Physical Sciences and Mathematics Commons^™

Stream Microbial Communities As Potential Indicators Of River And Landscape Disturbance In North-Central Arkansas, Wilson Howard Johnson

Graduate Theses and Dissertations

In the past decade, 29 shale basins have been actively developed across 20 states for extraction of natural gas (NG) via horizontal drilling/hydraulic fracturing (=fracking). This includes ~5000 wells within the Fayetteville shale of north-central Arkansas. Development often impacts both river- and landscapes, and management requires catchment-level evaluations over time, with organismal presence/absence as indicators. For this study next-generation sequencing was used to identify/characterize microbial communities within biofilm of eight Arkansas River tributaries, so as to gauge potential catchment influences. Streams spanned a gradient of landscape features and hydrological flows, with four serving as ‘potentially impacted catchment zones’ (PICZ) and …

Dietary Effects On The Stoichiometry Of Growth, Regulation, And Wastes Of Ozark Stream Insect Detritivores, Halvor Matthew Halvorson

Graduate Theses and Dissertations

A widespread stressor, anthropogenic nitrogen (N) and phosphorus (P) pollution can increase resource nutrient content and alter animal community composition in freshwater ecosystems. In this dissertation, I used ecological stoichiometry theory to examine effects of diet nutrient content and leaf litter type on growth, regulation, and wastes of aquatic invertebrate detritivores. I tested effects of leaf litter diet carbon:phosphorus (C:P) on growth and stoichiometric regulation of the detritivorous caddisfly Pycnopsyche lepida and used results to determine a threshold elemental ratio of oak litter C:P=1620 that confers peak growth of this species. This empirical, growth-based approach provided a more accurate estimate …

The Role Of Hydrologic Regimes In Driving Morphologic Divergence And The Trait Compositions Of Fish Assemblages, Lindsey A. Bruckerhoff

Graduate Theses and Dissertations

The hydrologic regime is an important determinant of the ecological integrity of a stream. Hydrologic regimes are defined by the magnitude, timing, frequency, rate of change, and duration of high and low flow events and capture long term patterns of variability and predictability of water movement in a stream. Flow regimes influence many aspects of the biophysical environment in lotic systems; therefore organisms have adapted to natural flow patterns. We investigated how fish have adapted to flow regimes at both a population and community level. In the first study presented in this thesis, we hypothesized fish exhibit phenotypic divergence to …

Economic Feasibility Of Aquaponics In Arkansas, Leah Ashley English

Graduate Theses and Dissertations

Concerns regarding population growth and resource scarcity have led to a recent renaissance of food production research. Over the past few decades, scientists have discovered new and innovative methods for growing food that, cumulatively, may hold the key to efficiently and sustainably feeding an ever-increasing world population. One method, known as aquaponics, has shown promise as being a sustainable solution for producing food locally in all parts of the world. Although many studies have shown aquaponic food production to be technically feasible, there are relatively few studies concerning the economic feasibility of aquaponics in various regions. To determine whether aquaponics …

Hydrology-Biology Response Relationships In The Ozark Highlands, Dustin Thomas Lynch

Graduate Theses and Dissertations

I examined flow-ecology relationships among stream communities in the Ozark Highlands, USA. I sampled fish, crayfish, and benthic macroinvertebrates during two consecutive summers, including a drought year (2012) and a flood year (2013). Biological response variables related to community structure were assessed via two different statistical methods: an Information Theoretic approach relating response variables to a priori selected predictor variables incorporating hydrology, habitat, geomorphology, and water quality, and canonical ordination using forward selection to relate these same response variables to a large assortment of hydrologic metrics. In addition to assessing metrics related to predicted natural flow, flow alteration at gaged …

Reducing Nutrient Runoff From Poultry Production Facilities Using Locally-Sourced Iron And Aluminum Byproducts, Sheri Lynn Herron

Graduate Theses and Dissertations

Phosphorus (P) inputs to fresh waters can accelerate the eutrophication process. Agricultural nutrient runoff has been shown to be a contributor of P and nitrogen (N). Broiler production areas were evaluated for their potential to contribute P and N to runoff. Broiler house dust (BHD) samples were analyzed and compared to broiler litter (BL), rainfall simulations were conducted on plots adjacent to broiler house fans to evaluate nutrient enrichment in runoff from deposited dust, and runoff was automatically sampled at two culverts draining the land around broiler houses. Following this, an on-farm byproduct containment and nutrient removal structure was designed …

Oxidative Stress In Algae: Method Development And Effects Of Temperature On Antioxidant Nuclear Signaling Compounds, Md Noman Siddiqui

Open Access Theses

Non-enzymatic antioxidants neutralize the oxidative stress through scavenging reactive oxygen species. The structural complexity of non-enzymatic nuclear signaling antioxidants poses are more challenges for traditional quantitative analysis as these compounds have multiple forms and structurally diverse than proteins and therefore, challenge traditional analytical techniques. Current analytical methods cannot distinguish the carotenoids, and vitamin A and D metabolites within a single sample. To find an appropriate method to measure all the nuclear signaling compounds in algae, Isochrysis sp. , under thermal stress, HPLC/ESI-MS and HPLC /APPI-MS was used. Standards of those compounds were run by QQQ HPLC/ ESI-MS and HPLC /APPI-MS …

Assessing Trichloromethane Formation And Control In Algal-Stimulated Waters Amended With Nitrogen And Phosphorus, Clinton Mash

Graduate Theses and Dissertations

Nitrogen (N) and phosphorus (P) enrichments can stimulate algal growth in drinking water sources, which can cause increased production of disinfection byproduct (DBP) precursors. However, the effect of systematic N and P enrichments on DBP formation and control has not been adequately studied. In this work, we enriched samples from a drinking water source - sampled on April 5, May 30, and August 19, 2013 - with N and P to stimulate algal growth at N:P ratios covering almost five orders of magnitude (0.2-4,429). To simulate DBP-precursor removal processes at drinking water treatment plants (DWTPs), the samples were treated with …

Reservoir Management Techniques To Enhance Biological Productivity And Protect Water Quality, Ben Alan Thompson

Graduate Theses and Dissertations

Three reservoirs of similar size, watershed land use, and qualitative characteristics in northwest Arkansas, USA were selected to compare the effects of chemical fertilization and pulsed artificial-upwelling on whole-lake productivity, specifically primary production and phytoplankton biomass. Numerous water quality parameters were quantified over a two year period (2011-13) with the goal of understanding how each management technique would stimulate productivity. This experiment was the first step towards a larger goal to ultimately enhance sport fish production. The first year of monitoring occurred in 2011 and served as a control year for the three lakes. Treatments were initiated in two of …

A Cradle To Farm Gate Life Cycle Analysis Of Water Use In U.S. Pork Production, Eric Boles

Graduate Theses and Dissertations

The intent of this study was to analyze water use across a range of regions, scales and practices of the U.S. pork industry. A Life Cycle Assessment of water use within the pork supply chain was performed. Cumulative water use was the environmental impact category used in the LCA to evaluate the impacts of pork production processes throughout the pork supply chain. The functional unit for the analysis was the volume of water required to produce one kilogram of swine (live weight) at the farm gate.

A comprehensive literature review was used to design and propagate algorithms for the National …

Air-Water Gas Exchange And The Carbon Cycle Of Green Bay, Lake Michigan, James Waples

Theses and Dissertations

The purpose of this study was to constrain estimates of the kinetics of gas transfer across the air-water interface as well as quantify the net flux of carbon between southern Green Bay (1635 km²) and the atmosphere.

In 1994 and 1995, over 3500 measurements of surface water CH₄ and CO₂ were made using a continuous sample disk equilibrator. Estimates of CH₄ flux from southern Green Bay to the atmosphere based on air-water concentration gradients, shear corrected wind speeds and the U/K (wind speed/transfer coefficient) relationship of Broecker et al. (1978) agreed to within ~10% of …