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e <br />The plankton density in the floodplain is 29x greater than the backwater and 157x <br />greater than the river. Welcomme (1979) found up to 30x the biomass in side arms as <br />compazed to the river and Hamilton et al. (1990) reported densities in a floodplain <br />lake 100x greater than the river densities. <br />of <br />Six species of calanoids, all members of the Genus Diaptomus, were reported in <br />this study. Four of these were only collected during a single sampling period at a <br />single site (Table 3.). Mahoney et al. (1990) summarized the number of calanoid <br />species from 16 studies of temporary ponds. The maximum number reported by <br />Mahoney is five per pond or seven per study area. Repsys and Rogers (1982) report <br />collecting seven diaptomids along the Missouri River. They state that "this represents <br />the largest congeneric association of diaptomids reported outside the Great Lakes" . <br />While they state that D. ashl di and D. si ilis aze restricted primarily to the northern <br />most states and Great Lakes, these two species were also collected during this study <br />in very low numbers. <br />The diaptomids, D. iciloi a ,and D. albuauerau~ sis, were collected in the <br />benthos of both the floodplain and river sites. Evans and Stewart (1977) list the genus <br />Eurytemora as being epibenthic but no calanoids were benthic. Their study, however, <br />did not include the benthic species that were collected in the present study. It is <br />possible that these species, while not preferring the benthos, can adapt to a benthic <br />existence. <br />18 <br />