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<br /> <br />Tab]e 11. The m.ljor ioU-rnd] physic~] fiIC:tors affl'cting the White <br />River SYSI l'fTl. <br /> <br />thus far 1 <br />periphytOl <br />substrate! <br /> <br />A. Channel ~womorphol ogy <br /> <br />(1) Elevational change (slope). <br />(2) Cross 6l?ct10na] df:pth distributions. <br />(3) Cross sectional \ol'stt:r velocity distributions. <br /> <br />(a) Current. <br />(b) Turbul ence. <br /> <br />(~) Substrate. <br /> <br />(a) Size. <br />(b) Texture. <br />(c) Chemical composition. <br />(d) Stability. <br /> <br />(5) Channel meander rate. <br />(6) Pool to riffle ratio. <br /> <br />B. Fluv1tile (water) characteristics <br /> <br />0) Heat (temperature) <br />(2) Chemistry. <br /> <br />(a) Dissolved gases. <br />(b) Dissolved substances. <br />(c) pH. <br /> <br />(3) Turbidity and silt load. <br /> <br />ambient physical system was predictably modified. with <br />concurrent effects on the biological community. <br /> <br />Changes in current and turbulence can shift and <br />restabilize the bed in the White River. This dynamic <br />process can produce molar action that may physically <br />damage animals and modify habitat types (pools. runs. <br />riffles). Periods of high discharge or storm events will <br />produce greater habitat modifications than normal. <br />baseline water level currents. It should be noted that in <br />sections of the White River where shifting stream bottoms <br />are encountered. the configuration of canyon walls or <br />large boulders may be important in creating permanency in <br />deflecting currents in a predictable manner. <br /> <br />Even ame <br />been 01 <br />probabl) <br />the dl! <br />which n <br />study <br />chemist] <br /> <br />Substrate stability is dependent on current velocity <br />(Bull. 1981). Biologically. substrate stability relates <br />to the organisms which use the benthic region for <br />attachment (periphyton. macroinvertebrates). The <br />current-determined substrate size also determines the size <br />of organic particles (food for higher organisms) caught <br />within pore spaces (Farnworth. 1979). The substrate type <br />(size. texture. and chemistry) may at times influence the <br />distribution of benthic algae and invertebrates in streams <br />(Whitton. 1975). Large. stable. rocky substrates have <br /> <br />Th~ <br /> <br />stochas' <br />hence. <br />suspend <br />photosy <br /> <br />272 <br />