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In addition, the translocated fish may experience selection forces because of the elevated levels of CO2 above Chute Falls, or other environmental factors. Water discharged from Blue Springs comes from an aquifer dominated by limestone, and contains high levels of dissolved CO2 (> 348 mg/I; Robinson et al. 1996). As this water flows toward the confluence, it passes over a series of travertine dams where release of CO2 to the atmosphere occurs, and large amounts of calcium carbonate precipitate on the river's substrates (Johnson and Sanderson 1968). The levels of free C02 progressively diminish downriver from Blue Springs, apparently being above or near the lethal limit for fish within the first kilometer, and decreasing thereafter (i.e., 196 mg/I at 17.5 km, 192 mg/I at 15 km, etc.; Robinson et al. 1996). Finally, the translocation of fish above Chute Falls may precipitate other unknown ecological effects. For example, based on visual observation, the habitat above Chute Falls is conspicuously different from that below Chute Falls (D. Van Haverbeke, pers. obs.). While algal communities exist below Chute Falls, they tend to be meager and substrates are dominated by marl, sand or gravels. In comparison, algal communities above Chute Falls are dense and diverse, often covering the substrates. Robinson et al. (1996) found that chlorophyll a biomass was significantly greater above Chute Falls. They also found that eight taxa of aquatic invertebrates were found above Chute Falls that were not found below, and that total invertebrate densities were higher above Chute Falls. In addition, densities of speckled dace above Chute Falls may be one or two orders of magnitude higher than those below Chute Falls (D. Van Haverbeke, pers. obs., D. Stone, pers. com.). Many of these differences may be because humpback chub presumably did not formerly inhabit this area, and primary production and prey were not cropped to the degree they are below the falls. The lush community above Chute Falls may be an important food source for humpback chub, particularly during flood events when components of this upriver community can be washed downriver (see Grimm and Fisher 1989, Newcombe and McDonald 1991). If food is a limiting factor in LCR, as has been suggested (Kubly and Cole 1979, Haden et al. 1999), the upstream community above Chute Falls could be important for maintaining the carrying capacity for humpback chub below Chute Falls. As Vannote et al. (1980) discussed, downstream communities are fashioned to capitalize on upstream processing inefficiencies. The main question that needs to be asked is whether or not establishment of a small breeding population (likely well below minimum viable population standards) has any potential to detrimentally affect the population of humpback chub below the falls. In particular, we ask if there is potential to: 1) increase the proportion of inbred fish into the main LCR population (i.e., increase the inbreeding coefficient), and 2) decrease the Ne of the main LCR population (see Ryman and Laikre 1991, Wang and Ryman 2001). Inbreeding in an infinitely large population is defined as the mating of individuals that are more closely related to each other than individuals mating at random within a population. All populations experience some level of inbreeding (Kincaid 1983). In order to measure the increased level of inbreeding that could potentially occur in a translocation procedure, it is first necessary to know the base-level inbreeding 38