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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    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.
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    Zooplankton Population Dynamics in Relation to the Red Tide Dinoflagellate Karenia brevis on the West Florida Shelf of the Gulf of Mexico
    (2012) Walsh, Brianne Marie; O'Neil, Judith M; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Blooms of the toxin producing dinoflagellate Karenia brevis are common in the Gulf of Mexico, and while several studies have investigated nutrient sources and bloom processes, there has been less research in regards to zooplankton population dynamics within these blooms. Zooplankton community structure and copepod species composition were analyzed from samples collected on the West Florida Shelf during October 2007-2010. Copepods constituted the most important zooplankton group, averaging 60% of total abundance. In 2009 there was a significant difference between the abundance of zooplankton at stations within a K. brevis bloom. As the K. brevis bloom progressed, total zooplankton abundance decreased. Additionally, the role of zooplankton within Karenia brevis blooms was investigated as both grazers of primary productivity and potential sources of regenerated nutrients.