Biology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2749
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Item Characterizing nutrient budgets on and beyond farms for sustainable nutrient management(2023) Zou, Tan; Zhang, Xin; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The production and security of food are heavily reliant on adequate nitrogen (N) and phosphorus (P) inputs in agriculture. However, ineffective management of N and P from the farm to the table can result in nutrient pollution, triggering both environmental and social issues. Moreover, another important challenge for P management is limited and unevenly distributed P resources, leading to P scarcity in many parts of the world. Inefficient use of nutrients in agriculture-food systems is the root cause of both nutrient pollution and scarcity. To improve nutrient use efficiency and reduce nutrient loss, it is crucial to address key knowledge gaps in nutrient management research, which include inadequate quantification of nutrient budgets, as well as identifying and addressing nutrient management challenges across various systems and spatial scales. This dissertation tackles the knowledge gaps in two studies, including a global-scale study and a case study of the Chesapeake Bay watershed. In the global-scale study, I establish and utilize a unique P budget database to assess historical P budget and usage patterns at the national and crop type level from 1961 to 2019. This analysis reveals the impacts of various agricultural and socioeconomic drivers on cropland P use efficiency (PUE), including N use efficiency (NUE), fertilizer-to-crop-price ratio, farm size, crop mix, and agricultural machinery. The findings indicate that P management challenges vary by country and spatial scale, necessitating tailored country-level strategies. The regional-scale study applies a framework adapted from N studies to the Chesapeake Bay watershed, analyzing nutrient (N and P) management across systems and spatial scales. This approach uncovers that nutrient loss potential beyond crop farms is larger than that at crop farms. This highlights the need to enhance nutrient management and curb nutrient loss in animal production, food processing and retail, and human consumption. This study also identifies a large potential for meeting cropland nutrient demand by increasing the recycling of nutrients in manure, food waste, and human waste. To tackle the challenges surrounding nutrient management in the watershed, it is imperative to target factors significantly related to nutrient management, such as agricultural practices, soil properties, climate change, and socioeconomic conditions. This dissertation contributes to a deeper understanding of N and P management challenges, gaps, priorities, hidden drivers, and potential solutions at various scales, from regional to national and global levels. The analytical procedures and statistical tools developed in this dissertation are generalizable, allowing for their adaptation to similar nutrient management studies in different regions and for diverse research purposes.Item VALUING SHALLOW WATER SYSTEMS IN MARYLAND'S CHESAPEAKE BAY(2022) Munkacsy, Megan; Wainger, Lisa; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Oyster aquaculture (OA) activity is sometimes framed as a hindrance to habitat, recreation, property values, and wild oyster harvest in Maryland’s Chesapeake Bay. Yet, tradeoffs under OA policies have not been thoroughly analyzed. I applied decision science techniques to capture alternative OA policy effects on users and ecosystem services. Stakeholders helped organize system complexities into management goals and performance indicators and shared preferences to inform indicator weights. These weights were applied to outcomes from a suite of economic and ecological models, resulting in each scenario’s stakeholder-weighted summary score. Results revealed that (1) highly protective habitat policies create a risk to future OA production while protecting less than 0.1% of habitat, (2) proposed changes to current OA policies appear less effective at balancing goals, and (3) under no policy does OA impact more than 1.3% of wild oyster revenues. This analysis served to clarify system complexities to inform policy analysis.Item APPLIED STASIS THEORY AND Q-SORTING FOR ORGANIZING ENVIRONMENTAL SCIENCE COLLABORATION FOR POLICY DELIBERATION: A CASE OF POULTRY HOUSE EMISSIONS—AMMONIA AND PARTICULATE MATTER—ON THE DELMARVA PENINSULA/EASTERN SHORE(2022) Shea, Mary E; Tjaden, Robert; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)CONTEXT: Poultry farmers respond to national and global demand for low cost, packaged chicken. Raising poultry for market results in ammonia and poultry litter (manure and dust). However, for the Delmarva part of the Chesapeake Bay Watershed and Airsheds, ammonia and poultry litter mean nitrogen pollution, which effects water quality and human health. Therefore, this inquiry looks closely at the values and benefits that shape poultry farmer decisions about managing ammonia from their poultry houses using two technologies: Vegetated Emissions Buffers (VEBs) and Poultry Litter Treatments (PLTs). QUESTION: How can we better understand the values and benefits embodied in ammonia management choices by poultry farmers? METHODS: This dissertation uses three methods to engage with poultry farmers (2012-19) to better understand a range of values—economic and non-economic—about voluntary ammonia management strategies. 1. Stasis theory (Chapter Two), 2. Scaling of conceptual diagrams to three inch by four-inch cards, for designing visual Q-cards (Chapter Three), 3. Q-sorting of cards and findings (Chapter Four). FINDINGS: The Q-sorting events in this November 2019 study (25 value/benefits statements, sorted with 13 poultry producers) did not meet respondent number thresholds for formal Q-method factor analysis. However, results were studied using exploratory data analysis and chi-square testing of Q-sorting data. One important finding is that these eight cards appeared as important in two analysis categories: first, six cards likely MOST IMPORTANT (Photo 1); and second, the next two cards (Photo 2) as perhaps SOMEWHAT IMPORTANT. These pictured two sets of cards are ranked overall as having greater importance to poultry farmers, compared to aggregate card rankings of the other 17 cards in the 25-member card set. Photo 1: In the aggregate, these six cards were sorted most often into the MOST IMPORTANT category. Photo 2: In the aggregate, these two cards were sorted most often into the IMPORTANT category. The six cards in Photo 1 (MOST IMPORTANT) can be understood in several ways. First, these three cards (position noted in bold) represent economic benefits to poultry farmers, important for farm fiscal stability. The three cards on the left all represent health gains for chickens, meaning a better payout when healthy, unblemished, full-weight birds are sold to the poultry company:• Top-left card: This card symbolizes healthy chickens as “happy”—a visual shorthand for healthy—commanding more per pound at payout. • Middle-left card: This card shows reduced in-house ammonia, which means that chicken flesh is less likely to be burned or marred by ammonia, commanding more per pound at payout; generally, lowered in-house ammonia also means healthier birds, which is a specific value noted in just above in the top-left card description. • Bottom-left card: This card shows unblemished chicken “paws” which can command an extra premium for Asian specialty food markets. This portion of the bird represents a newer market for poultry producers. Within this group, two of these cards in Photo 1 (top- and middle-left) also show the value to farmers of using an enhanced schedule of PLTs to reduce ammonia inside the poultry house. The right-hand cards in Photo 1 can be understood thusly as relying on VEB use:• Top-right card: This card shows energy savings from using VEBs to shade poultry houses and provide winter wind cover, thereby reducing energy costs annually, supporting farm fiscal status. • Middle-right card: This card symbolizes reduced ammonia odor by VEB capture, which can help avoid neighbor and nuisance complaints. • Bottom-right card: This card shows the value of VEBs as helping the farmer meet existing nutrient management planning, a state-administered requirement for many poultry farmers. nitrogen and phosphorus are two nutrients associated with poultry production, poultry litter storage/composting, and poultry litter application as field fertilizer. These three VEB-focused cards in Photo 1 share the common context of concerning ammonia management strategies outside the poultry house, relying on the pollution remediation strategies of VEBs, a type of designed hedgerow plant structure._____ The two cards in Photo 2, noted as IMPORTANT but not as MOST IMPORTANT as the six cards in Photo 1 just described, relate to farmer concerns about human health. • Top card: This card show that poultry farmers can use VEBs outside poultry houses to capture ammonia and particle pollution, thereby improving local air quality, especially for farm families who live close to their poultry houses. • Bottom card: This card show that poultry farmers can use enhanced PLTs to reduce in-house ammonia, thereby improving worker conditions inside the poultry house. CONCLUSION: This case study demonstrates the value of Q-sorting used with Delmarva poultry farmers and attitudes about ammonia management. These findings can be also understood as ground-truthing evidence, in that the visual card-sorting data confirm as important the eight cards discussed above. These values/benefits depicted on these cards fit the poultry context of the Chesapeake Bay ecosystem. Additional Q-sorting activities with these cards or revised card sets to meet research needs are worthy undertakings. This dissertation case study also shows the value of humanities within environmental policy deliberation. Stasis theory, from rhetorical studies, helped organize the complexity of this project, as well as made a clear role for valuing activities (including Q-sorting). A second field of humanities inquiry is science visualization studies. This field, closely allied with rhetoric, helped with design values to build clear and environmentally-situated picture cards for Q-sorting the ranked importance of these cards to poultry farmers. Finally, the last chapter reflects on ways that a human dimensions approach supports a re-imagined Delmarva poultry production. One central design criterion about poultry production futures centers the role of poultry farmers, especially young farmers, in planning for resiliency. Among the pressures on poultry production is the well-documented wetter and warmer Delmarva, to climate change. The COVID-19 pandemic due to the 2019 emergence of the SARS-CoV-2 virus, also posed risks to Delmarva poultry resiliency. Scenario analysis and design options are better with humanist and social science knowledge, combined with environmental science.Item Using citizen science to collaboratively research and manage Chesapeake Bay(2021) Webster, Suzanne E; Dennison, William C; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Chesapeake Bay is a complex socio-ecological system with an equally complex adaptive management program. The environmental management community has expressed a need for more local-scale environmental data and increased stakeholder engagement in Bay restoration efforts. Although citizen science has the capacity to meet both of these needs, participatory research is currently underused and undervalued. Additional research is needed to help Chesapeake Bay environmental stakeholders develop and leverage citizen science partnerships to accomplish diverse research and management goals. This dissertation explored various challenges that limit the use and potential impact of citizen science in Chesapeake Bay. Three distinct studies were conducted to gain a more complete understanding of stakeholders’ perceptions and experiences concerning public engagement in scientific research. These studies employed several qualitative and quantitative approaches, including interviews, participant observation, surveys, and cultural consensus analysis. This research provided evidence of widespread agreement that diverse stakeholder concerns should be more prominent in management decisions. Research also found shared feelings of disempowerment across the Chesapeake environmental community. Environmental stakeholders appreciated that science plays a central role in informing environmental policy, but they had mixed perspectives on the utility of citizen science. This research found an underlying cultural understanding of environmental monitoring that provides a foundation for collaboration among stakeholders with different priorities. These findings indicate that citizen science programs can a) serve as boundary spanning organizations that help stakeholders foster a more cooperative mentality, b) allow diverse groups to strategically work together to accomplish goals, and c) increase the impact of volunteer-collected data on Chesapeake science and management. This research also showed that using a transdisciplinary approach to citizen science can increase stakeholders’ feelings of engagement, improve perceptions of a program’s overall credibility, and increase the program’s overall likelihood for impact. The results of this place-based study in the Chesapeake region are also broadly applicable to other socio-environmental systems. This dissertation provides evidence-based support for continued and expanded stakeholder engagement in environmental science and management and offers specific recommendations to support more collaborative, productive, and empowering citizen science partnerships that inform holistic and innovative environmental management decisions.Item NUTRIENT RETENTION BY RIPARIAN FORESTED BUFFERS IN WESTERN MARYLAND: DO THEY WORK AND ARE THEY WORTH IT?(2021) Siemek, Stephanie Melissa; Eshleman, Keith N; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Riparian buffers are a best management practice (BMP) implemented to improve water quality. In 1997, Maryland established the Conservation Reserve Enhancement Program (CREP) to give landowners incentives to install riparian buffers that would help restore the Chesapeake Bay. Although many studies support riparian buffers as a BMP, many have also reported a wide range of nutrient reductions. It is uncertain what factors control buffer function, yet they continue to be installed with high expectations. Water quality predictions become less accurate in hydrogeologically complex systems such as the Ridge and Valley (R&V) physiographic province. The purpose of this research was to assess the riparian buffer’s nutrient removal function of dissolved nitrogen and phosphorus in the R&V to understand the hydrologic controls further. Throughout western Maryland, we conducted two synoptic stream chemistry studies that contained forest buffers planted under CREP and a range of pre-existing natural forested riparian zones. We used a steady-state reach mass balance model to estimate lateral groundwater inputs and tested several nutrient models to describe the nutrients in groundwater discharge. We then aimed to understand if incentives given through CREP to landowners were adequate by performing a benefit-cost analysis (BCA) using three scenarios. We used the BCA results to estimate nutrient reduction costs using results from the Chesapeake Bay Watershed Model (CBWM) and our synoptic studies. Streams along CREP sites did not show strong evidence of nutrient retention. However, those containing a mix of natural forests with planted buffers showed significant nutrient declines in both synoptic studies. Several models tested (i.e., The Nature Conservancy model, Gburek and Folmar (1999), our base model) inadequately described nutrient discharge; however, our actual flow model performed best. Our BCA results found newly planted forest buffers under CREP provide the greatest financial gains to landowners, but grass buffers are the most cost-effective practice based on CBWM’s estimated nutrient reductions. Although our research did not assess grass buffers, our synoptic studies showed little indication that newly planted forest buffers significantly reduce nutrients in the R&V, suggesting stream water quality greatly depends on the watershed’s hydrogeomorphology that controls how major contributing sources filter through the landscape.Item Nutrients, chlorophyll, and emergent harmful algal bloom species of concern in coastal waters of Assateague Island National Seashore(2021) Ross, Morgan O; O'Neil, Judith M; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The Atlantic Ocean coastal zone of Maryland is important both ecologically and economically. Due to water quality issues, the coastal lagoons of Maryland have received considerable research attention, but little corresponding research in the coastal waters that exchange with the coastal lagoons. To better understand the linkages between the coastal ocean and the potential impacts of human activity on Maryland’s coastal zone, 5 research cruises (2018-2019) were completed to investigate concentrations of nutrients and emergent harmful algal bloom (HAB) species of concern (Dinophysis, Karenia, Pseudo-nitzschia). Nutrient and HAB species had high intra-annual variability, as well as geographic variability with relation to the inlets, coastal lagoons, and offshore discharge sites. The most significant determinants across all sampling locations, depths, and times were nitrate and ammonium. Continued eutrophication and climate change, as well as the impact of connected waterways, presents challenges for managing regional water quality issues in the coastal ocean.Item THE ROLE OF SOCIO-ENVIRONMENTAL REPORT CARDS IN TRANSDISCIPLINARY COLLABORATION AND ADAPTIVE GOVERNANCE FOR A SUSTAINABLE FUTURE(2020) Nguyen, Vanessa Vargas; Dennison, William C; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Addressing sustainability challenges and overcoming environmental problems requires fundamental societal changes. However, communicating these issues and convincing people to act is challenging. One emerging science communication tool that can accommodate this need is boundary-spanning report cards. Report cards were originally used as a tool for assessing and communicating ecosystem health conditions, but there are a growing number of report cards that incorporate socio-economic values. My dissertation focuses on investigating the role of socio-environmental report cards in addressing sustainability challenges. My research question was centered around whether considering human dimensions and understanding the links between natural and social components of socio-environmental systems can lead to a productive collaboration. This collaboration can lead to positive actions that contribute to a sustainable future. My research has two major themes:1) Evaluation of report cards and 2) Evolution of the report card process. First, I found that report cards from a diversity of locations can lead to environmental literacy and promote sustainable actions and positive environmental change. Then, using the Mississippi River Watershed report card as a case study, I demonstrated that report cards are boundary objects that can serve as a platform for transdisciplinary collaboration and serve as a catalyst for collective action. I also established that various report cards in the Chesapeake Bay watershed were able to enhance adaptive governance by facilitating continual learning and cross-scale exchange of information between different organizations. My results highlighted the evolution of report cards from a product created to increase awareness and education about environmental issues, to a process that engages stakeholders. My conclusion is that report cards should include both social and environmental indicators and the process needs to be stakeholder-driven and action-oriented. I developed a framework and a theory of change to guide how socio-environmental report cards can address sustainability challenges and applied it in the Chesapeake Bay watershed. By creating a holistic assessment that balances environmental, economic, and social concerns, socio-environmental report cards incorporate multiple perspectives from multisectoral actors. Thus, socio-environmental report cards can enhance adaptive governance and provide the foundation for collaborative solutions for sustainable resource management.Item TROPHIC ECOLOGY AND PHYSIOLOGICAL CONDITION OF BLACK SEA BASS CENTROPRISTIS STRIATA IN THE MIDDLE ATLANTIC BIGHT(2018) La Rosa, Ginni Alice; Woodland, Ryan J; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Black sea bass Centropristis striata (Linnaeus, 1758) is a valuable Middle Atlantic Bight fisheries species, but spatial patterns in condition and diet during summer residence at inshore reefs remain largely unknown. I examined a suite of potential drivers of physiological condition and trophic niche of C. striata using morphometric, stomach contents, and stable isotope indicators. Regional differences in liver tissue lipid content and standard condition indices covaried with additional biotic and abiotic factors. I show that liver tissue must be corrected for lipid content prior to interpreting liver carbon stable isotope data and I provide a correction equation for this species. Both spatial and biological factors explained observed patterns in diet and trophic niche metrics. An understanding of the factors that underlie spatial and temporal patterns in condition and trophic ecology provides insights necessary to help inform ecologically-focused management decisions.Item Effects of urbanization and infiltration-based watershed restoration on the hydro-ecology of headwater streams(2016) Fanelli, Rosemary Margaret; Palmer, Margaret; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Urbanization profoundly alters the hydrologic routing of a landscape resulting in the degradation of downstream aquatic ecosystems. To mitigate these effects, watershed managers implement infiltration-based storm water control measures (SCMs), designed to convert stormwater runoff into groundwater recharge. However, the ability of infiltration-based SCMs to restore hydrological processes, and to reverse damage to the downstream ecosystem, remains poorly understood. To address this research gap, I examined the hydro-ecological effects of urbanization and SCM implementation in 11 headwater watersheds spanning an urbanization-restoration gradient (4 forest, 4 urban-degraded, and 3 urban watersheds restored with SCMs) near Annapolis, Maryland, USA. Regenerative stormwater conveyances (RSCs) were the type of SCM examined in the study. I used high-frequency precipitation, stream stage, and baseflow discharge collected at the watershed outlets to develop metrics characterizing watershed storage and stream responses to precipitation. I then conducted water quality sampling, temperature monitoring, and quantified aquatic insect community composition in the downstream ecosystems. Finally, I employed high-frequency groundwater monitoring in one of the SCMs to identify potential mechanisms controlling their hydrological function. The hydrological effects of urbanization were clearly observed across the study watersheds, but only one of the three restored watersheds modulated hydrology (e.g., a larger minimum runoff threshold relative to the other urban watersheds). However, baseflow in this stream was low compared to the forested streams, suggesting that enhanced infiltration of stormwater runoff did not recharge storage zones that support stream baseflow. Aquatic insect diversity and the percentage of sensitive taxa declined with increasing urbanization, with no significant effect of restoration. Water quality remained poor in both urban-degraded and urban-restored streams, with higher conductivity values, lower dissolved oxygen, and warmer stream temperatures than in forested streams. These water quality issues likely hampered recovery of sensitive taxa in downstream ecosystems. Groundwater monitoring in one of the SCMs indicated that high runoff delivery rates from the watershed limited infiltration within the SCM, which allowed the conveyance of untreated runoff to the downstream channel. The centralized design of RSCs, and their placement in areas of topographic convergence above channel heads, likely limits their effectiveness for restoring hydrological processes to urban watersheds.Item The effect of aquaculture gear and tidal zone on the growth and shape of the oyster Crassostrea virginica during a “finishing period” in Chesapeake Bay.(2016) Thomas, Laura Landis; Plough, Louis V; Cornwell, Jeffrey C; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study investigated how aquaculture gear type and increased wave action influenced growth and shape of eastern oysters Crassostrea virginica during a “finishing” period in Chesapeake Bay. Oysters were deployed in three different gear treatments in the intertidal or upper water column: bottom cages, OysterGro™ floats, and rack and bag, and a bottom cage was also deployed in the subtidal zone as an industry control. Shell length(L), width(W), height(H), total weight and wet meat weight were measured each month from August to December 2015 and an index of shell shape (deviation of L-W-H from idealized 3-2-1 ratio) calculated. OysterGro™ floats produced the greatest increase in wet and total weight and the most ideal shaped oysters (lowest 3-2-1 ratio deviation). Overall, these results demonstrate the benefit of deploying oysters in higher wave action gear types such as the OysterGro™ and will increase the available data on gear performance in Chesapeake Bay.