A Comparison of Predicted and Actual Trophic Status of Lake Ray Roberts, Texas Based on Chlorophyll A (open access)

A Comparison of Predicted and Actual Trophic Status of Lake Ray Roberts, Texas Based on Chlorophyll A

Two years before impoundment, the trophic status of Lake Ray Roberts was predicted by applying the total phosphorus input into the Organization for Economic Cooperation and Development (OECD) eutrophication model. Predicted mean summer epilimnetic (MSE) chlorophyll a of Elm Fork arm, Isle duBois arm and Main Body were in the eutrophic category of the OECD model. Observed MSE chlorophyll a two years after impoundment of Elm Fork arm, Isle duBois and Main Body had not reached their predicted means and were at the mesotrophic-eutrophic boundary of the OECD model. Six years after impoundment, observed MSE chlorophyll a for Main Body, was closer to its predicted mean and in the eutrophic category of the OECD model. Six years after impoundment, Elm Fork arm was the most productive area of Lake Ray Roberts. Observed means of chlorophyll a, total phosphates, suspended solids and turbidity were often highest in the Elm Fork arm. Wastewater effluent from Gainesville and Valley View, TX, had an impact on productivity in Elm Fork arm.
Date: May 1999
Creator: Lytle, Lili Lisa
System: The UNT Digital Library
A Survey of Landowner Attitudes Toward the Construction of Lake Ray Roberts (open access)

A Survey of Landowner Attitudes Toward the Construction of Lake Ray Roberts

Documentation of social impacts resulting from the construction of Lake Ray Roberts is to be incorporated into a two year post-impoundment study. Research objectives are to: 1) locate current residences of landowners and previous landowners who were displaced; 2) determine social impacts resulting from construction of Lake Ray Roberts; 3) document degree of satisfaction with current living conditions; 4) document landowners' degree of satisfaction associated with COE negotiations; 5) document landowners' observations. Landowners were identified by telephone and sent a mail-back questionnaire. Respondents were generally happy with current residences and communities. While courtesy and sufficient information were provided by the COE, respondents would have preferred for property settlements to be more consistent and timely.
Date: August 1991
Creator: Norris, Paula Sue
System: The UNT Digital Library
Posttraumatic Stress Disorder in Adolescents with Conduct Disorder: Pre- and Post-Treatment Comparison of Trauma Types (open access)

Posttraumatic Stress Disorder in Adolescents with Conduct Disorder: Pre- and Post-Treatment Comparison of Trauma Types

The purpose of this study was to compare pre- and post-treatment differences in posttraumatic stress disorder (PTSD) symptoms in male adolescents with conduct disorder. The Children's PTSD Inventory and the PTSD Reaction Index were used to diagnose PTSD and determine trauma type (Type I single trauma or Type II recurring trauma). Pre- and post-treatment measures included the PTSD Reaction Index, the Children's Depression Inventory, the State-Trait Anxiety Inventory, the State-Trait Anger Expression Inventory, the Dissociative Experiences Scale, and the Youth Self-Report. The six-week, biweekly group treatment included education, exposure, and cognitive elements. Primary hypotheses that the abused group would statistically differ from the non-abused group in terms of pre- and post-treatment levels of avoidance, dissociation, anger/aggression, self-destructiveness, social problems, and overall levels of PTSD symptoms, were not confirmed. Overall, group therapy participants experienced statistically significant decreases in PTSD symptoms over the course of therapy. Results are discussed in light of clinical implications, recommended cautions given the lack of a robust control group, and directions for future research.
Date: August 1997
Creator: Ovaert, Lynda B.
System: The UNT Digital Library
Habitat Evaluation Procedures at Ray Roberts Lake: an Analysis of the Relationship with Ecological Indicators and a Study of Observer and Temporal Variability (open access)

Habitat Evaluation Procedures at Ray Roberts Lake: an Analysis of the Relationship with Ecological Indicators and a Study of Observer and Temporal Variability

Habitat Evaluation Procedure data gathered at Ray Roberts Lake in 1989 and 1990 were analysed for temporal variability, observer variability and relationships between Habitat Units (HUs) and species density/diversity. observer variability within a group was analysed by cluster analysis and bootstrapping. Five out of 36 sites showed significant differences in Habitat Suitability Index (HSI) values within the group. A nonparametric Mann-Whitney test was used to analyze temporal variability. One of 6 sites showed a significant difference in HSI values between years. Using Spearman's Rank Correlation Coefficient, a correlation was found between indicator species density and HUs. No significant correlation was indicated between species diversity and HUs.
Date: December 1993
Creator: Wattrus, Jane M. (Jane Marie)
System: The UNT Digital Library