Upper Midwest Environmental Sciences Center
2001 Results in Pool 4 of the Upper Mississippi River
Sampling Effort
Sampling began June 18 and ended August 1, 2001. Of the 650 sites targeted for sampling at the beginning of the season, 646 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 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 (57% and 7%, respectively). The SAV covered about 37% 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 pool main channel border and lower Lake Pepin) supported moderate species diversity (eight and seven species, respectively). All four strata located in the upper portion of Pool 4 had few or no species at all (zero to three species). A total of 16 SAV species were recorded in the entire pool; however, most species were found either in the lower pool strata or isolated backwaters. Coontail was the most abundant species found poolwide, followed closely by water stargrass. Wildcelery was most abundant in both lower pool contiguous backwaters and secondary channels.
Rooted Floating-Leaf Vegetation
Of the three rooted floating-leaf species present in Pool 4, only two were recorded in 2001: white waterlily and American lotus. Yellow pond-lily has been recorded in other years during stratified random sampling. Poolwide, the percent frequency of all rooted floating–leaf species was fairly sparse (8%), but was dominated by white waterlily (7%). 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 was the lower pool contiguous backwater. No rooted floating-leaf species was present in any main channel border strata or any upper pool strata with the exception of upper pool contiguous backwaters.
Content manager: Danelle Larson
Page Last Modified: April 17, 2018