2
Limnology, the Science of Inland Waters: Evolution and Current Status

The origins of limnology date back many centuries to a time when scientists were called natural philosophers and science was explored by a few, usually wealthy, individuals. For example, Gorham (1953) traced the development of wetland ecology and some of its fundamental premises to studies of British natural philosophers going back to the fifteenth and sixteenth centuries. Similarly, Hutchinson (1967) traced studies on lakes at least as far back as a fifteenth century study on the ponds of a European abbey. However, the evolution of limnology into a modern science depended on the development of concepts and tools in biology, chemistry, and physics that were not available until the late nineteenth century.

Although modern limnology encompasses the study of all inland waters, its development is particularly identified with the study of lakes. Much of the conceptual framework around which the science was built was derived from studies on lakes, and most of the early limnologists were lake scientists. A notable exception was Stephen Forbes, a principal architect of the framework for limnology who was trained as a fish biologist and spent most of his career working on rivers and streams in Illinois, a state with relatively few natural lakes. It is understandable why early limnologists focused on lakes. As systems with easily recognizable boundaries and long residence times for water and substances in it, they are more obvious subjects for systematic scientific analysis than are the open, flowing waters of streams and spatially less defined wetlands. Nonetheless, it must be noted that the historical treatment usually accorded to limnology is colored by the fact that it generally is written by lake scientists,



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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology 2 Limnology, the Science of Inland Waters: Evolution and Current Status The origins of limnology date back many centuries to a time when scientists were called natural philosophers and science was explored by a few, usually wealthy, individuals. For example, Gorham (1953) traced the development of wetland ecology and some of its fundamental premises to studies of British natural philosophers going back to the fifteenth and sixteenth centuries. Similarly, Hutchinson (1967) traced studies on lakes at least as far back as a fifteenth century study on the ponds of a European abbey. However, the evolution of limnology into a modern science depended on the development of concepts and tools in biology, chemistry, and physics that were not available until the late nineteenth century. Although modern limnology encompasses the study of all inland waters, its development is particularly identified with the study of lakes. Much of the conceptual framework around which the science was built was derived from studies on lakes, and most of the early limnologists were lake scientists. A notable exception was Stephen Forbes, a principal architect of the framework for limnology who was trained as a fish biologist and spent most of his career working on rivers and streams in Illinois, a state with relatively few natural lakes. It is understandable why early limnologists focused on lakes. As systems with easily recognizable boundaries and long residence times for water and substances in it, they are more obvious subjects for systematic scientific analysis than are the open, flowing waters of streams and spatially less defined wetlands. Nonetheless, it must be noted that the historical treatment usually accorded to limnology is colored by the fact that it generally is written by lake scientists,

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology even though scientific studies on flowing waters and wetlands in some cases predate studies on lakes. Even today, many aquatic scientists in North America associate the word limnology with the study of lakes (and reservoirs). To the extent that there is any general awareness of the word limnology, this perception applies to the public as well. There are historical reasons for this situation, but it has caused difficulties in coalescing the various branches of limnology into a more coordinated and organized science. This chapter traces the history of the study of lakes, reservoirs, rivers, and wetlands. It includes biographical sketches of some of the individuals (limnologists as well as other scientists) who have contributed to the understanding of inland aquatic ecosystems and significantly influenced the field of limnology. The chapter concludes with an analysis of the current status of limnology with special reference to professional and educational issues in the United States. EARLY HISTORY The beginnings of limnology as a modern science usually are traced to the work of a few late nineteenth century biologists who focused on lake studies. The founders of lacustrine limnology defined the scope and nature of the field in a way that survives remarkably intact to the present day; they viewed the subject broadly and integratively. Francois Forel (see Box 2-1) was the first scientist to use the term limnology in a publication. His three-volume treatise on Lake Geneva (bordered by Switzerland and France), published over the period 1892 to 1904, is considered the first book on limnology, and it was encyclopedic in scope. Its 14 chapters define the main supporting fields of modern lake limnology (Edmondson, 1994) and reinforce the idea that lake limnology is the application of all relevant basic sciences to the analysis of lakes as fundamental units of study. The integrative nature of limnology was stressed even before Forel coined the term limnology. In a prescient article published in 1887, Stephen Forbes (Box 2-2) described lakes as ''microcosms," or little worlds. Although the term "ecosystem" was not introduced for another half century (Tansley, 1935), Forbes defined an approach that presaged this concept. He proposed that lake studies should focus on many of the processes that today define the field of ecosystem ecology: mineral cycling, production and decomposition of organic matter, food web interactions and their impacts on the structure of biological communities, and the effects of physical conditions on biological communities. Forbes viewed these topics as essential to understanding lakes as functioning, integrated systems. The notion of lakes as microcosms (or integrated ecosystems) has pervaded their study ever since Forbes' time, even though the concept has

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology BOX 2-1 FRANCOIS ALPHONSE FOREL (1841–1912) Francois A. Forel invented the word limnology. The science would have been called "limnography," to match its sister science oceanography, had it not been for the priority of reserving the term "limnograph" for a device used to measure water height in lakes. Forel was born in Morzes on the shore of Lake Geneva (known to the Swiss as Lac Leman). When he was 13, his father introduced him to "… the art of observing and questioning nature,'' according to a monograph that he later wrote about Lake Geneva (Forel, 1882, 1895, 1904). After graduating from the Academie de Geneve, Forbes completed a medical degree at Würzburg and taught there for three years. In 1870, he joined the faculty of the Academie de Lausanne, where he taught anatomy and physiology and started a lifelong study of Lake Geneva. One of Forel's earliest observations connected the physical, chemical, and biological properties of Lake Geneva. While looking to see if waves had left ripple marks on the bottom along the shore, he noticed a wriggling nematode in a sample of mud. This "poor worm" piqued his curiosity and led him to invent a bottom dredge with which he discovered that the depths of the lake were not a desert but were occupied by a specialized fauna rich in species and individuals. His studies resulted in a long series of influential papers on benthic fauna, their environmental conditions, and their significance to the fish population; the papers were consistent with modern concepts of ecosystem ecology. He followed with comparative work on other Swiss lakes. In physical limnology, much of Forel's attention focused on water oscillations that create standing wave patterns, known to limnologists as seiches. In addition to obtaining massive data on Lake Geneva itself, he studied movements of water in small, tilted model lake basins, thus anticipating by many years a kind of experimental limnology. From these studies he developed generalizations about the relations between the dimensions of lakes and the periodicity of their seiches. He also conducted pioneering work in other aspects of physical limnology, devising a color scale and studying light penetration with photographic paper, and considered external influences on the lake, particularly the relation of the water supply to glaciers. Henri LeBlanc (1912) listed Forel's publications in categories: limnology (126 titles), glaciology (66), seismology (12), meteorology (19), natural history (28), archaeology (12), history (10), and biographies (15). The massive Lake Geneva monograph Le Leman: Monographie Limnologique was published in three volumes in 1882, 1895, and 1904, with a total of 14 chapters. A small textbook appeared in 1901. He continued to work until a few months before his death in 1912, producing about 35 percent of his publications after the appearance of the last volume of the monograph in 1904.

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology BOX 2-2 STEPHEN ALFRED FORBES (1844–1930) … [A] little world within itself—a microcosm within which all the elemental forces are at work and the play of life goes on in full but on so small a scale as to bring it easily within the mental grasp. This is how Stephen Forbes described the ecological dynamics of a lake in his often-cited 1887 paper "The Lake as a Microcosm." In this early essay, Forbes described the now familiar concept of the interdependence of living organisms and environmental factors. Owing much to Forbes' influence, the field of limnology developed a strong ecological perspective by the close of the nineteenth century. Born in 1844 in Silver Creek, Illinois, Forbes was raised on a farm with five siblings. At age 17, he joined the Union cavalry and served four years during the Civil War, including four months as a prisoner of war. After the war, he studied medicine, but within three years he turned to natural history. He attended Illinois State Normal University for a brief time but continued natural history studies on his own. In 1872, Forbes became curator of the Museum of the State Natural History Society in Normal, Illinois; in 1877, he transformed this institution into the Illinois State Laboratory of Natural History. In 1884, he moved with the laboratory and museum to Urbana, became a professor at the University of Illinois, and completed a Ph.D. from Indiana University. He was chief of the Illinois State Natural History Survey until his death in 1930. The limnological contributions of Forbes were diverse. He was among the first to study North American inland lakes (other than the Great Lakes). His studies of several lakes in the Rocky Mountains, published in 1893, represented for a number of years the sole biological information on lakes in the western United States. Forbes was an early and notable contributor to limnology of running waters as well; under his direction, the Illinois State Laboratory of Natural History established a floating laboratory on the Illinois River and conducted an extensive, half-century-long study of the river. In "The Lake as a Microcosm," Forbes fostered the idea that the organisms and dynamics of a water body are isolated from and independent of the landscape. Although today this concept has been supplemented by current understandings about the influence of the catchment basin and airshed, Forbes' cogent view contributed a significant organizing model. The notion of the lake as a microcosm (that is, an isolated, simplified, and understandable system) provided impetus and encouragement for scientists to study lakes from an "ecosystem" standpoint (even though the term ecosystem was not introduced until 1935). The lake as microcosm persists as a vital concept in limnology today. It has inspired studies at all scales, from whole lake to plastic pool and small aquarium, as limnologists have endeavored to understand the components, functions, and interactions of aquatic systems.

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology BOX 2-3 EDWARD A. BIRGE (1851–1950), CHANCEY JUDAY (1871–1944), AND THE WISCONSIN SCHOOL OF LIMNOLOGY Birge and Juday are usually included among the founders of limnology. Their research contributed substantially to the basic understanding of a broad range of physical, chemical, and biological characteristics of lakes. They also assisted the development of the field through their roles in initiating a strong educational program and communications networks linking professional limnologists. Several books provide details of their lives (Sellery, 1956; Frey, 1963; Beckel, 1987). The contributions of Birge and Juday represent a microcosm of the interdisciplinary links that have been essential for progress in limnology. Both began their work with classic zoological studies on the taxonomy and distribution of a major component of lake planktonic communities, the cladocerans. They soon found, however, that little could be understood about the distribution of these animals in lakes without evaluating a range of physical and chemical properties. This led to investigations of water column thermal structure, distribution of dissolved gases, and light penetration, along with the mechanisms controlling these features. Several fundamental aspects of lakes that now comprise a basic component of most modern investigations derive from these efforts (Mortimer, 1956; Frey, 1963). The multidisciplinary effort needed to investigate lake properties led Birge and Juday to involve chemists, physicists, geologists, and other biologists in their research, and they interacted with other scientists in the developing field of limnology around the world. Initially, their work focused on individual lakes in southern Wisconsin. Later, they expanded their efforts at the Trout Lake Limnological Station in northern Wisconsin to compare and evaluate controlling features across a wide range of lake types. Their assessments of the interactions among physical, chemical, and biological processes in lakes helped to develop limnology as an ecosystem science. Substantial portions of the data Birge and Juday collected during their later years never were published, and these archived data remain a useful source of information for present-day limnologists. Edward A. Birge obtained A.B. and A.M. degrees from Williams College in Massachusetts and a Ph.D. from Harvard. He began his career at the University of Wisconsin in 1875 and remained there for the rest of his life. During his career, he assumed a variety of administrative positions, including president of the university. He also directed the Wisconsin Geological and Natural History Survey, through which he fostered the collection of extensive limnological data. Despite his administrative responsibilities, he maintained his interest in aquatic research, continuing to work at the Trout Lake Station even at the age of 85. Robert Pennak, who completed his graduate work at Wisconsin and now is emeritus professor at the University of Colorado, relates a story of how Birge admonished him, after a Model A car they were using had been turned on its side by slippery road conditions," … dammit Pennak, put it back on its wheels, the survey must go on!" (Beckel, 1987). Chancey Juday arrived at Wisconsin in 1900 as a biologist for the Geological and Natural History Survey. He received A.B. and A.M. degrees from Indiana

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology University, where he was introduced to aquatic studies during a summer research program, and he was hired to work with Birge at a time when administrative duties were limiting Birge's research efforts. Juday continued at the Geological Survey during his career and served on the faculty of the University of Wisconsin and as director of the Trout Lake Limnological Station. He supervised the graduate training of 13 Ph.D.s, several of whom have made substantial contributions to limnology. Juday was instrumental in establishing the American Society of Limnology and Oceanography and was its first president. One of Juday's last Ph.D. students, Arthur D. Hasler, was hired by the University of Wisconsin to continue limnological activities. Hasler himself became a major figure in limnology, contributing substantially to the development of limnology as an experimental science (in contrast to its origins as an observational science). During his career at the University of Wisconsin (1940–1975), Hasler supervised the training of numerous M.S. and Ph.D. limnologists, including several who have attained international status in limnology and ecology. been broadened and refined as twentieth century science has become more sophisticated (see the background paper "Organizing Paradigms for the Study of Inland Aquatic Ecosystems" at the end of this report). Today, limnological studies focus on lakes as "mirror images of the landscape around them" (A.D. Hasler, quoted in Beckel, 1987)—in other words, as open systems that receive inputs of water, solar energy, and chemical substances from terrestrial and atmospheric sources. Limnology began to take its place as a recognized field for research and scholarly activities near the turn of the century. The first limnological research institute in Germany was founded at Plön in 1891; it still is one of the major centers for limnological research (Overbeck, 1989). Edward Birge and his colleague Chancey Juday (see Box 2-3), usually regarded as the founders of academic limnology in North America, began their limnological studies at about the same time. Both spent their careers at the University of Wisconsin in Madison, and they began a rich limnological tradition that continues at that university to the present (Mortimer, 1956; Frey, 1963; Beckel, 1987; Kitchell, 1992). Birge was a zoologist and was attracted to lake studies during his student days in the 1870s in the context of the life cycles of microscopic animals (zooplankton). Juday also was trained as a biologist and was hired by Birge in 1897 to help conduct lake surveys. Birge and Juday soon branched into the physics and chemistry of lakes as they realized that the dynamics of plankton could not be understood without knowledge of these subjects. Their studies on temperature stratification and dissolved gases provided limnologists with information needed to understand virtually all biological cycles in lakes. Birge and Juday sought collaboration with physicists and chemists to study

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology lake phenomena beyond their own field of expertise. Together, these scientists developed many new techniques to measure physical properties and processes and many chemical characteristics of lakes. REGIONAL AND DESCRIPTIVE ERA Limnology continued to develop as a field of study and expand its geographic base during the first half of the twentieth century. Limnologists of the 1920s and 1930s founded many field stations, used them to collect a wealth of information on individual lakes, and synthesized this information at the regional scale. As practiced during these decades, limnology was essentially an observational science: knowledge gained was largely from sample collection and analysis of the resulting data rather than from Edward Birge and Chancey Juday with plankton trap on Lake Mendota in Madison, Wisconsin, circa 1917. SOURCE: State Historical Society of Wisconsin, Visual and Sound Archives.

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology controlled experiments. This regional/descriptive approach reflected the pervading notion of lakes as microcosms in that studies on individual lakes usually were multidisciplinary: physical, chemical, and biological measurements were included in most studies, reflecting at least implicitly the idea that lakes are complex organized systems. Efforts at the regional scale during this period also focused on classifying lakes into major types based on a multidimensional set of descriptors. For example, the scheme that classifies lakes according to trophic state (meaning general nutritional status) was developed by August Thienemann and Einar Naumann (see Box 2-4) in the 1920s. According to this scheme, an array of indicators—including a physical measure (transparency), chemical concentrations (of nutrients), and biological characteristics (species types and abundance and primary production)—was used to classify lakes according to their overall nutritional status and productivity. These and other classification efforts provided an impetus for integration and synthesis, leading to generalizations about lakes as ecosystems. In 1922, the international limnology society, Societas Internationalis Limnologiae (SIL), known in English as the International Association for Theoretical and Applied Limnology, was founded in Germany under the aegis of Thienemann and Naumann. Limnologists in the United States were organized as the Committee on Aquaculture in 1925 and as the Limnological Society of America in 1936. From a starting base of 221 members in 1936, the American society grew to include 4,000 scientists today. It joined with oceanographers to become the American Society of Limnology and Oceanography in 1948; its journal, Limnology and Oceanography, one of the premier research periodicals on lake limnology in the world, was launched in 1955. MIDCENTURY EXPANSION Most major universities in North America and Europe had hired limnology professors by the middle of the twentieth century. In almost all cases, these faculty were in departments of biological science (including zoology and botany as well as biology), and the field developed a distinct biological focus. With few exceptions, limnology programs in universities were staffed by one faculty member, and the success of the program rose or fell with the intellectual ability and initiative of that individual. In contrast, natural sciences that are related more directly to resource utilization and economic production (such as forestry, soil science, and fisheries and wildlife) typically developed academic programs with larger and more diverse faculties. Thus, their long-term success was less dependent on that of a single individual. G. Evelyn Hutchinson, who spent most of his career at Yale University, was a dominant figure in North American limnology during the middle

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology BOX 2-4 AUGUST THIENEMANN (1882–1960) AND EINAR NAUMANN (1891–1934) August Thienemann dominated the development of comparative limnology in Europe for much of the first half of this century. With strong zoological interests, Thienemann conducted detailed analyses of numerous lakes of different geomorphological, chemical, and biotic characteristics. By induction from these analyses, he synthesized common functional relationships in lake typology that were essential to the young discipline and stimulated extensive further studies throughout the world. Born in 1882 in Thüringen, Germany, Thienemann began his studies in 1901, primarily in botany and later in zoology and philosophy, at the Universities of Greifswald, Innsbruck, and Heidelberg. He initiated extensive research programs while holding positions in zoology at the Universities of Greifswald and Münster. Between 1910 and 1914, he conducted studies on the volcanic Eifel Maar lakes, which provided the basis for his organization of lakes in terms of bottom-dwelling invertebrate communities and their relationships to chemical conditions, in particular the oxygen content, of bottom waters of lakes. In 1917, Thienemann, then associate professor of hydrobiology at the University of Kiel, became director of the Hydrobiologische Anstalt der Kaiser-Wilhelm-Gesellschaft in Plön, which up to that time had been operated as a private biological station since its founding by another pioneering limnologist, Otto Zacharias, in 1891. Under Thienemann's leadership, the hydrobiological station became one of the foremost limnological research and advanced educational institutions of Europe. That foundation of limnological excellence has continued to the present as the Max-Planck-Institut für Limnologie—among the leading experimental limnological research facilities of the world. Thienemann conducted pioneering studies in many places and on many topics. For example, he led limnological expeditions to remote tropical areas such as Java. He developed ecosystem concepts in the 1920s that influenced subsequent conceptual developments by Hutchinson and Lindeman (see Boxes 2-5 and 2-6). A tireless student of limnology, he authored nearly 500 publications and 25 books. Thienemann collaborated in the early 1920s on lake typology and regional limnology with the Swedish limnologist Einar Naumann, who was an assistant professor of botany and later the first professor of limnology at the University of Lund, Sweden. Naumann's research on phytoplankton distribution and sediment formation in relation to nutrient conditions in lakes complemented the zoological interests of Thienemann. Despite highly disparate viewpoints, the two men developed a general system of classifying lakes that persists to this day. In 1921, Naumann and Thienemann founded the International Association of Theoretical and Applied Limnology (Societas Internationalis Limnologiae), drafted its statutes, and organized the first international congress of limnology in 1922. Their leadership guided this organization during its early development; it subsequently has evolved into a global association that provides its more than 3,000 members in 80 countries opportunities to exchange limnological information.

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology third of the century and a leader in the development of ecology in general (see Box 2-5). A man of wide-ranging interests and enormous intellect and insight, he brought a theoretical approach to aquatic ecology to complement its empirical underpinnings (Lewis et al., 1995). He attracted outstanding students to his program, many of whom developed prominent academic programs and had influential careers of their own. Some of Hutchinson's students eventually developed entirely new subdisciplines within ecology (see Box 2-6). BOX 2-5 G. EVELYN HUTCHINSON (1903–1991) In 1979, G. Evelyn Hutchinson joined the eminent select, such as Einstein, Edison, and Max Planck, by being awarded the Franklin Medal "for developing the scientific basis of ecology." The most voluminous scientific contributions of Hutchinson were in the biogeochemistry of lake ecosystems and included a monumental treatise on limnology (in four volumes) that demonstrated his remarkable abilities to interpret and synthesize disparate information into meaningful concepts. These scientific foundations in biogeochemistry (and population dynamics) led to major contributions in evolutionary ecology. His development of the ecological concept of multidimensional niches is a most fundamental scientific contribution. Several of his former students have led the subsequent development of ecology as a discipline. He was generous in sharing his conceptual advances with colleagues, such as in his work with Raymond Lindeman on trophic food web relationships (see Box 2-6). Hutchinson's propensity for natural history was nurtured in Cambridge, England, in a stimulating intellectual environment. After undergraduate studies at Cambridge University and brief research positions at the Stazione Zoologica in Naples and the University of Witwatersrand in South Africa, Hutchinson accepted an instructorship in zoology at Yale University in 1928. He spent the remainder of his career at Yale, continuing years of high productivity after his official retirement in 1971. In addition to teaching in natural history, ecology, limnology, and biogeochemistry, he developed a research program of enormous breadth. He made seminal contributions to knowledge of processes in lake bottom waters and sediments, oxygen deficits, benthic invertebrates, paleolimnology, and biogeochemical cycling, especially of phosphorus. He was a pioneer in the development of innovative experimental techniques, using radioisotopes of phosphorus in lakes as early as the 1940s and bioassays of nutrient effects on phytoplankton population dynamics as early as 1941. Hutchinson had penetrating understanding of many fields of science. He contributed significantly to geochemistry, oceanography, anthropology, paleontology, sociology, and behavioral sciences, as well as to his primary research areas in biogeochemistry and limnology. He received numerous national and international awards in science, and as the foremost ecologist and limnologist of the twentieth century, he left a substantial legacy in his scientific writings and the students he trained.

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology BOX 2-6 RAYMOND L. LINDEMAN (1915–1942) AND H. T. ODUM (1924–): EXAMPLES OF THE INTELLECTUAL LEGACY OF G. E. HUTCHINSON Raymond Lindeman was a young aquatic ecologist who developed an important concept for synthesizing ecological principles based on energy flow through food chains. His trophic-dynamic concept, published posthumously in 1942, emphasized the importance of short-term nutritional functioning to an understanding of long-term changes in the dynamics of lake communities. Drawing from conceptual works of the plant ecologist Tansley and the limnologists Thienemann and Hutchinson, Lindeman showed how organic and inorganic cycles of nutrients are integrated. His theoretical model of nutrient cycling, expressed in terms of energy flow, allowed evaluations of biological and ecological efficiencies of energy transfer over long periods. Lindeman did his graduate studies in zoology at the University of Minnesota under Samuel Eddy and W. S. Cooper. His doctoral research involved a detailed evaluation of trophic (food web) structure in Cedar Bog Lake and provided support for the general tenets of trophic-dynamic concepts. In 1941, Lindeman began postdoctoral studies at Yale University with G. E. Hutchinson. Many of Lindeman's trophic-dynamic ideas were melded into conceptual and mathematical treatments from Hutchinson's then-unpublished writings. The combined efforts of these two scientists led to many major conceptual breakthroughs. Hutchinson also assisted with the publication of Lindeman's synthesis paper (Lindeman, 1942), which was rejected at first because of its theoretical nature. Trophic dynamics and ecosystem concepts are so embedded in modern ecology that it is difficult to comprehend how revolutionary his theoretical model was at the time. The paper provided much of the intellectual framework on which subsequent development of ecosystem ecology was based. Lindeman died prematurely in 1942 at age 27. Howard Thomas Odum, known as H. T. or Tom, is a major figure of modern aquatic ecology whose influence extends beyond the confines of traditional ecology. His innovations spurred the development of several new disciplines—in particular, systems ecology, ecological economics, and ecological engineering—that relate ecology to other sciences in analyzing major environmental problems. Odum was born in Durham, North Carolina, the son of Howard W. Odum, a renowned sociologist at the University of North Carolina. He received an A.B. in zoology in 1947 from that institution and a Ph.D. in 1951 under G. E. Hutchinson at Yale University. His career was spent at several academic institutions, including the University of Florida, where he is now professor emeritus. His work on the energetics of Silver Springs, Florida (Odum, 1957), is a landmark whose impact on flowing water ecosystems is analogous to the impacts of Lindeman's trophic-dynamic work on lakes. He advanced experimental ecology through work on mesocosms and by refining the diurnal oxygen method for measuring primary production. He directed several large-scale experiments in a tropical rain forest in Puerto Rico (Odum and Pigeon, 1970) that were classic examples in forest ecology and the assessment of how radionuclides

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology ecosystems. Chapter 3 describes many of these advances in more detail and explains the roles of limnologists, along with aquatic scientists in related discipline, in assessing and developing solutions for contemporary problems related to the degradation of inland waters. Many advances in limnology were made by academic limnologists and other scientists working in departments not traditionally focusing on limnology (such as civil and environmental engineering, environmental science, and earth sciences); others were made by interdisciplinary research teams associated with government agencies and with contract research and consulting firms. Thus, limnological research has spread beyond its traditional base of operations in academic departments of biological science. Activity in limnology in recent decades is reflected by the vitality of its professional societies and scholarly journals. Within the past 15 years, three new North American societies have formed, each resulting from the expanding activities in a particular aspect of limnology and its related aquatic sciences: The North American Benthological Society (NABS) expanded from an older regional organization (the Midwest Benthological Society) in 1974, emphasizing stream ecology and processes occurring at the interface between water and land. The North American Lake Management Society (NALMS) was established in 1980 as an outgrowth of expanding interest in restoring and rehabilitating lakes and reservoirs degraded by human activity. The Society of Wetland Scientists (SWS) was founded in 1980 to promote research for understanding and managing wetlands. Memberships in the above three societies plus the two older limnological societies, the American Society of Limnology and Oceanography (ASLO) and the International Association for Great Lakes Research (IAGLR), total more than 12,000 (see Appendix B). Many limnologists also belong to SIL and to discipline-based societies. The aquatic section of the Ecological Society of America, for example, has more than 1,000 members (although many of these individuals also belong to one or more of the five primary limnological societies listed above). The scholarly and technical journals published by the limnological societies continue to grow in circulation and pages published annually (see Table 2-2), and several new journals that focus on different aspects of limnology (for example, Lake and Reservoir Management, Ecological Engineering, and Wetlands) have appeared within the past two decades. Moreover, annual meetings of the societies attract growing numbers of presentations and attendees. For example, the number of presentations at the annual meeting of NABS increased from 234 to 409 between 1984 and 1994, while the number of papers at the annual SWS meeting increased

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology TABLE 2-2 Recent Publication Trends for Limnological Journals     Journala   Year L&O CJFAS JGLR JNABSb LRMc W Circulation 1984 5,215 2,000 na 943 na 460   1989 4,763 1,900 na 1,179 na 1,930   1994 5,171 1,675 na 1,441 na 3,848 Pages published 1984 1,358 1,862 466 325 390 220   1989 1,766 2,437 728 375 242 327   1994 2,025 3,187 800 617 352 320d Publication frequency (issues per year) 1984 6 12 4 4 1 1   1989 8 13 4 4 2 3   1994 8 13 4 4 3 4 Number of papers submitted 1984 na 416 na 65 na 19   1989 na 421 na 73 na 37   1994 316e 474 na 96 na 80 NOTE: na = information unavailable. a Journal abbreviation and responsible society: L&O: Limnology and Oceanography, American Society of Limnology and Oceanography; CJFAS: Canadian Journal of Fisheries and Aquatic Science, National Research Council of Canada; JGLR: Journal of Great Lakes Research, International Association for Great Lakes Research; JNABS: Journal of the North American Benthological Society, North American Benthological Society; LRM: Lake and Reservoir Management, North American Lake Management Society; W: Wetlands, Society of Wetland Scientists. b First set of numbers for this journal represents 1986, the journal's first year of publication. c First set of numbers for this journal represents 1985, the journal's first year of publication. d Page size increased by approximately 70 percent. e This number is for 1993; no earlier statistics are available. from 51 to 306. It is apparent from this growth in presentations and publications that activity in limnology is continuing to increase. Limnology courses continue to be offered at most major research universities. For example, 59 of 69 universities surveyed for this report indicated that they offer an introductory limnology course for undergraduates (see Appendix A). Furthermore, introductory limnology courses at major universities generally have stable or increasing enrollments; 55 of 57 universities responding to a survey question about student interest in limnology reported that interest is increasing or holding steady (see Appendix A). Graduate training in limnology is available at many of these institutions, even though only a few universities have distinct degrees or programs called limnology. In addition, during the past decade or so an increasing number of colleges and non-Ph.D.-granting universities (such as the University of Wisconsin, Stevens Point, described in Chapter 4) have developed M.S.-level programs related to limnology or aquatic science. Several new textbooks on stream and wetland limnology have been published, as have new editions of popular limnology books that focus on

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology lakes (e.g., Mitsch and Gosselink, 1993; Horne and Goldman, 1994; Allan, 1995). However, not all is well in limnology. Indeed, some of the positive characteristics of limnology at the close of the twentieth century can also be interpreted as indicators of underlying problems. For example, the formation of new societies is symptomatic of increased fragmentation, as well as an unwillingness on the part of the original society (ASLO) to embrace fully some of the newer aspects of the field, in particular applied limnology, resource management-oriented activities, and wetland ecology. In general, problems in the conduct of modern limnology can be grouped into six major areas: inadequacy or instability of research support, especially in certain areas (such as physical and chemical limnology and wetland ecology); loss of some prominent academic positions, especially in biological limnology; growing fragmentation in academic programs (an ironic situation for an inherently interdisciplinary field); inadequate educational programs, both at the general education level and at the professional level; growing professional separation among various kinds of limnologists; and poor public understanding of limnology and failure to identify it as a field that can contribute to the solution of aquatic problems important to human society. Limnologists have not been reluctant to express concerns about the viability of their field. Discussions on these issues have appeared in limnological journals over the past decade, most notably in Limnology and Oceanography (e.g., Jumars, 1990; Kalff, 1991; Wetzel, 1991). These discussions have led to several studies dedicated to critical self-examination and to the development of recommendations to overcome perceived deficiencies and problems. Major self-analyses include (1) the Freshwater Imperative (Naiman et al., 1995), a broad initiative of a diverse group of aquatic scientists to address research needs in limnology, develop plans for government-supported interdisciplinary research programs on freshwater ecosystems, and otherwise promote the professional development of the field; and (2) ASLO's self-assessment of the field (Lewis et al., 1995), which contains a broad range of recommendations to reinvigorate the field and reverse the trend toward fragmentation among its component disciplines and subject areas. As discussed in this chapter, much of the recent research support for limnology has been tied to targeted research programs in mission-oriented agencies focused on practical pollution problems. Although there is much to be gained from the focus that such programs provide, their funding

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology levels rise and decline over a relatively small number of years as public and congressional interest waxes and wanes or as scientists develop solutions to problems. This approach simply is not adequate to support the basic scientific research and consistent training of new generations of scientists needed if limnology is to play a role in supporting wise and sustainable management of inland aquatic ecosystems. Some contend that the lack of a central federal program for limnology has led to a lack of research funding opportunities in limnology and has contributed to a decline of this field in academia (Jumars, 1990). Others disagree with this pessimistic attitude and point to the many advances in understanding and practical accomplishments achieved by limnologists in recent decades. To a certain extent, these diverging opinions reflect basic philosophical differences (is the ''limnological cup" half full or half empty?) that can never be resolved completely. Nonetheless, it is likely that few regard current mechanisms for funding limnological research as optimal. Within the National Science Foundation (NSF), there is no program that deals specifically with limnology in its broad definition. Instead, support for limnological research is subsumed in a variety of programs, including NSF's Divisions of Atmospheric Sciences, Earth Sciences, Environmental Biology, Integrative Biology and Neuroscience, International Programs, Ocean Sciences, and Polar Programs (Firth and Wyngaard, 1993). In contrast, NSF has a specific division (Ocean Sciences) devoted to the study of oceanography, which is bolstered by a similar funding program administered by the Office of Naval Research (Jumars, 1990). Most of the support for limnological research in NSF comes from the Division of Environmental Biology. As a result, support for research in chemical and physical limnology is not emphasized, and opportunities for support of interdisciplinary and long-term research have been limited. For example, 90 percent of NSF's grants on subjects directly or indirectly related to limnology in 1991 included work with a biological component, but only 25 percent supported studies with a chemical component and only 2 percent supported studies with a physical focus (Firth and Wyngaard, 1993). One encouraging sign of change to promote interdisciplinary research on aquatic ecosystems within NSF is its new "Water and Watersheds" initiative. A joint effort between the NSF and the Environmental Protection Agency (EPA), this program targeted $10 million in competitively awarded funds in fiscal year 1995 to university-based aquatic research. In terms of generating proposals, the first competition announced in February 1995 was overwhelmingly successful: more than 650 proposals were submitted for review. Financial limitations meant that only about 30 proposals (roughly 5 percent) received funding. Nonetheless, the large response to the call for proposals suggests that the program addresses a major, unmet research need. The Water and Watersheds research initiative

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology was funded primarily by the EPA (roughly 70 percent) in 1995, and the program does not yet have a permanent home in the NSF administrative structure. Consequently, it is premature to conclude that this program will provide a long-term source of funds for interdisciplinary research in limnology, but developing a permanent program to fund such research should be a priority. Over the past decade or two, limnological programs have been eliminated or significantly downsized at some leading research universities as prominent faculty limnologists retired. Notable examples include G. E. Hutchinson of Yale University (Box 2-5); D. G. Frey of Indiana University, highly regarded for his examination of biological remains in sediments to chronicle past histories of lake conditions; and W. T. Edmondson of the University of Washington, noted for his pioneering studies of eutrophication in Lake Washington (see Chapter 4). Although Frey retired and was not replaced, Indiana University still offers a limnology course through its Department of Public and Environmental Affairs, but Yale no longer offers courses or employs faculty in limnology. The University of Washington offered a course in limnology for more than 30 years through the Department of Zoology, but when Edmondson's retirement was followed by cuts in state funding, the frequency of the course was reduced, and it was taught by visiting professors for several years (in 1996, the university again hired a limnologist to serve on its faculty). On a national basis, it is fair to say that some faculty positions have been lost because of declining financial resources in some universities, but in other cases, positions vacated by limnologists have been converted to other subject areas, usually some aspect of subcellular biology, which reflects a trend in many academic biology programs away from organismal and higher-level biology and toward subcellular and molecular scales. The loss of highly visible academic positions in biological limnology probably is the single most important factor contributing to the perception among academic limnologists that all is not well within their profession, but in some respects the concern about lost positions may not be well founded. As limnological positions have been los tin traditional biology departments, others have been added in departments and colleges of environmental science and engineering, fisheries science, natural resources, and other resource-oriented programs. It is possible that larger numbers of faculty are involved in teaching and research across the broad field of limnology at research universities in the 1990s than ever before. However, they are dispersed more widely across departments and colleges than they were in earlier decades, when limnology was a narrower and simpler field that focused on temperate lakes. In summary, the elimination or deemphasis of limnology in the biology departments of major research universities has left a leadership vacuum in limnology, at least at many institutions, as well as a vacuum in the training of biologists

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology with skills in basic systematics and the organismal biology of aquatic ecosystems. Overall, the dispersion of limnology into so many different academic programs in universities has led to severe fragmentation of the field. Few universities are producing limnologists with truly interdisciplinary backgrounds, an ecosystem perspective, and an ability to integrate across the sciences and major categories of aquatic ecosystems. In addition, most universities do not provide adequate course offerings in limnology at the general education level. The fragmentation of limnologists during their education continues at the professional level. There is no limnological society or organization that represents the field and its practitioners as a whole. Although most, if not all, of the traditional journals publish occasional articles on streams and wetlands, their focus generally is on lake science. There is no journal that covers both the fundamental and applied aspects of limnology and all major categories of water bodies within the domain of limnology. Lake, stream, and wetland limnologists and fisheries scientists largely go their separate ways when joining professional societies, attending conferences, and publishing scientific papers. Although the Ecological Society of America includes theoretical and applied ecologists in its membership and has a special applied ecology section, fundamental and more practical, management-oriented aspects of limnological science are covered by separate societies (ASLO and NALMS). Both aspects of limnology have much to gain from closer interactions. Limnologists involved in research on the Great Lakes also have their own society and journal, a situation that is particularly ironic given that ASLO combines limnologists and oceanographers. As noted earlier, Great Lakes research combines elements of both limnology and oceanography (the latter particularly in terms of the scale of research vessels and equipment needed to conduct the research). The American Fisheries Society combines interests in fundamental science (fish physiology and genetics) with fisheries management, and it formulates and publicizes positions on the application of science to resource management issues. Nonetheless, fisheries science is not well integrated into limnology at the professional level (or for that matter in academic programs), in spite of the fact that fish are obviously integral components of aquatic food webs. Although limnology is a diverse field, it is no more so than many other fields that have managed to bring their varied elements under the umbrella of one professional society that provides a sense of identity and public visibility to the field. Civil engineering, for example, sometimes is referred to as a "holding company" rather than a discipline because of the breadth and diversity of activities in which civil engineers are engaged. Nonetheless, one society, the American Society of Civil Engineers, represents the entire field. Similar situations prevail in chemistry, where the American Chemical Society includes theoretical and applied chemists working in

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology fields as diverse as quantum mechanics and polymer science, and in microbiology, where the American Society for Microbiology publishes six subdisciplinary journals dealing with a broad range of fundamental and applied studies. The fragmentation of limnology at the educational and professional levels has left the field with an identity crisis. Limnology is poorly understood by scientists and the general public. Even many aquatic scientists do not realize their ties to the general field of limnology or (in some cases) their effective involvement in limnological research. This problem of visibility tends to relegate limnologists and their science to secondary positions in public policy debates and decisions about aquatic resource management—situations in which their expertise is highly relevant. Root causes of the problems described in preceding paragraphs are numerous and include factors that are internal to the field of limnology and external factors over which limnologists have had little control. Professional fragmentation—exemplified by the lack of a single society and single journal that represents all major areas of the field—would seem to be a problem of limnologists' own making. In part, it reflects an unwillingness by the older limnological societies and journals to diversify themselves and fully embrace some of the newer trends, such as the emphasis on restoration- and management-oriented activities that spawned the formation of organizations such as NALMS and SWS. Clearly, limnologists have it within their own power to overcome this professional fragmentation, and indeed only they can do so. Causes of educational fragmentation are complicated and more difficult to assign. In large part, they reflect the long developmental history of academic disciplines and department structures within universities that have been defined for many decades by a primary orientation toward the basic science disciplines. Limnology, defined by the objects it studies (inland aquatic ecosystems), is inherently multidisciplinary and interdisciplinary, and components of the field have developed in many departments. The problems of academic limnology are a mirror of the problems of water science as a whole in higher education: water science is an interest within many fields, but it is not the primary focus of any of the traditional departments or disciplines. Moreover, "turf" problems inhibit any existing department from assuming too strong a leadership role over the entire field. At the same time, there probably is little enthusiasm among university administrators (deans and department heads) in this time of declining financial resources for reorganizations that would remove limnologically oriented faculty from existing programs and place them in new administrative units. It is interesting to note that the fragmentation typically found in water resource science and limnological programs in academic institutions does not hold for natural resource subjects that traditionally have been linked

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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology directly to production-oriented economic activities. For example, soil science is an inherently multidisciplinary and interdisciplinary subject, but it has achieved departmental status in many land-grant universities. A similar situation exists in the field of forestry. No one considers it unusual or improper to have microbiologists, chemists, and physicists in the same department of soil science; it should not be so difficult to convince university faculty and administrators that broad-based departments or schools of aquatic science are both feasible and desirable. Other recent critical examinations of limnology have dealt with the broad array of deficiencies and problems that face the field (e.g., Lewis et al., 1995) and with the development of a research prospectus and recommendations for better funding support (e.g., Naiman et al., 1995). Consequently, this report focuses on educational issues in limnology. In this context, the committee that wrote the report examined both the training of professional limnologists at all levels (B.S. to Ph.D.) and the provision of limnological information in the general education of college students and the public. Although the major emphasis of this report is education, the problems of limnology cannot be solved in academia alone. Also needed are improved links between those who conduct research in limnology and those who manage water resources. The professional societies in limnology have a critical role to play in helping to develop these links and in serving as advocates for the discipline of limnology as a whole. REFERENCES Allan, J. D. 1995. Stream Ecology: Structure and Function of Running Waters. New York: Chapman Hall. Beckel, A. L. 1987. Breaking New Waters. Transactions of the Wisconsin Academy of Sciences, Arts, and Letters, special issue. Madison, Wisc.: Wisconsin Academy of Sciences, Arts, and Letters. Bradbury, J. P., and R. O. Megard. 1972. Stratigraphic record of pollution in Shagawa lake, northeastern Minnesota. Geol. Soc. Am. Bull. 83:2639–2648. Bradbury, J. P., and J. C. B. Waddington. 1973. The impact of European settlement on Shagawa Lake, northeastern Minnesota. Pp. 289–307 in Quaternary Plant Ecology, H. J. B. Birks and R. G. West, eds. Oxford, England: Blackwell. Brezonik, P. L., J. G. Eaton, T. M. Frost, P. J. Garrison, T. K. Kratz, C. E. Mach, J. H. McCormick, J. A. Perry, W. A. Rose, C. J. Sampson, B. C. L. Shelley, W. A. Swenson, and K. E. Webster. 1993. Experimental acidification of Little Rock Lake, Wisconsin: Chemical and biological changes over the pH range 6.1 to 4.7. Can. J. Fish. Aquat. Sci. 50:1101–1121. Cairns, J., Jr., B. R. Niederlehner, and D. R. Orvos, eds. 1992. Predicting Ecosystem Risk. Princeton, N.J.: Princeton Scientific Publishing. Carpenter, S. R., T. M. Frost, D. Heisey, and T. K. Kratz. 1989. Randomized intervention analysis and the interpretation of whole-ecosystem experiments. Ecology 70:1142–1152. Charles, D. F., R. W. Battarbee, I. Renberg, H. Van Dam, and J. P. Smol. 1989. Paleoecological

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