Recent geological investigations and offshore drillings have revealed the great prospects of the gas hydrate resources in the Quaternary sediments of the Qiongdongnan Basin (QDNB). Pore-filling gas hydrates were first discovered in the sand layers during the 2019 gas hydrate drilling expedition (GMGS6) in the QDNB. Logging data, 2D/3D seismic data, cores, and grain size analysis were used to study

The naturally-occurring radionuclides protactinium-231 (231Pa) and thorium-230 (230Th) are produced at approximately uniform rates in the ocean and thought to be removed from the water column through a reversible exchange with settling particles. Recent measurements along the U.S. GEOTRACES North Atlantic transect (GA03) revealed two features which are at odds with current understanding about 231Pa and

In this work, a consolidated experimental apparatus for measuring the density of liquids, such as high pressure and metastable states, based on the isochoric method, was exploited to measure thermal properties of seawater. Density of standard seawater was measured in a wide range of temperature and pressure, specifically from (261.15 to 313.15) K and up to 110 MPa. All terms contributing to the uncertainty

High resolution acoustic data, together with high-definition photomosaic images and video observations of the Formosa Ridge Cold Seep Site were obtained using a remotely operated vehicle (ROV). Seabed features of the cold seep site were described in detail and the scales and distribution patterns of these features displayed on the seabed were quantitatively analyzed. The cold seep site is characterized

We present tritium (3H) and helium isotope (δ3He) data from the South China Sea (SCS), to estimate apparent oxygen utilization rates (AOURs). The observed δ3He values are close to the theoretical solubility equilibrium value of -1.7% in the upper mixed layer, followed by an increase with depth down to ~1500 m. Below 1500 m depth, δ3He is homogenously distributed with a value of 20.9% ± 1.0%. The distribution

This study focused on radiolarian diversity in the deep-sea sediments of the East Indian Ocean (EIO) to demonstrate their potential as a paleoceanogrpahic proxy. Radiolarians are in general abundant in deep-sea sediment of the EIO. However, around Sri Lanka, their abundances decrease potentially because of terrigenous matter inputs. The significantly high abundance of radiolarians in the northern Ninety-East

Seven short cores collected along two transects from the shelf to trench bottom in the New Britain Trench (NBT) area, Papua New Guinea (PNG), were studied to illuminate the provenance and burial of sediments across the shelf-trench continuum. Here, we present geochemical data, including major, minor and rare earth elements, bulk and clay mineralogy, grain size, and Sr–Nd isotopes. The results indicate

Holopelagic animals were long assumed to have widespread geographic distributions due to the failure to recognize hydrographic species' barriers in the open ocean. As molecular genetic tools are more commonly used to study the ocean's inhabitants, diversity is found to be substantially higher than when inferred from morphological taxonomies alone. Here, we investigate the morphological and genetic

In this paper we analyze how oceanic circulation affects sediment deposition along a sector of the Ross Sea continental margin, between the Iselin Bank and the Hillary Canyon, and how these processes evolved since the Late Miocene. The Hillary Canyon is one of the few places around the Antarctic continental margin where the dense waters produced onto the continental shelf, mainly through brine rejection

The Alarcón Rise (AR) hydrothermal system recently discovered in the Southern Gulf of California is characterized by the presence of black smokers, fluids with temperatures up to 360 °C, high concentrations of metal-sulfides and H2S. The trophic structure and the energy flow in the vent community were determined through the carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) isotopic signatures of 19

The Eastern Mediterranean Sea (EMS), is ultra-oligotrophic with unusual anti-estuarine circulation. It is P depleted and the limited enrichment studies which have been carried out, suggest seasonal changes in nutrient limitation. In this study high sensitivity dissolved nutrients (and associated parameters) were determined monthly over an annual cycle at a pelagic location in the SE Levantine basin

The Benthic Invertebrates of Icelandic Waters programme (BIOICE) was conducted between 1991 and 2004, for the purpose of gathering specimens within the Icelandic Exclusive Economic Zone (59° 58′N – 69° 35‘N and 30° 52’W – 5° 34′W). In total 12961 asteroid specimens were collected from 654 sampling stations, which comprises 63% of all sampling stations. Sampling depths were between 20 and 2700 m. Total

High hydrostatic pressure (HHP) is a common factor in the deep sea and provides an ignorable parameter of consideration in all studies related to deep life. High-temperature environments in the deep sea, mainly including hydrothermal vents and deep sediments in the subseafloor, support enormous amounts of biomass, productivity, and diversity of life. Many microbes living there are usually (hyper)thermophilic

The Alboran Sea and the Balearic Islands are two contrasting areas in terms of primary productivity. The former is among the most productive areas of the whole Mediterranean Sea, whereas the Balearic Islands is among the less productive ones in the western Mediterranean. The two areas also show different patterns in the bottom trawl fishing footprint. In the Alboran Sea, the fishing effort on the upper

Deep-sea habitats are home for a variety of yet poorly known fish species, some of which display specialized life strategies, as is the case of Bythitidae and Zoarcidae. With the purpose of elucidating biological and ecological aspects of representatives of these families in NW Mediterranean waters, a large dataset based on 599 specimens of Cataetyx alleni, 30 C. laticeps and 284 Melanostigma atlanticum

In a 1976 lecture entitled “Life at low Reynolds Number,” Edward Purcell examined constraints on mobility of small aquatic animals defining the energetic challenge as “to move far enough to beat diffusion.” We show that the essential requirement is the need to do sufficient work to overcome the activation energy of viscous flow. Raman spectroscopy shows that sea water is dominated (78–85%) by the hydrogen

In this study on the basis of various data sets we traced formation of a ‘dome’- shaped density structure over the Central Bank - an important morphological element of the Barents Sea bottom topography. The major conclusion, which follows from the performed analysis, is that under changed conditions at the sea surface, transformation of thermohaline structure during the cold season principally differs

Changes of marine paleoproductivity could reflect the history of marine biogenic cycle process, and exploring the evolution and mechanism of marine productivity are important for understanding the global biogenic factor cycle and its roles in past, present and future climate change. Based on the analysis of biogenic silica (BSi) in core ADM-159 and core BoB-56 from the northeastern Indian Ocean, high-resolution

The growth of ferromanganese (FeMn) crusts on soft substrates is uncommon. FeMn crusts generally accrete on hard-rock surfaces, where sedimentation rates are low and the rocks free of sediment cover. Here we use X-ray Powder Diffraction, Fourier Transform-Infra Red spectroscopy, Raman spectroscopy, X-ray Computed Micro-Tomography, Scanning Electron Microscopy and Particle Size Distribution analysis

Octocorals are prominent habitat builders in deep-sea ecosystems. The octocorals Dentomuricea aff. meteor and Viminella flagellum are common deep-sea octocoral species in the Azores Archipelago, where they form dense, structurally complex and diverse communities between 150 and 600 m of depth. The objective of this study was to determine the reproductive biology of the studied species, including basic

Deep-ocean biology has been the least explored—although rapidly growing—area of research. In particular, behavior, reproduction and ecology of deeper-living squids remain poorly documented due to the extreme difficulties of encountering and capturing them. Here we report on a mature/maturing female giant squid, Architeuthis dux, caught as by-catch in a fishery set-net. Microsatellite paternity analysis

For a century, the discovery of ferromanganese (Fe–Mn) nodules in the World Ocean was universally and indisputably credited to the Challenger circum-global oceanographic expedition of 1872–1876, during which the first manganese nodules and crusts were dredged up from the sea floor in February–March 1873. A century later, a counterclaim appeared in the literature, crediting Nordenskiöld's expedition

Fluorescence sensors mounted on unmanned underwater gliders open new ways of investigation to detect dissolved hydrocarbons in seawater. A glider was deployed for 20 days to monitor biogeochemical and physical signals associated with natural hydrocarbon seepages within the first 700 m in the Angolan waters. The glider was equipped with fluorometers (MiniFluo-UV) to measure the concentrations of polycyclic

A range extension for the spiny tailed skate, Bathyraja spinicauda is presented here, evidenced by an egg nursery observed atop a ridge on the Charlie Gibbs Fracture Zone along the Mid Atlantic Ridge. The species identification used an integrated taxonomic approach based on egg morphology and mtCOI barcoding of intact embryos. The egg nursery was mapped, and key environmental descriptors characterised:

Recent observations report a poleward shift in several of the world’s western boundary current extensions in response to a warming climate. However, the nature and variability of the Agulhas Return Current (ARC) is still relatively unknown, leading to uncertainty in its response to gyre intensification. The objective of this work is to investigate meridional migration and eddy kinetic energy (EKE)

Summer plankton surveys were conducted in 2015–2017 to characterize the distribution and abundance of squid paralarvae in epipelagic waters of the northern Gulf of Mexico (Gulf). Paralarvae present at stations sampled were from 12 families, with the most abundant being Ommastrephidae (flying squids), Enoploteuthidae (armed squids) and Onychoteuthidae (hooked squids). Mean density and percent frequency

Total dissolvable and dissolved aluminum (TDAl, DAl) and manganese (TDMn, DMn) concentrations were measured at 12 stations in and around the Solomon Sea in 2012 as part of the GEOTRACES GP-12 cruise. These data were used to determine the potential for the Solomon Sea to act as a source of Al and Mn to the Equatorial Undercurrent (EUC). From a net budget perspective, waters entering the Solomon Sea

Siliceous planktons are valuable indicators of the environmental conditions in both modern and past marine settings. However, in contrast to diatoms and radiolarians, other siliceous micro- and nanoplankton in the Arctic Ocean have been rarely explored. In this study, silicoflagellates, endoskeletal dinoflagellate Actiniscus pentasterias and chrysophyte cysts were investigated in one-year mooring sediment

Cephalopods are an important component of Southern Ocean food webs but studies analysing their habitat and trophic ecology are scarce. Here, we use the Antarctic toothfish Dissostichus mawsoni as a biological sampler of Southern Ocean's cephalopods in the Ross, Amundsen, and D'Urville Seas. Ten cephalopod taxa were identified in the diet of the Antarctic toothfish, with Pareledone turqueti and Moroteuthopsis

This study investigates the physical processes and mechanisms driving the interannual variability of deep convective intensity in the Greenland Sea from 1993 to 2016. The intensity of deep convection is derived using the traditional Maximum Mixed Layer Depth, the total surface area with the monthly-mean mixed layer depth exceeding 800 m and various indices. All metrics show that the intensity of convection

The nitrogen isotopic composition of nitrate and suspended particulate nitrogen (PN) in the upper 500 m water column along a transect in the western Bering Sea was analyzed to characterize the nitrogen cycle in summer. The δ15N of nitrate (δ15N–NO3) increases into the surface, in strong correlation with the upward decrease in nitrate concentration, reflecting the effect of nitrate assimilation by phytoplankton

The deep-sea red and blue shrimp Aristeus antennatus is a commercially valuable species that occurs in the northwestern Mediterranean Sea where ripe females have been found in fishing areas. In the Palamós harbor, a local management plan restricts fishing in certain locations to sustain the resource. However, little is known about the dispersal of larvae; specifically, it is not known how far larvae

Gutless tubeworms obtain their nutrition from their bacterial endosymbiotic partners, and the metazoan hosts provide the bacteria with sulfide, carbon dioxide, and molecular oxygen taken up through the plume. At seeps, tubeworms take up sulfide using their posterior end, allowing them to fix carbon dioxide and synthesize organic molecules. Compared to bulk tissue isotope compositions, lipid biomarkers

Food availability in fjords is unusual among deep-sea environments due to the increased availability of nutritional sources that are comparatively rare in the open sea, such as influxes of macrophytodetritus and terrestrial organic matter. In open waters, these deep-sea ‘organic falls’ have been shown to increase beta diversity in comparison to surrounding, unenriched sediments, and support a range

The Black Sea is characterized by powerful summer coccolithophore blooms with strong interannual variability. In this paper, we used satellite and Bio-Argo measurements to show that the emergence of extremely strong blooms in several years was caused by intense vertical entrainment of nutrients from deep isopycnal layers during winter convection. In the highly stratified Black Sea, the depths of maximum

Variability in mesopelagic fish assemblages of the deep-scattering layer were explored in relation to mesoscale anticyclonic (warm-core) eddies in the western North Atlantic Ocean. Exploratory fishing with a mid-water herring trawl was combined with oceanographic sampling aboard the RV Celtic Explorer in the Spring of 2015 and 2016 to characterize mesopelagic fish assemblages along transects through

Internal solitary waves (ISWs) make important contributions to the energy cascade, ocean mixing and material transport in the ocean. However, there are few observational studies on the vertical structure of ISWs. In this article, we describe and analyze 11 ISWs near Dongsha Atoll in the South China Sea directly observed using two-dimensional seismic data. We calculate the vertical structures of these

Cold-seep chemosynthetic communities are found in patchy areas where methane and other hydrocarbons leak through the seafloor. Although relatively common in continental margins, chemosynthetic communities in the Caribbean region are poorly known. Their existence in Colombian waters has been suggested by the presence of carbonates and specimens of seep- specialist families obtained through trawling

A sensitive and automated method for underway and onboard analysis of trace ammonium in seawater was established using on-line solid phase extraction and fluorescence detection. Ammonium reacted with o-phthalaldehyde and sulfite to produce isoindole derivative that was concentrated on a hydrophilic lipophilic balanced (HLB) cartridge and then rapidly eluted with ethanol and measured using a fluorescence

Copepoda is the most diverse and abundant taxon at deep-sea hydrothermal vents, contributing significantly to the biodiversity and thus is important in maintaining ecosystem functioning. To date we lack knowledge on meiofauna, specifically copepod community dynamics, in the entire region of the Eastern Lau Spreading Center. We explore abundance and diversity of copepods associated with foundation species

The legend of the “kraken” has captivated humans for millennia, yet our knowledge of the large deep-sea cephalopods that inspired this myth remains limited. Conventional methods for exploring the deep sea, including the use of nets, manned submersibles, and remotely operated vehicles (ROVs), are primarily suited for studying slow-moving or sessile organisms, and baited camera-traps tend to attract

Long-term interannual variations in the benthic community structure are well-known from abyssal plains in the North Atlantic and North Pacific, where rapid responses to changes in the environment by first-order opportunists modify overall species composition. To increase our knowledge of the long-term variations of deep-sea benthic communities in the North-East Atlantic, we studied the response of

An important pathway for CO2 sinking in the ocean is via the “biological pump”, driven by the production of particulate organic carbon (POC) in the surface ocean and its subsequent export to the deeper ocean via vertical settling. Here we examine the vertical fluxes of POC in the continental slope of the northern Gulf of Mexico by utilizing the short-lived radionuclide pair 210Po - 210Pb. The total

Polymetallic nodules increase habitat heterogeneity in some abyssal benthic ecosystems by providing hard substrate. Besides their important role in structuring ecosystems, polymetallic nodules have high grades of valuable minerals and are a target of likely future exploitation, particularly in the Pacific Clarion-Clipperton Zone (CCZ). Mining activities will remove hard substrate and sediment and cause

The Pourtalès Terrace is an exposed hard-bottom platform located south of the Florida Keys in 200–450 m depth with a diverse deep-sea coral ecosystem dominated by stylasterid hydrocorals, octocorals, and sponges that supports recreational and commercial fisheries. Portions of the Terrace have been designated as managed areas in the absence of detailed habitat maps, which hampers identifying ecological

The yellowfin tuna (Thunnus albacares) is a widely distributed, migratory species that supports valuable commercial fisheries throughout their range. Management of migratory species requires knowledge of movement, mixing and key life history parameters such as growth rate, natural and fisheries mortality. Current management is based on the assumptions that the species is highly migratory and populations

The encountering of the subtropical Brazil Current (BC) and the subantarctic Malvinas Current (MC) along the western margin of the Argentine Basin forms the Brazil-Malvinas Confluence (BMC), one of the most intense open-ocean fronts in the world ocean and a site for the formation of intermediate water masses. Here, we provide a comprehensive description of the BMC based on physical and biogeochemical

Self-splicing mitochondrial introns are a rarely reported phenomenon in animals, with a sparse and uneven distribution confined to some species of sponges, corals, placozoans, and a single species of annelid. Here, we describe a mitochondrial intron present only in some populations of Phakellia robusta, a sponge distributed across the North-east Atlantic deep-sea. The mitochondrial intron of P. robusta

Deep-sea hydrothermal vents are a challenging environment inhabited by very specialized species. To reap the benefits of the local primary production, species need to cope with a number of constraints among which low oxygen is probably the most basic. This hypoxia is further complicated by the highly variable temperature these species experience. We studied the response of deep-sea hydrothermal species

The fate of carbon while passing through the rocky subseafloor of the ocean has direct implications on the global carbon cycle now and over geologic time, as well as the abundance and distribution of subseafloor life. Many organic geochemical studies require larger volumes of fluids than traditional hydrothermal samplers can provide, and also require rigorous steps to be taken to prevent contamination

Every year >100 killer whales accumulate on the continental slope near Bremer Bay in the western Great Australian Bight from late austral spring to early autumn (January–April), which can be regarded as a natural wonder. For unknown reasons, the whales tend to feed in the same confined region over a seafloor plateau near the head of the Hood Canyon, where the total water depth is ∼800–1000 m. The hypothesis

Asgard archaea, believed to be the ancestor of eukaryotes, constitute a new superphylum prevalent in diverse sediment environments. Their distribution and metabolic potentials are diversified and elusive. In the present study, the distribution and genomic characteristics of Asgard archaea in the Haima cold seep of the South China Sea (SCS) were investigated. In total, we obtained 48 high-quality metagenome-assembled

Low-temperature hydrothermal systems are generally dominated by Fe–Si oxyhydroxide deposits. However, the formation process and mechanism of modern hydrothermal Fe–Si oxyhydroxides at ultra-slow spreading centers remain poorly understood. This study focused on six Fe–Si oxyhydroxide deposits collected from different sites at a typical ultra-slow spreading center, the Southwest Indian Ridge (SWIR).

Deep-sea (deeper than 200 m) creatures are poorly understood taxa that live in high-pressure, dark, and cold environments. Here, we provide a high-quality genome assembly of a new deep-sea anemone species (Paraphelliactis xishaensis sp. nov.) living at a depth of 3230 m in the Xisha Trough in the South China Sea. Through comparative genomic analyses, we revealed molecular signatures of deep-sea environment

Lateral advection affects the spatial distribution of dissolved substances in the ocean but very few studies, so far, have been devoted to describe and quantify its impact on the distribution of dissolved organic carbon (DOC) which, in oligotrophic environments, accounts for the largest fraction of chemical energy. In this contribution, using an integrated approach, we explore the importance of surface

Protists are extremely diverse morphologically and physiologically, and they play important ecological roles at multiple trophic levels as primary producers and consumers in nearly all microbial communities. In spite of their fundamental importance in marine ecosystems, protistan diversity and distribution has yet to be comprehensively characterized in much of the world ocean, particularly in the vast

Topographic and hydrodynamic complexity in submarine canyons promotes steep gradients in food availability and geophysical parameters which affect ecological assemblages and beta diversity. While habitat heterogeneity in submarine canyons is known to support diverse and abundant megafaunal communities, due to difficulty in sampling little is known about infaunal communities adjacent to hard substrate

Ecological niche modelling is used in deep-sea research to investigate the environmental preferences and potential distribution of data-poor species. We present a mesoscale assessment of Mediterranean seascape suitability for the cold-water coral Lophelia pertusa (= Desmophyllum pertusum, Linnaeus, 1758). We estimated seascape suitability and uncertainty maps using an ensemble approach of three machine-learning