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|Title:||Effects of increased commercial navigation traffic on freshwater mussels in the Upper Mississippi River : 1992 studies|
|Authors:||U.S. Fish and Wildlife Service.|
United States. Army. Corps of Engineers. St. Louis District.
Miller, Andrew C.
Payne, Barry S.
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Technical report (U.S. Army Engineer Waterways Experiment Station) ; EL-94-14.|
Abstract: In 1988, the U.S. Army Engineer District, St. Louis, initiated a monitoring 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 1992, bivalves were collected using qualitative and quantitative (0.25-sq m total substrate) methods at dense and diverse beds at the following river miles: 299.6 (Pool 24), 450.4 (Pool 17), 504.8 (Pool 14), 571.5 (Pool 12), and 635.2 (Pool 10). Although community composition varied among sites, the unionid fauna was dominated by Amblema plicata plicata which comprised nearly 40 percent of the fauna and was taken in 85 percent of the samples. At River Mile (RM) 450.4, the overall mean density (± standard error of the mean, SE) at the nearshore site (76.4 + 4.6 individuals/sq m) was significantly greater (P < 0.05) than at the farshore site (50.8 + 5.7 individuals/sq m). At RM 572.5, mean mussel densities were not significantly different among sites (P > 0.05) Species diversity (H') ranged from slightly more than 1.5 to about 2.5 at all five mussel beds. Based on qualitative sampling methods, L. higginsi comprised 0.78 percent (three individuals) at RM 504.8 and 0.27 percent (1 individual) at RM 635.2. Based on studies conducted at RM 571.5, passage of commercial vessels appeared to have little or no effects on water turbidity (ambient turbidity ranged from approximately 38 to 90 NTU). Beds in Pools 17, 14, 12, and 10 all supported populations of A. p. plicata with relatively equal abundance of most size and age classes; the Pool 24 population was heavily dominated by a single year class (1988) of recruits. Six attributes of mussel beds were examined to judge the health of these beds: (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) ev1dence of recent recruitment, and (f) a significant change in growth rates or mortality of dominant species. An examination of these six attributes, based on information collected to date, reveals that biotic conditions are stable at these beds.
|Appears in Collections:||Technical Report|