Seasonal and Spatial Distribution of Zooplankton in a Food Control Reservoir and Tailwater.
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS ENVIRONMENTAL LAB
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Zooplankton, when available, may be an important food source for fish fry in lotic habitats. The effects of flood control reservior operation on the downstream transport of reservior zooplankton both microcrustaceans and rotifers were quantified by examining zooplankton abundances in Barren River Lake, Kentucky, and three downstream stations from August 1980-August 1981. The decrease noted in microcrustacean and rotifer abundance downstream from the dam was attributed to predation, physical destruction, and lack of suitable habitat. During stratification May-September, the abundance of zooplankton was greater in the tailwater than in the reservior hypolimnion this difference in abundance suggests that water and associated organisms were being withdrawn from upper levels in the reservior--as well as from the hypolimnion, where most of Barren River Lakes releases come from and which normally harbors few viable zooplankters. The unstratified reservior usually contained higher densities of zooplankton than the tailwater. The results of the study led to the conclusion that implementation of operational procedures to increase discharge of reservior zooplankton to the tailwater may not be warranted since the complexity of factors determining reservior zooplankton dynamics precludes their use as a reliable food source for tailwater biota.