8132

• UCREFRP Catalog Number: 8132
• Author: Lieberman, D. and T. Burke.
• Title: Limnology and Drift of Particulate Organic Matter Through the Lower Colorado River.
• USFW Year: 1991.
• USFW - Doc Type: Denver, CO.
• Copyright Material: NO

Table 7.-Zooplankton species collected from all stations in the lower Colorado River (Oct. 1986 through Aug. 1988).
Davis Park Havasu Parker Headgate Palo Verde Cibola Palo Verde DR3 Imperial All Laguna Yuma
Taxa Dam Moabi Delta Dam Rock Diversion Irrigation Dam American
Dam Dam Drain Canal
Copepoda
Calanoida spp. X x x x x x x x x
Eurytemora affinis x x
Cyclopoida
Cyclops spp. X x x x x x x
Diacyclops bicus-
pidatus thomasi x x x x x x x
Ectocyclops sp. X x x x x
Mesocyclops edax x x x
Harpacticoida x x x x x x x x
Nauplius x x x x x x x x x x x
Copepodid x x x x x x x x x x
Cladocera
Bosmina sp. X x x x x x x x x x x
Ceriodaphnia sp. X x
Daphnia spp. X x x x x x x x x x x
Leptodora kindtii x x x
Rotatoria
Asplanchna sp. X x x x
Brachionus sp. X x x
Hexarthra sp. X
Kellicottia sp. X x
Keratella sp. X x x x x x x x x
Lecane sp. X x
Ploesoma sp. X x
Polyarthra sp. X x x x x x x x
Ptygura sp. X
Synchaeta sp. X x
Unidentified
r t'f
o f er species x x x x x
Total species 21 16 10 16 14
concentrations decreased from upstream to down-
stream (tables 34A through 41A). Rotifer concen-
trations often exceeded copepod and cladoceran
concentrations for all sampling dates and stations.
Cladocerans and rotifers comprised the greatest
percentage of total zooplankton. Copepods disap-
peared rapidly in the river below the dams.
Chironomid larvae and oligochaetes were collected
occasionally in the plankton nets at Park Moabi and
Parker Dam. Mayflies were collected from Park
Moabi and the Cibola station. Water bears
(Tardigrada) also were found at Palo Verde Diversion
Dam and at Imperial Dam.
Particulate Organic Matter
Phase 1 objective was to determine the quantity,
distribution, and composition of particulate organic
matter by sieving known volumes of water through
various nets and filters. Figure 4 graphically depicts
the quantities (mean concentrations) and distribution
of the various size fractions of POM collected during
x x x x x x x x
13 9 3 8 12 4 6 7
phase 1 for all stations sampled. A number of obser-
vations can be gleaned from this figure. A general
observation is that the concentration of total POM
(all sizes combined) seemed to be much greater
downstream of Palo Verde Diversion Dam. Also, the
majority of the POM was fine material which had
passed through a 25-µm mesh net. From upstream
to downstream stations, the <25-µm POM comprised
64 to 92 percent of total POM. Mean concentrations
of the <25-µm POM, g/m3 were:
- Davis Dam (upstream) ...... 0.73
- Park Moabi ................. .66
- Parker Dam ................ .82
- Headgate Rock Dam ........ .65
- Palo Verde Diversion Dam ... .87
- Cibola ..................... 1.39
- Imperial Dam .............. 1.40
- Yuma ...................... 2.42
The concentration of the <25-µm organic material
was significantly greater (p<0.05 ANOVA) at Yuma
than all other upstream stations (table 8).
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