![[logo] US EPA](../gif/logo_epaseal.gif){kind=logo}
Assessing Water Quality: An Energetic Perspective
Tingting Cai 1, Thomas W. Olsen 2, Sherry Brandt-Williams 1, and Dan E. Campbell 1
1 USEPA, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, Narragansett, RI 02882
2 Kingston, RI 02881
Integrated measures of food web dynamics could serve as important supplemental indicators of water quality that are well related with ecological integrity and environmental well-being. When the concern is a well-characterized pollutant (posing an established risk to human health), a direct measure of this pollutant's concentration could be an efficient and reliable indicator. In other cases, the viability or prevalence of specific populations known to be sensitive to certain classes of more general or less understood impairments could be most useful. Concerns with ecological integrity, however, upon which the long-term viability of the biotic community depends, require a more integrated measure related to community metabolism. Ecosystem and community energy/emergy fluxes provide possible measures of vigor and long-term viability that might help relate a more empirically developed index of biotic integrity to the processes supporting ecological integrity (in terms of the energy flows that drive them). In the proposed approach, sites are characterized by their energy signatures (or influx attributes), with expected community energy acquisition rate providing a standard for assessing ecological integrity with respect to a reference energy influx regime. Application of the approach will depend on adequately specifying the relation between energy acquisition rate and long-term community viability under a given energy signature, the relation between changes in the emergy signature of a water body that alter food web energetics and changes in water quality that affect bioindicators (such as an index of biotic integrity), and the factors affecting these relations.
Keywords: water quality assessment, biological indicators, ecological integrity, emergy signature