for fishing and swimming. Contaminated runoff from expanding urban and agricultural areas, airborne pollutants, and hydrologic modifications such as drainage of wetlands are just a few of the many factors that continue to degrade U.S. surface waters despite reductions in sewage and industrial waste discharges. Determining which of these factors has the most significant influence on the quality of a water body requires knowledge about how the water body interacts with its watershed and airshed and how the various inputs affect its physical, chemical, and biological characteristics.

One of the critical sciences required to understand these freshwater interactions is called limnology (from the Greek limne, meaning pool or marshy lake). As defined in this report and other recent reports on the field, limnology includes the study of lakes, reservoirs, rivers, and freshwater wetlands (Edmondson, 1994; Lewis, 1995; Lewis et al., 1995). It is a multidisciplinary science that draws from all the basic sciences relevant to understanding the physical, chemical, and biological behavior of freshwater bodies. There are numerous subspecialties of limnology based on the application of fundamental sciences such as physics, chemistry, geology, and biology; branches of physical science such as optics, fluid mechanics, and heat transfer; and branches of biological science such as microbiology, botany, ichthyology, invertebrate zoology, and ecology. Limnology integrates these other sciences in order to study inland waters as ecological systems (Edmondson, 1994; Lewis, 1995). In a recent essay entitled ''What Is Limnology?" limnologist W. T. Edmondson (1994) described limnology as

the study of inland waters … as systems. It is a multidisciplinary field that involves all the sciences that can be brought to bear on the understanding of such waters: the physical, chemical, earth, and biological sciences, and mathematics.

Limnology thus has two distinguishing features: it is an integrative (i.e., interdisciplinary) science, and it consists of many component subspecialties (i.e., it is multidisciplinary). The interdisciplinary, multidisciplinary nature of limnology provides a broad perspective that is critical in identifying the multiple sources of stress that may prevent a water body from serving its essential functions.

Although advances in limnology can play a critical role in improving the quality of fresh surface waters, prominent limnologists have expressed concern that the field is in decline (Naiman et al., 1995). Some have cited lack of a national research budget devoted to limnology (Jumars, 1990), others have identified lack of adequate educational programs (Wetzel, 1991), and still others have suggested inadequate attention by academic limnologists to contemporary environmental problems (Kalff, 1991) as the reasons for this decline. In a recent assessment of the status of limnology,

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