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|Title:||Benthic macroinvertebrates of selected aquatic habitats of the Lower Mississippi River|
|Authors:||Environmental and Water Quality Operational Studies (U.S.)|
Beckett, David C.
Bingham, C. Rex.
Sanders, Larry G.
Mathis, David B.
Lower Mississippi River
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: This report describes benthic macroinvertebrate composition and distribution in four aquatic habitat types within a 60-mile reach of the Lower Mississippi River. The macroinvertebrate biotas of the four habitat types, dike fields (three), a natural bank, a secondary channel, and an abandoned channel, were studied over one high flow (flood stage), two moderate, and two low flow periods between April 1979 and September 1980. The biotas present in the natural bank, secondary channel, and abandoned channel showed only minor changes in composition over the various flow regimes. The natural bank was consistently dominated (numerically) by the burrowing mayflies Tortopus incertus and Pentagenia vittigera and hydropsychid caddisflies. The consistently most common taxa in the secondary channel were the sand-dwelling chironomids Robackia claviger and Chernovskiia orbicus. Phantom midges, tubificid oligochaetes, and fingernail clams were always the most abundant macroinvertebrates in the abandoned channel. Macroinvertebrate densities were always high in the mud-bottomed abandoned channel and were always low in the strong current, sandy substrate habitat of the secondary channel. Unlike the other habitats, the dike fields showed large changes in biotic composition, which correlated with changes in river stage and resultant alterations in current and substrate. With decreased river stages current velocity was greatly reduced in each of the dike fields and substrate dominance changed from erosional (sand and gravel) to depositional (silt). Consequently, the dike field macroinvertebrate communities, which were intermediate in biotic similarities between the communities in the secondary channel and the abandoned channel at high and moderate flows, showed marked similarities at low flows to the macroinvertebrate community present in the slack-water, mud-bottomed abandoned channel. This study indicates that the distribution of macroinvertebrates in the Lower Mississippi River habitats is a function of the physical characteristics of the system, notably current velocity and substrate composition.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Technical Report|
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|Technical Report E-83-10.pdf||3.96 MB||Adobe PDF|