Biology

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Subject: search.filters.subject.Marine geology

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    Evaluating feedbacks between vegetation and sediment dynamics in Submersed Aquatic Vegetation (SAV) beds and created marshes of living shorelines in Chesapeake Bay
    (2020) Bolton, Miles Charles; Palinkas, Cindy M; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Intertidal marshes and subtidal submersed aquatic vegetation (SAV) provide similar ecosystem services such as wave attenuation, provision of nursery habitat, water filtration, and sediment and nutrient retention. They are often found together in the coastal zone, especially when marshes have been created for shoreline protection in living shorelines. This study examines sediment dynamics within the created marshes of living shorelines and adjacent nearshore SAV habitat in mesohaline Chesapeake Bay, and within emergent, patchy SAV beds of the Susquehanna Flats. The naturally occurring radioisotopes 7Be (half-life: 53.3 days) and 210Pb (half-life: 22.3 years) were used to calculate seasonal- and decadal-scale sedimentation rates. Mud content, organic content, and nutrient concentrations were analyzed to describe sedimentary characteristics. Coastal habitats in the Chesapeake Bay exert significant influence on local sediment dynamics, further research on feedbacks between coastal vegetation and sediment dynamics can improve our understanding on how coastal ecosystems interact with Bay-wide shifts in sediment dynamics.
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    Spatial and Temporal Variability in Suspended Sediment Characteristics in the Surface Layer of the Upper Chesapeake Bay
    (2020) Barletta, Stephanie Marie; Sanford, Lawrence P; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Periodic high discharge events flush suspended sediments from the Susquehanna River and Conowingo Dam reservoir into the upper Chesapeake Bay, which extends from the mouth of the Susquehanna River to the Bay Bridge near Annapolis, MD. Sediment characteristics in the surface layer of the upper Bay and changes in these characteristics with varying river discharge and distance downstream are not well known. In order to develop an integrated understanding of surface layer sediment dynamics, several in-situ data sets were examined at the Bay head and downstream along the Bay’s center channel, providing data on the spatial and temporal variability of suspended particle characteristics including concentration, settling speed, bulk density, and size. It was found that particles are entirely disaggregated at the Dam, later aggregating to a limited extent down Bay, and that downstream characteristics are more weakly linked to Susquehanna flow at lower flows and longer distances.
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    Water Flow and Sediment Texture as Co-Varying Submersed Aquatic Vegetation (SAV) Habitat Requirements
    (2013) Swerida, Rebecca M.; Koch, Evamaria W; Sanford, Lawrence P; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This study examined the importance of water flow and sediment texture as co-varying habitat parameters of submerged aquatic vegetation (SAV) in the Chesapeake Bay. An outdoor mesocosm experiment was conducted to test the response of SAV (Zostera marina and Ruppia maritima) to combinations of water flows and sediment grain sizes characterized by sediment deposition, bedload transport and erosion. Water flow, sediment and SAV characteristics were also determined at vegetated and adjacent unvegetated areas at 11 study sites and sediment motion conditions assessed. Greater SAV biomass was developed by Z. marina and R. maritima experiencing sediment motion than sediment deposition. Although habitat parameter thresholds in situ were site-specific, overall SAV presence was limited to moderate ranges of both water flow and sediment grain size. All SAV habitat observed was characterized by sediment bedload transport. Consideration of both water flow and sediment habitat requirements will improve SAV restoration success.