S MONTANA STATE LIBRARY
333.955
E30aifs
2002
3 0864 1001 9402 9
AQUATIC INVERTEBRATES AND HABITAT AT A FIXED
STATION ON THE POWDER RIVER,
CUSTER COUNTY, MONTANA
July 26, 200 1
STATE DOCUMENTS COLLECTION
MAY fl 1 2003
MONTANA ST ME LIB:'/"
1515 - - ' 'â– ""
A report to
the Montana Department of Environmental Quality
Helena, Montana
by
Wease Bollman
Rhithron Associates, Inc.
Missoula, Montana
May 2002
INTRODUCTION
This report is one of 38 brief interpretive summaries of data assembled as part of
a statewide, multi-year study conducted by the Montana Department of Environmental
Quality (MT DEQ). Each report discusses information generated from a single benthic
invertebrate sample collection and habitat evaluation at a fixed station established on a
gauged river or high-order tributary. The present treatise focuses on the aquatic
community sampled on the Powder River near the community of Locate in Custer
County, Montana on July 26, 2001 . The sample site was located by GPS reading at 46°
25' 31" N, 105° 18' 23" W. lying within the Northwestern Great Plains Ecoregion (Woods
et al. 1998). The sample was collected by personnel of MT DEQ. Sampling effort
consisted of either a composite of four Hess samples, or a one-minute kicknet collection
(Bukantis 1998). Habitat parameters were evaluated using the MT DEQ
Macro invertebrate Habitat Assessment Field Form for streams with riffle/run prevalence.
Invertebrate samples were processed and animals identified by Rhithron Associates, Inc.
Analysis of invertebrates was accomplished by applying the method recommended by
Bukantis (1998) for streams of Montana's Plains Ecoregions. The method uses a
multimetric battery to evaluate disturbance to biotic integrity. Results from the
application of other metric batteries may be found in the Appendix.
RESULTS AND DISCUSSION
Table 1 itemizes the nine evaluated habitat parameters and shows the assigned
scores for each, as well as the integrated score and condition category.
Table 1. Stream and riparian habitat assessment for a fixed station on the Powder River,
near Locate, Montana. July 2001 .
Max. possible
score
Parameter
Powder River at Locate
10
Riffle development
9
10
Benthic substrate
5
20
Embeddedness
2
20
Channel alteration
15
20
Sediment deposition
1
20
Channel flow status
18
20
Bank stability: left / right
5/5
20
Bank vegetation: left / right
9/9
20
Vegetated zone: left / right
9/9
160
Total
96
Percent of maximum
60
CONDITION*
SUB-OPTIMAL
'Condition categories: Optimal > 80% of maximum score; Sub-optimal 75 - 56%; Marginal 49 - 29%: Poor <23%.
Adapted from Plafkin et al. 1998.
Although overall habitat conditions scored sub-optimally, scores for individual
parameters suggest that instream factors potentially limit available niches for
invertebrates. Benthic substrate was rated marginal, suggesting monotonous particle
sizes. Silt and sand are implicated, since sediment deposition as well as embeddedness
was judged severe. These conditions may have been related to the marginal stability of
streambanks reported in the assessment. Notes indicate that erosion on outside banks
appeared to be natural Riparian conditions were judged optimal
Bioassessment results are given in Table 2. When this bioassessment method is
applied to these data, scores indicate that this site on the Powder River is moderately
impaired and only partially supports designated uses. However, very low abundance of
organisms in the sample (only 13 animals were collected) complicates the evaluation,
conclusions and interpretation of results are tenuous. Whether the inadequacy of the
sample was due to a depauperate community at the site or to sampling bias is not clear
from the data itself, however, the habitat assessment suggests that the nature of the
benthic substrate may limit benthic assemblages.
Table 2. Metric values, scores, and bioassessment for a fixed station on the Powder
River. The Montana DEQ bioassessment metric battery recommended for streams of
Montana's Plains ecoregions (Bukantis 1998) was used for the evaluation July 2001.
Extremely low abundance of organisms renders the score, classification, and use support
designation unreliable
Powder River at Locate
METRICS
METRIC VALUES
METRIC SCORES
Taxa richness
5
EPT richness
4
1
Biotic index
4.92
3
% Dominant taxon
46.15
1
% Collectors
100
% EPT
53.85
3
Shannon diversity
1.99
1
% Scrapers and Shredders
Predator taxa
% Multivoltine
1538
3
TOTAL SCORE
(max.=3(l)
12
PERCENT OF
MAX.
40
Impairment
classification
MODERATE
USE SUPPORT
PAR HAL
Functionally, the vast majority (85%) of animals collected in the sample were
filter-feeders, these included 2 taxa of hydropsychid caddisflies and the blackfly
Simulium sp. If the sample is representative of benthic assemblages characteristic of this
site, the abundance of this group would suggest that fine particles in suspension were
plentiful and included ample organic components Filter-feeders are expected to be
abundant in high-order streams. Turbid conditions were noted by field personnel, and
recent rains had apparently influenced flow, possibly contributing to the low abundance
of animals captured in the sample. Three of the 5 collected taxa {Fallceon quilleri,
Tricoiythodes minutus, and Cheumatopsyche sp.) prefer warm water temperatures, field
notes indicate that water temperature was measured at 24° C.
CONCLUSION
• Low abundance of organisms in the sample prohibits assessment of the site based
on invertebrate assemblages. Filter- feeders represented 85% of the animals
collected, and 3 of the 5 taxa present were warm stenotherms.
LITERATURE CITED
Bukantis. R. 1998. Rapid bioasscssnicnl macroinvcrtcbratc protocols: Sampling and sample analysis
SOP's Working draft. April 22. 1997. Montana Department of Environmental Quality. Planning
Prevention and Assistance Division. Helena. Montana.
Woods. A.J . Omernik. J. M. Nesser. J A.. Shelden. J., and Azevedo. S. H. 1999. Ecoregions of Montana
(Color poster with map. descriptive text, summary tables, and photographs): Reston. Virginia. US
Geological Survey
APPENDLX
Taxonomic data and summaries
Powder River at Locate
July 2001
Aquatic Invertebrate Taxonomic Data
Site Name: Powder River near Locate
Site ID: Y21POWDR01 7/26/01
Taxon
Approx percent of s
Quantity
nplcuscd 10
Percent
Grand Total
13
100.00
HBI
1FG
Fallceon quillen
Tricorythodes minutus
1
1
7.69
7o'J
5
4
CG
CG
Total Ephcmeroptcra
2
15.38
Chmmatopsyche sp.
Hydropsyche sp
3
2
23 OS
15.38
5
5
C i
CF
Total Trichoptera
5
38.46
Simuhum sp
'i
46 15
5
CF
Total Diptera
6
46.15
Aquatic ln>erle
Site Name: Pow
SAMPLE TOTAL
EPT abundance
TAXA RICHNESS
Number EPT taxa
Percent EPT
Site II): >21I'Q\M>RII1
DOMINANCE
TAXON
Simuiium sp
Cheumalopsychc sp
Hydropsyche sp
Fallceon quillen
Tncorylhntles minimi*
SUBTOTAL 5 DOMINANTS
ABUNDANCE PERCENT
6 46 15
3 23 08
2 15 38
1 7 69
1 7 69
13 10000
TAXONOMIC COMPOSITION
GROUP PERCENT
KTAXA ABUNDANCE
Misc Taxa
000
Odonata
000
Fphemeroptera
15 38
Plecoptera
000
Hemiptera
000
Meqaloptera
000
Tnchoptera
38 46
Lepidoplera
000
Coleopiera
000
Chironomidae 00
Hki
0% 20%
Predator
000
Parasite
...
1
Gatherer
15 38
2
Fillerer
84 62
3
Herbivore
000
Piercer
ooo
Scraper
000
Shredder
000
Xvlnphage
000
Omnrvore
000
I nknown
000
1
â– Misc Taxa
â– Odonata
f£ Kphem-Toptera
D 1'lu.uptcTa
â– Hennplera
â– Megaloptera
â– Tnchoptera
D Lcptdoptera
â– Coleoptera
""â– ' D Dipiera
D Chijonomidae
â– Predator
â– l.ii .1 ii .
69 Gatherer
â– Filterei
â– HerbtxTire
â– Piercer
D Scraper
â– Shredder
OXylophage
a Oniiivore
H I iiMi. .v.,1
TOTAL DOMINANTS
DIVERSITY
Shannon H tloge)
Shannon H Uog2)
Simpson D
VOLTIN1SM
TYPE
Multivoltine
Univoltine
Semivoltme
TAXA CHARACTERS
(fTAXA
Tolerant 2
Intolerant
Cluiger 3
REASSESSMENT INDICES
ABUNDANCE PERCENT
2 15 38
II 84 62
000
ABUNDANCE PERCENT
4 30 77
000
B-1B1 Ikarretal
METRIC
VALUE SCORE
Taxa richness
5 1
E richness
2 1
P richness
1
T richness
2 1
Long-lived
1
Sensrtive nchness
1
%toleranl
30 77 3
%predators
000 1
dinger nchness
3 1
%dommance (3)
84 62 1
TOTAL SCORE 1 2
MONTANA DEQ METRICS (Bukanlts l w 8>
METRIC VALUE Pta** Ecoregn
Taxa nchness 5
EPT nchness 4 1
Biotic Index 4 92 3
"oDominani taxon 46 15 1
%Collectors 10000
°oEPT 53 85 3
Shannon Diversity 1 99 1
%Scrapers +Shredd 00
Predator taxa
%Multivo!tine 15 38 3
%HofT 100
TOTAL SCORES 1 2
PERCENT OF MAXIMUM 40 00
IMPAIRMENT CLASS
MODERATE MODERATE SEVERE
COMMUNITY TOLERANCES
Sediment tolerant taxa
Percent sediment tolerant
Sediment sensitive taxa
Percent sediment sensitive
Metals tolerance index {McGuuei
Cold slenolherm taxa
Percent cold stenotherms
D Plains Ecoregions
â– Valleys and Foothills
D Mountain Ecoregions