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SSQ 1 -2 Does a decrease in the abundance of rainbow trout and other cold- and warmwater <br />nonnatives in Marble and eastern Grand Canyons result in an improvement in the recruitment rate of <br />juvenile HBC to the adult population? <br />SSQ 5 -1 How do dam release temperatures, flows (average and fluctuating component), <br />meteorology, canyon orientation and geometry, and reach morphology interact to determine <br />mainstem and nearshore water temperatures throughout the CRE? <br />Development and testing of EwE models for food web interactions in the aquatic communities will <br />occur in the Lees Ferry and Little Colorado reaches of Grand Canyon. This will involve continued <br />development and fitting to historical abundance trend data of EwE models developed during FY2009 in <br />cooperation with GCMRC scientists. Model parameter estimates will be refined using information <br />provided by GCMRC cooperators, and formal parameter estimation procedures will be applied to <br />estimate key production parameters by fitting the models to historical fish population trend data for <br />1990 through 2009. <br />The Grand Canyon Ecosystem Model (GCEM), developed in the late 1990s through collaboration <br />between Ecometric Research and the GCMRC (see Walters and others, 2000), will be used to <br />reconstruct historical changes in the Colorado River food base for native and nonnative fish associated <br />with changes in diurnal flow regimes and turbidity conditions caused by tributary sediment inputs. The <br />EwE food web models need to be fitted to historical abundance trend data, and that model fitting will be <br />misleading unless the EwE models are provided with realistic time forcing data on past changes in <br />primary and secondary (insect, amphipod) production owing to change in turbidity. The GCEM model <br />will be run with historical tributary sediment inputs and refined estimates of regrowth rates of primary <br />producers following periods of low productivity because of high turbidity to provide monthly estimates <br />for 1990 through 2009 of food biomass likely to have been available to native and nonnative fish in <br />reaches of Grand Canyon near and below the Little Colorado River. <br />Ongoing collaboration with University of Florida and State University of New York at Syracuse will <br />evaluate pilot study results from flannelmouth sucker (Catostomus latipinnis) otolith analyses and <br />employ geochemical signatures in water and native fish otoliths to infer natal origin, tributary habitat <br />use, and migration patterns. The project will conduct pilot analyses of flannelmouth sucker otoliths and <br />water samples collected in fiscal year 2008. Preliminary analyses of the water samples suggest <br />promising uniqueness among Colorado River tributaries for describing patterns in flannelmouth sucker <br />otoliths associated with ontogenetic shifts in tributary versus Colorado River occupancy. These analyses <br />above will tie into the nearshore ecology project with the objective of troubleshooting field methods and <br />data analysis procedures, with particular emphasis on assessment of changes in native fish dispersal and <br />survival rates in relation to changes from fluctuating to fall steady flows. <br />Reporting and Synthesis <br />Results of individual projects will be presented in the various reports or publications that are listed in <br />each project description. We will also produce an overall summary report to be delivered by January <br />2013 that summarizes and synthesizes the results of all projects with respect to the FSEF. The cost to <br />produce this report (workshop with relevant scientists and managers, 2 to 3 months salary for one GS -12 <br />to GS -14 scientist to lead writing, and publication costs) is estimated to be about $50,000. <br />15 <br />