Publications

Communities of submerged aquatic vegetation (SAY) are important components of many freshwater, brackish, and marine aquatic ecosystems. They prevent erosion by baffling the impacts of waves, especially from storms. These aquatic plant communities remove nutrients and other pollutants from river and runoff inputs to coastal areas, preventing their entry into surrounding waters. They...

This report is one in an annual series of reports that depicts water-level altitudes and water-level changes since 1977 and compaction since 1973 in the Chicot and Evangeline aquifers in the Houston-Galveston region, Texas.

The Iowa Department of Natural Resources. Geological Survey Bureau: the University of Iowa Hygienic Laboratory; and the U.S. Geological Survey (USGS) have been working together to address this question. As part of the Iowa Ground-Water Monitoring Program (IGWM). water samples have been collected from selected Iowa municipal wells since 1982. An examination of this data identified two...

Water-surface-elevation profiles and peak discharges for the flood of July 9-11, 1993, in the Raccoon River Basin, west-central Iowa, are presented in this report. The profiles illustrate the 1993 flood along the Raccoon, North Raccoon, South Raccoon, and Middle Raccoon Rivers and along Brushy and Storm Creeks in the west-central Iowa counties of Carroll, Dallas, Greene, Guthrie, and...

Water-quality and streamflow monitoring data, collected from 1983 to 1995, were analyzed for 34 stream and reservoir sites in a seven- county region within the upper Neuse and upper Cape Fear River Basins. Early data (1983-88) were compiled from U.S. Geological Survey water- quality studies and from the ambient water-quality monitoring network of the North Carolina Department of...

The Edwards aquifer supplies drinking water for more than 1 million people in south-central Texas. The saline-water zone of the Edwards aquifer extends from the downdip limit of freshwater to the southern and eastern edge of the Stuart City Formation. Water samples from 16 wells in the Edwards aquifer saline-water zone were collected during July–September 1990 and analyzed for major and...

Drought conditions in the 1980's focused attention on the multiple uses of the surface- and ground-water resources in the Apalachicola-Chattahoochee-Flint (ACT) and Alabama-Coosa-Tallapoosa (ACT) River basins in Georgia, Alabama, and Florida. State and Federal agencies also have proposed projects that would require additional water resources and revise operating practices within the...

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Abstract not supplied at this time

We conducted laboratory experiments which demonstrated that three littoral zone fishes differentially selected among three macrophytes when seeking refuge from predation. In the presence of a predator (a juvenile Micropterus salmoides), mosquitofish (Gambusia holbrooki), sailfin mollies (Poecilia latipinna). and dollar sunfish (Lepomis marginatus) displayed ferential use of four tank...

The dynamics of interacting consumer and resource populations is one of the most thoroughly studied problems of theoretical population biology. Among the key results from the study of simple mathematical models of interacting populations is that the Holling Type 2 functional response tends to be unstable for a wide range of realistic parameters. Functional responses such as Holling Type...

Predator-prey models with a prey-dependent functional response have the property that the prey equilibrium value is determined only by predator characteristics. However, in observed natural systems (for instance, snail-periphyton interactions in streams) the equilibrium periphyton biomass has been shown experimentally to be influenced by both snail numbers and levels of available...