Theses and Dissertations from UMD

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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 give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

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    RESPONSES OF THE COPEPOD ACARTIA TONSA TO HYPOXIA IN CHESAPEAKE BAY
    (2015) Barba, Allison Patricia; Roman, Michael R; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Chesapeake Bay experiences seasonal hypoxia each year and while studies have been done investigating how the copepod Acartia tonsa responds to hypoxia, few studies have focused on a comprehensive understanding of how its behavior and fitness are affected by low oxygen. The abundance, distribution, fitness and diel vertical migration patterns of A. tonsa were measured on series of six cruises in 2011 and 2012 in spring, summer and fall. I found that copepod abundance, distribution and vertical migration were significantly affected when hypoxic waters occurred below the pycnocline. I also found that males were less impacted by hypoxia than females, with a greater decrease in female abundance and vertical migration when there were hypoxic bottom waters.
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    Zooplankton ecology in the Chesapeake Bay estuarine turbidity maximum, with emphasis on the calanoid copepod Eurytemora affinis
    (2006-04-27) Lloyd, Scott Steven; Roman, Michael R; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The estuarine turbidity maximum (ETM) region of Chesapeake Bay, located near the limit of saltwater intrusion, is characterized by high total suspended solid (TSS) concentrations, high light attenuation, and high densities of zooplankton. Due to high light attenuation, primary production is generally low in ETMs, yet the Chesapeake Bay ETM region is often considered a 'hot spot' of zooplankton abundance within the Bay. The omnivorous copepod Eurytemora affinis is especially prevalent in the ETMs of Chesapeake Bay and its tributaries and in ETM regions worldwide. In order to determine the factors influencing 1) zooplankton distribution and abundance in the Chesapeake Bay ETM, 2) E. affinis reproduction in the Chesapeake Bay and Choptank River ETMs, and 3) zooplankton position maintenance, cruises in the Chesapeake Bay and Choptank River ETMs were conducted in 1996 and 2001-2003. Laboratory experiments examining the egg production cycle of E. affinis were also performed. The cruise results show that zooplankton taxa within the Chesapeake Bay ETM region tend to be distributed along a salinity gradient from up-estuary to down-estuary, with cladocerans being most common in low salinity/freshwater regions, E. affinis found in slightly higher salinities than cladocerans, and mysids and the copepod Acartia tonsa found in more mesohaline conditions. Eurytemora affinis appears to be contained in the ETM by freshwater limiting its up-estuary extent and biological interactions with A. tonsa and salinity tolerances limiting its down-estuary abundance. Grazing and egg production results indicate that E. affinis production is not food-limited in the ETM region and that this copepod's particle selection ability favors its success in the ETM over that of A. tonsa. Laboratory egg production experiments also suggest that the most accurate estimates of E. affinis egg production (and of all brooding copepods in general) are achieved by incorporating both a temperature-based estimate of interclutch duration (the time between successive clutches) with a temperature-based estimate of egg hatching time.