HR: 09:00h
AN: NB31E-03    [Abstracts]
TI: The Influence of Water Level Management on Hydrology, Benthic Organic Matter, and Invertebrates in Backwaters of a Mississippi River Navigation Pool.
AU: * Flinn, M B
EM: h20bugz@siu.edu
AF: Department of Zoology, Southern Illinois University-Carbondale Mailcode 6501, Carbondale, IL 62901-6501 United States
AU: Whiles, M R
EM: mwhiles@zoology.siu.edu
AF: Department of Zoology, Southern Illinois University-Carbondale Mailcode 6501, Carbondale, IL 62901-6501 United States
AU: Adams, S
EM: RAdams.fs.uca@mail.uca.edu
AF: Department of Biology, University of Central Arkansas 180 Lewis Science Center , Conway, AR 72035 United States
AU: Garvey, J E
EM: jgarvey@siu.edu
AF: Fisheries and Illinois and Illinois Aquaculture Center, Southern Illinois University-Carbondale, Carbondale, IL 62901 United States
AB: The USACE manages a 1-2ft. drawdown in the lower reaches of Mississippi River Pool 25 to stimulate moist soil vegetation production. The availability of mid-pool backwaters is relatively high and the 1-2ft drawdowns result in only ~20%-25% losses of off-channel habitat. In contrast, lower-pool reaches undergo off-channel habitat reductions of ~30%-60% and experience extensive dry periods (~60d/y). We examined the influence of these hydrologic differences on invertebrates and organic matter during 2001-2003. Stovepipe cores and zooplankton samples were collected seasonally at three mid-pool and four lower-pool backwater sites. Benthic organic matter was temporally stable at mid-pool, but lower-pool values were variable because of fluctuations in CPOM (P=0.005). Lower-pool habitats had generally higher macroinvertebrate taxa richness, with significantly higher values in spring 2002 and fall 2003 (P<0.05). Multivoltine taxa (e.g., Chironomidae, P=0.02) dominated lower-pool habitats in spring, but had higher relative abundance and biomass at mid-pool in fall. Abundance and biomass of larger, univoltine taxa such as Hexagenia were higher in mid-pool habitats (P=0.01). Zooplankton abundance was not significantly different between pool reaches, but some taxa (e.g., Cyclopoida) were more abundant in the lower pool (P=0.03). Results show water level management in this navigation pool influences backwater energy resources and communities.
DE: 9902 NABS Student Award Applied Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly