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Early life history traits of small pelagic fish are usually affected by environmental conditions. Patagonian sprat, Sprattus fuegensis, is a small pelagic fish that inhabits the continental shelf, fjords and channels of Patagonia. Their larvae are usually exposed to large variations in physical and biological conditions. We evaluated the effects of environmental conditions on early life history traits of this key species encompassing over 20 years of information. The characterization of oceanographic features, larval abundance and distribution was carried out in western Patagonia between 1996 and 2019, while the growth and mortality rates were estimated for the austral spring 2019 between 49°54′S and 53°55′S. Larval abundance decreased three to ten times from 1996 to 1997 to the rest of the study period (2008–2010 and 2014–2019), with larger abundances being found over the shelf. In spring 2019, the growth rate was 0.20 ± 0.05 mm d−1 for larvae between 9 and 19 days after hatching. The growth rate was similar in partially stratified (7–50 J m−3) and stratified waters (50–100 J m−3), but slower in mixed waters (< 7 J m−3). GAM modelling showed that the faster larval growth occurred in partially stratified waters with temperatures above 7.5°C. Natural mortality rates were higher in partially stratified waters (24% of daily loss), lower in stratified areas (14%) and the lowest in the mixed water column (12%). Accordingly, larvae living in channels had faster growth rates but higher daily mortality, while those that hatched or were advected to water parcels on the continental shelf had slower growth but lower daily mortality. Finally, these latter traits may be an example of an inverse growth‐selective survival strategy. [ABSTRACT FROM AUTHOR]

For many years, parasite ecologists have debated the relative importance of phylogeny and ecology as drivers of parasite community structure. Here, we address this issue using data on the metazoan ectoparasite communities of different flatfish species. Twenty species of flatfish were collected along the continental shelf of the Southern Gulf of Mexico and examined for ectoparasites. Eight flatfish species were parasitized by at least one ectoparasite species. In total, 326 ectoparasites, representing 11 species (4 monogeneans, 4 copepods, 1 isopod, 1 branchiurid, and 1 leech) were removed from 1622 hosts examined. The highest prevalence (37.5%) occurred in Bomolochus sp1 from Trinectes maculatus, while the lower (0.1%) for Argulus sp., Gnathia sp. and Trachellobdella lubrica from Cyclopsetta chittendeni. Changes in the ectoparasite community structure per host species and region were evaluated using a Permutational Multivariate Analysis of Variance and represented by a multidimensional scaling analysis. Significant differences in the parasite species composition among regions and hosts were detected, but no significant interaction between regions and hosts occurred. A multivariate pairwise t-test detected significant differences in the parasite infracommunities between the Yucatan Shelf and the other two regions; in addition, significant differences were detected between C. chittendeni and the Syacium species as well as between Ancylopsetta dilecta and Syacium papillosum. In this case, there is no relationship between the patterns of ectoparasitic community structure and the inherent phylogenetic affinity of the hosts; instead, the variations in ectoparasitic communities are determined by a regional ecological component. [ABSTRACT FROM AUTHOR]

Unprecedented catastrophic damage to coastal fisheries attributable to harmful Karenia outbreaks were reported in Pacific coastal shelf waters off the southern coast of Hokkaido from late summer to autumn in 2021. To understand the spatiotemporal variability of the Karenia blooms, we analyzed Sentinel 3-derived abundances of Karenia spp. together with marine environmental variables. Karenia spp. were very widely distributed over a maximum of more than 400 km along the shelf from the easternmost Pacific coast of Hokkaido to Cape Erimo, where there was a nearly stable water-mass front, to the west, where pure subtropical water inhibited the westward expansion of Karenia spp. blooms. The duration of the appearance of Karenia spp. at a fixed point was very long--about 45 days--in the middle part of the shelf. East of the Tokachi River, the timeaveraged abundances of Karenia spp. were robustly correlated with the timeaveraged alongshore velocity and stability of the Coastal Oyashio, a coastal boundary current; more intense and stable alongshore currents were associated with less developed Karenia spp. blooms. Time-averaged abundances of Karenia spp. were the highest in the middle part of the shelf, west of the Tokachi River, where low-salinity water from the river suppressed the development of the surface winter mixed layer and might have fostered favorable growth conditions and supplied nutrients of land origin. During the period of Karenia spp. blooms, abundances changed rapidly on a small scale (typically, ≤2 days and ≤50 km) in association with physical-biochemical coupled submesoscale variations. Subsampling of these variations of Karenia spp. abundances at 1-day intervals showed that the maxima and center of gravity of Karenia spp. abundances moved slowly westward along the coast at a typical velocity of 4 cms1. This velocity was one-third that of the time-averaged alongshore velocity of the Coastal Oyashio. Particle-tracking experiments implied that horizontal advection by the Coastal Oyashio, which supplied Karenia spp. eliminated from the upstream shelf to the downstream shelf, contributed to the long duration of Karenia spp. blooms on the middle part of the shelf. [ABSTRACT FROM AUTHOR]

AbstractUnder the 1920 Treaty concerning the archipelago of Spitsbergen (Svalbard Treaty), the contracting parties recognize the full and absolute sovereignty of Norway over the archipelago. The sovereignty is to be exercised subject to the stipulations of the Treaty, which include equal rights of the contracting parties to fish and hunt on the territory of Spitsbergen and its territorial waters. Consistent with the developments of the law of the sea, Norway has claimed sovereign rights over the continental shelf and established 200 nautical miles (NM) zones off its coast, including Svalbard. Norway established a 200 NM Fisheries Protection Zone off the coast of Svalbard. Several contracting parties claim that the equal rights under the Svalbard Treaty are applicable in the maritime zones claimed or established after 1920. This is disputed by Norway by referring to the wording of the Treaty, which stipulates that it is applicable within the 12-NM territorial waters. Owners and captains of vessels flagged in other contracting parties have protested and argued that the arrest and prosecution for illegal fishing in the 200-NM zone off Svalbard violated their equal rights of fishing. The Court had not addressed the question of the applicability of the Treaty provisions until 2023. In a civil case before the Supreme Court, a Latvian shipowning company argued that the snow crab regulations on the continental shelf in the Barents Sea were void as they violated the equal rights of contracting parties under the Svalbard Treaty to fish on the continental shelf. The Supreme Court concluded that the treaty provisions were not applicable beyond the 12-NM territorial sea of the archipelago. An attempt by the same company at international litigation through investment arbitration was also unsuccessful. As the dispute issue is settled within the Norwegian legal system, the dispute enters into a new phase. [ABSTRACT FROM AUTHOR]

The paleoenvironmental evolution of the Abrolhos Depression (AD) on the southern Abrolhos Shelf during the global post-Last Glacial Maximum (LGM) transgression is investigated through benthic foraminifera analysis. Downcore sediment samples (core DA03A-5B) collected at a depth of 63 m provide insights into the formation and paleoenvironmental variations of AD over the past 18 kyr BP. The core is divided into four biofacies based on foraminifera assemblages. At the base, the presence of carbonate concretions indicates a karstic surface, marking the initiation of the paleolagoon formation at approximately 13 kyr BP with low density of foraminifera, where species such as Elphidium sp. and Hanzawaia boueana (EH Biofacies) were more abundant. During the Younger Dryas (YD) (12.8–12.5 kyr BP), the AD exhibits two distinct phases: an initially confined lagoon environment with reduced circulation characterized by the dominance of the species Ammonia tepida (At Biofacies), followed by increased circulation characterized by higher density, richness, and diversity of benthic foraminifera. The end of the YD is identified by a significant biofacies change, indicative of a shallow marine environment, where the dominant species were A. tepida and Elphidium excavatum (AE Biofacies), supported by sedimentological and geochemical proxies. This paleoenvironmental shift is associated with Meltwater Pulse (MWP) -1B, suggesting a connection to a shallow marine environment. As sea levels continue to rise, the AD transitions into an open marine setting. However, around 8 kyr BP, a change occurs with the absence of A. tepida and the occurrence of planktonic and other benthic foraminifera typical of the outer shelf, indicating depths greater than 50 m (HQ Biofacies). The findings highlight the complex interplay between climate fluctuations, sea-level changes, and the formation of coastal environments during the LGM transgression. This study contributes to our understanding of paleoenvironmental dynamics, adding valuable insights to the evolutionary history of AD. The results emphasize the importance of integrating benthic foraminifera analysis, radiocarbon dating, and geochemical proxies to reconstruct paleoenvironments accurately. Overall, this research enhances our knowledge of global continental shelf evolution during the post-LGM transgression and provides valuable information for future paleoenvironmental studies. [ABSTRACT FROM AUTHOR]

Shallow-sea environmental variations in the eastern Arabian Sea (EAS) have been related to monsoon variability, poorly ventilated intermediate water, and primary productivity changes. To understand these conditions, benthic foraminiferal assemblages, oxygen isotope ratios, and total organic carbon content have been examined in sediment Core SK291/GC13 from the EAS. We aim to retrieve decadal to centennial time-scale changes in past oxygenation and paleoproductivity during the last 7400 calibrated years before the present (cal yr BP). Our proxy data suggest that the oxic benthic foraminifera species were dominant during ∼7400–6000 cal yr BP. The change from oxic to dysoxic occurred during ca. 6000–3500 cal yr BP, and transition from dysoxic to suboxic environmental conditions happened at ca. ∼3500 cal yr BP. These changes are contemporaneous with weakening of the Indian summer monsoon beginning at ∼5500 cal yr BP which culminated into a major arid phase so-called ca 4.2 ka event in the Indian subcontinent. The EAS experienced low productivity during the early phase of our studied interval (∼7400–6000 cal yr BP) and higher productivity in the middle Holocene (6000–3000 cal yr BP), as revealed by the total organic carbon and benthic assemblages. Furthermore, productivity increased in the warm period and decreased in the Little Ice Age on a decadal scale. The spectral analysis of total organic content and suboxic species indicates a 23-year Hale (solar) cycle during the last millennium, indicating a close relationship between solar activity and monsoon variability. The strengthening of the El Nino-Southern Oscillation perhaps amplified due to increased solar activity in the last millennium, which influenced the climate of the EAS. The study highlights paleo-oxygenation shifts based on benthic foraminiferal assemblages, which are crucial for understanding changes in the oxygen minimum zones (OMZs) and their potential impacts on marine ecosystems. [ABSTRACT FROM AUTHOR]

The Agulhas Current is a globally important western boundary current that influences numerous processes (e.g., upwelling, biogeochemical fluxes and distribution of marine taxa) in the southwestern Indian Ocean. The oceanographic processes of the Agulhas Current are well understood, but precisely how they influence coastal ecosystem productivity remains to be elucidated. In the present foundational study, we characterized the bacterial (16S rRNA gene) and phytoplankton (chloroplast 16S rRNA, rbcL, and eukaryotic 18S rRNA genes) community structures of the Agulhas Current system using a metabarcoding approach. All four markers provided consistent data on the bacterial and phytoplankton communities in the Agulhas Current and coastal sites. The study revealed distinct, conserved communities and similar patterns of dominance by taxa adapted to oligotrophic conditions within the Agulhas Current, sampled 2 yr apart. By contrast, there was significant variability in taxonomic diversity and abundance of phytoplankton communities in the adjacent coastal waters that could be linked to localized upwelling. While the Agulhas Current bacterial and phytoplankton communities were diverse and represented many functional groups, the coastal sites were more diatom‐dominated and included genera typically associated with upwelling, for example, Thalassiosira spp. Based on their relative abundance profiles, phytoplankton communities were more responsive to environmental variability than bacteria and may therefore prove more useful in linking ecosystem dynamics to environmental variability in marine systems. [ABSTRACT FROM AUTHOR]

Jeju Volcanic Island is the largest island in South Korea and is considered a continental shelf intraplate volcanic island. In this study, MELTS, a powerful program for modeling magmatic evolution processes, was applied to simulate the fractional crystallization process of the low-alumina alkaline volcanic rock suite on Jeju Island. MELTS modeling was conducted at many isobaric pressures ranging from 2.0 GPa to 0.1 GPa, different oxygen fugacities (fO2) from FMQ-3 to FMQ + 3, and different H2O contents. The results demonstrate that the most suitable fractionation model for the Jeju low-alumina alkaline magma involves a pressure of 0.2 GPa to 0.1 GPa and an oxygen fugacity close to the FMQ buffer. Additionally, an H2O content of 0.5 wt.% is the most consistent with the evolution trend and mineral composition of the natural rock suite on Jeju Island. Although MELTS possesses several limitations in terms of the stability of calibration, such as spinel overestimation and a lack of experiments on hydrous minerals (which should be improved), MELTS performs well in terms of temperature and pressure prediction and in terms of the assessment of other factors of the fractional crystallization process on Jeju Island. Consequently, to evaluate a magmatic process in a particular region, MELTS should be combined with other analyses and not relied upon independently. [ABSTRACT FROM AUTHOR]

The across‐shore transport of meroplanktonic larvae is predominantly driven by coastal physical processes, resulting in episodic recruitment of benthic species. Historically, due to the sampling challenges associated with resolving these advective mechanisms across the continental shelf, relevant components of larval transport have been difficult to isolate and understand. We use three‐dimensional temperature and velocity data from an array of 29 moorings to identify fundamental physical processes that could have generated successful across‐shore transport and settlement of meroplankton. The dense spatial and temporal sampling from this array allows us to use Lagrangian particle tracking to estimate the influences of wind conditions and the internal tide on the across‐shore transport of planktonic larvae. Settlement was found to be episodic at all depths studied. Above mid‐water, modeled larvae were successfully transported onshore by the internal tide during wind relaxations. Surprisingly, abundant pulses of shallow‐water larvae were supplied to the coast on occasions when strong, upwelling‐favorable winds (> 4 m s−1) drove offshore‐flowing surface waters, revealing a complex, potentially topographically influenced flow. These intense upwelling‐favorable winds also contributed to subsurface onshore flows that created large pulses of larval settlement in deeper waters (> 20 m). Our analyses from this highly resolved data set provide novel insights into the interactions of physical drivers in creating episodic pulses of coastal larval recruitment. [ABSTRACT FROM AUTHOR]

This report provides an overview of contemporary scholarship on the political geographies of oceans. While oceans were overlooked for many years as theories of sovereignty, territory, and borders focused on terrestrial politics, the significant impact of climate change resulted in a new focus on the role oceans place in global environmental and political systems. At the same time, the enclosure of over 40 percent of the oceans as territorial seas, exclusive economic zones, and extended continental shelves through the Convention on the Law of the Sea produced burgeoning literature on maritime borders and conflicts. The report proposes the concept of blue geopolitics to capture an oceanic turn in political geography theories. [ABSTRACT FROM AUTHOR]

The Coastal Ice Ocean Prediction System for the East Coast of Canada (CIOPS-E) was developed and implemented operationally at Environment and Climate Change Canada (ECCC) to support a variety of critical marine applications. These include support for ice services, search and rescue, environmental emergency response and maritime safety. CIOPS-E uses a 1/36° horizontal grid (~ 2 km) to simulate sea ice and ocean conditions over the northwest Atlantic Ocean and the Gulf of St. Lawrence (GSL). Forcing at lateral open boundaries is taken from ECCC's data assimilative Regional Ice-Ocean Prediction System (RIOPS). A spectral nudging method is applied offshore to keep mesoscale features consistent with RIOPS. Over the continental shelf and GSL, the CIOPS-E solution is free to evolve according to the model dynamics. Overall, CIOPS-E significantly improves the representation of tidal and sub-tidal water levels compared to ECCC's lower resolution systems: RIOPS (~ 6 km) and the Regional Marine Prediction System – GSL (RMPS-GSL, 5 km). Improvements in the GSL are due to the higher resolution and a better representation of bathymetry, boundary forcing and dynamics in the upper St. Lawrence Estuary. Sea surface temperatures show persistent summertime cold bias, larger in CIOPS-E than in RIOPS, as the latter is constrained by observations. The seasonal cycle of sea ice extent and volume, unconstrained in CIOPS-E, compares well with observational estimates, RIOPS and RMPS-GSL. A greater number of fine-scale features are found in CIOPS-E with narrow leads and more intense ice convergence zones, compared to both RIOPS and RMPS-GSL. [ABSTRACT FROM AUTHOR]

Aim: Geographic range shifts are a common species' response to climate change. While occurrence data are commonly used to estimate species' geographical range shifts, ongoing debate suggests that local abundance data may be increasingly important for the estimates, but few studies have investigated differences between the above two types of data. We aimed to explore whether occurrence and abundance data would result in different patterns of geographic range shifts for marine fishes. Location: Northeast US Continental Shelf, North Sea, and East Bering Sea. Methods: We used bottom trawl datasets since 1968 in the three large marine communities to assess whether data types would affect estimated shifts in marine fish species. The range centroids of individual species were first estimated every year and linear regressions were fitted to estimate shift rates in both longitudinal and latitudinal directions. The average range centroids of the last 5 years were used to compare differences between the data types in species' shifts. We then grouped species by traits to overview species compositions. Results: Significant differences in shift trends between regressions based on annual occurrence‐ and abundance‐based range centroids were found in species' longitudinal shifts, particularly in the Northeast US Continental Shelf and North Sea. Approximately 38.5%–45.9% of fish species in the large marine communities had inconsistent shift directions when estimated by different data types. In comparison with the average range centroids of the last 5 years between the two data types, large changes were identified in the magnitudes of the shift distances towards the east and west. Fish species with inconsistent shifts between the two data types were mostly composed of commercial and demersal species. Main Conclusions: The results provide observed differences over decades and suggest caution on the estimation of species' geographic range shifts using occurrence and abundance data and highlight the differences for future assessments of marine species shifts under climate change. [ABSTRACT FROM AUTHOR]

The document is an index of editorial contents for Volume 47 of the Journal of Petroleum Geology, published in 2024. It includes articles on various topics such as the structural style and timing of folds in Iran, lacustrine source rocks in Argentina, the modern oil industry in Iran, the Arabia-Eurasia collision zone in Iran, and the influence of Pleistocene glaciation on petroleum systems in the Barents Sea. The document also lists the authors and referees who contributed to the journal. [Extracted from the article]

This paper provides first information about possible occurrence of the myxosporean genus Kudoa in fish of the World Ocean and, in some cases, in associated freshwater bodies at different depths. An analysis of the theoretically assumed site preference by Kudoa of different habitat depths of their fish hosts in the World Fauna is made for the first time. It is revealed that all species of the myxosporean genus Kudoa can be found in coastal shelf zones, of which 90 species (70.8% of the total) occur exclusively in the shelf zone, and the hosts of 50 Kudoa species (39.4%) live in its shallowest part (down to 50 m). 16 species (12.6%) and 14 species (11%) of this genus can be found at depths from the shelf to 500 meters and 1000 meters, respectively. From 1 to 3 species of Kudoa can be encountered theoretically at 1500 m to 3000 m, which is from 0.8 to 2.4% of all known representatives of these parasites. [ABSTRACT FROM AUTHOR]

An offshore installation is exposed to ship collision risk from in-field and passing vessels. Both categories of collision have occurred on the United Kingdom Continental Shelf (UKCS), and both have the potential to result in catastrophic damage to the installation, although to date only significant consequences have been observed in UK waters. World-wide, catastrophic collisions with installations have occurred resulting in severe damage to vessels and installations, leading to loss of life and environmental damage. This led to the authors investigate the occurrence and reporting of ship to platform collisions on the UKCS 1971–2017. It was found that there were periodic fluctuations in the occurrence of collision accidents. This research analyses the accident trends in order to determine the whether the fluctuations were a regular occurrence and, if so, what was the cause. 511 ship to platform collision incidents between 1971 and 2017 were subject to analysis, in terms of damage classification, the vessel type, month of occurrence and a comparison of the release of regulations with the fluctuation of incidents. Subsequently, this analysis has identified a key trend between the reporting of offshore collision incidents and the release and enforcement of offshore Safety Case regulations. [ABSTRACT FROM AUTHOR]

The correction notice for the article "Novel deep-sea observations reveal twilight zone occurrence for two species of pelagic sharks: the bignose shark Carcharhinus altimus and the silky shark Carcharhinus falciformis" addresses the misidentification of a dusky shark as a bignose shark. The authors acknowledge the challenges in distinguishing between these species and have revised sections of the manuscript to reflect this change. The study provides new depth data for the bignose shark and the silky shark, expanding our understanding of their vertical behavior and highlighting the importance of deep diving behavior for ecosystem connectivity. [Extracted from the article]

Context: Coastal beach environments provide habitats for marine megafauna, including turtles, rays, marine mammals and sharks. However, accessing these variable energy zones has been difficult for researchers by using traditional methods. Aims: This study used drone-based aerial surveys to assess spatio-temporal variation of marine megafauna across south-eastern Queensland, Australia. Methods: Drones were operated at five south-eastern Queensland beaches. Megafauna sightings and key variables including location, month and turbidity were analysed to assess variation across locations. Key results: Overall, 3815 individual megafauna were detected from 3273 flights. There were significant differences in the composition of megafauna assemblages throughout the year and among beaches, with megafaunal sightings in >80% of flights conducted off North Stradbroke Island. Conclusions: Strong temporal presence was found that is congruent with other studies examining seasonality. This supports the use of drones to provide ecological data for many hard-to-study megafauna species and help inform long-term sustainable management of coastal ecosystems. Implications: Results indicated that environmental conditions can influence the probability of sighting marine megafauna during aerial surveys. Studying beach environments by using boat-based methods has been difficult. Drone surveys were used to assess abundance patterns of large marine animals in south-eastern Queensland, Australia. Significant differences in the composition of animal groups were found throughout the year and among locations, with large marine animal sightings in >80% of flights conducted off North Stradbroke Island. This supports the use of drones to provide scientific data for hard-to-study marine species and inform management of coastal ecosystems. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is a crucial limiting nutrient for phytoplankton growth in the ocean. The main source of bioavailable N in the ocean is delivered by N2 -fixing diazotrophs in the surface layer. Since field observations of N2 fixation are spatially and temporally sparse, the fundamental processes and mechanisms controlling N2 fixation are not well understood and constrained. Here, we implement benthic denitrification in an Earth system model (ESM) of intermediate complexity (UVic ESCM 2.9) coupled to an optimality-based plankton–ecosystem model (OPEM v1.1). Benthic denitrification occurs mostly in coastal upwelling regions and on shallow continental shelves, and it is the largest N loss process in the global ocean. We calibrate our model against three different combinations of observed Chl , NO3- , PO43- , O2 , and N*=NO3--16PO43-+2.9. The inclusion of N* provides a powerful constraint on biogeochemical model behavior. Our new model version including benthic denitrification simulates higher global rates of N2 fixation with a more realistic distribution extending to higher latitudes that are supported by independent estimates based on geochemical data. The volume and water-column denitrification rates of the oxygen-deficient zone (ODZ) are reduced in the new version, indicating that including benthic denitrification may improve global biogeochemical models that commonly overestimate anoxic zones. With the improved representation of the ocean N cycle, our new model configuration also yields better global net primary production (NPP) when compared to the independent datasets not included in the calibration. Benthic denitrification plays an important role shaping N2 fixation and NPP throughout the global ocean in our model, and it should be considered when evaluating and predicting their response to environmental change. [ABSTRACT FROM AUTHOR]

The histological changes in the liver, kidney, spleen, and gills of Syacium papillosum from the continental shelf of the Yucatan Peninsula, Gulf of Mexico, and their statistical associations with environmental conditions and pollutants were assessed in 2010, 2011, and 2012. We evaluated the extension and severity of the lesions through a degree of tissue change (DTC), and, with the sum of the number of lesion types within each of their DTC stages, we determined the histological alteration index (HAI). The liver and kidney were the most affected organs, with HAI values > 100. Fish with the most severe damage were observed on the Campeche Bank and the Caribbean Sea, contrasting with those collected from the northern Yucatan continental shelf. The presence of foci cellular alteration and abundant melanomacrophage centers indicated that these flatfishes were chronically exposed to environmental stress factors. Redundancy analyses showed strong associations between HAI values and hydrocarbon and heavy metal concentrations in muscle. Our results provide evidence for the first time of a differential health condition of the Yucatan shelf through the histopathology shown in S. papillosum, establishing the baseline for future monitoring programs in the region. [ABSTRACT FROM AUTHOR]

Movement of sediment along shallow continental shelves is a natural process with wide‐ranging environmental and economic implications, making it of high importance to marine spatial planning efforts in the offshore. Development of marine renewable energy, for instance, requires detailed understanding of the morphodynamics of mobile bedforms to select foundation types and ensure safe installation of infrastructure in shallow shelf environments. This study evaluates geomorphology and sediment mobility of Dogfish Bank (< 20 mbsl) in the Hecate Strait offshore British Columbia, Canada, using hydroacoustic and airborne bathymetric data combined with seismic profiles and grain‐size information. These data reveal current‐swept features ranging from sediment‐depleted lag to sediment‐abundant sand ridges and dunes, with sand ribbons and furrows in‐between. Seismic reflection data show up to 15 m of surficial sand concentrated beneath north‐aligned sand ridges that dominate the bathymetry of northwest Hecate Strait. Sand ribbons (typically understood sediment‐limited features in shallow marine environments) are notably maintained over seabed with comparable sand thickness to adjacent dunes (i.e. sediment‐abundant features), suggesting local spatial variability in hydrodynamics and sediment characteristics (principally grain size) influence expression of mobile bedforms. Repeat mapping between 2008 and 2019 shows dunes and ribbons both migrate northwards, with largest seafloor changes along northeast‐facing lee sides of dunes, matching closely with published models of sediment mobility which suggest northward bedform migration is largely driven by storms. Median total migration distance is 164 m (northward) for dunes (time‐averaged rate of 14.9 m/year). Sand ribbons show less migration (median northward distance of 73 m) and migrate in a depth‐dependent manner. Because sand ribbons are typically flow‐parallel features, their lateral migration likely results from varying current directions and flow acceleration over shallower seabed. Sand ribbon migration should therefore a consideration in studies examining seabed change, particularly when they are formed over unconsolidated sediment. [ABSTRACT FROM AUTHOR]

Rough‐toothed dolphins (Steno bredanensis) typically inhabit deep oceanic waters from tropical to temperate waters worldwide. However, their ecology and behavior remain poorly understood. We investigated site fidelity and social structure of rough‐toothed dolphins using photo‐identification data collected between 2014 and 2022 in the continental shelf waters of the southwestern coast of Mexico. A total of 133 groups of rough‐toothed dolphins were recorded. Mean group size was 4.9 individuals (SD = 4.5), and dolphins were encountered in waters of a mean depth of 110 m (SD = 188). Of 228 individuals identified, 55% were observed once, 39% were seen between two and four times, and 6% were seen five times or more. Site fidelity analysis suggests three levels of site fidelity: transients, occasional visitors, and regular visitors, which are likely to affect the social structure. Through network analysis, nonrandom social patterns were identified (S = 1.25 ± 0.26) and dolphins exhibited both preferences and avoidances of social partners. Cluster analysis suggested significant divisions within the population (Q = 0.43 ± 0.05). Despite limitations related to sample size and design, this preliminary study suggests that rough‐toothed dolphins are best characterized by a fission‐fusion society, which is similar to most coastal delphinid populations. [ABSTRACT FROM AUTHOR]

Glaciomarine fjords dominate the coastal margin of the West Antarctic Peninsula. Studies in similar habitats in the Arctic have shown that benthic biodiversity and ecosystem functioning in inner and middle fjord basins are reduced by turbidity and sedimentation disturbance caused by climate warming–enhanced glacial melting. In contrast, the inner and middle fjord basins along the West Antarctic Peninsula are characterized as productivity and biodiversity hotspots, but benthic ecosystem functions remain unevaluated. In 2015–2016, we conducted sediment respiration and 13C pulse‐chase experiments to assess benthic ecosystem functions along a five‐station transect at ~ 500–600 m depths from the inner Andvord Bay fjord, through to Gerlache Strait, and onto the open continental shelf. Incubation samples from the inner and middle basins of Andvord Bay showed peaks in background seafloor respiration, benthic biomass, and uptake of labeled algal biomass compared to more outlying stations; the continental shelf exhibited the lowest levels of these variables, as well as dissolved inorganic carbon production. Macrofaunal community uptake was responsible for most of the C processing in the inner and middle parts of the fjord (> 45%) while dissolved inorganic carbon was the dominant repository of processed C near the fjord mouth and on the continental shelf (> 80%). The inner parts of Andvord Bay are hotspots of benthic C‐cycling and metabolism, in addition to biodiversity. Ongoing climate warming is likely to negatively impact these inner‐fjord hotspots by increasing meltwater input and sedimentation disturbance, yielding a reduction in the input and recycling of labile detritus at the seafloor in the inner‐middle fjord. [ABSTRACT FROM AUTHOR]

High-resolution seismic imaging allows for the better interpretation of subsurface geological structures. In this study, we employ least-squares reverse time migration (LSRTM) as a seismic imaging method to delineate the subsurface geological structures from the field dataset for understanding the status of Arctic subsea permafrost structures, which is pertinent to global warming issues. The subsea permafrost structures in the Arctic continental shelf, located just below the seafloor at a shallow water depth, have an abnormally high P-wave velocity. These structural conditions create internal multiples and noise in seismic data, making it challenging to perform seismic imaging and construct a seismic P-wave velocity model using conventional methods. LSRTM offers a promising approach by addressing these challenges through linearized inverse problems, aiming to achieve high-resolution, subsurface imaging by optimizing the misfit between the predicted and the observed seismic data. Synthetic experiments, encompassing various subsea permafrost structures and seismic survey configurations, were conducted to investigate the feasibility of LSRTM for imaging the Arctic subsea permafrost from the acquired seismic field dataset, and the possibility of the seismic imaging of the subsea permafrost was confirmed through these synthetic numerical experiments. Furthermore, we applied the LSRTM method to the seismic data acquired in the Canadian Beaufort Sea (CBS) and generated a seismic image depicting the subsea permafrost structures in the Arctic region. [ABSTRACT FROM AUTHOR]

While the biogeochemical properties of the Israeli coastal shelf (ICS) are similar to adjacent pelagic waters, the external sources of inorganic nitrogen (N) are very different. The main source of 'new' N to the pelagic zone is deep winter mixing, with minor contributions from atmospheric deposition and eddy diffusion across the nutricline. For the ICS, major N sources include offshore water advection (260 × 10⁶ mol N y−¹), atmospheric input (115 × 10⁶ mol N y−¹), and riverine input (138 × 10⁶ mol N y−¹), which primarily consists of treated wastewater and stormwater runoff. Direct pollutant discharge from sewage outfalls and submarine groundwater discharge are relatively minor. Key N sinks are new production (420 × 10⁶ mol N y−¹) and sediment deposition and uptake (145 × 10⁶ mol N y−¹). Inputs of nitrate and ammonium were similar and dominant in winter. Unlike temperate shelves, where riverine input is dominant, here it was only slightly higher than atmospheric input, with net N advection onto the shelf being significant. External N inputs did not change net primary production (NPP) by more than ~30% or affect dominant pico and nanophytoplankton genera, except in localized patches. This study offers baseline values for future climate and environmental change assessments. [ABSTRACT FROM AUTHOR]

This article considers some recent jurisprudence in maritime boundary delimitation that results in the creation of ‘grey areas’. Such grey areas have generated uncertainty in practice, specifically concerning claims to entitlements and the rights that States may exercise in such areas. The article reviews the two Bay of Bengal cases (International Tribunal for the Law of the Sea 2012 and the Annex VII Tribunal 2014) and two cases before the International Court of Justice (Somalia v. Kenya 2021; Nicaragua v. Colombia 2023), indicating the need for delimitation of maritime areas and legal rights to reflect the ‘physical reality at the time of delimitation’. [ABSTRACT FROM AUTHOR]

The Canary Current Large Marine Ecosystem (CCLME) is one of the most productive Large Marine Ecosystems worldwide. Assessing the abundance, biomass and distribution of zooplankton in the southern part of this system, off the coast of West Africa, remains challenging due to limited sampling efforts and data availability. However, zooplankton is of primary importance for pelagic ecosystem functioning. We applied an inversion method with combined analysis of acoustic and biological data for copepod discrimination using a bi-frequency (38 and 120 kHz) approach. Large copepods with equivalent spherical radii > 0.5 mm were identified using differences in the mean volume backscattering strength (MVBS). Regarding abundance measured by net sampling, copepods strongly dominated the zooplankton community and the large fraction account for 18%. This estimate correlated significantly with MVBS values that were obtained using an inverse algorithm. We confirmed the utility of using 38 kHz for large copepod detection. An epipelagic biomass of large copepod was estimated at 120–850 mg m-2 in March during upwelling season. It is worth noting that this estimation likely underestimates the true biomass due to inherent uncertainties associated with the measurement method. We recommend future investigations in the interest of using only nighttime data to improve the sampling pattern, particularly on the upper part of the water column (< 10 m) as well as on the shallow part of the continental shelf (< 20 m depth) not covered by fisheries vessel. Nevertheless, such high copepod biomass supports high fish production underlining the key role of copepod in the CCLME. Our results open the way to the analysis of the fluctuation and trend of copepod biomass, along with three decades of fisheries acoustics data available in the region. This helps to determine ecosystem changes, particularly under climate change, and to investigate the role of copepods in the southern CCLME carbon pump at the fine scale. [ABSTRACT FROM AUTHOR]

Sperm whales spatially segregate by sex and social behavior as they mature. In the North Atlantic, male whales move to higher latitudes as far as Svalbard at 80° N, while females and young whales typically remain around lower latitudes below 40–45° N. The Azores, Madeira, and the Canary Islands constitute important nursery grounds for female and young sperm whales. Irish waters represent a midpoint for this species' spatial segregation in the Northeast Atlantic, where the species occurs along the submarine canyon systems to the west of the country. Historically, just male whales were thought to be found in this region between 51 and 55° N, but one adult female was caught by commercial whalers in 1910, and a 5.49 m calf was found stranded in 1916. Between 1995 and 2023, 10 female sperm whales have been stranded around the coast of Ireland. Eight of these whales have been stranded since 2013, and there has been at least one stranding per year between 2019 and 2023. Four of these strandings have occurred in Donegal in the northwest of Ireland, indicating the presence of female whales along the continental shelf off this region. Two females were stranded within a day of each other and were found in similar states of decomposition in February 2022, indicating that they may have been part of the same group rather than being lone vagrant individuals. Sperm whale calves and juveniles were also sighted in Irish waters in 2001, 2004, and 2010 in the Rockall Trough, along the Porcupine Bank and Goban Spur, where between 1 and 3 individuals were observed on four occasions while one calf live stranded in 2004. These records indicate a historical presence of female and young sperm whales in this region but that an apparent increase in occurrence has taken place over the past decade. [ABSTRACT FROM AUTHOR]

The jurisprudence concerning the continental shelf delimitation beyond 200 nautical miles (nm) over the past decade converged on distinguishing delineation from delimitation, which justifies the appropriateness of the judiciary to delimit the continental shelf beyond 200 nm in the absence of the recommendations issued by the Commission on the Limits of the Continental Shelf (CLCS). Mauritius/Maldives decided by a special chamber of the International Tribunal for the Law of the Sea departs from the established jurisprudence. By applying a 'significant uncertainty' standard that puts the relationship between entitlement and delimitation in the centre, Mauritius/Maldives reasons against exercising jurisdiction over the delimitation beyond 200 nm without affirmative recommendations of the CLCS. Mauritius/Maldives reflects judicial restraint in contrast with a more proactive approach prevailing in previous jurisprudence. [ABSTRACT FROM AUTHOR]

The Antarctic benthos is rich in biodiversity, with many species being endemic to the Southern Ocean. Multiple factors such as oceanic currents, glacial cycles and reproductive life stages have been attributed to the distribution of benthic dwelling invertebrates around the continent. The sea spider (Pycnogonida) Nymphon australe is a paternal brooder, which lacks a pelagic planktonic life stage. Typically brooding is assumed to suggest limited dispersal capabilities. Here we investigated the genetic structure of N. australe, a highly abundant pycnogonid species in the Southern Ocean to test assumptions of a documented circumpolar distribution. Previous studies with mitochondrial data have revealed that N. australe has high genetic diversity, limited gene flow, as well as distinct geographic structure. To resolve the phylogeographic structure of the circumpolar N. australe from the Antarctic continental shelf, we used 3RAD single nucleotide polymorphism (SNP) data from 111 individuals sampled from ten different, circumpolar geographic regions including the Western Antarctic Peninsula, Ross Sea, Weddell Sea, and Eastern Antarctica. Analyses revealed populations to have distinct regional populations with strong geographic structuring observed by locality and suggest the possibility that N. australe may be a species complex in the Southern Ocean. [ABSTRACT FROM AUTHOR]

The solution from linear theory for the barotropic-to-baroclinic tidal energy conversion into vertical modes is validated with numerical simulations and analytical results. The main result is the translation of the traditional critical slope condition into a modewise condition on the topographic height only. Our findings are then used for estimates of the global M2 tidal conversion into the first 10 vertical modes in the open ocean (excluding the continental shelves and slopes). We observe a rapid increase with mode number of the fraction of the World Ocean where linear theory is invalid. In terms of conversion, which is highly variable in space, this corresponds to an even more rapid increase with mode number of the fraction of the converted energy that is strongly affected by nonlinear effects. Out of the 373.6 GW of the globally integrated conversion into modes 1–10, only 241.7 GW occur in locations where linear theory is valid. While it represents 95% for mode 1, this fraction rapidly drops with mode number to reach 27% for mode 10. Moreover, for the conversion into a single mode, we show that capping the linear solution at supercritical topography is inappropriate. Hence, linear theory appears unfit to directly quantify the role played by high-mode internal tides in the internal wave energy budget. [ABSTRACT FROM AUTHOR]

New biostratigraphically constrained chronologies have been developed to help elucidate the sedimentary and tectonic history of Quaternary sequences on the Hikurangi margin of north-eastern Zealandia. Three sites on the mid to lower slope of the accretionary prism (IODP Site 372-U1517, 375-U1519, 375-U1518) and two sites east of the deformation front (Hikurangi Trough Site 375-U1520 and Tūranganui Seamount Site 375-U1526) are dated using a detailed biostratigraphic framework based on planktic foraminiferal records from ODP Site 181-1123. The dating indicates sedimentation rates are very high and variable on the accretionary prism (0.2–9.6 m/kyr), especially during the Last Glacial Maximum (LGM) when downslope redeposition from the continental shelf and upper slope is common. Sedimentation rates at Hikurangi Trough Site 375-U1520 are also variable (0.01–3.0 m/kyr) and they increase markedly as the incoming site approached the deformation front, especially during the LGM, due to an abundance of downslope redeposition from the inner to mid shelf. The incoming Quaternary section at Tūranganui Seamount Site 375-U1526, is punctuated by hiatuses that shorten in duration as the site approached the deformation front, whilst sedimentation rates remain relatively low (0.04–0.4 m/kyr). [ABSTRACT FROM AUTHOR]

Submarine conduits are features responsible for transporting clastic debris from continents to the deep ocean. While the architecture of conduits has been extensively studied, the process of their inception remains unclear. This study highlights the possibility that some conduits are initiated by depositional processes involving turbidity currents. Here, we present the results of eight experiments where gravity currents were allowed to develop their own pathways. The simulation tank represented natural scales of continental shelves, slopes, and basins. The initial experiments involved sediment-laden flows with low density (1–10% in volume). In first experiment runs (Series I), sediment deposition occurred primarily on the shelf and slope, resulting in an asymmetric transverse profile. This asymmetry facilitated subsequent conservative currents (1034 to 1070 kg/m3 due to salt dissolution) flowing alongside during the second series, resulting in the formation of a constructive submarine conduit. This feature is analogous to gully formations observed in various locations. This study correlates these findings with gully-like features and proposes a model where non-confined density flows can evolve into confined flows through the construction of asymmetric topography. An evolutionary model is proposed to explain the mechanism, which potentially elucidates the formation of many submarine conduits. [ABSTRACT FROM AUTHOR]

This commentary underscores the importance of the recent discovery of the oldest in situ Holocene mangrove sediments found to date in the Caribbean region. It also emphasizes the implications of this finding for understanding postglacial sea level rise and the subsequent recolonization of current Caribbean coasts by mangrove communities. These communities likely survived the last glaciation in small microrefugia located beyond the present continental shelf, from where they expanded to form the present-day mangrove biogeographical patterns. [ABSTRACT FROM AUTHOR]

Along‐shelf wind stresses drive substantial along‐coast variations in sea level that result in significant along‐coast pressure gradients in the Middle Atlantic Bight (MAB) at time scales from days to years. Forty years of sea‐level data and reanalysis wind stresses are examined to determine the characteristics and dynamics of pressure gradients along the New England and Central MAB coasts. Along‐coast dynamic sea level (pressure) gradients often exceed 5 cm/100 km at daily time scales, 2 cm/100 km at monthly time scales and 0.2 cm/100 km at yearly time scales. Along‐shelf wind stresses account for more than 50% of the along‐coast pressure gradient variance at daily and monthly time scales and more than 25% at yearly time scales. Pressure gradients along the New England coast are primarily driven by local wind stresses along the New England shelf, while pressure gradients along the Central MAB shelf are driven by both local wind stresses along the Central MAB shelf and remote wind stresses along the New England shelf. A steady depth‐average model (Csanady, 1978, https://doi.org/10.1175/1520‐0485(1978)008<0047:tatw>2.0.co;2) accurately reproduces the wind‐driven along‐coast pressure gradients in both regions. The along‐coast pressure gradients typically oppose the local wind stress and, in the along‐shelf momentum balance, are 50%–80% of the along‐shelf wind stress over the inner shelf (water depth 15 m). Plain Language Summary: Along‐coast variations in the wind‐driven set up or set down of coastal sea level results in along‐coast pressure gradients that are an important part of the dynamics that establish currents over the continental shelf. Coastal sea level from tide gauges along the East Coast of the United States from North Carolina to Massachusetts for the 40 year period from 1982 to 2021 are used to estimate the along‐coast pressure gradients and investigate their characteristics. The established along‐coast pressure gradients tend to oppose the local wind stress and consequently reduce the strength of the resulting along‐shelf currents. However, along‐coast pressure gradients are also driven by winds to the north and east of the tide gauge because of a tendency for sea level variations to preferentially spread along the coast from the northeast toward the southwest. This component of the along‐coast pressure gradient forces along‐shelf currents caused by remote wind forcing. A simple, wind‐forced, model that includes this remote forcing accurately reproduces the observed coastal pressure gradients. Key Points: Along‐shelf wind stresses setup substantial along‐coast pressure gradients in the Middle Atlantic Bight at time scales from days to yearsThe along‐coast pressure gradients tend to oppose the wind stress and are driven by both local and remote wind stressesA steady, depth‐averaged, barotropic model proposed by Csanady (1978) accurately reproduces the observed along‐coast pressure gradients [ABSTRACT FROM AUTHOR]

Mangrove‐dominated coastlines have high carbon sequestration capacity, but it remains unclear whether tidally outwelled carbon is transformed within the coastal ocean or exported offshore. Here, we used radium isotopes (224Ra and 223Ra) to investigate carbon outwelling in two mangrove seascapes in Brazil across multiple spatial scales. We sampled porewaters to define the source composition, mangrove creek waters to resolve tidal cycles, and cross‐shelf transects to trace outwelling in coastal seascapes. Radium isotopes were positively correlated with dissolved inorganic (DIC), organic (DOC) and particulate organic (POC) carbon across the seascapes. DIC was the primary form of carbon (mean ± SD), representing 85% of the total carbon pool as bicarbonate (75 ± 11%), carbonate (6 ± 5%), and CO2 (4 ± 9%). DOC and POC accounted for 10 ± 6% and 5 ± 6% of total carbon, respectively. Although mangrove waters emitted CO2 to the atmosphere (38–143 mmol m−2 d−1), both bays and continental shelves were a CO2 sink (−2.5 to −0.5 mmol m−2 d−1) associated to chlorophyll‐a enrichments (r2 = 0.86). Total carbon outwelled from mangroves were 3–4 times higher than soil carbon burial at both mangrove sites. Bicarbonate export (27–72 mmol m−2 d−1) to the continental shelf was the major fate of carbon outwelling, more than doubling the perceived capacity of mangrove soil to sequester carbon. Hence, disregarding outwelling as a blue carbon sink mechanism would lead to underestimated assessments of how mangroves capture CO2 and help to mitigate climate change. Plain Language Summary: Mangrove forests effectively store large amounts of carbon within their muddy soils due to their complex root systems, high sedimentation rates, and high productivity. Mangroves also play a crucial role in exporting carbon to the ocean through tidal flushing and climate change mitigation. Here, we measured overlooked lateral carbon fluxes using geochemical tracers. Our findings demonstrated that mangroves could sequester 3–4 times more CO2 if total carbon exports to ocean are accounted in addition to soil carbon burial. Most of the carbon is exported as bicarbonate, with the potential to remain in seawater for millennia. We argue that a fraction of mangrove carbon is not lost during transport offshore, but rather stored in the ocean, the largest global carbon reservoir. Key Points: Porewater exchange is a pivotal component of the carbon budget within mangrove seascapesMangrove carbon outwelling oscillates between tidal cycles and reaches the continental shelf within 1–3 weeksCarbon sequestration via outwelling to the ocean was 3–4 times greater than soil burial [ABSTRACT FROM AUTHOR]

An investigation was done to determine the texture, organic matter content, and geochemical characteristics of sediments collected from the continental shelf of the South Western Bay of Bengal. The present study portrays the abundance of sand followed by slightly muddy sand, muddy sand, sandy mud, sandy, and slightly sandy mud in the study area. The mean size of the sediment ranges from 0.40 to 3.57 mm (coarse sand to very fine sand). The sediments are very well to very poorly sorted, coarsely skewed to fine skewed, and platykurtic to very leptokurtic in nature. Trace metals, such as Cu, Co, Fe, Mn, Pb, Zn, Cr, and Ni were analyzed. A relatively high percentage of organic matter is attributed to the predominance of finer sediments entering through the minor and major rivers. The higher trace metal concentration in the study area is closely associated with mud content and Fe is the most abundant trace metal in the study area. Formation of Fe- and Mn-hydroxides in the near-shore regions is responsible for scavenging Pb, Zn, Cu, Ni, and Cr and effectively incorporating them into the inner shelf sediments. Among all the trace metals, the concentration of Co, Pb, Cr, and Ni is found to be higher than the average crustal abundance value marking the role of anthropogenic sources predominantly from industrial, agricultural, scrap metal recycling, sewage, and tourism activities. [ABSTRACT FROM AUTHOR]

Rhodolith beds are one of the major marine coastal ecosystems. Knowing the spatial distribution, environmental characteristics and composition is not only scientifically pertinent but also crucial to allow comparisons in case of changes due to local and global anthropogenic pressures. With slow algal growth rates, high associated diversity and potential importance as nursery grounds, rhodolith beds are present along the Brazilian coast of the Southwest Atlantic Ocean. This study provides an updated map of shallow and mesophotic rhodolith distribution after a systematic literature review. The prevailing oceanographic conditions along most parts of the Brazilian coast render the environment suitable for the developing rhodolith beds (a total of 68 taxa in this review), with 63 taxa along the East Brazilian Shelf, seven taxa for the North Brazilian Shelf and 10 taxa in the South Brazilian Shelf. According to composition, shallow and mesophotic communities were more similar in each large marine ecosystem than among them. In addition to gaps in terms of distribution, there are uncertainties about the taxonomic composition of the rhodoliths, associated fauna and flora and oceanographic and geological characteristics of the bottoms, which call attention to the importance of further studies, mainly in the mesophotic. This review provides a more precise distribution of these habitats along the Brazilian coast of the Southwest Atlantic Ocean. It contributes to a more detailed taxonomic composition of calcareous algae in an extremely relevant marine ecosystem, which is crucial for many species, including the endemic kelp, Laminaria abyssalis. [ABSTRACT FROM AUTHOR]

The present study aims to detect early changes in the community structures of macrozoobenthos and indications of their recovery following sand excavation activities in the soft bottom of the southern continental shelf area, Korea strait, from August 2002 to October 2005. About 10 million m3 of relict sandy sediments were excavated from a 9 km2 area over 18 months, from June 2002 to April 2004. The sand excavation and collection activities in the study area increased the sand amount in the residual sediments due to the complete loss of fine surface sediments. However, the fine particles in the turbidity flumes produced by sand hopper vessels were deposited in neighboring zones. The overall ecological impacts of the sand excavation activity are the rapid loss of macrobenthic animals in the central region of the excavation area and the decrease in densities of some disturbance-sensitive macrobenthos, such as Ampelisca spp. and Photis longicaudata that are dominant in the marginal parts of the excavation area. The burrowing polychaete Ophelina acuminata and the opportunistic tube-building polychaete Paraprionospio coora were the most predominant species in the central region of the study area following 12 months. The affected regions showed decreases in the abundance and recovery of the macrozoobenthic fauna species depending on the changes in sediment properties induced by the sand excavation activities, such as sediment loss and material deposition materials. One and a half years after the cessation of the sand excavation activities, the density of the most abundant species was increased and comparable to those in the reference area. In addition, the biological characteristics of the macrobenthic community showed indications of recovery to their previous status, with different faunal compositions and densities. Further long-term ecological monitoring of the macrobenthic communities is necessary to comprehensively assess their recovery processes following sand excavation in the study area. [ABSTRACT FROM AUTHOR]

The first systematic sediment survey by the icebreaker Shirase (AGB-5003) was conducted during the 61st Japanese Antarctic Research Expedition (JARE-61). Sediment samples were obtained from a total of 28 sites in 3 areas of the Totten Glacier front–Dalton polynya, Lützow-Holm Bay and Cape Darnley polynya using a large-bore gravity corer and GSJ-type K-grab sampler. In this paper, details of the survey operation are described as a reference for the future experience. In addition, preliminary results of the obtained sediments are reported as a fundamental information for future analysis using these samples.

The study of emergency or crisis management practices acquires strategical relevance for resilient decision‐making under uncertainty. The assessment of system resilience is an asset to identify potential design or operational improvements of a complex socio‐technical system, such as an Emergency Management (EM) system. This research aims at analyzing the functional properties of an EM system recurring to a novel integration of the Functional Resonance Analysis Method (FRAM) and Bayesian Belief Networks (BBN). The FRAM is used to model and display the actors and the interactions in the system, while the BBN, dynamically updated when new data becomes available, supports a complementary quantitative assessment. The methodology is iterated in the analysis of an EM procedure, issued by a second‐line Emergency Response organization for Oil and Gas (O&G) operators in Norwegian continental shelf. The results of the study show that the proposed stochastic methodology compensates the drawbacks of traditional FRAM modeling, via the outcomes of BBN quantitative analyses. The findings, contextualized in EM, can be transferred to different socio‐technical contexts, both military and civil ones. [ABSTRACT FROM AUTHOR]

Across the world's oceans, our knowledge of the habitats on the seabed is limited. Increasingly, video/imagery data from remotely operated underwater vehicles (ROVs) and towed and drop cameras, deployed from vessels, are providing critical new information to map unexplored benthic (seabed) habitats. However, these vessel-based surveys involve considerable time and personnel, are costly, require favorable weather conditions, and are difficult to conduct in remote, offshore, and deep marine habitats, which makes mapping and surveying large areas of the benthos challenging. In this study, we present a novel and efficient method for mapping diverse benthic habitats on the continental shelf, using animal-borne video and movement data from a benthic predator, the Australian sea lion (Neophoca cinerea). Six benthic habitats (between 5-110m depth) were identified from data collected by eight Australian sea lions from two colonies in South Australia. These habitats were macroalgae reef, macroalgae meadow, bare sand, sponge/sand, invertebrate reef and invertebrate boulder habitats. Percent cover of benthic habitats differed on the foraging paths of sea lions from both colonies. The distributions of these benthic habitats were combined with oceanographic data to build Random Forest models for predicting benthic habitats on the continental shelf. Random forest models performed well (validated models had a >98% accuracy), predicting large areas of macroalgae reef, bare sand, sponge/sand and invertebrate reef habitats on the continental shelf in southern Australia. Modelling of benthic habitats from animal-borne video data provides an effective approach for mapping extensive areas of the continental shelf. These data provide valuable new information on the seabed and complement traditional methods of mapping and surveying benthic habitats. Better understanding and preserving these habitats is crucial, amid increasing human impacts on benthic environments around the world. [ABSTRACT FROM AUTHOR]

The recent judgments of the International Court of Justice (ICJ) in Nicaragua v. Colombia and of a special chamber of the International Tribunal for the Law of the Sea in Mauritius/Maldives provide significant developments to the legal regime of the continental shelf within the law of the sea, as well as its relationship to the exclusive economic zone. Specifically, the ICJ stated that the continental shelf beyond 200 nautical miles cannot overlap with the area within 200 nautical miles of another State’s baselines. This decision potentially creates a new constraint line to a coastal State’s entitlement to a continental shelf beyond 200 nautical miles. Furthermore, the two decisions blur the distinction between delineation and delimitation of the continental shelf. They hold significant implications for the concept of a ‘single continental shelf’ and raise questions about the necessity of establishing grey areas in the future. [ABSTRACT FROM AUTHOR]

Weakfish (Cynoscion regalis) is not federally managed but feeds on species of management and ecological interest. We examined the trophic ecology of weakfish in Chesapeake Bay and the coastal and offshore waters of the eastern United States. For these areas, we determined the dominant prey of weakfish; identified how much diet variation was explained by the factors: season, size class, and year; and quantified prey biomass removed by weakfish from 2007 to 2019. In general, diet composition was mostly dominated by Engraulidae, Osteichthyes (bony fishes), and Mysidacea, and significantly varied by season and size class in Chesapeake Bay and coastal waters, although this was less dramatic in Chesapeake Bay. The total amount of variance explained by the three factors was 23.1% (Chesapeake Bay) and 14.7% (coastal waters), with year not being a significant factor in explaining weakfish diet variation for these areas. Weakfish total prey biomass removal occurred primarily in coastal waters in the fall and small size class (annual mean: approximately 41,038 t; maximum: approximately 63,793 t). Highly opportunistic feeders, weakfish cannibalism also played an essential part of their diet. These results have implications for fisheries and ecosystem management of weakfish when considering ecological interactions in regulatory approaches, such as recruitment and cannibalism, competition with federally managed fishes, and the natural mortality of their prey. [ABSTRACT FROM AUTHOR]

The southeastern Australian margin hosts a series of submarine canyons. Although the origin and evolution of canyons within the northwestern segment of the margin is relatively well studied, their quantitative morphology, interaction with longshore drift currents and slope failure remain poorly understood in the southeastern region. In this study, high-resolution bathymetry and 3D seismic reflection datasets revealed five main submarine canyons present in the central offshore Otway Basin. The canyons have V-shaped, evolving to U-shaped morphology downslope with sedimentary infill characterized by medium–high amplitudes, recognizable stratal pattern and localized chaotic seismic reflections. Analysis reveals these canyons were initiated by retrogressive slope failure on the continental slope, that once the shelf edge was reached and subsequently incised, development of the canyon heads was influenced by the shelf parallel Zeehan Current, active on the continental shelf of the region. The heads of the shelf-incised canyons preferentially migrate northwestward and were infilled by laterally accreting sedimentary packages characterized by southeast dipping seismic reflections. These indicate an early erosive phase followed by a period of deposition, a result of the prevalent eastward flowing Zeehan Current. These results have important implications for understanding of the mechanisms that control initiation and development of submarine canyons, and their morphology, both offshore southeastern Australia, and similar settings on continental margins worldwide. [ABSTRACT FROM AUTHOR]

The ocean has absorbed anthropogenic carbon dioxide (Canthro) from the atmosphere and played an important role in mitigating global warming. However, how much Canthro is accumulated in coastal oceans and where it comes from have rarely been addressed with observational data. Here, we use a high-quality carbonate dataset (1996-2018) in the U.S. East Coast to address these questions. Our work shows that the offshore slope waters have the highest Canthro accumulation changes (ΔCanthro) consistent with water mass age and properties. From offshore to nearshore, ΔCanthro decreases with salinity to near zero in the subsurface, indicating no net increase in the export of Canthro from estuaries and wetlands. Excesses over the conservative mixing baseline also reveal an uptake of Canthro from the atmosphere within the shelf. Our analysis suggests that the continental shelf exports most of its absorbed Canthro from the atmosphere to the open ocean and acts as an essential pathway for global ocean Canthro storage and acidification. [ABSTRACT FROM AUTHOR]

Continental shelves experience many human pressures with demersal fisheries central to disturbing the ocean floor. However, ecological processes such as predation rates of benthos and their relationship with bottom fishing are often unknown for large marine ecosystems. We examined the amount of benthos consumed by 14 benthivorous fishes, the overlap between benthos predation and bottom fishing (dredge and trawl gear), and temporal trends in benthivorous fish abundance and the number of fishing trips on the northeast US continental shelf. Mean annual predation (biomass of prey removed) and 95% confidence intervals ranged from .0002 (.0001–.0003) to 3967 (1761–7112) t per 10‐min area squared grid cell and prey taxa for these benthivorous fishes. Predation and bottom fishing had overlapping footprints of activity, which were slightly stronger for dredge gear. Trophic success (ratio of prey biomass eaten to the biomass of the benthivore community per grid cell) revealed more Bivalvia, Gammaridea, and Polychaeta eaten in areas targeted by trawling with more fish biomass. In contrast, dredging did not target fish biomass, but these areas had increased (Echinoidea, Gammaridea, and other benthos) or decreased (Ophiuroidea) trophic success relative to dredging footprint, suggesting habitat preferences for benthic prey and demersal fisheries have converged rather than diverged. Despite declines in bottom fishing, recent increases in benthivorous fish abundance and growing interest in ocean floor use suggest that fisheries managers should ensure benthivores have sufficient prey resources relative to their community size and human pressures to promote long‐term sustainability of demersal fisheries and healthy ecosystems. [ABSTRACT FROM AUTHOR]

A study on Holocene ostracods (subfamilies Cytherurinae and Paracytherideinae) was carried out in 500 bottom sediments samples recovered along the Brazilian continental shelf from Rio Grande do Sul (33º45’S/52ºW) to Espírito Santo (19º35’S/40ºW) states. New species belonging to the subfamily Cytherurinae are here identifi ed and described as follows: Eucytherura rara sp. nov., E. trifi da sp. nov., E. castellata sp. nov., and Semicytherura reticulocostata sp. nov. Three other species are kept in open nomenclature due to scarcity of material for study: Semicytherura sp. 1, Semicytherura sp. 2 and Hemingwayella sp., the last one representing the subfamily Paracytherideinae. The zoogeographical and stratigraphical analyses revealed that most of the species identifi ed do not exceed the latitude 19º30.1’S with the southernmost record at 33º52’S; some of these species extending to the Uruguayan and Argentinian shelves. Exceptions are the species Semicytherura parallelocostata and Semicytherura sp. 2 that reach the northeast and equatorial Brazilian continental shelves at latitudes 10º32’S and 00º08’S, respectively. Two of the studied species have a fossil record in the Pelotas Basin (Brazil): Hemicytherura auriculata (Miocene and Pleistocene) and Semicytherura rugosoreticulata (Holocene). Hemicytherura lapillata has been recorded in a Holocene outcrop in Bahia Blanca (Argentina). [ABSTRACT FROM AUTHOR]

Sablefish (Anoplopoma fimbria, Anoplopomatidae) and shortraker rockfish (Sebastes borealis, Sebastidae) co-occur in deepwater marine habitats in the northeast Pacific. Both species are economically valuable, but their ecologies are not well known. We used stable isotope analysis of carbon and nitrogen to explore isotopic niches of A. fimbria and S. borealis in two distinct locations—a deep strait in the inside passage area and an open coastal area of the continental shelf, both in southeast Alaska, USA. Anoplopoma fimbria and S. borealis exhibited similar positions of isotopic niches based on nitrogen and carbon isotopic ratios, suggesting potential interspecific competition, especially in the inside location. In addition, S. borealis had a smaller niche breadth compared to A. fimbria in the coastal location. Both species had enriched nitrogen and carbon isotopic ratios in the inside location compared to the coastal location. Differences in isotopic niches between these two locations suggest the possibility of location-specific variation in isotopic niches of these two species of widespread, abundant deepwater fishes. [ABSTRACT FROM AUTHOR]

Estuaries are one of the most productive ecosystems in the world, supporting a variety of flora and fauna. Primary productivity by phytoplankton is a rich source of organic carbon, substantial for the aquatic food web. Monitoring phytoplankton (i.e., chlorophyll-a) is essential to assess the health of estuaries and other continental shelves subjected to constant anthropogenic stress (e.g., developmental activities). In this study, a three-endmember combination Spectral Decomposition Algorithm (SDA) was developed to estimate the phytoplankton in the micro-tidal Yura estuary of Japan using Landsat-8 (30 m), and Sentinel − 2A (10 m). The endmember water, phytoplankton, and submerged aquatic vegetation (SAV) yielded the best results with both the satellite sensors (R2 > 0.80) owing to the limited influence of non-phytoplankton suspended solids (NPSS) in the estuary. Chlorophyll-a was used as the proxy for phytoplankton. The estimated root mean square error (RMSE) was relatively higher in Landsat-8 (RMSE = 0.187 µg/L) than the Sentinel-2A (RMSE = 0.162 µg/L). The results were validated using the ground truth data of the Yura Estuary (26 sampling points). Furthermore, the results indicate low chlorophyll-a concentration in the Yura estuary (< 2µg/L) except near the shorelines (~ 6 µg/L). A good fit (R2 = 0.79) between observed chlorophyll-a and turbidity indicated phytoplankton-dominated turbidity in the tide-less estuary of Japan. The estimated maximum turbidity was 1.4 FTU using both sensors, suggesting a low anthropogenic influence on the Yura Estuary. The study demonstrates a successful application of the spectral decomposition algorithm (SDA) in the coastal waters which could further be used to assess the horizontal and temporal variability in phytoplankton in estuarine water. [ABSTRACT FROM AUTHOR]