Aquatic Habitat Studies on the Lower Mississippi River, River Mile 480 to 530. report 4. Diel Periodicity of Benthic Macroinvertebrate Drift.
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS ENVIRONMENTAL LAB
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A diel periodicity study of drifting benthos in the lower Mississippi River at mile 529 resulted in the collection of 5090 macroinvertebrates consisting of 80 taxa. Samples collected with 505 micrometer mesh, 0.5-m mouth diameter plankton nets at midnight 0100 hr, dawn 0600 hr, noon 1200 hr, afternoon 1600 hr, and dusk 2100 hr on 27-28 June 1978, had an average total drift density over all sampling times of 140 organisms100 cubic meters of water filtered. Total drift density did not fluctuate markedly over the five sampling times, except that concentrations were significantly lower P 0.05 at dawn than at other times. The lack of pronounced diel periodicity in total drift resulted from the offsetting of dominant day active versus night active species.
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