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these habitats because high residence time might allow for a water column food web to develop and <br />might also allow for benthic algae and invertebrates to accumulate. <br />Strategic Science Questions <br />Primary SSQ addressed: <br />SSQ 3 -5. How is invertebrate flux affected by water quality (for example, temperature, nutrient <br />concentrations, turbidity) and dam operations? <br />Information Needs Addressed <br />CMIN 1.5.1 Determine and track the composition and biomass of drift in the Colorado River in <br />conjunction with measurements of flow, nutrients, water temperature, and light regime. <br />EIN 1.1.1 How does primary productivity in the reach between Glen Canyon Dam and the Paria <br />River change in response to an experiment performed under the Record of Decision, unanticipated <br />event, or other management action? <br />Methods and Tasks <br />Primary production is already being measured continuously in Lees Ferry and at Diamond Creek (RM 0 <br />to 226). Primary production data collected during September and October 2008 -2012 will be compared <br />with the months before and after to determine whether steady flows affect rates of in- stream primary <br />production. Organic and invertebrate drift is measured monthly at Lees Ferry. To determine whether <br />steady flows affect drift rates we will compare data collected in September and October 2008 -2012 with <br />the months before and after. As part of the 1D funding, the food base project began intensive study of <br />backwaters on their April 2008 river trip. Data being collected in backwaters includes primary and <br />invertebrate production and dye - tracer studies to determine water residence time. Because data <br />collection in backwaters began in April 2008, we do not have data on biological parameters from <br />previous years to compare with 2008 fall steady flows data. However, water residence time will only be <br />affected by the morphology of backwaters and the flow regime, but not season. Thus, we can determine <br />whether steady flows affect water residence time in backwaters by comparing data collected during <br />other flow regimes (i.e., April and June 2008 and January 2009). The food base project will launch a <br />river trip in September 2009 to collect additional samples and water residence time measurements <br />during the steady flow experiment. <br />Links /Relationships to Other Projects <br />Data from the food base project can be used to inform results of both rainbow trout monitoring and <br />nearshore ecology projects. Although food base data collection will be focused on the Lees Ferry reach <br />with less intensive data collection at Diamond Creek, our results should still be informative to the <br />nearshore ecology project that is focused on the Little Colorado River confluence. Algae production and <br />invertebrate drift are much higher in Lees Ferry than downstream reaches. In fact, algae production at <br />downstream locations is essentially zero during times of high turbidity, and invertebrate drift <br />measurements at Diamond Creek were largely discontinued because of extremely low invertebrate <br />loads. Given the effects of the fall steady flows on food base components are likely to be subtle, we feel <br />it is prudent to concentrate our efforts on the Lees Ferry reach because the higher food base abundance <br />there makes it more likely that we will be able to detect treatment impacts. Even though food web <br />26 <br />