Earth Sciences Commons^™

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 …

Development Of Lower Rio Grande River Water Quality Transportation Numerical Model For Bi-National River Management, Jose O. Gonzalez

Theses and Dissertations

Traditionally, water quality modelling has focused on modelling individual water bodies. However, water quality management problems must be analyzed at the larger scale to include influences from various water bodies that are interconnected. This paper provides a study on the hydrologic and quality transportation calculation by developing a hydrodynamic (unsteady state) channel routing model using a water-balanced approach. A one dimension Lagrangian river model was developed and applied to the 210 plus miles for the lower Rio Grande River Basin from the Falcon Dam to the head water of Brownsville that pours onto the Gulf of Mexico. This model can …

Thermal Consolidation Of Dredge Sand For Artificial Reef Formations, Alexandro Trevino

Theses and Dissertations

Coral Reef ecosystems have degraded over years due to a variety of environmental issues such as ocean acidification. The continuous stress has detrimental effects on coral reef ecosystems that can possibly lead to the loss of the ecosystem. Our research aims to construct a prototype of an artificial reef by consolidating dredge sand from the ship channels of South Texas. Consolidation is achieved through an aluminum polytetrafluoroethylene self-propagating high temperature process that yields a solid formation to mimic the physical properties of coral reef structures. Using thermodynamic calculations, the variation of initial components was determined that reached an adiabatic temperature …

Investigating The Application Of Multibeam Sonar And Remotely Operated Vehicles In Fish Population Monitoring On Artificial Reefs, Robert Figueroa-Downing

Theses and Dissertations

Implementation of ROVs and multibeam imaging sonar in fisheries research has the potential to improve the accuracy and efficiency of current monitoring practices. This study aimed to 1) compare ROV video and diver abundance estimates; 2) evaluate fish length measurement accuracy from sonar; 3) investigate key differentiating sonar characteristics. Results indicate: 1) Diver surveys captured greater diversity of species; survey methods were comparable with regards to conspicuous species (r = 0.089, p = 0.074); 2) Length measurements from multibeam imaging sonar had high predictive power (Rho = 0.998; p < 0.001) of actual standard lengths and; 3) variations between samples were largely due to swim bladder echo, relative position of the target fish, and schooling characteristics. We conclude that 1) ROVs are less apt at observing cryptic species; 2) The Blueview P900-90 sonar can accurately measure fish length; and 3) swim bladder morphology plays an important role in fish identification.

Creating A Scaling Relationship Between Peak Discharge And Drainage Area To Identify Tile Drainage Inputs Into An Agricultural Stream, Ryan Plath

Theses and Dissertations

Tile drains have been shown to contribute to high levels of nitrate in agricultural streams. Locations of tile drains on a watershed scale, however, are often unknown due to tile drains being located on many separate parcels of private property. This study evaluates the ability of a methodology, using scaling relationships between discharge and drainage area, for locating areas of large tile drainage contribution to Money Creek, in McLean County, Illinois. Additionally, this study examines the difference in scaling relationships and physical stream hydrology between tileflow and no-tileflow conditions. Eight stream sites were created in the watershed, that recorded stage …

Dynamics Of Nitrate, Phosphorus, And Suspended Sediment Transport In Two Agricultural Streams In Central Illinois, Luke W. Lampo

Theses and Dissertations

Nutrients such as nitrate and phosphorus are necessary for life, but excessive amounts can be detrimental. Large amounts of nutrients entering bodies of water can lead to hypoxic zones such as the one in the Gulf of Mexico. Nutrients are also problematic in drinking water reservoirs, as high concentrations of nitrate in drinking water can cause health conditions such as blue baby syndrome and high phosphorus concentrations can lead to algal blooms. Suspended sediment leads to reservoir sedimentation, habitat degradation, and is able to transport particulate nutrients. High nutrient and sediment concentrations are a recurring problem in the drinking water …

Sanitary Sewer Overflows In Columbia, South Carolina And Their Impact On Mercury And Metal Cycling, Alison Emmons

Theses and Dissertations

Objectives. Microbial pathogens and their threat to human health have been the primary concern of sanitary sewer overflows (SSO); however, SSOs may also be a source of metals, including methylmercury, to local waterways. We hypothesized that SSOs had elevated concentrations of metals compared to nearby reference creeks.

Methods. Unfiltered and filtered (0.2 μm) surface water samples were collected monthly between November 2015 and March 2016 from three sewage-impacted creeks in Columbia, South Carolina. During this period, three sewage events were captured including an active SSO, a ruptured force main sewer pipe, and one site downstream from SSOs. In October 2016 …

A Study Of Two Digital Hydrological Networks In South Carolina And An Assessment Of Site Reconnaissance Results From The Sc Department Of Health And Environmental Control Probability Survey For Streams And Rivers, Caitlin Smith

Theses and Dissertations

The South Carolina Department of Health and Environmental Control (SCDHEC), Surface Water Monitoring Section utilizes a probability survey to assess water quality conditions of streams and rivers in the state. The Generalized Random-Tessellation Stratified survey design prioritizes specific stream order (size) subpopulations and spatial distribution in the generation of potential sample sites, and is intended to survey only perennial stream reaches. Site reconnaissance is conducted to assess site suitability and accessibility. The stream characteristics associated with accepted and rejected sites have been recorded since the late 1990s/early 2000s. Data from 2001-2016 was analyzed to assess apparent trends in both rejected …

A Comparison Of Pesticide Monitoring Programs, State Vs. Federal, Justin Marshall

Theses and Dissertations

Exposure to pesticide residues continues to be a threat to both human and environmental health despite increased efforts in the agricultural industry to control end-product levels. Multiple government agencies routinely sample and screen common agricultural commodities (fruits and vegetables) for pesticide residues, albeit to do so they use different commodity sampling methods and satisfy different program objectives. Often, results of such screening programs are used in a supplementary fashion in human and environmental health studies, but rarely are the results studied against one another. Six years of archived data (narrowed down from 14) of two separate pesticide monitoring programs were …

Short-Term Effects Of Nutrients On A Barrier Island Grassland Community, Ashley Moulton

Theses and Dissertations

Increased nutrient availability globally has the potential to affect community functional composition of plants in nutrient limited environments, such as coastal grassland systems. Stability of these systems are threatened worldwide by urbanization, as well as effects of sea level rise and increased frequency and intensity of storms, and atmospheric N deposition, associated with climate change. Annual net primary productivity (ANPP), species composition, and functional traits (community weighted specific leaf area (CWSLA), leaf area index (LAI), growth form and photosynthetic pathway) were measured across four treatments to assess multiple resource limitation of nitrogen (N) and phosphorus (P) and functional community response …