a much better idea of how to price a decrease in a system’s ability to produce fish for a commercial fishery than a decrease in a system’s ability to provide socioeconomic stability to small, rural communities. Furthermore, even when services can be measured, policymakers will have to prioritize among restoration options because of resource limitations. The first scenario raises concerns that more-difficult-to-price services will be discounted or ignored in decision making; the second highlights an important limitation to any approach to remediation.
The committee concludes that the key to feasible application of an ecosystem services approach is the development of tools capable of establishing and quantifying causal links among the event, an injury to an ecosystem, the resulting decrease in goods and services provided by that system, and the cost of that decreased production of goods and services to individual communities and society at large.
WHAT ARE ECOSYSTEM SERVICES?
Society benefits from a wide variety of resources and processes that are provided by ecosystems. These benefits are known as ecosystem services, and they result from the functioning of an ecosystem—the interactions of plants, animals, and microbes with the environment (NRC, 2011).
A rich and evolving literature on ecosystem services offers a variety of definitions of ecosystem services (e.g., Barbier, 1994; Costanza et al., 1997; Daily, 1997; de Groot, 1987; de Groot et al., 2002; Ehrlich and Mooney, 1983; EPA, 2009; MEA, 2005; NRC, 2005b; TEEB, 2010; Westman, 1977; Wilson and Carpenter, 1999). The common thread through all of these definitions is the concept of a relationship between ecosystems and the value humans derive from them. In 2000, the United Nations commissioned the Millennium Ecosystem Assessment (MEA) to summarize the current status and future conditions of biodiversity and ecosystems, and to describe the consequences of ecosystem change for human well-being, including secure livelihoods, social cohesion, security, and freedom of choice and action (MEA, 2005).
The MEA defines ecosystem services as “the benefits provided by ecosystems to humans, which contribute to making human life both possible and worth living” (MEA, 2005, p. 23). Moreover, the MEA defines explicit categories of ecosystem services, including:
• Provisioning services (e.g., material goods such as food, feed, fuel, and fiber);
• Regulating services (e.g., climate regulation, flood control, water purification);
• Cultural services (e.g., recreational, spiritual, aesthetic); and
• Supporting services (e.g., nutrient cycling, primary production, soil formation).
These service categories are now widely accepted and form the basis for the discussion of ecosystem services throughout this report. When applied to the GoM, discussions of ecosystem services must take into account the geographic, oceanographic, ecological, and social context of the GoM. Details of the GoM ecosystem and the regional context for the GoM were presented in the committee’s Interim Report (NRC, 2011).