9505

• UCREFRP Catalog Number: 9505
• Author: Cooper, D. J. and C. Severn.
• Title: Wetlands of the Escalante State Wildlife Area on the Gunnison River, Near Delta, Colorado
• USFW Year: 1994.
• USFW - Doc Type: Hydrology, Water Chemistry, Vegetation, Invertebrate Communities, and Restoration Potential.
• Copyright Material: NO

Benthic chironomids and other invertebrates (including
Gastropoda, Nematoda, Odonata, Hemiptera, Culicidae,
Ephemeroptera, and Coleoptera) were present in all communities
(Figure 23). Greatest densities of chironomids and other
invertebrates occurred in the bulrush community. chironomids
were the dominant group in all communities exceeding by many
times the densities of other invertebrates. Benthic invertebrate
densities were greater than water column invertebrates in all
communities and the data presented in Figure 23 again shows the
importance of benthic chironomids to invertebrate biomass
production.
Water column and benthic invertebrate densities for each
community station are presented in Figure 24. Backwater station
CE2 had the highest mean density of water column invertebrates of
all stations with 63 L-1. This station was sampled only on the
first two sample periods and was dry the remainder of the season.
Station CE10, an open water community in an oxbow also had high
densities with 47 L-1 and was sampled all six periods. Season
means for bulrush and river stations ranged between 2 and 7, and
0.02 and 0.18 (not apparent due to graph scale) organisms L-1,
respectively.
Benthic invertebrates had the highest densities at station
CE16 in the bulrush community with 176 organisms L-1. This
station was not sampled after 28 July as a flash flood disrupted
the bulrush sample stand. Station CE20 in the open water and
CE21 in the backwater community also had relatively high
densities over the season with 114 and 99 organisms L'1,
respectively. Both of these stations were sampled on all six
periods. No benthic invertebrates were found in samples at
bulrush station CE8 which was sampled only on the first three
periods. The range for benthic invertebrate densities at the
river stations was between 7 and 40 organisms L'1.
Of all the stations sampled only stations CE11 (open water)
and CE2 (backwater) had mean season densities of water column
invertebrates that were greater than benthic invertebrates.
Also, differences between benthic and water column invertebrates
densities were generally much greater between backwater and river
stations than the bulrush and open water stations. Variability
of invertebrate densities of both strata between stations in
similar communities is also evident by the data presented.
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