9389 - Laserfiche WebLink

Home Browse Search

n L~ ~ EXECUTIVE SUMMARY ~ Floodplain wetlands are highly productive segments of the riverine ecosystem. • They exhibit higher temperatures, nutrient concentrations and light intensities than river channel habitats, resulting in an overall increase in food productivity. In the Colorado ~ River system these wetlands may provide important rearing habitat for young-of-the- ~ year (YOY) native species, including the endangered razorback sucker (Xyrauchen • texanus). Fish inhabiting these areas grow rapidly because of greater food abundance. Consequently, survival of native YOY fish that return to the mainstem river from these ~ areas may be enhanced. Floodplain wetlands may also be important resting and ~ feeding areas for adult native fishes. ~ Because of information linking razorback sucker life cycles to floodplain habitats, the Upper Colorado River Endangered Fish Recovery Program (UCRRP) initiated a ~ floodplain acquisition and enhancement program. Levee Removal is just one ~ component of the UCRRP floodplain restoration program. The goal of Levee Removal ~ and this study was to restore and enhance floodplain wetland habitats and functions • (via levee removal) that support recovery of endangered fishes in the Upper Colorado River Basin. The specific objectives of this study were to: ~ 1. Reconnect selected floodplain sites with the river channel. ~ 2. Evaluate the system responses to levee removal. ~ FY - 1996 • Designated year to collect baseline data prior to levee removal. ~ FY-1997 - 1999 ~ a. Determine if native or nonnative fish utilize inundated floodplain habitats (and ~ the associated river channel) differentially (proximate response). ~ b. Determine if native and/or nonnative fish increase in areas (river reaches) of ~ high floodplain habitat inundation (ultimate response). ~ c. Determine if native and nonnative fish responses to floodplain inundation are ~ different in river reaches that originally had high or low nonnative fish densities ~ (based on current estimates). ~ d. Determine if native fish habitat utilization, growth, and survival are negatively ~ correlated with nonnative fish responses. ~ e. Determine if floodplain habitats result in an increase in food resources • available for native or nonnative fishes (either in the inundated areas or the adjacent river channel). • xi