Accurate benthic habitat maps are critical for resource management in coastal waters with competing uses. We used a 500 kHz phase-measuring bathymetric sonar (PMBS) and 900 kHz side-scan sonar to acquire seafloor data in estuarine and shelf environments. Grab samples and remotely operated vehicle video created geological and biological classifications for segmented maps produced by a backscatter clustering program. PMBS improves regional map resolution (<1 m), reduces the need for direct sampling, extends information on sedimentbiological relationships to larger areas, and allows measurements of bedforms. Auto-segmentation was successful in environments with highly contrasting acoustic signatures and meters-scale homogeneity. Patchier communities are identifiable in PMBS data. Species preferences for sediment (i.e., tubeworm preference for sediment without shell hash) allowed us to determine potential habitat without identifying individual organisms in acoustic data. PMBS with sufficient ground-truthing offers an efficient way to map seafloor characteristics, which is critical in marine spatial planning efforts.

During E/V Nautilus NA072 expedition, multibeam sonar surveys located over 800 individual bubble streams rising from the Cascadia Margin between the Strait of Juan de Fuca and Cape Mendocino at depths between 104 and 2,073 m. Gas bubbles were collected directly at the seafloor using gastight sampling bottles. These bubbles were consistently composed of over 99% methane with traces of carbon dioxide, oxygen, nitrogen, noble gases, and more rarely higher hydrocarbons. A common previous view was that a biogenic source was responsible for seeps from within the gas hydrate stability zone (upper limit near 500‐m isobath) and a thermogenic source was responsible for seeps from the upper slope and the shelf. Higher hydrocarbons in deep seeps with a biogenic methane signature, as well as the lack of higher hydrocarbons in some shallower seeps with a thermogenic methane signature, show that the origin of the gas cannot simply be attributed to seep location on the margin. Instead, mixing and oxidation processes play an integral role. 3He/4He ratios at Coquille SW point to a contribution of 30% mantle helium, whereas all the other investigated sites are characterized by a crustal helium signature. Hence, the Coquille SW seeps are directly or indirectly connected to the mantle or to very young oceanic crust. The detection of mantle helium in these seeps can thus be used as a tracer for deep‐reaching fracture systems and their changing pathways.

Lim et al. spe 483-01 page 86 bodies where scientifi c investigation is a key driver of exploration. In order to explore and collect samples underwater at Pavilion Lake, humans must, as they do in space, coordinate with unmanned robotic systems and contend with limitations associated with communications, visualization, and sampling of their environments, and their life support systems (LSS) (Lim et al., 2010). These working constraints are not simulated, but are real and inextricable from the PLRP's activities. As such, Pavilion Lake has become an important analog research environment in which to garner operational information applicable to the design of human planetary exploration strategies. The goal of this paper is to present a historical synopsis of analog science and exploration activities at Pavilion Lake with the specifi c aim of highlighting the unique contributions of the PLRP to the development of human planetary exploration strategies. To ensure that the complexity and richness of the project are properly captured in this paper, two appendices are included that document some of the PLRP's additional initiatives and activities (e.g., education and public outreach).

Exploration of the deep ocean (>200 m) is taking on added importance as human development encroaches. Despite increasing oil and natural gas exploration and exploitation, the deep ocean of Trinidad and Tobago is almost entirely unknown. The only scientific team to image the deep seafloor within the Trinidad and Tobago Exclusive Economic Zone was from IFREMER in the 1980s. That exploration led to the discovery of the El Pilar methane seeps and associated chemosynthetic communities on the accretionary prism to the east of Trinidad and Tobago. In 2014, the E/V Nautilus, in collaboration with local scientists, visited two previously sampled as well as two unexplored areas of the El Pilar site between 998 and 1,629 m depth using remotely operated vehicles. Eighty-three megafaunal morphospecies from extensive chemosynthetic communities surrounding active methane seepage were observed at four sites. These communities were dominated by megafaunal invertebrates including mussels (Bathymodiolus childressi), shrimp (Alvinocaris cf. muricola), Lamellibrachia sp. 2 tubeworms, and Pachycara caribbaeum. Adjacent to areas of active seepage was an ecotone of suspension feeders including Haplosclerida sponges, stylasterids and Neovermilia serpulids on authigenic carbonates. Beyond this were large Bathymodiolus shell middens. Finally there was either a zone of sparse octocorals and other nonchemosynthetic species likely benefiting from the carbonate substratum and enriched production within the seep habitat, or sedimented inactive areas. This paper highlights these ecologically significant areas and increases the knowledge of the biodiversity of the Trinidad and Tobago deep ocean. Because methane seepage and chemosynthetic communities are related to the presence of extractable oil and gas resources, development of best practices for the conservation of biodiversity in Trinidad and Tobago waters within the context of energy extraction is critical. Potential impacts on benthic communities during oil and gas activities will likely be long lasting and include physical disturbance during drilling among others. Recommendations for the stewardship of Amon et al.Seep Communities Off Trinidad and Tobago these widespread habitats include: (1) seeking international cooperation; (2) holding wider stakeholder discussions; (3) adopting stringent environmental regulations; and (4) increasing deep-sea research to gather crucial baseline data in order to conduct appropriate marine spatial planning with the creation of marine protected areas.