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<br />Introduction <br /> <br />A recent evaluation of the Upper Colorado River Fishes Recovery Program (Stanford <br />1994) concluded that a standardized sampling program for monitoring aquatic invertebrates <br />should be implemented. Primary issues outlined by Stanford were the lack of information on <br />the distribution and abundance patterns of zoobenthos communities, the need to identify <br />invertebrate taxa and habitat types with a strong dependence on flow characteristics, and the <br />need to develop rapid assays to detect if invertebrate production might be limiting endangered <br />fish populations. <br /> <br />An understanding of where and why changes in invertebrate communities occur will <br />improve our ability to predict how downstream invertebrate communities may change in f <br />relation to the hydrologic regime. We also need to evaluate inter-habitat variation in <br />invertebrate populations. Certain habitats, e.g., backwaters, are thought to support higher <br />production of invertebrates (zoobenthos and zooplankton) than others, e.g., main channel <br />runs (Stanford 1994). Different habitat types are also thought to exhibit variable sensitivity <br />to discharge (Stanford 1994). <br /> <br />The design and implementation of a monitoring program should be an iterative process. <br />Sampling locations and methods should be added, removed, or modified as results are <br />evaluated annually. The sampling program outlined here should be viewed more as a starting <br />point rather than as long-term protocols. The initial emphasis of the project should be to <br />delineate sampling locations and describe both the inter- and intrahabitat variability of <br />invertebrate communities within and among sampling reaches. This initial data from this <br />project will allow us to design a custom fit sampling program for individual reaches and <br />habitats and will result in a better final monitoring project. Ultimately the key to m~ng this <br />monitoring project useful and cost-effective will be in defining a reasonable set of key habitat <br />types and reaches to sample. In this proposal, I have described field, laboratory, and office <br />procedures that will allow us to delineate invertebrate assemblages and better understand <br />their response to changing hydrologic regimes. <br /> <br />Objectives <br /> <br />The listed objectives are designed to describe current macroinvertebrate assemblages and <br />assess the effects of future conditions on these assemblages. <br /> <br />Objective 1. Determine longitudinal patterns in benthic macroinvertebrate communities. <br /> <br />Objective 2. Identify habitat specific aquatic macroinvertebrate taxa that can be used as <br />indicators of quality habitat. <br />