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An Assessment of the Use of Seeding, Mowing, and Burning in the Restoration of an Oldfield to Tallgrass Prairie in Lewisville, Texas

Description: An examination of the effectiveness of seeding, burning, and mowing in the reestablishment of tallgrass prairie species on overgrazed and abandoned pastureland. The study site is a 20 acre tract on U.S. Corps of Engineers land below Lake Lewisville in Denton County, Texas. The site was partitioned into thirty-nine 40 by 40 meter plots with seeding (carried out in 1996) and management treatment (burning, mowing, and no maintenance carried out in 1998) randomly applied following a two level design. For each plot, nine stratified-random 0.1 m2 subplots were examined and shoot counts for each species recorded. The effects of the treatments on individual species and species richness were analyzed with a two-way ANOVA followed by a SNK multiple range test, both on ranked data. Community level analysis was conducted with both a MANOVA on ranked data and a Canonical Correspondence Analysis on raw data. Results indicate that seeding positively affected species richness, particularly when combined with either burning or mowing in the early spring. Mowing also significantly increased species richness in areas that were not seeded, while burning negatively affected species richness on unseeded plots. Treatments significantly affected community composition with treatments having the most clear effect on spring and summer forbs.
Date: August 1999
Creator: Windhager, Steven

Integration of field-based analysis of plant community dynamics with quantitative analysis of landscape change in the Ray Roberts Lake area, 1987—1997

Description: This study focused on the effectiveness of integrating traditional plant community analyses with landscape ecological analyses based on remotely sensed data. A temporal analysis of plant community diversity was conducted for major plant communities of the Ray Roberts Lake area using transect monitoring data collected between 1987 and 1997. Landscape analyses were performed with FRAGSTATS*ARC using classified SPOT satellite imagery for 1987 and 1997. Although the methodology developed in this work was exploratory, it was found that characterizing the dynamics of major plant communities in the study area produced a more effective and insightful analysis of Ray Roberts Lake area landscape dynamics.
Date: May 2000
Creator: McDonough, Theresa J.

Spatial Analysis of Atrazine in the Elm Fork Watershed

Description: This study assessed the water quality of the Elm Fork Watershed with regards to the herbicide Atrazine. Atrazine is a potential environmental endocrine disruptor and carcinogen. Overall, concentrations were lower than the four-quarter drinking water average of 3 µg/Lthe Maximum Contaminant Level set by the USEPA. However, three creek stations had four-quarter average concentrations greater than 3 µg/L, and virtually all samples exceeded the 0.1 µg/L standard set in Europe [1,2]. Statistically significant differences in concentrations were detected between the 27 sampling stations and areas of high concentrations were identified. However correlations between Atrazine concentrations and land-use and precipitation were not statistically significant. Further analysis with more detailed data should be conducted before any relationships are discarded.
Date: May 2000
Creator: Ochandio, Mario Roberto

Analysis and Development of Post Secondary Curriculum on Sustainability

Description: This thesis examines existing curricula at colleges and universities about sustainability and uses results to develop an introductory post secondary course curriculum. The proposed course is organized around three major elements - - science, philosophy, and economics - - all integral to understanding sustainability. Materials needed to teach the proposed 3-semester hour course including syllabus, teaching modules, transparencies, handouts, and exams were developed. Suggestions on how to teach a one-semester hour course on sustainability and a workshop on sustainability are also presented. The following research and curriculum development was a project established and funded by the Texas Energy Office, Renewable Resources and Sustainability Program.
Date: May 2000
Creator: White, Miki Machell

Assessing the Spatial and Temporal Distribution of MTBE and BTEX Compounds in Lake Lewisville, Texas February 1999 - February 2000

Description: The spatial and temporal distribution of Methyl Tertiary-Butyl Ether (MTBE) and BTEX (Benzene, Toluene, Ethylbenzene, Xylenes) compounds were assessed in a multipurpose reservoir, Lake Lewisville, Texas between February 1999 and February 2000. Concentrations of MTBE ranged from 0.0 - 16.7 mg/L. Levels of MTBE in the lake were related to watercraft. BTEX concentrations were never detected above 2.0 mg/L during the sampling period. Finished drinking water from Denton and the Upper Trinity Regional Water District (UTRWD) Treatment Plants were also tested for MTBE and BTEX. MTBE and BTEX were not detected in UTRWD water samples. Denton's finished water samples never exceeded 2.2 mg/L for MTBE and BTEX was not detected except for one replicate of 1.1 mg/L toluene.
Date: August 2000
Creator: Lee, Anne W.

Use of Automated Sampler to Characterize Urban Stormwater Runoff in Pecan Creek

Description: The purpose of this study was to use the Global Water Stormwater Sampler SS201 to characterize the urban runoff in Pecan Creek. Location of the samplers was influenced by land use and ease of installation. Determination of the constituents for analysis was modeled after those used in the NPDES permit for seven cities within the Dallas/Ft.Worth metroplex. Some metals, notably cadmium and arsenic, exceeded the U.S. EPA's MCL's. Statistical analysis revealed first flush samples to be significantly more concentrated than composite samples. Minimum discharge loadings were found to be significantly lower than maximum discharge loadings. Additionally there were significant differences of specific constituents between station locations and storm events.
Date: December 2000
Creator: Appel, Patrick L.

Assessment of the Efficacy of a Constructed Wetland to Reduce or Remove Wastewater Effluent Estrogenicity and Toxicity Using Biomarkers in Male Fathead Minnows (Pimephales Promelas Rafinesque, 1820)

Description: Vitellogenin in Pimephales promelas was used to assess estrogenicity of a local municipal effluent. Vitellogenin induction in male P. promelas increased in frequency and magnitude with increased exposure duration and was greater ("=0.05) than controls after 2 and 3 weeks of exposure. The level of vitellogenesis induced by effluent exposure was high compared to similar studies. A spring season evaluation followed. Biomarkers in P. promelas were used to assess the efficacy of a treatment wetland to remove toxicity and estrogenicity in final treated wastewater effluent. Comparisons were made with an effluent dominated stream and laboratory controls. Vitellogenin, GSIs (gonado-somatic indices), HSIs (hepato-somatic indices) and secondary sexual characteristics were biomarkers used in P. promelas models to assess aqueous estrogenicity. Biological indicators used to assess general fish health included hematocrit and condition factors. The estrogenic nature of the effluent was screened, concurrent with fish exposure, with GC/MS analysis for target estrogenic compounds including: 17-b estradiol, estrone, ethynylestradiol, Bisphenol A, nonylphenolic compounds, phthalates, and DDT. Plasma vitellogenin measured in P. promelas was significantly elevated (p < 0.0001) at the inflow site of the wetland and stream sites. GSIs for these exposures were less (a=0.001) at the wetland inflow site. At wetland sites closest to the inflow, secondary sexual charateristics, tubercle numbers and fat pad thickness, were less (a=0.0001). Hematocrit and condition factors were less (a=0.001) at sites closer to the wetland inflow. Seasonal variation was examined by repeating the effluent characterization in summer. Additionally, summer testing included exposure to an effluent dilution series. Fish condition heavily influenced interpretation of the results. Pre-acclimation exposure to spawning stresses may have altered many of the biological markers measured. Results are discussed relative to fish health and pre-exposure environment. Toxicity assessed with P. promelas biomarkers was compared with Ceriodaphnia dubia and Vibrio fischeri toxicty tests on this ...
Date: December 2000
Creator: Hemming, Jon M.

Thresholds in avian communities at multiple scales: Relationships between birds, forests, habitats, and landscapes in the Ray Roberts greenbelt, Denton

Description: Environmental management agencies make efforts to reduce pollution loading in streams and rivers by promoting vegetated buffer zones between human activity and water. Most of these efforts do not mesh water quality-based buffer zone width requirements with conservation and wildlife values, specifically, the use of these riparian forest corridors for wildlife dispersal between habitats in highly fragmented landscapes. Forest interior birds are of the most concern to management in riparian forests due to their population declines across much of their breeding range. This dissertation investigates the role that landscape-level and habitat-level factors play on the presence of breeding birds in riparian forests, particularly the landscape and habitat factors that are influenced by human-caused fragmentation. This study describes research at the Ray Roberts Greenbelt, Denton, Texas, that explores the relationships between the landscape and forest habitats of the Greenbelt with its breeding bird community. The major findings of this study are that bird communities in the corridor forests are associated with a greater array of factors than are bird communities in patches, suggesting that the birds of patch forests are somewhat insulated from landscape-scale effects. Also, habitat values can be maintained in corridors, but there does not seem to be a significant relationship between the bird communities and the habitat. Forest factors are the primary influences (as inferred from the number of associations and the relative strength of these associations) on the bird communities of the Ray Roberts Greenbelt. Thresholds of richness or abundance in the amount of forest as compared with the forest interior bird community suggest that patches are better than corridors to support this community, and that the more interior forest available, the better for forest interior birds. The suggested minimum amount of forest derived from these thresholds is 35% of the amount of forest within 1 kilometer ...
Date: December 2000
Creator: Barry, Dwight

Establishment and Competitive Ability of Nelumbo Lutea in Relation to Myriophyllum Spicatum

Description: Limitations from reduced light and increasing water depth on Nelumbo lutea seedlings were determined in tank experiments. Survival was high in all tested light levels. Total biomass increased significantly with increasing light. Biomass allocation shifted significantly to root production between 3 and 6 weeks in the 10 and 24% levels. Survival decreased with increasing planting depth, and biomass of survivors reduced significantly between 0.5, 1.0, and 1.5 m depths. Nelumbo lutea and Myriophyllum spicatum populations were monitored for one season in a 0.7 ha pond to track changes in species dominance. Myriophyllum spicatum dominated early, and N. lutea dominated from July through October, suppressing M. spicatum at all depths. Competitive interactions between N. lutea and M. spicatum were investigated for two seasons in a container experiment situated within a pond. Where established, N. lutea dominated in the presence of M. spicatum. However, N. lutea could not be established in depths greater than 1 meter.
Date: December 2000
Creator: Snow, Joe R.

Evaluation of the Chlorophyll/Fluorescence Sensor of the YSI Multiprobe: Comparison to an Acetone Extraction Procedure

Description: The purpose of this study was to examine the suitability of the YSI model 6600 Environmental Monitoring System (multiprobe) for long term deployment at a site in Lewisville Lake, Texas. Specifically, agreement between a laboratory extraction procedure and the multiprobe chlorophyll/fluorescence readings was examined. Preliminary studies involved determining the best method for disrupting algal cells prior to analysis and examining the precision and linearity of the acetone extraction procedure. Cell disruption by mortar and pestle grinding was preferable to bath sonication. Comparison of the chlorophyll/fluorescence readings from the multiprobe and the extraction procedure indicated that they were significantly correlated but temperature dependent.
Date: May 2001
Creator: Lambert, Patricia

The Last Laugh: Selected Edwardian Punch Cartoons of Edward Linley Sambourne

Description: The illustrative work of Edward Linley Sambourne for Punch magazine during the period 1901-1910 addresses a myriad of political topics prevalent during the Edwardian period in British history. This thesis examines two of those topics - Women's Suffrage and Socialism - through their artistic treatment by one of Britain's most influential periodicals. Through a study of the historical context and iconography of selected cartoons-of-the-week, one is better equipped to understand and appreciate the meaning, message, and humor in the cartoons. Chapter 1 introduces the Sambourne, Punch magazine, and the Edwardian period in general. Chapters 2 and 3 discuss four Women's Suffrage cartoons and four Socialism cartoons respectively. Chapter 4 draws conclusions regarding Sambourne's techniques as a cartoonist as well as the relationship between the text and image in his illustrations.
Date: May 2001
Creator: Larson, Alison

Selection and Use of Aquatic Vegetation by Migratory Waterfowl in North Central Texas

Description: Assessment of aquatic plant selection by waterfowl has been conducted during the winters of 1997-2000 on 49 0.2-0.79 ha research ponds in north central Texas. Ponds were categorized by dominant plant species into eight habitat types. Census with waterfowl species identification were performed to investigate impacts of aquatic vegetation and water depth on waterfowl. Eighteen waterfowl species were observed. Peak migration occurred in late December/early January. Mixed native ponds and mixed native/hydrilla ponds were the most frequently selected habitat types. The study included correlation analysis between pond water levels and waterfowl use. Full ponds received greatest use followed by half full ponds, while almost empty ponds received minimal use. Time activity budgets were conducted on waterfowl utilizing mixed native and hydrilla ponds to compare waterfowl time partitioning on native aquatic vegetation versus hydrilla. Although only minor differences were found in time budgets, social status appears to be strongly related to habitat selection. Ducks on native ponds were paired (86%), conversely no ducks on hydrilla ponds were paired. Hydrilla pond although frequently utilized, were populated by lower status birds mostly single hens.
Date: May 2001
Creator: Smith, JoEtta Kaye

Portrait of Your Stream: Development and Assessment of a Stream Ecology Program for Middle-School Student

Description: Portrait of Your Stream (POYS) is a stream ecology and student action program designed for use with middle-school students. The program is correlated with learning cycle pedagogical methods emphasizing student-centered lessons and activities in both classroom and outdoor settings. Implementation of a pilot program in the Fall semester of 1999 was used to collect formal and informal responses and data from students and teachers. Data included changes in student knowledge, skills and attitudes and were analyzed for determination of the success of program objectives and modifications to the program. The final POYS program is currently distributed and administered by the Botanical Research Institute of Texas.
Date: May 2001
Creator: Swirczynski, Brenda J.

Correspondence Between Aquatic Ecoregions and the Distribution of Fish Communities of Eastern Oklahoma

Description: I assessed fish community data collected by the Oklahoma Conservation Commission from 82 minimally impaired wadeable reference streams in eastern Oklahoma to determine whether existing aquatic ecoregions provide the best framework for spatial classification for the development of biological assessment methods and biocriteria. I used indirect ordination and classification to identify groups of sites that support similar fish communities. Although correspondence was observed between fish assemblages and three montane ecoregions, the classification system must be refined and expanded to include major drainage basins and physical habitat attributes for some areas to adequately partition variance in key measures of biological integrity. Results from canonical correspondence analysis indicated that substrate size and habitat type were the primary physical habitat variables that influenced the fish species composition and community structure.
Date: May 2001
Creator: Howell, Charles E.

Spatial and Temporal Patterns of Areal and Volumetric Phytoplankton Productivity of Lake Texoma

Description: Phytoplankton productivity of Lake Texoma was measured for one year from August 1999 to August 2000 for four stations, using the oxygen change method and laboratory incubation. Mean values of the photosynthetic parameters, PBmax and alphaB ranged from 4.86 to 46.39 mg O2.mg Chl-1.hr-1 for PBmax and 20.06 to 98.96 mg O2.mg Chl-1.E-1.m2 for alphaB. These values were in the range to be expected for a highly turbid, temperate reservoir. Estimated gross annual areal productivity ranged from 594 g C.m2.yr-1 (P.Q. = 1.2), at a station in the Washita River Zone to 753 g C.m2.yr-1 at a station in the Red River Zone, of the reservoir. Gross annual areal productivity at Station 17, in the Main Lake Zone, was 708 g C.m2.yr-1. Gross areal and volumetric productivity showed distinct seasonal variation with Photosynthetically Available Radiation (PAR) and temperature. Trophic status estimated on a station-by-station basis, using net productivity values derived from gross productivity and respiration estimates, was mesotrophic for all the stations, though one station approached eutrophy. Net productivity values ranged from 0.74 to 0.91 g C. m-2.d-1. An algal bioassay conducted at two stations in August 2000, revealed that phosphorus was most likely the nutrient limiting photosynthesis at both these stations, although the more turbid riverine station was primarily light-limited.
Date: August 2001
Creator: Baugher, Tessy

Effects of Sublethal Copper Exposure on Escape Behavior and Growth of Rana pipiens Tadpoles

Description: This research is designed to test how sublethal exposure to copper affects tadpole predator-escape behavior and how quickly tadpoles recover. After exposure, tadpoles were separated. Escape behavior was recorded for two-thirds of exposed tadpoles while one-third of the exposed population was measured weekly to determine growth and recovery. Control tadpoles were consumed within 15 minutes whereas those exposed to higher concentrations were consumed at a slower rate, which does not support the hypotheses. Although the rate of predation was lower, tadpoles exposed to higher Cu concentrations were on average, 1.47 cm in total body length. Those exposed to 0.93 mg/L averaged 0.86 cm. After being placed into clean water, treatment tadpoles recovered after 20 days.
Date: May 2002
Creator: Redick, Melinda

Bioreactor Landfill Cell Feasibility Study ' Reference to City of Denton Subtitle-D Permit #1590A Landfill

Description: The City of Denton Landfill, Permit #1590A, utilizes “Dry-Tomb” techniques for disposal and promotion of municipal solid waste stabilization, as described by the Resource Conservation and Recovery Act (RCRA) prohibition in 40 CFR. Bioreactor research suggests re-circulating leachate increases biodegradation rates and reduces long-term monitoring from fifty years to less than ten years. Current procedures that are followed at Denton's landfill, literature review and the use of the Hydrologic Evaluation of Landfill Performance (HELP) model, suggest that a bioreactor landfill cell is worthy of further research. Re-circulating leachate and augmenting it with additional liquid will increase biodegradation and the need to design and build a landfill gas collection system to capture methane for energy recovery uses.
Date: May 2002
Creator: Roberts, Elizabeth

Recovery of the Fish Population of a Municipal Wastewater Dominated, North Texas Creek After a Major Chlorine Disturbance

Description: This study evaluated the effects of a major chlorine disturbance on fish communities in Pecan creek by the City of Denton's Pecan Creek Water Reclamation Plant. Fish communities in Pecan Creek were sampled using a depletion methodology during February, April, July, and November, 1999. February and April sampling events showed that the fish communities were severely impacted by the chlorine. Sampling during July and November showed fish communities recovered in Pecan Creek. The first-twenty minutes of shocking and seining data were analyzed to mirror an equal effort methodology. This methodology was compared to the depletion methodology to see if the equal effort methodology could adequately monitor the recovery of Pecan Creek after the chlorine disturbance. It was determined that the equal effort methodology was capable of monitoring the recovery of Pecan Creek, but could not accurately represent the fisheries community as well as the depletion method. These data using the twenty-minute study were compared to a previous study. Results of this study were similar to those found in a previous study, although fish communities were more severely impacted and took longer to recover.
Date: August 2002
Creator: Maschmann, Gerald F.

Managing Cattail (Typha latifolia) Growth in Wetland Systems

Description: Nutrient availability, water depth, competition, and soil management effects on cattail (Typha latifolia) growth in wetland systems were examined. Soluble reactive phosphorous (SRP), nitrate-nitrogen (NO3-N), and ammonia-nitrogen (NH3-N) removals were tested at a constructed wetland receiving municipal wastewater effluent. Over all, no significant differences in nutrients occurred between diverse planted and cattail areas. T. latifolia seeds, under the canopy of Eleochoris macrostachya, had low seed germination. Established stands of emergent vegetation can prevent cattail colonization and spread. Germination of T. latifolia at various water depths was tested, and depth impacts on cattail seedling growth and survival were ascertained using various moist soil management techniques in three ponds. Water levels at 0cm and >40cm can adversely impact cattail establishment.
Date: August 2002
Creator: Sharp, Jessica Little

Water Quality Aspects of an Intermittent Stream and Backwaters in an Urban North Texas Watershed

Description: Pecan Creek flows southeast through the City of Denton, Texas. Characterized as an urban watershed, the basin covers approximately 63.5 km2. Pecan Creek is an intermittent stream that receives nonpoint runoff from urban landuses, and the City of Denton's wastewater treatment plant, Pecan Creek Water Reclamation Plant, discharges effluent to the stream. Downstream from the City of Denton and the wastewater treatment plant, Pecan Creek flows about 6,000 m through agricultural, pasture, and forested landscapes into Copas Cove of Lake Lewisville, creating backwater conditions. Pecan Creek water quality and chemistry were monitored from August 1997 to October 2001. Water quality was influenced by seasonal, spatial, climatic, and diurnal dynamics. Wastewater effluent discharged from the Pecan Creek Water Reclamation Plant had the greatest influence on water quality of the stream and backwaters. Water quality monitoring of Pecan Creek demonstrated that dissolved oxygen standards for the protection of aquatic life were being achieved. Water quality modeling of Pecan Creek was completed to assess future increases in effluent flow from the Pecan Creek Water Reclamation Plant. Water quality modeling indicated that dissolved oxygen standards would not be achieved at the future effluent flow of 21 MGD and at NPDES permitted loadings. Model results with application of a safety factor indicated that the maximum allowable concentrations for a 21 MGD discharge would be 2.3 mg/L of ammonia and 7.0 mg/L of biochemical oxygen demand at summer conditions. Drought conditions that occurred from 1998 to 2001 reduced water levels in Lake Lewisville and impacted dissolved oxygen water quality in Pecan Creek. Water quality observations made during the period of drought allowed for the development of a model to estimate the zone of the dissolved oxygen sag in Pecan Creek based on reservoir elevation. Finally, monitoring results were analyzed with nonparametric statistical procedures to detect water ...
Date: August 2002
Creator: Taylor, Ritchie Don

Use of geographic information systems for assessing ground water pollution potential by pesticides in central Thailand

Description: This study employed geographic information systems (GIS) technology to evaluate the vulnerability of groundwater to pesticide pollution. The study area included three provinces (namely, Kanchana Buri, Ratcha Buri, and Suphan Buri) located in the western part of central Thailand. Factors used for this purpose were soil texture, percent slope, primary land use, well depth, and monthly variance of rainfall. These factors were reclassified to a common scale showing potential to cause groundwater contamination by pesticides. This scale ranged from 5 to 1 which means high to low pollution potential. Also, each factor was assigned a weight indicating its influence on the movement of pesticides to groundwater. Well depth, the most important factor in this study, had the highest weight of 0.60 while each of the remaining factors had an equal weight of 0.10. These factors were superimposed by a method called “arithmetic overlay” to yield a composite vulnerability map of the study area. Maps showing relative vulnerability of groundwater to contamination by pesticides were produced. Each of them represented the degree of susceptibility of groundwater to be polluted by the following pesticides: 2,4-D, atrazine, carbofuran, dicofol, endosulfan, dieldrin & aldrin, endrin, heptachlor & heptachlor epoxide, total BHC, and total DDT. These maps were compared to groundwater quality data derived from actual observations. However, only the vulnerability maps of atrazine, endosulfan, total BHC, and heptachlor & heptachlor epoxide showed the best approximation to actual data. It was found that about 7 to 8%, 83 to 88% and 4.9 to 8.7% of the study area were highly, moderately, and lowly susceptible to pesticide pollution in groundwater, respectively. In this study a vulnerability model was developed, which is expressed as follow: V = 0.60CW + 0.10CS + 0.10CR + 0.10CL + 0.10CSL. Its function is to calculate a vulnerability score for a certain ...
Date: August 2002
Creator: Thapinta, Anat

Landscape forest modeling of the Luquillo Experimental Forest, Puerto Rico.

Description: This thesis contributes to modeling the dynamics of forest community response to environmental gradients and disturbances over a mountain landscape. A gap model (FACET) was parameterized for species of various forest types (Tabonuco, Colorado, Dwarf and Palm), for many terrain conditions and was modified and extended to include species response to excess soil moisture and hurricanes. Landscape cover types were defined by dominance of species of each forest type and canopy height. Parameters of the landscape model (MOSAIC) were calculated from multiple runs of FACET. These runs were determined by combining terrain variables (elevation and soil) and hurricane risk. MOSAIC runs were analyzed for distribution patterns. Geographic Information Systems software was used to process terrain variables, hurricane risk and MOSAIC model output.
Date: December 2002
Creator: Abbott-Wood, Chris

Ecotoxicological Investigations in Effluent-Dominated Stream Mesocosms

Description: The University of North Texas Stream Research Facility (UNTSRF) was designed to examine contaminant impacts on effluent-dominated stream ecosystems. Stream mesocosms, fed municipal effluent from the City of Denton, TX, Pecan Creek Water Reclamation Plant (PCWRP), were treated with 0, 15 or 140 µg/L cadmium for a 10-day study in August 2000. Laboratory toxicity test and stream macroinvertebrate responses indicated that cadmium bioavailability was reduced by constituents of effluent-dominated streams. The Biotic Ligand Model (BLM) for Cd was used to predict a 48 hour Cd EC50 for Ceriodaphnia dubia of 280 µg/L in these effluent-dominated streams. This value is higher that an EC50 of 38.3 µg/L Cd and a 7-day reproduction effect level of 3.3 µg/L Cd generated for C. dubia in reconstituted laboratory hard water. These results support use of a cadmium BLM for establishing site-specific acute water quality criteria in effluent-dominated streams. Although not affected by 15 µg/L treatments, organisms accumulated Cd in 15 µg/L treated streams. Hence, over longer exposure periods, Cd accumulation may increase and a no effect level may be lower than the observed 10-day no effect level of 15 µg/L. A toxicity identification evaluation procedure was utilized with in vitro and in vivo bioassays to identify estrogenic compounds in PCWRP effluent, previously identified to seasonally induce vitellogenin (VTG) in male fathead minnows. Steroids, nonylphenol ethoxylate metabolites, and other unidentified compounds were identified as causative effluent estrogens. These findings suggest that in vivo VTG bioassays should be used to confirm in vitro Yeast Estrogen Screening assay activity when effluents are fractionated or screened for estrogenicity. A subsequent 90-day cadmium study was initiated to assess long-term effluent and cadmium effects on fish endocrine function. Juvenile fathead minnows were placed in UNTSRF pool sections of replicate streams treated with 0, 5, 20 or 80 µg/L Cd. Male ...
Date: December 2002
Creator: Brooks, Bryan W.

Water Quality Mapping on Lake Texoma USA

Description: The primary objective of this study was to develop and evaluate a system capable of rapid, continuous collection of water quality and locational data on Lake Texoma. Secondary objectives included developing monthly distribution maps for chlorophyll-a, turbidity, and specific conductivity in Lake Texoma and investigating the spatial and temporal relationships between these common water quality indicators. A modified YSI multiprobe was used to develop a system capable of surveying the lake within 4 days with samples at 330 to 400 meter intervals. Data generated with this system compared favorably with previous studies of Lake Texoma. Two sets of raster format maps were developed for the monthly distributions of chlorophyll-a, turbidity, and specific conductivity across the lake. Spatial and temporal relationships generally took the form of decreasing gradients running from the lake arms towards the Main Lake Zone in the case of chlorophyll-a and turbidity. Or, in the case of specific conductivity, a decreasing gradient from the Red River arm to the Washita River arm. All three water quality indicators were strongly influenced by river discharge levels.
Date: December 2002
Creator: Mabe, Jeffrey A.