Distribution of Protozoa in Subsurface Sediments of a Pristine Groundwater Study Site in Oklahoma
- 1 May 1987
- journal article
- Published by American Society for Microbiology in Applied and Environmental Microbiology
- Vol. 53 (5), 1157-63
- https://doi.org/10.1128/aem.53.5.1157-1163.1987
Abstract
Sediment core samples were obtained at a groundwater study site in Oklahoma in January and June 1985. Most-probable-number estimates showed that protozoan numbers declined steeply with depth in subsoil. Flagellates and amoebae dominated the protozoan population, which declined to a most probable number of 28 . g (dry weight) in a clay loam layer at the bottom of the unsaturated zone. Samples from a texturally variable interface zone between 3 and 4 m down also were variable in their content of protozoa. Four contiguous clay loam samples in a single core from this zone contained variable numbers of amoebae ranging from 0.2 to 44 . g (dry weight). However, a sandy clay loam layer at the bottom of the core contained a mixture of flagellates and amoebae with a combined population density of 67 . g (dry weight). A slow-growing filose amoeba was isolated from interface zone samples and was tentatively classified in a new family in the order Aconchulinida. Protozoa were not detected in the saturated zone except in a very permeable gravelly, loamy sand layer at a depth of approximately 7.5 m. Low numbers (4 to 6 . g [dry weight]) of surface-type flagellates and amoebae, as well as the filose amoeba seen in the interface zone, were observed in this layer. Acid-treated and untreated samples contained equivalent numbers of protozoa, showing that the majority of protozoa in the layer at 7.5 m and the interface zone samples were encysted. Increased numbers of bacteria also were found in the layer at 7.5 m, indicating that it was biologically more active than other saturated-zone layers. Cyanobacteria grew in illuminated samples from this layer, suggesting that it may be connected hydrologically to a nearby river.Keywords
This publication has 4 references indexed in Scilit:
- Improved Flotation Technique for Microscopy of In Situ Soil and Sediment MicroorganismsApplied and Environmental Microbiology, 1986
- Characterization of Subsurface Bacteria Associated with Two Shallow Aquifers in OklahomaApplied and Environmental Microbiology, 1985
- Computation of Most Probable NumbersApplied and Environmental Microbiology, 1983
- Practical Oil Geology . By Dorsey Hager. McGraw-Hill, New York, 1915. Pp. xii + 141; figs. 76, three being full page, and one plate. $2.00 net.Science, 1915