Biology
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Item MESOSCALE EDDIES INFLUENCE ZOOPLANKTON DISTRIBUTION AND GRAZING IN THE GULF OF MEXICO(2024) Atkinson, William August; Coles, Victoria J.; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Carbon biomass and net primary productivity, for two size classes of phytoplankton in the Gulf of Mexico (GoM), are calculated from ocean color remote sensing data. Combining these estimates with mechanistic ecosystem model equations allows for analysis of how changes in phytoplankton biomass and community structure propagate through the food web to zooplankton. Biomass and grazing rates are calculated for three size classes of zooplankton (small, large, and predatory) by solving equations from the NEMURO model describing the growth of small and large phytoplankton and zooplankton using the remote sensing net primary productivity, biomass, temperature, and mixed layer depth. The ecosystem model and approach are validated for the GoM and used to assess error propagation. An eddy detection algorithm, tuned for the GoM, is used to calculate the phytoplankton and zooplankton biomass within eddy centers, around eddy edges, and in the immediate surroundings of the eddy to determine the impact of cyclonic and anticyclonic eddies and submesoscale edge effects on patterns of trophic transfer variability. Cyclonic eddy centers increase biomass and anticyclonic eddy centers decrease biomass in the oligotrophic GoM. Eddy edges contribute to variability in biomass but to a lesser extent than eddy centers. Zooplankton grazing varies in a similar pattern as biomass, and in this oligotrophic region, most grazing is on the largest size class of prey available. Nutrient injection stimulated by eddy dynamics more strongly projects onto biomass in zooplankton trophic levels and their associated grazing which suggests many eddies in the oligotrophic GoM experience top-down control. An understanding of mesoscale eddy impacts on zooplankton dynamics may explain variations in larval fish growth. Advances in remote sensing that allow the discrimination of phytoplankton functional types, such as the new PACE satellite, will be useful for providing a more complete base of the food web and thus enhance estimation of zooplankton biomass.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 INTEGRATING BIOTELEMETRY AND HYDROACOUSTIC DATA TO ESTIMATE THE ABUNDANCE OF THE FALL SPAWNING RUN OF ATLANTIC STURGEON IN THE MARSHYHOPE CREEK-NANTICOKE RIVER SYSTEM(2022) Coleman, Nicholas; Secor, Dr. David H; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Once thought to be extirpated, fall spawning runs of Atlantic sturgeon (Acipenser oxyrinchus) have been rediscovered in the Nanticoke River-Marshyhope Creek system in Maryland and are currently listed as an endangered species within the Chesapeake Distinct Population Segment. Previously tagged adults predominate survey captures, suggesting a very small population size. A key challenge is to estimate abundance for such a small population distributed between presumed spawning reaches of the connected Nanticoke River and Marshyhope Creek. This study leverages data collected from a dense telemetry receiver array and multiple side-scan sonar surveys conducted from August to October to estimate reach specific and superpopulation abundances in 2020 and 2021. I modified an approach that integrates mobile hydroacoustic data with biotelemetry, here applying for stationary telemetry receiver data. In 2020 and 2021, I estimated that 36 (95% confidence interval: 25-55) and 74 (95% confidence interval: 52-109) sturgeon used the Nanticoke River-Marshyhope Creek system, respectively. The higher estimate in 2021 coincided with higher sonar count data and low and stable river flows and temperature. Still, this large difference has no clear cause. Overall, run estimates support previous hypotheses that the Nanticoke system supports a very small population and that both the Marshyhope Creek and upper Nanticoke River serve as important areas for spawning activity. Going forward, enhanced sampling of the Upper Nanticoke River and targeted analysis assessing the relationship between phenology and environmental conditions would further develop our understanding of interannual changes in spawning run abundance.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 Marsh-ing Through Time: Resolving the temporal and spatial variability of tidal marsh sediment dissolved organic carbon sorption(2021) Morrissette, Hannah; Hood, Raleigh; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Tidal marsh ecosystems are among the most economically and ecologically valuable environments in the world, providing critical ecosystem services and a continuous exchange of carbon between these systems and their surrounding environments. Tidal marshes are an important overall net carbon sink, while simultaneously being a substantial source of dissolved organic carbon (DOC) to estuaries and the coastal ocean. The temporal and spatial variability in these carbon fluxes is large, difficult to measure, and currently considered to be one of the most daunting challenges to carbon exchange quantification. Sorption, despite being known as a dominant DOC exchange process at the sediment-water interface, is still understudied in tidal marsh ecosystems, with exchange kinetics largely unquantified. This research combined observational data with sediment flux modeling to answer a suite of questions addressing sorption speed, its variability, and its impacts to DOC fluxes between sediments and adjacent waters. Sediment flux models must incorporate sorption processes to more accurately simulate DOC fluxes between tidal marsh sediments and adjacent waters. Kinetics of these processes were quantified for the first time through a set of 24 hour sorption laboratory experiments, from which results showed that the majority of sorption processes occur rapidly, within 15 minutes of sediment exposure to water. Sorption rate parameters were determined through a numerical modeling study that simulated the laboratory experiments. These rates were used to parameterize a sediment flux model that included sorption processes formulated with varying degrees of complexity. The sorption kinetics of individual pools of DOC (colored and non-colored) were also measured, revealing that these separate pools sorb quickly but independently of one another, with preferential adsorption of humic colored DOC over time, and preferential desorption of native non-colored DOC over time. Sorption kinetics were also shown to be spatially variable within a marsh site, with adsorption decreasing with sediment depth and distance from the creek edge. This research provided important new information on sorption in tidal marsh sediments that allows these processes to be incorporated into models, which will, ultimately, facilitate efforts to simulate and quantify coastal carbon fluxes.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 Evaluating Substrate Rehabilitation Techniques for Bottom Culture of the Eastern Oyster (Crassostrea virginica) in Chesapeake Bay(2020) Long, Jessie Todd; Cornwell, Jeffrey C; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The degradation of Chesapeake Bay bottom conditions and oyster beds over the past century from habitat destruction, overharvesting, disease, and sedimentation have resulted in many areas that are detrimental for healthy oyster populations. In leased oyster aquaculture areas, unsuitable bottom characteristics result in suboptimal survival. Although the addition of oyster shell as substrate has been a common practice for building new oyster beds, the current high cost and lack of available shell can make this approach impractical. The goal of this study was to measure the effects of new and traditional bottom rehabilitation techniques (harrowing and shell addition) on oyster survival and growth on three distinct bottom types. The data revealed that treatments, whether singularly or in combination, were insignificant in respect to oyster size and survival across all bottom types. However, the observed bottom type had a significant effect on the percentage of oyster survival.Item Co-producing Environmental Knowledge with Community Stakeholders(2020) Todd-Rodriguez, Alana; Paolisso, Michael J; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)To generate robust and integrated solutions to complex sustainability problems requires the co-production of environmental knowledge. Co-production focuses on the socio-ecological contexts and knowledge forms of diverse actors in iterative dialogue to collectively generate new knowledge and practices relevant to societal challenges and decision-making. Despite its growing popularity, there remain a range of challenges and structural barriers obstructing the inclusion of local communities and place-based knowledge in co-producing environmental research and management. This thesis presents results from a comprehensive review of the co-production literature in general and focuses in particular on case studies where local environmental knowledge and stakeholders are included within the co-production process. Key findings suggest that additional attention to institutional capacity constraints, such as socio-political processes, space, funding, timing, and facilitation, as well as power and inclusion constraints, such as representation and knowledge, provide opportunities for increased integration of local environmental knowledge in the co-production process.Item EFFECTS OF ASSESSMENT FREQUENCY AND DATA-MANAGEMENT LAG ON FISHERY MANAGMEMENT PERFORMANCE: STRATEGIES FOR IMPROVEMENT(2015) Sylvia, Andrea Lynn; Wilberg, Michael J; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Some challenges of using stock assessments in management decisions are data availability and the allocation of resources to conduct stock assessments in a frequent and timely manner. We conducted a simulation evaluation that included the population dynamics, stock assessment, and management. Our objectives were to 1) determine effects of assessment interval and data-management lag and 2) test methods to reduce data lag by using partial data in the last year of the assessment. We found that increasing assessment interval and data-management lag caused a decrease in average catch and biomass across scenarios, with data-management lag having a larger effect compared to assessment interval. To reduce the effects of data-management lag, lag reduction methods that included some information about the age-composition of the catch and survey performed about as well as not having lag. Stock assessment interval, data-management lag and lag reduction methods should be considered when designing fishery management plans.Item DEVELOPMENT, VALIDATION, AND APPLICATION OF A QUANTITATIVE POLYMERASE CHAIN REACTION ASSAY TO ASSESS HEMATODINIUM PEREZI PREVALENCE IN ENVIRONMENTAL SAMPLES(2012) Hanif, Ammar; Schott, Eric J; Jagus, Rosemary; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Dinoflagellate parasites in the Hematodinium genus have emerged as important pathogens of economically important crustaceans worldwide, causing significant economic losses to fisheries and aquaculture. An understanding of the routes of infection in blue crab (Callinectes sapidus) populations would be facilitated by an improved knowledge of environmental reservoirs. A previously used PCR assay, based on small subunit rRNA sequences, lacked the specificity needed for Hematodinium perezi detection of environmental samples. Therefore a quantitative PCR assay based on the internal transcribed spacer 2 (ITS2) region of H. perezi rRNA genes was developed, validated, and applied to examine temporal and spatial incidences of environmental reservoirs in Delmarva coastal bays. H. perezi was detected in sediment and water in several Delmarva coastal bays, as well as the host, C. sapidus. Results suggest the existence of localized sediment reservoirs in areas where hydrological and geophysical features allow for the formation of cell deposits.