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 4.-The percentage of <25-µm-size-fraction chlorophyll a and >25-µm-size-fraction
chlorophyll a concentration for phase 1 (Oct. 1986 through June 1987).
Chlorophyll Samplin g date
Station size-fraction 10/2012/01 1/05 2/09 3/16 4/20 5/18 6/22
µm Percent
Davis Dam <25 84 100 100 82 81 100 93 100
>25 16 0 0 18 19 0 7 0
Park Moabi <25 85 99 80 88 80 82 79 82
>25 15 1 20 12 20 18 21 18
.
Parker Dam <25 100 95 100 99 76 100 81 100
>25 0 5 0 1 24 0 19 0
Headgate Rock Dam <25 87 100 94 79 99 87 47 84
>25 13 0 6 21 1 13 53 16
Palo Verde Diversion Dam <25 100 100 97 100 72 100 80 100
>25 0 0 3 0 28 0 20 0
Cibola <25 100 86 100 60 100 78 87 84
>25 0 14 0 40 0 22 13 16
Imperial Dam <25 97 98 100 74 73 71 100 89
>25 3 2 0 26 27 29 0 11
Yuma <25 98 77 100 73 100 100 100 88
>25 2 23 0 27 0 0 0 12
Table 5.-F-test results based on ANOVA
between all stations and mean total
chlorophyll a concentration for phase 1 (Oct.
1986 through June 1987).
Chlorophylla Station
mg/m3 Tukey
grouping
3.03 Yuma X
2.16 Imperial Dam B
1.50 Davis Dam C
1.43 Park Moabi C
1.36 Cibola C
1.30 Parker Dam C
1.19 Headgate Rock Dam C
0.91 Palo Verde Diversion Dam C
Means with the same letter are not significantly
different at the 0.05 confidence level.
net and into the subnet size-fraction. This method
also caused the subnet size phytoplankton to become
caught in the net on occasion, as a consequence,
some of the species collected were identified in both
the <25-µm and >25-µm size-fractions. Number of
species collected in each phytoplankton group at
each station are listed in table 6. During phase 1,
chlorophyll a was used as an index of phytoplankton
biomass for the <25-µm size-fraction. Because the
<25-µm size-fraction comprised the greatest
proportion of total chlorophyll a, it was concluded
that this size-fraction also made up the greatest
proportion of total phytoplankton. For the <25-µm
and >25-µm size-fractions, pennate diatoms com-
prised the dominant phytoplankton group (order
Pennales). Following this group in decreasing order
were:
correlation was performed between <25-µm phyto-
plankton and <25-µm POM to determine if a
relationship exists between the two variables. The
correlation was insignificant (p>0.05), which
indicates that nonchlorophyll bearing particles or
detrital material comprised the greatest proportion
of POM in the river. Chlorophyll a concentrations
are reported in table 16A.
Phytoplankton.-A complete phytoplankton species
list for all stations is reported in table 17A.
Phytoplankton species-totaling 242-were identi-
fied from upstream to downstream sampling
stations. Phytoplankton were collected using a pump
that at times forced net-size plankton through the
- Chlorophyta (green algae)
- Cyanophyta (blue-green algae)
- Euglenophyta (euglenoids)
- Chrysophyta (yellow-brown algae)
- Pyrrhophyta (dinoflagellates)
- Rhodophyta (red algae)
The concentration of the >25-µm size-fraction
phytoplankton was generally less than 100 cells per
liter from Davis Dam downstream to Yuma. Many
of the 121 phytoplankton species collected in Davis
Dam tailwater were received from the reservoir. By
contrast, 180 phytoplankton species-predomi-
nantly diatoms-were collected at Havasu Delta.
There were 152 phytoplankton species collected at
9