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<br />. FEB 05 '90 17:)0 <br /> <br />P,ll <br /> <br />study or tood and changing habitat conditions. and fish <br />reproduction under various discharge regimes. <br />Inte~reletionships between native and introduced fish <br />epeclea will be Buggested based upon the POPulation and <br />reproduction dynamics of each species. <br /> <br />The tollowin~ secondary hypotheses will be tested using the <br />research program established to test H.-5.l. <br /> <br />H.-~.la. Th~re is no significant relationship between <br />populatlon dynamlCS,of native and introduced fish species in the <br />mainstem Colorado, lncluding backwaters and tributaries and the <br />magni tude of discharge fluctuations. . <br /> <br />K.-6.1b. There is no significant relationship between <br />po~ulation dynamics of native and introduced fish species in the <br />malnstem Colorado, including backwaters and tributaries. and the <br />magnitude of minimum discharges. <br /> <br />7. Question: How are water quality (nutrients and other <br />characteristics) and stream productivity (algae and <br />invertebrates) affected by discharq8 fluctuations. and the rate <br />ot change in fluctuating discharges. <br /> <br />8.-7.1. There is no significant relationship betwaen <br />nutrient availability, productivity (of algae and <br />macroinvertebrates) and import-export rates of organic matter to <br />and from the Lee's Ferry reach, and the magnitude of discharge <br />fluctuations, and the rate ot change of fluctuating discharges. <br /> <br />Justification: Lake Powell serves as an effective nutrient <br />and sediment trap, removing more than 90% at the sediments <br />and associated phosphorus entering the reservoir. <br />PhosphOrus has been implicated as the potential "limiting <br />nutrient" for primary productivity 1n colorado River <br />reservoirs and downstream tailwaters. Deep, hypolimnetic <br />releases from the dam may contain higher concentrations of <br />phosphorus than waters drawn from higher levels in the <br />reservoir, but they are aleo considerably colder during much <br />of the year and higher in salinity. <br /> <br />Nutrient Ivailability in the Colorado River below Glen <br />can~on Dem is determined by input concentrations and volumes <br />dellvered from the dam and downstream tributaries (loading). <br />and by production and regeneration (recycling) processes <br />which occur in the river. Flows from fluctuating discharges <br />appear to increase the amount of organic drift in the river <br />through detachment and through stranding and desiccation <br />which contribute to the mortality of algae, invertebrates <br />and fish. Daily fluctuations, in conjunction with the <br />volume of discharge, also have the capacity to set limits on <br /> <br />11 <br />