## Introduction

U.S. GLOBEC is a global change research program concerned with the impact of global climate variability and climate change on the dynamics of marine ecosystems, specifically with the impact upon animal populations. It aims to sufficiently understand ocean ecosystem dynamics and how they are influenced by physical processes to be able to predict the response of the ecosystem and the stability of the food web to climate change. Physical processes strongly influence ecosystem dynamics in the sea. U.S. GLOBEC focuses primarily on the linkages between physical forcing variables and the dynamics of the planktonic stages of marine organisms, which are presumed to be the most vulnerable to changes in physical forcing associated with climate change. Target species include both the holoplankton, species resident in the plankton throughout their life cycle, and the meroplankton (including ichthyoplankton), which are planktonic for only a fraction of their life cycle and for the remainder are either benthic or nektonic. Moreover, changes in plankton populations can critically affect the distribution, abundance and maintenance of living marine resources.

Physical processes, structures and characteristics in the ocean change when climate variability or climate forcing change. These modifications in physical pattern and process impact the distribution, abundances and dynamics of animal populations in the sea. U.S. GLOBEC will examine biological responses to existing natural climatic forcing in order to provide predictions of how future climatically-driven physical forcing and potential anthropogenic changes impact the marine ecosystem. U.S. GLOBEC must consider scales ranging from the very small to the planetary. Examples of large-scale considerations include (but are not limited to): 1) regional intercomparison of generic ecosystem types; 2) the basin scale linkages of regional ecosystems; and, 3) the dynamics of zoogeographic boundaries.

The importance of multidisciplinary research in ocean science was recognized more than half a century ago by pioneering ocean scientists such as F.E. Bigelow and H.U. Sverdrup. Only now are the individual disciplines (physical, biological and chemical oceanography) sufficiently advanced so that physical, biological and chemical processes can be sampled on the same temporal and spatial scales. While U.S. GLOBEC focuses upon zooplankton, understanding of zooplankton dynamics requires concomitant knowledge of phytoplankton populations and processes and the dynamics of biogeochemical cycles. These are the focus of the U.S. JGOFS program, and U.S. GLOBEC will collaborate and interact with U.S. JGOFS as closely and efficiently as possible. U.S. GLOBEC will also benefit from cooperation with GLOBEC International and other global change research programs [e.g., Inter-American Institute for Global Change Research (IAI), Land-Ocean Interactions in the Coastal Zone (LOICZ), Past Global Changes (PAGES), and Global Change and Terrestrial Ecosystems (GCTE)]. U.S. GLOBEC research results will eventually be used to direct the development of a system for monitoring and management of living marine resources in a changing climate. Such a system would include both an observational network and a data assimilative operational model. It would be an invaluable component of the Global Ocean Observing System (GOOS).

The scientific origin of U.S. GLOBEC is rooted in the inherently, interdisciplinary formulation of modern ocean science and its ongoing interest in living marine resources. The beginning of the present program is, however, associated with the NSF, NOAA and ONR sponsored Wintergreen meeting of 1988 which led to the formation of the Scientific Steering Committee in 1989. The U.S. GLOBEC program is organized around a number of inter-related elements and activities including process-oriented field programs, modeling, retrospective studies, environmental monitoring, technology development and exchange of scientific information. U.S. GLOBEC research is supported by the U.S. National Science Foundation-Division of Ocean Sciences and Office of Polar Programs, and by the U.S. National Oceanic and Atmospheric AdministrationÑOffice of Global Programs, National Marine Fisheries Service, and Coastal Ocean Program. It is a component of the U.S. Global Change Research Program. A bibliography of U.S. GLOBEC program reports is in Appendix B.