HR: 10:45h
AN: NB32A-02    [Abstracts]
TI: Assessment of Instream Restoration in the Cache River, Illinois: Macroinvertebrate Community Structure on Rock Weirs Compared to Snag and Streambed Habitats
AU: * Walther, D A
EM: denise@siu.edu
AF: Southern Illinois University Carbondale, Department of Zoology, Carbondale, IL 62901-6501 United States
AU: Whiles, M R
EM: mwhiles@zoology.siu.edu
AF: Southern Illinois University Carbondale, Department of Zoology, Carbondale, IL 62901-6501 United States
AB: Rock weirs were constructed in a degraded section of the Cache River in southern Illinois in 2001 and 2003 to prevent channel incision and protect riparian wetlands. We sampled macroinvertebrates in two older weirs and in two sites downstream of the restored section in April 2003, October 2003, and April 2004 to evaluate differences in community structure between weir, snag, and streambed (scoured clay) habitats. Three recently constructed weirs were also sampled in April 2004. Functional composition differed among sample dates and habitats. Although collector-gatherers consistently dominated streambed habitats, functional composition on weirs and snags was more variable. Filterer and predator biomass was generally higher on weirs, and snags harbored the only shredders collected in the system (Pycnopsyche spp.). Weirs generally supported higher biomass of Ephemeroptera, Plecoptera, and Trichoptera than other habitats. For example, mean EPT biomass on weirs in 2003 (April=187 mgAFDM/m²; October=899 mgAFDM/m²) was 4 to 10-fold higher than EPT biomass in snag or streambed habitats. Late instar Pycnopsyche contributed 41% of snag biomass in April 2004, resulting in EPT biomass similar to rock weirs. Results indicate rock weirs provide suitable stable substrate for macroinvertebrates and may enhance populations of sensitive EPT taxa in degraded systems.
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly