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We investigate a hydrodynamic equation system which—with some approximation—is capable of describing the tsunami propagation in the open ocean with the time-dependent self-similar Ansatz. We found analytic solutions of how the wave height and velocity behave in time and space for constant and linear seabed functions. First, we study waves on open water, where the seabed can be considered relatively constant, sufficiently far from the shore. We found original shape functions for the ocean waves. In the second part of the study, we also consider a seabed which is oblique. Most of the solutions can be expressed with special functions. Finally, we apply the most common traveling wave Ansatz and present relative simple, although instructive solutions as well. [ABSTRACT FROM AUTHOR]

The article reports that researchers at the Scripps Institution of Oceanography (University of California) have found an exponential increase in plastic deposition from 1945 to 2009 in the sediments of Santa Barbara Bay, with a doubling time of 15 years. This increase was closely correlated with global plastic production and the increase in the population living in the southern California coastal area in the same period.

Ocean warming can drive poleward shifts of commercially important species with potentially significant economic impacts. Nowhere are those impacts greater than in the Gulf of Maine where North America's most valuable marine species, the American lobster (Homarus americanus Milne Edwards), has thrived for decades. However, there are growing concerns that regional maritime economies will suffer as monitored shallow water young‐of‐year lobsters decline and landings shift to the northeast. We examine how the interplay of ocean warming, tidal mixing, and larval behavior results in a brighter side of climate change. Since the 1980s lobster stocks have increased fivefold. We suggest that this increase resulted from a complex interplay between lobster larvae settlement behavior, climate change, and local oceanographic conditions. Specifically, postlarval sounding behavior is confined to a thermal envelope above 12°C and below 20°C. Summer thermally stratified surface waters in southwestern regions have historically been well within the settlement thermal envelope. Although surface layers are warming fastest in this region, the steep depth‐wise temperature gradient caused thermally suitable areas for larval settlement to expand only modestly. This contrasts with the northeast where strong tidal mixing prevents thermal stratification and recent ocean warming has made an expansive area of seabed more favorable for larval settlement. Recent declines in lobster settlement densities observed at shallow monitoring sites correlate with the expanded area of thermally suitable habitat associated with warmer summers. This leads us to hypothesize that the expanded area of suitable habitat may help explain strong lobster population increases in this region over the last decade and offset potential future declines. It also suggests that the fate of fisheries in a changing climate requires understanding local interaction between life stage‐specific biological thresholds and finer scale oceanographic processes. [ABSTRACT FROM AUTHOR]

The journal Deep-Sea Research was first published in October 1953 directed by the Joint Commission on Oceanography to focus on the deep-sea floor as the main theme. Here we review the history of the journal through 12 editors and two publishers, Pergamon (1953–1991) and Elsevier (1991-present). From 1962 to 1991 abstracts and bibliographies as well as original research papers were published. From 1992 the journal has focussed on original papers, in two series; Part I for individual submissions and Part II for topical collections of papers compiled by guest editors. The scope of the journal has grown to encompass the entire open ocean from the air-sea interface to beneath the sea floor. From over 10,000 papers, 70 have been selected and are reviewed by the present editors. [ABSTRACT FROM AUTHOR]

Abstract This study proposed and applied a three-dimensional (3-D) numerical model based on existing 1-D and 2-D numerical models to investigate residual soil response in a homogeneous sandy seabed with a rocking mono-pile subjected to a cyclic lateral load and waves. The wave motion is governed by the Reynolds-averaged Navier-Stokes (RANS) equations. Compared to previous studies in the literature, this research analyzed the pore pressure accumulation due to wave-pile-seabed interaction considering the pile rocking effect. The proposed 3-D model is validated against existing experimental and numerical data. Subsequently, the 3-D model is used to investigate the residual response of a seabed with a mono-pile, in which pile rocking caused by a lateral cyclic load is considered. The results indicate that the existence of a rocking mono-pile greatly affects the residual response of the seabed due to pile-seabed interaction. The rate of residual pore pressure buildup was significantly faster near the mono-pile surface due to the impermeable interface and stiffness difference of the pile and seabed soil. In addition, the effect of pile rocking leads to the variation in shear stress in various parts of the seabed, resulting in different residual pore pressure variations at various positions around the mono-pile. [ABSTRACT FROM AUTHOR]

The provenance of the Central Yellow Sea Mud (CYSM) in the Yellow Sea has been attracted a great deal of attention over the last three decades, but a consensus is not yet reached. In this study, 101 surface sediment samples collected from the CYSM were investigated to determine provenance and transport mechanisms in the area using the clay minerals and major element components. The Huanghe sediments are characterized by higher smectite, but the Changjiang sediments are more abundant illite contents. Western Korean rivers contain more kaolinite and chlorite than do Chinese rivers. The Chinese rivers have higher Fe2O3, MgO, and CaO than the Korean rivers at the same Al2O3 concentration. Therefore, the clay minerals and major element concentrations can be useful indicator for the source. Based on our results, we suggest that the surface sediments in CYSM were composed mainly of Changjiang sediments, mixed a partly with sediments from the Huanghe and the western Korean rivers. Although the northwestern part of CYSM is proximate to the Huanghe, the contents of smectite and CaO were extremely low. It could be evidence that the Huanghe materials do not enter directly into the CYSM due to the Shandong Peninsula Front. Considering the oceanic circulation in the Yellow Sea, the Changjiang sediments could be transported eastward with the Changjiang Diluted Water and then mixed in CYSM via the Yellow Sea Warm Current (YSWC). Huanghe sediments could be provided by coastal currents (Shandong Coastal Current and Yellow Sea Coastal Current) and the YSWC. In addition, sediments from western Korean rivers might be supplied into the CYSM deposit via the Korean Coastal Current, Transversal Current, and YSWC. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Fluid flow resulted in complex fluid escape structures, mainly after the Miocene. • The fluid compositions are likely multi-source. • Active fluid escape features are indicated by seafloor fluid pathways and plumes. • Gravity flows along gullies contributed to the observed asymmetric morphologies. • Bottom currents and eddies may play important roles in sediment remobilization. Abstract Mega-pockmarks, which can reach a few kilometers in width and a few hundred meters in depth, and associated fluid escape features in the Northern Zhongjiannan Basin, South China Sea, have received much attention in the recent years, due to their large variety of morphologies and sizes. In this work, an integrated interpretation of detailed multibeam bathymetry, conventional multi-channel seismic reflection and seismic oceanography sections covering the northern Zhongjiannan Basin, South China Sea, are used to image the seafloor morphology, the subsurface geology and the water column, in order to better understand the geological and oceanographic controls on the formation and evolution of the widespread fluid escape features in this region. Regional uplift and volcanism took place in this area near the Palaeogene–Neogene boundary and, during the Neogene–Quaternary post-rift thermal subsidence period, differential subsidence and diapirism deformed the overlying kilometer-scale successions. Mainly after the Miocene, focused flow of fluids originated at depth occurred along gas pipes, polygonal faults, tapered reflectors and faults into the shallow sediments, resulting in intense fluid blowouts and complex fluid escape structures on the seafloor. Our results show that elongated pockmarks, pockmark gullies and gullies in the northern slope are generally controlled by underlying buried channels and gullies. However, pockmark gullies and gullies in the southern slope are controlled by gravity sliding/slumping, along with crescent pockmarks developing parallel to water depth contours. To varying degrees, intense fluid escape activities associated with mud diapirism and gas escape in the study area resulted in mud extrusion and the formation of mud volcanoes, complex seabed morphologies and irregular pockmarks. Mega-pockmarks, collapse structures and blind valleys have formed at the apexes of tectonic uplifts related to volcanism and above basement highs, which suggests that these processes played a role in creating pathways for fluid escape. Bottom currents associated with the South China Sea Western Boundary Current, imaged here for the first time with the seismic oceanographic method, mainly flow to the south, and erode the seafloor, making pockmark walls and slopes of gullies and channels in the north steeper than those in the south. Some fluid escape structures, such as the mega-pockmarks and pockmark gullies, are buried by sediment transported by the bottom currents. Turbidity currents flowing downslope along the long pockmark gullies also erode the seafloor and make the NW slopes of the mud volcanoes less steep than those in the SE. Eddies imaged by the seismic sections may also play a role in transporting sediment to the deep sea in this area. Some of the reported fluid escape structures are still active, as indicated by the fluid pathways that reach the seafloor and plumes in the water column imaged by the seismic sections. [ABSTRACT FROM AUTHOR]

An intricate field of NNW-SSE trending sand ridges was discovered for the first time in 2010 and mapped in detail over the past 6 years during multiple campaigns in the vicinity of the islands of Helgoland and Dune in the German Seabight. The tramline-shaped, elongate, linear and meandering sand ridges are up to 1 km in length, over 10 m in height and spaced 10-50 m apart. The ridges exhibit complex anastomosing patterns, converging and disappearing to the south of the study area and diverging, becoming more subdued and disappearing further to the north. Seismic profiling, surface samples and multibeam data show that the ridges are stationary, while the sediment wave fields to the north and west are migrating westwards. Based on our mapping results, the most likely hypothesis for the development and maintenance of these enigmatic structures is a combination of tidal currents, tides and sediment influx. Whether these structures are associated with the Mesozoic subcrop or are glaciofluvial in origin and have been modified by the last glacial-interglacial intervals or are sedimentary structure linked to Holocene sea level rise in the southern North Sea is a matter of debate. Further studies, including numerical modelling of these sand ridges structures, would provide clues to past sedimentary and hydrodynamic conditions and future changes in the highly dynamic and complex tidal environment of the southern North Sea. [ABSTRACT FROM AUTHOR]

The CryoSat-2 (CS-2) mission is an altimetric mission designed to meet the measurement requirements for ice-sheet elevation and sea-ice ‘freeboard’. In addition to Cryosphere applications, this mission is of great interest to the Hydrosphere and Oceanographic communities since it allows for quantitative assessment of expected enhanced altimetric capabilities in coastal monitoring, ocean floor topography, gravity field and inland water monitoring. The CS-2 main payload is a Synthetic aperture Interferometric Radar ALtimeter (SIRAL) operating in three different modes, including the SAR interferometric mode (SARin). In the work described in this paper, dedicated algorithms are developed for exploiting SARin mode for enhancing the sea level mapping at coastal regions. When operating in SARin mode the altimeter measurements allow for the derivation of the across-track Angle of Arrival (AoA), and so the reflection points at any range bin can be geolocated. In coastal altimetry, land contamination highly degrades the backscattered echo. This is sometimes, overcome with the SARM when tracks are perpendicular to the coast, since this mode provides an along-track resolution enhancement with respect to LRM mode due to the different footprints shapes (LRM is circular, while SARM is a stripe of the same wide across track but only around 300 m along track). However, across-track interferences still remain an issue in coastal altimetry and SARin mode can provide a solution for their mitigation. This paper proposes two different solutions for the improvement of SSH retrievals in coastal zones starting from L1b SARin products, developing post-L1b algorithms. The first solution is based in the use of the AoA. The second solution goes beyond SARin mode, and provides an algorithm for all operational modes, based in the historical window delay within a coastal track section. For both options, a sub-waveform approach is considered for the waveforms cleaning and retracking. In addition, a SAR L2 retracker inherited from the SAMOSA model is adapted to SARin. The results are analyzed and the potential improvements are assessed with respect to SARin data retracker by the CS-2 ground processor. A dedicated CS-2 SARin area (mask) covering the Cuban archipelago has been created for this investigation. A land-sea mask has been created from the Open Street Map high resolution catalogue for this study. A dataset has been produced including both ESA CS2 IPF Baseline B SSH and the SSH series coming from this study. [ABSTRACT FROM AUTHOR]

Abstract The role of deep manned submersibles (DMS) in scientific research of the ocean is considered. The history of development of DMS introduced, drawing attention on the steps, generated by submarine accident ("Thresher") and scientific research jumps (hydrothermal vents discovery). Development of the building of DMS in Russia and particular in P.P.Shirshov Institute of Oceanology RAS is considered, concentrating on world wide research with "Pisces VII" and "Pisces XI" submersibles in 70–80-s of XX century. Short description of MIR-1 and MIR-2 design is introduced, as the best 6000 m DMS in the world. The introduction of various underwater operations of DMS "Mir-1" and "Mir-2", including research of hydrothermal fields on ocean bottom, solution of important state tasks, observations and filming of deep ocean wrecks etc. are described. [ABSTRACT FROM AUTHOR]

We show how, by focusing on bottom pressure measurements particularly on the global continental slope, it is possible to avoid the “fog” of mesoscale variability which dominates most observables in the deep ocean. This makes it possible to monitor those aspects of the ocean circulation which are most important for global scale ocean variability and climate. We therefore argue that such measurements should be considered an important future component of the Global Ocean Observing System, to complement the present open-ocean and coastal elements. Our conclusions are founded on both theoretical arguments, and diagnostics from a fine-resolution ocean model that has realistic amplitudes and spectra of mesoscale variability. These show that boundary pressure variations are coherent over along-slope distances of tens of thousands of kilometres, for several vertical modes. We illustrate the value of this in the model Atlantic, by determining the time for boundary and equatorial waves to complete a circuit of the northern basin (115 and 205 days for the first and second vertical modes), showing how the boundary features compare with basin-scale theoretical models, and demonstrating the ability to monitor the meridional overturning circulation using these boundary measurements. Finally, we discuss applicability to the real ocean and make recommendations on how to make such measurements without contamination from instrumental drift. [ABSTRACT FROM AUTHOR]

The New Zealand Oceanographic Institute (NZOI) laid the foundations for the interactive study of water masses, seabed geology and biota of the Southwest Pacific from 1954 until the demise of the Department of Scientific and Industrial Research in 1992. It was one of the first multidisciplinary marine sciences organisations outside the US and UK. With its brief extending from the seas around New Zealand’s Island Territories near the equator to its Antarctic Ross Dependency, emphasis was always on understanding processes. James Brodie helped set up NZOI, became its first director and initiated many of the mechanisms for its success using a very flat, interactive management style. Initially, equipment, seagoing facilities and accommodation were primitive, but all improved significantly with the acquisition of a custom-build ship and new laboratories. NZOI’s legacy was a huge resource of knowledge that continues to be used within the marine programmes of the National Institute of Water and Atmospheric Research and worldwide. [ABSTRACT FROM AUTHOR]

Limited areas of sea floor have the physiochemical conditions that allow for the formation and preservation of high resolution (yearly or close to yearly) laminated sediments that can function as a historic proxy for past oceanographic and climate conditions. We evaluated and established the fidelity of the sedimentary record in recording these signals by analyzing silicoflagellates production, changes in species composition, skeletal settling and their subsequent burial in bottom sediments at Alfonso Basin. The data series from December 2005 to February 2008 showed similar tendencies in both the vertical flux and overlying euphotic zone (Z eu ) production of silicoflagellates. Both series were numerically dominated by Octactis pulchra with maxima values being recorded for the mixed water column period. Observed differences occurred during the studied years in both magnitude and in flux composition. The presence of a mixed assemblage with (warm–temperate–cold) species such as Dictyocha fibula var. robusta , Dictyocha epiodon and Distephanus speculum could be explained by a synchronization of trends between a predominantly positive Pacific Decadal Oscillation and a positive North Pacific Gyre Oscillation climate phases that were the background conditions underlying the early 2006 through 2007 El Niño event. A Morisita's similarity index value of 97.5% between winter trap and Z eu samples combined with an annualized settling factor of 0.45, suggests that Alfonso Basin is a favorable settling environment for silicoflagellates. However, core-top sediments showed an attenuation of record fidelity (burial factor = 0.25) resulting in a modified record for the production and settling of skeletons. O. pulchra that were not preserved in sediments as the dominant species and with this removal, the signal was also lost of the highest silicoflagellate production season (Mixing-cyclonic eddy periods) from the sedimentary record of the Alfonso Basin. [ABSTRACT FROM AUTHOR]

Recent studies have proposed that the bathymetric fabric of the seafloor formed at mid-ocean ridges records rapid (23,000 to 100,000 years) fluctuations in ridge magma supply caused by sealevel changes that modulate melt production in the underlying mantle. Using quantitative models of faulting and magma emplacement, we demonstrate that, in fact, seafloor-shaping processes act as a low-pass filter on variations in magma supply, strongly damping fluctuations shorter than about 100,000 years. We show that the systematic decrease in dominant seafloor wavelengths with increasing spreading rate is best explained by a model of fault growth and abandonment under a steady magma input. This provides a robust framework for deciphering the footprint of mantle melting in the fabric of abyssal hills, the most common topographic feature on Earth. [ABSTRACT FROM AUTHOR]

The deep biosphere of the subseafloor basalts is recognized as a major scientific frontier in disciplines like biology, geology, and oceanography. Recently, the presence of fungi in these environments has involved a change of view regarding diversity and ecology. Here, we describe fossilized fungal communities in vugs in subseafloor basalts from a depth of 936.65 metres below seafloor at the Detroit Seamount, Pacific Ocean. These fungal communities are closely associated with botryoidal Mn oxides composed of todorokite. Analyses of the Mn oxides by Electron Paramagnetic Resonance spectroscopy (EPR) indicate a biogenic signature. We suggest, based on mineralogical, morphological and EPR data, a biological origin of the botryoidal Mn oxides. Our results show that fungi are involved in Mn cycling at great depths in the seafloor and we introduce EPR as a means to easily identify biogenic Mn oxides in these environments. [ABSTRACT FROM AUTHOR]

The spatial and temporal scales of variability of ocean bottom pressure (P b ) in the Mediterranean Sea are characterized and their relationship with sea level was assessed using a high resolution eddy-permitting regional ocean model spanning the period 1999–2011. It was found that rapid (periods of a few days) bottom pressure fluctuations are coherent with sea level and are decoupled between the eastern and western basins as a result of topographic constraints. In the longer periods, steric processes gained relevance away from the coast and partially broke the coherence between sea level and P b , especially on the western basin. Results confirm that sea level changes are predominantly barotropic over most of the basin and at all time scales, except for the annual cycle. Along the coasts sea level fluctuations reflected local steric processes taking place in their vicinity. This effect was stronger on the western basin, whereas the coasts of the Eastern Mediterranean arise as the most suitable proxies for basin wide long term (> 60 days) mean sea level (or ocean bottom pressure) changes at non-seasonal periods. [ABSTRACT FROM AUTHOR]

Five oceanographic cruises were made between November 2005 and June 2006, sampling a cross-shelf transect off the South Brazilian Bight (SBB; 26°46′S) to follow the seasonal development of the South Atlantic Central Water (SACW) intrusion over the shelf and its influence on the assemblage of planktonic cnidarians. An onshore wind-driven bottom intrusion of the SACW was clearly perceptible, reaching the coast in January. From March onward, the SACW influence was gradually displaced seaward due to wind and tidal mixing. By late June the SACW influence was offshore and the inshore was dominated by low-salinity waters (<34.5). The abundance, distribution, and general taxonomic composition of both medusae and siphonophores were strongly influenced by the onshore intrusion of the SACW. An inshore–offshore gradient was clear. The Canonical Correspondence Analysis suggested that coastal species – dominated by Liriope tetraphylla , actinula larvae and Muggiaea kochi – were mostly related to food availability and a vertically mixed environment inshore, and their abundance and extent were reduced during intrusion periods. In contrast, species with offshore affinities tended to increase their abundance and distribution during intrusion periods, and were mostly related to the presence of thermal stratification and a deep chlorophyll maximum layer. Most of these offshore species, such as Aglaura hemistoma , Rhopalonema velatum and many calycophorans, are associated with the warm upper layer. However, high concentrations of large (>20 mm in diameter) Solmaris corona were observed exclusively in cold waters, suggesting this medusa is a SACW indicator. [ABSTRACT FROM AUTHOR]

The EMSLAB experiment was an ambitious onshore-offshore magnetotelluric (MT) transect of the Cascadia subduction zone. When completed (1985-1988), it was the largest experiment of its kind. Modeling and inversion capabilities at the time were, however, not sufficiently sophisticated to handle a fully regularized inversion of the data, including the seafloor data and bathymetric constraints, with the main final model presented based on trial and error forward modeling of the responses. Moreover, new data collected as part of the Earthscope USArray program are of higher quality due to improvements in instrument technology, and augment the original EMSLAB data set, presenting an opportunity to revisit the structure in this part of the subduction system. We have integrated the original wide-band MT data as well as several long-period stations from the original EMSLAB data set and invert these in conjunction with EMSLAB seafloor responses and new Earthscope data on land. This new composite data set has been analyzed in several ways, within a two-dimensional geometry in which conductivity is assumed to be invariant along a strike direction roughly coincident with that of the subduction zone. We have solved for fully smooth regularized models, as well as solutions that allow discontinuities in conductivity along the top surface of the descending slab. Finally, we have tested specific features in the EMSLAB model, notably a moderately shallow (~30 km depth) forearc conductor. A feature similar to this shallow conductor is a consistent and required feature in our new inversion models, but the new models highlight the connection between the slab and what is interpreted to be an accumulation of aqueous fluids in the deep crust. The depth (~40 km) at which the conductor intersects the slab suggests that the fluids are released by the transition of hydrous basalt to eclogite at upper greenschist facies and higher metamorphic grade. The nose of the mantle wedge has a conductivity consistent with a dry peridotite composition and thermal models of the system. At a depth of around 80 km the mantle intersecting the slab shows a slight increase in conductivity. This increase is not sufficient to require the presence of melt, but a conductor indicative of melt can be inserted into the model at this depth without compromising the fit. [ABSTRACT FROM AUTHOR]

Spatial variation of the velocity field induced by propagation of an interfacial solitary wave (ISW) is one of the most important research themes in marine science. This velocity field together with the vortex within the system can affect marine operations as the ISW propagates in the ocean. The governing equations presently available are modified to model the velocity and vortex, and are used in numerical experiments. This paper presents the results of laboratory experiments and numerical modeling of the velocity field induced by the propagation of an ISW in depression and elevation on a flat bottom. Laboratory observations reveal that the water particle orbits in different water layers have different motion trails due to the effect of the ISW. In addition, the numerical and laboratory experiments show a self-generated vortex above the interface of a depression ISW as it propagates in a stratified two-layer fluid system on a flat bottom. Interestingly, the interface itself may limit the vertical transfer of mass between the upper and bottom layers in a stratified fluid system. [ABSTRACT FROM AUTHOR]

This study examines the global variability of the internal wave field near a depth of 1000 m using data from a set of 194 Argo floats equipped with Iridium communications, capable of measuring hourly temperature and pressure during the park phase of their 10-day cycles. These data have been used to estimate vertical isotherm displacements at hourly intervals, yielding a global measure of the heaving due to internal gravity waves. The displacement results have been employed to examine the global variability of these waves and how the displacement power spectrum compares to the canonical Garrett-Munk spectrum. Using the data, the authors find correlations between internal wave intensity and seafloor roughness, proximity to the seafloor, and the magnitude of the local barotropic velocity. The measurements also show large seamount-trapped waves at high latitudes and coastally trapped subinertial waves. These observations provide a rough global census of the nature of these waves that can ultimately be used in studies of ocean mixing. [ABSTRACT FROM AUTHOR]

This study examines the dispersal of dense water formed in an idealized coastal polynya on a sloping shelf in the absence of ambient circulation and stratification. Both numerical and laboratory experiments reveal two separate bottom pathways for the dense water: an offshore plume moving downslope into deeper ambient water and a coastal current flowing in the direction of Kelvin wave propagation. Scaling analysis shows that the velocity of the offshore plume is proportional not only to the reduced gravity, bottom slope, and inverse of the Coriolis parameter, but also to the ratio of the dense water depth to total water depth. The dense water coastal current is generated by the along-shelf baroclinic pressure gradient. Its dynamics can be separated into two stages: (i) near the source region, where viscous terms are negligible, its speed is proportional to the reduced gravity wave speed and (ii) in the far field, where bottom drag becomes important and balances the pressure gradient, the velocity is proportional to Hc[ g′/( LC d)]1/2 in which H c is the water depth at the coast, g′ the reduced gravity, C d the quadratic bottom drag coefficient, and L the along-shelf span of the baroclinic pressure gradient. The velocity scalings are verified using numerical and laboratory sensitivity experiments. The numerical simulations suggest that only 3%-23% of the dense water enters the coastal pathway, and the percentage depends highly on the ratio of the velocities of the offshore and coastal plumes. This makes the velocity ratio potentially useful for observational studies to assess the amount of dense water formed in coastal polynyas. [ABSTRACT FROM AUTHOR]

The carcasses of large pelagic vertebrates that sink to the seafloor represent a bounty of food to the deep-sea benthos, but natural food-falls have been rarely observed. Here were report on the first observations of three large ‘fish-falls’ on the deep-sea floor: a whale shark (Rhincodon typus) and three mobulid rays (genus Mobula). These observations come from industrial remotely operated vehicle video surveys of the seafloor on the Angola continental margin. The carcasses supported moderate communities of scavenging fish (up to 50 individuals per carcass), mostly from the family Zoarcidae, which appeared to be resident on or around the remains. Based on a global dataset of scavenging rates, we estimate that the elasmobranch carcasses provided food for mobile scavengers over extended time periods from weeks to months. No evidence of whale-fall type communities was observed on or around the carcasses, with the exception of putative sulphide-oxidising bacterial mats that outlined one of the mobulid carcasses. Using best estimates of carcass mass, we calculate that the carcasses reported here represent an average supply of carbon to the local seafloor of 0.4 mg m−2d−1, equivalent to ∼4% of the normal particulate organic carbon flux. Rapid flux of high-quality labile organic carbon in fish carcasses increases the transfer efficiency of the biological pump of carbon from the surface oceans to the deep sea. We postulate that these food-falls are the result of a local concentration of large marine vertebrates, linked to the high surface primary productivity in the study area. [ABSTRACT FROM AUTHOR]

Anthropogenic litter is present in all marine habitats, from beaches to the most remote points in the oceans. On the seafloor, marine litter, particularly plastic, can accumulate in high densities with deleterious consequences for its inhabitants. Yet, because of the high cost involved with sampling the seafloor, no large-scale assessment of distribution patterns was available to date. Here, we present data on litter distribution and density collected during 588 video and trawl surveys across 32 sites in European waters. We found litter to be present in the deepest areas and at locations as remote from land as the Charlie-Gibbs Fracture Zone across the Mid-Atlantic Ridge. The highest litter density occurs in submarine canyons, whilst the lowest density can be found on continental shelves and on ocean ridges. Plastic was the most prevalent litter item found on the seafloor. Litter from fishing activities (derelict fishing lines and nets) was particularly common on seamounts, banks, mounds and ocean ridges. Our results highlight the extent of the problem and the need for action to prevent increasing accumulation of litter in marine environments. [ABSTRACT FROM AUTHOR]

Sinking dense plumes are important in many oceanographic settings, notably the polar formation of deep and bottom waters. The dense water sources feeding such plumes are commonly affected by tidal modulation, leading to plume variability on short time scales. In a simple unsteady theory of one-dimensional plumes (based on conservation equations for volume, momentum, and buoyancy), this plume variability is manifested as waves that travel down the resulting current. Using numerical techniques applied to the hyperbolic conservation equations, this study investigates the novel concept that these waves may break as they travel down the plumes, triggering intense local mixing between the dense fluid and surrounding ocean. The results demonstrate that the waves break at geophysically relevant distances from the plume source. The location of wave breaking is very sensitive to plume drag from the seabed, the properties of the dense source, and the amplitude and period of the source modulation. To the extent that the simple model represents the real world, these results suggest that wave breaking originating from the tidal modulation of dense plumes could lead to a strong and previously unexplored source of local deep-ocean mixing. [ABSTRACT FROM AUTHOR]

Abstract: Detecting unconventional seismic signals related to subduction zone processes at depth in continuous ocean bottom seismometer (OBS) records requires the analysis and identification of noise due to instrumental problems, deployment sites or sea state conditions. The temporary OBS deployment at the Lesser Antilles subduction zone provides new insights into the feasibility of detecting unconventional signals such as non volcanic tremor (NVT), long-period (LP) or ultra-long period (ULP) events. Analysis of noise at an array comprising several sites and types of instruments and comparison with recordings on land shows transients in the noise. Episodes can be identified considering the diversity of sites and instrument types and comparing the seismic signals with meteorological and oceanographic data. In order to reliably detect NVT (1–10Hz) originating from inside the solid Earth, one must first characterize noise induced by the activity of the atmosphere and hydrosphere at the sea-bottom as well as on land. The semidiurnal modulation of noise amplitude can be shown here not to be due to that of the NVT from a seismic source at depth which is related to the subduction interplate and whose activity is modulated by the tidal stresses as inferred for other megathrusts on emerged forearcs. Here, the semidiurnal modulation is rather due to the effect of the tides themselves, such as tidal currents, since they do not affect all types and all components of the unique multi-station array of OBS that could be deployed on this submerged forearc. The short period cut-off of the strong noise due to ocean surface infragravity waves increases to longer periods with OBS depth, thereby increasing the observational window with low noise to lower frequencies, and deep OBS sites may be advantageous for detecting LP events. [Copyright &y& Elsevier]

Abstract: Open-ended pipe piles are commonly driven into the seabed to support offshore platforms. This paper presents a case of practical offshore driven pile installation experiences associating with premature refusal. Pile drivability and capacity are analyzed using sufficient driving records. Dynamic loading tests were performed three months after the driving in order to determine the pile capacity after refusal. The test results are detailed in this paper compared with back analysis of measured pile driving records. Empirical equations are provided to predict soil resistance during driving and after setup according to the driving records and dynamic loading tests. Analyzing this practical engineering case is hoped to lead to a better understanding of pile driving, especially when premature refusal occurs. The sufficient details of the engineering data in this paper are also expected to enrich the engineering experience and literature of offshore piles in offshore engineering. [Copyright &y& Elsevier]

The direction normal to the Earth spherical (or ellipsoidal) surface is not vertical (called deflected vertical) since the vertical direction is along the true gravity g (= i g λ + j g φ + k g z). Here, (λ , φ , z) are (longitude, latitude, depth), and (i , j , k) are the corresponding unit vectors. The spherical (or ellipsoidal) surfaces are not horizontal surfaces (called deflected-horizontal surfaces). The most important body force g (true gravity) has been greatly simplified without justification in oceanography to the standard gravity (-g 0 k) with g 0 = 9.81 m/s2. Impact of such simplification on ocean dynamics is investigated in this paper using the Ekman layer model. In the classical Ekman layer dynamic equation, the standard gravity (-g 0 k) is replaced by the true gravity g (λ , φ , z) with a constant eddy viscosity and a depth-dependent-only density ρ (z) represented by an e-folding near-inertial buoyancy frequency. New Ekman spiral and in turn new formulae for the Ekman transport are obtained for ocean with and without bottom. With the gravity data from the global static gravity model EIGEN-6C4 and the surface wind stress data from the Comprehensive Ocean-Atmosphere Data Set (COADS), large difference is found in the Ekman transport using the true gravity and standard gravity. • True gravity g (λ , φ , z) represents vertical and has latitudinal and longitudinal components. • Replacement of the standard gravity -g 0 k by g (λ , φ , z) in the classical ocean Ekman layer equation leads to a new solution. • With data from EIGEN-6C4 and COADS, the ocean Ekman transport is much larger due to g (λ , φ , z) than due to surface wind stress. • Replacement of geopotential associate with -g 0 k by associate with g (λ , φ , z) may drastically impact physical oceanography. [ABSTRACT FROM AUTHOR]

The structure of northerly overflow of Antarctic Bottom Water (AABW) through passages in the East Azores Ridge (37° N) in the East Atlantic from the Madeira Basin to the Iberian Basin is studied on the basis of hydrographic measurements carried out by the Institute of Oceanology, Russian Academy of Sciences (RAS) in October 2011, historical World Ocean Data Base 2009, and recent data on the bottom topography. The overflow of the coldest layers of this water occurs through two passages with close depths at 16° W (Discovery Gap) and at 19°30′ W (nameless Western Gap). It is shown that it is likely that the role of the latter passage in water transport was underestimated in earlier publications because the water (2.01°C) found in the region north of the Western Gap was cooler than in the region north of the Discovery Gap (2.03°C). In 2011, we found a decrease of 0.01°C in the AABW temperature near the bottom compared to previous measurements in 1982 (from 2.011°C to 2.002°C). Analysis of the historical database shows that this decrease is most likely caused by the cooling trend in the abyssal waters in the East Atlantic basins. [ABSTRACT FROM AUTHOR]

Abstract: While there are many generalized schemes representing the biogeographic distribution of life in the deep sea, reviewed here, a comprehensive analysis has not been undertaken since Vinogradova (1979, 1997) for the abyssal and Belyaev (1989) for the hadal. The purpose of this paper is to propose global biogeographic provinces for the lower bathyal and abyssal benthos (>800m depths) in order to aid high seas management efforts. Biological samples from these depths are sparse so delineation of biogeographic provinces was initially hypothesized using oceanographic proxies, and examined with documented locations of select benthic marine species. These biogeographic provinces were first developed in 2009 via an expert consultation workshop to delineate biogeographic provinces in offshore regions – the Global Open Ocean and Deep Sea (GOODS) classification. We have refined the GOODS deep-sea classification by incorporating additional high-resolution hydrographic and organic-matter flux data for the seafloor. Water mass characteristics (temperature and salinity) and particulate organic flux to the seafloor were the strongest determinants in the final delineation of provincial boundaries. This process resulted in the delineation of 14 lower bathyal and 14 abyssal provinces. The bathyal and abyssal classifications presented here should be used with other management tools and analyses (e.g., predictive habitat modeling, seamount classifications, etc.) to help determine where marine protected areas should be placed and to minimize the negative impacts of commercial activities in the high seas. [Copyright &y& Elsevier]

Abstract: The oxygen isotopic composition (δ18O) of planktonic foraminiferal shells in seafloor sediment provides information on past surface oceanography. Knowledge of seasonal and depth habitat, as well as the δ18O disequilibrium (vital effect), is essential to constrain the interpretation of sedimentary δ18O. Here, we present a 1-year time series of planktonic foraminiferal shell fluxes and δ18O from a sediment trap moored in the northwestern margin of the North Pacific. The vital effect and calcification depth for four species were estimated by comparing shell δ18O and the predicted values of equilibrium calcite calculated from temperature and estimated δ18O in seawater. Six major species (Neogloboquadrina incompta, Neogloboquadrina dutertrei, Neogloboquadrina pachyderma, Globigerina quinqueloba, Globigerina bulloides, and Globorotalia scitula) constituted 97% of the total foraminiferal flux. Most major species showed large fluxes in June and December, corresponding to periods of the development and disruption of the seasonal thermocline, implying the importance of nutrient injection and/or circulation for foraminiferal fluxes. Additional peaks in N. dutertrei and N. pachyderma were observed in August. The seasonal successions of foraminiferal fluxes corresponded to surface ocean stratification conditions and food availability, which are closely related to circulation of local currents. Vital effect estimations suggest that shells calcified in equilibrium for G. bulloides and N. pachyderma [sinistral (s)] and with a −0.7‰ offset for N. dutertrei [dextral (d)], a −1.0‰ offset for N.incompta (d), and a −0.3‰ offset for N. pachyderma (d). The calculation of flux-weighted δ18O values reveals that the sedimentary δ18O values of G. bulloides, N. dutertrei (d), and N. incompta (d) reflect surface temperature in winter season, and those of N. pachyderma (s) and N. pachyderma (d) reflect summer and annual mean subsurface temperature, respectively. The shallow calcification depths for the four species suggest that δ18O between different species (Δδ18O) in the western North Pacific does not work for reconstructing past stratification conditions, unlike in other regions. Rather, the Δδ18O between N. pachyderma (s) and G. bulloides, N. dutertrei (d) or N. incompta (d) may be a more suitable proxy for past seasonality. [Copyright &y& Elsevier]

Abstract: Chilean fjords are the lowest latitude at which glaciers reach the sea today. High accumulation and mass throughput sustain tidewater glacier margins in this relatively mild climatic and oceanographic setting. 27,000 km2 of swath bathymetry allow mapping of sea-floor landforms and inferences on glacimarine sediments and sedimentation. Tidewater glaciers are present in several fjords. Beyond retreating Tempano glacier, a terminal moraine marks the limit of probable Little Ice Age advance with smaller transverse ridges closer to the glacier. Beyond advancing Pio XI Glacier there are few signs of organised submarine landforms. Older moraine ridges along several fjords formed at still-stands during deglaciation. Elsewhere, meltwater-fed braided rivers connect the glacial and marine sedimentary systems. Swath imagery shows glacifluvial and fluvial deltas with small channels and chutes that develop into long and sinuous turbidity-current channels. Few iceberg ploughmarks and submarine slope failures were observed, but several fields of pockmarks were present. The fjords of Chile are dominated by sediment delivery from turbid meltwater which distributes fine-grained debris widely, producing sorted and laminated fine-grained ice-proximal wedges and draping ice-distal seismic architecture to give a predominantly smooth sea floor. Turbidity currents also transfer sediments to some ice-distal environments. The Chilean fjordlands represent the mildest climatic and oceanographic end-member of a continuum of glacier-influenced marine settings; similar to south-east Alaska in the northern hemisphere. Components of a landform-assemblage model for climatically mild meltwater-dominated fjords include ice-contact moraine ridges, glacifluvial and fluvial deltas, and turbidity-current channels. Full-glacial and deglacial streamlined subglacial landforms are likely to have been buried in many areas by subsequent glacimarine sedimentation. [Copyright &y& Elsevier]

Abstract: We use a numerical model to examine the dynamics controlling flushing of the basins of the Orust fjord system on the Swedish west coast over a period of 71days in the autumn of 2010. This fjord system is known for its seasonal and permanent hypoxic basins; Koljöfjord, Byfjord and Havstensfjord. It is shown that wind direction determines in- and outflows of the basins. Westerly winds result in surface currents towards the interior of the system, and counter currents at the bottom. In contrast, easterly winds cause the export of surface water, which is compensated by upwelling of Skagerrak water. Although these easterly winds cause renewal to take place several times a month in southern Havstensfjord, it occurs only once or twice in the northern part, while Koljöfjord and Byfjord are ventilated about every 3years. The reduction in density throughout the water column (i.e. weakening of the vertical stratification) is related to the amount of energy being supplied to the deepwater by internal waves, created by barotropic tides across the sills, and wind blowing across the surface. The model shows that, in the southern part of the system, tidal movement dominates the energy supply to the deepwater. Further into the system, the importance of wind energy increases. In Koljöfjord and Byfjord, wind accounts for about 40% of the supplied energy for deepwater mixing. Concurrent weekly measurements taken in each fjord basin reveal that the monthly monitoring programme currently in place cannot adequately resolve the dynamics of the fjords. Modelled and observed currents in Svanesund and Sunninge Strait show prominent baroclinic motion on time-scales between one day and one week, suggesting that monitoring programs that aim to support numerical modelling need to resolve these time scales. [Copyright &y& Elsevier]

The impact of small-scale topography on the ocean's dynamical balance is investigated by quantifying the rates at which internal wave drag extracts (angular) momentum and vorticity from the general circulation. The calculation exploits the recent advent of two near-global descriptions of topographic roughness on horizontal scales on the order of 1-10 km, which play a central role in the generation of internal lee waves by geostrophic flows impinging on topography and have been hitherto unresolved by bathymetric datasets and ocean general circulation models alike. It is found that, while internal wave drag is a minor contributor to the ocean's dynamical balance over much of the globe, it is a significant player in the dynamics of extensive areas of the ocean, most notably the Antarctic Circumpolar Current and several regions of enhanced small-scale topographic variance in the equatorial and Southern Hemisphere oceans. There, the contribution of internal wave drag to the ocean's (angular) momentum and vorticity balances is generally on the order of ten to a few tens of percent of the dominant source and sink terms in each dynamical budget, which are respectively associated with wind forcing and form drag by topography with horizontal scales from 500 to 1000 km. It is thus suggested that the representation of internal wave drag in general circulation models may lead to significant changes in the deep ocean circulation of those regions. A theoretical scaling is derived that captures the basic dependence of internal wave drag on topographic roughness and near-bottom flow speed for most oceanographically relevant regimes. [ABSTRACT FROM AUTHOR]

Georges Bank is a large, shallow feature separating the Gulf of Maine from the Atlantic Ocean. Previous studies demonstrated a strong tidal-mixing front during the warm season on the northern bank margin between thermally stratified water in the Gulf of Maine and mixed water on the bank. Tides transport warm water off the bank during flood tide and cool gulf water onto the bank during ebb tide. During 10 days in August 2009, we mapped frontal temperatures in five study areas along ∼100 km of the bank margin. The seabed “frontal zone”, where temperature changed with frontal movment, experienced semidiurnal temperature maxima and minima. The tidal excursion of the frontal boundary between stratified and mixed water ranged 6 to 10 km. This “frontal boundary zone” was narrower than the frontal zone. Along transects perpendicular to the bank margin, seabed temperature change at individual sites ranged from 7.0°C in the frontal zone to 0.0°C in mixed bank water. At time series in frontal zone stations, changes during tidal cycles ranged from 1.2 to 6.1°C. The greatest rate of change (−2.48°C hr−1) occurred at mid-ebb. Geographic plots of seabed temperature change allowed the mapping of up to 8 subareas in each study area. The magnitude of temperature change in a subarea depended on its location in the frontal zone. Frontal movement had the greatest effect on seabed temperature in the 40 to 80 m depth interval. Subareas experiencing maximum temperature change in the frontal zone were not in the frontal boundary zone, but rather several km gulfward (off-bank) of the frontal boundary zone. These results provide a new ecological framework for examining the effect of tidally-driven temperature variability on the distribution, food resources, and reproductive success of benthic invertebrate and demersal fish species living in tidal front habitats. [ABSTRACT FROM AUTHOR]

Abstract: The two main observations characterising marine and lacustrine methane macro-seeps are ebullition through holes in the sea- or lake-bed, and hydroacoustic “flares” in the water column. This paper reviews multi-year, multi-scale, and multi-discipline results from three seep locations in the North Sea and combines the knowledge with recent seafloor and water column results from seeps in the Santa Barbara basin, California, a seep off West Africa, seeps in the Gulf of Mexico, and in Lake Baikal, Russia. We have identified a total of 12 characteristics of methane and minor oil macro-seeps that are not only geological in nature, but also biological and geochemical. These are shown to impact the marine environment in different ways, not least in benefactory manners, as primary producers (mainly bacteria and archaea) tend to bloom during seepage. Therefore, the seepage is inferred to have a fertilizing effect on both the seafloor and the water column, which may be of broad ecological and biological significance. The study concludes with a holistic conceptual seep-model which is expected to be of interest to a broad range of researchers in the fields of oceanography and limnology. [Copyright &y& Elsevier]

Abstract: Recruitment of Aristeus antennatus over the species'' entire depth range and distribution area in the Mediterranean Sea is described. Because of the dearth of information on the recruitment of deep-sea species in the literature, the findings reported here take on special significance. Samples were collected at depths between 900 and 2800m on seven trawl surveys using three samplers: an OTMS trawl, an Agassiz bottom frame trawl, and a Macer-Giroq suprabenthic sledge, computing a total of 80, 26 and 14 trawls, respectively. Early juveniles (≤15mm CL) were observed to be present down to a depth of 2800m and to attain maximum percentage abundance between 1350 and 2000m. Spring was the season of peak abundance for juveniles. Several hypotheses explaining this deep-sea recruitment are discussed, including oceanographic events coupled with enrichment of the bathyal bottoms and competitive exclusion in deep-sea species. Studying the deep-sea recruitment of A. antennatus contributes to our understanding of the species'' life history and supplies knowledge essential to proper management and sustainable exploitation of the species. [Copyright &y& Elsevier]

Abstract: Density and average size of two species of abyssal sponges were analyzed at Station M (∼4100m depth) over an 18-year time-series (1989–2006) using camera sled transects. Both sponge taxa share a similar plate-like morphology despite being within different families, and both showed similar variations in density and average body size over time, suggesting that the same factors may control the demographics of both species. Peaks in significant cross correlations between increases in particulate organic carbon flux and corresponding increases in sponge density occurred with a time lag of 13 months. Sponge density also fluctuated with changes in two climate indices: the NOI with a time lag of 18 months and NPGO with a time lag of 15 months. The results support previous suggestions that increased particulate organic carbon flux may induce recruitment or regeneration in deep-sea sponges. It is unknown whether the appearance of young individuals results from recruitment, regeneration, or both, but the population responses to seasonal and inter-annual changes in food supply demonstrate that sponge populations are dynamic and are capable of responding to inter-annual changes despite being sessile and presumably slow-growing. [Copyright &y& Elsevier]

Abstract: Photographic quadrat sampling is commonly used for the study of sessile benthic communities. However, photoquadrat data handling is fragmented into several processing methods, and there is a scarcity of dedicated software tools that integrate all major analysis options. photoQuad is a new software system for advanced image processing of photographic samples, dedicated to ecological applications. The software integrates a series of methods for the extraction of species area, percentage coverage, or presence/absence information, including random point counts (RP), grid cell counts (CL), freehand regions (FH), and image segmentation-based regions (SG). These are simultaneously functional in a layer-based environment, further supported by a variety of tools for image enhancement, image calibration, automatic quadrat boundary detection, and management of user-specific species libraries. The paper documents the main features of photoQuad, and demonstrates its performance through the simultaneous application of the RP, CL, FH, and SG methods on identical datasets, and the comparison of errors in species area and coverage measurements. The simulated data used for reference are disk-shaped patches, whose area and density statistics are equivalent to three benthic species characteristic of Mediterranean coralligenous communities. The analysis indicated that measurement methods differed in area and coverage bias, as well as in their sensitivity to species size. Large patches were accurately measured by all methods in terms of mean scaled error, but CL and RP provided high error variance, and their performance deteriorated with decreasing patch size; the region-based SG and FH methods provided the lowest errors and were both robust to patch size. The image and quadrat calibration process showed no statistically significant effect on the outputs, although further analysis is needed to validate this result. Overall, photoQuad constitutes a powerful software for elaborate analysis of photoquadrat images, facilitating fast and comparable evaluation of the ecological information contained therein. The photoQuad software is freely available to download and use from: http://www.mar.aegean.gr/sonarlab/photoquad. [Copyright &y& Elsevier]