Digital Commons Network^™

Alternative Restoration Treatments To Maximize Growth And Survival Of Tamaulipan Thornscrub Species During Seeding Establishment, Jennifer Lynn Vela

Theses and Dissertations - UTB/UTPA

Anthropogenic activities that destroy, degrade, or fragment terrestrial ecosystems have long-lasting detrimental impacts on ecosystem function, services, and biodiversity. The Tamaulipan thornscrub ecoregion of south Texas and northeastern Mexico has sustained considerable loss, degradation, and fragmentation due land conversion for agriculture, urbanization, and introduction of invasive flora and fauna. In an attempt to restore habitat for endangered and migratory animals, United States Fish and Wildlife Service has undertaken a large-scale thornscrub revegetation effort in south Texas. The goal of this study was to develop effective restoration techniques to promote growth and survival of Tamaulipan thornscrub species during seedling establishment. Beginning …

Isolation And Characterization Of Polychlorinated Biphenyl (Pcb) Degrading Bacteria Isolated From A Pcb Contaminated Reservoir In Donna, Tx, Sergio Cepeda

Theses and Dissertations - UTB/UTPA

The Donna Irrigation System (DIS) located in Donna, Hidalgo County, TX, was confirmed to be contaminated with polychlorinated biphenyls (PCBs) in 1993 and remediation of the site will be attempted in the future. The need to isolate novel PCB degrading bacteria for bioremediation has been an active area of research in recent decades; thus, it was hypothesized that a variety of microorganisms able to degrade PCBs could be isolated from sediments taken from the DIS. Two genes of the PCB degradation pathway, bphA1 and bphC, were detected in 43 bacterial isolates grown from DIS sediments using molecular and culture-based methodology, …

Gauging Wetland Restoration Status Using Benthic-Based Structural And Functional Metrics, Claudia Alejandra Tamez

Theses and Dissertations - UTB/UTPA

Efforts to restore Bahia Grande, a 2630 hectare, historically sea grass dominated playa lake, are currently underway and describing its current ecological status is critical to recommending any future physical manipulations to the immense basin. A benthic community based study was conducted on three estuaries in Cameron County, Texas (2012 to 2013) in order to compare the polychaete community dynamics and ecosystem productivity rates of the restored basin to that of two older adjacent reference sites (i.e. South Bay and San Martin Lake) in an effort to gauge system status. All three sites were once contiguous with the Lower Laguna …

Temperature And Relative Humidity Effects On Water Loss And Hemolymph Osmolality Of Littoraria Angulifera (Lamarck, 1822), Phillip J. Rose

Theses and Dissertations - UTB/UTPA

Desiccation stress is considered to be one of the more significant determining factors that influence how organisms are distributed in the marine littoral. Gastropods living above the high tide mark, referred to as eulittoral fringe gastropods are not wetted as regularly and face unpredictable and prolonged periods of emersion. Consequently, adaptations displayed by eulittoral fringe gastropods are aimed at minimizing water loss and surviving prolonged periods of desiccation stress. Littoraria angulifera, is a tropically distributed marine eulittoral fringe gastropod. Because L. angulifera spends a majority of its time emersed there was interest in studying how the weight loss and hemolymph …

Sedimentation And Barnacle Recruitment And Growth In A Shallow Coastal Lagoon Of South Texas, John Jack Gray

Theses and Dissertations - UTB/UTPA

According to the United States Environmental Protection Agency, one of this nation’s greatest concerns to the receiving waters of an aquatic system is the impairment of water quality due to sediment transport. Thus, an aquatic system whose receiving waters are subject to unrestrained sediment transport from a spoil bank, which is an unstabilized depository for sediment acquired during a dredge, should be a concern. In this study an attempt was made to assess sedimentation and its effect on the life cycle of sessile aquatic life over a year. South Bay was chosen for the study site because it is adjacent …

A Survey Of Heavy Metals In Water, Soil And The Surrounding Plants In The Lower Rio Grande Valley, Erving W. Morelius

Theses and Dissertations - UTB/UTPA

Heavy metal pollution of the environment in recent years has become a major issue of importance for both human and environmental health. Samples were investigated for the potential pollution of the area as it is a vital produce producing area. During the study plant, soil and water samples were collected from the Donna Reservoir and Canal System to test the concentration of various heavy metals. The heavy metals tested included both potentially toxic and micronutrients in the samples which included arsenic, cadmium, chromium, copper, iron, lead, nickel and sulfur. During the study, a sixty day sampling period was used to …

The Effects Of A Red Tide, Karenia Brevis Episode On The Benthic Macroinvertebrate Communities Of South Padre Island, Texas, Liana Lerma

Theses and Dissertations - UTB/UTPA

South Padre Island, Texas has experienced increasing frequency of harmful algal blooms (Karenia brevis) since the 1900’s, many of which resulted in massive fishes kills. In addition, shorebirds and other terrestrial wildlife deaths have been linked to K. brevis blooms prompting investigations of potential pathways by which brevetoxins may be transmitted to higher trophic levels. The benthic macrofanual community inhabiting the swash zone of sandy beaches consists primarily of filter feeding invertebrates which may serve as toxin bioaccumulators to secondary consumers of both marine and terrestrial food webs. The first reported mass mortality of swash zone benthic macrofauna on the …

Trace Analysis Of Volatile Organic Compounds In The Water Of The Arroyo Colorado And The Lower Laguna Madre Utilizing E.P.A.Sw846 Method 8260, Humberto Valdez

Theses and Dissertations - UTB/UTPA

Volatile organic compounds (VOC) can cause a major environmental concern since they create a hazard to public health and the environment. This study focused on determining concentration of VOCs in Arroyo Colorado waters and the Lower Laguna Madre (LLM) utilizing GC/MS. Little is known on the concentration and composition of VOCs. Toluene was the most common VOC. Concentrations ranged from 0.0010 mg/L to 0.0039 mg/L. Analysis of a sediment pore water sample collected near the mouth of the Arroyo Colorado also detected toluene (0.0023 mg/L). This study showed that VOCs were concentrated near the county boat launch and somewhat downstream. …

Mercury Concentrations In South Texas Game Fishes, E. Anthony Reisinger

Theses and Dissertations - UTB/UTPA

Mercury (Hg) is one of the most ubiquitous and controversial metals in the world primarily due to the toxicity of the organic form of the metal, methylmercury (MeHg). MeHg is a neurotoxin at high levels, known to manifest its effects on humans primarily through consumption of certain fish and marine mammals, which tend to bioaccumulate MeHg in their tissues over time. Increased fish consumption and, thus, mercury intake in residents of coastal areas necessitates a better awareness of MeHg content in game fish species, thus the subject of this study.

Three hundred thirty-nine tissue samples were taken from 19 south …

Production Of The Subtropical Seagrass, Halodule Wrightii Aschers., In Lower Laguna Madre, Texas, Joseph L. Kowalski

Theses and Dissertations - UTB/UTPA

The autecology of shoal grass, Halodule wrightii Aschers., was studied at 1.2 m depth from June 1995 to February 1997 in Lower Laguna Madre (LLM), Texas. Halodule wrightii in LLM received about 47% surface irradiance, but otherwise displayed lower growth rates and biomass in nutrient-poor rhizosphere and water-column environments compared to H. wrightii populations in other Texas estuaries. High tissue N content and low C:N ratios belied low growth dynamics. Halodule wrightii in LLM is probably nutrient limited. A high nutrient demand by H. wrightii in a nutrient-poor environment may explain, in part, its gradual displacement by Thalassia testudinum and …

Organochlorine Pesticide Residue, Physico-Chemical, And Bacteriological Profile Of The Lower Rio Grande River Of Texas, Juan H. Gonzalez

Theses and Dissertations - UTB/UTPA

An investigation was conducted to determine if the widespread and abundant use of organochlorine pesticides in the Lower Rio Grande Valley of Texas has had any effect on the microbial flora in the water and in the bottom sediments of the Lower Rio Grande River of Texas.

Rio Grande River water and bottom sediments were cultured for microbial flora, were analyzed for pesticide residues, and the physicochemical properties of the water were determined. Samples were taken at four different sites during a ten month sampling period in 1974.

Traces of organochlorine residues were found in the water, and higher concentrations …

Coastal Vegetational Communities Of The Two Texas Barrier Islands, Boca Chica And Brazos, Baltazar Cisneros

Theses and Dissertations - UTB/UTPA

Two Texas barrier islands, Boca Chica and Brazos, have unique coastal vegetational communities that may be Influenced by several environmental factors. These environmental factors include temperature, precipitation, wind speed, sunshine exposure, day length, and dune height. The purpose of this investigation was to determine the total number of coastal plant species per station, season, and year and to consider environmental factors that may significantly affect the number and pattern of coastal species. Coverage comparison between aerial and land sampling and aerial vegetational zonation was also considered.

Results indicated the presence of 21 angiosperm families and a total of 54 species. …