastern Bering Sea fit these predicted changes well. The associated changes in biota, however, at present defy forecasting since knowledge of biophysical process, system time lags and life histories of many of the important species is lacking

Figures

1. Time series of concentration of chlorophyll-a at Site 2. Note the spring bloom in early April and the gradual increase during summer. The blooms in September followed storms. (These data are preliminary). http://www.pmel.noaa.gov/card/stabeno/ice.html

2. Time series of the anomaly of the daily wind speed cubed using observation form St. Paul Island. Note the event in mid-May. The mean was defined as the daily average wind speed cubed from 1950-1996. http://www.pmel.noaa.gov/card/stabeno/wind.ht

References (Other than those listed in Applications)

Bering Sea Ecosystem Workshop, 1998. Report of Workshop 4-5 December, 1997, Anchorage, AK. For copies contact Pat ivingston, AFSC: pliving@afsc.noaa.gov).

Chapman W. L. And J. E. Walsh, 1993. Recent variations of sea ice and air temperatures in high latitudes. Bull. Am. Meteorology Society 74(1): 33-47.

Fisheries, 1998. NMFS declares commercial fisheries failure in Alaska's Bristol Bay salmon fishery. Fisheries, Vol. 2, p.2.

Osterkamp, T. E., 1994. Evidence for warming and thawing of discontinuous permafrost in Alaska. EOS, Trans. Am. Geophys. Union 75(44): 85.

Tynan, C. T., 1998. Redistribution of cetaceans in the southeast Bering Sea relative to anomalous oceanographic conditions during the 1997 El Nino. Abstract, The World Marine Mammal Science Conference, Monaco, January 20-24, 1998, Symposium on Marine Mammals and Oceanographic Processes, p. 138.

U. S. GLOBEC, 1996. Report on Climate Change and Carrying Capacity of the North Pacific Ecosystem, Scientific Steering Committee Coordination Office, Dept. Integrative Biology, Univ. Calif., Berkeley, CA, U. S. GLOBEC Rep. #15, 95 pp.