Accession Number : ADA181439

Title :   Vertical, Horizontal, and Diel Distribution of Invertebrate Drift in the Lower Mississippi River.

Descriptive Note : Final rept.,

Corporate Author : ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS ENVIRONMENTAL LAB

Personal Author(s) : Beckett,David C ; Kasul,Richard L

PDF Url : ADA181439

Report Date : Mar 1987

Pagination or Media Count : 39

Abstract : Lower Mississippi River macroinvertebrate drift densities and composition were determined at 3-hr intervals over 24-hr periods in mid-May and early June 1982. Samples were taken at the surface, middepth, and near the bottom at a nearshore sampling station and the surface and middepth at a sampling near the navigation channel. The overall mean drift density equaled 35.0 invertebrates/100 m3 of water. Overall, Chaoborus larvae were the most common invertebrates collected, followed, respectively, by chironomid pupae, Hydra sp., Hydropsyche orris, and Hexagenia sp. The abundance of various taxa in the Lower Mississippi River's drift seem to change markedly on a site-to-site basis, as a function of the physical characteristics of the river and its substrates in a certain area. This site-to-site heterogeneity, coupled with the lack of lateral homogeneity and the definite diel periodicity exhibited by some taxa, provides evidence that, even in an immense river such as the Mississippi, many of the organisms drift as they do in small streams, traveling relatively short distances with total movement rather saltatory. Keywords: Marine biology

Descriptors :   *INVERTEBRATES, *AQUATIC INSECTS, CHANNELS(WATERWAYS), DENSITY, DISTRIBUTION, DRIFT, INSHORE AREAS, LARVAE, MEAN, METAMORPHOSIS, MISSISSIPPI RIVER, NAVIGATION, PHYSICAL PROPERTIES, RIVERS, SAMPLING, SHORT RANGE(DISTANCE), STATIONS, STREAMS, SUBSTRATES, WATER, AQUATIC ORGANISMS, FRESH WATER, DIURNAL VARIATIONS, SPATIAL DISTRIBUTION

Subject Categories : Biology

Distribution Statement : APPROVED FOR PUBLIC RELEASE