You limited your search to:

  Access Rights: Public
 Degree Discipline: Environmental Science
 Collection: UNT Theses and Dissertations
Tissue-specific Bioconcentration Factor of the Synthetic Steroid Hormone Medroxyprogesterone Acetate (Mpa) in the Common Carp, Cyprinus Carpia

Tissue-specific Bioconcentration Factor of the Synthetic Steroid Hormone Medroxyprogesterone Acetate (Mpa) in the Common Carp, Cyprinus Carpia

Date: August 2013
Creator: Steele IV, William B.
Description: Due to the wide spread occurrence of medroxyprogesterone acetate (MPA), a pharmaceutical compound, in wastewater effluent and surface waters, the objectives of this work were to determine the tissue specific uptake and bioconcentration factor (BCF) for MPA in common carp. BCFs were experimentally determined for MPA in fish using a 14-day laboratory test whereby carp where exposed to 100 μg/L of MPA for a 7-day period followed by a depuration phase in which fish were maintained in dechlorinated tap water for an additional 7 days. MPA concentrations in muscle, brain, liver and plasma were determined by liquid chromatography/mass spectrometry (LC/MS). The results from the experiment indicate that MPA can accumulate in fish, however, MPA is not considered to be bioaccumulative based on regulatory standards (BCF ≥ 1000). Although MPA has a low BCF value in common carp, this compound may cause reproductive effects in fish at environmentally relevant concentrations.
Contributing Partner: UNT Libraries
Macroinvertebrate Colonization and Assemblages Associated with Aquatic Macrophytes in a Newly Created Urban Floodway Ecosystem, Dallas, Tx

Macroinvertebrate Colonization and Assemblages Associated with Aquatic Macrophytes in a Newly Created Urban Floodway Ecosystem, Dallas, Tx

Date: August 2013
Creator: Schad, Aaron Neale
Description: A study of macroinvertebrate colonization and assemblages, including secondary productivity of the familiar bluet damselfly or Enallagma civile Hagen (Odonata: Coenagrionidae), associated with the aquatic macrophytes Heteranthera dubia (Jacq.) MacMill. (water stargrass) and Potamogeton nodosus Poir. (American pondweed) was conducted at the Dallas Floodway Extension Trinity River Project (DFE) Lower Chain of Wetlands (LCOW), Dallas, TX, from September 2010 through November 2011. Macroinvertebrate abundance, taxa richness, Simpson's index of diversity, and Simpson's evenness from the two macrophytes and from three different wetland cells of varying construction completion dates, water sources, and native aquatic vegetation establishment were analyzed along with basic water quality metrics (temperature °C, pH, dissolved oxygen mg/L, and conductivity µs/cm). E. civile nymphs were separated into five developmental classes for secondary productivity estimations between macrophytes and wetland cell types. Mean annual secondary productivity in the DFE LCOW among two macrophytes of E. civile was 1392.90 ash-free dry weight mg/m²/yr, standing stock biomass was 136.77 AFDW mg/m2/yr, cohort production / biomass (P/B) ratio was calculated to be 4.30 / yr and the annual production / biomass (P/B) ratio was 10.18 /yr.
Contributing Partner: UNT Libraries
Population Dynamics of Zebra Mussels (Dreissena Polymorpha) in a North Texas Reservoir: Implications for Invasions in the Southern United States

Population Dynamics of Zebra Mussels (Dreissena Polymorpha) in a North Texas Reservoir: Implications for Invasions in the Southern United States

Date: December 2013
Creator: Churchill, Christopher J.
Description: This dissertation has two main objectives: first, quantify the effects of environmental conditions on spatio-temporal spawning and larval dynamics of zebra mussels (Dreissena polymorpha [Pallas 1771]) in Lake Texoma, and second, quantify the effects of environmental conditions on survival, growth, and reproduction of young of the year (YOY) juvenile zebra mussels. These biological responses directly influence population establishment success and invasive spread dynamics. Reproductive output of the zebra mussel population in Lake Texoma was significantly related to water temperature and lake elevation. Annual maximum larval (veliger) density decreased significantly indicating a population crash, which was likely caused by thermal stress and variability of lake elevation. In 2011, temperatures peaked at 34.3°C and lake elevation decreased to the lowest level recorded during the previous 18 years, which desiccated a substantial number of settled mussels in littoral zones. Estimated mean date of first spawn in Lake Texoma was observed approximately 1.5 months earlier than in Lake Erie, and peak veliger densities were observed two months earlier. Veligers were observed in the deepest oxygenated water after lake stratification. During a 69-day in situ experiment during summer in Lake Texoma, age-specific mortality of zebra mussels was generally high until temperatures decreased to approximately 28°C, ...
Contributing Partner: UNT Libraries
Modeling the Effects of Chronic Toxicity of Pharmaceutical Chemicals on the Life History Strategies of Ceriodaphnia Dubia:  a Multigenerational Study

Modeling the Effects of Chronic Toxicity of Pharmaceutical Chemicals on the Life History Strategies of Ceriodaphnia Dubia: a Multigenerational Study

Date: December 2013
Creator: Lamichhane, Kiran
Description: Trace quantities of pharmaceuticals (including carbamazepine and sertraline) are continuously discharged into the environment, which causes concern among scientists and regulators regarding their potential long-term impacts on aquatic ecosystems. These compounds and their metabolites are continuously interacting with the orgranisms in various life stages, and may differentially influence development of embryo, larvae, juvenile, and adult stages. To fully understand the potential ecological risks of two candidate pharmaceutical chemicals (carbamazepine (CBZ) and sertraline (SERT)) exposure on survival, growth and reproduction of Ceriodaphnia dubia in three sucessive generations under static renewal toxicity test, a multigenerational approach was taken. Results indicate that SERT exposure showed higher sensitivity to chronic exposure to C. dubia growth and reproduction than CBZ exposure. The lowest concentration to affect fecundity and growth was at 50 µg L-1 SERT in the first two generations. These parameters become more sensitive during the third generation where the LOEC was 4.8 µg L-1. The effective concentrations (EC50) for the number of offspring per female, offspring body size, and dry weight were 17.2, 21.2, and 26.2 µg SERT L-1, respectively. Endpoints measured in this study demonstrate that chronic exposure of C. dubia to SERT leads to effects that occur at concentrations an order ...
Contributing Partner: UNT Libraries
Comparative Phyto-uptake Across Distribution Coefficients of Pharmaceutical Compounds and Aquatic Macrophytes: Carbamazepine and Amiodarone Uptake in Lemna Spp

Comparative Phyto-uptake Across Distribution Coefficients of Pharmaceutical Compounds and Aquatic Macrophytes: Carbamazepine and Amiodarone Uptake in Lemna Spp

Date: August 2013
Creator: Woodard, Jennifer Kristin
Description: Few studies have been conducted on the effectiveness of phytoremediation of pharmaceutical compounds, although the persistent and non-acutely toxic nature of many of these compounds in today's water bodies may yield an ideal application for this practice. To quantify the potential effectiveness of plant uptake, kinetic and proportional bioconcentration factors (BCFk, and BCFp, respectively) in nanograms (ng) carbamazepine and amiodarone per gram (g) wet weight plant tissue for Lemna spp. were determined utilizing a 14-day continuous flow-through study. Samples were analyzed using isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) running in positive ion mode. Kinetic BCF was estimated at 0.538, while proportional BCF was estimated at 0.485. Kinetic BCF for the amiodarone study was estimated at 23.033, whereas proportional BCF was estimated at 41.340. Possible contamination of the C18 column and peristaltic pump failure may have impacted uptake results. In light of variability and current lack of research in the field, this work should be considered exploratory rather than conclusive.
Contributing Partner: UNT Libraries
Quantifying Forest Vertical Structure to Determine Bird Habitat Quality in the Greenbelt Corridor, Denton, Tx

Quantifying Forest Vertical Structure to Determine Bird Habitat Quality in the Greenbelt Corridor, Denton, Tx

Date: August 2013
Creator: Matsubayashi, Shiho
Description: This study presents the integration of light detection and range (LiDAR) and hyperspectral remote sensing to create a three-dimensional bird habitat map in the Greenbelt Corridor of the Elm Fork of the Trinity River. This map permits to examine the relationship between forest stand structure, landscape heterogeneity, and bird community composition. A biannual bird census was conducted at this site during the breeding seasons of 2009 and 2010. Census data combined with the three-dimensional map suggest that local breeding bird abundance, community structure, and spatial distribution patterns are highly influenced by vertical heterogeneity of vegetation surface. For local breeding birds, vertical heterogeneity of canopy surface within stands, connectivity to adjacent forest patches, largest forest patch index, and habitat (vegetation) types proved to be the most influential factors to determine bird community assemblages. Results also highlight the critical role of secondary forests to increase functional connectivity of forest patches. Overall, three-dimensional habitat descriptions derived from integrated LiDAR and hyperspectral data serve as a powerful bird conservation tool that shows how the distribution of bird species relates to forest composition and structure at various scales.
Contributing Partner: UNT Libraries
Simulating Thermal and Chemical Spills in Coupled Cooling Reservoirs

Simulating Thermal and Chemical Spills in Coupled Cooling Reservoirs

Date: August 1997
Creator: Qiu, Bin
Description: Hot water discharges and potential chemical spills are factors that threaten water quality in cooling reservoirs of chemical and power plants. In this thesis, three models are used to analyze the impact of these factors in a particular case study.
Contributing Partner: UNT Libraries
A Laboratory Study of the Asiatic Clam (Corbicula fluminea Müller) as Influenced by Substrate, Food Source and Water Type

A Laboratory Study of the Asiatic Clam (Corbicula fluminea Müller) as Influenced by Substrate, Food Source and Water Type

Date: May 1995
Creator: Halbrook, Courtney (Courtney Ann)
Description: Growth of Corbicula fluminea was monitored in the laboratory. Three experiments were conducted. Experiment I utilized three substrates and one food type. Experiment II utilized three substrates and two food types. Experiments I and II were conducted to determine if substrate type or food type effected growth. Experiment III used no substrates, one food type and was conducted to determine growth response to different types of water. Clams were maintained in three substrates: sand, gravel and clay. Clams were also maintained without substrate. Growth was monitored by measuring shell length (mm) and recording the weight (mg) of clams over a period of thirty days. At the end of the test period data were evaluated for normality and homogeneity.
Contributing Partner: UNT Libraries
Evaluation of the Use of the Bivalves Ischadium recurvum Rafinesque, 1820 and Corbicula fluminea Muller, 1774 as Biological Indicators of Relative Water Quality in Terms of Growth and Upper Temperature Tolerance

Evaluation of the Use of the Bivalves Ischadium recurvum Rafinesque, 1820 and Corbicula fluminea Muller, 1774 as Biological Indicators of Relative Water Quality in Terms of Growth and Upper Temperature Tolerance

Date: December 1997
Creator: Hemming, Jon Michael
Description: Growth of mussels under laboratory conditions was examined under various food regimes in different water types and temperatures. Growth was less than would be useful as an indicator and comparisons with field exposures were of minimal value. The effects of organophosphates on bivalves were examined via toxicity tests, tissue concentration, and by controlling exposure through the use of physical constraints. Upper temperature tolerance of both bivalve species was examined with respect to different acclimation temperatures and organophosphate exposures. Deviations from control exposures occurred at some temperatures. Copper effectively lowered the mean heat coma temperatures of C. fluminea at some concentrations, however, chlorine exposures did not alter heat coma temperature.
Contributing Partner: UNT Libraries
Biotic Factors and Temperature Tolerances via Critical Thermal Methodology in Goldfish

Biotic Factors and Temperature Tolerances via Critical Thermal Methodology in Goldfish

Date: August 1999
Creator: Ford, Tiiu Kirsti, 1972-
Description: CTMinimum and CTMaximum were measured in 620 goldfish to determine if biotic factors, in particular starvation, condition factor and size, affect temperature tolerance. Twenty-eight days of starvation adversely affected both upper and lower temperature tolerance. Condition factor was related to upper but not lower temperature tolerance.
Contributing Partner: UNT Libraries
FIRST PREV 1 2 3 4 5 NEXT LAST