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Freshwater Ecosystems: Revitalizing Educational Programs in Limnology
TABLE 3-1 Some Significant Discoveries Concerning the Effects of Atmospheric Deposition On Aquatic Ecosystems, 1957-1995
Showed the degree of acidification of English lakes to be related to substrate geology
Recognized the relationship among acid rain, surface water acidity, and disappearance of fish in Norway
Woodwell et al.
Reported biological magnification of DDT in aquatic food chains
Winchester and Nifong
Indicated atmospheric precipitation as an important source of trace metals in Lake Michigan
Almer et al.
Showed a reduction of biodiversity in phytoplankton, zooplankton, and fish in acidified Swedish lakes
Murphy and Rzeszuko
Found atmospheric deposition to be an important source of PCBs to Lake Michigan
Ferguson et al.
Implicated air pollution and associated acid deposition in the disappearance of Sphagnum mosses from northern English bogs during the industrial age
Cronan and Schofield
Showed toxicity to fish of aluminum released from soils by acid deposition
Davis and Berge
Inferred pH profiles in dated cores of lake sediment from diatom stratigraphy
Schindler et al.
Demonstrated that adverse effects of acid deposition on fish can occur via harm to food organisms
Wright et al.
Showed rapid recovery of catchments following reduced acid loading
Muir et al.
Demonstrated high concentrations of organochlorine contaminants in arctic marine fauna due to long-range transport and bioaccumulation
have been introduced into regions to which they are foreign. Other cases involve the shifting of species distributions within narrower geographic regions. In either situation, introduced species can have substantial effects on aquatic habitats; they may shift the occurrence or abundance of native species, change important ecosystem functions, and interfere with desired human uses of the water body. Limnologists are important in developing assessments of the consequences of inadvertent introductions. They also can play a key role in the development of realistic predictions for intentional introductions. Finally, limnologists can help create management strategies to minimize the impacts of introductions that have already taken place.
Many exotic species, including the sea lamprey, alewife, and zebra mussel, have invaded the Great Lakes over the past century. In response, a variety of nonnative fish species have been introduced intentionally, in some cases to control invading species and in other cases to replace fish eliminated by the invaders. Many of the invading species entered the