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|Title:||Aquatic habitat studies on the lower Mississippi River, river mile 480 to 530. Report 4, Diel periodicity of benthic macroinvertebrate drift|
|Authors:||Environmental and Water Quality Operational Studies (U.S.)|
Bingham, C. Rex.
Cobb, Stephen P.
Magoun, A. Dale.
Lower Mississippi River
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: 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-μm 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 organisms/100 m³ 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. Hydropsyche spp., the most abundant taxon, was nocturnally active. Hydra sp., a diurnal drift component, was the second most dominant taxon. Species diversity in the drift exhibited diel periodicity and was significantly lower (P < 0.05) during daylight hours and highest at dusk, midnight, and dawn. Of the nine most dominant taxa, five were most abundant at midnight, two most abundant at dusk, one most abundant at afternoon, and one most abundant at noon. Various taxa exhibited behavioral drift characteristics. The total transport of benthic drift downstream in a 24-hr period was calculated as 2.9 x 10^10 organisms/day based on a river discharge of 12,063 m³/sec. Total diel drift standardized by river discharge was 2.44 x 10^6 organisms/day/m³/sec, slightly higher than reported for other rivers but of the same order of magnitude.
|Appears in Collections:||Miscellaneous Paper|