Description: Along mid-ocean ridges, submarine venting has been found at all spreading rates and in every ocean basin. By contrast, intraplate hydrothermal activity has only been reported from five locations, worldwide. Here we extend the time series at one of those sites, Teahitia Seamount, which was first shown to be hydrothermally active in 1983 but had not been revisited since 1999. Previously, submersible investigations had led to the discovery of low-temperature (≤30°C) venting associated with the summit of Teahitia Seamount at ≤1500 m. In December 2013 we returned to the same site at the culmination of the US GEOTRACES Eastern South Tropical Pacific (GP16) transect and found evidence for ongoing venting in the form of a non-buoyant hydrothermal plume at a depth of 1400 m. Multi-beam mapping revealed the same composite volcano morphology described previously for Teahitia including four prominent cones. The plume overlying the summit showed distinct in situ optical backscatter and redox anomalies, coupled with high concentrations of total dissolvable Fe (≤186 nmol/L) and Mn (≤33 nmol/L) that are all diagnostic of venting at the underlying seafloor. Continuous seismic records from 1986-present reveal a ∼15 year period of quiescence at Teahitia, following the seismic crisis that first stimulated its submersible-led investigation. Since 2007, however, the frequency of seismicity at Teahitia, coupled with the low magnitude of those events, are suggestive of magmatic reactivation. Separately, distinct seismicity at the adjacent Rocard seamount has also been attributed to submarine extrusive volcanism in 2011 and in 2013. Theoretical modeling of the hydrothermal plume signals detected suggest a minimum heat flux of 10 MW at the summit of Teahitia. Those model simulations can only be sourced from an area of low-temperature venting such as that originally reported from Teahitia if the temperature of the fluids exiting the seabed has increased significantly, from ≤30°C to ∼70°C. These model seafloor temperatures and our direct plume observations are both consistent with reports from Loihi Seamount, Hawaii, ∼10 year following an episode of seafloor volcanism. We hypothesize that the Society Islands hotspot may be undergoing a similar episode of both magmatic and hydrothermal reactivation.

Description: Anthropogenically driven climate change will rapidly become Earth's dominant transformative influence in the coming decades. The oceanic biological pump—the complex suite of processes that results in the transfer of particulate and dissolved organic carbon from the surface to the deep ocean—constitutes the main mechanism for removing CO2 from the atmosphere and sequestering carbon at depth on submillennium time scales. Variations in the efficacy of the biological pump and the strength of the deep ocean carbon sink, which is larger than all other bioactive carbon reservoirs, regulate Earth's climate and have been implicated in past glacial-​interglacial cycles. The numerous biological, chemical, and physical processes involved in the biological pump are inextricably linked and heterogeneous over a wide range of spatial and temporal scales, and they influence virtually the entire ocean ecosystem. Thus, the functioning of the oceanic biological pump is not only relevant to the modulation of Earth's climate but also constitutes the basis for marine biodiversity and key food resources that support the human population. Our understanding of the biological pump is far from complete. Moreover, how the biological pump and the deep ocean carbon sink will respond to the rapid and ongoing anthropogenic changes to our planet—including warming, acidification, and deoxygenation of ocean waters—remains highly uncertain. To understand and quantify present-day and future changes in biological pump processes requires sustained global observations coupled with extensive modeling studies supported by international scientific coordination and funding

Description: Author Posting. © Oceanography Society, 2007. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 20, 1 (2007): 30-41.

Description: The discovery of hydrothermal vents and the unique, often endemic fauna that inhabit them represents one of the most extraordinary scientific discoveries of the latter twentieth century. Not surprisingly, after just 30 years of study of these remarkable—and extremely remote—systems, advances in understanding the animals and microbial communities living around hydrothermal vents seem to occur with every fresh expedition to the seafloor. On average, two new species are described each month—a rate of discovery that has been sustained over the past 25–30 years. Furthermore, the physical, geological, and geochemical features of each part of the ridge system and its associated hydrothermal-vent structures appear to dictate which novel biological species can live where. Only 10 percent of the ridge system has been explored for hydrothermal activity to date (Baker and German, 2004), yet we find different diversity patterns in that small fraction. While it is well known that species composition varies along discrete segments of the global ridge system, this “biogeographic puzzle” has more pieces missing than pieces in place.

Description: E. Ramirez-Llodra is supported by the ChEss-Census of Marine Life program (A.P. Sloan Foundation), which is kindly acknowledged. C.R. German also acknowledges support from ChEss- Census of Marine Life and further support from the Natural Environment Research Council (UK) and from the US National Science Foundation (NSF) and National Oceanic and Atmospheric Administration (NOAA). T. Shank acknowledges support from NSF, the US National Aeronautic and Space Administration Astrobiology Program, NOAA-Ocean Exploration, and the Deep-Ocean Exploration Institute at the Woods Hole Oceanographic Institution.

Description: Author Posting. © Oceanography Society, 2007. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 20, 4 (2007): 52-61.

Description: Human-occupied submersibles, towed vehicles, and tethered remotely operated vehicles (ROVs) have traditionally been used to study the deep seafloor. In recent years, however, autonomous underwater vehicles (AUVs) have begun to replace these other vehicles for mapping and survey missions. AUVs complement the capabilities of these pre-existing systems, offering superior mapping capabilities, improved logistics, and better utilization of the surface support vessel by allowing other tasks such as submersible operations, ROV work, CTD stations, or multibeam surveys to be performed while the AUV does its work. AUVs are particularly well suited to systematic preplanned surveys using sonars, in situ chemical sensors, and cameras in the rugged deep-sea terrain that has been the focus of numerous scientific expeditions (e.g., those to mid-ocean ridges and ocean margin settings). The Autonomous Benthic Explorer (ABE) is an example of an AUV that has been used for over 20 cruises sponsored by the National Science Foundation (NSF), the National Oceanic and Atmospheric Administration (NOAA) Office of Ocean Exploration (OE), and international and private sources. This paper summarizes NOAA OE-sponsored cruises made to date using ABE.

Description: Author Posting. © Oceanography Society, 2007. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 20, 1 (2007): 152-161.

Description: Autonomous and remotely operated underwater vehicles play complementary roles in the discovery, exploration, and detailed study of hydrothermal vents. Beginning with clues provided by towed or lowered instruments, autonomous underwater vehicles (AUVs) can localize and make preliminary photographic surveys of vent fields. In addition to finding and photographing such sites, AUVs excel at providing regional context through fine-scale bathymetric and magnetic field mapping. Remotely operated vehicles (ROVs) enable close-up inspection, photomosaicking, and tasks involving manipulation of samples and instruments. Increasingly, ROVs are used to conduct in situ seafloor experiments. ROVs can also be used for fine-scale bathymetric mapping with excellent results, although AUVs are usually more efficient in such tasks.

Description: Author Posting. © The Oceanography Society, 2019. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 32, no. 1, supplement (2019): 48-49.

Description: Author Posting. © The Oceanography Society, 2019. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 32, no. 1, supplement (2019): 46-47.

Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in German, C., Blackman, D., Fisher, A., Girguis, P., Hand, K., Hoehler, T., Huber, J., Marshall, J., Pietro, K., Seewald, J., Shock, E., Sotin, C., Thurnherr, A., & Toner, B. Ocean system science to inform the exploration of ocean worlds. Oceanography, 35(1), (2022): 16-20, https://doi.org/10.5670/oceanog.2021.411.

Description: Ocean worlds provide fascinating opportunities for future ocean research. They allow us to test our understanding of processes we consider fundamental to Earth’s ocean and simultaneously provide motivation to explore our ocean further and develop new technologies to do so. In parallel, ocean worlds research offers opportunities for ocean scientists to provide meaningful contributions to novel investigations in the coming decades that will search for life beyond Earth. Key to the contributions that oceanographers can make to this field is that studies of all other ocean worlds remain extremely data limited. Here, we describe an approach based on ocean systems science in which theoretical modeling can be used, in concert with targeted laboratory experimentation and direct observations in Earth’s ocean, to predict what processes (including those essential to support life) might be occurring on other ocean worlds. In turn, such an approach would help identify new technologies that might be required for future space missions as well as appropriate analog studies that could be conducted on Earth to develop and validate such technologies. Our approach is both integrative and interdisciplinary and considers multiple domains, from processes active in the subseafloor to those associated with ocean-ice feedbacks.

Description: This work is supported by NASA Astrobiology Program award # 80NSSC19K1427 Exploring Ocean Worlds: Ocean System Science to Support the Search for Life.

Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in German, C., Institution, W., Arrigo, K., Murray, A., & Rhoden, A. Planetary oceanography: leveraging expertise among earth and planetary science. Oceanography. 35(1), (2022): 10-15, https://doi.org/10.5670/oceanog.2021.410.

Description: The study of planetary oceanography is a new and exciting field of research. While humanity’s formal scientific studies of Earth’s ocean began nearly 150 years ago with the launch of the Challenger Expedition (Thomson et al., 1873), the study of oceans beyond Earth commenced only in this millennium. The first confirmation of an extensive saltwater ocean anywhere beyond Earth came relatively late within the lifetime of NASA’s Galileo mission (1989–2003; Kivelson et al., 2000), but continuing exploration has now revealed compelling evidence for large-volume watery oceans on five ice-covered moons of our outer solar system (Figure 1), with as many as 10–20 candidate moons and dwarf planets also under consideration (Hendrix et al., 2019). Of the five confirmed ocean worlds (Jupiter’s moons Europa, Callisto, and Ganymede; Saturn’s moons Enceladus and Titan), three have oceans so deep that a high-pressure form of ice develops deep within the ocean, beneath the liquid water but overlying any rocky interior (Nimmo and Papallardo, 2016). As a consequence, the watery ocean is trapped within an “ice sandwich.” By contrast, the other two confirmed ocean worlds (Europa and Enceladus) have oceans that are in direct contact with a rocky interior.

Description: This work was funded through support of NASA Awards 80NSSC19K1427 to CG, 80NSSC20K1258 to KRA, 80NSSC19K0920 to AEM, and 80NSSC19K0919 to ARR.