By Leah Ritz
Ames, Iowa
Environmental Studies, Geography
Even many locals don’t know that the
St. Croix River, on the border between
Minnesota and Wisconsin, was one of the
first rivers designated by the Wild and
Scenic Rivers Act of 1968 and is, consequently,
one of the best preserved river
systems in the upper Midwest. Professor
Dan Hornbach from Macalester’s Biology
and Environmental Studies Departments
has been researching native mussel
populations in the St. Croix for almost
two decades.
Mussels are important in river communities
because they may help stabilize
river substrate (base) and are important
indicators of river health. The St. Croix’s
designation as a pristine habitat makes it
one of the best environments for mussels
in the Midwest, and it has a very diverse
population of native mussels including two
species of mussels federally designated
as endangered—the winged mapleleaf,
and Higgins eye—as well as several
other threatened species that have been
destroyed in other locations throughout
the country.
In addition to a long-term monitoring
project, there are numerous short-term
projects relating to the overall theme of
river and mussel health. Last summer’s
research began a three-year project to
determine changes in the dynamics of the
river with regard to changes in the riverbed
substrate and sediment transport.
Our studies
provide important
information to
the National Park Service ... about how best
to manage the St.
Croix River and surrounding areas.
— Leah Ritz ’09 The St. Croix is under constant pressure
from numerous natural and man-made
stressors, in particular the St. Croix dam
and changing land use around the basin.
These two factors alone can significantly
alter the river’s flow and all dependent
habitats. These studies provide important
information to the National Park Service
and the Departments
of Natural Resources
in both Minnesota and
Wisconsin, helping
them determine how
best to manage the St.
Croix and surrounding
areas. Macalester faculty
and students play
an integral role in monitoring
and maintaining
mussel populations and
ensuring the longevity
of one of the Midwest’s
best-preserved rivers.
The original mussel monitoring project
has evolved into a much larger project
involving faculty from many departments
conducting research on a local level.
The project currently involves biologists
interested in the ecology and genetics
of mussels, a professor in the Geology
Department looking at hydrology, geographers
mapping changes in land use in
surrounding areas, and historians developing
a timeline of the hydroelectric dam just
above Taylors Falls on the St. Croix. This
project, begun in 1990, has continued to
grow and now truly highlights the interdisciplinary
nature of field work in environmental
studies and conservation.
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