. The changing Illinois environment : critical trends : technical report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. I:!:!:!:!:!l ESJ" â â " ED l>:: : i CD- >.-::-1. -CD CD ED- ED rTTTTTl CD CD CZZZZCZ --ODD CD - E3 CCZD----CD -CD CD-- â-CD CD ED- CD CD -CD -CD --cd r~^~i E3 -CD -CD ED" ED-- E3 CD â CD CD 100 0 909 909 * Black bars indicate species that occurr
. The changing Illinois environment : critical trends : technical report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. I:!:!:!:!:!l ESJ" â â " ED l>:: : i CD- >.-::-1. -CD CD ED- ED rTTTTTl CD CD CZZZZCZ --ODD CD - E3 CCZD----CD -CD CD-- â-CD CD ED- CD CD -CD -CD --cd r~^~i E3 -CD -CD ED" ED-- E3 CD â CD CD 100 0 909 909 * Black bars indicate species that occurred over 90% of years. Stippled bars indicate species that occurred in less than 90% of the years. Dashed lines indicate years when electrofishing was not conducted. Ten species were consistently collected in 90% or more of all years, which includes pollution-sensitive centrarchid species (, largemouth bass, bluegill, black and white crappie) as well as white bass. In sharp contrast to the other sections of the river, goldfish and carp x goldfish hybrids, non-native pollution-tolerant fishes, were collected in few years, an indication that the lower waterway suffers less from urban and industrial wastes. Small minnow species (, red shiner, sand shiner, spottail shiner, bluntnose and bullhead minnows) were less consis- tently collected from the lower waterway than the upstream sections, which could reflect differences in habitat conditions (, fewer aquatic plants for use as cover than in the upper waterway, fewer backwaters than in the middle section, the leveeing and draining of the floodplain) or other factors as yet undetermined. critical spawning and wintering habitats and conditions can be identified and preserved. Also, the population of large fish may be quite small, but the fish are concen- trated and easily caught during low water levels because they are forced out of backwaters made shallow by excessive sedimentation. If this is the case, then length res
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Keywords: ., bookcentury1900, booksubjecte, booksubjectecology, booksubjectman
