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|Title:||Effects of increased commercial navigation traffic on freshwater mussels in the Upper Missisippi River : 1994 studies|
|Authors:||Miller, Andrew C.|
Payne, Barry S.
|Keywords:||Freshwater mussels--Mississippi River|
|Publisher:||Environmental Laboratory (U.S.)|
U.S. Army Engineer Waterways Experiment Station.
|Series/Report no.:||Technical Report ; EL-95-33|
|Abstract:||In 1988, the U.S. Army Engineer District, St. Louis, initiated a monitoring program to analyze the effect of commercial navigation traffic on freshwater mussels (Mollusca: Unionidae), especially the endangered Lampsilis higginsi, in the upper Mississippi River (UMR). Preliminary studies were conducted in 1988, and detailed studies were initiated in 1989 and continued until 1994. In July 1994, the last year of this study, qualitative and quantitative data (0.25 m² total substratum samples) were collected at the following locations: Pool 24 (River Mile (RM) 299.6), Pool 17 (RM 450.4), Pool 14 (RM 504.5), Pool 12 (RM 571.4), and Pool 10 (RM 635.2, main channel). This research was funded by the U.S. Army Engineer District, St. Louis, to assess the effects of existing and projected future increased navigation traffic levels on freshwater mussels, including the endangered Higgins eye mussel, Lampsilis higginsi. A total of 26 species of bivalves were collected, including two exotic species, the Asiatic Clam, Corbicula fluminea, and the zebra mussel, Dreissena polymorpha. During this study year, zebra mussels were still a minor component of the bivalve assemblage; density ranged from 0.27 ± 0.13 at RM 299.6 to 8.2 ± 1.29 individuals/m² at RM 504.8. Based on quantitative samples at five beds, species diversity ranged from 1.78 to 2.28, and total species richness ranged from 16 to 20. The percentage of native bivalves less than 30-mm total shell length, evidence of recent recruitment, was approximately 30 at all sites except in Pool 10 at RM 635.2 where it was only 12.8. The percentage of species that were evidence of recent recruitment ranged from a low of 43.7 at RM 299.6 to 60.0 at RM 571.5. Density of native mussels ranged from a low of 16.2 ± 1.90 (Standard Error, SE) at RM 299.6 to a high of 51.5 ± 4.98 at RM 504.8. One L. higginsi was collected using qualitative methods at the bed in Pool 17. At RM 504.8, L. higginsi represented 0.76 and 0.44 percent of the qualitative and quantitative collection, respectively. Lampsilis higginsi was not found at RM 571.5, but it was collected using quantitative methods in Pool 10. Analysis of Amblema plicata plicata from all pools clearly indicates that mortality takes a heavy toll on individuals approximately 90 mm long or greater. Mortality of Leptodea fragilis takes many individuals before they reach average adult size. The commercially valuable Megalonaias nervosa ranges from 30 to 90 mm long, which indicates steady, moderately strong recruitment to the population. As with previous study years, biotic conditions appeared stable at these beds. No adverse effects caused by movement of commercial vessels were found. Density, evidence of recent recruitment, and population demography of dominant populations appeared to be unaffected by the high water of 1993.|
|Gov't Doc #:||Technical Report EL-95-33|
|Rights:||Approved for Public Release; Distribution is Unlimited|
|Size:||112 pages/10.48 Mb|
|Appears in Collections:||Technical Report|
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