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measurable current except when there was wind blowing into them. Except for their <br />lack of vegetation they were very similar to the littoral region of a lake. Unlike the <br />main river channel of the Green River, backwaters seem to be quite productive. This <br />productivity probably attracts fish to the backwaters, which provides the opportunity to <br />test their effect on the invertebrate community. <br />Direct effects <br />The taxa which experience the greatest direct effects of fish predation appear to <br />be the chironomid genus Tanypus, the corixidae, and the planktonic adult copepoda <br />(including the predominant species Eucyclops s era u ). The corixidae and Tanypus <br />are both predators (the Tanypus may be omnivorous, see Merritt and Cummins 1984). <br />The predominant copepod genus, Eucyclops, is predominantly herbivorous (Wetzel <br />1983). All three groups were generally lower in the control areas and higher in the <br />perforated and closed areas where fish predation was diminished or absent. However <br />by week five there was a drop in adult copepod numbers which was less pronounced <br />in control areas than in the other treatments (Table 4). <br />It is possible that the elevated numbers of corixids in perforated and closed <br />treatments were a result of the insects crawling through the mesh in search of refuge <br />from predation or wind generated currents. We measured several anatomical <br />characters (including head capsule width) of corixids caught in perforated and closed <br />cages and found 76% of the individuals measured were first or second instars (which <br />are small enough to fit through the mesh). However, the few corixids caught in control <br />areas were all early instars as well. Whether increased densities of corixidae in caged <br />11