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

habitats had standing water and were sampled. These are: (1)
submersed aquatic marsh dominated by sago pondweed (Potamogeton
pectinatus); (2) hardstem.bulrush (Schoenoplectus acutus) and
broadleaf cattail (Typha latifolia) emergent marsh; (3) riverine
backwaters which were unvegetated; (4) river channel which was
unvegetated. Other important vegetation types on site include
cottonwood forests, tamarisk thickets, and saltgrass meadows.
These later habitats were not sampled for invertebrates because
they never had standing water during the sample period and could
not provide habitat for fishes, although leaf litter from these
stands could certainly be an important component of the aquatic
food chain for certain stands. For the two marsh types occurring
in the Escalante State Wildlife Area wetlands, the production of
autochthonous organic matter for the aquatic food chain was high.
Invertebrates were sampled in the water column and benthos
for all stations at all sample dates. A ni.tex covered net, 15 cm
in diameter, and 182 cm2 in area, with long handle was carefully
lowered to the bottom of the water column and allowed to sit for
approximately one minute. Then, the net was raised vertically in
one very rapid motion and all invertebrates collected in the net
were washed using tap water into plastic collection bottles.
Formalin was added to .each bottle to preserve the organisms.
Three water column invertebrate samples were collected from each
sample station for each sample date. Water depth was measured
for each sample and the depth was multiplied by the sample net
area to determine the volume of water sampled.
Benthic samples were collected with a piston core sampler
which was 29 cm2 in area. Samples included only the top 2 cm of
sediment, making each sample 58 cm3 by volume. Only one sample
was collected from each station on each sample date because we
thought that picking invertebrates from this mud would be
extremely labor intensive. However, the sediments proved to be
largely of coarse-textured material which could be sorted with
sieves. All data for all parameters sampled are summarized here
and the data presented in appendices.
No quantitative vegetation data was collected because of
time constraints. This information would have added somewhat to
our analysis of landscape patterns in the study area, but we did
not feel it would be a critical component to evaluating the
capability for supporting fishes.
One of our study goals was to determine how the Gunnison
River wetlands function today, and how they may have functioned
in the past. By function we mean its present and past hydrologic
regime, flood characteristics, sediment movement, water quality,
vegetation,-and habitat for fishes and other wild animals. In
general, this site has undergone less changes than the other
sites investigated. Only a portion of the site has been diked
off and flooding occurred over islands and terraces during 1993.
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