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 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

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 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

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

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 showed 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

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

The Mariana Trench in the western North Pacific (NP) contains the deepest (11,000 m) point in the ocean and thus remains the least explored environment. Carbon cycling in the deep Mariana Trench is largely unknown and remains a curious mystery. Here, we report radiocarbon (Δ14C) and stable carbon isotope (δ13C) compositions of dissolved inorganic and organic carbon (DIC and DOC) and sinking particulate

The pelagic cephalopods Japetella diaphana and Vampyroteuthis infernalis are charismatic and widely distributed members of deep pelagic ecosystems. Their habitat temperatures, metabolic rates, feeding and reproductive strategies all together suggest that the pace of life in these species is reduced when compared to neritic octopod species, but information on longevity, growth rates and age estimations

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

Using high-resolution measurements of the Gulf Stream North Wall (GSNW), we investigated whether detachments from the warm current at the edge of the front, known as streamers, affect the overall heat and salt content of the region. Temperature, salinity, and velocity data were collected across the front from towed CTDs, shipboard ADCPs, and gliders following a Lagrangian drifter that was deployed

Many foraging fishes spend their vulnerable life stages with low food availability in the oligotrophic Kuroshio. Although they are likely dependent on microbial production as their energy source, there is limited knowledge of the trophodynamics of the planktonic food web in the Kuroshio of the East China Sea (ECS-Kuroshio). Here, we demonstrate energy sources and feeding impacts of microzooplankton

Here we present the results from a shotgun sequencing effort on foot tissues from a deep-sea hydrothermal vent endemic limpet. We present the complete mitochondrial genome of the hydrothermal vent endemic gastropod Peltospira smaragdina (Gastropoda, Peltospiridae) for the first time. This species is characteristic of circa-Azores hydrothermal vent ecoregion and provides a candidate environmental DNA

Deep-sea coral communities are poorly known in the Southwestern Atlantic (SWA), particularly in the equatorial/subequatorial latitudes embraced by the northeastern Brazilian Exclusive Economic Zone (EEZ). Such knowledge gap has lead to the idea that the latter has low species richness when compared to southern Brazilian regions. Recent studies, however, indicate the northeastern slope as highly suitable

Bernasconiaster pipi gen. et sp. nov. is described from work carried out in deep waters off Argentina. It is a small species with six arms, which has only cross-type pedicellariae, among other particular characteristics. Some specimens were found brooding their offspring in the oral area with their arms arched. Up to seven different stages of development were observed, each located at a particular

Specialist fauna populations from chemosynthetic ecosystems are connected through larval stages travelling in current highways in the vast deep sea. One shrimp family of such specialists, Alvinocarididae, is hitherto known to be endemic to vents and seeps with no reported occurrence in ephemeral organic-rich chemosynthetic habitats. Here we report the first occurrence of Alvinocaris muricola on experimentally

The Mediterranean is a semi-enclosed sea, with a narrow natural connection —the Strait of Gibraltar— through its western basin to the North Atlantic. Many studies have investigated how the inflow of North Atlantic Surface water into the Mediterranean shapes the faunal composition and abundance of the shallow-water benthic communities of the Western Mediterranean. However, the reverse effect remains

Distinguishing regions based on the geographic distribution of both abiotic factors and living organisms is an old but still actual central issue for biogeographers. In the Southern Ocean, the few existing regionalization studies have been carried out either at very large scales or on the relatively small region around the Sub-Antarctic islands of Kerguelen and the Crozet archipelagos. However, regionalization

We present the results of a multi-platform investigation that utilizes tracer information provided by the 2011 release of radioisotopes from the Fukushima Dai-ichi Nuclear Power Plant to better understand the pathways, mixing and transport of mode waters formed in the North Pacific Ocean. The focus is on transition region mode waters and radiocesium (137Cs and 134Cs) observations obtained from the

Shifts in phenology – annually occurring life history events – have been observed among many marine organisms due to global warming. We examined if phenological changes in the pteropod (pelagic snail) Limacina helicina antarctica have occurred along the Western Antarctic Peninsula, one of the most intensely warming regions on Earth, which would have important implications for regional food web dynamics

The first direct observations of the diversity and density of benthic epifauna from hadal depths was reported in 1965 from depths of 7300 m in the Puerto Rico Trench. The most striking part of the report from was an account of observing 200 snailfish (Liparidae) during a one mile transect by the bathyscaphe Archimède - an extraordinarily high-density of fish for hadal depths. In 2019 the submersible

Hydrocarbon seepage in cold seeps provides an appropriate environment for chemosynthetic communities to arise and for authigenic carbonates to form. To study the relationships between the chemosynthetic communities and underlying authigenic carbonates, extensive in situ Raman measurements were conducted on the fluids, chemosynthetic communities, and authigenic carbonates found at the Formosa Ridge

We found that the Hu et al. model for light scattering by pure seawater [Deep Sea Research Part I, 146, 103–109 (2019)] can be applied to waters with sub-zero temperature, which was outside the applicable range of the original equation for the refractive index of water that is used in the model. The surface waters with temperature < −1 °C in the Arctic Ocean and surrounding the Antarctic exhibit the

Argo float trajectory data has been used to estimate the velocities of mid-depth (1000 db) currents in the North Indian Ocean (NIO). The structure of the upper ocean absolute geostrophic currents can be derived more accurately from the Argo temperature and salinity profiles by referring to the estimated velocities rather than by assuming a level of “no motion”. The derived flow field reveals that the

We examined the distribution and feeding habits of the diel vertical migratory myctophid Myctophum orientale in the Kuroshio region of the western North Pacific in late winter. All 1985 specimens collected were in the juvenile stage, with a mean standard length (SL) of 29.9 mm. They occurred on the onshore side of the Kuroshio axis along the slope region off Japan, showing a typical pseudoceanic distribution

While reproduction in deep-sea corals remains incompletely understood, there is a particularly crucial shortage of information related to corals living in deep waters of the Arctic Ocean. In the present study, colonies of the deep-sea pennatulacean coral Umbellula encrinus were collected in Baffin Bay (High Canadian Arctic) at bathyal depths between 2006 and 2010. From examination of gamete sizes,

Intraspecific genetic differentiation reflects processes that underpin biodiversity in deep-sea habitats. We examined the spatial genetic structure of epibenthic amphipod taxa from upper bathyal depths (200–1200 m) along New Zealand's continental margins. Genetic variability in amphipods was assessed using cytochrome c oxidase I (COI) to characterise inter-regional diversity and phylogeographic patterns

Zooplankton diel vertical migration (DVM) during summer in the polar oceans is presumed to be dampened due to near continuous daylight. We analyzed zooplankton diel vertical distribution patterns in a wide range of taxa along the Western Antarctic Peninsula (WAP) to assess if DVM occurs, and if so, what environmental controls modulate DVM in the austral summer. Zooplankton were collected during January

The Western Isoguchi Jet, a quasi-stationary baroclinic jet that separates from the Kuroshio Extension, has been detected for a decade. Here we report the first observations of the vertical structure and temporal variations of the jet via moored current meters (September 2011–September 2012) and intensive hydrographic measurements (September 2010, 2011, and 2012). The jet flows northeastward and supplies

Deep-sea ecosystems are highly sensitive to changes in organic matter export and oxygenation driven by climate change. Here we document past ecological changes in benthic foraminiferal assemblages indicative of deglacial changes in deep-sea oxygenation and the character of organic matter fluxes from sedimentary records retrieved at intermediate (692 m) and abyssal (3667m) depths in the Gulf of Alaska

Food availability is a primary factor determining species distribution and success, especially for offshore benthic organisms that rely on sinking particles as their main food supply. Temporal changes in the quantity and quality of food sources, often linked to shifts in the prevailing hydrographic conditions, thus have important consequences for benthic community composition and ecosystem functioning

Cold-water corals (CWC) are known to be deep-sea biodiversity hotspots, yet there is still a huge knowledge gap regarding their associated fauna. As so, CWC ecosystems pose as a perfect environment for the discovery of new species. In this context two new species of Hamigera (Demospongiae) have been recorded associated with CWC in antipodal parts of the world: Hamigera bibiloniae sp. nov. from the

Sea-level fluctuations exert a major influence on deep-water depositional processes through changing sediment supply and oceanographic processes. By utilizing the bathymetric map and six piston cores (P1 and P5–P9) from the two major canyon systems (i.e., Pearl River Canyon (PRC) and Shenhu Submarine Canyon Group (SSCG)) within the Baiyun Sag, northern South China Sea (SCS), this study investigated

We examined primary production (PP) and the assimilation rates of nitrate (ρNO3-), ammonium (ρNH4+) and dinitrogen (ρN2) using 13C and 15N tracer techniques along bay to offshore transects in the Oyashio-Kuroshio-Tsugaru Warm Current interfrontal region in the northwestern North Pacific Ocean, during five research cruises covering a full seasonal cycle. Surface inorganic N was depleted in the bays

The bathypelagic zone is a large, dark, cold, high-pressure environment that undergoes extensive material and energy exchanges with the upper ocean and the deep biosphere. Viruses are important parts of the deep ocean, and transportation of surface viruses has been considered as an important source of deep-sea viruses. However, limited information is available about the activity and decay of surface

Embryonic development is a vulnerable and key period during the life cycle of an oviparous elasmobranch. Captivity studies are difficult to carry out on non-coastal species; hence, embryonic development can be analysed from samples collected from the seabed. Here, embryonic development of three shelf and deep-water skates from the southwest Atlantic Ocean, Bathyraja brachyurops, B. macloviana and Amblyraja

Submarine turbidity currents are one of the most important sediment transfer processes on earth. Yet the fundamental nature of turbidity currents is still debated; especially whether they are entirely dilute and turbulent, or a thin and dense basal layer drives the flow. This major knowledge gap is mainly due to a near-complete lack of direct measurements of sediment concentration within active submarine