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Craig M. Robertson

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Hydrocarbon seeps support distinct benthic communities capable of tolerating extreme environmental conditions and utilizing reduced chemical compounds for nutrition. In recent years, several locations of methane seepage have been mapped along the U.S. Atlantic continental slope. In 2012 and 2013, two newly discovered seeps were investigated in this region: a shallow site near Baltimore Canyon (BCS, 366–412 m) and a deep site near Norfolk Canyon (NCS, 1467–1602 m), with both sites containing extensive chemosynthetic mussel bed and microbial mat habitats. Sediment push cores, suction samples, and Ekman box cores were collected to quantify the abundance, diversity, and community structure of benthic macrofauna (>300...
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Submarine canyons are often hotspots of biomass and productivity in the deep sea. However, the majority of deep-sea canyons remain poorly sampled. Using a multi-tracer approach, results from a detailed geochemical investigation from a year-long sediment trap deployment reveals details concerning the source, transport, and fate of particulate matter to the depositional zone (1318 m) of Baltimore Canyon on the US Mid-Atlantic Bight (MAB). Both organic biomarker composition (sterol and n-alkanes) and bulk characteristics (δ13C, Δ14C, Chl-a) suggest that on an annual basis particulate matter from marine and terrestrially-derived organic matter are equally important. However, elevated Chlorophyll-a and sterol concentrations...
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Submarine canyons are morphologically complex systems, acting as major conduits of organic matter along continental shelves, promoting gradients in food resources, habitat heterogeneity, and areas of sediment resuspension and deposition. Often environmental conditions within canyons can be highly distinct, particularly in different parts of the canyon and in contrast to adjacent slopes. Here we examine how biogeochemical drivers shape the differences between canyon and slope infaunal communities in Baltimore and Norfolk Canyons in the U.S. Mid-Atlantic Region. Specific comparisons included macrofaunal communities in Norfolk canyons and adjacent slope, hard substrate associated macrofaunal communities in Norfolk...
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