8250

• UCREFRP Catalog Number: 8250
• Author: Lamarra, V. A.
• Title: Longitudinal Variation in the Trophic Structure of the Upper Colorado River.
• USFW Year: 1999.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

COLORADO RIVER
HABITAT DISTRIBUTION
300,000
_
,250,000
N 200,000
E ree rr.tc
UJ 150,000r.?
a 100,000
LL
gar .tucrtr rats
ai 50,000
rnss
0 -
1 2 3 4 5 6 7 8 9 10 11
STRATA
COLORADO RIVER
HABITAT DISTRIBUTION
40,000
30,000u
N
E s?.« rta rr.n
Lu 20,000. _?..?.
W
V _ pvf.wNQMO4tQlr"T4N
10,000 #r
M ?w. w ?ucrtr trues
riree
0
1 2 3 4 5 6 7 8 9 10 11
STRATA
Figure 31. The spatial distribution of habitat in the Colorado River during summer baseflow in 1996. Upper plate is at
full scale while the lower plate has an expanded scale to view less dense habitats.
11 had a mean density of 38.5 gm/m2 (highest value) and stratum 4 had a mean density of
10.0 gm/m2 (lowest value). As with the periphyton biomass estimates, the Gunnison River
had higher detrital densities than any stratum in the Colorado River. The final biological
parameter, macroinvertebrate biomass, also had highest Colorado River densities in the
uppermost reaches. Stratum 11 had the highest biomass levels with a mean density of 3.45
gm/m2. The densities decreased in a linear fashion to approximately 0.70 gm/m2 in stratum
8 (Figure 34). From stratum 8 through stratum 1, the macroinvertebrate densities did not
exceed l gm/m2 even though significant differences were found between adjacent stratum.
As with the other two biological parameters, the Gunnison River stratum sampled had
macroinvertebrate biomass levels equal to the highest stratum (11) in the Colorado River.
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