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<br />I <br /> " <br />I :to <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> -. <br /> <br />10 <br /> <br />Furthermore, the pattern of over-bank flow during high discharge events was highly <br /> <br /> <br />variable for the river longitudinally. Areas near Parker, AZ. had bankfull discharges near <br /> <br /> <br />seasonally with the river increasing from 100 m in width at low flow to greater than 400 <br /> <br /> <br />m before achieving bankfull status (USDA, river stage data 1900-1929, Reclamation <br /> <br /> <br />Library Records). Shifting sand bottoms heavily shaded by turbidity ~ould have had <br /> <br /> <br />greatly reduced productivity. River fringes, flooded oxbows, eddy return-channels, and <br /> <br /> <br />other wetted depressions on the floodplain remained productive and served as nurseries <br /> <br />for young fish. Their effectiveness in contributing to larval/juvenile survival depended on <br /> <br /> <br />water fluctuations filling them followed by discharges sufficient to maintain habitat, then <br /> <br /> <br />high enough at a later time to allow juveniles back into the channel (Welcomme 1985; <br /> <br /> <br />Walker et al. 1995). After colonization by marsh-adapted plants, off-channel habitats <br /> <br /> <br />also acted as points of input for organic material, which, with organic transport from the <br /> <br /> <br />watershed (albeit meager; see, however, Lieberman and Burke 1991; Rinne and <br /> <br /> <br />Minckley 1991; Lieberman and Burke 1993), provided detritus when primary producers <br /> <br /> <br />were suppressed. <br /> <br /> <br />Ten fish species occupied this unpredictable environment, three marine (one <br /> <br />common, two rare) that entered from the Gulf of California and seven freshwater (three <br /> <br /> <br />common, four rare) (Minckley 1973) (Table 1). Each of the three common freshwater <br /> <br /> <br />species, razorback sucker (Xyrauchen texanus), bonytail (Gila elegans) , and Colorado <br /> <br />squawfish (Ptychocheilus lucius), is large-bodied, long-lived, practices cyclic (seasonal) <br /> <br /> <br />reproduction, and has long generation times, large clutches, and small investment in each <br /> <br />offspring (see chapters 13, 17, 19 in Minckley and Deacon 1991). <br />