Effects of Increased Commercial Navigation Traffic on Freshwater Mussels in the Upper Mississippi River: 1989 Studies
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS ENVIRONMENTAL LAB
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In 1988, the US Army Engineer District, St. Louis CELMS 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 UMR. In 1989 mussels were collected using qualitative and quantitative methods 0.25 - sq - m total substrate samples at dense and diverse beds in pool 24 river mile RM 299, pool 14 RM 505, and pool 10 RM 635 of the UMR. Water velocity and suspended solids concentrations were measured immediately following vessel passage at beds in pools 10 and 14. An assessment of commercial navigation traffic effects will be based on a comparison of baseline data 1988 - 94 with information collected with less intensive sampling from 1994 to 2040. The UMR mussel fauna was dominated by Amblema plicata, which comprised 27.7 percent of the qualitative collection, and was found in 87.1 percent of the samples. Total numbers of the endangered L. higginsi were variable this species comprised slightly less than 0.5 percent of the bivalve assemblage and ranked 22nd out of 26 species collected using qualitative methods. Total bivalve density ranged from 31.2 or - 25.7 or - SD individuals sq m to 184.8 or- 33.3 individualssq m at 24 sites on three mussel beds.