UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item REFINING METAGENETIC ENVIRONMENTAL DNA TECHNIQUES FOR SENSITIVE BEE COMMUNITY MONITORING(2023) Avalos, Grace; Richardson, Rodney T; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Molecular taxonomic detection is now widespread across the sciences, because of advances in direct PCR, improved marker selection, and increases in sequencing throughput. Facilitated by these advances in sequencing, methodological sensitivity of sample identification has improved substantially. Metagenetic techniques to infer what species are present in a sample by sequencing unknown samples and comparing them to known references has the potential to advance our understanding of biodiversity. Metagenetic analysis of environmental DNA (eDNA) represents a novel, non-lethal method for characterizing floral-associated arthropod communities. Diverse arthropod assemblages interact with flowers, and floral surfaces have been shown to harbor arthropod DNA. We performed metagenetic sequencing on eDNA isolated from flower samples and honey bee-collected pollen samples using multiple markers and compared the frequency and taxonomic breadth of eDNA detections across these genetic markers and substrate types. Understanding which markers and substrates are most effective for eDNA characterization of floral-associated arthropod communities will guide future research and enable low-risk detection of threatened or endangered arthropods.Item Investigating the Utility of Environmental DNA Analysis for the Monitoring and Management of Mid-Atlantic Alosine Fishes(2023) Fowler, Chelsea; Plough, Louis V; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Environmental DNA (eDNA) tools can address gaps in fish assessment data while reducing the cost and the impact of sampling on threatened anadromous alosine fishes in Chesapeake Bay. Here, I tested the ability of high-frequency eDNA sampling of river herring to predict fish abundances from sonar-based fish counts on the Choptank River and developed and validated novel species-specific eDNA assays for American and hickory shads. River herring eDNA concentrations from daily eDNA sampling were highly correlated to sonar-based fish counts (Spearman’s Rho = 0.84). This relationship informed a model that could accurately predict fish count from eDNA and relevant covariates (R2 = 0.88). The two new shad assays are highly specific and quantitative, and field testing validated detections in Delaware, Maryland, and North Carolina. This work provides a set of eDNA monitoring tools for the Mid-Atlantic alosines and highlights the capacity for eDNA data to generate quantitative metrics of fish abundance.Item Assessing vertebrate biodiversity across the Chesapeake Bay using environmental DNA metabarcoding(2023) Rodriguez, Lauren Kelly; Bailey, Helen; Woodland, Ryan J; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Through the collection and sequencing of trace genomic evidence from environmental samples (e.g., water, air, and soil), environmental DNA (eDNA) metabarcoding can detect a range of vertebrates. Despite the dynamic characteristics of estuarine environments, which often hinder the persistence of genomic material, this project successfully employed metabarcoding to assess the distribution of vertebrates in the Chesapeake Bay. Primarily, the study evaluated the effects of using various eDNA sampling, laboratory, and post-hoc analysis techniques when investigating species presence and biodiversity of an area. This study also identified spatially-explicit fish communities along salinity gradients as described by a Generalized Additive Mixed Model (GAMM) and a Permutational Multivariate Analysis of Variance (PERMANOVA). Community compositions were similar to previous findings by traditional trawling and seining methods. This research supports the usefulness of eDNA metabarcoding to assess species presence across spatiotemporal extents, making it a promising tool for future biomonitoring efforts in the Chesapeake Bay.