1. Mussel distribution and community structure in the Mukwonago River
Acknowledgments
We thank Carroll University’s Pioneer Scholar program for funding our research. We
thank several people who have shared their time and expertise: Dr. Sue Lewis, Dr. Kerri
Wrinn, Dr. Jason Freund, Lisie Kitchel, Sue Roskopf, Allison Sedmak, Aubrey Ellickson,
Bjorn Lewis, Erin Cox, Gina Finnel, Glen Cox, Ian Anderson, Mackenzie Griffin, and Tim
Musial. Without them this research could not have been accomplished.
Discussion and Conclusions
Community Composition
•In the CPUE survey we sampled a total of 12,309 mussels and in the quadrat survey we
sampled 1,093.
•Both methods identified similar dominant species
CPUE surveys were biased towards P. sintoxia and E. dilatata
Quadrat surveys found similar percent composition of P. sintoxia, E. dilatata and V.
ellipsiformis
V. ellipsiformis is a smaller species, making it less noticeable
•Both the species richness and abundance increased with distance from the Fox River.
•Some species were only found at upstream sites
Villosa Iris, Strophitus undulatus, Dreissena polymorpha, and Venustaconcha
ellipsiformins
•Some species were only found at downstream sites
Quadrula pustulosa is typical of larger rivers and is generally only found downstream;
Quadrula pustulosa use catfish as hosts.
•V. iris was not found downstream, but became increasingly frequent at upstream sites.
State endangered & endangered in Canada
At the edges of its range in Wisconsin
•L. cardium occurs at low densities throughout the river.
•D. polymorpha occur in much higher densities near the phantom Lake dam, so too do
important native mussels, such as V. iris.
This is likely because the D. polymorpha are washed downstream from the lentic,
rocky habitats while V. iris likely excyst from fishes that move upstream and
eventually accumulate downstream of the dam.
This suggests that the dam may play a vital role in the distribution of these species.
The juxtaposition of invasive and conservation-relevant species is a concern.
Future Research:
Although this portion of the Mukwonago River has the most diverse bivalve community
described in this system, surveys of the rest of the the Mukwonago River would be
beneficial.
We will explore additional habitat metrics in relation to both the full mussel community
and individual species.
Nearby tributaries of the Fox River should be surveyed to determine whether other
strong, but undocumented and therefore unprotected mussel communities exist in this
region.
Introduction
● North America possesses the highest species richness of freshwater mussels globally
and, in Wisconsin alone, there are 51 native species of mussels.
● The Mukwonago River in southeastern Wisconsin has several different types of habitat
within a relatively short stretch of the stream.
● The Mukwonago River is relatively diverse compared to other streams in southeastern
Wisconsin with a community of 15 documented species.
● The Mukwonago is also home to several state threatened and endangered species of
mussels and fishes.
● The mussels of the Mukwonago River offer an opportunity to better understand how
and why this area supports this uniquely rich and diverse community.
Matt Baumann, Lynne Noel, Roberto Brenes, Todd Levine
Department of Life Sciences, Carroll University, 100 North East Avenue, Waukesha, WI 53186
References
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Results
Figure 3. Total number of each mussel that constituted more than 1% of the total community. The total number
of most species and the total number increased with distance upstream from the confluence with the Fox River.
Figure 4. Total number of each mussel that constituted more
than 1% of the total community. The total number of most
species and the total number increased with distance upstream
from the confluence with the Fox River. (above)
CPUE: Community Composition
Quadrat: Community Composition
Species Habitat Associations
Specific Research Objectives
1. Assess patterns of bivalve species richness and abundance within the river
2. To determine how the bivalve community varies throughout.
Figure 5. Total mussel density increased with
increasing proportion of gravel at each of the sites.
(above left)
Figure 6. Total mussel density decreased with
increasing depth at each of the sites. (above right)
Figure 7. Total unionid mussel density is higher in
the presence of invasive species. (right)
CPUE
12,309 total mussels
Pleurobema sintoxia 44.1%
Elliptio dilatata 30.4%
Venustaconcha ellipsiformis 9.3%
Dreissena polymorpha 6.1%
Lampsilis cardium 3.8%
Strophitus undulatus 2.6%
Other bivalve species: Actinonaias ligamentina,
Amblema plicata, Corbicula fluminea, Lampsilis
siliquoidea, Quadrula pustulosa
QUADRAT
1,093 total mussels recovered
Pleurobema sintoxia 28%
Venustaconcha ellipsiformis 25%
Elliptio dilatata 23%
Lampsilis cardium 9%
Dreissena polymorpha 5%
Actinonaias ligamentina 4%
Corbicula fluminea 2%
Strophitus undulatus 2%
Other bivalve species: Lampsilis siliquoidea,
Pyganodon grandis, Lasmigona complanata,
Quadrula pustulosa, Vilosa iris
Methods
● Two types of surveys were conducted throughout the summer from early May to late
August.
● We conducted a catch per unit effort (CPUE) survey which was a timed, qualitative
search of 34 sites in the Mukwonago River equally spaced from the Phantom Lake Dam
to the confluence with the Fox River.
● The second survey employed quadrat sampling, a quantitative method of assessing the
density of bivalves at a scale of 0.25 m2.
● We conducted quadrat sampling at 10 sites, within which we placed three grids each
and sampled a minimum of 10 quadrats per grid.
Figure 1. Quadrat sampling pattern, showing relationship between sites, grids
and quadrats. Note that quadrats are not to scale. (above left)
Figure 2. Example of sorted mussels from one site. (above right)
Figure 3. Portion of the
Mukwonago River surveyed from
the Fox River to the Phantom Lake
dam. (right)
p < 0.001
r2 = 0.36
p < 0.001
r2 = 0.06
p < 0.001