AQUATIC VEGETATION IN NAVIGATION POOL 11 OF THE UPPER MISSISSIPPI RIVER SYSTEM

Jeffrey A. Yanke1,2 and Yao Yin1
1U.S. Geological Survey, Upper Midwest Environmental Sciences Center, 2630 Fanta 
Reed Road, La Crosse, WI 54602; 2River Studies Center, University of Wisconsin-
La Crosse, La Crosse, WI 54601.

Our primary objective was to collect baseline data on the aquatic vegetation in 
Pool 11 of the Upper Mississippi River System (UMRS) using current Long Term 
Resource Monitoring Program (LTRMP) protocol.  During the summer of 2001, 
aquatic vegetation data was collected at 568 randomly selected sites distributed 
in five separate aquatic habitat types, including main channel border, side 
channel, contiguous backwaters, isolated backwaters, and impounded.  Data 
collection was based upon both visual observation and rake sampling.  Stratified 
random sampling facilitated a stratum-wide as well as pool-wide assessment of 
aquatic vegetation composition and distribution. 

A total of thirteen species of submersed aquatic vegetation (SAV) were recorded 
during our sampling efforts.  Sago pondweed (Potamogeton pectinatus L.) was the 
most abundant submersed aquatic plant overall based on frequency (recorded in 9% 
of total sites), followed by coontail (Ceratophyllum demersum L.) and wild 
celery (Vallisneria americana Michx.).  Coontail dominated the side channel, 
backwater contiguous, and backwater isolated habitats while sago pondweed was 
most abundant in main channel border and impounded areas.  Isolated backwaters 
contained the highest frequency of submersed and rooted floating leaf aquatic 
vegetation (73% and 47%, respectively).  Impounded areas accounted for the 
highest species richness of submersed aquatic vegetation (8), despite moderate 
frequencies (12%).  These results differed from the two nearest target pools (8 
& 13), where backwater contiguous areas contained the highest number of species 
(12 and 11, respectively).  Contiguous and isolated backwaters accounted for the 
highest frequencies of rooted floating leaf species (23% and 46%, respectively).  
The American lotus (Nelumbo lutea) was the most common rooted floating leaf 
species recorded (6%).  In pool 13, the American lotus was also the dominant 
rooted floating aquatic (9%), whereas the white waterlily (Nymphaea odorata) was 
most frequent in pool 8.    

Keywords:  submersed vegetation, aquatic plants, Mississippi River, trend 
analysis, stratified random sample