Publications

A disturbance can be defined as 'any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or the physical environment' (Pickett and White 1985). Vegetation dynamics are a function of the temporal and spatial patterns of the disturbance regime. Natural disturbance regimes support the highest biological...

Regional equations were developed for estimating mean annual and mean seasonal runoff for natural basins in Texas. The equations, which are based on the statistical relation between streamflow and basin characteristics, use streamflow data and basin characteristics from U.S. Geological Survey streamflow-gaging stations within natural basins and with a least 8 years of data during 1961-90...

The Edwards aquifer, one of the most productive carbonate-rock aquifers in the Nation, is composed of the Kainer and Person Formations of the Edwards Group plus the overlying Georgetown Formation. Most recharge to the Edwards aquifer results from the percolation of streamflow loss and the infiltration of precipitation through porous parts of the recharge zone. Residential and commercial

The “Flood Tracking Chart for the Upper San Jacinto River Basin near Houston, Texas” can be used to track river stage and to assess flood-crest information during substantial storms. Water-surface elevation during a flood will provide emergency-response personnel, residents, and the traveling general public essential information to make informed decisions concerning conditions that...

No abstract available.

In January 2000, both the Bahamas National Trust and the Save the Manatee Club received reports of a manatee at Bullocks Harbor, Great Harbour Cay, Bahamas. Under permit with the Bahamas’ Department of Fisheries, I visited Great Harbour Cay from 25 to 27 February 2000 to make a field assessment of the manatee, interview local residents, and provide management recommendations. Detailed...

No abstract available.

A model system was characterized which may be used as an in vivo screen for effects of chemicals or environmental mixtures on sexual differentiation and development of reproductive organs and gametes. We evaluated the effects of a model environmental estrogen, ethinyl estradiol (EE2), on the d-rR strain of medaka, Oryzias latipes, using a nano-injection exposure. Gonad histopathology...

No abstract available.

Extensive research has been conducted regarding the occurrence of herbicides in the hydrologic system, their fate, and their effects on human health and the environment. Few studies, however, have considered herbicide transformation products (degradates). In this study of Iowa ground water, herbicide degradates were frequently detected. In fact, herbicide degradates were eight of the 10...

No abstract available.

Beavers are increasingly viewed as “ecological engineers,” having broad effects on physical, chemical, and biological attributes of north-temperate landscapes. We examine the influence of both local successional processes associated with beaver activity and regional geomorphic boundaries on spatial variation in fish assemblages along the Kabetogama Peninsula in Voyageurs National Park...