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

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 overflow 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)

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 that 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

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

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

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

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

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 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

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

This study compiles information on the size distribution and reproductive patterns of five chondrichthyans and 10 bony species dwelling on the continental slope of the Central-Western Mediterranean (south-eastern Sardinian waters, depth 720–1890 m). The abundance of the relatively less numerous chondrichthyans was found to decrease with depth. Almost all chondrichthyan species had a long reproductive

The deep ocean, one of the largest biomes on Earth, supports diverse microbial communities, which play important roles in biogeochemical cycles. However, despite their importance, viruses in the deep ocean remain largely unknown. In this study, we performed metagenomics to investigate viral communities from deep sea waters in the South China Sea (SCS) and western Pacific Ocean (WPO). Deep-sea viral

We investigated the feeding ecology of blue whiting (Micromesistius poutassou) in the NW Mediterranean living in two habitats, the shelf break and the continental slope, throughout the year, by combining two methodological approaches, stomach content characterization and stable isotope analyses. Stomach content indicated that blue whiting mainly fed on Myctophidae fish, decapods and euphausids. Differences

The presence of sperm storage was evaluated in several deep-sea elasmobranchs (Centrophorus squamosus, Centroselachus crepidater, Deania calcea, Brochiraja spinifera, Brochiraja asperula, Apristurus ampliceps, A. exsanguis, A. garricki and A. sinensis), all considered at risk to the impacts of fishing in New Zealand. Biological measurements of reproductive organs (e.g. follicle size and number, oviducal

Trematode sporocyst and rickettsia weighted prevalences were found to be extremely high in Gulf of Mexico petroleum seep mussels, Bathymodiolus childressi, in comparison to shallow-water mytilids. Understanding the role that parasites might play in mussel population dynamics and health requires an understanding of the rapidity with which parasite infections and physiological condition respond to changes

The bamboo coral Isidella elongata is a key structuring species on deep muddy bottoms, which has suffered severe consequences from bottom-fishing activities, as it often co-occurs with precious fishery resources such as red shrimps. A five-year series of data collected during a scientific trawl survey was used to localize the presence and to characterize the associated megafauna over a wide spatial

Water exchanges between the Tyrrhenian Sea and the Liguro-Provençal basin occur through the Corsica Channel, a narrow passage between Corsica and the Elba Island, near the Italian coast. It has long been known that the Channel hosts a robust Tyrrhenian outflow in winter, which penetrates far into the Ligurian Sea, reaching the site where deep-water formation takes place. The summer circulation in the

The surface connection between the Ionian Sea (central Mediterranean Sea) and the surrounding areas is studied by looking at the statistical properties of 1632 near-surface Lagrangian trajectories. The choice of the area is due to the key role in the dynamics of the Mediterranean Sea and to the geographical distribution of data. The Lagrangian drifter data were taken from the OGS Mediterranean drifter

Spring and summer Southern Ocean phytoplankton communities have been well characterized, but winter communities are often overlooked. Diatoms are a major contributor to Southern Ocean particulate organic carbon (POC) production and export, and exert a strong control on Antarctic surface and Subantarctic thermocline nutrient concentrations, thus influencing the low-latitude nutrient supply. Understanding

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

In this paper, two new species of the genus Rosalinda found growing on bivalves from West African cold-water coral mounds are described. Rosalinda nowaldi sp. nov. was found on Acesta angolensis (Adam & Knudsen, 1955) off northern Angola, and Rosalinda lundalvi sp. nov. on Acesta excavata (Fabricius, 1779) off Mauritania. Both new species have a similar cnidome, but they can be easily differentiated

Few studies examined species or ecosystem dynamics on seamounts/banks. The Galicia Bank (GB), the deepest marine Special Area of Conservation in the Spanish Natura 2000 network, is considered a conservation priority because of its highly vulnerable habitats, such as cold-water and bamboo corals. The biological conditions and population structure of benthopelagic shrimps and their relationship with

Kelp forest produce large amounts of macroalgal detritus, ranging from whole plants to small particles (1 mm). The role of this kelp detritus in fueling deep-sea communities adjacent to healthy kelp forests was investigated in a region in the North of Norway by comparing the community structure and biodiversity of meio-, macro-, and megafauna in two deep (450 m) areas with different expected input

Mesophotic coral reefs (~30–150 m) and deeper reefs (>150 m) represent some of the least explored and poorly documented habitats in our oceans. These deep ecosystems are both high in biodiversity and ecologically distinct from shallower reefs. They are also equally threatened by natural and anthropogenic factors. Thanks to advancements in remote undersea technologies, our access to and understanding

Pockmarks are circular-shaped depressions that increase seabed heterogeneity and are characterized by discontinuous fluid emissions. To understand how environmental conditions of pockmarks affect the structure of macro- and meiofauna, we investigated two sites in a pockmark field in the northwestern Madagascar margin. In a comparative approach, we explored the community structure of the dominant taxa

Connectivity is a fundamental process driving the persistence of marine populations and their adaptation potential in response to environmental change. In this study, we analysed the population genetics of two morphologically highly similar deep-sea sponge clades (Phakellia hirondellei and the ‘Topsentia-and-Petromica’ clade, (hereafter referred to as ‘TaP clade’)) at three locations in the Cantabrian

Grain size distributions are a key physical measurement in marine sediment studies. The introduction of laser diffraction spectrometry analyzers a few decades ago, allowed the differentiating of grain size in higher resolution than before, and led to increased volumes of samples analyzed overall. However, pretreatment of the sediment samples is required for obtaining high quality results by this method

We investigate the uppermost 60 cm of sediment in active pockmarks of a deep-water methane seep site from Vestnesa Ridge offshore NW Svalbard. Using video guided core sampling with a remotely operated vehicle we collected push cores directly from bacterial mats within two active pockmarks, Lunde and Lomvi. Pore water analyses show very shallow sulphate methane transition zones and transport-reaction

The influence of long, sub-inertial waves travelling poleward on spatiotemporal fluctuations in the hydrography of coastal upwelling areas has widely been discussed theoretically in the literature since the late 1970s. In this paper, in contrast, measured unexpected wave-like changes in the intermediate density field along the Namibian continental slope are presented and suggested to be the result

Marine life has been detected in the ocean's trenches at great depths, down to nearly 11 km. Such life is subject to particular environmental conditions of large static pressure exceeding 1000 atm. While current flows are expected to be slow, waters cannot be stagnant with a limited exchange of fresh nutrients needed to support life. For sufficient nutrient supply, the physical process of turbulent

Using a combination of data obtained from high-definition still images, video, and specimens collected during human-occupied submersible and remotely-operated vehicle dives spanning the period 2003 to 2014, we provide the first detailed characterization of the megabenthic assemblages in the lower bathyal on the New England and Corner Rise Seamounts in the Northwest Atlantic. Over all, the New England

Pelagic polychaetes collected in the deep Arctic Ocean between 2011 and 2016 during three expeditions of R/V Polarstern were investigated using morphological taxonomic and molecular methods based on DNA sequences for portions of the mitochondrial 16S and nuclear 18S and 28S rDNA genes. A comparison of our results on arctic Pelagobia cf. longicirrata Greeff, 1879, (Lopadorrhynchidae) and Typhloscolex

As part of the New Zealand government Ocean Survey 20/20 programme (OS 20/20, 2006–2013), samples from the Chatham Rise and Challenger Plateau collected in 2007 were analysed to determine the effects of key environmental parameters, in particular sediment and water mass properties, on spatial changes in the community structure (abundance, diversity and community composition) of bathyal asellotan isopods

This study explores the role of photosynthetically-derived carbon in seep communities at shallower, bathyal seeps and at deeper, abyssal seeps on the Barbados accretionary prism. Carbon sources and feeding guilds were assessed from five Barbados seeps and three putative non-seep sites through carbon and nitrogen stable isotope analyses on numerically-dominant and/or high-biomass species. Thiotrophy

Megabenthic assemblages in deep-sea sedimentary environments receive far less attention than those occurring on rocky environments, despite they have been widely impacted by destructive trawling activities, mainly due to their association with important commercial species. ROV dives conducted on bathyal muds of the Alboran Sea continental slope (western Mediterranean) were used to characterize megabenthic

We report on the first beluga whale (Delphinapterus leucas), an adult female, from the Eastern Chukchi Sea (ECS) stock to be tagged with a Satellite Relay Data Logger (SRDL) that included a miniaturized Conductivity, Temperature, and Depth (CTD) sensor capable of collecting temperature (T) and salinity (S) profiles as the beluga dove. Prior work speculated that ECS belugas may target fronts and stratified

SAR202 in Chloroflexi phylum plays an important role in degradation of organic compounds in the oligotrophic deep ocean. Due to lack of high-quality genomes from across all depths of the water column, the metabolic capacities of the SAR202 subclusters in the marine environment were still largely unknown. In this study, we discovered the dynamics of the SAR202 subclusters in vertical layers of global

The continuing exploration of the Mediterranean deep sea reveals that a complete census of the biodiversity of one of the most studied marine areas in the world is yet to be fully accomplished. A tritoniid nudibranch new to science is described upon material recovered off the Montenegro margin, Adriatic Sea, associated with the alcyonacean Primnoidae Callogorgia verticillata (Pallas, 1766). Here, a

Habitat differentiation is the essential force for shaping animal and plant biogeography. Distribution patterns of microeukaryotes, which are an assemblage of highly diverse and phylogenetically distant groups, across multiple marine habitats remain largely unknown. We hypothesize that microeukaryote communities vary across different types of marine habitats at the regional scale similar as macroorganisms

The thickness of oxygen minimum zone (OMZ) is estimated for the first time using dissolved oxygen (DO) profiles obtained from the Biogeochemical Argo floats collected between 2013 and 2019 in the Arabian Sea. The depth of upper boundary of the OMZ varied narrowly between 70 and 220 m in the entire Arabian Sea whereas the lower boundary of OMZ significantly deepened from south (500 m) to northern Arabian

The structure of the pelagic food web is a key issue to understand the variability in C and N fluxes in the ocean. The trophic structure of the hyperiid amphipods and its spatial variation in the subtropical area of the Southeast Pacific was studied based on C and N isotope composition. Zooplankton were collected off northern and Central-southern Chile during September-November 2016 at the coastal

The Zapiola Anticyclone (ZA) is a strong, O(100 Sv), barotropic vortex in the center of the Argentine Basin that is tied to a bathymetric feature called the Zapiola Rise. It is regionally significant for two reasons: first, the strong vortex is a dynamical barrier that inhibits the lateral exchange of water, and hence has the ability to trap water for a long period of time. Second, its dynamics is

Hadal trenches house distinct ecosystems but we know little about their sources of nutrition or trophic structures. We evaluated megafaunal food web structure and nutritional sources in the Kermadec and Mariana trenches using carbon and nitrogen stable isotope analysis (δ15N and δ13C values) of bulk tissues and proteinaceous individual amino acids (AAs). In the Kermadec Trench, bulk δ15N values ranged

Fish sounds are important components of Azorean soundscapes. Therefore, unraveling their patterns can contribute to a better assessment of local biodiversity dynamics. Passive Acoustic Monitoring (PAM) is a cost-effective, non-intrusive method providing long-term information regardless of weather or logistic conditions, which can be especially useful when monitoring remote areas. Using PAM, we assess

Larval fish have been shown to vertically migrate with ontogeny, a behaviour that influences their dispersal by exposing the larvae to currents with different velocities at different stages of development. Most studies have focused on studying the vertical migration of tropical reef fishes, that have been shown in general to migrate downwards with ontogeny. Here we investigated if similar ontogenetic

Bathymodiolus Kenk and Wilson, 1985 includes fourteen currently recognized species from deep-sea chemosynthetic environments in the Pacific, Atlantic, and Indian oceans. In this study, phylogenetic analyses of mytilid mussels sampled from seeps along the Costa Rica margin reveal the presence of three new Bathymodiolus species, sampled from depths across ~1000–1900 m. Bathymodiolus billschneideri n

During the North Atlantic Bloom Experiment (NABE) of the Joint Global Ocean Flux Study (JGOFS), water column sampling for particulate and dissolved 210Po and 210Pb was performed four times (26 April and 4, 20, 30 May 1989) during a month-long Lagrangian time-series occupation of the NABE site, as well as one-time samplings at stations during transit to and from the site. There are few prior studies

Recent advancements in deep-sea expeditions have made possible to sample adequate quantities of deep-sea organisms over wide geographical ranges for population genetic studies. Scalpellum stearnsii is a common stalked barnacle that occurs in the mesobenthic environment (>200 m depth) throughout the West Pacific Ocean and covers several major deep-sea basins. The present study examined the diversity