FEATURE
How our natural resources function and how their subcomponent systems interrelate had not been comprehensively and concurrently examined until recently. Although the global network of terrestrial and aquatic habitats can be considered as unique research sites, coordinated investigations regarding their status and conservaton requirements have never existed. As the pressures on and for man became more apparent, many scientists turned their attention toward the international responsibilities of food supply, the environment, populations, and man's role in these a'reas. In 1964, the International Council for Scientific Unions (ICSU) created a Special Committee for the International Biological Program (SCIBP). The committee organized a research program directed toward defining the biological basis o f productivity for human welfare and provided the opportunity for a global study designed to determine: e organic production on land, i n fresh waters, and in the seas e potentialities and uses of new as well as existing natural resources e human adaptabillty to changing conditions At the outset of the IBP ( E S & T June 1968 p 411), i t was clear that each of the 60 nations involved could and would emphaslze the research areas of principal importance to it Planning these extensive research efforts oc706
Environmental Science & Technology
Freshwater ecosystem research in water quality management
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Austria: Hinterer-Finstertaler Vorderer-Finstertaler
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James J. Ferris
Canada: Char, Clear, Great Bear
Rensselaer Polytechnic Institute Troy, N . Y . 12181
Denmark: Esrom Italy: Maggiore Japan: Biwa
Nicholas L. Clesceri
Netherlands: Tjeukemeer
Rensselaer Polytechnic Institute Troy, N . Y . 12181
Norway: Heimdalsvatn Poland: Mikolajskie
Stanley I. Auerbach
Scotland: Lock Leven
Oak Ridge National Laboratory Oak Ridge, Tenn. 37830
U.S.A.: Alaska, Idaho, N.Y., Utah, Wash., Wis. U.S.S.R.: Baikul, Karakul curred from 1964 to mid-1967, and actual research was conducted until mid-1973, a year beyond the original schedule. primarily due to synthesis activities in certain countries. The overall program itself has been extended through mid-1974, \Nith the activities of the final year being directed primarily at synthesis and transition.
Ecosystem components forming submodels in CLEAN
The U.S. IBP
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Multidisciplinary teams of U.S. scientists combined their efforts and results (via simulation modeling) toward understanding total ecosystems in the U.S. The actual participation by the U.S. commenced in 1965 when the U.S. National Committee for the IBP was appointed by the National Academy of Sciences. The lead agency for funding these integrated research programs has been the National Science Foundation. Subject areas selected for study by the Nationa Committee adhered to those suggested by SCIBP with the addition of Environmental Physiology and Systematics, and Biogeography to fully define the purposes of the IBP. Since the full complement of IBP prograi.ns in the U.S. has been discussed elsewhere, this feature will be concerned with the Environmental Management component of the U.S./I BP. The environmental management programs fit into the principles of the integrated research program since they possessed broad interdisciplinary goals and contained specific program obiectives; defined the major variables requiring monitoring in the system and the critical processes needing mathematical expression via systems models: and identified those studies through the models which permitted and necessitated parameter estimates. Also, the research in the U.S. component has been judged on its quality and contribution to ecological science; its relationship to other IBP projects; and its role in developing, testing, and furthering ecosystem models. Freshwater Productivity (PF), one of the seven subject areas in the environmental management program, has been investigated throughout the I BP, including the U.S. As with other program elements of this global project, a common goal for attaining assessment data that would eventually lead to rational resource management for freshwater ecosysteins was established. This ability for assessment was based on a simplified method, and the predictability of changes in the conditions and dynamics of ecosystems was achieved by ecosystem modeling. The study of more than 8 0 lakes and reservoirs within the framework of the IBP has afforded the aquatic science teams the first opportunity to generate widespread baseline data concerned with those factors (internal and exogenous) that influence and possibly control production in limnologic environments. I t has become apparent that for ma.ny fresh waters, insufficient or inappropriate data have prevented full predictability of ecologic conditions via ecosystem simulation. Other methodologies have also beeri used in concert with modeling tech-
Naniophytoilaikton N h PhytAplanktoi
Preditory zooplankton
Bass-like fish
/
Macrobhytes\
organic Suspended matter
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Carp-like fish
Source: R. A. Park
Volume 8 , Number 8 , August 1974
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Phytoplankton ,
Zooplankton
thophosphate
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I niques toward determining productivity in freshwater systems. They will not be discussed herein. The U.S. was integrated into biomes or major communities of living organisms, each demonstrating its own scientific similarity, and comprising large-scale multidisciplinary efforts. The biomes studied included the Coniferous Forest, the Eastern Deciduous Forest, the Desert, the Grasslands, and the Tundra biomes. A study of a sixth biome, the Tropical Forest Biome, recently began functioning. Comprehensive aquatic programs have been conducted in all biomes with the exception of the Grasslands. A one-year program of aquatic research, at Colorado State University, did occur in that biome. Modeling has emerged in the aquatic research activities as a common thread and directive force for program integration and research development. Historically, the goals, approaches, and model types in each biome were dissimilar. Some employed ecosystem (total) models which are broad in their resolution; others used questionoriented models in relation to resources use, or process models for physical or biological activity within the system. Representing ecology in terms of mathematical expression occurred well before the birth of the IBP (1930-1940). But these early models were simplified process expressions and somewhat unrealistic. The complexity of any ecosystem made it almost impossible for realistic mathematical modeling to occur in those times. However, faster digital computers and other advances in technology allowed the real dynamic processes of ecosystems to become defined for numerical solutions. Although the expression of an aquatic environment might be most real for a very detailed or individual organism model, the sensitivity and precision for total ecosystems using this approach have not been acceptable. Thus, the choice and use of process, question-oriented, or total ecosystem models arose. I n some biome studies, models have been developed for many of the physical, chemical, and biological processes. These detailed process models have been incorporated into total ecosystem models. Biome aquatic studies
The Tundra Biome commenced its integrated program in mid-1970. I t has concentrated on natural and exogenously disturbed (e.g., oil-spilled) ecosystems in the wet arctic tundra to establish an understanding of ecosystem adjustment after periods of perturbation. The aquatic research has been conducted at the Barrow Ponds and lkroavik Lake (Alaska). A dominating factor for all biologic processes in this biome is brevity of the growing season which varies between 45-90 days. However, uninterrupted light compensates for this phenomenon to some degree. Also, it is notable that the tundra ponds demon708
Environmental Science & Technology
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strate that since Droduction is nearly eaual to extended decomposition (total) rates, a lack -of accumulated net organic matter results. The research teams have amassed enormous amounts of ecologic data from their studies and have structured a total ecosystem model based on past experiences of other biome modeling studies. The Desert Biome has investigated abiotic and biotic systems to build question-oriented submodels which attempt to provide a series of relationships closely allied to organism function within the ecosystem. Research sites at Locomotive Springs (Utah) and Deep Creek (Idaho) have received the most attention in this biome's aquatic program. The Saratoga Springs (California) saline aquatic research site is located at the southern tip of Death Valley and constitutes an aquatic ecosystem within the Mohave desert. The similar environment of the Locomotive Springs site has afforded a comparator system to the Saratoga Springs study. To some extent, the modeling efforts of the desert biome have been quite detailed and structured toward question-oriented models, since the vulnerability of these fresh waters to rapid changes and undesirable utilization occurs regularly. Recently, the excessive detail within the desert models has been reduced to permit model testing to occur more practicably for those aquatic ecosystems being monitored. In the Coniferous Forest Biome, a major aquatic program has been ongoing since its field program began in 1971. The four lakes' study (Chester Morse, Findley, Sammamish, Washington) has included specific tasks for assessing forest and urban land-use influences, energy sources for aquatic food chains, the structure and metabolism of communities and their nutrient budgets, effects of food and fish on various tropical levels, effects of one fish population (anadromous fish) on other fish populations, and the outputs of the anadromous fish to marine communi ties. The processes that have received intensive examination within the Coniferous biome's lake study program include seven studies associated with the water column. The relationships of these seven subsystems have been modeled to explain production dynamics-phytoplanktonzooplankton-nutrient interrelationships both in time and with water depth-throughout the water column. Also, the abiotic dynamics of nutrients and bacterial cycling of carbon are integral parts of these submodels. Other studies associated with bottom-related processes in lakes and the characteristics of consumer chains in the aquatic sequence of food webs were formulated. These additional descriptions afforded scientists quantitative comparisons of cycling phenomena in the lakes and handled questions on the structure and flow of energy within these ecosystems.
One of the four study lakes, Findley Lake, comprised a study of land-water interfaces in a pristine, oligotrophic lake. Studies of this system were directed at both terrestrial and aquatic environments and involved nutrient availability for primary, secondary, and tertiary producers. The singular similarity for the total study, however, has been water in the form of precipitation, surface water flow, stream and lake waters within which nutrients, principally from allochthonous (outside the lake) sources, reside and are thus available to the biota. This interface phenomenon provided interesting connections between the terrestrial/aquatic couplings in the Findley Lake watershed as well as providing a linkage between this study site and the efforts of the stream watershed projects at the H. J. Andrews Watershed Stream Study site (Oregon). The studies at Andrews were concentrated in Watershed = l o , Mack Creek and Lookout Creek. The role of the biota in the small streams concerning their metabolic activities and successional changes relative to allochthonous nutrient inputs (particulate and dissolved) was emphasized. The long-range goal of this aspect of the Coniferous Forest biome study has been to understand the role of a stream in ecosystem function and to determine the alterations in structure/productivity relationships as a result of a specific land-use pattern. I n the Eastern Dieciduous Forest Biome (EDFB), the aquatic studies have concentrated on achieving the I BP's objectives of better ecosystem understanding and the prediction of consequences from man-induced changes. Thus, the biome bias emphasized the development of aquatic models that possess built-in mechanistic capabilities for forecasting the various effects of man's activities. Also, these models were constructed to portray a perception of ecosystem science from the multidisciplinary investigations of the programs. These mechanistic aquatic models have acted as a resource for the EDFB in testing the dynamics of the total ecosystem. The research has resided at two sites-Lake George (New York) and Lake Wingra (Wisconsin). Each site has, individually and in (concert with its sister-site, combined its research efforts in developing very practical process, site-specific. and total aquatic ecosystem models. The last may, in fact, be the most advanced aquatic model presently available. These models in the EDFB are based upon the incorporation of data from biome studies on the numerous process components associated with these lakes, or any aquatic: ecosystem, for that matter. One of the more abstract programs not only focused on site research in the EDFB, but has had dimensions to ensure realism which included site investigations for insight into systems 'operation at higher geographical levels, regional land-use simulation analyses, and geological data. This program. the Biome and Regional Analysis Program, has been concerned with entire landscapes where the horizontal proportion of ecosystem types and the change of area from one type to another through time is the essence of system dynamics. The aquatic studies at the Lake Wingra site have occurred in a small shallow eutrophic lake that experiences year-round urban, suburban, and recreational impacts. The process research at both lakes has not only complemented one another. but has offered a distinct means for comparison and contrast. since Lake George can be characterized as an oligotrophic-mesotrophic system, primarily experiencing recreational use and relatively high population densities o n a seasonal basis only. The specific research has involved the subject areas of aquatic primary production, secondary production, decomposition and nutrient cycling, physical systems (climatology and hydrology), and land-water interactions. An outgrowth of .these biome investigations has begun to take shape in the actual application of the subsystem
Stanley P. Gessel David W. Goodall & Frederick H. Wa
Otto T. Solbrig Otto T. Solbrig Harold A. Mooney
Dieter Mueller-Dombois Richard C. Dugdale
models and the biome model to perturbations very real in today's society. For example, a soecific amlication of the bluegill fish model for the Lake 'Wingra ;esearch site to thermal gradient exposure from a power plant effluent has demonstrated fish congregation near the warm water outfalls, with a concomitant loss in weight for these fish as a result of crowding and consumer competition. Although these effects appear relatively harmless to the fish population from a single outfall, additional power plants would exert undesirable effects. Aquatic models
The pelagic zone (free open water) model for Lake Wingra (WNGRA2) is a site-specific model of mixed levels of resolution. I t is geared to a shallow lake system, and its components are very similar to the total biome model. However, some of the subroutines are quite varied in their composition, relative to those of the total model. The principal difference has been that this model did not require a lessening in detail in some components of the ecosystem since it represented the pelagic zone only. WNGRA2 has been linked to the biome's hydrologic transport model ( H T M ) , giving the researchers the opportunity to examine nutrient influx into the pelagic zone of the lake and the resulting response of its bio-components. However, the influence of the littoral (near shore) or marsh areas on nutrient influx has not been considered, and these lake zones undoubtedly play a significant role in this phenomenon. The response in the pelagic zone during springtime is dependent primarily on the amount of rainfall received, nutrient regeneration from bottom sediments, and phosphorus tied up in fish biomass. Other internal subcomponents are the principal sources of the nutrients for the remainder of the year. Under these circumstances, where
Aquatic sites supplying data for CLEAN Water body
Char Lake Lake Georgec Yorderer-Finstertaler See Marion Lake Lake George Lake Wingrat8
Location
Canada USA (New York) Au str la Canada Uganda USA (Wisconsin)
OThese lakes currentlycan be simulated withCLEAN.
Volume 8. Number 8, August 1974
709
large pools of nutrients exist within the lake, the effect of nutrient input reduction by diverting sewage effluent or nutrient stripping from the lake may be minimal or possibly undetectable as a result of internal nutrient regeneration. The development of models able to forecast the effects of eutrophication has culminated in the biome's total aquatic ecosystem model. This formulation, known as Comprehensive Lake Ecosystem ANalyzer (CLEAN), has been applied to both Lake George and Lake Wingra. and is being further tested with data from several lakes and reservoirs which represent PF in the IBP. In fact, CLEAN and a Canadian IBP model form the basis of a generalized model for the entire aquatic program of the IBP. This model has been tested with data from six lakes and reservoirs in the U.S./lBP biomes and foreign countries. In addition, the Lake George site modeling team, in cooperation with M. Brylinsky of Dalhousie University (Nova Scotia), has been applying analytical techniques-cluster analysis and ordination-to data from 86 lakes and reservoirs that represent IBP/PF. This has been a major synthesis of information regarding international aquatic systems on which future aquatic system management might rely heavily. CLEAN has been structured as 28 coupled ordinary differential equations and mimics most biological processes of interest in research studies of eutrophication. Attention was directed in the model's programming for component interaction and to permit the adaptation of new components as they become needed. The driving variables for CLEAN include nutrient concentrations, wind or barometric pressure gradient, incident solar radiation, water temperature, and allochthonous dissolved and particulate organic matter. The model is programmed to allow scientists to execute any specific submodel or link any meaningful combination of submodels. This has permitted the function of the ecosystem, as a whole as well as portions of it, to be examined at will. Although the model may be one of the most versatile and detailed lake ecosystem models in existence and possibly the most advanced aquatic model available, it reauires some additional linkaae to Dermit actual predic-
James J. Ferris 8s me research coorainilror o l me Rcnsselaer Fresn Vialer lnsrdure ar Lake George tic has paroopared !n me reseafcri acrtirrres N mi,! ine Easrern Dec8ouoi.s
execufive commiffee for fhe Easfern
tion. However, because CLEAN embodies a great deal of ecologic realism in its mathematical formulation, it can be applied as a highly effective diagnostic tool to facilitate the way by which aquatic ecosystems function-that which would not conform to direct examination because of the complexity of component linkages and feedback loops. Mode11s that can be used for routine environmental managelment do not require the complexity found in .. .. .~ .-.,. . 1 .. . "...L V V I V U ~ H L I S an exarripie U T sutin a I I I U U ~ I . firiv~rtCLEAN. ,.,.,"-"" er model strongly influenced by CLEAN is SIMPLE (SIMPlified Lake Ecosystem) which, although designed for Lake George (New York) simulation only, will permit, with slight modifications, applications to most lakes with excessive phosphate loading. The state variables do not portray the detailed ecologic groupings characteristic to CLEAN, and the time step is weekly. Although SIMPLE considers only the most significant transfers, the results fr om it have been encouraging. -.>.I
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Additi onal reading Blair. W. F., "The Environmental Challenge," pp 264-74. Holt, Rhinetiart. and Winston, New York, N.Y., 1974. BIoomfidd .I-. .A.., at _.11_.., "Modelinn ...___....i. the Fiitrnnhiritinn .Prnress Pro
