Scientists with a wide range of expertise participated in a workshop to design the U.S. field program contribution to the Global Ocean Ecosystems Dynamics (GLOBEC) Southern Ocean program and to provide guidance to the National Science Foundation (NSF) on how the U.S. may contribute to the GLOBEC Southern Ocean (SO GLOBEC) program.

The twenty scientists met with representatives from the Office of Polar Programs and the Division of Ocean Sciences on Sept. 30-Oct. 1, 1998 at the NSF in Arlington, VA. Early discussion focused on the SO GLOBEC science and implementation plans, stressing the importance of international cooperation and understanding interactions between physical forcing and biological responses in the marine environment.

Year-round studies and austral winter observations to meet SO GLOBEC objectives were emphasized, and krill (Euphausia superba) remains the research target species for SO GLOBEC. Workshop participants agreed upon the pressing need to understand krill ecology in the broader context of habitat preferences, feeding ecology, and interactions with its predators and competitors. Subsequent presentations at the meeting dealt more specifically with aspects of krill ecology as they are currently understood.

Zooplankton Science Questions: What key factors affect the successful reproduction of krill between seasons ?? What key physical processes influence krill larval survival and subsequent recruitment to the adult population between seasons ?? What are krill's seasonal food requirements with respect to energetic needs and distribution and type of food ?? What are the geographical variations in krill distribution in relation to the between- and within-season variability in the physical environment ??

Predator Science Questions: How does the winter distribution and foraging ecology of krill-dependent predators relate to the characteristics of the physical environment and the distribution of their prey ?? How does summer breeding season foraging ecology relate to the abundance and distribution of the available krill population ?? How does year-to-year variability in predator population size and breeding success relate to sea ice extent and its possible effects on krill recruitment, availability, and distribution ??

One workshop presentation reviewed recent studies documenting the importance of krill-sea ice interactions in structuring the Antarctic marine ecosystem. Emphasis was placed on the importance of winter sea ice as critical habitat to Antarctic krill and the significant role that salps may play as krill competitors during the non-winter months.

Next, strong linkages between the foraging ecology of Adelie penguins, krill recruitment success, and sea ice cycles in the western Antarctic Peninsula region were outlined. The extreme sensitivity of these krill predators to changes in krill availability was illustrated. Thus, the ecological dynamics of krill predators can be employed as proxy measures in field studies seeking understanding of how physical forcing cascades through the food web.

A third presentation reviewed present knowledge of the hydrography and circulation of the west Antarctic Peninsula continental shelf. The hypothesis was put forward that the mesoscale gyres now known to occur along this Peninsula shelf may serve as important krill retention areas in this region. In addition, the importance of the Circumpolar Deep Water in mediating regional-scale sea ice formation was proposed and supporting data presented. The last two presentations provided overviews of the NOAA Antarctic Marine Living Resources program and of potential interactions between SO GLOBEC and the International Whaling Commission (IWC).

Workshop participants acknowledged the apparent cohesion between the data supporting the various presentations. Participants also agreed that SO GLOBEC has the potential to provide some critical elements in our emerging understanding of ecosystem dynamics in the western Antarctic Peninsula region.

Following the presentations, workshop participants formed two working groups to focus on habitat variability and predator-prey interactions. The key science questions are noted below:

Outcomes

The two primary results of the workshop were: 1) the U.S. SO GLOBEC program will focus on winter studies and 2) the study site will be moved to the region near Marguerite Bay.

Elements of SO GLOBEC

Southern Ocean GLOBEC will focus on Antarctic krill as the primary target species, including the habitat, prey, predators, and competitors of this species. The SO GLOBEC program will be a year-round study, with emphasis on austral winter processes. Recent evidence indicates that seasonal coverage is necessary to fully understand the linkages between the environment, krill, and top predators.

Working groups dealing with questions related to Habitat Variability and Predator-Prey Dynamics met to determine the elements of studies in these critical research areas. For a report of these working groups, click HERE.

Study Site

The primary field effort for SO GLOBEC is scheduled to begin in 2000/2001 and will focus on two critical sites: the western Antarctic Peninsula and Prydz Bay (70 E) regions. The western Antarctic Peninsula region will be studied through a multi-nation, multi-ship effort in order to obtain seasonal coverage, especially in the austral winter. Studies in the Prydz Bay region will be seasonal.

The U.S. contribution will be field studies in the western Antarctic Peninsula region. The International SO GLOBEC Planning Group recommended a region near Anvers Island as the field study site for the Antarctic Peninsula program. This site has both krill and krill-dependent predator populations, is subject to seasonal ice coverage, and may be a region of low advective flow.

At the U.S. SO GLOBEC workshop, it was decided to move the field study site further south along the western Antarctic Peninsula to a region in the vicinity of Marguerite Bay. The Anvers Island site could be a source of retrospective, comparative data. Careful consideration of winter predator distributions and the hydrography and circulation of the Marguerite Bay region suggest that this area would better meet the science objectives of SO GLOBEC. For example, there is evidence that large numbers of krill-dependent predators (e.g., penguins, seals, and whales) winter in the Marguerite Bay area, suggesting the presence of a depend-able food source such as krill. Also, there is evidence of a recirculating gyre in this region and evidence of Circumpolar Deep Water upwelling. The latter is warmer and may produce dependable regions of open water in winter.

Some workshop participants thought that this change could compromise the international collaborations necessary to obtain the year-round coverage desired by SO GLOBEC. However, sampling nearer to Marguerite Bay will enhance cooperation with the British Antarctic Survey (BAS) and the BAS land-based station at Rothera. Winter sampling in Marguerite Bay was also an issue. An analysis of ice conditions in this region, using satellite archives, should be undertaken to establish the winter ice conditions.

Retrospective Studies

Retrospective studies need to be an integral part of SO GLOBEC. Analyses of data reservoirs, archives and as yet unanalyzed samples could provide answers to some of the questions for which multi-year data are needed. This analyses could also be used to optimize the overall experimental design associated with the single-year SO GLOBEC program by identifying the truly essential data needed to fill critical ecological gaps.

Timing of U.S. SO GLOBEC Program

The announcement of opportunity for the U.S. Southern Ocean GLOBEC program will be drafted and, after approval by the appropriate groups in the NSF, it will be released to the community in early 1999. Proposals submitted in response to this announcement of opportunity will be due at the NSF Office of Polar Programs by 1 June 1999. Peer review and NSF review of these proposals will take place during summer 1999. Awards will be made in Fall 1999 for a field program that will take place in austral winter (May-September 2001). Proposals that focus on modeling and retrospective data analysis will also be solicited as part of the announcement of opportunity.

Coordination with the International SO GLOBEC Program

The U.S. Southern Ocean GLOBEC program is part of a larger international effort. Therefore, it is important that the U.S. program be coordinated with field activities in other nations, such as Germany and the United Kingdom. This will be done through regional planning meetings to be scheduled for March to April 1999.

An important aspect of the success of SO GLOBEC is obtaining year-round coverage in a region. A tentative ship schedule (see chart) has been developed that will provide the needed coverage.

Other activities related to SO GLOBEC are being undertaken as part of the Modeling and Data Management working groups that have been appointed by the chair of the International GLOBEC program. These working groups include participants from the U.S. SO GLOBEC community.

Coordination with the International Whaling Commission (IWC)

The IWC indicated that understanding climate change effects on cetaceans is an area of emphasis and has initiated linkages to programs such as SO GLOBEC. The IWC is developing a Southern Ocean Whale Ecosystem Research (SOWER) program and desires that a component of this program to be a joint field effort with SO GLOBEC. The IWC thus plans to place observers on SO GLOBEC ships to conduct tagging studies of individual whales and mesoscale surveys around the SO GLOBEC study area. The intent will be to bridge the smaller scales over which cetaceans feed with the larger scales over which cetaceans are distributed, and which are currently the subject of IWC research via the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Some IWC funding and ship resources have already been allocated for participation in SO GLOBEC. The use of these resources will be determined in a series of planning workshops scheduled over the next year.

Coordination with CCAMLR

SO GLOBEC will take place the year following the CCAMLR Area 48 Synoptic Survey, and it is anticipated that observations, especially of krill, from this survey will be available to help plan the SO GLOBEC western Antarctic Peninsula study. Also desirable is to have CCAMLR parti-cipation directly in SO GLOBEC. SO GLOBEC will require participation by many groups and nations in order to provide year-round coverage of the western Antarctic Peninsula region. The opportunity exists for CCAMLR to provide part of this coverage and such participation would be welcome from SO GLOBEC.

AWI: Alfred Wegener Institute CCAMLR: Commission for Conservation of Antarctic Marine Living Resources US: United States Southern Ocean GLOBEC BAS: British Antarctic Survey

Proposed Cruise Coverage for Southern Ocean GLOBEC December 2000 - January 2002

Dec. '00

Jan. '01

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Jan. '02

AWI

CCA MLR

CCA MLR

CCA MLR

US

US

US

US

US

US

BAS

BAS

tba

tba

Coordinated by Suam Kim

Approx. 6 weeks in this 3 month period

Approx. 6 weeks in this 3 month period