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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    Light available to the seagrass Zostera marina when exposed to currents and waves
    (2009) McKone, Katie Lynn; Koch, Evamaria W; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Aquatic organisms are regularly exposed to varying degrees of hydrodynamic forces such as currents and waves. Seagrasses, which are rooted in the sediment, have flexible leaves, allowing them to sway back and forth with waves and deflect with currents. Furthermore, seagrasses can acclimate to local hydrodynamic forces exerted upon them by changing their morphology, which may benefit the organism via reduced drag, but may also bring disadvantages such as increased self-shading. We examined the interaction between water flow and morphology of the seagrass Zostera marina, and how this interaction affects light availability to the plant. We also assessed carbon and nutrient content of Z. marina, as the uptake of these constituents has been linked to hydrodynamic conditions and sediment composition. Our results indicate that local hydrodynamics and sediment composition induce morphological variation in the seagrass Z. marina, and that this variation influences light availability to the seagrass canopy.
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    Acclimation of marine macrophytes (Saccharina latissima and Zostera marina) to water flow
    (2008-05-12) Jordan, Terry Lynn; Koch, Evamaria; Davison, Ian; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    I examined the physiological response of two marine macrophytes, the brown alga Saccharina latissima and the angiosperm Zostera marina, to water flow in nature and in controlled experiments. Limitation of photosynthesis of both species by the availability of dissolved inorganic carbon (DIC) was increased under low current velocities. Physiological acclimation to low water flow occurred via upregulation of DIC uptake mechanisms in both S. latissima and Z. marina. Both species increased their ability to generate CO2 in the boundary layer by increasing external carbonic anhydrase and in Z. marina by also increasing proton extrusion and photosynthetic capacity. Changes in the xanthophyll-cycle in low-flow grown S. latissima increased non-photochemical quenching, thus reducing photodamage when photosynthesis was limited by DIC uptake. Water flow also affected root length in Z. marina but root length and below ground biomass were also significantly affected by sediment type, an indirect effect of water flow.