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

The macroinvertebrate biomass levels in the Gunnison River were generally not significantly
different from those in the Colorado for both riffles and runs with the exception of the fall
1995 densities. In both habitat types, the Gunnison had significantly higher invertebrate
biomass levels.
COLORADO RIVER-RIFFLES COLORADO RIVER-RUNS
Mean Detritus Mean Detritus
100 100
....- _ ._.... ......... ........

BO
_..
...........
-- ;... ..........._.

so

......
?0 .. ..._
-
70
...
......

5
d 40 ..
40 .._. .... _..
..... _....
....
30

.. .
c
30 .. ...
20 ... ._

10
.. _ ..
10 Z-
0
Spring 1994 Fall 1994 Spring 1995 Fall 1995 Spring 1994 Fall 1994 Spring 1995 Fad 1905
PERIOD PERIOD
Figure 25. The seasonal distribution of detritus for riffles and runs in the Colorado River (above) and the Gunnison River
(below).
COLORADO RIVER-RIFFLES COLORADO RIVER-RUNS

100 Mean Invertebrate Dry Weight Mean Invertebrate Dry Weight
100

u 1° F 10
o
o

1 1

• _.. T
._
0
Spring 1994 Fag 1994 Spring 7905 Fall 1995 ° Spring 1994 Fall 1994 Sprang 1995 Fall 1995
PERIOD PERIOD

GUNNISON RIVER-RIFFLES GUNNISON RIVER-RUNS

100 Mean Invertebrate Dry Weight
0 Mean Invertebrate Dry Weight
10

2 10 - 10
?
O •

e
f
°
Spring 1994 Fall 1994 Spring 1995 Fall 1995 0 - Spring 1994 Fall 1994 Spring 1995 Fall 1995
PERIOD PERIOD
Figure 26. The seasonal distribution of invertebrate dry weight for riffles and runs in the Colorado River (above) and the
Gunnison River (below).
25