Digital Commons Network^™

Divergent Responses Of Cryptic Invasive Watermilfoil To Treatment With Auxinic Herbicides In A Large Michigan Lake, Syndell R. Parks

Masters Theses

Invasive plants are a major concern for environmental managers. Cryptic invasive taxa present additional challenges because of their potential to respond differently to management efforts. Invasive Eurasian watermilfoil (Myriophyllum spicatum) and hybrid watermilfoil (Myriophyllum spicatum x Myriophyllum sibiricum) cannot be reliably distinguished based on morphological characters and are therefore cryptic taxa. Laboratory studies show that on average, hybrid watermilfoil grows faster, branches more, and is less responsive to standard control measures developed for Eurasian watermilfoil. These laboratory results predict less effective control of hybrid watermilfoil in mixed populations treated uniformly with one of these control measures. However, to date there …

A New Adaptive Landscape: Urbanization As A Strong Evolutionary Force, Lauren Christie Breza

Masters Theses

Urbanization is rapidly increasing as human population growth steadily grows, but there is little consensus of the ecological consequence of this population shift and almost no information of the evolutionary consequences for local biodiversity. Nearly two-thirds of the world’s population will live in city centers by 2050 with profound impacts on landscapes that can act as important agents of selection. This study aims to identify 1) the net effect of urbanization on species richness, 2) how phylogenetic diversity varies between urban and rural sites, and 3) the strength of urbanization as a selection pressure. First, a meta-analysis was conducted in …

Phylogenetic Analysis And Revision Of The Nearctic Androprosopa Mik (Diptera: Thaumaleidae) With An Emphasis On The Western Species, Robert John Pivar

Masters Theses

The family Thaumaleidae, also known as seepage midges, is an uncommonly encountered, understudied family of aquatic Diptera compared to its sister group, the Simuliidae. The goal of this project was to assess species diversity of the Nearctic Thaumaleidae and determine relationships among them. The western Nearctic fauna of Androprosopa Mik is revised to include twenty-eight species, six of which are described as new to science. Descriptions of the adult males of A. apache, A. arnaudi, A. magnipelvim, A. rainierensis, A. sierra and A. uvas are provided. Redescriptions of all remaining species are also provided, as well …

A Comprehensive Evaluation Of Benthic Invertebrate Communities In The Emory River, Watts Bar Reservoir, Tn, Suzanne Jane Young

Masters Theses

The release of fly ash at the Tennessee Valley Authority (TVA) Kingston Fossil Plant (KIF) on 22 December 2008 discharged approximately 4.1 million cubic meters of coal ash into the adjacent aquatic and terrestrial systems. Previous benthic invertebrate investigations conducted by TVA and collaborative researchers concluded that benthic invertebrates in the Emory River were at moderate risk from ash-related constituents, primarily arsenic, in ash-contaminated sediment that remained in the Emory River following extensive dredging efforts. These conclusions were based on the observation of statistically significant reductions in growth and biomass in laboratory toxicity tests with Emory River sediment. Benthic invertebrate …

Exploring How Clean Water Act Enforcement Influences Stream Macroinvertebrate Communities, Shelby Renee Burks Ward

Masters Theses

Enforcement is a key feature of the Clean Water Act. The Clean Water Act’s National Pollutant Discharge Elimination System (NPDES) permit program regulates effluent into streams that may impact aquatic life. Yet, authorities do not always enforce permits when violations occur. My research examines macroinvetebrate survey data near NPDES permitted facilities in Kentucky and Tennessee to determine the influence of enforcement actions on aquatic biodiversity. Pre-existing data from the Environmental Protection Agency and state agencies was used to make quantitative and spatial comparisons.

My first study used multiple regression to explore whether enforcement and freshwater community indicators changed together. North …

Predicted 25-Hydroxyvitamin D Score And Risk Of Multiple Sclerosis In U.S. Women, Alexandra Purdue-Smithe

Masters Theses

Multiple sclerosis (MS) is a progressive, autoimmune neurodegenerative disorder affecting nearly 350,000 people in the United States and resulting in significant disability. As an immunomodulator, vitamin D may play a role in the development of MS. Previous studies have observed an inverse association of 25-hydroxyvitamin D (25(OH)D) levels and MS risk in younger populations; however, whether this relationship persists in older adults remains unclear. We prospectively investigated the association between predicted 25(OH)D level and incident MS in the Nurses’ Health Study (NHS) (n=121,701) and NHS II (n=116,430). 25(OH)D levels were predicted using validated regression models that include important determinants of …

Documenting Annual Differences In Vegetation Cover, Height And Diversity Near Barrow, Alaska, Timothy Frederick Botting

Masters Theses

Vegetation in the Arctic has been shown to respond to climate change. Documented changes have the potential to result in numerous ecosystem consequences. Therefore, understanding vegetation change is of great importance. This study documents changes in tundra vegetation with a focus on understanding the influence of annual differences in weather. Vegetation was sampled using a point frame method on 98 1-m² plots in 2010 and 2013 near Barrow, Alaska. A subset of 30 of these plots was also sampled in 2012 and 2014. Plant encounters were identified to species and grouped into one of the following functional groups: bryophytes, …