کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4532228 1626153 2013 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Interannual changes in seafloor surficial geology at an artificial reef site on the inner continental shelf
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
پیش نمایش صفحه اول مقاله
Interannual changes in seafloor surficial geology at an artificial reef site on the inner continental shelf
چکیده انگلیسی


• Scour around groups of objects results in coarsening of surface sediments.
• Underlying geology affects the extent of object settling.
• Seasonal subtropical storms are responsible for scour.
• Reefed subway cars reach stasis with the environment 6–7 years after placement.
• Object orientation and clustering influences spatial extent of scour.

The influence of reef structures on seafloor surface sediments has implications for marine spatial planning and coastal development, including use of the coastal zone for offshore wind energy. We present results of interannual changes in seafloor surficial geology at the Redbird artificial reef site, located on the continental shelf offshore of Delaware Bay. The Redbird reef is composed of NYC subway cars, barges, tugboats, and other sunken objects. Since objects were added sporadically between 1996 and 2009, the survey area acts as a natural laboratory to study the evolution of the surrounding seafloor at a structural reef habitat through time. Annual side-scan surveys from 2008 through 2011, and one bathymetric survey in 2010 provide information about surface geology and morphology. Local wave and current data for this time period were analyzed to determine the main morphological agents. Automated backscatter segmentation show that three bottom types dominate and that these large-scale (>10 m) surface sediment patterns persist from year to year. Grab samples reveal that the bottom types are silty sand with clay and sandy gravel. Clear sediment and biological patterns emerged revealing the influence of the objects on the seafloor. Comet-shaped moats of sandy gravel surround single objects and grow to form large-scale coalesced patches around groups of objects. Alignment of sediment patches suggests the periodic hydrodynamic influence of seasonal storms. The abundance and diversity of organisms increases with decreasing clay/silt content. Evidence of scour includes the removal of fine sediments, the formation of moats 1–30 m in diameter and 0.5–1 m deep around the reef objects, and the >1 m settling of objects into the seafloor. Data suggest subway cars reached equilibrium with the environment in 6–7 years, but that larger objects or clusters of objects take a longer time to equilibrate and have farther-reaching effects. Knowledge of local wave and current climate and stratigraphy could inform decisions of object clustering and orientation to decrease scour impacts.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Continental Shelf Research - Volume 58, 15 April 2013, Pages 67–78
نویسندگان
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