Life Sciences Commons^™

Effect Of Elevated Temperature And Roundup Exposure On Oxidative Stress And Antioxidant Status In The American Oyster, Afsana Chowdhury

Theses and Dissertations

Aquatic organisms are frequently exposed to various environmental stressors. In this study, we observed the short-term (1-week) combined dose-dependent effect of Roundup, a glyphosate-based herbicide, and high temperature (30°C) on the morphology of gills and digestive glands, expression of heat shock protein-70 (HSP70), dinitrophenyl protein (DNP), nitrotyrosine protein (NTP), antioxidant enzymes such as catalase (CAT) and superoxidase dismutase (SOD) in tissues of American oyster (Crassostrea virginica). Histological analyses showed an increase in mucous production in the gills and digestive glands, hemocyte aggregation in the connective tissues as well as structural change of the lumen in the digestive glands …

South Texas Wildlife Activity Across A Fragmented Landscape And Road Mitigation Corridor, Caitlin K. Brett

Theses and Dissertations

Wildlife crossing structures (WCS) and roadside fencing are commonly installed to mitigate habitat fragmentation, wildlife road mortalities, and other negative effects that roads can have on the surrounding landscape. Eight such WCS were constructed below Farm-to-Market (FM)106 in Cameron County, Texas, across a 16 km corridor transecting the Laguna Atascosa National Wildlife Refuge. These WCS, paired with adjacent roadside fencing, were intended to prevent road mortalities of the endangered ocelot (Leopardus pardalis) and to mitigate the barrier effect of FM106 on this and other meso-mammal species. This study will analyze camera trap data from roadside and habitat reference …

Influence Of Pretreatments On Physiological Status And Post-Planting Survival Of Thornforest Seedlings In A Restoration Context, Douglas E. Mainhart

Theses and Dissertations

Semi-arid ecosystems across the globe have faced land conversion posing a threat to the important ecosystem services they provide. Revegetation-centered restoration efforts in arid regions have low success due to limited water availability and higher temperatures. Typically, practitioners utilize methods that modify field conditions around seedlings to mitigate these stressors. I evaluated the efficacy of in-nursery treatments to improve plant water status. Three pretreatments were applied: elevated CO2, drought hardening, and an antitranspirant foliar spray. My goal was to understand how these pretreatments would impact survival and growth in the field and what physiological traits they altered. Elevated CO2 and …

Incorporating Native Plants In Insectary Strips To Promote Insect Diversity And Below-Ground Beneficial Microbes In South Texas, Lindsey N. Richards

Theses and Dissertations

Farm edges are generally the most undisturbed areas in a farm with diverse vegetation and can enhance agrobiodiversity and provide crucial food and shelter for wildlife, insects, and soil biota. Planting native wildflowers with the ability to reseed and withstand local climatic conditions for semi-permanent vegetation around farm edges or in between crops has potential to biologically control pests. To test this, we ran a two-year study and installed three different flowering insectary strips on a certified organic vegetable farm in South Texas during the winter season. The treatments were: 1) a commercially sourced 17-species native wildflower seed mix; 2) …

Weather Parameters Influencing The Incidence Of Citrus Canker Caused By Aw Strain In The Rio Grande Valley, Amit Sharma

Theses and Dissertations

Citrus canker caused by bacterium Xanthomonas citri subsp. citri (Xcc) seriously affects the citrus industry by making the fruit unmarketable due to unsightly lesions on the fruit. Canker caused by Aw strain of Xcc was reported in the citrus trees located in the residential areas of the Rio Grande Valley (RGV). Canker severity differs amongst cultivars/varieties, and it is influenced by prevailing environmental conditions. Multiple regression modeling of the disease incidence with the environmental variables such as temperature, humidity, windspeed, wind gust, and rainfall was performed to understand the environmental conditions that are favorable for spread of citrus …

Tree Ring Reconstructions Of Streamflow For The Lower Rio Grande Valley Of Texas, Adedolapo Mutiyat Adeyanju

Theses and Dissertations

The Rio Grande River is a major water source for people living within the USA-Mexico border. The Rio Grande River has its headwaters in the San Juan Mountains in Colorado and the Sierra Madre Occidental in Mexico before flowing into Texas through El-Paso. The water supply issues facing the Lower Rio Grande Basin (LRGB) are extremely complex from international restrictions to severe climate change. The river shares its flow between the U.S.A and Mexico based on the provisions of the 1944 treaty between the U.S.A and Mexico. The LRGB flow is regulated by releases from Falcon and Amistad Reservoirs managed …

Quantifying And Predicting Drought Performance In Woody Semi-Arid Seedlings In South Texas: Implications For Enhancing Drought Resilience In Restoration, Zarek Contreras

Theses and Dissertations

Increasingly frequent and severe droughts in the Lower Rio Grande Valley National Wildlife Refuge have been observed to cause large variation in species-specific mortality patterns in young seedlings, spanning 6 – 43 % mortality within the first year. To understand the underlying mechanisms behind this, we subjected seedlings of five woody semi-arid species (Celtis pallida, Forestiera angustifolia, Sideroxylon celastrinum, Phaulothalmnus spinescens, and Zanthoxylum fagara) to a point-of-no-return drought experiment in order to (1) identify potential metrics capable of predicting species wilting and mortality responses, and (2) to understand the underlying mechanisms that correspond to species drought performance …

Removal Of Arsenic (Iii) And Arsenic (V) From Aqueous Solution Via Common Sunflower Helianthus Annuus By Phytoremediation, Irving A. Vazquez Hurtado

Theses and Dissertations

Phytoremediation provides a cost-effective, non-invasive technique to remove contaminants from the soil and groundwater. Sunflowers are fast growing and have a showed effective at removing various pollutants from soil, including lead and other heavy metals. Health issues related to arsenic are mainly attributed to exposure of arsenite, whereas arsenate is much less toxic. The common sunflower Helianthus annuus was the species used to remove both arsenic (III) and As(V) ions from hydroponics solutions. In the present study sunflower seeds were germinated for a week, placed under the sun for a day and subsequently placed in a nutrient solution to aid …

Growth Kinetics Of Salmonella Spp. During Post-Harvest Storage Of Fresh And Fresh-Cut Papaya, Amandeep Singh

Theses and Dissertations

Fresh produce safety is major concern in United States. Fresh produce has been associated with numerous food-borne outbreaks each year. Salmonella has been a recurring issue in the papaya industry. Since 2010, imported papayas have been implicated in 8 multistate outbreaks associated with Salmonella spp. causing 480 illnesses, 113 hospitalization and 3 deaths. The main reason behind this problem is as fresh papaya is grown on fields where they are constantly exposed to preharvest microbial contamination through contaminated irrigation water, agricultural soil, raw manure and/or feces deposited by intruding domestic or wild animals. Moreover, majority fresh papaya is also consumed …

Biochar Applications To The Remediation Of Lead And Polychlorinated Biphenyl Contaminated Water, Victory Itua Igberase

Theses and Dissertations

This study investigated the performance of biochar materials as adsorbents to remove Pb and polychlorinated biphenyl (PCB) in aqueous solutions. Batch adsorption and column experiment packed with biochar and geomaterials (pumice) in 1:1 volume ratio was evaluated to address the efficacy of biochar in removing Pb while only batch adsorption was employed for PCB removal with biochar materials. Overall, PT biochars performed the best (42–53 mg g−1) followed by BE biochars (10–32 mg g−1) and AB biochars (17–27 mg g−1) while high temperature biochars were favored in terms of maximum Pb adsorption capacity. Column Pb breakthrough showed similar results, with …

Practical Challenges Of Using Sunn Hemp As A Cover Crop In The Lower Rio Grande Valley, Qulina Rai

Theses and Dissertations

Sunn hemp (Crotalaria junceae) is an emerging cover crop with many reported benefits such as nitrogen fixation, carbon sequestration, and suppression of weeds and nematodes. Relatively little is known about appropriate ways to inoculate sunn hemp ensuring nitrogen fixation, and diseases that affect sunn hemp within the Lower Rio Grande Valley of Texas.

Four sticking agents, peanut oil, jaggery, gum arabic, and water used to aid inoculation of Bradyrhizobium japonicum in sunn hemp was checked on nodulation. Water treatment was least effective. Peanut oil and jaggery treatment showed better performance in overall total nodules, and active nodules. Gum …

Influence Of Landscape Factors On Wildlife Presence And Road Mitigation Structure Performance, Taylor M. Hopkins

Theses and Dissertations

There are roughly 80 ocelots (Leopardus pardalis) remaining in the United States, with the entire population constrained to south Texas, with roadkill being a predominant source of mortality. To prevent additional roadkill and maintain wildlife movement, Texas Department of Transportation constructed 11.9 kilometers of wildlife exclusion fencing, 5 wildlife crossing structures (WCS), and 18 wildlife guards on State Highway 100. This thesis focused on determining the effort required for a control-impact monitoring study, the influence of biotic and abiotic factors around the roadway on wildlife presence, and the performance of mitigation structures and the road mitigation corridor. This …

The Application Of Advanced Technologies For Agriculture And Rangeland Management, Matthew D. Kutugata

Theses and Dissertations

This project demonstrates two applications of remote sensing in agricultural and rangeland environments. In the first, an unmanned aerial system (UAS) equipped with a multi-spectral sensor was used to estimate canopy cover across four different cover crop trials at four time periods. In the second, a local database of stationary camera trap images of wildlife was used to train a convolutional neural network to automatically catalogue images by identifying the animal in those images. Both projects aimed to provide an example of how remote sensing platforms and machine learning techniques can facilitate the rapid collection and processing of large-scale field …

The Influence Of Human Disturbance On Wildlife Use Of A Highway In South Texas, Thomas J. Yamashita

Theses and Dissertations

Roads can greatly impact wildlife. Wildlife vehicle collisions contribute to population declines while disturbance from human activity may prevent wildlife from using areas around roads. The construction of mitigation structures may lessen these effects through fine scale modification of animal use of roadside areas. In this thesis, how the construction of wildlife mitigation structures impacted the fine scale distribution of wildlife on State Highway 100 in Cameron County, Texas was examined. Spatial and temporal scale may also influence these relationships. The relationship between human activity and wildlife activity around the highway was explored and how the distribution of wildlife road …

Analysis Of The Facilitative Interaction Between Batis Maritima And Avicennia Germinans As A Mangrove Restoration Strategy, Javier R. Navarro

Theses and Dissertations

The multiple experiments conducted in an Avicennia germinans forest in Laguna Vista, TX was focused on determining if facilitation theory could explain the behavior observed between the herbaceous halophyte Batis maritima and A. germinans. I hypnotized that a positive interaction exists but through which mechanisms of facilitation I did not know. The overarching theme of the study is the presence or absence of B. maritima. Facilitation theory tells us that positive interactions are most often found under stressful conditions such as those on the coastal tidal flat of the Laguna Madre. Locally B. maritima has been found to …

Wildlife Use Of Road Mitigation Structures In Relation To Their Construction, Structural Characteristics, And Environmental Factors Along A South Texas Highway, Anna D. Rivera Roy

Theses and Dissertations

Roads are known to negatively impact wildlife by fragmenting habitat and mortality caused by wildlife-vehicle collisions. Road mitigation structures, such as wildlife crossing structures (WCS), wildlife guards (WG), and fencing are commonly used to address the issue of roads. In South Texas, such structures were built or modified along State Highway (SH) 100 in Cameron County as an effort to conserve the endangered ocelot (Leopardus pardalis). Camera traps were deployed to monitor these structures as a way to assess their effectiveness in restricting wildlife entry into the roadway with fencing and WG and conveying wildlife movement across roads …

Survival Of Off-Host Rhipicephalus (Boophilus) Annulatus (Acari: Ixodidae) Larvae In Study Arenas In Relation To Climatic Factors And Habitats In South Texas, Usa, Emily Jesselle Zamora

Theses and Dissertations

The cattle fever tick, Rhipicephalus (Boophilus) annulatus (Say), is an economically destructive arthropod because of its ability to vector bovine babesiosis. Cattle fever ticks can spend more than 90% of their life cycle as questing larvae, but the effect of climatic factors on their off-host behavior and survival is unclear. The goal of this study was to measure the effects of specific ecological factors on off-host larvae in nature. The study was conducted in a south Texas pasture over a 20-mo period, during which time larval populations were surveyed and ambient weather variables - relative humidity and temperatures – were …

Viability Of Wetland Crops For Use In Treatment Wetlands: Nitrogen Removal From Water And Production Of Food, Andrew Denson Corder

Theses and Dissertations

Treatment wetlands are used to treat wastewater from a variety of sources, but their functionality depends on the macrophytes present therein. To better understand the viability of wetland macrophytes both as sources of food and as agents of nitrogen removal from wastewater, this study quantified plant growth, food production, and nitrogen removal capacity of three common wetland crops as well as three locally dominant graminoid species in a variety of relevant ecological contexts. All six plant species and a control were grown over a ten-week period in three related experiments: (1) under three moisture regimes, (2) with or without competition …

Histological Evidence Of Annual And Lunar Reproductive Rhythms Of Atlantic Sea Urchin, Arbacia Punctulata In The Gulf Of Mexico: Changes In Nutritive Phagocytes In Relation To Gametogenesis, Eleazar Hernandez Ii

Theses and Dissertations

Environmental phenomena such as temperature, photoperiod, tidal cycle, and lunar rhythm act as external cues that stimulate the reproductive activity of marine organisms. In this study, I report the annual and lunar reproductive cycles, and changes in nutritive phagocytes (NPs) in relation to gonadal maturation of Atlantic sea urchin (Arbacia punctulata, a primeval species). Monthly and weekly changes in gonadal development/maturation were observed histologically. In male, the testicular lobules were densely packed with sperm from June to August. In female, on the other hand, mature eggs first appeared in some ovaries in May, numerically increased from June to …

A Landscape-Scaled And Community Ecology Approach To Wildlife Corridor Design In South Texas, James A. Stilley

Theses and Dissertations

A formidable challenge in landscape ecology is developing a sound resolution to mitigate the impacts of habitat fragmentation and restore connectivity to a degraded landscape. The problem is worldwide landscapes are becoming primarily anthropogenic and areas set aside for wildlife are small and isolated. Researchers’ have developed the concept of the wildlife corridor to mediate this situation but a proper methodology to implement this concept is still in its infancy. This study aims to uncover a quantitative and repeatable wildlife corridor design methodology based on the least cost analysis strategy with both a singular focal taxa approach and a comprehensive …

Evaluating Responses Of Benthic Macrofauna To Artificial Reef Presence In The Gulf Of Mexico, Douglas Faircloth

Theses and Dissertations

Artificial reef research has long concerned itself with the interactions of fishes and has tended to favor commercially valuable species. Because of this, a larger yet less known group that heavily benefits fishes have been overlooked; benthic macrofauna. Benthic macrofauna are marine invertebrates that live below the sediment-water interface and play many roles in the ecosystem. Macrofauna are important prey items, ecosystem engineers, and bioindicators, as well as being ubiquitous in the marine environment. Since macrofauna have been largely ignored in this field, not much is known regarding their interaction with the placement of artificial reefs. To try and fill …

Developing Multispectral Imaging Techniques To Determine Canopy Coverage And Carbon Storage Of Seagrasses In The Gulf Of Mexico, Ivy Michelle Hinson

Theses and Dissertations

Although seagrass beds provide global ecosystem services, coverage is in rapid decline, with the capacity of seagrasses to sequester carbon of special concern. Current seagrass monitoring methods are labor intensive and may not offer a complete picture of coverage. Remote sensing offers the ability to oversee landscapes but water in coastal environments presents challenges, as the commonly used near-infrared wavelength dissipates in water.

This project aimed to provide reliable methodology to assess seagrass coverage using multispectral imagery taken from an unmanned aerial vehicle and to provide evidence for the link between seagrass coverage and stored belowground carbon for common seagrasses …

Effects Of Elevated Temperature On Gonadal Functions, Cellular Apoptosis, And Oxidative Stress In Atlantic Sea Urchin (Arbacia Punctulata), Jackson B. Johnstone

Theses and Dissertations

Increasing surface sea water temperatures effect on growth, reproduction and development in marine organisms. Sea urchins are excellent indicator species and ideal model organisms to focus on. In this study, I tested the effect of higher temperatures on reproductive functions, heat shock protein (HSP, a chaperone protein produced by cells in response to heat stress) and nitrotyrosine protein (NTP, an indicator of reactive nitrogen species, RNS) expressions, cellular apoptosis, and ceolomic fluid (CF, a body fluid which regulates important physiological processes) conditions in Atlantic sea urchin at three different temperatures. Ten sea urchins were placed in each of six aquariums …

A Snapshot Of The Age, Growth, And Reproductive Status Of Gray Triggerfish (Balistes Capriscus, Gmelin 1789) On Three Artificial Reefs In The Northwest Gulf Of Mexico, Adam M. Lee

Theses and Dissertations

Age, growth, and reproductive status of gray triggerfish (Balistes capriscus) were identified from 2015-2016 on artificial reefs in the northwest Gulf of Mexico. Individuals ranged from 232-432 mm fork length with and a mean fork length of 319 mm. Individuals from age 0.2 to 5.2 yrs were observed with a weight to length relationship of Wg = 1.1 x -104 x FL2.7 (r2 = 0.94, n = 112), where FL = fork length (mm) and Wg = weight (g). A von Bertalanffy growth equation of Lt = 326(1 - e - 0.9 (t + 1.71)) was calculated irrespective …

Effects Of Global Warming On Gonadal Functions, Cellular Apoptosis, And Oxidative Stress In The American Oyster, Sarah B. Nash

Theses and Dissertations

Global warming due to climate change is predicted to intensify the heat stress in marine and coastal organisms, affecting their development, growth and reproductive functions. In this study. I analyzed gonadal development, heat shock protein 70 (HSP70), nitrotyrosine protein (NTP), dinitrophenyl (DNP) expressions, cellular apoptosis, and coelomic fluid (CF) conditions in American oyster. Oysters were placed in six aquariums and exposed to control (24°C), medium (28°C), and high (32°C) temperatures for one week. Higher temperature significantly decreased the number of eggs and sperm. CF protein concentrations also declined compared to control. In contrast, CF pH and HSP70 expression in gonad …

Impacts Of Habitat Attributes And Community Gardens On Urban Bird Communities, Samuel Glenn Ortiz

Theses and Dissertations

The Rio Grande Valley of Southern Texas is a major agricultural region yet has some of the highest hunger rates in the USA. Urbanization and agriculture affect biodiversity, which is well studied, but little is known about how agriculture affects biodiversity in urban areas. We investigated how different urban attributes, including those related to urban farming, impact bird communities in Brownsville and Harlingen, TX, and compared sites that have community gardens to those that do not. To study three key urban habitat characteristics, we identified sites that exhibited all possible combinations of these factors, quantified land cover classes related to …

Measuring Connective Capacity Throughout The Gulf Of Mexico Fishery Management Network, Anthony Rocha Lima

Theses and Dissertations

The Gulf of Mexico provides substantial resources along its 1,680-mile coastline, spanning 5 U.S. states and providing millions of pounds of seafood and hundreds of millions in revenue annually. Continued success of the fishery relies on the ability of a large, complex, multiagency network to find the best solutions to balance the needs of humans, as well as ensure long-term sustainability. Organizations with varying objectives require effective communication when addressing intricate ecosystem-based management topics such as endangered species and regional economies.

To better understand the connectivity within the Gulf fishery management network, an IRB reviewed survey was dispersed to the …

Environmental Conditions In San Martin Lake: Effects Of Eutrophication In An Estuary Associated With The Laguna Madre, Wendy L. Rogers

Theses and Dissertations

San Martin Lake is a shallow water Estuary in the lower Laguna Madre off the Port of Brownsville Shipping channel. It is influenced both by incoming tides and waste water runoff both from local farms and the Brownsville water treatment plants. The resulting mixture of eutrophic water and incoming sea water creates the perfect mix for a potential algal bloom. This study looks at the nutrient levels and environmental conditions in the main basin of the estuary to establish baseline levels and to observe the rate of nutrient clearing being accomplished in this environment. As sport recreation in the area …

Nannochloris Sp. And Oocystis Sp. Algae Exposed To Osmotic Stress For Increased Lipid Production For Use In Biofuels, Laura M. Chavez

Theses and Dissertations

Algal biofuel research is important due to the potential need for replacement of non-renewable fossil fuels and a changing global climate. Under stress, algal cells tend to increase neutral lipid production, which are a suitable source for biofuels. The goal of this study was to subject Nannochloris sp.. and Oocystis sp. algal cells to osmotic stress by modifying sucrose and salinity levels in different treatment medias.

The treatment containing the lowest salinity (15 ppt) and no sucrose yielded the highest lipid fluorescence/cell in Nannochloris sp.. cells (0.00142 ± 0.00044) on day 2 while the treatment containing highest salinity (35ppt) …

Phylogeography Of An Estuarian Calanoid Copepod; Acartia Tonsa In The Texas Gulf Of Mexico, Nicole J. Figueroa

Theses and Dissertations

The calanoid copepod, Acartia tonsa is one of the most abundant and well-studied estuarian species. However, the idea that this cosmopolitan species has unrestricted dispersal and high gene flow has been challenged. In this study, a more holistic picture of the phylogeography of A. tonsa was developed using the mitochondrial gene cytochrome oxidase one (mtCOI). Multiple new lineages were found in the Texas Gulf of Mexico that are basal to Northeastern Atlantic lineages. Connectivity was also observed between Brazil and the Texas Gulf of Mexico. The revised phylogeny shows a clear pattern of cryptic speciation as the species made a …