Fresh Water Studies Commons^™

Paleoenvironmental Reconstruction Of Quaternary Saltville, Virginia, Using Ostracode Autecology, Austin Gause

Electronic Theses and Dissertations

The Saltville valley in southwestern Virginia is home to Quaternary localities containing paleontological and archaeological remains. Historically the valley has been mined for salt and the small lakes, ponds and springs along the valley floor have a brackish signature. A preliminary report on the site’s ostracode fauna suggested that the site’s water was not always saline. This study analyzed modern and Quaternary ostracodes to understand the valley’s hydrologic and chemical evolution. Sediments contained primarily freshwater species, including the environmentally sensitive Candona crogmaniana. The presence of Pelocypris tuberculatum and a new Fabaeformiscandona species throughout a vertical section spanning the latest Pleistocene …

Improved Estimates Of Tributary Nitrogen Load To Casco Bay, Maine, Whitley J. Gray

Electronic Theses and Dissertations

Over the past two decades, total nitrogen (TN) concentrations have increased in Casco Bay (CBEP 2015). The sources of the increased nitrogen are poorly understood but occur with simultaneous population growth and land use changes. The total riverine nitrogen load to Casco Bay was previously estimated by Liebman and Milstead (2012) using the United States Geologic Survey’s (USGS) SPAtially Referenced Regression On Watershed attributes (SPARROW) model. The SPARROW model uses watershed characteristics, regional monitoring data and nitrogen source data to estimate nitrogen loading but was not validated using measurements of nitrogen in the Casco Bay watershed. This study attempts to …

Three-Dimensional Bedrock Channel Evolution With Smoothed Particle Hydrodynamics, Nick Richmond

Electronic Theses and Dissertations

Bedrock channels are responsible for balancing and communicating tectonic and climatic signals across landscapes, but it is difficult and dangerous to observe and measure the flows responsible for removing weakly-attached blocks of bedrock from the channel boundary. Consequently, quantitative descriptions of the dynamics of bedrock removal are scarce. Detailed numerical simulation of violent flows in three dimensions has been historically challenging due to technological limitations, but advances in computational fluid dynamics aided by high-performance computing have made it practical to generate approximate solutions to the governing equations of fluid dynamics. From these numerical solutions we gain detailed knowledge of the …

Evaluating Potential For Water Quality Decline In Maine Lakes, Kaci N. Fitzgibbon

Electronic Theses and Dissertations

Understanding lake vulnerability with respect to eutrophication and loss of water quality is important for sustainability of aquatic ecosystems. This project aims at identifying and quantifying the effects of relevant physiochemical, climate, and watershed characteristics on lake vulnerability in order to develop management decision tools for the Maine Department of Environmental Protection (MEDEP). In a changing chemical and physical environment, using independent variables from each of these categories and then relating them to the summer lake epilimnetic phosphorus (P) concentrations allows for development of models to inform stakeholders of lake vulnerability to eutrophication problems.

We studied 24 lakes covering a …

A Paleolimnological Assessment Of Three Oligotrophic Watersheds In Maine, Tiffany Ann Wilson

Electronic Theses and Dissertations

Phosphorus (P) is a limiting nutrient in aquatic ecosystems. Its bioavailability determines the trophic status of lakes. The biogeochemistry of P in surface waters can be controlled by a combination of abiotic and biotic factors. Dissolved inorganic aluminum (Al) and iron (Fe) hydrolyze in streams and lakes to produce Al(OH)₃ and Fe(OH)₃ in the water column. These hydroxides may also form through photo-oxidation of complexes with DOC, liberation of inorganic metal species, and precipitation, followed by sedimentation. These solid phases readily adsorb P from the water column, reducing the amount that is available for biological nutrition (Kopácek et …

Relationships Between Stream Geomorphology And Fish Community Structure And Diversity In Maine, Emily Gaenzle

Electronic Theses and Dissertations

Predicting patterns in species distribution and abundance for resource management and conservation is a major focus of applied ecology. The primary objective of this study was to determine if there is a predictable relationship between stream geomorphology and fish community structure, native species richness, and native salmonid abundance in Maine. Specifically, I examined relationships between fish assemblages and geomorphic stream types, as delineated by the Rosgen classification system (Rosgen 1996). Fifty-three stream reaches in Maine were classified, and fish communities within the reaches were characterized using backpack electrofishing. Species richness was lowest in A-type streams (i.e., steep, entrenched, confined), which …