Upper Midwest Environmental Sciences Center
2002 Results in Pool 4 of the Upper Mississippi River
Sampling Effort
Sampling in Pool 4 began on June 17 and ended on July 17, 2002, with the exception of three sites sampled on August 9, 2002. All 630 sites targeted for sampling at the beginning of the season were sampled (Figure 1).
Submersed Aquatic Vegetation
Submersed aquatic vegetation (SAV) covered about 35.0% of the shallow water areas poolwide (Table 2; Figure 2). Isolated backwaters had the highest percent frequency of SAV (83.3%). Contiguous backwaters of lower Pool 4 (67.2%), lower Lake Pepin (25.3%), lower pool secondary channels (25.0%), lower pool main channel borders (20.0%), contiguous backwaters of upper pool (16.0%), upper Lake Pepin (8.0%), upper pool secondary channels (5.0%), and upper pool main channel borders (3.3%) followed in decreasing order. Generally, the frequency of SAV found in the combined lower pool strata (50.9%) was more than five times greater than in the combined upper pool strata (9.7%). Overall, Pool 4 had a 35.0% frequency of SAV for all strata combined.
Beds of SAV were found throughout most of the shallow water areas below Lake Pepin and in isolated backwaters located throughout Pool 4. Beds were generally absent in strata above Lake Pepin.
A total of 16 species were recorded in the entire pool. Lower pool contiguous backwaters (14) had the most species recorded followed by isolated backwaters (12), lower pool secondary channels (10), lower Lake Pepin (8), lower pool main channel border (7), and upper pool contiguous backwaters (6). Upper pool main channel border, upper pool secondary channels, and upper Lake Pepin strata each had only one species recorded.
Coontail (17.1%) was the most frequently recorded species in Pool 4 followed
by wildcelery (15.4%), water stargrass (13.8%), and Canadian waterweed
(13.3%). Coontail (73.3%) and sago pondweed (63.3%) dominated isolated
backwaters, while wildcelery (37.8%) and coontail (33.9%) were the most
frequently encountered species in lower pool contiguous backwaters. Upper
pool contiguous backwaters supported mostly sago pondweed (14%). Nodding
waternymph (16%) and water stargrass (14.7%) were the most frequently
encountered species in lower Lake Pepin, while upper Lake Pepin only supported
sago pondweed (8%). Upper pool main channel border also supported a single
species, coontail (3.3%), while lower pool main channel border was more
diverse and most frequently populated by sago pondweed and wildcelery
(15% each). Upper pool secondary channels exclusively supported sago pondweed
(5%), while lower pool secondary channels were considerably more diverse
and most frequently populated by coontail (18.3%) and wildcelery (16.7%).
Rooted Floating-Leaf Vegetation
White waterlily, American lotus, and yellow pond-lily were the three rooted floating-leaf species recorded in Pool 4. Together, all rooted floating-leaf species had a cover of about 1% and a frequency of 10% in Pool 4. The percent frequency of rooted floating-leaf species was the highest in the isolated backwaters (46.7%) and lower pool contiguous backwaters (21.7%); nearly absent in upper pool contiguous backwaters (5%) and lower pool secondary channels (3.3%), and nonexistent in all other strata.
Content manager: Danelle Larson
Page Last Modified: April 17, 2018