A PROFILE OF SUBMERSED AQUATIC VEGETATION ON POOL 8  OF  THE  UPPER
MISSISSIPPI RIVER SYSTEM

Heidi Langrehr.
Wisconsin Department of Natural Resources, 575 Lester Avenue, Onalaska, WI 
54650. 

In 1998, the Long Term Resource Monitoring Program initiated a stratified random 
sampling protocol to monitor submersed aquatic vegetation (SAV) in the Upper 
Mississippi River System.  The primary objective of the monitoring is to determine the 
status and trends of SAV within target pools.  During the summers of 1998 and 
1999, SAV data was collected in Pool 8 at randomly chosen sites (550 in 1998, 600 
in 1999) distributed within shallow aquatic areas (<= 3 m in 1998 and <= 2.5 m in 
1999).  The shallow aquatic areas were classified into 5 habitat strata including 
contiguous and isolated backwaters, main and side channel borders, and impounded. 
Data collected included both visual and rake samples.  Percent frequency was 
calculated by dividing the number of sites containing SAV by the total number of 
sites.  The data enable us to construct a profile of SAV in Pool 8 as well as in each 
habitat stratum.

Overall, Pool 8 showed an increase in SAV from 1998 (50%) to 1999 (57%).  Fifteen 
species were recorded in 1998 and 1999 with the highest number recorded in 
contiguous backwaters (13 and 14 respectively).  Isolated backwaters contained the 
most SAV in both years followed closely by contiguous backwaters.  Isolated 
backwaters showed a decrease in SAV from 1998 to 1999 while all other strata 
increased.  Canadian waterweed (Elodea canadenis Michx.) and coontail 
(Ceratophyllum demersum L.) were the most frequently encountered species in both 
years.  Coontail was the most abundant species in isolated and contiguous 
backwaters in 1998 and 1999.  Canadian waterweed was most abundant in 1998 in 
impounded and side channel border sites while water stargrass (Heteranthera dubia 
[Jacq.] MacM.) was most abundant in 1999.  Wild celery (Vallisneria americana 
Michx.) dominated the main channel border stratum in 1998 and sago pondweed 
(Potamogeton pectinatus L.) dominated in 1999.  Coontail, Eurasian watermilfoil 
(Myriophyllum spicatum L.), and sago pondweed were distributed throughout the 
pool.  Wild celery, however, was limited to the lower half of the pool.  

Keywords:  submersed aquatic vegetation, Mississippi River, trend analysis, 
distribution
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