Browsing by Subject "Conservation"
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Item A shipping crate from the 1865 California shipwreck Brother Jonathan: hardware from the Russell and Erwin Manufacturing Company(Texas A&M University, 2006-08-16) Sowden, Carrie ElizabethIn the summer of 2000, divers recovered a large shipping crate from the wreck of the Brother Jonathan, a steamboat that sank off of Crescent City, California on 30 July 1865. Ownership of the crate was taken over by the state of California and was sent to Texas A&M??s Conservation Research Laboratory for excavation and conservation. As soon as work began, it became clear that the crate contained a shipment of a variety of hardware most likely destined for a general store as each of the artifacts discovered was found in high quantities. Also, there was a wide variety of artifacts discovered, tools, architectural pieces, food preparation, fur trapping, and personal items. The crate was shipped from San Francisco from the warehouse of the Russell and Erwin Manufacturing Company; however, its final destination is unknown. Records for this warehouse and for the boat were destroyed in the earthquake and fire of 1906, so the destination for these goods is purely speculative. Using information from the excavation of the crate and a historical analysis of the contents led to a plausible theory. After careful review, it seems most likely that the crate was intended for a general store in a small town with a rural customer base.Item Achieving the minimum 20 percent conservation and reuse mandate in the SWIFT process in Texas(2015-05) Harris, Shannon Carrie; Steiner, Frederick R.; Lieberknecht, Katherine E.; Huber, Karen L.In November 2013, the citizens of Texas approved a new water infrastructure-financing plan called the State Water Implementation Fund for Texas (SWIFT). SWIFT funds will provide low-cost loans for water projects included in the State Water Plan. A few conditions catalyzed this historic legislation, including a year of exceptionally severe drought in 2011, and the 2012 State Water Plan, the first such plan released since 2007. This document assumes one scenario for water planning in Texas in which the population nearly doubles and historic dry periods persist, resulting in an 8.3 million acre feet water shortage. A minimum of 20 percent of the fund must finance conservation and reuse water supply and enhancement methods. These projects must have associated capital costs and be included in the State Water Plan. Conservation strategies often have no capital costs, or if they do, expenses are lower than for other techniques such as desalination. Therefore, this research seeks to discover whether it is possible to meet the 20 percent minimum set-aside. The study focuses mostly on conservation procedures since reuse typically incurs significantly higher costs, and could, theoretically, meet the set-aside alone. Texas water users must think strategically about conservation in order meet the minimum set-aside. In a state with a history of large infrastructure projects, such as 60 years of reservoir construction, planners are no longer in tune with a diverse array of potential projects. Alternative water enhancement techniques not only supply water, but provide benefits to the local ecology and economy. The research also explores alternative water conservation technologies. Texans are fiercely independent, pragmatic, innovative people by nature. The cultural history of the state underscores these facts. The SWIFT fund is a result of creative thinking by planners, legislators, and citizens to alleviate problems before they become serious. That same vision is necessary to inspire synergies between participants using auxiliary water technologies financed through new funding mechanisms resulted from changing economic philosophies. The citizens of the state, and its ecological health, will benefit if they can muster the political will to resourcefully meet the minimum 20 percent conservation and reuse set-aside.Item An analysis of forest change : a case study of the Chocó-Andean conservation corridor in the Upper Guayllabamba Watershed, Ecuador(2010-05) Gordon, Jessica Danielle; Young, Kenneth R.; Richardson, Richard H.Deforestation in the tropics is considered to be a primary cause for worldwide loss of biological diversity. Future land use decisions have the potential to escalate or ameliorate this global problem. The goal of this research is to present a case study of an analysis of forest change within the Chocó-Andean Conservation Corridor in the Upper Guayllabamba Watershed in Northwestern Ecuador. Fieldwork, remote sensing, and a Geographic Information System (GIS) were used to analyze land use/land cover changes within the corridor. Change detection from 1986 to 2001 using Landsat imagery confirmed that forests were rapidly being converted to other land covers, but patterns of deforestation rates varied dramatically for different types of forests. The average annual rate of overall loss of forest was 2.7% for lower montane forest, 1.7% for mid-slope cloud forest 2.1% for upper montane forest, and 2.0% for riparian forests. The patterns of deforestation also varied based on scales of analysis. For example, the overall loss of forest within the southern portion of the Chocó-Andean Conservation Corridor occurred at an average rate of 1.3% per year, while the overall annual rate of forest loss within particular sub-watersheds varied from 0.2%-3.1% and the annual average rate of overall forest loss surrounding particular communities ranged from 0.3%-3.3%. Fifty interviews were conducted in 2003 in seven communities within the conservation corridor to determine local perspectives of current land use practices, past land use trends, and future land use goals; regional changes in the forest; and opinions of local conservation projects. An intriguing finding of the study is that remote sensing in isolation of fieldwork would have provided incomplete or misleading results. For example, the community that had the most deforestation between 1986 and 2001 was the community where the conservation projects were actually the most successful, based upon local resident opinion. This report asserts that a holistic approach to conservation is needed to reconcile environmental and socio-cultural needs in order to maintain and improve forest habitat and hydrologic connectivity at multiple spatial scales (including community-level, watershed, and regional) by extending conservation efforts beyond protected areas and utilizing a basin-scale perspective to make land use decisions that maintain biodiversity and promote watershed protection.Item Biogeography of upland bird communities in the Peruvian Amazon(2009-12) Pomara, Lazarus Yates; Young, Kenneth R.; Barth, Robert H.; Dull, Robert A.; Miller, Jennifer A.; Ruokolainen, KalleThe western Amazon is known to be one of the most biologically diverse regions in the world, yet information about the spatial distribution of that biodiversity and the processes governing its distribution remains scarce. An improved understanding of those biogeographic patterns and processes can inform conservation and development planning in areas where anthropogenic landscape change is ongoing. Spatial components of biodiversity are known to be influenced by historical and present-day physical and human geographic processes. There is evidence that major Amazonian rivers form the boundaries of biological regions, at least for birds. Other factors that may influence bird species composition include the dispersal limitations of individual species, forest plant species composition and structure, topography, forest fragmentation, and hunting. Sites where bird species composition was measured in this study represented mature, upland forest on both sides of the Amazon River, and a range of non-flooded forest types, as indicated by soil and plant surveys. Bird species compositional variation was closely correlated with variation in plant species composition, human disturbance associated with forest fragmentation, and position north or south of the Amazon River. The strongest differences were between opposite sides of the river, even though local environments, including plant composition, were not different on the two sides. This strongly suggests that historical biogeographic factors, rather than present-day environmental gradients, are responsible for bioregional boundaries at Amazonian rivers. The difference between plant and bird distributions at this scale underscores the pressing need to re-evaluate general notions of bioregional complexity and pattern in the Amazon basin. Locally, the influence of habitat fragmentation on animal communities, including reduced species richness, was confirmed. The influence of local floristic variation is of particular importance due to its ubiquity across western Amazonia. Thus, understanding the distributions of soils and vegetation is critical for explaining Amazonian animal diversity. The use of these factors to model bird community heterogeneity contradicts assumptions that the processes shaping Amazonian animal community diversity are too complex to measure efficiently, and their use contributes a new understanding of the dimensions of that diversity.Item Biological growth on the Alamo(2009-05) Gallagher, Casey Amber; Gale, Frances R.The limestone façade of the Alamo shows several areas of biological growth with black and gray streaks and blotches discoloring the stone. This thesis investigates the identity of the microorganisms on the stone, using two: DNA identification, and lab cultures grown from samples of the biofilm. By using both approaches, a better understanding was gained of the range of organisms present. Through these tests, it was found that the dominant organism on the limestone is cyanobacteria, of the genus Chrooccocus. Lab cultures revealed other organisms, including possibly fungi photobionts and algae. Through analysis and comparison of historic and contemporary photographs, patterns of recolonization are investigated. To further understand the effects of the biocide treatments, cultured samples were treated, and their reactions monitored. To better understand the possible relationship between the Alamo stone and its colonizing organisms, physical properties of the stone were investigated. SEM images, Edax minerology and water absorption were used to characterize the stone. This study is the first of its kind to investigate Native Texas quarried architectural limestone. Although studies have been conducted on historic monuments around the world to identify biological growth, none have focused on Texas limestone. By using both DNA and lab culture identification, this study adds to a wealth of investigations of other conservation professionals, applying it to a subject that has not been studied in this way before. By understanding the colonizing organisms, a sustainable conservation regimen can be determined.Item “Clean water and better bass fishing" : bass anglers and bass culture, 1968-1980(2013-08) Sheu, Sherri Angel; Engelhardt, Elizabeth S. D. (Elizabeth Sanders Delwiche), 1969-This report argues that bass anglers constituted an important facet of the American environmental movement during the 1970s, especially though the Bass Anglers Sportsman Society (B.A.S.S.), founded by Alabama native Ray Scott in 1968. During this time period, bass anglers formulated a distinct strain of environmentalism rooted in the technologically-mediated landscape where bass anglers caught bass. This form of environmentalism carved out a social space wherein bass anglers could maintain preexisting social orders and hierarchies while addressing issues of the broader environmental movement, including industrial water pollution, poaching, and air quality. As such, bass anglers demonstrate the continual involvement of sportsmen within the environmental movement and the political diversity of the environmental movement.Item Conservation engineering and agricultural terracing in Tlaxcala, Mexico(2014-05) LaFevor, Matthew Cole; Doolittle, William EmeryThis research examines the practice of hillslope terracing in the state of Tlaxcala, Mexico. It explores how one popular terrace form, zanja-bordo (ditch-and-border) terraces, is employed in two distinct, though sometimes related contexts: (1) producing crops (agriculture) and (2) protecting natural resources (conservation). It first traces the use of zanja-bordo terraces in traditional agriculture in the region, highlighting some of the major elements of their form and function, issues surrounding their antiquity, and their possible role in the landscape degradation so prevalent in the region today. Moving from this agricultural context, the dissertation next examines the role of zanja-bordo terraces in landscape restoration efforts in Tlaxcala. It demonstrates the key role that active and prolonged maintenance plays in long-term efforts to restore previously degraded farmland back to productive capacity. The dissertation then examines more broadly how government programs to promote zanja-bordo terracing in the region impact farmers, whose ancestors have been building zanja-bordo terraces for centuries. Findings from the collection, synthesis, analysis, and groundtruthing of written data on governmental terracing projects in the state reveal that while perhaps well intentioned, these programs did little to promote sustainable agricultural development or environmental conservation in the region. Finally, the dissertation moves above the 3,000-meter mark to examine the relatively recent phenomenon of high-elevation terracing in Mexico's national parks. Conceived as a means of erosion mitigation, water conservation, reforestation, and even fire suppression, government agencies now construct zanja-bordo terraces throughout the understory of many of Mexico's subalpine forests. A case study of the la Malinche (Malintzi or Matlalcueyatl) National Protected Area illustrates some of the difficulties in examining each of the claimed benefits of terracing in these environments. Whether for agriculture or restoration, as a techno-developmental strategy, or as a tool for soil and water conservation, zanja-bordo terraces are shown to be an adaptable and effective hillslope management technology. This dissertation demonstrates, however, that successful adaptation and implementation of zanja-bordo technologies into different contexts largely depends on the effective planning, monitoring, and maintenance of terrace structures and processes. Ultimately, the sustainability of zanja-bordo terracing relates more to issues of contextualization and human motivation than to questions of technological innovation.Item Conservation of vertebrate biodiversity in Texas: Setting priorities for reserve selection(2006-12) Law, Jeffrey J.; Willig, Michael R.; McIntyre, Nancy E.; Cox, Stephen B.Species extinction rates are increasing throughout the world. A way to combat the global loss of species is through the creation of well-placed wildlife reserves. The principle objective of this study was to determine which areas throughout Texas most efficiently and effectively preserve extant vertebrate biodiversity (amphibians, reptiles, and mammals) if protected in reserves. Secondarily, I quantified the effectiveness of using a particular vertebrate class as a surrogate for others. The Sites Simulated Annealing Algorithm was used to determine areas that effectively preserve biodiversity while minimizing cost. This was accomplished through the use of irreplaceability values. Irreplaceability is equal to the number of times each planning unit is selected in a final solution to the SSAA. The SSAA was run 200 times for each scenario to determine this value. Species distribution maps obtained from the Texas GAP project were the basis for biodiversity data, whereas economic value of land came from the National Agriculture Statistics Service. I identified the best sites to establish reserves with current protected areas forced into the solution and also ignoring current protection status. The areas of the highest conservation concern, based on irreplaceability, were the Edwards Plateau of Central Texas and the Trans Pecos Region of West Texas. Although the irreplaceability values of planning units for incorporation into the reserve systems are correlated for all possible pairs of vertebrate classes, the associations are quite weak.Item Estimating site occupancy for four threatened mammals in southeastern Laos(2014-08) Tilker, Andrew; Keitt, Timothy H.The tropical forests of Indochina harbor a suite of globally threatened tropical mammal species. These species are difficult to detect, and subsequently understudied. Noninvasive camera trapping was used to survey terrestrial mammals from a protected area in southeastern Lao PDR (Xe Sap National Protected Area). The presence-absence of four mammals (mainland serow Capricornis milneedwardsii, muntjac Muntiacus spp., macaque Macaca spp., and wild pig Sus scrofa) was modeled in an occupancy framework thereby accounting for detection probabilities. Our goals were to establish baseline occupancy data to assist with biological monitoring and to better understand the factors influencing the distribution of the target species. Naïve occupancy, or the proportion of sites at which the target species was detected, was 0.58 for muntjac, 0.55 for macaque, 0.38 for wild pig, and 0.30 for serow. True occupancy estimates (Ψ ± SE) from top-ranked models was 0.79 ± 0.21 for macaque, 0.74 ± 0.13 for muntjac, 0.51 ± 0.13 for wild pig, and 0.48 ± 0.18 for serow. The results underscore the importance of accounting for imperfect detection rates when studying rare or elusive species. I included two site covariates (forest type and distance to nearest village) in the occupancy models. Estimating occupancy as a function of site covariates improved model performance and provided insight into landscape-level factors that affect species occurrence. In the top-ranked models, serow occupancy was higher in hill evergreen forest (HEGF) than semi-evergreen forest (SEGF). Muntjac occupancy was higher in areas further from villages. Macaque occupancy was higher in areas closer to villages. Wild pig occupancy was higher in areas further from villages and in HEGF. I recommend using an occupancy framework to analyze occurrence data for difficult-to-study tropical mammal species. The results highlight the importance of Xe Sap NPA for large mammal conservation in the region.Item Evaluating sustainability : energy and water conservation at UT(2015-08) Garcia, Oscar III; Eaton, David J.; Kreitler, Charles; Ontiveros, Juan MThe University of Texas at Austin (UT) has invested in improving sustainability on campus through its administration and operations, but it has yet to measure its performance through a comprehensive methodology. This study compares the sustainability practices at two peer universities with UT, and displays the patterns of energy and water consumption in buildings. This report illustrates energy and water conservation through indexed GIS maps.Item Forest diversity and conservation in the western Amazon based on tree inventory and remote sensing data(2011-12) Wang, Yung-ho Ophelia; Young, Kenneth R.; Crews, Kelley A.; Miller, Jennifer A.; Sarkar, Sahotra; Pitman, Nigel C.This dissertation contributes to debates in conservation biogeography by examining the spatial heterogeneity of local and regional tree diversity feature using ground and remotely sensed data, and by taking approaches to design a spatially explicit landscape zonation map for future conservation planning in western Amazon, one of the most biodiverse regions on Earth. Fine scale tree diversity and conservation-related studies took place in tropical rainforests in southeastern Ecuador, whereas coarse scale tree diversity research was conducted using data from eastern Ecuador and northern Peru. The lack of species assemblages within three 1-ha tree inventory plots in southeastern Ecuador and the weak correlations with biophysical environment implied that neutral processes may contribute to species diversity. In contrast, differences in species assemblages between plots corresponded to relative geographic locations of the plots, indicating that geographic distance or dispersal limitation may play an important role influencing diversity patterns at a regional scale. Species of high local abundance was found in 1-ha tree inventory plots in western Amazon. Changes in density of locally abundant species between western and eastern plots indicated that some species may have limited distributions. Shifts in species dominance and the significant relationship between floristic variation and geographic distances between plots implied dispersal limitation. Variation in rainfall showed significant relationship with species composition. Therefore, dispersal limitation and precipitation seasonality are potentially the most significant factors that contribute to spatial differences in tree diversity in western Amazon. Characteristics of canopy shadows and palm stem density based on fine-resolution aerial photographs were characterized as exploratory analyses to extract alpha and beta diversity features using remotely sensed data. A zonation map design using multispectral habitat classification and other remote sensing data performed well in its spatial arrangement when potential indigenous land use was integrated. Based on the results of analyses for conservation biogeography, this dissertation concludes that local and regional tree diversity may be influenced by dispersal limitation and seasonality, and that the application of remote sensing for biodiversity conservation is feasible in very species-rich forests.Item Genomic signatures of host-associated differentation in phytophagous insects(2015-12) Bennett, Nichole Lynn; Parmesan, Camille, 1961-; Singer, Michael CAlthough there have been many studies investigating host-associated genomic differentiation in phytophagous insects feeding on different host plants, this review serves to compile the current state of knowledge of the conditions for host-associated genomic differentiation and the patterns and processes of genome-wide divergence. While there are a multitude of theories and expectations for when host-associated genomic differentiation will occur and how, more empirical work is needed on how this operates in natural herbivorous insect systems. In the future, this knowledge of how host-associated genomic differentiation operates may be used to better control better agricultural pests, to manage invasive species, and to develop conservation strategies.Item Hair today, gone tomorrow: the degradation and conservation of archaeological hair fibers(2009-05-15) Sager, Rebecca M.The research of this work describes the degradation and conservation of archaeological hair fibers. Chapter I will be a brief overview, with Chapter II following with a literary review and definition of terms. Chapter III focuses on research centered on the structure of hair fibers and their physical and chemical attributes. It will also focus on the archaeological and historical evidence of hair fiber use by humans. This research will help form the backbone of the paper and experiments performed. The next chapter focuses on the degradation of hair fibers in different environments. Hair fibers left in underwater, open air, burial, and arid environments are monitored for degree of degradation and brittleness. The hair fiber types used are four commonly found hair fibers types: coarse wool, fine wool, mohair, and human hair. After deposition, conservation using silicone oil treatment is tested on the degraded hair fibers. When silicone oil treatment proves to be a viable conservation method, the technique is then be applied to two artifacts. The two artifacts used are a Victorian era watch fob made from human hair and hair fibers mixed with tar from the excavation of Kittern in Bulgaria. Chapter VII deals with the conclusions of the experiments as a whole. The degradation of the fibers in different environmental conditions show that burial in acidic sandy clay is the most detrimental to hair fibers, while hair fibers from arid, dry environments are brittle, but well preserved aesthetically. The silicone oil treatments are shown to be viable treatment methods with positive results for all of the fibers tested, including two artifacts, a Victorian watch fob made from human hair fibers and hair fibers mixed with a tar-like substance from the shipwreck Kittern in Bulgaria.Item Highest & best use : strategies for growth management and agriculture and prairie conservation in the SH130 corridor(2008-05) Abee-Taulli, Pamela Jo, 1960-; Butler, Kent S.The population of central Texas is increasing rapidly, and urbanization and suburban development continue amid projections of unprecedented growth to come. How is this affecting the expanses of rich agricultural land and remaining scraps of Blackland Prairie upon which the agricultural industry of east central Texas was built? State Highway 130 is partially complete – providing an urban-area bypass intended to alleviate traffic on I35 between San Marcos and Georgetown. In view of the building of this new transit and development corridor to the east of I35, on the eastern edge of Austin, what can be done to preserve agriculture and native prairie on Austin’s urban fringe? In this PR, I examine this question in terms of two essential components: growth management and land conservation. There are numerous studies on the structures and efficacies of growth management tools and of land conservation strategies, but there is little discussion of the role of growth management in relation specifically to urban and urban-fringe agriculture. I begin with a literature review, surveying the current state of study and practice with regard to growth management and open space & agricultural land conservation. This is followed by a case study of state-level open space conservation policy in Georgia, from which I draw lessons relevant to my case. The next step is to frame the potential management and conservation policies presented win the literature review and case study within the context of local practices, thus narrowing the focus of analysis to the confines of my study area: an approximately 20-mile wide, 58-mile long corridor along a portion of SH130. To gauge the possibilities for management and conservation within the study area, I have produced a matrix of jurisdictions and policy options, and an inventory of vacant land. Using the matrix I analyze, on the one hand, the relevant legal codes available to each jurisdiction, and on the other hand, local attitudes toward growth and agriculture. The land inventory is a graphic presentation – through GIS mapping – of factors critical to the potential preservation of open space. The final operation is to sketch a larger proposal within which this study would fit as a preliminary step. Here I suggest an implementation plan, based on the Envision Central Texas model, and recommend directions for future research.Item The horny toad man : a battle against time and looming public apathy to save Texas’ most iconic reptile(2014-12) Dropkin, Alexander Joseph; Todd, RussellBill Brooks is worried about the future of his organization, perhaps even more than he is about the future of horned lizards. Brooks is the president and a founding member of the Horned Lizard Conservation Society, a nonprofit with the goal of protecting all species of horned lizard. The HLCS was founded in Austin in 1991, after its members realized that populations of Texas horned lizards, Phrynosoma cornutum, had crashed at some point in the preceding decades; they wanted to both figure out what had happened to the lizards and how to bring them back. Cornutum is an iconic species and the state reptile, and almost all Texans over the age of 40 can remember seeing them in the hundreds as children. Flash-forward a quarter of a century, and a lot of these founding members are either old and grey or deceased. HLCS membership is down, and Brooks thinks that if there aren’t any of his kind left (Texans that grew up with “horny toads”), there’ll be no one left to care. Herpetologists are working on returning healthy horned lizard populations to the wild, and both reintroduction and relocation programs are showing signs of success. But can they work, and will it be too late for Brooks’ organization and a Texas identity dependent upon horned lizards?Item Human dimensions of conservation, land use, and climate change in Huascaran National Park, Peru(2008-08) Lipton, Jennifer Kristen; Young, Kenneth R.This research adopts a multi-scale approach to examine the patterns, processes, and perceptions of landscape change within the core and buffer zone of Huascaran National Park, Peru. Within the park’s boundaries are the extensively glaciated Cordillera Blanca Mountains, where runoff from glaciers feeds into lakes, streams, and wetlands to provide hydrologic resources to populations on the periphery for agriculture, as well as hydropower to populations in distant urban areas. Inhabitants living on the periphery have livelihoods that are dependant upon land and natural resources found within the park’s core and buffer zone, while governance institutions mediate access and resource use. Landscape transformations occurring within and around the park are a result of human agency, biophysical change, and global climate change. A suite of qualitative and quantitative methodologies were used to investigate the coupled social and ecological dynamics of conservation, land use, and implications of climate change in Huascaran National Park. The principal objectives of this research were to assess the spatial and temporal patterns of landscape change using land-use and land-cover data from remotely sensed imagery and to examine the role of institutions on resource governance at multiple scales. A hybrid classification method was used to classify Landsat (TM and ETM+) satellite data for the years of 1987 and 2001. Hypotheses regarding the spatial and temporal dynamics of land-cover change were tested. Results indicate that the percent of land cover from the woodland, cropland, and snow and ice classes were reduced internal to the core of the national park, while the land-cover class of shrubland increased. Interviews with 143 informants revealed perceptions of landscape change and narratives of socio-political land use change. Interview data corroborated the findings of reduced land cover in the snow and ice class. Data also demonstrated that legacies of land tenure and governance are essential for evaluating the adaptive capacity of different institutions and communities confronting conditions of climate change. This research contributes to literature on dynamics and processes of landscape change by bridging analytical frameworks from landscape ecology, cultural and political ecology, and land change science and contributing to human dimensions of global change research.Item Identifying entrenchment issues in a protected areas dispute : a case study of the Białowieża Forest conflict in Poland(2011-12) Sekowski, Agnes Janina; Campbell, Craig A. R., 1973-; Wong, Patrick; Bychkova-Jordan, BellaThe Białowieża Forest (or Belovezhskaya Pushcha in Belarusian) is considered the last primeval forest in lowland Europe, straddling the border of Poland and Belarus in a 41/59 percent split. This project investigates the various issues involved in the most recent negotiations process that attempted to incorporate non-park areas of the Białowieża Forest in Poland into the Białowieża National Park. It seeks to understand the entrenchment of stakeholders on opposing sides of this protected areas dispute that has been underway since the area was first designated a Nature Reserve in 1921. An interview-based case study approach was used to explore prevalent themes and emerging narratives of the conflict, such as stakeholder relationships, competing conservation ideologies, economic factors, social tensions, administrative issues, and media portrayal.Item An inconvenient thirst : a look at the 2008-2009 Texas drought(2009-12) Cheng, Christina, 1981-; Burd, Gene; Perez, DominoThe 2008-2009 Texas drought rivals the 1950s drought, known as the “drought of record,” as one of the state’s worst droughts in recent memory. Prolonged periods of little to no precipitation combined with high temperatures and the strain of population growth have created disastrous conditions especially across the southern and central regions of the state, which have been hardest and longest. At one point, more than 83 percent of the entire state was in some form of drought and the United States Department of Agriculture declared more than half the state as a primary natural disaster area due to losses from drought, above-normal temperatures and associated wildfires. More than $4 billion in agricultural losses have been predicted as a result of the drought. Even after heavy rains have lifted nearly all of Texas out of drought, there are still counties in extreme and exceptional drought. It is clear that water issues will continue to impact the state socially, economically and ecologically, so it is crucial for all Texans to have a better understanding of the myriad ramifications drought can have on various industries and communities throughout the state.Item Invasion risk and impacts of a popular aquarium trade fish and the implications for policy and conservation management(2014-05) Dugan, Laura Elizabeth; Hendrickson, Dean; Parmesan, Camille, 1961-Invasive species, a top threat affecting global biodiversity, become invasive through a process including four stages: transport, establishment, spread, impact and integration. Species currently in this process provide opportunities to empirically derive the mechanisms driving each of these stages, make predictions based on these mechanisms and then to test these predictions. This research examines the current invaded distribution, potential invasion and community-level impacts of a popular aquarium trade fish (Hemichromis guttatus Günther, 1862) in an endemic hotspot, Cuatro Ciénegas, in Coahuila, México and discusses the policy and conservation management implications of these findings. In Chapter 1, the problem of invasive species, the study site and the focal species of this work are introduced. In Chapter 2, the critical thermal minimum and maximum temperature limits and temperature preference of H. guttatus are identified because temperature is hypothesized to be an important factor controlling this fish’s distribution. The results indicate that H. guttatus has a wide temperature tolerance range (a characteristic of a ‘good’ invader), that preference is a more informative metric for predicting invasion than absolute tolerances, and that resource-poor environments may promote searching behaviors that cause an invasive fish to increase its range. In Chapter 3, the results of a field survey are analyzed and temperature, pH, depth and the presence of vegetation are all found to be related to H. guttatus presence. Invasion risk of several as-of-yet uninvaded sites in Cuatro Ciénegas is assessed. In Chapter 4, competitive and predatory interactions of H. guttatus on an endemic, threatened cichlid (Herichthys minckleyi) and a macroinvertebrate community respectively are investigated. The results suggest that while H. guttatus does not directly impact H. minckleyi through competition in these conditions, it may inhibit reproduction and alter H. minckleyi’s behavior through aggressive interactions. In Chapter 5, all results are synthesized and a determination of the invasive status of H. guttatus in Cuatro Ciénegas is made. The results presented here will be useful in identifying areas with a high risk of invasion by this popular ornamental fish, thus allowing the implementation of policy and management actions to prevent or at least ameliorate the impacts of an invasion and will add to the growing knowledge of how invasive species affect native systems.
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