@article {Bourque2017,
	title = {{Macrofaunal communities associated with chemosynthetic habitats from the U.S. Atlantic margin: A comparison among depth and habitat types}},
	journal = {Deep Sea Research Part II: Topical Studies in Oceanography},
	volume = {137},
	year = {2017},
	pages = {42{\textendash}55},
	abstract = {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{\textendash}412 m) and a deep site near Norfolk Canyon (NCS, 1467{\textendash}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 ({\textgreater}300 $μ$m) in mussel beds, mats, and slope habitats at both sites. Community data from the deep site were also assessed in relation to the associated sediment environment (organic carbon and nitrogen, stable carbon and nitrogen isotopes, grain size, and depth). Infaunal assemblages and densities differed both between depths and among habitat types. Macrofaunal densities in microbial mats were four times greater than those present in mussel beds and slope sediments and were dominated by the annelid families Dorvilleidae, Capitellidae, and Tubificidae, while mussel habitats had higher proportions of crustaceans. Diversity was lower in BCS microbial mat habitats, but higher in mussel and slope sediments compared to NCS habitats. Multivariate statistical analysis revealed specific sediment properties as important for distinguishing the macrofaunal communities, including larger grain sizes present within NCS microbial mat habitats and depleted stable carbon isotopes ($δ$13C) in sediments present at mussel beds. These results suggest that habitat differences in the quality and source of organic matter are driving the observed patterns in the infaunal assemblages, including high $\beta$ diversity and high variability in the macrofaunal community composition. This study is the first investigation of seep infauna along the U.S. Atlantic slope north of the Blake Ridge Diapir and provides a baseline for future regional comparisons to other seep habitats along the Atlantic margin.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.dsr2.2016.04.012},
	author = {Bourque, J R and Robertson, C M and Brooke, S and Demopoulos, A W J}
}
@article {Prouty2016a,
	title = {{Growth rates and ages of deep-sea corals impacted by the Deepwater Horizon oil spill}},
	journal = {Deep Sea Research Part II: Topical Studies in Oceanography},
	volume = {129},
	year = {2016},
	pages = {196{\textendash}212},
	abstract = {The impact of the April 2010 Deepwater Horizon (DWH) spill on deep-sea coral communities in the Gulf of Mexico (GoM) is still under investigation, as is the potential for these communities to recover. Impacts from the spill include observation of corals covered with flocculent material, with bare skeleton, excessive mucous production, sloughing tissue, and subsequent colonization of damaged areas by hydrozoans. Information on growth rates and life spans of deep-sea corals is important for understanding the vulnerability of these ecosystems to both natural and anthropogenic perturbations, as well as the likely duration of any observed adverse impacts. We report radiocarbon ages and radial and linear growth rates based on octocorals (Paramuricea spp. and Chrysogorgia sp.) collected in 2010 and 2011 from areas of the DWH impact. The oldest coral radiocarbon ages were measured on specimens collected 11 km to the SW of the oil spill from the Mississippi Canyon (MC) 344 site: 599 and 55 cal yr BP, suggesting continuous life spans of over 600 years for Paramuricea biscaya, the dominant coral species in the region. Calculated radial growth rates, between 0.34 $μ$m yr-1 and 14.20 $μ$m yr-1, are consistent with previously reported proteinaceous corals from the GoM. Anomalously low radiocarbon ($Δ$14C) values for soft tissue from some corals indicate that these corals were feeding on particulate organic carbon derived from an admixture of modern surface carbon and a low 14C carbon source. Results from this work indicate fossil carbon could contribute 5{\textendash}10{\%} to the coral soft tissue $Δ$14C signal within the area of the spill impact. The influence of a low 14C carbon source (e.g., petro-carbon) on the particulate organic carbon pool was observed at all sites within 30 km of the spill site, with the exception of MC118, which may have been outside of the dominant northeast{\textendash}southwest zone of impact. The quantitatively assessed extreme longevity and slow growth rates documented here highlight the vulnerability of these long-lived deep sea coral species to disturbance.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.dsr2.2014.10.021},
	author = {Prouty, N G and Fisher, C R and Demopoulos, A W J and Druffel, E R M}
}
@article {Prouty2016,
	title = {{Insights into methane dynamics from analysis of authigenic carbonates and chemosynthetic mussels at newly-discovered Atlantic Margin seeps}},
	journal = {Earth and Planetary Science Letters},
	volume = {449},
	year = {2016},
	pages = {332{\textendash}344},
	abstract = {The recent discovery of active methane venting along the US northern and mid-Atlantic margin represents a new source of global methane not previously accounted for in carbon budgets from this region. However, uncertainty remains as to the origin and history of methane seepage along this tectonically inactive passive margin. Here we present the first isotopic analyses of authigenic carbonates and methanotrophic deep-sea mussels, Bathymodiolus sp., and the first direct constraints on the timing of past methane emission, based on samples collected at the upper slope Baltimore Canyon (\~{}385 m water depth) and deepwater Norfolk (\~{}1600 m) seep fields within the area of newly-discovered venting. The authigenic carbonates at both sites were dominated by aragonite, with an average View the MathML source$δ$C13 signature of -47{\textperthousand}-47{\textperthousand}, a value consistent with microbially driven anaerobic oxidation of methane-rich fluids occurring at or near the sediment{\textendash}water interface. Authigenic carbonate U and Sr isotope data further support the inference of carbonate precipitation from seawater-derived fluids rather than from formation fluids from deep aquifers. Carbonate stable and radiocarbon (View the MathML source$δ$C13 and View the MathML source$Δ$C13) isotope values from living Bathymodiolus sp. specimens are lighter than those of seawater dissolved inorganic carbon, highlighting the influence of fossil carbon from methane on carbonate precipitation. U{\textendash}Th dates on authigenic carbonates suggest seepage at Baltimore Canyon between 14.7{\textpm}0.6 ka14.7{\textpm}0.6 ka to 15.7{\textpm}1.6 ka15.7{\textpm}1.6 ka, and at the Norfolk seep field between 1.0{\textpm}0.7 ka1.0{\textpm}0.7 ka to 3.3{\textpm}1.3 ka3.3{\textpm}1.3 ka, providing constraint on the longevity of methane efflux at these sites. The age of the brecciated authigenic carbonates and the occurrence of pockmarks at the Baltimore Canyon upper slope could suggest a link between sediment delivery during Pleistocene sea-level lowstand, accumulation of pore fluid overpressure from sediment compaction, and release of overpressure through subsequent venting. Calculations show that the Baltimore Canyon site probably has not been within the gas hydrate stability zone (GHSZ) in the past 20 ka, meaning that in-situ release of methane from dissociating gas hydrate cannot be sustaining the seep. We cannot rule out updip migration of methane from dissociation of gas hydrate that occurs farther down the slope as a source of the venting at Baltimore Canyon, but consider that the history of rapid sediment accumulation and overpressure may play a more important role in methane emissions at this site.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.epsl.2016.05.023},
	author = {Prouty, N G and Sahy, D and Ruppel, C D and Roark, E B and Condon, D and Brooke, S and Ross, S W and Demopoulos, A W J}
}
@article {Demopoulos2014,
	title = {{Biodiversity and community composition of sediment macrofauna associated with deep-sea Lophelia pertusa habitats in the Gulf of Mexico}},
	journal = {Deep-Sea Research. Part I: Oceanographic Research Papers},
	volume = {93},
	year = {2014},
	pages = {91{\textendash}103},
	abstract = {Scleractinian corals create three-dimensional reefs that provide sheltered refuges, facilitate sediment accumulation, and enhance colonization of encrusting fauna. While heterogeneous coral habitats can harbor high levels of biodiversity, their effect on the community composition within nearby sediments remains unclear, particularly in the deep sea. Sediment macrofauna from deep-sea coral habitats (Lophelia pertusa) and non-coral, background sediments were examined at three sites in the northern Gulf of Mexico (VK826, VK906, MC751, 350{\textendash}500 m depth) to determine whether macrofaunal abundance, diversity, and community composition near corals differed from background soft-sediments. Macrofaunal densities ranged from 26 to 125 individuals 32 cm-2 and were significantly greater near coral versus background sediments only at VK826. Of the 86 benthic invertebrate taxa identified, 16 were exclusive to near-coral habitats, while 14 were found only in background sediments. Diversity (Fisher{\textquoteright}s $\alpha$) and evenness were significantly higher within near-coral sediments only at MC751 while taxon richness was similar among all habitats. Community composition was significantly different both between near-coral and background sediments and among the three primary sites. Polychaetes numerically dominated all samples, accounting for up to 70{\%} of the total individuals near coral, whereas peracarid crustaceans were proportionally more abundant in background sediments (18{\%}) than in those near coral (10{\%}). The reef effect differed among sites, with community patterns potentially influenced by the size of reef habitat. Taxon turnover occurred with distance from the reef, suggesting that reef extent may represent an important factor in structuring sediment communities near L. pertusa. Polychaete communities in both habitats differed from other Gulf of Mexico (GOM) soft sediments based on data from previous studies, and we hypothesize that local environmental conditions found near L. pertusa may influence the macrofaunal community structure beyond the edges of the reef. This study represents the first assessment of L. pertusa-associated sediment communities in the GOM and provides baseline data that can help define the role of transition zones, from deep reefs to soft sediments, in shaping macrofaunal community structure and maintaining biodiversity; this information can help guide future conservation and management activities.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.dsr.2014.07.014},
	author = {Demopoulos, A W J and Bourque, J R and Frometa, J}
}
@article {White2012,
	title = {{Impact of the Deepwater Horizon oil spill on a deep-water coral community in the Gulf of Mexico}},
	journal = {Proceedings of the National Academy of Sciences of the United States of America},
	volume = {109},
	number = {50},
	year = {2012},
	month = {dec},
	pages = {20303{\textendash}20308},
	abstract = {To assess the potential impact of the Deepwater Horizon oil spill on offshore ecosystems, 11 sites hosting deep-water coral communities were examined 3 to 4 mo after the well was capped. Healthy coral communities were observed at all sites {\textgreater}20 km from the Macondo well, including seven sites previously visited in September 2009, where the corals and communities appeared unchanged. However, at one site 11 km southwest of the Macondo well, coral colonies presented widespread signs of stress, including varying degrees of tissue loss, sclerite enlargement, excess mucous production, bleached commensal ophiuroids, and covering by brown flocculent material (floc). On the basis of these criteria the level of impact to individual colonies was ranked from 0 (least impact) to 4 (greatest impact). Of the 43 corals imaged at that site, 46{\%} exhibited evidence of impact on more than half of the colony, whereas nearly a quarter of all of the corals showed impact to {\textgreater}90{\%} of the colony. Additionally, 53{\%} of these corals{\textquoteright} ophiuroid associates displayed abnormal color and/or attachment posture. Analysis of hopanoid petroleum biomarkers isolated from the floc provides strong evidence that this material contained oil from the Macondo well. The presence of recently damaged and deceased corals beneath the path of a previously documented plume emanating from the Macondo well provides compelling evidence that the oil impacted deep-water ecosystems. Our findings underscore the unprecedented nature of the spill in terms of its magnitude, release at depth, and impact to deep-water ecosystems.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {0027-8424},
	doi = {10.1073/pnas.1118029109},
	author = {White, H K and Hsing, P-Y and Cho, W and Shank, T M and Cordes, E E and Quattrini, A M and Nelson, R K and Camilli, R and Demopoulos, A W J and German, C R and Brooks, J M and Roberts, H H and Shedd, W and Reddy, C M and Fisher, C R}
}
