The proposed research addresses the overarching question: are marine food webs leading to fisheries controlled from the top-down, the bottom up, or a combination of the two? To address this question we will (1) compare end-to-end energy budgets of the 4 US-GLOBEC study regions in the context of top-down v. bottom-up forcing, (2) assess the skills of the regional models in capturing basic material fluxes, (3) extract diagnostics from the regional models that will be used to evaluate the effects of climate change and fishing pressure across GLOBEC regions and (4) develop quantitative methods to compare the diagnostics. The major successes of GLOBEC have been in elucidating the processes underlying the dynamics of individual species in ecosystems characterized by diverse physical settings. At the same time there is an increasing demand for an ecosystem approach to management of marine resources subject to fishing pressures and climatic changes. Improving the understanding of trophic links in oceanic food webs is integral to the ability to understand and predict ecosystem responses to climate change and anthropogenic forcings. The use of state-of-the-art modeling approaches coupled to data assembly and analyses provides opportunities to train graduate students (3 included in project) in a variety of disciplines (food web modeling, data analyses, data assimilation, marine ecology) that are needed to address the important scientific and societal problems facing marine systems. The project includes 2 postdoctoral scientists, many women (9 of 22 investigators) including several in lead roles, several talented young scientists new to GLOBEC, other scientists new to GLOBEC, and an outstanding team of international collaborators (see Letter of Support from BAS). The cooperative effort among scientists from academia, government, and private industry is beneficial to all groups. The management plan centered on intensive, frequent communication via in-person, digital and electronic meetings is a unique and potentially transformative aspect of the project.