Edmondson, Wallis Thomas

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(b. Milwaukee, Wisconsin, 24 April 1916;

d. Seattle, Washington, 10 January 2000), ecology, limnology, oceanography, environmental science.

An American ecologist and limnologist, Edmondson was famous for his pioneering work on the effects of nutrient pollution upon freshwater environments. In collaboration with his wife, Yvette Hardman Edmondson, he developed a quantitative method connecting ratios between eggs and females in zooplankton to calculate population and birth rates. His research formed the foundation for the basic study of polluted aquatic environments, while informing political and technological solutions for their recovery. In tracing how nutrient loading, the excessive concentration of phosphorous and nitrogen, boosted the rapid growth of blue-green algae, which stripped water of oxygen and often killed all other life, Edmondson demonstrated how human alterations to aquatic ecosystems had negative but ultimately reversible effects.

Childhood and Education . Edmondson, known to friends and colleagues by his nickname, “Tommy,” came to his calling early. As a young boy, he spent many hours collecting microscopic flora and fauna from the lakes, ponds, and vernal pools dotting the glaciated hills of Wisconsin. His parents gave him his first microscope at the age of twelve and a copy of Henry Baldwin Ward and George Chandler Whipple’s classic text, Freshwater Biology, as a birthday present the following year. As an eighteen-year-old in New Haven, Connecticut, where he had moved with his widowed mother, Edmondson befriended Yale zoologist and ecologist, G. Evelyn Hutchinson, while still a student at Hillhouse High School. The precocious boy impressed the eminent scholar, who gave Edmondson access to his collection of rotifers from India, Hispaniola, and across North America at Yale’s Osborn Memorial Laboratories. Edmondson enrolled at Yale in 1934, and by the time he graduated had already published eight articles, including one in Science. His first publications, based upon Hutchinson’s collection, focused on systematics, fixation methods, and substrate effects derived from his work on one of his future specialties, the phylum Rotifera, one of the most abundant and prominent types of zoo-plankton. By focusing on R otifera, Edmondson grounded his future career firmly in the tradition of population ecology established by his mentor, Hutchinson.

After graduation, Edmondson received a research assistantship in 1938 to attend the University of Wisconsin, where he worked with the noted limnologists Chauncey Juday and Edward A. Birge at their famed Trout Lake site. At Madison, Edmondson studied the chemical ecology of sessile rotifers, correlating the separate effects of pH, alkalinity, and ionic strength upon their reproduction and movement. Juday and Birge pushed the young scientist to hone his aptitude for observational fieldwork as carefully has he had perfected his experimental laboratory skills. While in Wisconsin, Edmondson also met his future wife, Yvette Hardman, then a doctoral candidate in microbial ecology, who later became his lifelong collaborator. Returning to Yale in 1939, he pursued his PhD under the direction of his old mentor, Hutchinson, and in 1941 defended his thesis on the population dynamics and ecology of sessile rotifers. In his doctoral research he had discovered that survival rates for rotifers increased if they lived in colonies instead of as individuals. Several hours after his thesis defense, he married Hard-man, who had also completed her PhD at Wisconsin, in Yale’s Dwight Chapel. Although Edmondson saw himself as part of the great Hutchinson lineage, his time at Wisconsin spent outdoors, on the water, would later prove to be as valuable as his training at Yale in hypothesis testing and mathematical modeling.

Edmondson’s Egg Ratio Method . Before Edmondson embarked on his academic career, he joined the war effort against the Axis, working as a physical oceanographer for the U.S. Navy. His wartime duties took him first to the American Museum of Natural History, then the Woods Hole Oceanographic Institution, where he collaborated with Walter Munk, Henry Stommel, George Clarke, and Maurice Ewing on predicting wave heights to aid amphibious assaults and using sound refraction to detect downed aircraft and submersibles. (Yvette, at this time, was teaching biology at Bennington College, her alma mater.) After the war, Edmondson stayed briefly at Woods Hole before moving to Harvard University in 1946. There, reunited with Yvette, he began research on the effects of nutrient fertilization on primary production, the fundamental ecological process whereby organic compounds are created from inorganic compounds, usually by plants using photosynthesis. Secondary production, in contrast, is the process whereby other creatures take primary producers and consume them as food or nutrients, as a cow, might consume grass. This work eventually became the cornerstone of his professional reputation.

In 1949, the Edmondsons moved west, where he accepted a permanent faculty position at the University of Washington. He remained in Seattle for the rest of his career. The institution was a good match; under the leadership of Trevor Kincaid at the beginning of the twentieth century, Washington had already established a strong reputation in zoology and botany. During the Cold War decades, the university grew rapidly thanks to a vibrant local economy and aggressive efforts by its leaders to boost federal and private funding. Backed by numerous grants and fellowships, including several from the new National Science Foundation, created in 1950, Edmondson helped to make Washington’s zoology and oceanography programs internationally famous. Together with Yvette and his growing group of graduate students, Edmondson pursued his work on the effect of nutrient enrichment on primary production. At the time, calculating biological productivity as a combined property of aquatic ecosystems was an innovative program, embraced by only a few oceanographers and limnoecologists like Edmondson. His research path blended his experiences at Yale and Wisconsin to produce one of the most important analytical concepts in freshwater ecology: the egg ratio method.

Publishing his findings initially in 1960 after a sabbatical at Istituto Italiano di Idrobiologia in Pallanza, Italy, Edmondson stated that the ratios between eggs and females in zooplankton, like rotifers, yielded quantitative estimates of birth rates. Suddenly, previously intractable problems became solvable, from complex relationships between primary production and secondary production to predator-prey interactions and their effects upon community structure. The egg-ratio method gave ecologists a powerful quantitative tool. Now, they could measure planktonic population dynamics historically, often in the field, without disturbing natural populations or resorting to inaccurate estimates. Before, scientists looked at aquatic ecosystems as something akin to a black box; now they began to raise further questions about species composition, community formation, and evolutionary dynamics as observed through ecological processes.

The Lake Washington Story . The Pacific Northwest was a near-perfect setting for Edmondson’s research, with its mosaic of deep saltwater inlets and abundant lakes. Edmondson had learned that atypical lakes provided the best research opportunities, so he and his students scoured the region, looking for suitable locations. On the Columbia Plateau of eastern Washington, they found Soap Lake and Lake Lenore, high in salinity and home to unique biota. In the Puget Sound lowlands north of Seattle, Hall Lake, a glacial kettle, was a textbook example of biogenic meromixis, or the limited mixing of water due to heavy accumulations of sediment or decayed bacteria. Yet no place proved more fruitful for his studies than Lake Washington, located a short walk from his campus office. At first, Edmondson was uninterested in the lake. Two of his doctoral students, however, made it their laboratory, George C. Anderson focusing on phytoplankton, microscopic plants, and Gabriel W. Comita on copepods, microscopic crustaceans that fed on phytoplankton. On a June day in 1955, after a sailing trip on Lake Washington, Anderson returned to Edmondson’s laboratory with a beer bottle full of water, telling his mentor that the lake had changed. Puzzled, the two graduate students, together with Edmondson, explained what swimmers and boaters had already noticed: the dramatic increase of a noxious growth, the blue-green alga Oscillatoria rubescens.

“This, of course,” Edmondson recalled later in The Uses of Ecology: Lake Washington and Beyond, “was wildly exciting to us” (p. 13). He had found an unparalleled opportunity to test the association between primary productivity and lake organisms through time. Edmondson knew of earlier studies from Switzerland’s Lake Zürich that identified the algae species as an indicator of human-induced eutrophication—a condition whereby excess nutrients such as phosphates, abundant in untreated sewage, hastened algal growth. The fast-growing algae stripped the waters of dissolved oxygen and killed all but the hardiest animals. Since sewage effluent was an extremely effective fertilizer, nutrients liberated by dying algae could continue the cycle unabated. In subsequent experiments, Edmondson and his students found that the visibility in the lake’s previously clear waters, which once exceeded three meters in depth, had diminished to less than one meter. Even more alarming was how quickly the lake had changed; a 1939 study had found the waters clear and free of organic material. Now, during the hot summer months, the water looked like pea soup. Rafts of rotting, stinking algae clogged the lake, washing up on beaches and forcing health officials to close popular swimming spots. Alarmed, Edmondson and his students rushed to publish their findings.

As Edmondson’s research became widely known throughout the metropolitan Seattle area, local newspapers turned to him for explanation and cited his research. Soon the scientist found himself recruited in a battle to save Lake Washington. A group of concerned citizens led by James R. Ellis, a crusading young attorney, had helped to form the Metropolitan Problems Advisory Council to address the mounting problems facing Seattle and its environs, from poor transportation to inadequate pollution control. Ellis and others had long worried that unchecked sewage dumping would imperil Lake Washington; now they seemed to have scientific proof. In 1956, Ellis asked Edmondson to explain his findings to the council. The ecologist’s eight-page memo explained, in lay language, free of jargon, the grim state of Lake Washington and the possibilities for its revival. The combined effluent dumped into the lake by the ten suburban sewage treatment plants topped 20 million gallons daily. The rate of algal growth was directly proportional to the increase in sewage, and poisoning the algae or scooping it from the lake for removal would not solve the problem. Without definite and immediate action, he warned, the lake would continue to deteriorate.

Armed with Edmondson’s findings, Ellis and the Metropolitan Problems Advisory Council proposed creating a new regional governmental agency, the Municipality of Metropolitan Seattle, or Metro, to eliminate the pollution threat. Metro would eliminate the pollution threat by building massive interceptor sewer and treatement system to remove sewage from Lake Washington permanently. Edmondson was now in the middle of a bitter political struggle pitting political reformers, like Ellis, against angry suburban homeowners resistant to higher taxes and bigger government. The first Metro referendum, which went to the voters in March 1958, was defeated in the suburbs surrounding Lake Washington. As pollution increased later that summer, Metro proponents submitted a revised version that won approval in September 1958, with 58 percent of Seattle residents and 67 percent in the rest of King County voting in favor. Construction on the new sewer system began soon thereafter. During both elections, Edmondson gave numerous interviews and held debates with Metro opponents on the science behind Lake Washington’s decline. The situation in the late 1950s, he later wrote, “was an example in which the results of basic research could be put to immediate application,” and Edmondson soon earned a national reputation as a scientist who could link research to policy without simplifying the science (1991, p. 286).

After the elections, Edmondson confidently predicted that once sewage was treated and diverted away, Lake Washington would rebound and water quality would recover. By 1969, Secchi disk sampling indicated that water column transparency had increased from less than one meter six years before to more than three meters. The revival of Lake Washington became a textbook staple of how bioremediation could pull aquatic ecosystems back from the brink of collapse. Scientists and politicians in Ontario and Switzerland later turned to Edmondson’s findings to resuscitate Lake Erie and Lake Zürich. The National Research Council would later conclude that Lake Washington’s revival, guided by Edmondson’s work, helped to set the course for effective restoration of other aquatic environments around the world. Ray T. Oglesby, a Cornell University limnologist, later wrote: “The ‘Lake Washington Story’ has become to the limnologist what the Lord’s Prayer is to a preacher, a vital, uniquely clear, well-documented statement of what the profession is all about” (quoted in Lehman, 1988, p. 1237).

Accolades and Awards . Edmondson remained an active researcher with his wife, Yvette, continuing to track long-term changes in Lake Washington by studying nutrient addition, enhanced grazer abundance, and elevated alkalinity over time. Indeed, Yvette was an important figure in her own right, serving as editor of Limnology and Oceanography for nineteen years and helping to establish the journal as a leading publication in both fields. Even after their joint retirement in 1986, both continued to publish and attend conferences. Honors flowed to them, focused primarily on Edmondson’s initial studies of fertilization and productivity in Lake Washington, work made possible, in large part, because of Yvette’s laboratory assistance. Tommy Edmondson joined the National Academy of Sciences in 1973, the same year he received the academy’s Frederick Garner Cottrell Award for Environmental Quality. Other tributes among many included Ecological Society of America’s Eminent Ecologist Award, the Einar Naumann–August Thienemann Medal of the Societas Internationalis Limnologiae, and a special resolution by the Washington State legislature commemorating his contributions to public welfare and environmental protection. Edmondson died in Seattle.


The Special Collections of the University of Washington Libraries contains his complete personal papers.


With G. C. Anderson and D. R. Peterson. “Artificial Eutrophication of Lake Washington.” Limnology and Oceanography 1 (January 1956): 47–53. The first publication on the changing conditions in Lake Washington, near Seattle.

“Reproductive Rate of Rotifers in Natural Populations.”Memorie dell’Istituto Italiano di Idrobiologia 12 (1960): 21–77. The original explanation of Edmondson’s egg ratio method.

“Reproductive Rate of Planktonic Rotifers as Related to Food and Temperature in Nature.” Ecological Monographs 35 (1965): 61–111.

“The Present Condition of Lake Washington.” Verhandlungen der Internationalen Vereinigung für theoretische und angewandte Limnologie 18 (1972): 284–291.

The Uses of Ecology: Lake Washington and Beyond. Seattle: University of Washington Press, 1991. A series of essays based upon the John and Jesse Danz Lectures at the University of Washington in 1990.


“Bibliography of W. T. Edmondson,” In “W. T. Edmondson Celebratory Issue,” edited by Nelson G. Hairston Jr., John T. Lehman, and John G. Stockner. Special Issue, Limnology and Oceanography 33 (1988): 1241–1243. Complete bibliography of Edmondson’s publications and theses directed through 1988.

Hutchinson, G. E. “W. Thomas Edmondson.” In “W. T. Edmondson Celebratory Issue,” edited by Nelson G. Hairston Jr., John T. Lehman, and John G. Stockner. Special Issue, Limnology and Oceanography 33 (1988): 1231–1233.

Lehman, J. T. “Good Professor Edmondson,” In “W. T. Edmondson Celebratory Issue,” edited by Nelson G. Hairston Jr., John T. Lehman, and John G. Stockner. Special Issue, Limnology and Oceanography 33 (1988): 1234–1240.

Matthew Klingle

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