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Little information has been added to our knowledge of Panama’s Pacific coast seabirds since the last century. In order to increase and update our knowledge, systematic observations were made of seabirds on a total of 20 trips, conducted in 2010, then every year from 2012-2019 off the Pacific coast of Panama, and the percentage of all 1-hour observation periods during which each species was recorded according to location (continental shelf or continental slope/deep waters) and season (dry or wet) was calculated. Thirthy-nine species of seabirds of 11 different families during 120 1-hour observation periods were recorded. The most frequently detected species for all observations was Fregata magnificens (present in 65.8% of 1-hour observation periods), followed by Sula leucogaster (64.2%) and Chlidonias niger (63.3%). These observations increase our knowledge of seabird species occurring off the Pacific coast of Panama, adding three new species to the list of birds of Panama, and documenting another two with photographs for the first time, offering us an idea of the species that are within the reach of the pelagic avitourist.

Floating breakwaters have recently been generating increasing interest as a vital means to provide shelter and protect the ever-increasing number of structures deployed at sea. Notwithstanding the novel ideas being put forward, to date, floating breakwater deployment has been limited to inshore and shallow water areas. The scale of such structures has been restricted to the smaller spectrum. Furthermore, whilst some concepts to integrate floating breakwaters with other offshore systems have been proposed to benefit from cost-sharing strategies, studies related to floating breakwaters integrating energy storage are lacking in the open literature. The present research investigates the wave attenuating and dynamic performance of a large-scale floating breakwater in deep seas with a hydro-pneumatic energy storage system also integrated within the structure. This article highlights the arising need for floating breakwaters and sheds light on the present-day technological status of floating wave breakers. It then lays the ground for the proposed, novel floating breakwater concept that aims to address the current knowledge gaps in this field of study. The simulation results generated from numerical modelling via the potential flow solver ANSYS® AQWA™ have been promising, connoting that the addition of hydro-pneumatic energy storage to a floating breakwater will not lead to a degradation in the dynamic performance or wave breaking efficiency of the floating structure. [ABSTRACT FROM AUTHOR]

Spatiotemporal information is crucial for cetacean research and conservation, particularly for wide-ranging and migratory species. Sperm whales (Physeter macrocephalus) are distributed worldwide in deep oceans; however, little is known about the species in the western margin of the Pacific Ocean. Here, we examined the available information related to the occurrence, distribution, and potential habitats of sperm whales in the waters off China. Historical whaling information (18th-20th century) indicates that sperm whales have been captured in the East China Sea (ECS) and South China Sea (SCS). Furthermore, sporadic strandings have been recorded since the 1910s, and more frequently from 1990 onwards. Since 1990, accidental sightings have been documented in the eastern ECS, northeastern and southern SCS, and their adjacent waters. More recently (2019-2022), field encounters have been reported in dedicated ship-based investigations in the Xisha and Nansha waters, providing robust evidence of the regular existence and potential residency of sperm whales in the northwestern and central areas of the SCS. Female nursery groups suggest that the Xisha waters might be an important nursing ground for sperm whales. Satellite tracking data from four adults showed that sperm whales in the SCS might display both fine-scale and long-distance movements. Taken together, it appears that sperm whales are currently active in the waters off China, and that deep waters (depth >200 m) in the ECS and SCS may provide the species with critical habitats. This review provides crucial baseline information on sperm whales in the waters off China, which may help to facilitate future research efforts and conservation initiatives for the species at national and cross-regional scales. More field investigations and other monitoring approaches including acoustic monitoring, biologging, photo-identification, and genetics are required to reveal the distribution, movement, and habitat use patterns of sperm whales in these waters. [ABSTRACT FROM AUTHOR]

Floating breakwaters have recently been generating increasing interest as a vital means to provide shelter and protect the ever-increasing number of structures deployed at sea. Notwithstanding the novel ideas being put forward, to date, floating breakwater deployment has been limited to inshore and shallow water areas. The scale of such structures has been restricted to the smaller spectrum. Furthermore, whilst some concepts to integrate floating breakwaters with other offshore systems have been proposed to benefit from cost-sharing strategies, studies related to floating breakwaters integrating energy storage are lacking in the open literature. The present research investigates the wave attenuating and dynamic performance of a large-scale floating breakwater in deep seas with a hydro-pneumatic energy storage system also integrated within the structure. This article highlights the arising need for floating breakwaters and sheds light on the present-day technological status of floating wave breakers. It then lays the ground for the proposed, novel floating breakwater concept that aims to address the current knowledge gaps in this field of study. The simulation results generated from numerical modelling via the potential flow solver ANSYS® AQWA™ have been promising, connoting that the addition of hydro-pneumatic energy storage to a floating breakwater will not lead to a degradation in the dynamic performance or wave breaking efficiency of the floating structure.

Deep ocean regeneration of dissolved silica (DSi) is an essential part of the ocean silica cycle and is driven by a complex series of biogeochemical processes. Here we compare the distributions of DSi and other environmental parameters in several western Pacific marginal seas to explore the role of marginal seas in deep ocean DSi regeneration. Results show that in oligotrophic marginal seas (such as the South China Sea), the DSi content in deep waters is similar to that of the adjacent Pacific waters. However, in productive marginal seas (such as the Bering Sea), the DSi content in deep waters is markedly higher than that in adjacent Pacific waters at the same depths. This is mainly due to deep ocean DSi regeneration in the marginal sea basin, which is fueled by the high biogenic particle flux from the productive surface waters. On a global scale, deep ocean DSi regeneration is accelerated in productive marginal seas, causing marginal seas such as the Bering Sea to have the highest DSi concentrations of all global waters.

A specimen of Physiculus dalwigki Kaup, 1758 measuring 218 mm in total length, 190 mm in standard length, and weighing 90 g was caught off the northern Tunisian coast. This capture constitutes the first record of this fish from the Tunisian coast. The specimen is described including morphological measurements, meristic counts, and color. Due to a lack of records, the real status of the species in the Tunisian waters still remains questionable. Physiculus dalwigki occurs only off northern Spain and south to the Strait of Gibraltar in the waters surrounding Madera and the Azores Islands, and in the Mediterranean Sea from Nice (southern France) to the Tunisian coast. Therefore, it appears that P. dalwigki is displaying a disjoint distribution with the exclusion of a large western region of the Mediterranean Sea. [ABSTRACT FROM AUTHOR]

In this study, we analyzed the main distributional features of Scolecitrichidae species in the Southwestern Atlantic Ocean (northern region of Rio de Janeiro State) and determined and described their habitat partitioning, based on a night series of stratified samplings down to a depth of 1,200 m. A total of 18 species from seven genera were identified and grouped according to their depth distribution. Distinct vertical patterns of total density, richness, diversity, and evenness were observed, with a decrease in density and an increase in diversity and richness with increasing depth. The total scolecitrichid abundance was dominated by a few epipelagic migrant species (Scolecithrix danae, Scolecithricella minor, Amallothrix tenuiserrata, and Lophothrix frontalis). The nondominant species were distributed in different habitats in the mesopelagic layer (upper-mesopelagic, mesopelagic, and lower-mesopelagic species) according to their vertical patterns of abundance and occurrence in the two sampling periods (rainy and dry season). The total density of scolecitrichid copepods was positively related to temperature and nitrate, and negatively related to silicate at 1 m depth. The abundance of scolecitrichids copepods in the upper layer with warm and oligotrophic waters supports the hypothesis of the influence of different water masses on the scolecitrichid assemblage. High abundance of appendicularians (Oikopleura longicauda) at 1 m depth in the region implies a high production rate of discarded “houses”, an important dietary component for Scolecitrichidae copepods. The observed patterns of seasonal cycles and vertical distribution suggest that the diverse scolecitrichid assemblage in the region may be structured mainly according to the partitioning of vertical habitats and food resources.

Long-term variability of the concentrations of oxygen and hydrogen sulfide in deep waters of the Gdansk Basin of the Baltic Sea for the last 25 years was considered. The dependence of suboxic and anoxic conditions in deep waters on the intensity and periodicity of the inflow events of the North Sea waters was shown. During the years of 1993, 2003, and 2014–2016, three intervals of strong increase of the concentration of dissolved oxygen after Major Baltic Inflow events (MBI) were distinguished. It was shown that the near-bottom layer of the Gdansk basin was aerated during two or three months after MBI in January–March whereas the two-year absence of MBI resulted in the appearance of hydrogen sulfide. However, the most pronounced hydrosulfide contamination within the period of surveys was registered in the middle and late 1990s, with as high hydrogen sulfide concentrations as 2.8 mL/L. A quality of reanalyzing the distribution of dissolved oxygen was evaluated as well. One may note a good repeatability of the field data by reanalysis of SHMI in terms of quality; however, the observed maximum concentrations in the distribution of dissolved oxygen were underestimated, sometimes even several times. [ABSTRACT FROM AUTHOR]

We report dissolved concentrations of the long-lived radioisotope 236U measured in the water column along the 2013 US GEOTRACES Eastern Pacific Zonal Transect (GP16). This transect followed a 10–15°S line from Manta, Ecuador, to Papeete, Haiti, French Polynesia, crossing the southern East Pacific Rise, intercepting one of the largest hydrothermal plumes as well as a productivity gradient, which includes the upwelling zone and associated low oxygen waters offshore from Peru and the oligotrophic sub-tropical gyre. Accelerator Mass Spectrometry was used to measure dissolved seawater 236U concentrations as low as 1 × 103 atom kg−1, which are among the lowest levels reported to date. Differences in upper water column 236U distributions from east to west are a result of variable contributions from different surface and intermediate waters encountered along the transect. The distribution of 236U, both in depth and geographically, provides complementary information to that obtained from Δ14C and helium isotopes, demonstrating that 236U concentrations are diagnostic in the identification of and contributions from the different deep and bottom water masses encountered along the EPZT (Jenkins et al., 2017). For example, we observe minimum 236U concentrations along the EPZT between 2000 and 3000 m that are consistent with contributions attributed to Pacific Deep Water. We also observe increases in 236U below 3000 m at the eastern and western termini of the EPZT. This is consistent with contributions associated with Antarctic Bottom Water and Lower Circumpolar Deep Water. Our results indicate that 236U may be used in conjunction with Δ14C and 3He isotopes as an additional tool with which to identify and resolve contributions from different water masses in the Pacific Ocean. This article is part of a special issue entitled: "Cycles of trace elements and isotopes in the ocean – GEOTRACES and beyond" - edited by Tim M. Conway, Tristan Horner, Yves Plancherel, and Aridane G. González. Unlabelled Image • 236U inventory in EPZT is one order of magnitude lower than in North Pacific. • 236U anthropogenic contribution at the EPZT is due to global fallout contribution. • AMS was used to measure dissolved 236U concentrations, which are among the lowest 236U values reported for seawater. • Lowest 236U concentrations were 1 × 103 at kg−1, measured between 2000 and 3000 m. • 236U distributions were used to identify deep and bottom water masses in EPZT. [ABSTRACT FROM AUTHOR]

Previous work on deep-water bryozoans in the North Atlantic have focused mainly on the northeast Atlantic, and only a few, earlier papers examined the bryozoans from deep water close to the Azores Islands. This is the first report on cheilostome bryozoans from the Mid-Atlantic ridge. The remotely operated vehicle (ROV) LUSO was used to collect samples during the campaign EMEPC/PEPC/LUSO2016. Bryozoan specimens were collected from nine sampling points distributed on two localities along the Hayes Fracture zone of the Mid-Atlantic ridge. These localities are between 1072 m and 1474 m deep and represent two habitats types: rocky bottoms and detritic bottoms. Abiotic data (depth, temperature, salinity, O 2 saturation, mg/l of O 2 compensated by salinity and pressure, turbidity and fluorescence) were collected to characterize the sampling points. Fifteen species of bryozoans were identified, of which seven are described for the first time and three remain in open nomenclature but probably also involve unknown species. This represents more than 50% of the unknown species, which is similar to data from other deep-water areas such as seamounts. Biogeographically, closer affinities were determined with species from the North Atlantic, but genera from the South Atlantic or with stronger Pacific affinities were also found. Two different communities were detected but they were not dependent on the habitat type. We attribute this to the stability of and low sedimentation at these deep-water detritic bottoms. Positive correlations between these species assemblages and abiotic variables were found only for depth, temperature, O 2 saturation and mg/l of O 2. Nonetheless, only temperature and depth apparently influence community type, although, as in previous studies on other faunas from the Mid-Atlantic ridge, other variables not considered here could have influenced bryozoan distribution. • Cheilostomata diversity is studied for first time in the Hayes Fracture, in the Mid-Atlantic ridges. • Fifteen species of Cheilostomata (Bryozoa) are recorded from Hayes Fracture, with the description of seven new species. • More than the 50% of the found diversity was unknown until now, similar data to other deep waters habitats as seamounts. • Communities were found not dependent of the habitat type, but with positive correlation with the temperature and depth. [ABSTRACT FROM AUTHOR]

Since the beginning of the 1980s, deep convection has ceased in the Greenland Sea. The effects of this halt on the intense warming and salinification of Greenland Sea deep waters and on the "dome collapse" (sinking of the dome) have been intensively studied. However, their causes and the potential outflow of Greenland Sea deep and bottom waters toward southern adjacent basins have remained less investigated and are the focus of this work. Combining oceanic and atmospheric in situ data, together with satellite and reanalysis data, it is found that there is not a unique factor responsible for the halt of deep convection in the Greenland Sea. Changes in the Ekman pumping seem to only explain one tenth of the observed deepening of isopycnals of 1,300 m in the central Greenland Sea (dome collapse). Since the early 1980s, in addition, a decrease in the mean net heat loss from the ocean to the atmosphere and in the intensity and number of intense heat loss events would have contributed to the decrease in both the intensity of convective mixing and the generation of dense deep waters. The generation of waters not sufficiently dense to contribute to the reservoir of water below the Greenland Sea dome would have led to its emptying and sinking. More importantly, it is found that in situ evidence of a sustained bottom‐water upwelling driven by a secondary circulation cell whose major role in ventilating and draining the Greenland Sea deep and bottom waters has been largely underestimated. Plain Language Summary: The Arctic Mediterranean shows one of the highest sensitivities to recent climate change, as the sea ice retreat or surface temperature increase reflects. However, although less known, these changes extend to the deep waters of the Arctic that are warming in the Greenland Sea at a rate 10 times higher than the temperature increase in the global ocean on average. These changes are the result of halt of deep convection in the Greenland Sea since the early 1980s. Based primarily on observations, the present manuscript investigates the causes for the halt of deep convection in the Greenland Sea. Its is found that changes in air‐sea exchanges and preconditioning have been mostly responsible for the halt of deep convection. More importantly, it is also noticed that the halt of deep convection may be nondetermining in the ventilation of Greenland Sea deep waters since a sustained bottom‐water upwelling seems to occur. These results are not only of crucial importance for the Greenland Sea. They are another indication that the mechanism that drives deep water ventilation may be not related to the "push" of dense waters to great depths but with the "pull" of mixing those waters upward and into the surrounding boundary currents. Key Points: Changes in air‐sea exchanges and preconditioning have been mostly responsible for the halt of deep convectionSurprisingly, the halt of deep convection may be nondetermining in the ventilation of Greenland Sea deep watersA sustained bottom‐water upwelling may ventilate and provide an exit for Greenland Sea deep waters toward southern adjacent basins [ABSTRACT FROM AUTHOR]

• State-of-the-art and historical development of composite risers for deep waters. • Research findings on composite risers from detailed bibliographic review. • Overview on composite riser assessment based on structural and mechanical behaviour. • End-fitting designs, and stress profile from load responses on composite risers and end-fitting. • Marine industry application of marine riser configurations, like SLHR for composite risers. The need for the utilisation of marine risers in deep seas has increased in recent years and this is due to increased drilling explorations with the shift in trend from shallower to deep and deeper waters. Also, there have been increased applications in sea-crossing infrastructure resulting in the need for longer risers, leading to a significant weight increase of marine risers used. Composite materials can thus be utilised in marine riser engineering to provide lightweight, fatigue-resistant, corrosion-resistant, low-bending stiffness and high-strength characteristics. In this paper, the history and potential of composite marine risers, including the first successful deployment of a composite riser joint offshore on the Heidrun Platform in 1995, are reviewed. The paper also discusses the advances achieved on composite marine risers for deep waters and presents some recommendations on their use, in light of their current significance and growth. [ABSTRACT FROM AUTHOR]

The diversity and distribution of marine macroalgae along the Brazilian coast have been investigated in detail. However, information about the deep-water macroalgal flora remains scarce, available mostly in scattered publications or gray literature. In this context, the aim of this study was to describe three specimens of Rhodophyta (Cottoniella fusiformis, Frikkiella searlesii and Branchioglossum cf. minutum) collected in the deep waters of the continental shelf off the coast of the state of Espírito Santo during expeditions of the program Evaluating the Potential of Living Resources in the Exclusive Economic Zone. The morphology and distribution of the collected species are detailed, and the taxonomic and biogeographic implications are discussed.

In this paper, we tested the hydrodynamic characteristics of a new, double-winged otter board that consists of a forewing, a leading edge slat and a trailing edge flap. Flume experiments were conducted in a circulating flume tank by using a model with an aspect ratio (AR) of 0.85 and a horizontal planform area (S) of 0.09 m2. The results indicated that the critical angle (αcr) of the model was 44°, whereas the maximum lift coefficient (CLmax) was up to 1.715, and the door efficiency (K) was 1.122. The attack angle (α) ranged from 30° to 48° and from 10° to 46° when the lift coefficient (CL) and door efficiency (K) were greater than 1.2 and 1.0, respectively. To compare the difference between double-winged otter board and traditional Morgere Polyvalent Ovale, same model of Morgere Polyvalent Ovale was also tested under the same experimental conditions. The critical angle (αcr) and maximum of lift coefficient (CLmax) of the doublewinged otter board were 37.5% and 14.6% larger than those of the Morgere Polyvalent Ovale. Therefore, we concluded that the novel, double-winged otter board was more suitable for bottom trawling fisheries in the deep water of the Mauretania Sea due to its better hydrodynamic characteristics and stability. [ABSTRACT FROM AUTHOR]

A new species of deep-water barnacle belonging to the family Scalpellidae is described from the western central Pacific. Based on the presence and absence of radial stripes on the surfaces of the plates, the 23 species of the genus Amigdoscalpellum can be divided into two groups. In the species group with radial stripes, the new species here described, A. dorsituberculatum sp. nov., differs from other species by the dorsal part of the carina being round and arched, the roof without lateral ribs and median furrow; the infra-median latus wider triangular, its length on the basal margin greater than its height; and by the vestigial form of the caudal appendage. A key to the species of Amigdoscalpellum is provided. [ABSTRACT FROM AUTHOR]

This study analyzes the pH of surface-sediment porewater (i.e. 2–3 cm below the water-sediment interface), and concentrations of CaCO 3 and organic carbon (OC) in 1192 sediment cores from the northern South China Sea, in water depths ranging from 137 to 3702 m. This is the first study in the literature to analyze the large-scale spatial variability of deep-water surface-sediment pH over a large ocean basin. The data showed strong spatial variations in pH. The lowest pH values (<7.3) were observed south of Hainan Island, an area that is affected by summer upwelling and freshwater runoff from the Pearl and Red Rivers. Moderately low pH values (generally 7.3–7.5) occurred in two other areas: a submarine canyon, where sediments originated partly from the Pearl River and correspond to a paleo-delta front during the last glacial period; and southwest of Taiwan Island, where waters are affected by the northern branch of the Kuroshio intrusion current (KIC) and runoff from Taiwan rivers. The surface sediments with the highest pH (⩾7.5, and up to 8.3) were located in a fourth area, which corresponded to the western branch of the KIC where sediments have been intensively eroded by bottom currents. The pH of surface-sediment porewater was significantly linearly related to water depth, bottom-water temperature, and CaCO 3 concentration ( p < 0.05 for the whole sampling area). This study shows that the pH of surface-sediment porewater can be sensitive to characteristics of the overlying water column, and suggests that it will respond to global warming as changes in surface-ocean temperature and pH progressively reach deeper waters. [ABSTRACT FROM AUTHOR]

Se describe la pesca artesanal de cangrejo dorado (Chaceon chilensis) en las islas Robinson Crusoe y Santa Clara, en el archipiélago de Juan Fernández (Chile), desarrollada entre julio de 2005 y mayo de 2006. Se dan a conocer aspectos biológico-pesqueros relativos a esfuerzo y rendimientos de pesca, proporción sexual, así como los resultados de una evaluación directa de biomasa vulnerable mediante el método de area de influencia de las trampas. La extracción se efectuó fundamentalmente en el cuadrante NE de ambas islas, mediante botes de madera de 9,0 m de eslora. Se monitorearon 157 salidas de pesca y se capturaron 13.903 ejemplares, los cuales mayoritariamente fueron machos (97,5%). La CPUE promedio fue 16,7 ejemplares por trampa y de 13,5 ejemplares comerciales por trampa. A partir del muestreo sistemático, se detectó al recurso entre 300 y 1000 m de profundidad, con mayores rendimientos entre 400 y 500 m de profundidad (19,8 y 15,9 ejemplares por trampa). Se consideran y discuten dos escenarios de evaluación de stock para ejemplares de talla comercial en el area actualmente explotada (45,8 km ), el primero estimó un radio efectivo para las trampas de 13,4 m (area de 564,1 m ), con una biomasa vulnerable de 1.002 ton, equivalentes a 832.983 ejemplares, mientras que el segundo consideró un radio de 30,0 m con una biomasa vulnerable de 203 ton equivalente a 168.587 ejemplares.This work describes the artisanal golden crab (Chaceon chilensis) fishery off Robinson Crusoe and Santa Clara islands in the Juan Fernández archipelago (Chile) developed between July 2005 and May 2006. We report biological fishery aspects related to the físhing efforts and yields, the sexual proportion of the catch, and the results of a direct evaluation of the vulnerable biomass done using the trap area of influence method. The extraction was done mainly in the NE quadrant of both islands from wooden boats (9.0 m length). Monitoring was done during 157 físhing trips, in which 13,903 specimens were caught; most were males (97.5%). The average CPUEs were 16.7 specimens per trap and 13.5 commercial specimens per trap. Systematic sampling revealed the resource between 300 and 1000 m depth, with the greatest yields between 400 and 500 m depth (19.8 and 15.9 specimens per trap). Two stock assessment scenarios were considered and discussed for commercial-sized specimens in the currently exploited area (45.8 km ). The first scenario esti-mated an effective radius for the traps of 13.4 m (564.1 m² in area ), obtaining a vulnerable biomass of 1002 tons, equivalent to 832,983 specimens. The second scenario considered a radius of 30.0 m, giving a vulnerable biomass of 203 tons, or 168,587 specimens.

Se describe Paralomis sonne sp. nov, capturada frente a Antofagasta (22°48,07'S-70°42,29'W) a una profundidad de 1775 m, durante el desarrollo de la expedición PUCK-156 a bordo del RV Sonne. La presencia de un caparazón densamente cubierto de espinas agudas, lo diferencia del resto de las especies chilenas del mismo género. Este hallazgo, corresponde a la décima especie de este género para aguas del Pacífico suroriental.Paralomis sonne n. sp. is described from material collected off Antofagasta, Chile (22°48,07'S-70°42,29'W) at 1,775 m depth during the PUCK-156 expedition on board the RV Sonne. The carapace of this new species is densely covered with sharp spines, which differentiates it from all other Chilean species of the same genus. This is the tenth species of the genus recorded in southeastern Pacific waters.

Reproduction of the brooding feather star Phrixometra nutrix was studied from the deep southwestern Atlantic Ocean. Samples were collected using dredge trawlers and fishing nets on board the B/O Puerto Deseado, between 91 and 512 m depth. Reproductive biology was studied using modern optical techniques including histology and scanning electron microscopy. Here we present the first record of genital papillae for class Crinoidea. Genital papillae have been reported in all extant echinoderm classes except for Crinoidea. In addition, a high proportion (16%) of hermaphroditic specimens was found in the analyzed samples. Finally, cystidean and pentacrinoid stages were found inside the marsupium of Phrixometra nutrix. It is expected that this work will enable further discoveries of crinoid reproductive biology considering the ecological and phylogenetic importance of brooding crinoids. [ABSTRACT FROM AUTHOR]

The processes mediated by microbial planktonic communities occur along the entire water column, yet the microbial activity and composition have been studied mainly in surface waters. This research examined the vertical variation in bacterial abundance, activity and community composition and structure from surface down to 5000 m depth following a longitudinal transect off the Galician coast (NW Iberian margin, from 43°N, 9°W to 43°N, 15°W). Community activity and composition changed with depth. The leucine incorporation rates decreased from the euphotic layer to the bathypelagic waters by three orders of magnitude, whereas prokaryotic abundance decreased only by one order of magnitude. The relative abundance of SAR11 and Alteromonas, determined by catalyzed reported deposition fluorescence in situ hybridization (CARD-FISH), decreased with depth. Meanwhile, the contribution of SAR 202 and SAR324 was significantly higher in the deeper layers (i.e. NEADW, North East Atlantic Deep Water and LDW, Lower Deep Water) than in the euphotic zone. Bacterial community structure, assessed by Automated Ribosomal Intergenic Spacer Analysis (ARISA), was depth-specific. A distance based linear model (DistLM) revealed that the variability found in bacterial community structure was mainly explained by temperature nitrate, phosphate, dissolved organic matter (DOM) fluorescence, prokaryotic abundance, leucine incorporation and to a lesser extent salinity, oxygen, CDOM absorbance and dissolved organic carbon concentration. Our results displayed a bacterial community structure shaped not only by depth-related physicochemical features but also by DOM quality, indicating that different prokaryotic taxa have the potential to metabolize particular DOM sources. [ABSTRACT FROM AUTHOR]

In the last decades, the decline of coastal waters resources has forced fisheries to expand into deeper waters. However, while the increase of industrial activities make it essential to find biological models that can explain pollutants dynamics, little is still known about pollutants distribution, dynamics, and their possible effects on deep-water organisms. In this context, new information on the concentrations of trace metals (Arsenic, As; Cadmium, Cd; Copper, Cu; Mercury, Hg; Lead, Pb) in muscle, liver and gonads of blackmouth catshark, Galeus melastomus, from north-western Mediterranean (northern Tyrrhenian Sea) are presented. Significant differences between males and females were found in the concentrations of three of the five trace elements in gonads. Lower concentrations of trace metals were found in the ovaries, and this could be due to the almost continuous vitellogenic activity which could transfer contaminants to developing oocytes. [ABSTRACT FROM AUTHOR]

The presence of Laubierina peregrinator Warén & Bouchet, 1990 (Tonnoidea: Laubierinidae) is reported for the first time in the continental slope of Argentina at a depth of 2934 m. This constitutes the first mention of the species in the literature other than the original description. Minor differences of shell and radula are compared with the original description. This record, together with two others from southwestern Africa and Mozambique Channel, suggest that L. peregrinator is a southern hemisphere species. [ABSTRACT FROM AUTHOR]

In this study, we report spatial and vertical profiles of suspended particle-associated polycyclic aromatic hydrocarbons (PAHs) collected from nine stations across the open eastern Mediterranean Sea (Ionian and northwestern Levantine Seas — EMS) corresponding to various water column depths (1008–4087 m). Concentrations of total determined PAHs (sum of 16 compounds) ranged between 90.6 and 918 pg L − 1 comparable to those reported for unpolluted open/deep-sea settings. Values recorded for particles in mesopelagic and bathypelagic waters were fairly comparable to those measured in surface particulate matter, implying that deep EMS waters constitute a pollutant depository. The occurrence of the studied PAHs is attributed to a mixed contribution from both fossil and pyrolytic compounds, while results are indicative of chronic petrogenic pollution in the study area, with a prominent fossil PAHs signal in deep waters. The residence time of suspended particle-associated PAHs in the water column (considering only particle settling) was estimated at approximately 30 y, while their spatial and vertical distribution patterns exhibited distinct characteristics amongst the studied sites with their overall occurrence and fate being controlled by both biogeochemical processes and water mass circulation patterns. [ABSTRACT FROM AUTHOR]

The AbyssBox project aims to provide the first permanent public exhibition of live deep-sea hydrothermal fauna maintained at in situ pressure. AbyssBox is a pressurized aquarium designed to function permanently. Here we present details of the project after the public exhibition functioned for more than three years at Océanopolis aquarium in Brest, France. We also describe the AbyssBox pressure aquarium, and provide data and observations on vent shrimp ( Mirocaris fortunata ) and crabs ( Segonzacia mesatlantica ) that were sampled from 1700 m depth at the Lucky Strike vent field (Mid-Atlantic Ridge) during different cruises. While mortalities exceeded 50% during the first days following sampling, the remaining animals appeared to acclimate fairly well. Some crabs have now been kept for more than 2 years, and some shrimp have spent more than 3 years in captivity. Primarily designed for a public exhibition, the AbyssBox is already used for scientific purposes, since it provides one of the most effective tools for long-term rearing of deep-sea fauna. AbyssBox is a first step towards maintaining a variety of deep-sea fauna year-round at in situ pressure, which will serve both scientific and public interests. [ABSTRACT FROM AUTHOR]

Data on the distribution, abundance and biological parameters of the giant red shrimp Aristaeomorphafoliacea were collected during a research survey in deep waters (600-4000 m) of the Mediterranean Sea at three locations: the Balearic Sea, the western Ionian and the eastern Ionian in early summer 2001. The shrimp was mainly found in the shallower zone (< 1000 m) of the eastern Ionian Sea. Few specimens were caught in the deeper waters of this region, with 1100 m being the lower limit of its distribution. This is the maximum depth reported for the species in the Mediterranean. At the other two locations, the species was scarcely caught and only in the shallowest zone (< 1000 m). In the area and depth zone of high abundance, 5 modal groups for females and 3 for males were distinguished using the Bhattacharya method. The recruitment seems to take place at the shallowest stations (600 m). More than 50% of adult females were in advanced maturity stages. The striking abundance differences of the species between the western and eastern locations may be explained by the different exploitation level of the deep waters (almost null in the eastern Ionian Sea and extensive more westwards). However, the distribution and biological characteristics of A.foliacea indicate a higher vulnerability to over-fishing comparing to the other commercial co-occurring deep-water shrimp Aristeusantennatus.

A new species of Systellaspis Spence Bate, 1888, Systellaspis liui sp. nov., was discovered in the deep waters of the western Pacific. It is closely allied to 5. debilis (A. Milne-Edwards, 1881), but it differs morphologically in the blade of the scaphocerite being equipped with a medial dorsal groove, the spines on pereiopods 1 to 5, the dorsal margin of the third abdominal somite with a carina, the posterior margin of the fifth abdominal somite,, the dorsal margin of the telson armed with at least two rows of spines on each side. A key to the species of Systellaspis is provided. [ABSTRACT FROM AUTHOR]

The warming of deep waters in the Nordic seas is identified based on observations during Chinese 5th Arctic Expedition in 2012 and historical hydrographic data. The most obvious and earliest warming occurrs in the Greenland Basin (GB) and shows a coincident accelerated trend between depths 2 000 and 3 500 m. The observations at a depth of 3 000 m in the GB reveal that the potential temperature had increased from −1.30°C in the early 1970s to −0.93°C in 2013, with an increase of about 0.37°C (the maximum spatial deviation is 0.06°C) in the past more than 40 years. This remarkable change results in that deep waters in the center of the Lofton Basin (LB) has been colder than that in the GB since the year 2007. As for the Norwegian Basin (NB), only a slight trend of warming have been shown at a depth around 2 000 m since the early 1980s, and the warming amplitude at deeper waters is just slightly above the maximum spatial deviation, implying no obvious trend of warming near the bottom. The water exchange rate of the Greenland Basin is estimated to be 86% for the period from 1982 to 2013, meaning that the residence time of the Greenland Sea deep water (GSDW) is about 35 years. As the weakening of deep-reaching convection is going on, the abyssal Nordic seas are playing a role of heat reservoir in the subarctic region and this may cause a positive feedback on the deep-sea warming in both the Arctic Ocean and the Nordic seas. [ABSTRACT FROM AUTHOR]

The significance of Joule-Thomson effect in petroleum industry applications has extensively been documented in the literature. In the first part of an extensive literature survey conducted on the significance of Joule-Thomson effect in petroleum fields Yadali Jamaloei and Asghari, 2015, this effect was presented in well testing, in multilateral/slanted wells, in drilling/completion/production operations, and in hydrate formation. In this article, the second part of this comprehensive review is presented, which consists of Joule-Thomson effect in CO2injection into depleted natural gas reservoirs, in prediction of wellbore temperature profiles, and the influence of thermal stresses resulting from this effect on the wellbore stability. It is expected that this article will serve as a reference tool for the engineers interested in the Joule-Thomson effect in petroleum fields. [ABSTRACT FROM AUTHOR]

Sperm whales (Physeter macrocephalus) are widely distributed in deep waters worldwide, yet relatively little is known about this species in the South China Sea (SCS). Here, an integrated approach was used to investigate sperm whales in this region. First, we compiled records of 28 strandings, two bycatch events, and 63 opportunistic sightings of sperm whales in the SCS, and these historical records indicated that sperm whales have occurred occasionally in the SCS. Second, we conducted four ship-based surveys from 2019 to 2021 to investigate cetaceans in the northern SCS. During these surveys, we recorded 125 cetacean sightings, including nine sperm whale sightings, with a group size of 5.1 ± 2.3 individuals (mean ± SD). Of nine sperm whale sightings, seven were determined to be nursery groups, with 1–2 calves/juveniles per group. This finding suggests that the northern SCS might be a nursing ground for sperm whales. Twenty-two individuals were photographically identified from six groups with no resightings, indicating that there are probably more whales within the investigated area that have not been identified. Third, we tagged three adult sperm whales from a nursery group with LIMPET satellite tags on July 24, 2020. Satellite-tracking data showed that these whales occupied a relatively small area (≤2200 km2) within <10 days, with an estimated travel distance of ≤400 km for each individual. To conclude, this is the first study to document the frequent existence and probable residence of sperm whales in the northern SCS. Considering that sperm whales in this area may represent only a small portion of the entire SCS population, additional field surveys and biologging efforts are required to investigate sperm whales in the SCS and help reveal the broad distribution, movement patterns, and habitat preferences of this species in the region. • Sperm whales in the South China Sea (SCS) were investigated using an integrated approach. • Nine sperm whale groups (including seven nursery groups with calves/juveniles) were observed in the northern SCS. • The northern SCS, especially Xisha Trough waters, might be a nursing ground for sperm whales. [ABSTRACT FROM AUTHOR]

A deep-sea pedunculate barnacle of the family Scalpellidae, subfamily Arcoscalpellinae, collected from deep waters of the South China Sea is studied.Sinoscalpellumgen. nov. is erected to accommodateSinoscalpellum sinensissp. nov. The new genus differs from the other genera by the inframedian latus narrow and long, umbo at basi-rostral angle and protruded to below rostrum. A key to genera of the subfamily Arcoscalpellinae is provided. http://www.zoobank.org/urn:lsid:zoobank.org:pub:061A3277-012E-4808-B7BA-3180CF910CD7 [ABSTRACT FROM AUTHOR]

An optimum multiparameter analysis was applied to a data set for the eastern boundary of the North Atlantic subtropical gyre, gathered during November of two consecutive years and spanning from 16 to 36º N. This data set covers over 20º of latitude with good meridional and zonal resolution over the whole coastal transition zone. The contribution from six water types in the depth range between 100 and 2000 m is solved. In the 100 to 700 m depth range the central waters of southern and northern origin meet abruptly at the Cape Verde Frontal Zone. This front traditionally has been reported to stretch from Cape Blanc, at about 21.5º N, to the Cape Verde Islands, but in our case it penetrates as far as 24º N over the continental slope. South of 21º N latitude we actually find a less saline and more oxygenated variety of South Atlantic Central Water, which we ascribe to less diluted equatorial waters. In the 700 to 1500 m depth range the dominant water type is a diluted form of Antarctic Intermediate Water (AAIW), whose influence smoothly disappears north of the Canary Islands as it is replaced by Mediterranean Water (MW); at latitudes where both water masses coexist, we observe MW offshore while AAIW is found near-shore. North Atlantic Deep Water is the dominating water type below about 1300/1700 m depth south/north of the Canary Islands; this abrupt change in depth suggests the existence of different paths for the deep waters reaching both sides of the archipelago.

Abstract: The opisthobranch fauna (Gastropoda: Opisthobranchia) of the deep sea basins of the Sea of Japan is reviewed. A detailed description of the most common deep sea nudibranch species Coryphella japonicaVolodchenko, 1941 is given based on materials from various expeditions (including R/V “Vityaz” cruises and SoJaBio project). Distinct morphological features of C. japonica are discussed and its valid taxonomic status is confirmed. The considerable radular variability of C. japonica for the first time is documented using a scanning electron microscope. Unique features of the bathymetric distribution of C. japonica ranging from shelf to the abyssal depths are discussed in connection with the “pseudabyssal area” concept. C. japonica was compared to its assumed synonym C. salmonacea, and to similar C. athadona. Material from all these species, including types of C. japonica, was examined externally, anatomically via dissection, and SEM. C. salmonacea is restricted to North Atlantic and Arctic only, whereas C. japonica inhabits NE Pacific including deep water basins of the Sea of Japan. [Copyright &y& Elsevier]

Data on deep sea leptostracans (Crustacea: Phyllocarida: Leptostraca) are still scarce in many parts of the world. In the last few years, several species of Nebalia Leach, 1814, have been reported from the eastern Mediterranean; however, there have been no reports from waters deeper than 100 m. Samples collected recently from Gökçeada, Turkey--at depths of 680-820 m in the Aegean Sea, eastern Mediterranean--included Nebalia abyssicola Fage, 1929. This is the first record for the study area and one of the few known records of this species. Specimens are described and figured to complement previous descriptions. A key for all known leptostracans from the eastern Mediterranean is also provided. [ABSTRACT FROM AUTHOR]

A new species of softnose skate (Arhynchobatidae) is described, based on a single adult male measuring 895 mm TL that was collected at a depth of 953-1,022 m on the Coriolis Bank off western New Caledonia in the southwestern Pacific Ocean. The specimen conforms to the genus Bathyraja in having the rostral cartilage continuous with the neurocranium and very slender and uncalcified over its length. Bathyraja leucomelanos sp. nov. differs from its congeners through a combination of the following characters: distinctive coloration of the disc with white dorsal and black ventral surfaces, dorsal surface of the disc entirely covered with dermal denticles, ventral surface naked, anterior portion of the anterior margin of the disc straight, snout long and very broad with orbit about 6.0 times in preorbital length, orbit 0.73 times interorbital width, mouth 6.8% TL, tail 0.88 times precloacal length, accessory terminal 2 cartilage of the clasper having an expanded disc-shaped tip, and alar thorn tip undulating. Molecular barcoding from the COI sequence reveals that this new species is genetically close to B. spinicauda from the North Atlantic Ocean. [ABSTRACT FROM AUTHOR]

Abstract: Seven years (2001–2008) of dissolved organic carbon (DOC) vertical profiles were examined in order to assess the main processes determining DOC concentration and distribution in the meso- and bathypelagic layers of the Mediterranean Sea. As expected, DOC showed high and highly variable concentrations in the surface layer of 57–68μM (average values between 0 and 100m), with a decrease to 44–53μM between 200 and 500m. Deep DOC distribution was strongly affected by deep-water formation, with a significant increase to values of 76μM in recently ventilated deep waters, and low concentrations, comparable to those observed in the open oceanic waters (34–45μM), where the oldest, deep waters occurred. In winter 2004/2005 a deep-water formation event was observed and the consequent DOC export at depth was estimated to range between 0.76–3.02TgCmonth–1. In the intermediate layer, the main path of the Levantine Intermediate Water (LIW) was followed in order to estimate the DOC consumption rate in its core. Multiple regression between DOC, apparent oxygen utilization (AOU), and salinity indicated that 38% of the oxygen consumption was related to DOC mineralization when the effect of mixing was removed. In deep waters of the southern Adriatic Sea a DOC decrease of 6μM, together with an AOU increase of 9μM, was observed between the end of January 2008 and the end of June 2008 (5 months). These data indicate a rate of microbial utilization of DOC of about 1.2μMCmonth−1, with 92% of the oxygen consumption due to DOC mineralization. These values are surprisingly high for the deep sea and represent a peculiarity of the Mediterranean Sea. [Copyright &y& Elsevier]

Until recently, ammonia oxidation, a key process in the global nitrogen cycle, was thought to be mediated exclusively by a few bacterial groups. It has been shown now, that also Crenarchaeota are capable to perform this initial nitrification step. The abundance of ammonia oxidizing Bacteria and Archaea was determined using the bacterial and archaeal ammonia monooxygenase-α subunit (amoA) gene as functional markers in a quantitative PCR approach and related to the abundance of Bacteria and Archaea in the Eastern Mediterranean Sea. Archaeal amoA copy numbers decreased from 4000–5000 copies ml−1 seawater from the 200–500 m depth layer to 20 copies ml−1 at 1000 m depth. β-Proteobacterial amoA genes were below the detection limit in all the samples. The archaeal amoA copy numbers were correlated with NO2− concentrations, suggesting that ammonia-oxidizing Archaea may play a significant role in the nitrification in the mesopelagic waters of the Eastern Mediterranean Sea. In the bathypelagic waters, however, archaeal amoA gene abundance was rather low although Crenarchaeota were abundant, indicating that Crenarchaeota might largely lack the amoA gene in these deep waters. Terminal restriction fragment length polymorphism analysis of the archaeal community revealed a distinct clustering with the mesopelagic community distinctly different from the archaeal communities of both, the surface waters and the 3000–4000 m layers. Hence, the archaeal community in the Eastern Mediterranean Sea appears to be highly stratified despite the absence of major temperature and density gradients between the meso- and bathypelagic waters of the Mediterranean Sea.The ISME Journal (2009) 3, 147–158; doi:10.1038/ismej.2008.94; published online 25 September 2008 [ABSTRACT FROM AUTHOR]

Data were collected during an exploratory trawl survey in the deep waters (300-900 m) of the southern part of the Greek Ionian Sea. A multivariate analysis of the abundance of the species in the various stations revealed the existence of two main distinct groups corresponding to the depth zones 300-500 m and 500-900 m. A secondary separation between the stations of the zone 500-700 m and those of the zone 700-900 m was observed. In the shallowest zone, the dominant species was Chlorophthalmus agassizii followed by Plesionika edwardsii, Hymenocephalus italicus, Argentina sphyraena and Plesionika antigai. In the depth stratum 500-700 m, the most abundant species were Aristaeomorpha foliacea, Plesionika martia, Chlorophthalmus agassizii and Hoplostethus mediterraneus. The most abundant species in the depth stratum 700-900 m were the red shrimps Aristaeomorpha foliacea and Aristeus antennatus. The results of the assemblage composition are compared to those of other relevant areas and are discussed considering the fishing intensity and environmental conditions. [ABSTRACT FROM AUTHOR]

Abstract: We present a detailed account of the changing hydrography and the large-scale circulation of the deep waters of the Eastern Mediterranean (EMed) that resulted from the unique, high-volume influx of dense waters from the Aegean Sea during the 1990s, and of the changes within the Aegean that initiated the event, the so-called ‘Eastern Mediterranean Transient’ (EMT). The analysis uses repeated hydrographic and transient tracer surveys of the EMed in 1987, 1991, 1995, 1999, and 2001/2002, hydrographic time series in the southern Aegean and southern Adriatic Seas, and further scattered data. Aegean outflow averaged nearly 3×106 m3 s−1 between mid-1992 and late 1994, and was largest during 1993, when south and west of Crete Aegean-influenced deep waters extended upwards to 400m depth. EMT-related Aegean outflow prior to 1992, confined to the region around Crete and to ∼1800m depth-wise, amounted to about 3% of the total outflow. Outflow after 1994 up to 2001/2002, derived from the increasing inventory of the tracer CFC-12, contributed ∼20% to the total, of ∼2.8×1014 m3. Densities in the southern Aegean Sea deep waters rose by 0.2kg/m3 between 1987 and 1993, and decreased more slowly thereafter. The Aegean waters delivered via the principal exit pathway in Kasos Strait, east of Crete, propagated westward along the Cretan slope, such that in 1995 the highest densities were observed in the Hellenic Trench west of Crete. Aegean-influenced waters also crossed the East Mediterranean Ridge south of Crete and from there expanded eastward into the southeastern Levantine Sea. Transfer into the Ionian mostly followed the Hellenic Trench, largely up to the trench’s northern end at about 37°N. From there the waters spread further west while mixing with the resident waters. Additional transfer occurred through the Herodotus Trough in the south. Levantine waters after 1994 consistently showed temperature–salinity (T–S) inversions in roughly 1000–1700m depth, with amplitudes decreasing in time. The T–S distributions in the Ionian Sea were more diverse, one cause being added Aegean outflow of relatively lower density through the Antikithira Strait west of Crete. Spreading of the Aegean-influenced waters was quite swift, such that by early 1995 the entire EMed was affected. and strong mixing is indicated by near-linear T–S relationships observed in various places. Referenced to 2000 and 3000dbar, the highest Aegean-generated densities observed during the event equaled those generated by Adriatic Sea outflow in the northern Ionian Sea prior to the EMT. A precarious balance between the two dense-water source areas is thus indicated. A feedback is proposed which helped triggering the change from a dominating Adriatic source to the Aegean source, but at the same time supported the previous long-year dominance of the Adriatic. The EMed deep waters will remain transient for decades to come. [Copyright &y& Elsevier]

We present and assess the distribution of neon in South Atlantic and South Pacific waters, on the basis of more than 3000 mostly new neon data which were obtained primarily under the hydrographic program of the World Ocean Circulation Experiment (predominantly southern summer to fall cruises). Data precision is better than±0.5%, and the set is internally consistent within±0.3% and partly better, and compatible with reported high-quality neon values. Using suitably averaged data (precision 0.1–0.3%), we find that the total range of neon anomalies relative to a solubility equilibrium with atmospheric neon at the observed potential temperature and salinity (using the solubilities of Weiss, J. Chem. Eng. Data 16 (1971) 235) is approximately 0–4%, and below 2000 m depth, 3–4% only. We consistently observe two types of neon depth profiles, one for the temperate-latitudes ocean, which is characterized by a near-surface maximum and a minimum in Antarctic Intermediate Water, and one for the Southern Ocean that essentially displays a steady increase with depth. The neon distribution reflects the influence of air injected by submerged air bubbles, the areal distribution of atmospheric pressure, seasonal temperature changes in the mixed layer and solar heating below it, and interaction with sea ice and glacial ice, largely in keeping with previous work. However, it appears that interaction with sea ice reduces neon anomalies distinctly less than the literature suggests. The temperate-ocean shallow maxima point to widespread subsurface heating in the course of the summer season by roughly 1 K. Among the major source water masses of the deep waters, the neon anomalies are lowest in Antarctic Intermediate Water (∼1.5%), intermediate in North Atlantic Deep Water (∼3%, confirming previous work) and similarly in Circumpolar Deep Water, and highest in Antarctic Bottom Water (∼3.8%). The anomalies in Southeast Pacific deep waters (>2500 m) are comparatively less (only∼3.3%), as a result of the contribution of Antarctic Intermediate Water. The present study is the first attempt to deal with the oceanic distribution of neon in a systematic fashion. The results can serve to assist assessments of the oceanic distributions of other dissolved gases. [Copyright &y& Elsevier]

A new species of deep-water barnacle that belongs to the family Scalpellidae is described from the South China Sea. Arcoscalpellum liui sp. nov. is morphologically similar to Arcoscalpellum gryllum Zevina, but differs from the latter by the absence of longitudinal striae on the capitular plates and the presence of caudal appendages with few terminal setae. [ABSTRACT FROM AUTHOR]

Investigates the in vivo absorption spectrum and the pigment composition of Palmophyllum crassum collected from the shaded rocky bottom in deep waters. Determination of the molar ratio of chlorohyll in the either solution of pigments extracted from the green alga; Accounts on the chromatography of the pigments; Detection of two kinds of unknown carotenoids on the chromatogram of Pigments of the algae.

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 location within the egg masses, and supported by an individual cord. These are connected to a central and more robust primary cord by an oral extension. Eggs were found in the gonads, the initial stages of development were located along the arms to the oral area and some stages were protruding from the mouth, into the everted stomach. A hermaphrodite specimen was found with both types of gonads (male and female). The information obtained suggests a reproductive period of at least five months, continued reproduction should not be ruled out. This species supports the hypothesis that brooding condition predominates in the deep-sea. The present study represents the first record of this type of reproduction in the deep waters of the Southwest Atlantic. • A new brooder genus and species. • Earlier stages found along the arms to the oral area. • Stages protruding from the mouth, inside the evert stomach. • Each oral broods located in a specific place and all connected by a cord. • A case of hermaphroditism. [ABSTRACT FROM AUTHOR]

Lagrangian studies are very useful in predicting deepwater environmental impacts such as oil and gas extraction operations. The purpose of this work was to improve our understanding of the connectivity of the deep Gulf of Mexico (GoM), by complementing the Lagrangian observational dataset provided by subsurface float observations with virtual particles generated by numerical simulation. Our findings emphasize the important role of the deep cyclonic gyre in the connectivity of GoM deep waters. Using Lagrangian coherent structures, we provide compelling evidence that the deep gyre forms an enclosed region in the western GoM restricting the transport between the eastern and western Gulf mainly to the boundary currents around its outer edges. A synthesis of observations and the model results is presented in a schematic Lagrangian mean circulation map that could be used by multidisciplinary scientists to obtain a comprehensive view of the connectivity between different regions of the GoM deep waters. • A reliable connectivity estimation of the deep Gulf of Mexico (GoM) is presented. • The deep cyclonic gyre plays an important role in the connectivity of the deep GoM. • A map of the prevailing Lagrangian circulation for the deep GoM is provided. [ABSTRACT FROM AUTHOR]