when wetlands were lost at a rate of 185,000 hectares per year. This improvement, however, cannot be considered satisfactory, because the United States continues to lose wetlands at a rate of at least 1 percent per year in spite of mitigation and restoration attempts. The poor-quality wetlands that result from many mitigation and restoration efforts are no substitute for the lost habitats, processes, and functions of natural wetlands. Serious consequences have resulted nationwide from the loss and degradation of wetlands, including species decline and extinction, water quality deterioration, and increased incidence of flooding.
The need for enhanced interaction among the subdisciplines of aquatic science is nowhere more evident than in the area of applying this science to management and conservation of freshwater resources. In fact, knowledge from other disciplines (including social science and education) is necessary to improve the ability to address challenges of management, mitigation, and perpetuation of aquatic resources. The fact that aquatic science favors an ecosystem approach demands this interdisciplinary perspective—one that includes humans as an ecosystem component to be considered in nearly every applied strategy.
Specific aquatic science technology and research needs are too many to list but include such disparate subjects as on-site waste disposal systems, the relationship between macrophyte beds and fish production, the role of nitrogen in macrophyte growth, bioaccumulation, wetland functions, transport and deposition of toxics, waterborne pathogens, buffer zones, best-management practices, control of exotic species, water quality reference sites, and ecological risk assessments. Organizing these and many other needs, prioritizing them, and then tackling them with well-designed research is a daunting responsibility, but it is crucial to the perpetuation of aquatic resources.
The field of conservation biology has promulgated the construct of coarse filter and fine filter in order to advance biodiversity conservation (Noss, 1987; Hunter, 1990). This approach is used by the Nature Conservancy to address management issues ranging from endangered species to ecosystem perpetuation (Hudson, 1991). Hunter (1990) provided a lucid description of this approach. The coarse-filter approach to perpetuating biodiversity involves maintaining a variety of ecosystems, and assuming that this will include the majority of species in a region. The fine-filter approach is used in the case of individual species known to be very rare and vulnerable to ''passing through" the coarse filter. A perpetual dilemma in applied aquatic ecosystem science is the need to proceed with management activities despite the lack of complete knowledge required to solve a particular resource problem. Given this reality, the fine- and