Search Results

Pre-impoundment Environmental Study of Ray Roberts Lake

Description: "This report presents the results of the pre-impoundment investigations" of Ray Roberts Lake. The purpose of the study is "to improve understanding of the impact of [U.S. Army Corps of Engineers] water resource projects, to provide the basis for evaluating the projects' effects on fish and wildlife resources, and to provide the opportunity for better planning and development of water resource projects and natural resource management" in the Lake Ray Roberts area, located in Denton County, Texas (p. 3).
Date: May 1988
Creator: University of North Texas. Institute of Applied Sciences.
Partner: UNT Institute of Applied Sciences

Post-impoundment Study of Ray Roberts Lake Year-Six

Description: "This report presents the results of investigations conducted six years following the impoundment of Ray Roberts Lake." The purpose of the study is "to improve understanding of the impact of [U.S. Army Corps of Engineers] water resource projects, to provide the basis for evaluating the projects' effects on fish and wildlife resources, and to provide the opportunity for better planning and development of water resource projects and natural resource management" in the Lake Ray Roberts area, located in Denton County, Texas (p. 3).
Date: December 1995
Creator: University of North Texas. Institute of Applied Sciences.
Partner: UNT Institute of Applied Sciences

Ecological Studies of the Hudson River Near Indian Point

Description: "The general purpose of [this study is] to determine the ecological responses of the [Hudson] River to various classes of potential pollutants, so that the discharge of waste heat and radionuclides from the Indian Point Power Plant can be evaluated in context with these" (p. 1).
Date: April 1971
Creator: New York University. Medical Center. Institute of Environmental Medicine.
Partner: UNT Libraries

Ultraviolet Radiation Tolerance in High Elevation Copepods from the Rocky Mountains of Colorado, USA

Description: Copepods in high elevation lakes and ponds in Colorado are exposed to significant levels of ultraviolet radiation (UV), necessitating development of UV avoidance behavior and photoprotective physiological adaptations. The copepods are brightly pigmented due to accumulation of astaxanthin, a carotenoid which has photoprotective and antioxidant properties. Astaxanthin interacts with a crustacyanin-like protein, shifting its absorbance from 473 nm (hydrophobic free form, appears red) to 632 nm (protein-bound complex, appears blue). In six sites in Colorado, habitat-specific coloration patterns related to carotenoprotein complex have been observed. The objective of this study was to determine whether pigment accumulation or carotenoprotein expression has a greater effect on resistance to UV exposure. For each site, copepod tolerance to UV was assessed by survivorship during UV exposure trials. Average UV exposure was determined for each habitat. Astaxanthin profiles were generated for copepods in each site. Ability to withstand UV exposure during exposure trials was significantly different between color morphs (p < 0.0001). Red copepods were found to tolerate 2-fold greater levels of UVB than blue or mixed copepods. Additionally, red copepods have much higher levels of total astaxanthin than blue or mixed copepods (p < 0.0001) and receive a higher daily UV dose (p < 0.0003). Diaptomid carotenoprotein sequence is not homologous with that of other crustaceans in which crustacyanin has been characterized which prevented quantification of carotenoprotein transcript expression. Overall, diaptomid color morph may be an important indicator of UV conditions in high elevation lentic ecosystems.
Date: December 2011
Creator: Hudelson, Karista
Partner: UNT Libraries

Marine Ecosystems and Global Change

Description: The ocean is a vital component of the metabolism of the Earth and plays a key role in global change. In fact, the oceans cover so much of the Earth's surface that our planet has been described as the Water Planet, and it could be argued that its most extensive ecosystems are marine. Marine ecosystems are inextricably involved in the physical, chemical, biological and societal processes of global change. It is impossible to describe and understand the Earth system without understanding the ocean, the special characteristics of the environment that it provides for life, the changes that it is undergoing and the manner in which these changes interact with the total Earth System. Understanding the functioning of marine ecosystems and how they respond to global change is also essential in order to effectively manage global marine living resources, such as fisheries. The GLOBEC project is an international response to the need to understand how global change will affect the abundance, diversity and productivity of marine populations, from zooplankton to fish, that comprise a major component of oceanic ecosystems. GLOBEC's goal is to advance our understanding of the structure and functioning of such ecosystems, their major subsystems, and responses to physical forcing so that a capability can be developed to forecast the response of marine ecosystems to global change. This volume in the IGBP Science Series, "Marine Ecosystems and Global Change", gives topical examples of the scientifi c problems that GLOBEC is tackling, the innovative approaches adopted, and some selected scientific achievements. It has been written at a time when GLOBEC is in the mid-phase of its implementation. The ultimate achievements of GLOBEC research will be presented in a final synthesis at the end of the project.
Date: 2003
Creator: Global Ocean Ecosystem Dynamics Project (GLOBEC)
Partner: UNT Libraries

Global Ocean Ecosystem Dynamics (GLOBEC) Science Plan

Description: Human population and associated industrial activities continue to increase rapidly, and have reached levels that put the environment under stress in many areas of the world. In addition natural fluctuations of the Earth's physical and biological systems, often occur in time frames that are not readily evident to man. Such fluctuations cause additional stress on the environment, and can result in changes that impact society in terms of diminished availability of clean water, unspoiled land and natural vegetation, minerals, fish stocks, and clean air. Human societies are making a rapidly increasing number of policy and management decisions that attempt to allow both for natural fluctuations and to limit or modify human impact. Such decisions are often ineffective, as a result of economic, political and social constraints, and inadequate understanding of the interactions between human activities and natural responses. Improved understanding of such issues is important in its own right, and will contribute to ameliorating economic, political and social constraints. Developing improved understanding of environmental change is within the realm of the natural sciences and is being addressed by the International Geosphere-Biosphere Programme (IGBP) and other programmes concerned with describing and understanding the Earth System. Natural variability, occurring over a variety of time scales, dominates the health of complex marine ecosystems, regardless of fishing or other environmental pressure. We are only now beginning to compile quantitative documentation of such variability, and consequently our knowledge concerning its causes remains at the level of hypotheses. Understanding of the role of variability in the functioning of marine ecosystems is essential if we are to effectively manage global marine living resources such as fisheries during this period of tremendously increased human impact, and concurrent dependence, on these resources.
Date: 1997
Creator: Global Ocean Ecosystem Dynamics (GLOBEC)
Partner: UNT Libraries

Post-impoundment Study of Ray Roberts Lake Year-Ten

Description: "This report is the final chapter of a long-term project to assess the environmental impacts associated with the construction and operation of Ray Roberts Lake during its first ten years" (p. ii). The purpose of the study is "to improve understanding of the impact of [U.S. Army Corps of Engineers] water resource projects, to provide the basis for evaluating the projects' effects on fish and wildlife resources, and to provide the opportunity for better planning and development of water resource projects and natural resource management" in the Lake Ray Roberts area, located in Denton County, Texas (p. 3).
Date: December 1999
Creator: University of North Texas. Institute of Applied Sciences.
Partner: UNT Institute of Applied Sciences

Pre-impoundment Environmental Study of Ray Roberts Lake

Description: "This report presents the results of the pre-impoundment investigations" of Ray Roberts Lake. The purpose of the study is "to improve understanding of the impact of [U.S. Army Corps of Engineers] water resource projects, to provide the basis for evaluating the projects' effects on fish and wildlife resources, and to provide the opportunity for better planning and development of water resource projects and natural resource management" in the Lake Ray Roberts area, located in Denton County, Texas (p. 3).
Date: December 1987
Creator: University of North Texas. Institute of Applied Sciences.
Partner: UNT Institute of Applied Sciences

Spatial and Temporal Influences of Water Quality on Zooplankton in Lake Texoma

Description: Seventy-one aquatic species including the copepodids and nauplii were identified from Lake Texoma from August 1996 to September 1997. Zooplankton community structure, abundance and spatial and temporal distributions were compared among five lake zones delineated a priori based on chloride concentration. The zones, in order of decreasing chloride concentration, are the Red River zone (RRZ), Red river Transition zone (RRTZ), Main Lake zone (MLZ), Washita River Transition zone (WRTZ) and Washita River zone (WRZ). Bray Curtis Similarity Index showed community structure was most similar in the two Red River arm zones, the two Washita River arm zones and the MLZ. Zooplankton abundance was greatest in the Red River arm (312 org/L), intermediate in the Washita River arm (217 org/L) and least in the Main Lake body (103 org/L). A significant increase in the abundance of a deformed rotifer, Keratella cochlearis, was observed mainly in the Red River arm during a second study from March 1999 to June 1999. Seasonal dynamics, rather than spatial dynamics, were more important in structuring the zooplankton community, especially in the two river arms. Spatial variance was solely attributed to station and zone effects independent of time for a few crustacean species and many of the water quality parameters supporting the presence of longitudinal gradients of differing water quality. Three independent models (Red River arm, Washita River arm, Main Lake body) rather than a single model for the entire reservoir, best describe patterns in the zooplankton community and its relationship to seasonal, physical and chemical factors. Statistical power, sample size and taxonomic resolution were examined. When monitoring seasonal and annuals trends in abundance, the greatest statistical power was achieved by analyzing count data at taxonomic levels above genus. Taxonomic sufficiency was assessed to determine if costs could be reduced for zooplankton identifications. For water quality monitoring ...
Date: May 2000
Creator: Franks, Jessica L.
Partner: UNT Libraries

Seasonal and Spatial Variability of the Microcrustacean Community in Lake Texoma, Texas and Oklahoma

Description: Twenty-eight species of zooplankton were identified from Lake Texoma. Seasonal density of the overall microcrustacean community and seasonal cycles of individual species were compared with northern populations and any available literature from the Southwest. Cycles of occurrence and abundance were similar to those observed in northern populations but tended to occur earlier in the year due to higher temperatures. Spatial distributions within the reservoir were heavily influenced by nutrient and salt input from the Red River, which resulted in dense populations in the Red River Arm. In addition, during the summer, the microcrustacean community was restricted to the epilimnion due to anoxic conditions in the hypolimnion of the reservoir.
Date: August 1980
Creator: Crist, Lawrence W.
Partner: UNT Libraries