Master of Science (MS), Ohio University, 2016, Plant Biology (Arts and Sciences)

Acid Mine Drainage (AMD) from pre-regulation mining affects streams in the Appalachian region resulting in acidic waters with high dissolved metal content. Previous studies have shown remediated stream segments have better water quality and biological communities than untreated streams, but these segments have not attained the same biological quality as streams unaffected by AMD. Phosphorus limitation of the biofilm community has been hypothesized as a contributing factor. Nutrient limitation was tested in four stream categories using nutrient diffusing substrates: AMD, transitional, recovered and unimpacted. Chlorophyll a, a measure of photosynthetic biomass, was significantly higher in phosphorus treatments. In addition, the phosphorus treatments had lower phosphorus-acquiring enzyme activities compared to the control. The phosphorus with nitrogen treatment showed an increase in polyunsaturated fatty acids, having higher nutritional value for grazers. This study demonstrated that nutrient availability has a substantial impact on the photosynthetic component of biofilms in impaired and remediated streams.

Committee: Morgan Vis (Advisor); Jared DeForest (Committee Member); Kelly Johnson (Committee Member) Subjects: Ecology; Freshwater Ecology

Doctor of Philosophy (PhD), Ohio University, 2016, Plant Biology (Arts and Sciences)

Acid mine drainage (AMD) is a consequence of historical and present day mining activities. Remediation efforts are frequently successful in improving water quality with elevated pH and decreased dissolved metals. In many streams, there has been chemical and biological recovery. The goal of restoration is to improve both biological communities and processes within the stream. I compared biofilm community structure (using fatty acid profiles), function (primary production, extracellular enzyme activity), and food web structure from three stream categories in southeast Ohio: streams impaired by acid mine drainage, streams that have undergone remediation of AMD impairment, and streams that have not been impaired by AMD. I hypothesize that remediated streams will be more reliant on terrestrial sources of energy due to nutrient limitation of benthic biofilms. Fatty acid profiles (PLFA and total fatty acids) identified distinct biofilm communities associated with AMD-impaired streams or AMD-remediated and AMD-unimpaired streams and showed that these biofilm communities were not different throughout the sampling season. I found that the lowest rates of benthic biofilm gross primary productivity and primary producer biomass (chlorophyll a) were in the impaired streams while AMD-unimpaired streams had the highest. Biofilm production and primary producer biomass in streams that were classified as remediated were in between impaired and unimpaired and not statistically different from either. Results of carbon and nutrient acquiring extracellular enzyme activities suggest that phosphorus availability is limiting production and biomass in the impaired and remediated streams, probably as a result of metal precipitates associated with AMD readily binding with biologically available forms of phosphorus. Invertebrate carbon and nitrogen isotopic analysis showed that two invertebrate predators (Nigronia sp. and Boyeria sp.) had lower reliance on autochthonous basal resources and (open full item for complete abstract)

Committee: Morgan Vis (Advisor); Kelly Johnson (Committee Member); Jared DeForest (Committee Member); Brian McCarthy (Committee Member) Subjects: Freshwater Ecology

PHD, Kent State University, 2013, College of Arts and Sciences / Department of Biological Sciences

It is important to understand fate of nutrients like nitrogen, in streams given that anthropogenic activity, such as agriculture, have increased inputs of biologically reactive nitrogen to the environment leading to deterioration of stream health and eutrophication. Bacteria play a crucial role in the driving essential biogeochemical transformations. The purpose of this research was to improve our understanding of organic and inorganic nitrogen utilization by bacterial isolates and complex bacterial communities. Role of bacterial diversity in resource utilization is mostly neglected in biogeochemical models. Identification of bacteria based on molecular methods, like 16S rDNA sequencing, yield a wealth of information related to prokaryotic diversity and its importance in driving essential biogeochemical cycles. In this research utilization of organic and inorganic forms of nitrogen by stream heterotrophic bacterial isolates were examined. Our results reveal differences in bacterial resource utilization not as a function of the different taxa involved but of the enrichments the isolates were obtained from, as immediate environment dictate bacterial response to different nutrients and exerts a selection pressure. Carbon availability also influences nitrogen dynamics. To examine the impact of carbon on bacterial uptake of organic and inorganic nitrogen, bacterial abundance and community composition were examined in controlled, laboratory microcosms. There was a strong influence of carbon availability on bacterial nitrogen utilization, with preferential uptake of organic forms under low carbon concentrations. Carbon and nitrogen treatments likely drove changes in bacterial community composition that, in turn, affected rates of nitrogen utilization under various carbon concentrations. Metabolic functions, such as particular biogeochemical reactions are catalyzed by microbial extracellular enzymes, which are likely linked to the constituting taxa in a given microbial comm (open full item for complete abstract)

Committee: Laura Leff (Advisor); Christopher Blackwood (Committee Member); Christopher Woolverton (Committee Member); Anne Jefferson (Committee Member); Michael Tubergen (Other) Subjects: Biology; Ecology; Microbiology