HR: 15:30h
AN: NB44A-01    [Abstracts]
TI: Macroinvertebrates Associated With Dikes in the Mississippi River: Spatial and Temporal Patterns
AU: * Battle, J
EM: jbattle@stroudcenter.org
AF: Stroud Water Research Center, 970 Spencer Road, Avondale, PA 19311
AU: Jackson, J K
EM: jkjackson@stroudcenter.org
AF: Stroud Water Research Center, 970 Spencer Road, Avondale, PA 19311
AU: Sweeney, B W
EM: sweeney@stroudcenter.org
AF: Stroud Water Research Center, 970 Spencer Road, Avondale, PA 19311
AB: Fine sediments and rocky substrates are dominant benthic macroinvertebrate habitats in the Mississippi River. We sampled macroinvertebrates in fine sediments downstream of wing dikes on four occasions and on rocks upstream of wing dikes on two occasions. We identified 65 taxa in the fine sediments and 50 taxa on the rocks, with only 26 taxa found in both habitats. Presumably, assemblage differences reflect flow and substrate differences. Assemblages in both habitats exhibited considerable temporal variability. Macroinvertebrate densities in the fine sediments ranged from 3737 to 8706 individuals m^-2 y^-1, with oligochaetes representing 77-92% of total density. Macroinvertebrate density on the rocks ranged from 57,770 to 162,966 individuals m^-2 y^-1, with hydropsychid caddisflies (Hydropsyche bidens/orris and Potamyia flava) representing 82-97% of total density. A literature survey found that macroinvertebrate assemblages in large rivers of the Mississippi River Basin (e.g., Upper and Lower Mississippi, Illinois, Ohio, and Missouri Rivers) tend to be dominated by a few taxa. Because of this, we believe that traditional approaches to describing community structure (e.g., species richness, relative abundance) in biological assessments may be insensitive to subtle differences among large river faunas.
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly