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<br />16 <br /> <br />suggestions into the development of monitoring programs for these resources, As a're~ult of <br />recommendations, an effective mark-recapture program in the LCR and different stock <br />assessment models for assessing the status and trends ofthe humpback chub have been <br />developed, However, review findings on the aquatic food base program were insufficient <br />because current understanding about linkages between lower trophic levels and food availability <br />offish were deemed inadequate to interpret foodbase in relation to management goals, They <br />identi fied that further research was needed before a long-term monitoring program existed, <br />because assumed linkages between foodbase and fishes had not been empirically established. <br /> <br />Foodbase Resources <br />The aquatic protocol evaluation panel had concerns with the lack of empirically <br />established linkages between food base and fishes (Bradford et aI., 2001), and identified that a <br />possible consequence of the recent increase in primary and secondary production may <br />differentially benefit non-native species (competitors or predators) over native species, Because <br />of this, additional research and the restructuring of the existing foodbase monitoring program is <br />warranted in light of its importance toward meeting stakeholder objectives, For this reason, a <br />refocusing of the monitoring and research efforts is to be undertaken toward assessing whether <br />primary production is actually limiting the abundance and structure of the downstream fish <br />community directly or indirectly through abiotic and biotic interactions, <br />A series of integrated studies will address a number of issues identified by the aquatic <br />protocol evaluation panel (Bradford 2001), Primary focus is on the research and development of <br />an organic budget and foodweb linkage program as an organizational framework to determine <br />whether or not the aquatic foodbase is limiting, and to determine what organic sources, and <br />where limitations occur within the Colorado River system. This requires multiple approaches: I) <br />continuation of the conventional phyto-benthic and invertebrate monitoring, focused initially in <br />the Lees Ferry section; conduct in-stream metabolism and community respiration experiments; <br />3) quantify organic and inorganic carbon supply and fluxes (decomposition, transformations and <br />residency); 4) based on findings of the organic mass balance research design and effective <br />sampling program having the appropriate sampling locations, methods and frequency for <br />assessing and quantifying organic flux (sources, pools, transformations and movement), and 5) <br /> <br />GCMRC FY2005-2006 Draft Annual Work Plan (November 10,2003) <br />