Freshwater is vital to human life and societal well-being, but society has frequently not recognized the full value of healthy rivers, lakes, groundwater, and wetlands. There has been growing recognition that intact aquatic ecosystems provide many economically valuable services and long-term benefits to society, in addition to the provision of water. A new Ecological Society of America position paper explains the basis for sustaining freshwater ecosystems and details ways to go about reconciling ecosystem and human needs. The paper, "Meeting Ecological and Societal Needs for Freshwater," addresses the complicated question of how society can extract the water resources that it needs while sustaining freshwater ecosystems. ESA offers a series of recommendations for how water should be viewed and managed, and how aquatic ecosystems can be protected or restored. These include incorporating freshwater ecosystem needs into national and regional water management policies, defining water resources to include watersheds, and increasing communication and education across disciplines.
The paper states that it is in the long-term economic interest of society to work to protect and restore freshwater ecosystems. The benefits of healthy freshwater systems include food supply, flood control, purification of human and industrial wastes, and habitat for plant and animal lifeall of which are costly, if not impossible, to replace with technological infrastructure. The sustained provision of those goods and services, as well as the adaptive capacity of aquatic ecosystems to respond to future environmental alterations such as climate change, is critical to human well-being.
Natural freshwater ecosystems are dynamic, and therefore require a range of natural variation or disturbance to maintain their function. Human intervention, such as the building of dams, often narrows the range of variability, in turn causing changes in the ecosystem. For example, since the completion of the Glen Canyon Dam in 1963, measurable flows of the Colorado River to its mouth at the Gulf of California have occurred only six times, and the wetland area at the mouth of the river has decreased markedly as well. The lack of freshwater inflows has contributed to the endangerment of a large number of species in the Sea of Cortez, and the abundance of bivalve mollusk populations has dropped 94 percent from 1950 values. Water temperature can also change dramatically downstream of dams. Declines in the variability of monthly temperature along with reductions in species richness have been observed in the downstream waters of some dams in the western states. All these changes have ripple effects throughout ecosystems. For example, since they are filter feeders that remove many of the pollutants found in water, a decline in mollusks can lead to dirtier water, which can in turn threaten the well-being of other species.
Tools are available to restore aquatic ecosystems to a more natural and sustainable state, but are not being widely applied, according to the ESA paper. New statistical approaches to develop variable stream flows while still meeting hydroelectric and water supply needs have been applied or proposed for only several rivers, including the Flathead River in Montana, and the Colorado River. Variable streamflow techniques seek a compromise between water delivery needs for power generation or irrigation, and aquatic ecological needs for hydrological variability.
"The problems confronting freshwater ecosystems are intractable if they are approached piecemeal," said ESA President Pamela Matson of Stanford University. "This position paper makes it clear that the needs of society and of freshwater ecosystems must be addressed collectively. Politically, this requires broad coalitions of water users working together toward a mutually acceptable future," said Matson.
Founded in 1915, the Ecological Society of America (ESA) is a scientific, non-profit, organization with over 7500 members. Through ESA reports, journals, membership research, and expert testimony to Congress, ESA seeks to promote the responsible application of ecological data and principles to the solution of environmental problems. For more information about the Society and its activities, access ESA’s web site at: http://www.esa.org.
Source: Ecological Society Of America. February 2002