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<br />~w <br /> <br />D. Measure concentrations of selenium and other inorganic <br />contaminants in: <br />t. Water (grab, integrated) <br />2. Sediment (core, dredge) <br />3. Benthic invertebrates (core, dredge) <br />4. Limnetic organisms (light traps, plankton netl <br />S. Fish: <br />a. Species present in the North Pond prior to their removal <br />b. Stocked razorback suckers <br />c. Species composition in main channel area both before and <br />after installation of the water control structure <br />d. Larval sampling in the channel area <br />E. ~onitor the following parameters at each sampling site: <br />t. General water quality parameters (including alkalinity, <br />ammonia, calcium, chloride, conductivity, dissolved oxygen, <br />hardness. magnesium, nitrate, nitrite, pH, sulfate, and <br />turbidity) . <br />2. Sediment texture (particle size analysis) and chemistry. <br />3. Water and sediment discharge into and out of the restoration <br />sites. Water flow measurements will be related to stage and <br />discharge measurements at gaging stations on the Colorado <br />River. <br />4. Primary productivity. <br />5. Semi-quantitative estimates of benthic and plankton <br />abundance and species diversity. <br /> <br />NOTE: Assistance in collecting routine monthly samples as described <br />above in 0 and E will be from Bureau of Reclamation. Grand <br />Junction Area Office. <br /> <br />Task 2. Evaluate survival and reproductive success of razorback sucker <br />adults stocked in restored sites. <br /> <br />Rationale <br />Field and laboratory studies have shown that selenium has the <br />propensity to be strongly bioaccumulated in aquatic food chains. Low <br />waterborne concentrations of selenium can result in elevated selenium <br />residues in food organisms that are toxic to fish that consume them. <br />The purpose of this study is to determine if ambient concentrations of <br />selenium in the water and food-chain organisms in restored habitats <br />adversely affect the reproductive success of razorback suckers. <br /> <br />Procedures <br />The reproductive success of razorback suckers will be determined in <br />the restored sites (Walter Walker State Wildlife Area and Adobe Creek) <br />and also at the reference site if adult fish are available for <br />stocking from the Colorado River FiShery Project (CRFP). It is <br />desirable to have several sites with different levels of selenium (and <br />other inorganics) contamination in order to obtain a concentration- <br />response relation. <br />Prior to stocking the fish at the sites, fish will be PIT tagged, <br />measured for total length and weight, and muscle plug samples taken <br />for selenium (and other contaminants if needed) residue analysis. The <br />number of fish to be stocked at a given site is contingent on the <br />number of adults available and their genetic compatibility, but <br />ideally enough fish should be stocked to provide at least five <br />spawning pairs for assessment of reproductive success. The fish <br />should be stocked as early as possible to allow them to accumulate <br />selenium residues from both water and dietary sources before spawning. <br /> <br />At 30-day intervals after stocking, tne fish will be sampled in <br />cooperation with the CRFP. Captured fish will be identified from <br /> <br />BC-l~-D <br />