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130 <br />GREAT BASIN NATURALIST <br />Cleopatras <br />Couch <br />~` T2 <br />16.0 T3a _ -Tab 17.0 <br />Vol. 45, No. 1 <br />4 <br />T5 R\~ <br />Mathers <br />i Hole <br />Fig. 2. Locations of study sites at miles 16.5 and 18.0 on the Yampa River. SH represents seine haul locations. T <br />represents transect locations. <br />shorelines had been recently exposed by re- <br />duced flows (Fig. 1). Beaches within zones of <br />deposition were composed of fine sand or or- <br />ganic silt-mud deposits. Backwaters were of- <br />ten marshy with loose organic substrates. <br />At river mile 16.5 and 18.0, transects and <br />seining sites were established in areas that re- <br />fleeted the maximum number of habitat <br />types "found in the river (Table 1). Although a <br />comparison of the water depth, water veloc- <br />ity, and substrate size for these transects in- <br />dicated that Transects 1, 3, and 5 represented <br />runs or riffles of various sizes and Transects 2 <br />and 4. were indicative of deep runs or pools, <br />it was difficult to rigidly classify the habitats. <br />However, the riffle transects tended to have <br />higher average velocities and were shallower <br />in depth, whereas the run-pool transects were <br />deeper with lower velocities. <br />A comparison of the biological data in- <br />dicated the highest average chlorophyll a <br />values: (31.6 f 6.7 mg/m2} were foilnd in <br />Transect 2 and the lowest (7.8 f 5.9 mg <br />chla/m2) in Transect 4. Maximum average <br />biomasses (N = 5) of macroinvertebrates were <br />found in Transect 3 (10.8 f 4.07 gms/m2) <br />and Transect 5 (13.79 f 3.27 gmslm2) and <br />corresponded to the highest water velocities. <br />.~ <br />