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

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

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

Food availability in fjords is unusual among deep-sea environments (defined here as systems below 200 m) 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

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

Foraminifera are unicellular protists and play a major role in the deep-sea ecosystems. This study focusses on the faunal analysis of living benthic foraminiferal assemblages and their vertical distribution along a transect in the Rockall Trough in the NE Atlantic. Therefore, seven multicorer cores from the Rockall Trough (RT-1 – RT-7), NE Atlantic, were collected at water depths between 1008 and 2205 m

Spatial distribution patterns of protists in the deep sea are not yet understood and due to the remoteness of the deep-sea biome this is a challenging task. Here, we investigated the structure and dispersal of protist communities in abyssal sediments at three sites in the Caribbean Sea (15°53.21′N/68°55.73′W), the northwestern Atlantic (23°33.23′N/48°05.04′W) and the central Atlantic Ocean (10°20.38′N/36°57

In the South Pacific Ocean, upper and lower Circumpolar Deep Water (UCDW and LCDW, respectively) occupy the deep layers; however, the presence and fate of both these water masses in the western equatorial Pacific have been mostly based on sparse measurements in both space and time. In this study, unprecedented deep measurements from three cruises conducted in the Solomon Sea region along with the World

The sperm whale is the largest toothed whale that feeds almost exclusively on oceanic cephalopods. Since it was actively hunted commercially, considerably more is known about its food than for many other large marine apex predators. However, the use of those unique dietary information is today hampered by out-of-date cephalopod taxonomy. Here, the names of cephalopod prey of sperm whales were revisited

Interdecadal variations of the Western Subarctic Gyre (WSAG) in the North Pacific were examined mainly by analysis of absolute dynamic topography (ADT) during 1993–2017. The ADT was based on altimetry-derived sea level anomalies superimposed on state-of-the-art mean dynamic topography. We specified geostrophic surface streamlines of the WSAG associated with closed isolines of the ADT. The WSAG intensity

Environmental controls affecting the composition and distribution of deep sea benthic foraminifera were analyzed in the Panama Basin (Eastern Equatorial Pacific). For this study, results of the analysis of a new set of 33 core-top samples from the upper-lower slope (714–3819 mbsf) were integrated with previous data from this area. The composition of the foraminiferal assemblages resembles a typical

The present study represents the first documentation of the trophic spectrum of the deep-water bony fish Pagellus bogaraveo in two different habitats in the central Mediterranean Sea: muddy bottoms (MB) and cold-water coral (CWC) habitats. A total of 133 stomachs were collected on MB and 39 in CWC habitats. The feeding habit of P. bogaraveo was different in the two investigated habitats. A lower number

Hagfishes, the most ancient jawless fishes, have a pivotal biological status. Gut bacterial communities are considered to be another organ that supports host survival and reproduction, while most gut microbiota cannot be cultured in vitro. In this study, four deep-sea hagfish individuals were collected from the South China Sea (>900 m). 16S rRNA and metagenomics approaches were used to analyze the

A seasonal study of the life cycle and reproductive biology of the copepod Calanus finmarchicus – the dominant zooplankton species and a key link between the lower and higher trophic levels within the southwestern Norwegian Sea - is presented. C. finmarchicus reproduces, feeds and accumulates lipids during spring and summer within surface waters, which enables it to survive overwintering at depth until

IODP Ex. 323 shipboard rock magnetic measurements of Quaternary deep-sea sediments from the Bering Sea identified a dramatic bimodal character to the sediments, alternating between sediments with strong natural magnetic remanence (NRM) and magnetic susceptibility (chi) and those with order-of-magnitude lower values. We now generally associate the high-magnetic-intensity sediments with interglacial/interstadial

Pockmarks are crater-like depressions in seabed sediments commonly found along continental margins and generally associated with episodic fluid seepage. In this study, we describe a new species of Chloeia (Amphinomidae) gathered from a pockmark field, located off the southeastern Brazilian continental margin (∼750 m depth), SW Atlantic. The complete mitochondrial genome is given, together with a multi-gene

Biophysical interactions of the mesopelagic fauna and hydrodynamic features were investigated at a shallow, tall seamount in the tropical Northeast Atlantic based on data from three inter-disciplinary surveys collected between 2009 and 2015. Senghor Seamount is located close to the equator in a unique but underexplored oceanographic setting, where classical seamount effects are expected to be small

Many biodiversity patterns across the globe can be partially explained by energetics and habitat structure, including in the deep sea. Because of difficulties in logistics, studies focusing on deep-sea benthic systems often have limited sample sets that may be far apart in space. Here, we present analyses based on a well-sampled region, the northwest Atlantic, allowing us to relate patterns of polychaete

Deep-sea environments in the Mediterranean Sea have been widely degraded over the past decades and thus there is an urgent need to implement protection measures. Within European Union's Mediterranean waters vast extensions of the deep-sea ecologically relevant ecosystems have been protected by integrating them to the Natura 2000 network. Inside the French Exclusive Economic Zone, this network is currently

The external geometry, internal architecture and sedimentary evolution processes of the deep-water channel system in Zhujiang Formation in the Midwest of Baiyun Sag have been revealed in detail according to the integrated analysis of 3D seismic data and a large number of drilling and logging data sets. In addition, the controlling effect of sediment supply, sea level change, shelf break zone and palaeogeomorphology

Despite nutrients supply through river discharge, atmospheric deposition and eddy-driven mixing, low primary production in the Bay of Bengal (BoB) is attributed to light limitation and non-availability of nutrients during summer monsoon. We report here the first ever measurements of release of significant fraction of primary production as dissolved organic carbon (DOC) in the BoB through isotopic tracer

This study presents a broad-scale view of larval fish species distributions in the eastern Central and North Atlantic and places it in a hydrographic context. Pelagic fish larvae, including metamorphic stages, were sampled to 1000 m depth across a 46° latitudinal transect from the equator to the Bay of Biscay. By analysing species composition and relating it to hydrographic parameters, we were able

The present investigation focuses on the Global Sea Mineral Resources contract area B4S03 site in the Clarion-Clipperton Fracture Zone nodule fields. We investigated the sedimentary characteristics and the higher-taxon (order/class) and lower-taxon (family, morphospecies) diversity of the soft sediment macrobenthos with special focus on the dominant taxa (Isopoda, Polychaeta, Tanaidacea) in relation

A flow cytometric analysis of picoplankton (Prochlorococcus (Pro), Synechococcus (Syn), picoeukaryotes (Peuk) and heterotrophic bacteria (Hbac) was performed along a meridional transect (88°E, 10°S – 4°N) in the eastern equatorial Indian Ocean (EEIO) during the boreal fall intermonsoon period. The transect spanned contrasting physical and chemical conditions, allowing investigation of the effects of

The diagenetic interplays of organic carbon (OC), sulfur (S), and iron (Fe) in marine sediments and their responses to changes in depositional and climatic conditions are poorly characterized. In this study, chemical speciation and isotopes were combined to characterize diagenesis of OC, S and Fe in sediments of the middle Okinawa Trough (OT), a back-arc deep basin along the edge of the East China

The abyssal seafloor makes up three quarters of the ocean floor, and it is generally characterized as a food-limited habitat with low numbers of megafauna, particularly fishes. Baited camera observations from three abyssal seamount summits in the equatorial Pacific challenge this idea. On each of two deployments at the southernmost seamount, over 100 synaphobranchid eels (Ilyophis arx) were recorded

Measurements made by deep floats had a salinity bias with a negative pressure dependency. Salinity is affected by conductivity measurements via changes in the CTD measuring cell geometry under pressure. To remove the effect, a canceling factor for pressure CPcor is prepared theoretically by the manufacturer considering the isotropic deformation of a single-cylinder measuring cell under pressure; the

Submarine canyons are peculiar habitats of the continental margin due to their hydrodynamic and geomorphological features. Coral assemblages forming marine animal forests (MAFs) are one of the key benthic components dwelling in these habitats, where they enhance the substrate's heterogeneity and provide shelter, feeding and spawning habitats for a wide variety of species. They are also considered Vulnerable

This study addresses the hydrodynamics inferred from the expendable conductivity-temperature-depth (XCTD) observations carried out in the southwestern Indian Ocean sector of the Southern Ocean along two transects: the Lazarev Sea to Cape Town (track-1) and Cape Town to Prydz bay (track-2) during the austral summer of 2019. The vertical temperature and salinity structures revealed an eddy extending

Since their first discovery, predictions of the incidence of high temperature submarine vents has been made from along-axis surveys for the presence or absence of particle-rich “black smoker” hydrothermal plumes in the overlying water column. Recent work along intermediate and fast spreading ridges, however, has shown that abundant lower-temperature forms of seafloor fluid flow might be overlooked

Overflows through oceanic gateways govern the exchange of water masses in the world's ocean basins. These exchanges also involve energy, salinity, nutrients, and carbon. As such, the physical features that control overflows can exert a strong influence on regional and global climate. Here, we present the first description of sedimentary processes generated by the overflow of Pacific Deep Water (OPDW)

The Variability of chlorophyll-specific phytoplankton light absorption [a*ph (λ)] was examined over depth and time in stratified offshore waters of the North-Western Mediterranean Sea. Coherent water patches were tracked with Lagrangian drifters during two oceanographic cruises in September (late summer) and May (post-spring bloom phase). By simultaneously analysing the phytoplankton absorption and

Gazul is the shallowest mud volcano (MV) within the Shallow Field of Fluid Expulsion (SFFE) of the northeastern Gulf of Cádiz (NE Atlantic; 300–1200 m depth). The SFFE represents an important geo- and biodiversity area that was designated as a Site of Community Importance under the European Habitats Directive in 2014. In this study, geological features, habitats and associated biodiversity, as well

Knowledge regarding the benthic community structure (macro- and meiofauna) and its production is crucial for understanding the consequences of ongoing climate change, yet it is still limited, particularly concerning springtime. This is the first study to provide information on the community characteristics and secondary production of macro- and meiofauna collected in the European sector of the Arctic

The Chatham Rise supports some of New Zealand's most economically valuable commercial fish stocks, fuelled by the highly productive waters of the Subtropical Frontal Zone (STFZ). Climate change-related shifts in phytoplankton community structure and function are predicted and may affect Chatham Rise productivity and deep-sea carbon sequestration by the biological carbon pump. However, little is known

Pacific bluefin tuna (Thunnus orientalis, PBF) is an economically important species, however, the population size has decreased for decades due to overexploitation. PBF has multiple spawning grounds and shows trans-Pacific migration for forage and reproduction. Therefore, a comprehensive understanding of the population connectivity and mixing rates among feeding and spawning grounds are required for

The population size structure, vertical distribution, gonad maturation, individual fecundity and embryonic development of the chaetognath Eukrohnia hamata were studied in the northernmost part of its distribution area, the Arctic Ocean. Analysis was based on stratified zooplankton samples collected in the Canada Basin during July 2005 that covered the depth range from the surface down to the bottom

Although many deep-sea species are considered to have transoceanic distribution, this assumption has rarely been critically tested. Using Hesiolyra (Hesionidae) as a case study, we show that careful molecular and morphological analyses are required for refuting/accepting claims about such wide distribution. Hesiolyra is a genus of polychaetes commonly found in hydrothermal vents of the Eastern Pacific