Upper Midwest Environmental Sciences Center
2000 Results in Pool 4 of the Upper Mississippi River
Sampling Effort
Sampling began June 15 and ended July 28, 2000. Of the 635 sites targeted for sampling at the beginning of the season, 631 were sampled while four were not sampled because of inaccessibility (Figure 1).
Submersed Aquatic Vegetation
The status of submersed aquatic vegetation (SAV) in Pool 4 varied among the strata sampled. Isolated backwaters had the highest abundance of SAV (Table 2; Figure 2), followed by the contiguous backwaters of the lower pool, lower Lake Pepin, secondary channels of the lower pool, lower pool main channel borders, upper pool contiguous backwaters, upper Lake Pepin, upper pool main channel borders and secondary channels of the upper pool. In general, the lower pool contained significantly more SAV than the upper pool (55.3% and 13.8%, respectively). The SAV covered about 39% of the shallow water areas poolwide.
Of the nine strata sampled in Pool 4, only three (isolated backwaters and both lower pool contiguous backwaters and secondary channels) supported a rich diversity of species (10 or more species per strata). Two strata (lower Lake Pepin and lower pool main channel border) supported moderate species diversity (nine and seven species, respectively). In the upper portion of the pool, all of the strata had few or no species (zero-one species) with the exception of upper pool contiguous backwaters that had four species. A total of 15 SAV species were recorded in the entire pool; however, most species were found in the lower pool, specifically the contiguous backwaters. Coontail and water stargrass were the most abundant species found poolwide, followed closely by wildcelery, sago pondweed, and Canadian waterweed. Wildcelery was most abundant in both lower pool contiguous backwaters and secondary channels.
Rooted Floating-Leaf Vegetation
All three rooted floating-leaf species present in Pool 4 (white waterlily, yellow pond-lily, and American lotus) were recorded in 2000. Poolwide, the percent frequency of all rooted floating-leaf species was fairly sparse (9.4%), but dominated by white waterlily (8.3%). Isolated backwaters had the highest percent cover of rooted floating-leaf vegetation that consisted entirely of white waterlily. The only stratum that harbored American lotus and yellow pond-lily was the lower pool contiguous backwater. Aside from isolated backwater sites, rooted floating-leaf species were only recorded in contiguous backwaters of both lower and upper pool, and secondary channels of the lower pool. All other strata were void of rooted floating-leaf species.
Content manager: Danelle Larson
Page Last Modified: April 17, 2018