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Full-Text Articles in Life Sciences

Effects Of Cadmium On Juvenile Bluegill (Lepomis Macrochirus) Foraging Behavior And Growth , Michael D. Bryan Jan 1993

Effects Of Cadmium On Juvenile Bluegill (Lepomis Macrochirus) Foraging Behavior And Growth , Michael D. Bryan

Retrospective Theses and Dissertations

Standardized toxicity testing protocols for assessing chemical hazards to aquatic organisms inadequately consider behavioral effects of toxicants; yet, organisms behaving abnormally in the wild experience reduced growth, fitness, and higher mortality. This study determined the effects of cadmium (0, 30, 60, 120, and 240 [mu]g/L) on juvenile bluegill (Lepomis macrochirus) foraging behavior in three 28-d functional response experiments, and one 24-d multi-prey experiment. The study also examined how cadmium-altered behaviors contributed to reduced growth rates. Different sizes of Daphnia magna and D. pulex were used as prey in these experiments. The rate of change (i.e., trends over ...


Paired Prairie And Cultivated Soils: Soluble Organics And Nitrogen Dynamics , Thomas Henry Deluca Jan 1993

Paired Prairie And Cultivated Soils: Soluble Organics And Nitrogen Dynamics , Thomas Henry Deluca

Retrospective Theses and Dissertations

Nitrate contamination of water resources in the Midwestern U.S. is largely a result of conventional agricultural practices. In contrast, soils of prairie ecosystems do not accumulate NO[subscript]3 because of rapid NO[subscript]3 assimilation by plants and microbes. Microbial NO[subscript]3 assimilation requires a readily available C source; however, there is little known regarding available C in soils. The ability of prairie soils to recycle NO[subscript]3 makes the prairie ecosystem a useful model in N cycle studies designed to develop agricultural systems that minimize N loss;I performed field and laboratory studies on paired ...


Environmental Pollution Control Under Alternative Incentive Structures , Ramu Govindasamy Jan 1993

Environmental Pollution Control Under Alternative Incentive Structures , Ramu Govindasamy

Retrospective Theses and Dissertations

The present study examines environmental pollution control under alternative incentive structures with an emphasis on the effectiveness and practicality of alternative policy tools. The focus is on three instruments for controlling pollution: (1) Environmental Bonds; (2) Budget Balancing Incentive Mechanisms; and (3) Environmental Rank Order Tournaments;Environmental bonds typically require more information for implementation than either budget balancing incentive mechanisms or rank order tournaments. However, there is a trade-off between the cost savings from acquiring information and the potential costs from committing an error in assigning pollution control responsibility;Paper I examines the limits to environmental bonds. It identifies three ...


Effects Of Cottonseed Meal Supplementation On The Performance And Pasture Utilization By Zebu Steers , Aboubakar Njoya Jan 1993

Effects Of Cottonseed Meal Supplementation On The Performance And Pasture Utilization By Zebu Steers , Aboubakar Njoya

Retrospective Theses and Dissertations

A 2-period grazing experiment was designed to determine the effects of cottonseed meal (CSM) supplementation on forage intake (FDMI), forage digestibility (FDMD) and weight gain (ADG) of steers on a natural pasture in Sub-Saharan Africa during 120 d in the dry season and the residual effects when pasture regenerates during 120 d in the rainy season. Thirty steers (229 kg and 2.6 years) were randomly assigned to a complete block design of 3 treatments (0,.5 and 1.0 kg of CSM per steer per day). After hand-feeding CSM to individual steers in the mornings, all were allowed to ...


Aggressive Vocalizations In Feeding Guanacos, Lama Guanicoe , Bao-Sen Shieh Jan 1993

Aggressive Vocalizations In Feeding Guanacos, Lama Guanicoe , Bao-Sen Shieh

Retrospective Theses and Dissertations

Guanacos (Lama guanicoe) are highly social ungulates which exhibit subtle threat displays and aggressive vocalizations when feeding. Although studies have qualitatively described aggressive vocalizations, the causation and functional significance of aggressive vocalizations in feeding guanacos are poorly understood. In the General Introduction, I review game theory models for aggressive signals in animal conflicts. In Paper 1, I investigate the causation of aggressive vocalizations, namely, individual and contextual variations in a feeding group of guanacos. In Paper 2, I apply the optimal deceit model to the guanaco feeding group and discuss an alternative hypothesis to interpret the functional significance of aggressive ...


Fungal Contributions To Soil Aggregation And Soil Quality , Neal Samuel Eash Jan 1993

Fungal Contributions To Soil Aggregation And Soil Quality , Neal Samuel Eash

Retrospective Theses and Dissertations

Conceptual models implicate the fungi as important mechanisms in soil aggregate formation but the lack of suitable assays for routine quantification of fungal biomass make validation of these models evasive. The objectives of these studies were threefold: (1) to evaluate the effectiveness of ergosterol as an indicator of fungal biomass; (2) to evaluate interrelationships between aggregate-forming processes induced by fungi and those caused by physical and chemical factors; (3) to evaluate potential soil quality indicators under different tillage and residue management systems. Objective 1 focused on determining the efficiency of recovering ergosterol from spiked soil samples and measuring ergosterol of ...


Tradeoffs In Balancing Multiple Objectives Of An Integrated Agricultural Economic And Environmental System , P. G. Lakshminarayan Jan 1993

Tradeoffs In Balancing Multiple Objectives Of An Integrated Agricultural Economic And Environmental System , P. G. Lakshminarayan

Retrospective Theses and Dissertations

This research, which integrates the economic and environmental processes in a multiobjective framework to find comprehensive solution, is a departure from the traditional approach. The problem is motivated by multiattribute utility and social welfare theory, and the conditions for optimality are derived. Since agricultural nonpoint source pollution (NPS) pollution is a nonmarket externality, a motivation based on public policy and social costs is provided to include environmental quality decisions. A conceptual framework for integrating the multidisciplinary models is presented. The environmental data needs of the integrated system was obtained from spatially simulated predictions of the biogeophysical process model, a mathematical ...


Isolation And Identification Of Root-Inhibiting Compounds From Corn Gluten Meal , Dianna Lan-Ying Liu Jan 1993

Isolation And Identification Of Root-Inhibiting Compounds From Corn Gluten Meal , Dianna Lan-Ying Liu

Retrospective Theses and Dissertations

Public awareness and concern for environmental protection and human safety has led to the search for naturally occurring compounds that are able to inhibit growth and development of weed plants. It has been reported that corn gluten meal is useful as a natural preemergence herbicide and fertilizer material for various plant production systems. The active components responsible for the herbicidal activity of corn gluten meal could potentially be used as natural herbicides;Based on the results from greenhouse and growth chamber bioassays using three species of grass plants, it was found that samples of hydrolyzed protein from corn gluten meal ...


Sorption Kinetics Of Atrazine And Hydroxyatrazine In Freshwater Wetlands, Michael Patrick Matter Jan 1993

Sorption Kinetics Of Atrazine And Hydroxyatrazine In Freshwater Wetlands, Michael Patrick Matter

Retrospective Theses and Dissertations

No abstract provided.


The Influence Of Wetland Age On Bird And Aquatic Macroinvertebrate Use Of Restored Iowa Wetlands , Kristin Leigh Vanrees-Siewert Jan 1993

The Influence Of Wetland Age On Bird And Aquatic Macroinvertebrate Use Of Restored Iowa Wetlands , Kristin Leigh Vanrees-Siewert

Retrospective Theses and Dissertations

Restoration of damaged, lost, and fragmented natural ecosystems is a goal of many public and private conservation organizations, and has become an increasing part of natural resource management. Restoration of wetland habitats has received considerable interest due in part to the dramatic loss of wetland habitat (Dahl 1990), regional decline of waterfowl populations, financial incentives for private landowners to restore former wetland basins (Wetlands Reserve Programs, conservation Reserve Program), and heightened public awareness of wetland functions and values. More than 10,000 drained basins in the Prairie Pothole region of the united states have been restored to wetland conditions since ...