Southern Ocean Planning

## GLOBEC International Southern Ocean Planning

### by Eileen Hofmann

The unique characteristics of the Antarctic marine food web make the Southern Ocean an ideal environment in which to test many of the GLOBEC core hypotheses that consider the effects of variability in the physical environment on population dynamics. Consequently, U.S. GLOBEC and GLOBEC International have identified the Southern Ocean as a potential site to conduct research on the response of the marine ecosystem to climate change. Given the nature of Antarctic research, any GLOBEC initiative in the Southern Ocean will be international in scope, making it natural that GLOBEC International should take the lead in the organization and planning of a Southern Ocean GLOBEC program.

From 15 to 17 June 1993, the first meeting of the International GLOBEC Southern Ocean Planning Group was held at the Center for Coastal Physical Oceanography of the Old Dominion University in Norfolk, VA. This meeting was convened under the auspices of the GLOBEC International program and was attended by 26 scientists who represented 9 nations and the Intergovernmental Oceanographic Commission (IOC). The goals of the meeting were to define key questions and the framework to be used as a basis for the development of an implementation plan for an international Southern Ocean GLOBEC program.

The first day of the meeting consisted of several overview presentations. The first of these reviewed recommendations from earlier GLOBEC efforts that were relevant to the goals of the Southern Ocean meeting, such as the U.S. GLOBEC Southern Ocean Workshop held in 1991 and the report of the GLOBEC Working Group on Population Dynamics and Physical Variability. Following this, presentations were given on physical processes as related to site selection, animal physiology and distribution as related to the Southern Ocean marine food web, fish and krill distributions, marine bird and mammal distributions, and technology capabilities, especially in regard to satellites. Following the overview presentations, the meeting participants divided into working groups which met on the second and third days. At the end of each day, a plenary session was convened for a discussion of the recommendations from the working groups. Each working group prepared a summary report of the group discussions.

The working groups were structured to focus on population dynamics and physical variability, historical data and data management, sampling and observation systems and modeling. The population dynamics and physical variability working group was subdivided into groups that focused on issues relating to zooplankton, top predators, and interactions between zooplankton and top predators. These working groups were tasked with developing key questions that could be used as a basis for an implementation plan for a Southern Ocean GLOBEC program.

Key questions for GLOBEC-related zooplankton research in the Southern Ocean focused on: overwintering strategies; seasonal and geographical distributions, especially in relation to the environment; factors affecting successful reproduction; physical factors affecting larval survival and recruitment; and the distribution of Southern Ocean zooplankton in relation to the distribution of biomass and reproduction. Key zooplankton species selected for a Southern Ocean GLOBEC program are: Euphausia superba, Calanoides acutus, and Metridia gerlachei. However, the scientific basis of a Southern Ocean program should be broad enough to accommodate research on other zooplankton species, as needed.

The top predator working group identified as key questions: effects of variability in the physical environment on predator populations; the role of sea-ice in affecting top predator populations; krill variability and its allocation among several top predator species; the effect of predator foraging activity on krill distribution; and the nature of the functional relationships between krill availability and performance and survival of its predators. The primary top predator key species for a Southern Ocean program were identified as Crabeater seals, Adelie penguins, Snow petrels, Antarctic petrels, fish, and squid.

The joint zooplankton-top predator working group put forward recommendations on how to structure research programs that include organisms from zooplankton to large mammals, which encompass a wide range of space and time scales. The historical data and data management working group and the modeling working group made specific recommendations that were designed to encourage the use of historical data bases and the development of models for the Southern Ocean prior to a field program, respectively. The sampling and observation working group focused on the need to better incorporate and use remote sensing techniques for studying zooplankton and top predator populations.

The report from the Southern Ocean Planning Meeting will be available from the GLOBEC International Planning Office in late fall 1993 as part of their report series. A second meeting of the Southern Ocean Planning Group is planned for April or May 1994. The objectives of this meeting will be to develop an implementation plan for a Southern Ocean GLOBEC program. The likely venue for this meeting will be Cambridge, England. (Eileen Hofmann is a member of the GLOBEC.INT Southern Ocean Planning Group and chair of the U.S. GLOBEC Southern Ocean Committee)