7993

• UCREFRP Catalog Number: 7993
• Author: Mabey, L. W.
• Title: Planktonic and Benthic Microcrustaceans from Floodplain and River Habitats of the Ouray Refuge on the Green, River, Utah - Master's Thesis.
• USFW Year: 1993.
• USFW - Doc Type: Brigham Young University,
• Copyright Material: NO

Harpacticoida
One copepod group absent from much of this study is the harpacticoids. Densities
of 200-10,200/m2 in Lake Michigan have been reported by Nalepa and Quigley
(1983). Shiozawa (1991) reported densities of up to 100,000/m2 in Minnesota streams,
but also found that harpacticoids preferred gravel, not shifting sand substrates, such as
are found in the Green River. Adult specimens of Canthocamntus staphvliT_noides were
collected in the floodplain with densities ranging from 158-2,106/m2. Two adult
specimens of Nannopus spp. were sampled in the Ouray backwater plankton (7/m3)
and an unidentified species was collected in the backwater benthos at a density of
359/m2. No harpacticoids were collected in the river. The harpacticoid densities
reported in this study are low and are most similar to Lake Michigan densities.
Implications
High densities of microcrustaceans in floodplain plankton have been reported
before. This study gave evidence of the additional importance of the benthos as a
source of microcrustaceans in backwaters, river channels, and especially floodplains.
The benthic densities at times were greater than the plankton densities.
Most of the large rivers in the U.S. have been dammed to provide hydroelectric
power, flood control, or water for irrigation. These dams have caused many changes
downstream, including temperature, turbidity, sediment transport, and flood regimes.
The Green River is no exception. Development of the Flaming Gorge Dam has
changed the hydrological profile of the river downstream. Concomitant with that- has
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