The deep ocean below 200 m water depth is the least observed, but largest habitat on our planet by volume and area. Over 150 years of exploration has revealed that this dynamic system provides critical climate regulation, houses a wealth of energy, mineral, and biological resources, and represents a vast repository of biological diversity. A long history of deep-ocean exploration and observation led to the initial concept for the Deep-Ocean Observing Strategy (DOOS), under the auspices of the Global Ocean Observing System (GOOS). Here we discuss the scientific need for globally

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Submersible exploration of the Samoan hotspot revealed a new, 300-m-tall, volcanic cone, named Nafanua, in the summit crater of Vailulu'u seamount. Nafanua grew from the 1,000-m-deep crater floor in <4 years and could reach the sea surface within decades. Vents fill Vailulu'u crater with a thick suspension of particulates and apparently toxic fluids that mix with seawater entering from the crater breaches. Low-temperature vents form Fe oxide chimneys in many locations and up to 1-m-thick layers of hydrothermal Fe floc on Nafanua. High-temperature (81°C) hydrothermal vents in the northern moat (945-m water depth) produce acidic fluids (pH 2.7) with rising droplets of (probably) liquid CO 2. The Nafanua summit vent area is inhabited by a thriving population of eels (Dysommina rugosa) that feed on midwater shrimp probably concentrated by anticyclonic currents at the volcano summit and rim. The moat and crater floor around the new volcano are littered with dead metazoans that apparently died from exposure to hydrothermal emissions. Acid-tolerant polychaetes (Polynoidae) live in this environment, apparently feeding on bacteria from decaying fish carcasses. Vailulu'u is an unpredictable and very active underwater volcano presenting a potential long-term volcanic hazard. Although eels thrive in hydrothermal vents at the summit of Nafanua, venting elsewhere in the crater causes mass mortality. Paradoxically, the same anticyclonic currents that deliver food to the eels may also concentrate a wide variety of nektonic animals in a death trap of toxic hydrothermal fluids.currents ͉ habitats ͉ hydrothermal ͉ vents ͉ eels S eamounts, submerged isolated mountains in the oceans, are among the most poorly understood major morphological features on Earth, offering important research targets for ocean sciences. Seamount research, which involves fields as diverse as volcanology, geology, geochemistry, geophysics, physical oceanography, and marine biology, has yielded crucial insights into the absolute motion of the tectonic plates (1), the rheology and state of stress of the underlying lithosphere (2, 3), the chemical make-up of Earth's mantle (4), and the role of hypoxia in benthic animal distributions (5). Seamounts offer unique habitats for nektonic and benthic life, including both microbes and metazoans (6, 7). The topography of seamounts can substantially enhance internal ocean tides, providing powerful ''stirring rods'' for mixing the oceans (8) and creating local currents that transport nutrients and retain larvae (9) and concentrate commercially important fishes (10).We report here the initial, integrated results from recent volcanological, biological, and oceanographic explorations of Vailulu'u Seamount (14°13ЈS; 169°04ЈW), an active submarine volcano located 45 km east of the easternmost island in the Samoan archipelago. Our data come largely from three short oceanographic cruises in March-July, 2005. A cruise on the R͞V Kilo Moana (KM) in April 2005 included 3 days of bathymetric mapping, hydrographic profiling, and geol...

Abstract. The contribution of carbonate-producing benthic organisms to the global marine carbon budget has been overlooked, the prevailing view being that calcium carbonate (CaCO 3 ) is predominantly produced and exported by marine plankton in the ''biological pump.'' Here, we provide the first estimation of the global contribution of echinoderms to the marine inorganic and organic carbon cycle, based on organism-level measurements from species of the five echinoderm classes. Echinoderms' global CaCO 3 contribution amounts to ;0.861 Pg CaCO 3 /yr (0.102 Pg C/yr of inorganic carbon) as a production rate, and ;2.11 Pg CaCO 3 (0.25 Pg C of inorganic carbon) as a standing stock from the shelves, slopes, and abyssal depths. Echinoderm inorganic carbon production (0.102 Pg C/yr) is less than the global pelagic production (0.4-1.8 Pg C/yr) and similar to the estimates for carbonate shelves globally (0.024-0.120 Pg C/yr Áyr À1 as inorganic carbon) for the slope on a global scale. The biogeography of the CaCO 3 standing stocks of echinoderms showed strong latitudinal variability. More than 80% of the global CaCO 3 production from echinoderms occurs between 0 and 800 m, with the highest contribution attributed to the shelf and upper slope. We provide a global distribution of echinoderm populations in the context of global calcite saturation horizons, since undersaturated waters with respect to mineral phases are surfacing. This shallowing is a direct consequence of ocean acidification, and in some places it may reach the shelf and upper slope permanently, where the highest CaCO 3 standing stocks from echinoderms originate. These organism-level data contribute substantially to the assessment of global carbonate inventories, which at present are poorly estimated. Additionally, it is desirable to include these benthic compartments in coupled global biogeochemical models representing the ''biological pump'' and its feedbacks, since at present all efforts have focused on pelagic processes, dominated by coccolithophores. The omission of the benthic processes from modeling will only diminish the understanding of elemental fluxes at large scales and any future prediction of climate change scenarios.