Abstract
In virtually every major environmental act, Congress has required that the U.S. Environmental Protection Agency (U.S. EPA) ensure not only that the air be safe to breathe, the water safe to drink, and the food supply free of contamination, but also that the environment be protected. In response, the U.S. EPA's Office of Research and Development (ORD) has established research to improve ecosystem risk assessment and management, identifying it as one of the highest priority research areas for investment over the next 10 years. The research is intended to provide environmental managers with new tools and flexible guidance that reflect a holistic environmental management perspective of science and that can be applied both to common and unique problems. In keeping with its responsibility to provide the U.S. EPA with science that supports a dynamic changing regulatory agenda, the ORD has set the goal of its Ecological Research Program to βprovide the scientific understanding required to measure, model, maintain and/or restore, at multiple scales, the integrity and sustainability of ecosystems now, and in the future.β In the context of this program, ecological integrity is defined in relative terms as the maintenance of ecosystem structure and function characteristic of a reference condition deemed appropriate for its use by society, and sustainability is defined as the ability of an ecosystem to maintain relative ecological integrity into the future. Therefore, the research program will emphasize relative risk and consider the impact of multiple stressors, at multiple scales and at multiple levels of biological organization. The program will also shift from chemical to biological and physical stressors to a far greater extent than in the past. The purpose of this paper is to provide an introduction to the U.S. EPA's changing ecological research program.