Macroinvertebrate communities in littoral regions of a large
  river-floodplain:  relationships with water quality and
  vegetation.  
  
  Timothy B. Mihuc1,2. 1Great Rivers Field Station, Long Term Resource
  Monitoring Program- reach 26,  Illinois Natural History Survey, Alton, Il
  62002.  2LA Cooperative Fish and Wildlife Research Unit, School of
  Forestry, Wildlife and Fisheries, Louisiana State University, Baton Rouge,
  LA 70803. 
  
  
     Distribution and habitat requirements of aquatic macroinvertebrates
  among native and exotic macrophytes in the Atchafalaya River Basin,
  Louisiana were examined in 1994-1995.  The Atchafalaya is the major
  distributary in the lower Mississippi River delta, representing the largest
  contiguous hardwood swamp and the sixth largest river in the U.S.  The
  Atchafalaya Basin contains one of the few intact large river-floodplain
  systems remaining in the U.S., retaining at least half of its original
  floodplain.  Sampling involved vertical littoral net hauls taken at 49 sites
  encompassing 9 vegetation types and 2 water quality types (blackwater,
  brownwater).  Differences in habitat use among taxa were compared using
  multivariate analyses.   Differences in community structure were apparent
  between vegetation types but less evident between water quality types. 
  Exotic water hyacinth (Eichhornia crassipes) and Hydrilla verticillata
  showed an altered macroinvertebrate community structure versus most
  native macrophyte habitat (Ceratophyllum demersum, Nelumbo lutea,
  Cabomba, Vallisneria americana,and Najas).  Native Saggittaria, however,
  harbored a similar animal community as water hyacinth.  Differences were
  also found between the two exotic types.  In summary, native macrophytes
  contained similar invertebrate communities that were disimilar from both
  exotic macrophytes.  Furthermore, the two exotic macrophytes differed
  from one another in community structure.   The impact of exotic
  macrophyte introductions and the ongoing Dreissena invasion on aquatic
  animal communities in the Atchafalaya River Basin appears to be severe,
  resulting in re-structuring of macroinvertebrate communities from the
  indigenous state.   
  
  Keywords: large river-floodplain, macrophytes, macroinvertebrate
  community, Atchafalaya-Mississippi River.
  
  
  
  Dr. Tim Mihuc, Director
  Great Rivers Field Station, LTRM pool 26
  Illinois Natural History Survey
  Alton, IL 62002
  ph. 618-466-9690       fax 618-466-9688         
  email- Tim_Mihuc@nbs.gov