@article {Johansen2017,
	title = {{Time series video analysis of bubble release processes at natural hydrocarbon seeps in the Northern Gulf of Mexico}},
	journal = {Marine and Petroleum Geology},
	volume = {82},
	year = {2017},
	pages = {21{\textendash}34},
	abstract = {This research quantifies the rate and volume of oil and gas released from two natural seep sites in the Gulf of Mexico: lease blocks GC600 (1200 m depth) and MC118 (850 m depth). Our objectives were to determine variability in release rates and bubble size at five individual vents and to investigate the effects of tidal fluctuations on bubble release. Observations with autonomous video cameras captured the formation of individual bubbles as they were released through partially exposed deposits of gas hydrate. Image processing techniques determined bubble type (oily, gaseous, and mixed: oily and gaseous), size distribution, release rate, and temporal variations (observation intervals ranged from 3 h to 26 d). A semi-automatic bubble counting algorithm was developed to analyze bubble count and release rates from video data. This method is suitable for discrete vents with small bubble streams commonly seen at seeps and is adaptable to multiple in situ set-ups. Two vents at GC600 (Birthday Candles 1 and Birthday Candles 2) were analyzed. They released oily bubbles with an average diameter of 5.0 mm at a rate of 4.7 bubbles s-1, and 1.3 bubbles s-1, respectively. Approximately 1 km away, within the GC600 seep site, two more vents (Mega Plume 1 and Mega Plume 2) were analyzed. These vents released a mixture of oily and gaseous bubbles with an average diameter of 3.9 mm at a rate of 49 bubbles s-1, and 81 bubbles s-1, respectively. The fifth vent at MC118 (Rudyville) released gaseous bubbles with an average diameter of 3.0 mm at a rate of 127 bubbles s-1. Pressure records at Mega Plume and Rudyville showed a diurnal tidal cycle (24.5 h). Rudyville was the only vent that demonstrated any positive correlation ($\rho$ = 0.60) to the 24.5 h diurnal tidal cycle. However, these observations were not conclusive regarding tidal effects on bubble release.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	doi = {10.1016/j.marpetgeo.2017.01.014},
	author = {Johansen, C and Todd, A C and MacDonald, I R}
}
@article {Peterson2013,
	title = {{On the utility of radium isotopes as tracers of hydrocarbon discharge}},
	journal = {Marine Chemistry},
	volume = {156},
	number = {SI},
	year = {2013},
	pages = {98{\textendash}107},
	abstract = {Natural seepage of hydrocarbons commonly occurs in the Gulf of Mexico and numerous other locations around the world{\textquoteright}s oceans. In-situ quantification of discharge and transport of these hydrocarbons through the water column is somewhat limited by a lack of available tracers. Here, we consider the utility of using radium isotopes, which are commonly enriched in formation fluids contained within hydrocarbon reservoirs, as tracers of hydrocarbons discharged into the deep ocean. During a cruise in November/December 2010 through the Gulf of Mexico, radium isotopes (224Ra and 226Ra) revealed anomalous concentrations in near-bottom samples associated with the presence of hydrocarbons at several sites where hydrocarbon seepage was known to occur and observed real-time via the human-occupied vehicle Alvin. These tracers also indicated the presence of near-bottom hydrocarbons in the vicinity of the Macondo wellhead where the Deepwater Horizon blowout occurred months earlier. These hydrocarbons are presumed to originate from nearby gas seeps later identified by water column sonar returns. The short half-life of 224Ra (3.66~days) suggests that anomalously high unsupported activities of this isotope must be derived from recent (days to weeks) discharge. Sampling at the sediment{\textendash}water interface confirmed that the source of the water column radium isotope anomalies is likely benthic sources. These results suggest that radium isotopes may serve as useful tracers of hydrocarbons in such an environment, and we outline steps required to quantify discharge rates and transport time scales with these tracers.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	doi = {10.1016/j.marchem.2013.02.008},
	author = {Peterson, R N and Viso, R F and MacDonald, I R and Joye, S B}
}
@article {Lessard-Pilon2010,
	title = {{Community composition and temporal change at deep Gulf of Mexico cold seeps}},
	journal = {Deep-Sea Research. Part II: Topical Studies in Oceanography},
	volume = {57},
	number = {21-23},
	year = {2010},
	pages = {1891{\textendash}1903},
	abstract = {Specialized cold-seep communities have been known to exist in the Gulf of Mexico (GOM) since the mid-1980s, but only recently has extensive research been carried out on sites at depths {\textgreater}1000 m. This study uses a combination of imagery and analyses within a Geographic Information Systems (GIS) framework to examine the composition of mussel and tubeworm communities at depths between 2200 and 2800 m in the Gulf of Mexico, spatial relations among the fauna, and changes in these communities over time. Photomosaics at three discrete seep communities were obtained in 2006 and a video mosaic of another community was obtained in 1992. Each of these communities was re-imaged in 2007. In addition, quantitative physical collections were made within two of the photomosaic sites and used to confirm the identification of megafauna, quantify the occurrence of smaller and cryptic macrofauna, and allow first-order calculations of biomass within the sites. Substrate type had a significant effect on community composition. Significant associations were identified between live mussels with anemones, shrimp, and sea cucumbers, and between tubeworm aggregations and Munidopsis sp. crabs and encrusting fauna, indicating differences in the composition of megafauna associated with adjacent mussel and tubeworm aggregations. Little change was seen in the total area colonized by foundation fauna (tubeworms and mussels) between years at any site. However, significant changes occurred in the positions of mussels, even over periods of a single year, at all sites, and evidence for the establishment of new tubeworm aggregations between 1992 and 2007 was noted at one site. These photomosaics provide data suggesting that environmental conditions can change over small spatial and temporal scales and mussels move in response to these changes. The successional trends are examined and compared to the patterns that have been documented in shallow ({\textless}1000-m depth) Gulf of Mexico seep communities.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {0967-0645},
	doi = {10.1016/j.dsr2.2010.05.012},
	url = {http://dx.doi.org/10.1016/j.dsr2.2010.05.012},
	author = {Lessard-Pilon, S and Porter, M D and Cordes, E E and MacDonald, I R and Fisher, C R}
}
@article {Garcia-Pineda2010,
	title = {{Remote-sensing evaluation of geophysical anomaly sites in the outer continental slope, northern Gulf of Mexico}},
	journal = {Deep-Sea Research. Part II: Topical Studies in Oceanography},
	volume = {57},
	number = {21-23},
	year = {2010},
	pages = {1859{\textendash}1869},
	abstract = {Synthetic Aperture Radar (SAR) images obtained from satellites are a reliable tool for localizing natural hydrocarbon seeps. For this study, we used the Texture Classifier Neural Network Algorithm (TCNNA) to interpret SAR data from the RADARSAT satellite and a geostatistical clustering analysis to compare seeps detected in 579 SAR images covering the northern Gulf of Mexico (GOM). Geostatistical analysis results indicate that, in a typical active seep formation, oil vents would be found within a seep formation \~{}2.5 km in diameter. Repeated observations of slicks at a given seep formation indicate that advection of rising oil in the water column causes an offset from the vent depending on water depth. At 500 m, the radial offset is up to 1400 m; at 2000 m, it is up to 3270 m. Observations with submersibles showed that, in 100{\%} of the cases, the calculated seep formations that are matched with active oil seeps correspond to anomalies interpreted from surface amplitude maps and migration pathways in the seismic data. However, episodically, larger releases from persistent seeps occurred, and also some other seep formations showed intermittent releases. Our analysis indicates that active oil seeps detected with SAR represent a subset of the total array of geophysical features generated by hydrocarbon migration on the northern continental slope of the Gulf of Mexico.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {0967-0645},
	doi = {10.1016/j.dsr2.2010.05.005},
	url = {http://dx.doi.org/10.1016/j.dsr2.2010.05.005},
	author = {Garcia-Pineda, O and MacDonald, I R and Zimmer, B and Shedd, B and Roberts, H}
}
@book {Brooks2008,
	title = {{Investigations of chemosynthetic communities on the lower continental slope of the Gulf of Mexico: Interim Report 1}},
	series = {OCS Reports},
	year = {2008},
	pages = {332},
	publisher = {U.S. Department of the Interior, Minerals Management Service},
	organization = {U.S. Department of the Interior, Minerals Management Service},
	address = {New Orleans, LA},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	url = {http://www.gomr.mms.gov/PI/PDFImages/ESPIS/4/4320.pdf},
	author = {Brooks, J M and Fisher, C R and Roberts, H and Bernard, B and MacDonald, I R and Carney, R and Jove, S and Cordes, E E and Wolff, G A and Goehring, E}
}
@article {Urcuyo2007,
	title = {{Growth and longevity of the tubeworm Ridgeia piscesae in the variable diffuse flow habitats of the Juan de Fuca Ridge}},
	journal = {Marine Ecology Progress Series},
	volume = {344},
	year = {2007},
	pages = {143{\textendash}157},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0171-8630},
	doi = {10.3354/meps06710},
	url = {http://dx.doi.org/10.3354/meps06710},
	author = {Urcuyo, I A and Bergquist, D C and MacDonald, I R and VanHorn, M and Fisher, C R}
}
