Upper Midwest Environmental Sciences Center
2001 Results in Pool 8 of the Upper Mississippi River
Sampling Efforts
Sampling began on June 15 and ended on July 24, 2000, in Pool 8, Upper Mississippi River System. Of the 650 sites targeted for sampling at the beginning of the season, 649 were actually sampled (Figure 3). One site was not sampled because of inaccessibility.
Submersed Aquatic Vegetation
The status of submersed aquatic vegetation (SAV) in Pool 8 varied among the strata sampled. Isolated backwaters had the highest abundance of SAV (Table 3; Figure 4). Contiguous backwaters, impounded areas, secondary channels, and main channel border areas followed in decreasing order. Sizable beds were found throughout most of the shallow water areas, except in the main channel border areas and the lower terminate of the pool where sizable beds were generally absent. The SAV covered about 47.7% of the shallow water areas poolwide.
Contiguous backwaters harbored the richest assemblage of submersed plant species (15). Impounded and secondary channel areas had 11 species recorded while main channel border areas and isolated backwaters both had 9 species. A total of 16 species were recorded in the entire pool. Coontail was the most abundant species in isolated and contiguous backwaters, while water stargrass and wildcelery were most abundant in the impounded areas. No species was more abundant in secondary channels and main channel border areas.
Rooted Floating-Leaf Vegetation
White waterlily, American lotus, and yellow pond-lily were the three rooted floating-leaf species recorded. The percent cover of rooted floating-leaf species was the highest in the isolated backwaters. White waterlily was scattered in much of the isolated and contiguous backwaters, while American lotus had a much more limited distribution. Yellow pond-lily was found only in contiguous backwaters. The three species together covered about 4.9% of the shallow water areas.
Comparison of 1999 and 2000 Results
Overall, submersed vegetation decreased in frequency and abundance index from 1999 to 2000, while species composition remained about the same. Most of the decrease occurred in contiguous backwaters and impounded areas and was mostly because of decreases in water stargrass and Canadian waterweed. Rooted floating-leaf species composition and frequency remained about the same from 1999 to 2000, but cover decreased indicating the average amount of vegetation at each site was less.
Content manager: Danelle Larson
Page Last Modified: April 17, 2018