Upper Midwest Environmental Sciences Center
2002 Results in Pool 8 of the Upper Mississippi River
Sampling Efforts
Sampling in Pool 8 began on June 17 and ended on August 1, 2002. Of the 650 sites targeted for sampling at the beginning of the season, 644 were sampled (Figure 7). A drawdown was conducted in Pool 8 in 2002. It began on June 17 and was terminated on September 15, 2002. This was the second year a drawdown was conducted in Pool 8.
Submersed Aquatic Vegetation
Submersed aquatic vegetation (SAV) covered about 53.4% of the shallow water areas poolwide and was found throughout most of the pool (Table 5; Figure 8). Isolated backwaters had the highest percent frequency of SAV (89%). Contiguous backwaters (76%), impounded areas (47%), secondary channels (29%), and main channel border (17%) followed in decreasing order.
Sizable beds were found throughout most of the shallow water areas, except in the lower portion of the pool where sizable beds were generally absent.
A total of 15 species were recorded in the entire pool. Contiguous backwaters (13) had the most species recorded followed by impounded areas (12), and secondary channels (11). Isolated backwaters and main channel border areas both had 8 species recorded.
Canadian waterweed (31%) was the most frequently recorded species in
Pool 8 followed by water stargrass (28%) and coontail (28%). Canadian
waterweed (55%) and coontail (54%) dominated contiguous backwaters, while
coontail (89%) was the most frequently encountered species in isolated
backwaters. In impounded areas, water stargrass (38%) and wildcelery (31%)
were the most frequent species. Sago pondweed (11%) was dominant in main
channel border areas, while Canadian waterweed (17%) was most frequently
encountered in secondary channels.
Rooted Floating-Leaf Vegetation
White waterlily, American lotus, and yellow pond-lily were the three rooted floating-leaf species recorded. The three species together covered about 6% of the shallow water areas.
The percent cover of rooted floating-leaf species was the highest in isolated backwaters (40%) followed by contiguous backwaters (12%). Main channel border areas, impounded areas, and secondary channels all had about 2% of the area covered by rooted floating-leaf species.
White waterlily and American lotus were scattered throughout much of
the upper two-thirds of Pool 8, while yellow pond-lily had a much more
limited distribution.
Comparison of 2001 and 2002 Results
Overall, submersed vegetation percent frequency increased slightly from 2001 to 2002, but species composition remained the same. Three species increased by about 10% including water stargrass, Eurasian watermilfoil and Canadian waterweed. The impounded strata showed the largest change in percent frequency from 2001 to 2002 increasing by 10%. Within the impounded strata, wildcelery, Eurasian watermilfoil, Canadian waterweed, and water stargrass increased by 10% or more. Rooted floating-leaf vegetation frequency and species composition remained about the same from 2001 to 2002.
Content manager: Danelle Larson
Page Last Modified: April 17, 2018