. The changing Illinois environment : critical trends : technical report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. Figure 28. Distribution ofCyprinella lutrensis (left) and Cyprinella spiloptera (right). Open circles denote 1908 locality records; solid circles denote locality records from 1950 to 1969. The shaded areas in the left figure indicate the major range expansions that occurred from 1908 to the present. The shaded area in the right figure indicates the range reduction that occurred from 1908 to the pres
. The changing Illinois environment : critical trends : technical report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. Figure 28. Distribution ofCyprinella lutrensis (left) and Cyprinella spiloptera (right). Open circles denote 1908 locality records; solid circles denote locality records from 1950 to 1969. The shaded areas in the left figure indicate the major range expansions that occurred from 1908 to the present. The shaded area in the right figure indicates the range reduction that occurred from 1908 to the present. Fish: Illinois River Background. The Illinois River belongs to a world class of large river-floodplain ecosystems, where biological productivity (including fish yield) is enhanced by annual flood pulses that advance and retreat over the floodplain and temporarily expand backwaters and floodplain lakes (Junk et al. 1989, Sparks et al. 1990, Sparks 1992). The expanded aquatic habitats are utilized as feeding areas by migratory birds and as breeding areas and nurseries by fish and other aquatic life. The Illinois River today is the largest river (in terms of water flow) contained mostly within the state, and its fish populations reflect urban influences from the state's largest metropolitan area (the Chicago- Joliet area) as well as effects of land-use practices in the corn belt that runs across the middle of the state. The river is divided into five reaches by navigation dams, including the Alton Dam (Dam 26) on the Upper Mississippi River, which influences the lower 80 miles of the Illinois River (Figure 33). These five reaches in turn fall into three major sections, defined by the natural physiography of the river and by the degree and nature of human alterations. The Dresden, Marseilles, and Starved Rock reaches together form the upper Illinois River, characterized by a geologically young channel with a relatively narrow floodplain between rocky bluffs. This section has b
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Keywords: ., bookcentury1900, booksubjecte, booksubjectecology, booksubjectman
