Physical Sciences and Mathematics Commons^™

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 …

Antibiotics And Antibiotic-Resistant Bacteria In Coastal Plain Streams, Jason Duff

Electronic Theses and Dissertations

Streams across the United States and globally are influenced by environmental contamination, including antibiotics, which enter streams due to widespread use and multiple pathways into the environment. Antibiotics are also likely to enter streams in mixture with other contaminants that alter the effects on aquatic organisms. Furthermore, antibiotic-resistant bacteria enter streams through similar pathways as antibiotics with implications for natural microbial communities. Therefore, understanding the presence and effects of antibiotic-contaminant mixtures and antibiotic-resistant bacteria in streams is important for resource management.

Chapter one describes an experiment that tested the hypothesis that the antibiotic tetracycline (TC) alone influences phytoplankton communities differently …