Successional changes in habitat caused by sedimentation


Bhowmik, N. G., and J. R. Adams.  1989.  Successional changes in
habitat caused by sedimentation in navigation pools. 
Hydrobiologia 176/177:17-27.  Reprinted by U.S. Fish and Wildlife
Service, Environmental Management Technical Center, Onalaska,
Wisconsin, April 1993.  EMTC 93-R025.  11 pp.  (NTIS #PB94-1102372


ABSTRACT

Upstream of St. Louis, Missouri, navigation on the Upper
Mississippi River is made possible by a series of lock and dam
structures.  Many of the pools formed by these navigation dams
have nearly reached a new equilibrium condition for scour and
deposition of sediment.  Several pools with extensive backwater or
channel border areas are still accumulating sediment at rates
similar to those for man-made lakes.  The original open-water
habitats in these pools are changing to aquatic macrophyte beds
and then to marsh or terrestrial floodplain conditions because of
sediment deposition.  Two pools are used as examples of this
phenomenon:  (1) Pool 19 on the Mississippi River was formed when
the lock, dam, and power house at Keokuk, Iowa, were completed in
1913; and (2) Peoria Lake, which has been affected by the
diversion of Lake Michigan water into the Illinois River in 1900
and the construction of a lock and dam in 1939.  Both pools have
had well over 50% of their original volume filled with sediment. 
Three areas in Pool 19 illustrate the successional changes that
occur as sedimentation raises the river bottom into the photic
zone.  Sedimentation has made boating impossible on large areas of
both pools. The continuing process is likely to change open waters
to floodplains.  Peoria Lake lacks aquatic plant beds because of
excessive turbidity and frequent resuspension of bed material by
wind- or boat-generated waves.  It seems likely that these river
reaches will become a narrow channel without any broad and highly
productive channel borders.


KEYWORDS

Mississippi River, wetlands, sedimentation