thumbnail

Declines in aquatic vegetation in navigation pool no. 8, upper Mississippi River between 1975 and 1991

River Research and Applications

Abstract has subscript/superscript to be fixed
By:
and
DOI: 10.1002/rrr.3450110205

Links

Abstract

The biomass and frequency of occurrence of aquatic macrophytes observed during 1975 and 1991 in Navigation Pool No. 8 of the upper Mississippi River were compared. Samples were collected from contiguous backwater, isolated backwater and impounded habitat types. Overall declines were observed in both frequency and biomass between the two years. Changes in depth, water clarity and bed sediment texture were also observed. About 50% of the samples collected in 1991 had no vegetation, compared with 20% in 1975. The greatest reduction in frequency occurred among submergent taxa (77% in 1975 to 31% in 1991), whereas only slight declines were observed for emergent taxa. However, the mean biomass of both lifeforms decreased substantially (48 to 1 g/m2 for submergent and 61 to 27 g/m2 for emergent lifeforms). The mean total biomass declined from 114 g/m2 in 1975 to 35 g/m2 in 1991. Declines were most evident in the impounded habitat, where the frequency of occurrence of submergent taxa decreased from 83% in 1975 to 11% in 1991, and mean biomass decreased from 90 to 1 g/m2. Similar but less extensive reductions in frequency and biomass of submergent taxa were observed in the contiguous backwater habitat. In contrast, both the frequency and biomass of floating-leaved macrophytes increased slightly in contiguous backwater habitats. Changes in frequency and biomass of macrophytes in isolated backwater habitats were negligible between 1975 and 1991. It is hypothesized that changes in the macrophyte community structure may be related to physical changes associated with 57 years of impoundment.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Declines in aquatic vegetation in navigation pool no. 8, upper Mississippi River between 1975 and 1991
Series title:
River Research and Applications
DOI:
10.1002/rrr.3450110205
Volume
11
Issue:
2
Year Published:
1995
Language:
English
Publisher:
John Wiley & Sons, Ltd.
Publisher location:
Hoboken, NJ
Contributing office(s):
Upper Midwest Environmental Sciences Center
Description:
9 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
River Research and Applications
First page:
157
Last page:
165
Number of Pages:
9
Country:
United States
Other Geospatial:
Mississippi River