THE STATUS OF NATIVE AQUATIC VEGETATION AND EURASIAN
WATER MILFOIL (Myriophyllum spicatum L.) IN SELECT NAVIGATION
POOLS OF THE UPPER MISSISSIPPI RIVER.

Jenny Winkelman
Minnesota Department of Natural Resources, Long Term Resource Monitoring
Program 
1801 South Oak St., Lake City, MN  55041

Little is known about submersed aquatic plants and the status of exotic species,
namely Eurasian water milfoil (Myriophyllum spicatum L.), in the Upper
Mississippi River (UMR).  In 1996, the Minnesota Department of Natural
Resources' Natural Heritage and Nongame Research Program and the Exotics
Species Program co-funded expanded vegetation surveys in Navigation Pools 2, 3,
5, 5A and 6, which are not sampled as part of the Long Term Resource
Monitoring Program (LTRMP).  

The nuisance associated with infestations of Eurasian water milfoil has made it
the focus of both management and research.  Most correlative research about
milfoil habitat has been conducted in heavily impacted lacustrine systems. 
Patterns of Eurasian water milfoil incursions, associated changes in the native
plant community, and habitat preferences of milfoil in lotic systems have not
been well documented.  Anecdotal information and LTRMP data show that
Eurasian water milfoil is established and its occurrence fluctuates in the UMR;
however, it has not infested the river at the nuisance level found in many lakes.  In
order to understand why milfoil has not invaded this lotic environment, our
investigation attempted (1) to identify relationships between milfoil and select
abiotic factors (water depth, flow and substrate) in different river habitats, and (2)
to determine the extent of native species' association with milfoil.  Habitat types
were stratified according to geomorphological categories and select backwaters
(n=16) were sampled quantitatively in a stratified random blocks design.  Plants
were sampled along transects using a double-headed garden rake to collect wet
weights and rake densities of milfoil and native plants.  Correlations, frequencies,
taxa richness, community similarity and floral similarity were compared and
analyzed.

The qualitative component of the study focused on the distribution of native
species.  Detailed taxa lists were compiled for each pool and voucher specimens
were archived in the University of Minnesota Herbarium.  In addition, the
locations of rare species and areas with diverse vegetation were recorded and
mapped.

Keywords:  aquatic plants, submersed vegetation, Eurasian watermilfoil,
Myriophyllum spicatum, Mississippi River


Jenny Winkelman, Minnesota Department of Natural Resources, 1801 South Oak
St., Lake City, MN  55041; Tel: 612-345-3331; Fax: 612-345-3975; E-mail:
jenny_winkelman@nbs.gov
Poster (no)
Non-student