@article {Levin2017,
	title = {{Methane seepage effects on biodiversity and biological traits of macrofauna inhabiting authigenic carbonates}},
	journal = {Deep Sea Research Part II: Topical Studies in Oceanography},
	volume = {137},
	year = {2017},
	pages = {26{\textendash}41},
	abstract = {Authigenic carbonate rocks at methane seeps are recognized as hosting diverse and abundant invertebrate assemblages, with potential forcing from fluid seepage and hydrography. Mensurative studies of carbonate macrofauna ({\textgreater}0.3 mm) at Hydrate Ridge, OR revealed little effect of water depth and overlying oxygenation (at 600 m and 800 m) but a large influence of seepage activity on density, taxonomic composition, diversity, and biological traits (feeding, lifestyle, motility, size and calcification). Rocks exposed to active seepage had 3{\textendash}4{\texttimes} higher total macrofaunal densities than under inactive conditions. Assemblages exhibited higher species richness and reduced evenness (greater dominance) under active seepage than inactive conditions, but no difference in H' or rarefaction diversity. Actively seeping sites were characterized by errant (motile), bacterial grazing, small- and medium-sized, heavily calcified species, whereas inactive sites exhibited a greater diversity of feeding modes and more burrowers, sessile, large and lightly calcified species. Active rocks supported more exogonid (Syllidae), ampharetid, and cirratulid polychaetes, provannid snails, pyropeltid limpets, nemerteans, and sponges; whereas inactive rocks supported higher densities of ophiuroids, isopods, gammarid amphipods, hydroids, Typosyllis (Syllidae) and tanaids. Transplant experiments, in which rocks were transferred between active and inactive sites at Hydrate Ridge North (600 m), revealed that assemblages respond within 13 months to increase or cessation of seepage, taking on the feeding, size and calcification characteristics of the background fauna at the new site. Lifestyles and motility patterns shifted more slowly as the sessile, attached species did not track seepage as quickly. Provannid snails and pyropeltid limpets rapidly colonized rocks transplanted to active sites and disappeared when transplanted to inactive sites. Given the known variability of fluid fluxes and rapid community response, a mosaic of communities changing in space and time is hypothesized to generate the relatively high species diversity at methane seeps.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.dsr2.2016.05.021},
	author = {Levin, L A and Mendoza, G F and Grupe, B M}
}
@article {Burkett2016,
	title = {{Colonization of over a thousand Cibicidoides wuellerstorfi (foraminifera: Schwager, 1866) on artificial substrates in seep and adjacent off-seep locations in dysoxic, deep-sea environments}},
	journal = {Deep Sea Research Part I: Oceanographic Research Papers},
	volume = {117},
	year = {2016},
	pages = {39{\textendash}50},
	abstract = {After {\~{}}1 yr on the seafloor at water depths of {\~{}}700 m on Hydrate Ridge in the Pacific, eight colonization experiments composed primarily of a plastic mesh cube (from here on refered to as SEA3, for Seafloor Epibenthic Attachment Cubes) were colonized by 1076 Cibicidoides wuellerstorfi on {\~{}}1841 cm2 of experimental substrate. This species is typically considered an indicator of well-oxygenated conditions, and recruitment of such large numbers in bottom waters with low dissolved oxygen availability (0.24{\textendash}0.37 mL/L) indicate that this taxon may not be as limited by oxygen as previously thought. Clues about substrate preferences were evident from the distribution, or lack thereof, of individuals among plastic mesh, coated steel frame, wooden dowels and reflective tape. Abundance, individual size distributions within cage populations and isotopic biogeochemistry of living foraminifera colonizing experimental substrates were compared between active seep and adjacent off-seep experiment locations, revealing potential differences between these environments. Few studies have examined foraminiferal colonization of hard substrates in the deep-sea and to our knowledge no previous study has compared foraminiferal colonization of active seep and off-seep substrates from the same region. This study provides initial results of recruitment, colonization, geochemical and morphological aspects of the paleoceanographically significant species, C. wuellerstorfi, from dynamic deep-sea environments. Further experimental deployments of SEA3s will provide a means to assess relatively unknown ecologic dynamics of important foraminiferal deep-sea species.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.dsr.2016.08.011},
	author = {Burkett, A M and Rathburn, A E and Perez, Elena M and Levin, L A and Martin, J B}
}
@article {ISI:000350053000004,
	title = {{Phylogenetic placement of Cibicidoides wuellerstorfi (Schwager, 1866) from methane seeps and non-seep habitats on the Pacific margin}},
	journal = {GEOBIOLOGY},
	volume = {13},
	number = {1},
	year = {2015},
	month = {jan},
	pages = {44{\textendash}52},
	type = {Article},
	abstract = {Benthic foraminifera are among the most abundant groups found in deep-sea habitats, including methane seep environments. Unlike many groups, no endemic foraminiferal species have been reported from methane seeps, and to our knowledge, genetic data are currently sparse for Pacific deep-sea foraminifera. In an effort to understand the relationships between seep and non-seep populations of the deep-sea foraminifera Cibicidoides wuellerstorfi, a common paleo-indicator species, specimens from methane seeps in the Pacific were analyzed and compared to one another for genetic similarities of small subunit rDNA (SSU rDNA) sequences. Pacific Ocean C. wuellerstorfi were also compared to those collected from other localities around the world (based on 18S gene available on Genbank, e.g., Schweizer et al., 2009). Results from this study revealed that C. wuellerstorfi living in seeps near Costa Rica and Hydrate Ridge are genetically similar to one another at the species level. Individuals collected from the same location that display opposite coiling directions (dextral and sinstral) had no species level genetic differences. Comparisons of specimens with genetic information available from Genbank (SSU rDNA) showed that Pacific individuals, collected for this study, are genetically similar to those previously analyzed from the North Atlantic and Antarctic. These observations provide strong evidence for the true cosmopolitan nature of C. wuellerstorfi and highlight the importance of understanding how these microscopic organisms are able to maintain sufficient genetic exchange to remain within the same species between seep and non-seep habitats and over global distances.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {1472-4677},
	doi = {10.1111/gbi.12118},
	author = {Burkett, A M and Rathburn, A E and Perez, M E and Levin, L A and Cha, H and Rouse, G W}
}
@article {Levin2013,
	title = {{Ecological release and niche partitioning under stress:lessons from dorvilleid polychaetes in sulfidic sediments at methane seeps}},
	journal = {Deep-Sea Research. Part II: Topical Studies in Oceanography},
	volume = {92},
	year = {2013},
	pages = {214{\textendash}233},
	abstract = {Organisms inhabiting methane seep sediments are exposed to stress in the form of high levels of hydrogen sulfide, which result mainly from sulfate reduction coupled to anaerobic methane oxidation. Dorvilleidae (Polychaeta) have successfully invaded this ecosystem, and multiple species in divergent genetic clades co-occur at high densities. At methane seeps in the NE Pacific off California and Oregon, the genera Ophryotrocha, Parougia and Exallopus are especially well represented. To test the hypothesis that dorvilleid coexistence is facilitated by niche partitioning through sulfide tolerance and trophic patterns, we examined dorvilleid species-specific patterns of occurrence and nutrition at methane seeps off Eel R. [ER] on the Californian continental slope and at Hydrate Ridge [HR] on the Oregon continental slope, and in two habitats (clam bed and microbial mat) characterized by lower and higher hydrogen sulfide levels, respectively. Microelectrode measurements of hydrogen sulfide enabled characterization of environmental sulfide levels for species sampled in background sediment cores and in colonization trays. Dorvilleids tolerated H2S levels from 10~$μ$M to over 2.6~mM, with the majority of species inhabiting sediments with similar environmental H2S concentrations (median 85{\textendash}100~$μ$M). Dorvilleid species richness was greater at HR than ER, but did not differ between clam bed and microbial mat habitats. Species distribution patterns reflected preferences for ER clam bed (lower sulfide levels), ER mat and HR clam bed (moderate sulfide levels), or HR mat (very high sulfide levels). Nutritional patterns, including trophic diversity and functional similarity, were examined using community stable isotope metrics based on $δ$15N and $δ$13C. Within each region, dorvilleid species exhibited multiple trophic strategies. Co-existing congeners typically exhibited distinct isotope signatures, suggesting trophic partitioning. Trophic diversity and $δ$15N range for whole assemblages (measured by Total Hull Area and Standard Elliptical Area using species averages) and functional redundancy or species packing (measured as distance to nearest neighbor) among species and individuals were generally higher at ER, where sulfide levels were lower than at HR. In contrast, average trophic diversity among individuals within a species was greater at HR than ER. In colonization experiments involving agar-based manipulations of sulfide in tray sediments that mimicked clam bed and mat conditions, dorvilleids comprised 68{\%} and 48{\%} of colonists at ER and HR, respectively. Dorvilleid species richness was higher in trays that were initially more sulfidic. However, habitat exerted stronger influence on the composition of colonizing dorvilleids than did sulfide additions. In the NE Pacific, regional, habitat and vertical (down-core) variation in hydrogen sulfide creates complex environmental heterogeneity at methane seeps, promoting high diversity of stress-tolerant taxa such as dorvilleid polychaetes.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {0967-0645},
	doi = {10.1016/j.dsr2.2013.02.006},
	url = {http://www.sciencedirect.com/science/article/pii/S0967064513000635},
	author = {Levin, L A and Ziebis, W and Mendoza, G and Bertics, V J and Washington, T and Gonzalez, J and Thurber, A R and Ebbe, B and Lee, R W}
}
@article {Levin2010,
	title = {{Diversity of bathyal macrofauna on the northeastern Pacific margin: the influence of methane seeps and oxygen minimum zones}},
	journal = {Marine Ecology},
	volume = {31},
	number = {1},
	year = {2010},
	pages = {94{\textendash}110},
	publisher = {Blackwell Publishing Ltd},
	abstract = {The upper continental slope in the northeastern Pacific Ocean is intercepted by a deep oxygen minimum zone (OMZ; 650{\textendash}1100 m) and punctuated by conduits of methane seepage. We examined the effects of these two dominant sources of heterogeneity on the density, composition and diversity of heterotrophic macrofauna off Hydrate Ridge, Oregon (OR; 800 m water depth), where the seeps co-occur within an OMZ, and off the Eel River, Northern California (CA; 500 m), where seeps are overlain by better oxygenated waters. We hypothesized that seeps (containing clam beds and microbial mats) should contribute a suite of distinct species to the regional margin species pool but that OMZ-associated hypoxia would dampen seep-related heterogeneity. Macrofaunal densities were highest (23,000{\textendash}33,510 ind{\textperiodcentered}m-2) in the CA seep sediments and in the OR near-seep samples, intermediate in the OR seep, CA near seep and CA and OR 500-m margin sediments (10,054{\textendash}19,777 ind{\textperiodcentered}m-2), and lowest in the CA and OR OMZ habitats at 800 m (4269{\textendash}7847 ind{\textperiodcentered}m-2). Annelids constituted over 50{\%} of the taxa in all but the CA clam bed and OR microbial mat sediments, where mollusks were abundant. Approximately 50{\%} of seep species appeared to be habitat endemic; species present in microbial mats largely formed a subset of those present in the clam beds. Dorvilleid and ampharetid polychaetes were dominant in the seep sediments; non-seep margin sediments at 500 and 800 m were populated heavily by branchiate polychaetes including cossurids and paraonids. Alpha diversity (Es[20] calculated per core) was lowest and rank 1 dominance was highest in the CA and OR microbial mat habitats. Pooled analyses of Es[100] revealed highest species richness in the CA clam bed and near-seep habitats (30.3 and 29.6, respectively), and lowest species richness in the OR microbial mat and near-seep habitats (16.5 and 17.9, respectively). Non-seep sediments (500 and 800 m) off both CA and OR were more homogeneous (55{\textendash}57{\%} within-habitat similarity) than clam bed and microbial mat sediments (only 32{\textendash}37{\%} within-habitat similarity). CA sediment macrofauna generally exhibit higher alpha diversity, and as habitats are combined, a higher rate of increase in the slope of the species accumulation curves than do OR margin macrofauna. Methane seeps in the NE Pacific introduce significant heterogeneity that increases margin biodiversity at multiple spatial scales. However, our hypothesis that the OMZ would lessen the seep contributions to diversity was not supported. The better oxygenated CA seeps at 500 m shared more of the background margin fauna (at 500 m) than did the OR seeps at 800 m (with OMZ fauna at 800 m). Geographical differences in the fluxes of methane-rich fluids and the increased reliance on chemosynthetic food sources with increased depth could explain these results.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {1439-0485},
	doi = {10.1111/j.1439-0485.2009.00335.x},
	url = {http://dx.doi.org/10.1111/j.1439-0485.2009.00335.x},
	author = {Levin, L A and Mendoza, G F and Gonzalez, J P and Thurber, A R and Cordes, E E}
}
@article {Basak2009,
	title = {{Carbon and oxygen isotope geochemistry of live (stained) benthic foraminifera from the Aleutian Margin and the Southern Australian Margin}},
	journal = {Marine Micropaleontology},
	volume = {70},
	number = {3-4},
	year = {2009},
	pages = {89{\textendash}101},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0377-8398},
	doi = {10.1016/j.marmicro.2008.11.002},
	url = {http://dx.doi.org/10.1016/j.marmicro.2008.11.002},
	author = {Basak, C and Rathburn, A E and Perez, M E and Martin, J B and Kluesner, J W and Levin, L A and De Deckker, P and Gieskes, J M and Abriani, M}
}
@article {Rathburn2009,
	title = {{Geological and biological heterogeneity of the Aleutian Margin (1965{\textendash}4822 m)}},
	journal = {Progress In Oceanography},
	volume = {80},
	number = {1-2},
	year = {2009},
	pages = {22{\textendash}50},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0079-6611},
	doi = {10.1016/j.pocean.2008.12.002},
	url = {http://dx.doi.org/10.1016/j.pocean.2008.12.002},
	author = {Rathburn, A E and Levin, L A and Tryon, M D and Gieskes, J M and Martin, J B and Perez, M E and Fodrie, F J and Neira, C and Fryer, G L and Mendoza, G F and McMillan, P A and Kluesner, J and Adamic, J and Ziebis, W}
}
@article {Levin2006,
	title = {{Recruitment response of methane-seep macrofauna to sulfide-rich sediments: An in situ experiment}},
	journal = {Journal of Experimental Marine Biology and Ecology},
	volume = {330},
	number = {1},
	year = {2006},
	pages = {132{\textendash}150},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0022-0981},
	doi = {10.1016/j.jembe.2005.12.022},
	url = {http://dx.doi.org/10.1016/j.jembe.2005.12.022},
	author = {Levin, L A and Ziebis, W and Mendoza, G F and Growney-Cannon, V and Walther, S}
}
@article {Levin2003,
	title = {{Spatial heterogeneity of macrofauna at northern California methane seeps: Influence of sulfide concentration and fluid flow}},
	journal = {Marine Ecology Progress Series},
	volume = {265},
	year = {2003},
	pages = {123{\textendash}139},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0171-8630},
	doi = {10.3354/meps265123},
	url = {http://dx.doi.org/10.3354/meps265123},
	author = {Levin, L A and Ziebis, W and Mendoza, G F and Growney, V A and Tryon, M D and Brown, K M and Mahn, C and Gieskes, J M and Rathburn, A E}
}
@article {Levin2002,
	title = {{Isotopic evidence for chemosynthesis-based nutrition of macrobenthos: The lightness of being at Pacific methane seeps}},
	journal = {Limnology and Oceanography},
	volume = {47},
	number = {5},
	year = {2002},
	pages = {1336{\textendash}1345},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {0024-3590},
	doi = {10.4319/lo.2002.47.5.1336},
	url = {http://www.aslo.org/lo/toc/vol{\_}47/issue{\_}5/1336.pdf},
	author = {Levin, L A and Michener, R H}
}
