Freshwater Ecosystems Revitalizing Educational Programs in Limnology (1996) / Chapter Skim
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Organizing Paradigms for the Study of Inland Aquatic Ecosystems
Organizing Paradigms for the Study of Inland Aquatic Ecosystems
Pages 181-202
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From page 181... ...
These include the concept of lakes as microcosms, wetlands as ecotones or "gradient ecosystems," and the River Continuum Concept. In recent years, the importance of terrestrial-aquatic interactions has been widely recognized, and a paradigm common to all classes of inland aquatic ecosystems regards them as reflections or integrators of conditions in the watershed in which they are located.
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From page 182... ...
than studies of flowing waters and wetlands.2 In addition, the discrete, semiclosed nature of lake basins, compared with the open, flowing nature of streams and the often diffuse boundaries of wetlands, makes it easier to view lakes as appropriate objects of scientific study. Lake studies have always been approached holistically to include physical, chemical, biological, and geological aspects, even though biologists conducted most of the early work.
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From page 183... ...
He proposed that lake studies should focus on many of the ecosystem-level Processes that define the late twentieth century field of ecosystem ecology: the circulation of elements and substances (now called biogeochem~stry) , the production and decomposition of organic matter, food web interactions (especially predator-prey relationships)
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From page 184... ...
Juday also was trained as a biologist and was first hired by Birge in 1897 to help conduct lake surveys for the newly established Wisconsin Geological and Natural History Survey, of which Birge served as the first director. However, Birge and Juday soon branched into the physics and chemistry of lakes as they realized that orate could not understand the dynamics of plankton without knowledge of these subjects.
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From page 185... ...
, chemical concentrations (nutrients) , and biological characteristics (species types and abundance and primary production)
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From page 186... ...
Examples include the first~whole-lake experimental acidification' which involved a small bog lake (Zicker, 1955~; aeration-induced destratification experiments on several eutrophic lakes (Schmitz and Hasler, 1958~; and the addition of short-lived radioisotopes to the water of stratified flakes to measure rates: of water movement (e.g., Likens and Hasler, 1960~. Hasler's group also pioneered the use of small artificial ponds (wading pool size)
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From page 187... ...
tracer additions to measure rates of physical processes, such as use of radiotracers to determine water movement and sulfur hexafluoride (SF6) and noble gases to monitor air-water has exchange.
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From page 188... ...
The transfer of CO2 across the air-sea interface has been a major topic of research for many years in relation to global climate Eutrophication is the nutrient enrichment of lakes that results in an array of symptomatic changes, including an increase in primary production and in the abundance and composition of phytoplankton and other aquatic organisms, and a decrease in water clarity. Some of these changes are considered objectionable and limit the usefulness of the lake for recreational purposes (e.g., swimming, fishing)
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From page 189... ...
, and on Pleistocene Lake Lahontan in western Nevada (Russell, 1885~. Stratigraphic studies on the sediments of modern lakes to reconstruct historical conditions date back at least to the 1920s.
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From page 190... ...
, and more recently, various organic pollutants and trace elements whose biogeochemical cycles have been influenced by human activity. Aver the past 30 years or so, stratigraphic analyses of long cores of lake and wetland sediments have provided important information on regional variations in past climatic conditions and watershed vegetation patterns, from which paleoecologists have sought to answer fundamental questions about the causes of environmental change, including questions of species extinction (e.g., Deevey, 1967~.
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From page 191... ...
As concern grew during the mid-twentieth century about the effects of excessive nutrient loadings on lake ecosystems and lake water quality, engineers and limnologists began to quantify these loadings in the form of nutrient budgets. Water budgets, of course, were found to be a necessary part of such studies, and these efforts gradually led to an increased awareness of the importance and closeness of the interactions between lakes and their surrounding landscape, including littoral or contiguous wetlands (Wetzel, 1990, 1992~.
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From page 192... ...
. Finally, the subject of ecosystem energetics has been a major organizing tool in ecology for more than 50 years, since Lindeman published his classic 1942 study of "trophic dynamics" energy flow through the food web in Cedar Bog Lake.
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From page 193... ...
For the most part, stream limnology has been identified most strongly with stream biology, but even here, practicing stream biologists often are identified more with other "parent disciplines" such as public health biology (sanitary microbiology) and fisheries biology.
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From page 194... ...
Classification of flowing waters according to stream order, based on their relative position in the typically dendritic (beelike) or hierarchial network in which streams are connected in a large river basin, is a longstanding organizing principle in both hydrology and geomorphology.
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From page 195... ...
The RCC views entire fluvial systems as a continuously integrated series of physical gradients and adjustments in the associated biota (Cummins et al., 19951. Geomorphological and hydrological characteristics provide the fundamental physical template, which changes longitudinally within a drainage basin from the headwaters to the river mouth in a predictable fashion.
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From page 196... ...
These include the nutrient spiraling concept, in which the unidirectional downgradient flow of streams causes nutrient cycles to be open rather than closed, so that there is a gradual downstream displacement of nutrients, the rate of which is controlled primarily by flow. Other paradigms, such as the patch dynamics concept, which were viewed initially as counter to the RCC, were later shown to be compatible with a broader vision of the RCC that considers both temporal and spatial factors as influences on stream ecology.
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From page 197... ...
In addition, the trophic-dynamic concept and concepts of energy flow and nutrient cycling play the same role in wetland ecology as in lake and stream ecology. Wetland science also has developed several organizing paradigms beyond those of the disciplines on which it is based and the general paradigms of aquatic ecology: .
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From page 198... ...
Several major research programs have been developed in association with academic institutions and water management agencies to study the effectiveness of wetland systems ire removing nutrients and other contaminants from domestic waste effluent (e.g., Ewel and Odum, 1984) or in purifying stormwater runoff before it reaches lakes and streams (e.g., Olson and Marshall, 1992~.
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From page 199... ...
1989. Randomized intervention analysis and the interpretation of whole ecosystem experiments.
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From page 200... ...
1970. Effects of forest cutting and herbicide treatment on nutrient budgets in the Hubbard Brook watershed-ecosystem.
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From page 201... ...
1956. Primary production in flowing waters.
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From page 202... ...
1992. Cradient-dom~ated ecosystem Sources and regulatory Cinchona of dissolved organic matter in eater ecosystems Hydrobiologia~229: j81-189.
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