Katherine Anne Glover, Lauren Joca, Jeff Kirchberg, and Grace Saunders
Group Project in Advanced Conservation Biology (Bio 222- Dr. Evans)
Introduction
Methods
On the Cumberland Plateau near Sewanee, TN, a species of
aquatic plant, Brasenia schreberi, is threatening to impede
the navigability of Lake Dimmick by the Sewanee Crew
Team.
Conclusions
In order to assess the feasibility and efficacy of grass carp
in controlling the Brasenia schreberi population, our study
will involve creating 4 types of testing areas. There will be
3 plots for each of the 4 testing areas, ultimately
composing 12 enclosed areas within Lake Dimmick. The 4
testing areas include: carp alone, no carp, carp in addition
to other aquatic plants, and no carp and no other aquatic
plants. All of the testing areas will have the water shield
enclosed within the plot. The depth of Lake Dimmick in
these areas will serve as a constant. Furthermore, In effort
to better our understanding of the physical layout of Lake
Dimmick, we plan to create a baseline GIS map of the
area. This step will benefit future management of the lake
by beginning a continual account of Dimmick’s gradual
Brasenia composition following the implementation of a
management plan.
© File copyright
Research suggests that the effective population size of grass
carp, without negative effects of overexploitation by fish
species, is 62 individuals per hectare (van Dyke et al., 1984)
or two fish per metric ton of biomass (Leslie et al., 1987).
Previous research has not shown that carp feed on the
specific aquatic species present in Lake Dimmick
preferentially to Brasenia schreberi, however it does show
that species from genus Utricularia sp. and Eleocharis sp.
are favored.
Multiple benefits of introducing grass carp:
+Proven to ingest Brasenia schreberi (van Dyke et
al., 1984)
+Not a threat to invading other aquatic areas
+Use of herbicide will decrease
+Cost effective (Shireman et al., 1986)
+No threat of overpopulation because the carp are
triploid, sterile
Multiple costs of introducing grass carp:
-Do not preferentially consume Brasenia schreberi
(Pauley et al., 1994)
-Carp can eliminate all biodiversity within an ecosystem
if population becomes too large (Leslie et al., 1987)
-Will require strict monitoring of population size so that
groups introduced later will not result in too large of a
population
-Threat of bioaccumulation if fish are exposed to
herbicide and later predated
The two conflicts of interest:
1. Use of Lake Dimmick for recreational use
2. Use of Lake Dimmick as a secondary water supply
The concerns with current management practices:
1. Requires that the native Brasenia cover is reduced for
crew purposes
2. Health effects from use of herbicides
What we propose as a sustainable solution:
1. Introduce grass carp into Lake Dimmick as a natural
means of biological control
2. Test the efficacy of grass carp with reducing Brasenia
cover
Our anticipated results:
1. The introductioon of grass carp will result in the
diminishing of the Brasenia population
2. The decline of Brasenia will be inhibited by the presence
of additional aquatic species
Overall, this project addresses what is truly invasive in the
biological control of a native species, by an invasive species,
in a non-native habitat.
Colin Purrington. You may
use for making your poster, of course, but
Figure 2: An example of enclosures
please do not plagiarize, adapt, or put on
your own site. Also, do not upload this file,
even if modified, to third-party file-sharing
sites such as doctoc.com.
If you
Expected Results
Family
Scientific
Namehave
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Carex glaucescensonto
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of
Carex longii
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present,
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and for grass carp to exhibit preferential eating when
Cyperaceae
Carex louisianica Bailey
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water shield and other aquatic plants are present. When
Cyperaceae
Dulichium arundinaceum (L.) Britt.
only in the presence of water shield, then grasshttp://colinpurrington.com/tips/academic/pos
carp will
Cyperaceae
Eleocharis microcarpa Torr. var. filiculmis Torr.
consume most if not all of the water shield. When
in the
terdesign.
Cyperaceae
Eleocharis obtusa (Willd.) J.A. Schultes
presence of water shield and other aquatic plants, grass
carp will mostly, if not exclusively, consume aquatic plants
that are more preferential than water shield.
Figure 1: A map highlighting Brasenia schreberi cover in Lake Dimmick, Sewanee, TN
Figure 3. Percent of Brasenia is expected to decrease with the
introduction of carp, but at a slower rate in the presence of other
aquatic plant species.
Cyperaceae
Common Name
Southern waxy sedge
Long’s sedge
Louisiana sedge
Three-way sedge
Spikerush
Blunt Spikerush
Square-stem spikerush
Cyperaceae
Eleocharis quadrangulata (Michx.) Roemer & J.A.
Schultes
Rhynchospora capitellata (Michx.) Vahl
Cyperaceae
Rhynchospora glomerata (L.) Vahl
Clustered beaksedge
Cyperaceae
Schoenoplectus purshianus (Fern.) M.T. Strong
Weakstalk bulrush
Juncaceae
Juncus canadensis J. Gay ex Laharpe
Canadian rush
Juncaceae
Juncus debilis Gray
Weak rush
Brownish beaksedge
Juncaceae
Juncus longii Fern.
Long’s rush
Juncaceae
Juncus repens Michx.
Lesser creeping rush
Lentibulariacea Utricularia gibba L.
e
Orchidaceae
Platanthera clavellata (Michx.) Luer
Humped bladderwort
Poaceae
Calamagrostis cinnoides W. Bartram, nom. illeg.
Nuttall’s reed grass
Sparganiaceae
Sparganium americanum Nutt.
American bur-reed
Xyridaceae
Xyris torta Sm.
Yellow-eyed grass
Cabombaceae
Brasenia schreberi J.F. Gmel.
Watershield
Literature cited
Leslie Jr, A. J., Dyke, J. M. V., Hestand III, R. S., & Thompson, B. Z. (1987). Management of
aquatic plants in multi-use lakes with grass carp (Ctenopharyngodon idella). Lake and
reservoir management, 3(1), 266-276.
Pauley, G. B., Thomas, G. L., Bonar, S. A., Frodge, J. D., Marino, D. A., Thiesfeld, S. L., ... &
Sehgal, H. (1994). An Overview of the Use and Efficacy of Triploid Grass Carp
Ctenopharyngodon idella as a Biological Control of Aquatic Macrophytes in Oregon and
Washington State Lakes1. March 7~ 95 1994 Gainesville, Florida, 52.
Shireman, J. V., Colle, D. E., & Canfield, D. E. (1986). EFFICACY AND COST OF AQUATIC WEED
CONTROL IN SMALL PONDS'. JAWRA Journal of the American Water Resources
Association, 22(1), 43-48.
van Dyke, J. M., Leslie Jr, A. J., & Nall, J. E. (1984). The effects of the grass carp on the aquatic
macrophytes of four Florida lakes. Journal of aquatic plant management, 22, 87-95.
Small green wood orchid
Table 1: Obligate wetland species found in Lake Dimmick
Acknowledgments
We thank Nate Wilson for all of his help in informing us on
the biology of Lake Dimmick. We also thank Dr. Jonathan
Evans for his advising in the development of this project.