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Presented at the NABS Annual meeting, Anchorage, Alaska, 2006
in Large River Ecology 2
Spatial patterns of macroinvertebrate communities and the importance of off-channel habitats in Mississippi River Pool 25.
M.B. Flinn1, M.R. Whiles1,2, S.R. Adams3, and J.E. Garvey2.1Department of Zoology, Southern Illinois University, Carbondale, IL 62901, 2Fisheries and Illinois Aquaculture Center, Southern Illinois University, Carbondale, IL 62901 , 3Department of Biology, University of Central Arkansas, Conway, AR 72035
Macroinvertebrate communities were examined in off-channel habitats of Mississippi River Navigation Pool 25 located 0.1–1.9 km from the main channel. Thirteen sites were sampled immediately before and after the spring flood pulse during 2002. Sites were grouped into four types: island sloughs, island fringes, backwaters, and artificial substrates. Three 30–m transects parallel to the shore were sampled at each site with a dipnet and habitat measurements were made at 1–m increments on five transects perpendicular to the shore. NMDS identified significant spatial structuring in physical and biological variables. ANOSIM analysis reaffirmed differences in sites based on physical and biological data. During the rising limb, island sloughs were different from island fringes (P<0.01). Between sampling dates, island sloughs were significantly different from island fringes and backwaters (all P<0.01). Post–flooding, no significant differences were evident among sites. Vector analysis indicated dissolved oxygen, temperature, % sand, and % wood were linked to differences among sites. Repeated measures ANOVA also showed higher overall macroinvertebrate abundance and diversity after the flood pulse (P<0.05). Results underscore the importance of habitat diversity on fine spatial and temporal scales in this highly managed system, and suggest that management and restoration efforts should target island sloughs.
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