Physical Sciences and Mathematics Commons^™

Living Upstream: Kennebec River Influence On Nutrient Regimes And Phytoplankton Communities In Harpswell Sound, Siena Brook Ballance

Honors Projects

Phytoplankton underpin marine trophic systems and biogeochemical cycles. Estuarine and coastal phytoplankton account for 40-50% of global ocean primary productivity and carbon flux making it critical to identify sources of variability. This project focuses on the Kennebec River and Harpswell Sound, a downstream, but hydrologically connected coastal estuary, as a case study of temperate river influence on estuarine nutrient regimes and phytoplankton communities. Phytoplankton pigments and nutrients were analyzed from water samples collected monthly at 8 main-stem rivers stations (2011-2013) and weekly in Harpswell Sound (2008-2017) during ice-free months. Spatial bedrock and land use impacts on river nutrients were investigated …

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 …

Application Of Molecular Pathology Techniques To Understand Mechanisms Of Disease In Smallmouth Bass, Heather Leigh Walsh

Graduate Theses, Dissertations, and Problem Reports

In the Chesapeake Bay drainage, smallmouth bass Micropterus dolomieu are used as an indicator species of estrogenic contaminant exposure and have been implicated in fish kills and disease since 2005. In the Potomac River drainage, adult smallmouth bass have experienced mortality and disease and males have a high prevalence of intersex (testicular oocytes). Conversely, in the Susquehanna River drainage mortalities and disease of young-of-the-year smallmouth bass (YOY SMB) have occurred and resulted in a population shift to older and larger fish. The exact cause of these events remains unknown; however, factors such as poor water quality, contaminants, pathogens and parasites, …

Agricultural Intensification In The Midwest: Impacts On Regional Surface Humidity, Andrew Hill

All Graduate Theses, Dissertations, and Other Capstone Projects

An overwhelming majority of anthropogenic climate change studies have placed emphasis on biogeochemical agents, chiefly carbon dioxide emissions, which operate on a global scale. Fewer studies focus on biophysical factors such as land use/ land cover which operate on a regional or local scale. The impact from biophysical factors will continue to be reinforced with a growing human population and expanding resource demands. Of these factors, agricultural land use represents one of the largest, most extensive, and vital land use allocations.

The U.S. Midwest, dominated by rain-fed corn and soybean agriculture, is a key agricultural region which is lacking in …

Understanding Effects Of Changes In Land Use, Environmental Parameters, Habitat Characteristics On The Great Basin Aquatic Invertebrates Using Ecological Stoichiometric Theory, Knut Mehler

UNLV Theses, Dissertations, Professional Papers, and Capstones

Many freshwater ecosystems in the Great Basin have undergone dramatic alteration over the past decades due to groundwater withdrawal, water diversion and changes in land use. These changes have affected benthic food web dynamics by altering the availability of chemical key elements for primary and secondary producers, by loss of biodiversity and extinction of endemic species. However, only few studies are available that addresses the link between changes in land use, habitat characteristics and its effects on benthic macroinvertebrates (BMI) communities comprehensively and little attention has been given to integrating physiochemical aspects to link ecosystem functions.

This dissertation analyzes the …