Browsing by Author "Trembanis, Arthur C."
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Item Assessing the use of a camera system within an autonomous underwater vehicle for monitoring the distribution and density of sea scallops (Placopecten magellanicus) in the Mid-Atlantic Bight(National Marine Fisheries Service., 2016-04-26) Walker, Justin H.; Trembanis, Arthur C.; Miller, Douglas C.; Justin H. Walker, Arthur C. Trembanis and Douglas C. Miller; Walker, Justin H.; Trembanis, Arthur C.; Miller, Douglas C.The sea scallop (Placopecten magellanicus) fishery in the Atlantic is assessed during annual surveys by using both dredging and surface-deployed imaging techniques. In this pilot study in the Mid-Atlantic Bight, we used an autonomous underwater vehicle (AUV) to photograph the seafloor and to evaluate its use for determining scallop density and size. During 22 surveys in 2011, 257 km of seafloor were photographed, resulting in over 203,000 color images. Using trained annotators and photogrammetric software, we determined scallop density and shell heights for 15,252 scallops. The inshore scallop grounds near Long Island (at depths <40 m) had a density of 0.077 scallops per m2, whereas the inshore grounds of the New York Bight had a density of 0.012 scallops per m2. Shell heights derived from images were found to agree well with measurements from scallops collected with a commercial dredge. We show that images obtained with an AUV can be used to reliably estimate both density and shell height consistent with direct sampling from the same area. Moreover, side-scan sonar images obtained with an AUV can be used to detect dredge scars and, therefore, can provide a simultaneous, relative estimate of fishing effort in that area. AUVs provide a highly accurate suite of data for each survey site and therefore allow the design of experimental studies of fishing practices.Item Hydrodynamics and Sediment-Transport Pathways along a Mixed-Energy Spit-Inlet System: A Modeling Study at Chincoteague Inlet (Virginia, USA)(Journal of Marine Science and Engineering, 2023-05-18) Georgiou, Ioannis Y.; Messina, Francesca; Sakib, Md Mohiuddin; Zou, Shan; Foster-Martinez, Madeline; Bregman, Martijn; Hein, Christopher J.; Fenster, Michael S.; Shawler, Justin L.; McPherran, Kaitlyn; Trembanis, Arthur C.Tidal-inlet systems are dynamic features that respond to short-term (e.g., storms) and longer-term processes (e.g., sea-level rise, changes in tidal prism). The Chincoteague Inlet system, located along the northern Eastern Shore of Virginia (USA), is a dynamic coastal complex that experiences rapid change associated with sediment redistribution and a shifting inlet throat due to the southern elongation of adjacent Assateague Island. In this study, a numerical model based on Delft3D with coupled flow–waves, multiclass sediment transport, and morphologic feedback was developed to quantify the hydrodynamic and geomorphic controls within this rapidly evolving inlet–spit system and to develop a more comprehensive understanding of regional to local controls on sediment-transport pathways. Model results show that most of the sand transport along southern Assateague Island is sequestered nearshore and proximally in deeper sinks within Fishing Point, and, of that, only finer sand sizes are transported around the spit, confirming previous analysis and hypothesis. The model also showed that sand transport toward the south increases along Wallops Island and quantified spatially explicit transport trends for selected sediment classes, revealing that coarser sediment bypassing is a punctuated process that is proportional to storms.