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|Title:||Effects of increased commercial navigation traffic on freshwater mussels in the Upper Mississippi River : 1991 studies|
|Authors:||Miller, Andrew C.|
Payne, Barry S.
|Keywords:||Freshwater mussels--Mississippi River--Effect of habitat on|
Mussels--Mississippi River--Effect of sediment on
Unionidae--Effect of habitat on
Inland navigation--Environmental aspects
|Publisher:||Environmental Laboratory (U.S.)|
U.S. Army Engineer Waterways Experiment Station.
|Series/Report no.:||Technical Report;EL-93-1|
|Abstract:||In 1988, the US Army Engineer District, St. Louis, initiated a program to analyze the effects of commercial navigation traffic on freshwater mussels (Mollusca: Unionidae), especially the endangered Lampsilis higginsi, in the upper Mississippi River. Preliminary studies were conducted in 1988; detailed studies were initiated in 1989 and will continue for at least 6 years. In July 1991, mussels were collected using qualitative and quantitative (0.25 sq m total substratum) methods at dense and diverse beds in Pool 24 (river mile (RM) 299.6), Pool 14 (RM 504.8), and Pool 10 (RM 635.2). Water velocity and suspended solids concentrations were measured immediately following vessel passage near sites where mussels were collected in Pools 24 and 10. An assessment of commercial navigation traffic effects will be based on a comparison of baseline data (1988-94) with data collected during periods of increased traffic intensity following 1994. In qualitative samples collected in 1991, Amblema plicata plicata dominated and comprised 41.02 percent of the fauna. Fifteen species were common and comprised from 8.73 to 1.57 percent of the collection, and 12 species made up less than 1 percent of the assemblage. Mean bivalve density (N - 30) was least in Pool 24 (5.1 to 35.l individuals/sq m), moderate in Pool 10 (62.7 to 52.1 individuals/sq m), and highest in Pool 14 (81.4 to 84.8 individuals/sq m). Lampsilis higginsi, an endangered species, comprised 0.71 percent (14 individuals) and was found in nearly 10 percent of all qualitative samples. Velocity changes caused by vessel passages at sites where mussels were present in Pools 24 and 14 were either not measurable or minor. When measurable, vessels caused a surge or reduction in velocity of usually no more than double ambient velocity. Six attributes of mussel beds were examined based on 4 years of sampling: (a.) decrease in density of five common-to-abundant species, (b.) presence of L. higginsi (if within its range), (c.) live-to-recently-dead ratios for dominant species, (d.) loss of more than 25 percent of the mussel species, (e.) evidence of recent recruitment, and (f.) a significant change in growth rates or mortality of dominant species. Based on sampling methods, these parameters are stable at beds in Pools 24, 14, and 10.|
|Appears in Collections:||Technical Report|
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