Collaborative Research: WinDSSOcK: Winter Distribution and Success of Southern Ocean Krill

Old Dominion University Research Foundation, Norfolk VA

Investigators

Abstract

This project is a contribution to a coordinated attempt to understand the interactions of biological and physical dynamics by developing relationships among the evolution of the antarctic winter ice and snow cover, biological habitat variability, and the seasonal progression of marine ecological processes. The work will be carried out in the context of the Southern Ocean Experiment of the Global Ocean Ecosystem Dynamics Study (Globec), a large, multi-investigator study of the winter survival strategy of krill under the antarctic sea ice in the vicinity of Marguerite Bay on the western side of the Antarctic Peninsula. There are two aspects to this project: the characterization of the regional hydrography, and the development of a hierarchy of models to organize and integrate the physical and biological observations. The water masses on the continental shelf off Marguerite Bay consist of inflowing Upper Circumpolar Deep Water, which is relatively warm, salty, oxygen-poor, and nutrient-rich. In winter atmospheric processes cool and freshen this water, and recharge it with oxygen to produce Antarctic Surface Water which is diffused seaward, and supports both a sea ice cover and a productive krill-based food web. This project will define these water masses with repeated regional temperature, salinity, nutrients, and oxygen surveys, supplemented by a moored current meter and temperature array, and by acoustic surveys to observe the upper ocean current structure. The modeling effort will provide a mechanism to link water column and sea ice processes with the biology of krill and its predators. It will further help to link these winter observations to similar observations made in summer and elsewhere around Antarctic in the international context of the Globec program. Three major types of models will be used to order the various observations: (1) time-dependent biological models - e.g. species interaction models; (2) depth-time models of both physical and biological characteristics - e.g. effect of snow, ice, and water turbidity on the distribution of light, and (3) three-dimensional and time-dependent models synthesizing physical and biological models over the continental shelf. The specific objective is to develop a comprehensive ecosystem in order to test our understanding of the system, determine its sensitivities, and to provide an organizing mechanism for integrating the Southern Ocean Globec observations. ***