Master of Science (MS), Bowling Green State University, 2022, Biological Sciences

Surface water samples, collected on the U.S. EPA Research Vessel Lake Guardian at ice-free sampling stations across Lake Erie on April 7 and 8, 2018, provided a snapshot of the composition of the lower food web, it's functionality and the physicochemical environment aimed at examining the mechanisms that drive diatom fitness and factors that affect their seasonal contribution to recurring hypoxic conditions in the hypolimnion of the Lake Erie central basin. TN:TP and DIN:TP molar ratios were conversely deficient in the western and central parts of the lake, with the more bioavailable, dissolved inorganic nitrogen deficiency occurring in the central basin. P deficiency occurred for both TN:TP and DIN:TP ratios the eastern basin. Si:TP indicated Si deficiency (<16) in the central basin, flanked by Si-replete conditions in the western and eastern basins. KEGG GhostKOALA taxonomic analysis of station ER42 surface water indicated that diatoms were less abundant at 0.51% than diatom predators such as copepods (Arthropoda) and dinoflagellates (Alveolata) at 7.22% and 2.27% respectively, suggesting spring predation could have been a factor contributing to the fate of the bloom. Parasitic oomycetes, however, were slightly less abundant than diatoms at 0.47%, and chytrids were undetected in the sample. Metatranscriptomic analysis from surface net tow samples at six EPA stations revealed twelve diatom genes exhibiting high expression (TPM ≥ 1001) from KEGG PATHWAY database categories Glycolysis/Gluconeogenesis, Biosynthesis of Cofactors, Photosynthesis, Ribosome and RNA Transport, Phagosome, and Protein Processing. Gene expression involving ribosomal translation was also high and comprised 35% of total gene expression for the Genetic Information Processing pathway, while total expression for replication and transcription was comparatively low. Total gene expression for the five sampling stations in the central and eastern basins was highest at ER15M in the eastern basin, where (open full item for complete abstract)

Committee: George Bullerjahn Ph.D. (Advisor); Paul Morris Ph.D. (Committee Member); Robert Michael McKay Ph.D. (Committee Member) Subjects: Biology; Microbiology

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2006, Biological Sciences

Low Fe availability constrains algal primary production in numerous oceanic provinces. Although not numerically abundant, the diatom microplankton (> 20 micro m) are important contributors to new production in these regions. To better understand the contributions made to new production by diatoms in Fe-depleted waters, this dissertation work addressed the Fe-specific physiological and biochemical autecology of this group. A field component consisted of two research cruises in 2002 and 2003 along a transect at 29 degrees North spanning the eastern half of the Central North Pacific (CNP) gyre, and focused on the vertically migrating bouyant giant diatom genera Rhizosolenia spp. and Ethmodiscus spp. The lab component examined physiological, biochemical and growth responses of large open-ocean and coastal diatom isolates to perturbations of Fe in the growth medium. Whereas mats of Rhizosolenias howed elevated values (ca. 0.61, n = 88) of Fv/Fm, a measure of photochemical energy conversion efficiency, along the easterly transect from Hawaii to San Diego, a clear decline in this parameter measured at locations west of 165 degrees West provided physiological evidence of nutrient limitation. By contrast, cells of Ethmodiscus showed consistently near maximal values of Fv/Fm (ca.0.7, n = 70). The higher Fv/Fmassociated with Ethmodiscus was supported in part by an enhanced Ferredoxin Index (Fd Index), a common biochemical measure for Fe status. By comparison, the Fd Index for Rhizosolenia along the western reaches of the transect was consistently depressed. Cellular Fe quotas of both diatoms rinsed with oxalate, a reagent used to reduce cell surface adsorbed Fe facilitating its removal from the cell surface, demonstrated comparable low Fe:C stoichiometry (means of 5.41 SE 4.76 and 9.21 SE 5.10) (micro mol:mol) for Ethmodiscus and Rhizosolenia, respectively. This was consistent with the presumed low dissolved Fe content of these ultraoligotrophic waters. These cellular Fe quota (open full item for complete abstract)

Committee: Michael McKay (Advisor) Subjects:

MS, University of Cincinnati, 2024, Arts and Sciences: Geology

The hydrogen isotopic composition (δ2H) of lipid biomarkers extracted from lake sediment serves as a valuable tool for tracking changes in the hydrologic cycle by reflecting changes in the δ2H of their source water. However, interpreting these changes is complicated by the mixture of terrestrial and aquatic lipids preserved in lake sediments, which present δ2H values influenced by different source waters (i.e. precipitation and lake water). Highly branched isoprenoids (HBI) produced by diatoms are suggested as a proxy for lake water hydrogen isotopic composition (δ2Hlw) that avoid terrestrial interferences. The controls on hydrogen isotope fractionation between HBI and its lake water source (ε2HHBI/lw) must be better constrained to improve the utility of HBI as a proxy for δ2Hlw. Here we measure ε2HHBI/lw across a broad study area comprising 48 lakes spanning 10 US states. We analyzed sediment, water filter, and sediment trap samples to evaluate the consistency of ε2HHBI/lw across the study area and identify factors controlling its variability. We observed a consistent and significant disparity in ε2HHBI/lw between sediment and water filter samples, suggesting that sedimentary ε2HHBI/lw values are not solely dictated by the hydrogen isotopic composition of HBI (δ2HHBI) in the water column during the sampling season (May-June). Furthermore, consistent with prior smaller-scale studies, we observed a standard deviation of ±30‰ in ε2HHBI/lw across the study area, comparable to that of widely accepted precipitation proxies such as plant waxes. These results demonstrate that δ2HHBI can be used to track changes in δ2Hlw through time. They also show that the effectiveness of δ2HHBI as a tool for reconstructing paleohydrology can be improved by developing a set of criteria to enable carful site selection that targets lakes with more consistent ε2HHBI/lw values, which are best suited for such studies.

Committee: Aaron Diefendorf Ph.D. (Committee Chair); Dylan Ward Ph.D. (Committee Member); Thomas Lowell Ph.D. (Committee Member) Subjects: Geology

Master of Science, University of Toledo, 2023, Geology

Over the past ~ 200 years, land-use changes, such as intensive agriculture and urbanization, have affected primary production in West Lake Okoboji (WLO). Lake productivity refers to the amount of energy converted to organic matter that occurs within a lake ecosystem. Thus, understanding the past productivity of WLO is necessary for reconstructing environmental changes and assessing the impacts of human activities. Here, biogenic silica (BSi) analyses and Si/Ti ratios from X-ray fluorescence (XRF) analysis were used to constrain spatial and temporal trends in the paleoproductivity in WLO. Twelve cores were retrieved from WLO, of which three cores were used to assess paleoproductivity. These three sediment cores (WLO-6, -18 and -16) were collected along a transect that includes two shallow bays and the deeper main basin of the lake. WLO-6 (~35 cm), WLO-18 (~40 cm), and WLO-16 (~35 cm) were retrieved from Millers Bay, the main basin of the lake, and Smiths Bay respectively. 210Pb was used to develop chronologies for the sediment cores using the Constant Rate of Supply (CRS) model. BSi analysis via wet alkaline digestion and meto-sulfite reduction directly quantified biogenic silica, while Si/Ti ratios provided a complementary assessment of paleoproductivity. Results of the analyses showed heterogeneity in BSi flux within and between all core analyzed. The last ~20 years showed large increases within Smiths Bay and the main basin concomitant with intensive agriculture and accelerated by urbanization in the WLO watershed. Mean BSi fluxes from WLO cores are 64.35, 102.57, and 88.38 g m-2 yr-1 for Millers Bay (WLO-6), main basin (WLO-18), and Smiths Bay (WLO-16) respectively. Additionally, our proxy analysis shows higher paleoproductivity in the main basin (core WLO-18) than in Millers (core WLO-6) and Smiths Bays (core WLO-16). Generalized Additive Models (GAMs) of Si/Ti ratios data from cores WLO-6, -18, and -16 determined periods of significant increases or reductio (open full item for complete abstract)

Committee: Trisha Spanbauer (Committee Chair); Timothy Fisher (Committee Member); Allison Stegner (Committee Member) Subjects: Environmental Science; Geology; Paleoecology

PHD, Kent State University, 2018, College of Arts and Sciences / Department of Biological Sciences

In urban streams, contaminants such as antibiotics, ARGs, nutrients, and metals, co-occur with anthropogenic activities. These toxicants can have a profound effect on microbial community composition, which may, in turn, affect microbial community function. Such results suggest that the composition and function of microbial communities are consequences of their response to environmental stimuli. However, the differing physiological responses of microorganisms to environmental stressors suggests that community structure may be an important factor driving the community's functional responses to avoid or reduce the effects associated with physiochemical changes in the environment. With the projected increase in concurrent environmental stressors associated with the anthropogenic activity, there is a need to understand how microbial communities respond to compounded stressors. The overarching question for my dissertation is: how does chemical stress (in the form of heavy metals) interact with other environmental factors (including hydrologic conditions and nutrients) to impact microbial community structure and function in streams? To address this question, I utilized a combination of trait-based molecular approaches in tandem with biological and chemical field measurements and laboratory experiments. I looked at how microbial, specifically bacterial and diatom, community composition, structure, and function were affected by different stresses that are found within urban streams.

Committee: Laura Leff (Advisor); Christopher Blackwood (Committee Member); Xiaozhen Mou (Committee Member); Elizabeth Herndon (Committee Member) Subjects: Aquatic Sciences; Biology; Ecology; Environmental Science; Microbiology

PhD, University of Cincinnati, 2005, Engineering : Materials Science

The liberation of poly(dimethylsiloxane) fluid, from the inside of silicone breast implants by diffusion and/or implant rupture, has been associated with a variety of rheumatologic disorders in patients who have received them. Continued use of these materials necessitates a better understanding of how they are created and/or utilized by biological systems. In order to determine if a fibrinogen-dependent process could play a role in the dissemination of PDMS fluid in vivo, I used histological methods in conjunction with ICP-AES to assess the dissemination of silicone droplets in normal mice and in mice lacking fibrinogen. I found that mice lacking fibrinogen had no evidence of dissemination after an administration of emulsified PDMS. In contrast, mice with normal amounts of fibrinogen showed significant evidence of dissemination, suggesting that fibrinogen has a mechanistic role on the dissemination of PDMS in vivo. I also investigated a model biological system capable of processing silicon in nature. Marine diatoms use short cationic peptides to synthesize silica. I hypothesized that if the human body was capable of silicone degradation, such peptide sequences or the key residues therein might be involved. Therefore, I characterized the reaction kinetics and resulting product morphology attributed to several silica-precipitating peptide sequences derived from the diatom Cylindrotheca fusiformis in order to better understand how biologic systems process silicon. During the course of my investigations, I used the model system to produce novel silica nano-structures and incorporate them into polymeric matrices for device application. Herein I present my research on silicon-based materials and its relevance to bioengineering. The topics covered by my research include: (1) the role of fibrinogen in the dissemination of PDMS in vivo, (2) the kinetics of silica formation mediated by cationic peptides in vitro, (3) the formation of novel silica nanostructures by those same (open full item for complete abstract)

Committee: Dr. Stephen Clarson (Advisor) Subjects:

Master of Science (MS), Ohio University, 2011, Environmental Studies (Arts and Sciences)

Acid mine drainage (AMD) is a prevalent legacy of coal mining within Appalachia. Streams receiving AMD effluent are drastically altered both chemically and biologically. Hewett Fork, a stream in southeastern Ohio, is one such affected stream. Although treatment methods have reduced acidity considerably downstream, the ability of Hewett Fork to sustain a biological community compared to those found in reference conditions remains unclear. To assess this, tiles colonized with diatom assemblages from an unimpacted stream were transplanted into Hewett Fork along a stream health gradient, from poor to good, and sampled after one, three, and six weeks in the treated stream. Chlorophyll a concentrations and species diversity metrics were calculated to compare reference assemblages to transplanted assemblages. Results suggested that after an initial one week acclimation period, assemblages at the uppermost and lowermost sites along the reach were relatively similar to those found in reference conditions, while sites within the middle region continued to show signs of impairment, although the factor(s) causing this impairment remain unknown. These findings suggest that although treatment has been effective on a site-specific basis, the expected linear-response to treatment may not be achieved due to underlying factors that are inhibiting reference-like biological communities from reestablishing within the affected stream reach.

Committee: Morgan Vis PhD (Advisor); Kelly Johnson PhD (Committee Member); Brian McCarthy PhD (Committee Member) Subjects: Aquatic Sciences; Biology; Conservation; Ecology; Environmental Science; Environmental Studies; Freshwater Ecology; Natural Resource Management; Water Resource Management

Master of Science (MS), Ohio University, 2010, Environmental and Plant Biology (Arts and Sciences)

Coal is the primary energy source for the United States and is obtained through either surface or underground mining. Prior to the 1970s there were few regulations regarding the operation and subsequent reclamation of mines and the operators were not mandated to prevent acidic mine drainage (AMD) from leaching into the local watershed. This AMD is characterized by low pH, sulfate-rich water, and high levels of dissolved metal cations. Two alkaline doser remediation projects, Monday Creek and Hewett Fork, were assessed for effectiveness by sampling the diatom assemblage structure, biofilm extra-cellular enzyme activities, and water chemistry. The diatom assemblages were examined upstream of the remediation site and at 9 locations downstream. Biofilm enzyme activities, water chemistry, and total chlorophyll a were measured at 6 locations on each stream. Based on the diatom community composition, water quality improved greatly in Hewett Fork 16.5 kilometers downstream from the remediation site, while Monday Creek remained impacted over the 41.5 kilometers sampled. The biofilm enzyme activites supported the findings of the diatom community composition in both streams studied. The Monday Creek watershed has multiple sources of AMD downstream of the remediation project, thus the effectiveness appears to be counteracted by these inputs; whereas, Hewett Fork does not have substantial downstream AMD inputs and the remediation project seems to be more effective in restoring the diatom assemblage and stream functioning further downstream.

Committee: Morgan L. Vis PhD (Advisor); Kelly S. Johnson PhD (Committee Member); Jared L. DeForest PhD (Committee Member) Subjects: Biology; Ecology; Mining

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2008, Biological Sciences

The basic ecology of wet wall algal assemblages and the ecology, distribution patterns, and taxonomy of the acidophilic diatom genus Eunotia Ehrenberg were explored from the Great Smoky Mountains National Park (GSMNP), U.S.A. First, the structural response of wet wall algal assemblages were studied through an in-field experimental manipulation of nutrients (nitrogen and phosphorus) at high and low altitudes. Subaerial algal assemblages are understudied communities and the factors that drive community dynamics in these environments are poorly understood. Algal assemblages were not as nitrogen or phosphorus limited as initially anticipated. Although not directly tested in this study, results suggested that other factors, such as ultraviolet radiation, pH, moisture levels, or microhabitat differences, are influential in shaping wet wall, algal community structure. Second, diatoms from high elevation springs and headwater streams were examined and found to be dominated by a couple of Eunotia taxa, including a new species, E. macroglossa sp. nov. The presence of morphological deformities at some of the spring sites was documented with both light and scanning electron microscopy and the malformations suggest that acid precipitation may directly be harming the aquatic ecosystems in the park. Third, the distribution patterns of Eunotia species from sites throughout the park were explored in relation to environmental factors such as elevation, pH, geology, and water chemistry. As expected higher altitude streams generally had lower pH levels and a greater relative abundance of Eunotia relative to other diatom genera, especially species in the E. exigua complex. The results highlighted how vulnerable high elevation areas in the GSMNP may be to acid precipitation. Finally, an image rich documentation and inventory of the Eunotia taxa in the GSMNP was provided, including species descriptions, morphological measurements and a discussion of taxonomic challenges. The Eunotia were (open full item for complete abstract)

Committee: Dr. Rex Lowe (Advisor); Dr. Alexander Izzo (Other); Dr. Jeffrey Johansen (Committee Member); Dr. Karen Root (Committee Member); Dr. Dan Wiegmann (Committee Member) Subjects: Biology

Master of Science (MS), Bowling Green State University, 2006, Biological Sciences

Atmospheric nitrogen pollution has been shown to cause acidification and consequent chemical shifts that have the potential to alter algal species composition in aquatic ecosystems. This study addressed the question, which physical and chemical factors along an elevation gradient have the greatest influence on benthic algal community structure in the Hazel Creek Watershed (HCW) in Great Smoky Mountains National Park? In August 2005, eight composite epilithon samples were taken from five sites in the HCW. Water chemistry data were obtained from the National Park Service. An analysis of similarities of the assemblages showed changes in algal community composition along the elevational and chemical gradient. It appears that nitrate, pH, acid neutralizing capacity, and aluminum levels are among the most influential chemical factors of algal community composition in the HCW, while water temperature and canopy cover are the most influential physical factors.

Committee: Rex Lowe (Advisor) Subjects: Biology, Ecology

Master of Science (MS), Bowling Green State University, 2013, Geology

Lake El'gygytgyn, located in Chukotka northeast Russian Arctic, contains a continuous high-resolution sediment record extending to 3.58 ± 0.04 Ma. The ICDP site 5011-1 composite core was collected in the spring of 2009. Multi-proxy studies of this lacustrine sediment core are ongoing. The goal of this research project is to investigate the relationship between diatom size and past climate and to explore its potential as a paleoclimate proxy. Valve diameter of the dominant planktonic diatoms was measured in 150 samples from 3.46 to 2.10 Ma. The results from this study indicate that diatom valve size during interglacial periods is statistically different than during glacial periods. During interglacial periods of the mid-Pliocene, the valve diameter (95th percentile) is ~43% larger than during glacial periods of the same interval. The extreme warm intervals of the mid-Pliocene (especially 3.38 to 3.35 Ma) have the largest valves measured in this study. The valve diameter (95th percentile) during the Pleistocene interglacial periods is ~12% larger than during the glacial periods of the same interval. During the late Pliocene-early Pleistocene climate transition (2.66 to 2.35 Ma), multiple size-distinctive populations of diatoms within one sediment interval occur sporadically. The exceptionally large valves during the extreme interglacial periods are consistent with conditions of potentially increased nutrient input and open water conditions during times of extreme warmth and precipitation inferred from other proxies. The size distribution of the dominant planktonic diatoms is not associated with a single environmental factor. Other climatic factors, biological controls, and taphonomic processes may have had influences on diatom valve size. Further investigations of morphological changes of other genera of planktonic diatoms in the younger record could provide a greater understanding of the links between climate and diatom size and help to characterize the diffe (open full item for complete abstract)

Committee: Jeff Snyder Dr. (Advisor); Margaret Yacobucci Dr. (Committee Member); Kurt Panter Dr. (Committee Member) Subjects: Geology