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Invertebrate Spatial Distribution At all stations water column and benthic samples were collected to quantify invertebrate densities in each strata. Generally, water column invertebrates dominated two communities, the open water and flooded cottonwood, whereas benthic invertebrates contributed to greater percentages in the other three communities (Figure 13). Benthic invertebrates were not found in samples of the short-lived flooded cottonwood communities but were by far the dominant organisms in the backwater and river communities. Off-channel wetland communities of the bulrush and open water had a more balanced contribution of invertebrates in both strata compared to the backwater and river communities . Mean water column invertebrate densities L'1 were highest in the flooded cottonwood followed by the open water, and bulrush communities (Figure 14). The backwater and river communities were nearly devoid of water column invertebrates with densities of 0.10 and 0.05 organisms L'1 (not apparent due to graph scale), respectively. Benthic invertebrate densities were highest in the bulrush followed by the open water, backwater and river communities. Again, no benthic organisms were found in our flooded cottonwood community samples. Off-channel wetland communities produced greater densities of benthic organisms than did the backwater and river communities. Mean water column Cladocera and Copepoda densities were nearly equal in the bulrush community but copepods dominated the open water with nearly double the density of the cladocerans over the season (Figure 15). Flooded cottonwood stations were dominated by Cladocera with mean densities that far exceeded any other taxa in any other community with 53 L-1. Both the backwater and river communities had greater densities of chironomid larvae than any other water column invertebrate group. The bulrush and open water communities both had ali five invertebrate groups implying greater species richness. The backwater and river communities both had low mean densities of the Cladocera group with 0.07 and 0.01 L'1, respectively. cladocerans were the most abundant of the taxonomic groups in the backwater community. Copepoda densities were also low in the backwater and river communities 0.01 and 0.02 L'1, respectively. Copepods were the most abundant taxonomic group in the river community. No members of the other invertebrate taxonomic groups were found in the river community. The flooded cottonwood community was comprised only of cladocerans and copepods, with cladocerans dominating. Densities of all taxonomic groups were always higher in off-channel wetlands (bulrush and open water) than in the backwater and river communities. 23