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Morphological alterations of the gill and digestive gland were studied in Magallana gigas from areas with different degrees of human activity over one year. For that, the height of the plicas and filaments of the gill and the mean epithelial thickness were measured, the ratio of cell type and tissue composition analyzed of the digestive gland as well as alterations in the pattern of structural organization in these organs were assessed. The specimens were collected in November 2021, and February, May and August 2022 from two representative sampling sites of distinct anthropic pressures in the coastal area of Buenos Aires Province: Arroyo Parejas (AP, 38° 55′ S, 62° 04′ W) and Pehuén-Có (PC, 39° 01′ S; 61° 32' W). The results of the morphological parameters, ratio of cell-type, tissue composition, and histological alterations of M. gigas showed differences between the studied areas and seasons, suggesting a negative relationship between human activity and the health of the gills and digestive gland of the oyster. Understanding the gill and digestive gland morphology of oysters, as well as their response to varying levels of human activity in the study region, could help mitigate the impacts of this non-native species. [ABSTRACT FROM AUTHOR]

This study introduces new insights into the climatology of South Atlantic (SAt) cyclones by employing a novel cyclone life cycle detection method, the CycloPhaser. Utilizing the minimum relative vorticity series and its derivative at the cyclone centre, the program effectively identifies distinct phases in the cyclone life cycle. Cyclone tracks are obtained through the analysis of relative vorticity at 850 hPa, using the ERA5 dataset. The study identified six main cyclone life cycle patterns from the analysis of 28,458 systems. The predominant cyclone type, accounting for approximately 60% of the analysed systems, exhibited a four‐phase configuration: incipient, intensification, mature and decay. Detailed statistics for each developmental phase and the overall life cycle are presented, offering valuable comparisons and new insights while corroborating previous research findings. Key genesis regions in the SAt are identified, along with track density maps that reveal distinct preferences in cyclone developmental cycle. The main outcome of this study is the demonstration that the automated classification procedure enables the analysis of cyclones' life cycles to be conducted promptly and with low computing costs, facilitating the comprehensive study of cyclone behaviour with high efficiency. [ABSTRACT FROM AUTHOR]

Coral‐based stable oxygen isotopes (δ18O) have been used as a proxy for sea surface temperature (SST) since the 1970s, and δ18O–SST calibration studies have been fundamental to assure robust and faithful SST reconstructions. Paleoclimatic studies based on corals from the tropical western South Atlantic (TWSA) are scarce, and the available coral species need to be calibrated to improve climate and environmental reconstructions. Siderastrea stellata, a slow‐growing coral, is a potential species to be explored as a coral archive in the TWSA. We provide the first multi‐site δ18O–SST calibration for the coral S. stellata from three locations at the TWSA: Todos os Santos Bay, Tamandaré and the Rocas Atoll. Pseudo‐coral δ18O calculations derived from gridded SSS and SST show that the contributions of SSS and SST to coral δ18O are expected to be different at each site. Weighted least squares linear regressions performed between the δ18O and SST generated the following calibrations equations: δ18O = −0.18 (±0.02) × SST (°C) + 1.90 (±0.47) for Todos os Santos Bay; δ18O = −0.18 (±0.02) × SST (°C) + 1.54 (±0.67) for Tamandaré; and δ18O = −0.16 (±0.03) × SST (°C) + 1.24 (±0.71) for the Rocas Atoll. The δ18O‐SST sensitivity of S. stellata from the TWSA is similar to that of other slow‐growing species of the genus and consistent with the expected δ18O‐SST sensitivity of other species reported in the literature. These calibrations will allow future SST reconstructions based on δ18O records from sub‐fossil and fossil S. stellata, an abundant species in the TWSA. Plain Language Summary: Corals continuously biomineralize calcium carbonate, storing environmental information within their exoskeletons in geochemical and isotopic records that span hundreds of years and making them suitable for high‐resolution climate reconstructions. The stable oxygen isotopes (δ18O) found in corals are an important proxy for revealing past sea surface temperatures (SST) and sea surface salinities (SSS). However, to ensure that this proxy is applicable to reconstruct past SST, further δ18O–SST calibration studies are needed on various regions and species. In this study, we carried out three field work experiments to provide the first multi‐site δ18O–SST calibration of the slow‐growing coral Siderastrea stellata from the western South Atlantic. Despite the slow growth nature of S. stellata corals that poses a challenge to high temporal resolution sampling, we successfully provided new calibration equations for SST reconstruction from three different locations in the western South Atlantic. Our calibration equations can now be applied to reconstruct SST based on coral δ18O records from sub‐fossil and fossil coral cores. Key Points: First multi‐site δ18O‐SST calibrations for the slow‐growing coral Siderastrea stellata from the western South Atlanticδ18O–SST sensitivity for S. stellata varied from −0.15 to −0.19‰ per °C across the different reef environmentsThis study paves the way for using S. stellata δ18O from fossil and subfossil corals for paleoclimate reconstructions from the western South Atlantic [ABSTRACT FROM AUTHOR]

The Colatina Fracture Zone (CFZ) defines a distinct NNW–SSE‐oriented linear zone of fractures and brittle faults that represents an inherited weak zone in the current crustal structure of the (Pre)Cambrian Araçuaí Orogen. In the Early Cretaceous, the CFZ was reactivated during rifting of West Gondwana and subsequent opening of the South Atlantic Ocean, as evidenced by the emplacement of dykes along its structural network and the development of major depocentres of the Campos Basin in the offshore segments of the CFZ. Previous thermochronological studies have demonstrated that the CFZ was also rejuvenated during the drift phase of the South Atlantic. However, a number of questions regarding differential surface uplift and basement exhumation between the CFZ and its surrounding areas, such as the Doce River Valley (DRV), are still unresolved. In this study, we aim to investigate the CFZ as a distinctive structure in the tectonic rejuvenation of the passive margin of south‐east Brazil. Samples from the CFZ and the DRV were collected for apatite fission‐track (AFT) analyses. In the DRV, samples yield AFT central ages from 87 to 97 Ma with mean track lengths (MTL) from 12.6 to 13.3 μm. In contrast, in the CFZ, AFT central ages from 70 to 83 Ma with MTL values from 13.2 and 13.4 μm are obtained. The correlation between AFT age and elevation suggests that the tectonic development of these regions was markedly different and uncoupled. The thermal history models from the AFT data further constrain this differential evolution. On the one hand, thermal history modelling for the DRV indicates a slower and protracted cooling since the incipient Atlantic rifting in the Early Cretaceous. On the other hand, the models for CFZ reveal a rapid cooling phase between the Late Cretaceous to the Palaeocene. In the DRV, the observed basement cooling was most probably triggered by erosion of the uplifted rift shoulder generated by Gondwana break‐up. The more recent, Late Cretaceous–Palaeocene rock cooling, localized in the CFZ, was synchronous with a major phase of the Andean orogeny. This suggests that reactivations and erosional exhumation of the CFZ basement could be a consequence of far‐field propagation of intraplate compressional stress. The higher susceptibility of the CFZ to reactivating over its surroundings shows that structural inheritance is a key factor in the differential tectonic evolution of passive margins. Further research on the Late Cretaceous–Palaeocene reactivation in the CFZ's offshore extension may be crucial for the exploitation of hydrocarbons in the Campos and Espírito Santos basins. [ABSTRACT FROM AUTHOR]

During the Early Cretaceous, massive evaporite accumulations formed in the opening South Atlantic. However, the depositional model of these salts is still poorly constrained at the scale of the West African margin. The present study focuses along the proximal domain of the south Gabon‐Congo‐Cabinda margin and is based on (i) log interpretations of 246 wells crossing undeformed to weakly deformed evaporite intervals and (ii) a structural characterization of the basement. The evaporites show 11 regional evaporite depositional cycles (CI–CXI) bounded by meter‐thick shale beds. The cycles display alternating meter‐scale carnallite‐halite beds that can be correlated over several hundred kilometres, and CVI, CVII, CVIIIa and CX culminate in localized tachyhydrite accumulations. Cross section correlations and isopach maps help to understand the palaeogeographical evolution of each cycle and depositional environments that evolved from relatively deep at the base of cycles, to very shallow at their top. CI formed a mosaic of halite‐prone depocenters deposited in pre‐salt topographic relief. CII and CIII were deposited uniformly over a flattened basin in a highly extended brine pond. From CIV to CVIIIa, the stratigraphic architecture of the salts was shaped by freshwater inflow sourced from the north and possible basement movements. This setting, together with an increased confinement of the proximal domain from the distal one with basin drawdown, favoured the development of depocenters with perennial subaqueous conditions and extreme salinities, in which more than 70 m of tachyhydrite accumulation could locally be preserved. From CVIIIb to CXI, the basin returned to a flat depositional setting without well‐developed depocenters and with increasing subsidence westwards. Marine influx increased starting from CX, allowing the deposition of sulphate beds. The salt section is capped by anhydrite deposits interbedded with clastic and dolomite, before the final marine invasion of the basin. For the first time, this study provides a large‐scale depositional tectonostratigraphic setting of the Aptian salts in the proximal domain of the West African margin. The results are of interest for K‐Mg salts exploration resources in the Aptian and pave the way for further investigation of the salt depositional environment in the distal domain of the margin. [ABSTRACT FROM AUTHOR]

The sub-Antarctic island of South Georgia is surrounded by highly productive waters, supporting dense aggregations of Antarctic krill (Euphausia superba), a vital food source for globally important seabird and marine mammal populations. These waters also support a commercial fishery for Antarctic krill. Regular monitoring of key krill predator species is undertaken at South Georgia to detect any changes in the ecosystem in response to harvesting activities. This monitoring provides essential data but is focused on land-breeding animals during the austral summer, whilst the krill fishery operates exclusively in winter. Here, we report the results of at-sea surveys to investigate abundance and distribution of krill-dependent predators from winter 2010 and 2011, which represented a "poor" krill year and "good" krill year, respectively. Correspondingly in 2011 higher numbers of krill predators were observed; notably Antarctic fur seals (Arctocephalus gazella) across the northern shelf. Spatial overlap between fur seals and the krill fishery occurred mainly within the krill fishery hotspot to the north-east, highlighting the potential for locally high levels of competition. Cetaceans were observed during both survey years, but in low numbers compared to recent studies. Gentoo penguins (Pygoscelis papua) were the most frequently observed penguin species, showing an inshore distribution and almost no overlap with the krill fishery. Diving-petrels (Pelecanoides spp.) were the most abundant flying seabirds, observed across all transects, with particularly high densities to the south in early winter 2010. In conclusion, this survey provides valuable baseline data on the distribution of South Georgia's predators during the winter months. [ABSTRACT FROM AUTHOR]

[Display omitted] • The landscape evolution in the alkaline-carbonatite complexes were studied. • The Araxá and Catalão I complexes were simultaneously emplaced at ∼85 Ma. • Fast exhumation occurred between 85 and 65 Ma at Araxá and 85–45 Ma at Catalão I. • Once exhumed, the denudation rates were 3.4 m Ma −1 at Araxá and 4.7 m Ma −1 at Catalão I. • Geological and climate factors control the Cenozoic landscape evolution at the APIP. The timing and rate of emplacement, exhumation, and weathering of alkaline-carbonatite complexes associated with failed rift systems in the South Atlantic provide constraints on the thermotectonic conditions of West Gondwana before, during, and after break-up. 40Ar/39Ar geochronology of biotite crystals show that two alkaline-carbonatite complexes – Araxá and Catalão I – from the Alto Paranaíba Igneous Province were shallowly emplaced simultaneously at ∼85 Ma. After rapid cooling, the igneous complexes were rapidly exhumed between 85 and 66 Ma at Araxá (∼52 m Ma −1) and 85 and 45 Ma at Catalão (∼25 m Ma −1). Fast exhumation of the complexes occurred under relatively arid to semi-arid climates, conditions that favored physical weathering and erosion. The eroded material was transported in a NE-SW direction and deposited in the adjacent Paraná and São Sanfranciscana basins. After exhumation, wetter climates and more subdued tectonic conditions favored active widespread vegetation cover that favored reduced erosion and deepening of weathering profiles. After 66 Ma, the Araxá complex denuded at rates of 3.4 m Ma −1; at Catalão I, denudation rates reduced to 4.7 m Ma −1 after ∼45 Ma. Favorable geological and climatic conditions promoted the formation of deep and chemically stratified lateritic weathering profiles. The exhumed and weathered carbonatites underwent hypogene and supergene enrichment in Nb, P, Ti, and REEs, critical metals needed for the electrification of our energy base. The preservation of the lateritic profiles and their mineral wealth in the continental interior contrasts with the younger and shallower weathering profiles formed on similar lithologies and at equivalent elevations near the Brazilain South Atlantic margin, confirming that climatic and tectonic conditions along the margin were less conducive to the preservation of valuable mineralized systems because of enhaced erosion. [ABSTRACT FROM AUTHOR]

Monthly climatology data for salinity fronts in the South Atlantic have been created from satellite SMOS sea surface salinity (SSS) measurements taken from 2011–2019, processed at the Barcelona Expert Center of Remote Sensing (BEC), and provided as high-resolution (1/20°) daily SSS data. The SSS fronts have been identified with narrow zones of enhanced horizontal gradient magnitude (GM) of SSS, computed using the Belkin–O'Reilly algorithm (BOA). The SSS gradient fields generated by the BOA have been log-transformed to facilitate feature recognition. The log-transformation of SSS gradients markedly improved the visual contrast of gradient maps, which in turn allowed new features to be revealed and previously known features to be documented with a monthly temporal resolution and a mesoscale (~100 km) spatial resolution. Monthly climatologies were generated and analyzed for large-scale open-ocean SSS fronts and for low-salinity regions maintained by the Rio de la Plata discharge, Magellan Strait outflow, Congo River discharge, and Benguela Upwelling. A 2000 km-long triangular area between Africa and Brazil was found to be filled with regular quasi-meridional mesoscale striations that form a giant ripple field with a 100 km wave length. South of the Tropical Front, within the subtropical high-salinity pool, a trans-ocean quasi-zonal narrow linear belt of meridional SSS maximum (Smax) was documented. The meridional Smax belt shifts north–south seasonally while retaining its well-defined linear morphology, which is suggestive of a yet unidentified mechanism that maintains this feature. The Subtropical Frontal Zone (STFZ) consists of two tenuously connected fronts, western and eastern. The Brazil Current Front (BCF) extends SE between 40 and 45°S to join the subantarctic front (SAF). The STFZ trends NW–SE across the South Atlantic, seemingly merging with the SAF/BCF south of Africa to form a single front between 40 and 45°S. In the SW Atlantic, the Rio de la Plata plume migrates seasonally, expanding northward in winter (June–July) from 39°S into the South Brazilian Bight, up to Cabo Frio (23°S) and beyond. The inner Plata front moves in and out seasonally. Farther south, the Magellan Strait outflow expands northward in winter (June–July) from 53°S up to 39–40°S to nearly join the Plata outflow. In the SE Atlantic, the Congo River plume spreads radially from the river mouth, with the spreading direction varying seasonally. The plume is often bordered from the south by a quasi-zonal front along 6°S. The diluted Congo River water spreads southward seasonally down to the Angola–Benguela Front at 16°S. The Benguela Upwelling is delineated by a meridional front, which extends north alongshore up to 20°S, where the low-salinity Benguela Upwelling water forms a salinity front, which is separate from the thermal Angola–Benguela Front at 16°S. The high-salinity tropical water ("Angola water") forms a wedge between the low-salinity waters of the Congo River outflow and Benguela Upwelling. This high-salinity wedge is bordered by salinity fronts that migrate north–south seasonally. [ABSTRACT FROM AUTHOR]

Three new eyeless species of Nereis from organic falls (whale bones and wood parcels) in the Southwestern Atlantic from depths between 550 and 3285 m are described, and the eyeless species Neanthes shinkai is transferred to Nereis. All new species and Nereis shinkai comb. nov. can be distinguished from the majority of Nereis species by the absence of eyes and by the presence of small and delicate paragnaths. Interestingly, the species Nereis anoculepitoka sp. nov. presents epitoky, with sexual dimorphism and the morphological variations described herein. This is the first description of an eyeless epitoke form from organic falls in the deep ocean. We conducted molecular phylogenetic analyses using COI and 16S mitochondrial genes, confirmed the morphological identification and established an eyeless clade within Nereis including the three new species and Nereis shinkai comb. nov. The presence of different species in a relatively small geographical area can be explained, in part, by the action of different water masses in each sampling site and suggests that organic islands are potential hotspots for specialization of Nereis in the deep sea. [ABSTRACT FROM AUTHOR]

New species of the genera Spirobolbolaimus and Ixonema (Nematoda: Microlaimidae) have been found in sediment samples collected in the South Atlantic, along the Continental Shelf break off Northeastern Brazil. Different to other Spirobolbolaimus species, S. pernambucanus sp. nov. possesses six outer labial setae and four cephalic setae with approximately the same length. Ixonema gracieleae sp. nov. differs from other species of Ixonema in having somatic setae on peduncles. This is the first time that new species of these taxa have been described for the Brazilian coast. An amendment of the diagnosis and a dichotomous key are proposed for both genera.

Abstract Coral‐based stable oxygen isotopes (δ18O) have been used as a proxy for sea surface temperature (SST) since the 1970s, and δ18O–SST calibration studies have been fundamental to assure robust and faithful SST reconstructions. Paleoclimatic studies based on corals from the tropical western South Atlantic (TWSA) are scarce, and the available coral species need to be calibrated to improve climate and environmental reconstructions. Siderastrea stellata, a slow‐growing coral, is a potential species to be explored as a coral archive in the TWSA. We provide the first multi‐site δ18O–SST calibration for the coral S. stellata from three locations at the TWSA: Todos os Santos Bay, Tamandaré and the Rocas Atoll. Pseudo‐coral δ18O calculations derived from gridded SSS and SST show that the contributions of SSS and SST to coral δ18O are expected to be different at each site. Weighted least squares linear regressions performed between the δ18O and SST generated the following calibrations equations: δ18O = −0.18 (±0.02) × SST (°C) + 1.90 (±0.47) for Todos os Santos Bay; δ18O = −0.18 (±0.02) × SST (°C) + 1.54 (±0.67) for Tamandaré; and δ18O = −0.16 (±0.03) × SST (°C) + 1.24 (±0.71) for the Rocas Atoll. The δ18O‐SST sensitivity of S. stellata from the TWSA is similar to that of other slow‐growing species of the genus and consistent with the expected δ18O‐SST sensitivity of other species reported in the literature. These calibrations will allow future SST reconstructions based on δ18O records from sub‐fossil and fossil S. stellata, an abundant species in the TWSA.

Scalibregmatidae Malmgren, 1867 is a family of annelids, with only few taxa reported from Brazil. In this work, we describe two new species of Asclerocheilus Ashworth, 1901. The new species A. geiseae sp. nov. and A. blakei sp. nov. were collected during scientific expeditions to the Espírito Santo and Campos sedementary basins. These expeditions were coordinated by PETROBRAS/CENPES. The species A. geiseae sp. nov. is unique among its congeners by the presence of acicular spines with rounded and curved tips in two rows. The second species, A. blakei sp. nov., differs from its congeners by the combination of the presence of a trapezoidal prostomium, acicular spines on chaetigers 1–3, lyrate chaetae from chaetiger 3 on notopodia and 2 on neuropodia. Moreover, we report the species A. tropicus Blake, 1981 from the localities sampled on this study. We also provide an identification key to all species of Asclerocheilus of the world.

Pseudoscorpiones are compose an ancient order of arachnids, occur in a wide variety of terrestrial habitats worldwide, with representatives of various genera occurring exclusively in insular habitats. The primary objective of this study was to determine the composition and distribution of Pseudoscorpiones within the Brazilian equatorial oceanic islands. To determine Pseudoscorpiones communities and distribution in coastal environmental habitats of the Brazilian equatorial oceanic islands (Fernando de Noronha archipelago, Rocas Atoll and St. Peter and St. Paul rocks), was defined three zones along the insular environmental gradient in the Brazilian equatorial oceanic islands. These zones include the Sand Beach (SB) closest to the intertidal zone, the Slope Forest (SF) with a sloping terrain and the Top Forest (TF) farthest from the beach. Collecting points were distributed in each zones (SB, SF, and TF) at distances greater than 1 km, with four samples collected at each point approximately 12.5 m apart from each other. The TF zone is observed only in Fernando de Noronha. In our study we found pseudoscorpions exclusively on the islands of the Fernando de Noronha archipelago. We collected 5 species from the Hesperolpiidae and Syarinidae families. The SF habitats exhibited greater species richness, while the Upper Forest habitats showed greater population abundance. Notably, we recorded pseudoscorpions (Ideoblothrus amazonicus) in bird nests (Sula dactylatra) on Rata Island, suggesting the use of nests as habitat, reproduction, and, possibly, occasional transport to and from other habitats. No pseudoscorpions were found in SB environments. Landscape changes and tourism can threaten this incredible newly discovered community, vital for monitoring environmental changes in this delicate ecosystem.

Three new species of the Microlaimus genus (Nematoda: Microlaimidae) are described from sample sediments collected in the South Atlantic, along the Continental Shelf break of Northeastern Brazil. Microlaimus paraundulatus sp. n. possesses four setiform cephalic sensillae, a buccal cavity with three small teeth, arched and slender spicules and a wave-shaped gubernaculum. Microlaimus modestus sp. n. is characterized by four small cephalic sensillae, a buccal cavity with three teeth (one large dorsal tooth), cephalated spicules and a strongly arched gubernaculum in the distal region. Microlaimus nordestinus sp. n. is characterized by the following set of features: relatively long body, eight rows of hypodermal glands that extend longitudinally along the body and a funnel-shaped gubernaculum surrounding the spicules at the distal end. An amendment of the diagnosis is proposed for the genus. [ABSTRACT FROM AUTHOR]

Based on an analysis of global digital models, the distribution of fracture zones of the oceanic crust, global and regional models of evolution, and published geological and geophysical data, the structural features of the ocean floor in the junction area of the Indian and Atlantic oceans are considered. Tectonic zoning of the region's crust has been carried out. Heterogeneous blocks of the lithosphere with crust formed on different spreading ridges, separated by structural boundaries, which are pseudofaults, fixing traces of propagating rift zones, jumping and cessation of spreading ridges are identified. The main stages in the evolution of the lithosphere associated with the activation of plume magmatism and kinematic reorganizations of plate boundaries are identified. [ABSTRACT FROM AUTHOR]

The quantitative assessment of fish larvae is a key issue in determining the composition of marine food webs. However, there is still a gap in this field regarding how to efficiently sample larvae, particularly in warm and nutrient-poor waters. We evaluated the differences found in larvae caught with two mesh size nets (330 and 500 μm) sampled in the open ocean: shelf break and slope (equatorial SW Atlantic). In total, 792 larvae were sampled, representing 14 orders and 55 families. Overall, larval density was low, and no difference in density was detected between the two net sizes (ind.100 m−3). However, a greater number of taxa (46 families) were found in the smaller net (300 μm) than in the larger (500 μm) (37). Moreover, 30.2% of families were found only in the 330 μm net, whereas 9.4% were found only in the 500 μm net. A total of 60.4% of taxa were common to both nets. Gonostomatidae, Paralepididae, Scombridae, Carangidae, Phosichthyidae, and the reef-associated families Scaridae and Gobiidae were the most abundant taxa in the smaller net. In contrast, Myctophidae, Gobiidae, Gonostomatidae, and Stomiidae were the most abundant in the larger net. We highlight mesophotic reefs and seamounts in the South Atlantic for adult spawning and larval growth, emphasizing the need for conservation actions and appropriate fisheries management. Finally, our results also indicate that the combination of different mesh net sizes provides a better baseline of fish larval diversity in warm and oligotrophic oceans. [ABSTRACT FROM AUTHOR]

Mineral dust accumulated on the ocean floor is an important archive for reconstructing past atmospheric circulation changes and climatological conditions in the source areas. Dust emitted from Southern Hemisphere dust sources is widely deposited over the oceans. However, there are few records of dust deposition over the open ocean, and a large need for extended geographical coverage exists. We present a large data set (134 surface sediment samples) of Late Holocene dust deposition from seafloor surface sediments covering the entire South Atlantic Ocean. Polymodal grain‐size distributions of the lithogenic fraction indicate that the sediments are composed of multiple sediment components. By using end‐member modeling, we attempt to disentangle the dust signal from non‐aeolian sediments. Combined with 230Th‐normalized lithogenic fluxes, we quantified the specific deposition fluxes for mineral dust, crrent‐sorted sediments and ice‐rafted debris (IRD). Although the method could not completely separate the different components in every region, it shows that dust deposition off the most prominent dust source for the South Atlantic Ocean—southern South America—amounts up to approximately 0.7 g cm−2 Kyr−1 and decreases downwind. Bottom‐current‐sorted sediments and IRD are mostly concentrated around the continental margins. The ratio of the coarse to fine dust end members reveals input from north African dust sources to the South Atlantic. The majority of the observations are in good agreement with new model simulations. This extensive and relevant data set of dust grain size and deposition fluxes to the South Atlantic could be used to calibrate and validate further model simulations. Plain Language Summary: Ocean records of mineral dust can be used to reconstruct past climatic changes such as wind strength and aridity in the source regions, and also marine biological productivity. However, in the remote open ocean, dust samples are difficult to obtain and therefore records are sparse. We present a large data set of dust deposition, determined from the top centimeter of ocean floor sediments, covering the entire South Atlantic Ocean. These appeared to be complex mixtures of different sediment types, which we attempted to unmix mathematically. This resulted in four individual components, which are fine and coarse mineral dust, current‐sorted sediments and ice‐rafted debris (IRD). Although the unmixing has its limitations, it shows that the dust deposition off the most prominent dust source for the South Atlantic Ocean—southern South America—is significant and decreases downwind as dust settles during transport across the ocean. Current‐sorted sediments and IRD are mostly concentrated around the continental margins. The results also reveal dust transport across the equator from north African dust sources and show similarities with new model simulations. This extensive and relevant data set of dust grain size and deposition fluxes to the South Atlantic can be used to calibrate and validate further model simulations. Key Points: End‐member (EM) modeling is used to disentangle different sediment components from polymodal grain‐size distributionsCombined with 230Th‐normalized lithogenic fluxes, specific fluxes for dust, current‐sorted sediments and ice‐rafted debris are obtainedThis independent quantification provides more specific dust fluxes compared to global compilations of lithogenic fluxes [ABSTRACT FROM AUTHOR]

The comparative analysis of different regions plays a pivotal role in comprehending the emerging era of intense great power competition. This article introduces the framework of Maritime Regional Security Order (MRSO), shedding light on intricate interaction patterns among local and extra-regional powers within specific geographical areas, where the nature of interactions ranges from conflict-driven to cooperative regional settings. Within this framework, the South Atlantic and the Indo-Pacific regions are examined as case studies of MRSO, both influenced by shared global dynamics that are facing heightened pressures due to escalating tensions between the United States and the People's Republic of China. The findings underscore that divergent regional forces are likely to contribute to a higher level of stability in the South Atlantic when compared to the Indo-Pacific region. [ABSTRACT FROM AUTHOR]

Three new species of the Microlaimus genus (Nematoda: Microlaimidae) are described from sample sediments collected in the South Atlantic, along the Continental Shelf break of Northeastern Brazil. Microlaimus paraundulatus sp. n. possesses four setiform cephalic sensillae, a buccal cavity with three small teeth, arched and slender spicules and a wave-shaped gubernaculum. Microlaimus modestus sp. n. is characterized by four small cephalic sensillae, a buccal cavity with three teeth (one large dorsal tooth), cephalated spicules and a strongly arched gubernaculum in the distal region. Microlaimus nordestinus sp. n. is characterized by the following set of features: relatively long body, eight rows of hypodermal glands that extend longitudinally along the body and a funnel-shaped gubernaculum surrounding the spicules at the distal end. An amendment of the diagnosis is proposed for the genus.

Microplastics (MPs) have been identified as a major potential threat to the biota and human health. Despite the exponential increase in MP research worldwide, few studies have focused on the extensive Amazon biome. To assess research priorities, the present study reviewed and summarized the available scientific knowledge on MPs in the Amazon, in addition to analyzing population and waste-management data, to evaluate potential sources of MPs in the hydrographic system. Poor sanitation conditions are a main source of MPs for the vast hydrographic basin, and, consequently, for the adjacent ocean. Secondary MPs predominated, mostly fibers (96% of debris), composed of polyamide (32%). Mean MP concentrations ranged from 0.34 to 38.3 particles.individual−1 in biota, 5 to 476,000 particles.m−3 in water, and 492.5 to 1.30848 × 107 particles.m−3 in sediment, values in close comparison with those found in areas profoundly affected by anthropogenic pollution. MPs were widespread in a range of Amazonian environments and species, and negative effects are probably occurring at various ecological levels. However, limited research, methodological constraints, flaws and the lack of standardization, combined with the continental dimensions of the Amazon, hampers the collection of the fundamental knowledge needed to reliably evaluate the impacts and implement effective mitigation measures. There is an urgent need to expand scientific data available for the region, improving local research infrastructure, and training and deploying local researchers.

The climate in the South Atlantic sector of the sub-Antarctic, and therefore on and around the island of South Georgia, is dependent on the Southern Hemisphere Westerlies (SHW) and the Antarctic Circumpolar Current (ACC). The SHW and the ACC, in turn, are strongly controlled by climate variability in the Southern Hemisphere. Accordingly, thick sediment sequences in the troughs across South Georgia's continental shelf serve as valuable archives for past climate variations in the Southern Ocean. Since Holocene climate fluctuations led to only minimal oscillations in glacier margin positions within the fjords, the entire shelf was exposed to dynamic ocean currents since at least 10 ka BP. Its depositional systems are therefore a suitable target for the reconstruction of Holocene dynamics of both the SHW and the ACC. Sub-bottom profiler data and radiocarbon ages from four gravity cores from the south-western South Georgia continental shelf provide evidence for a complex interplay between island run-off and ocean currents intruding into a unique cross-shelf trough system during the last ∼10 ka. The data reveal several prominent changes in sediment and Holocene climate dynamics, the most significant occurring between 8 and 7.7 cal ka BP and between 2.6 and 2.2 cal ka BP. Both of these time periods represent transitions from warmer to cooler and windier conditions in South Georgia and the Southern Hemisphere. Our record from the King Haakon Trough System is the first highly resolved Holocene archive from the marine realm on the south-western South Georgia continental shelf and suggests several large-scale Southern Hemisphere climate changes during the mid-to late Holocene.

This article examines the profound consequences of the global upheavals of the first decades of the 19th century on the Kongo kingdom, notably the abolitionist phenomenon of the slave trade, and the Independence of Brazil. Our aim is to analyze how Kongo kings, princes and officers tried to maneuver in these troubled times and adapt to a context that challenged the old diplomatic and economic modus operandi between Kongo and Portugal. These new power relations and the attempts of the Kongo elites to keep their power and sovereignty led to misunderstandings and violent situations. We will analyze a specific case study: that of Kongo prince Aleixo Água Rosada – emblematic and revealing of the strength of the process underway and its impact on Kongo at the dawn of colonialism.

Abstract Aerosols have implications to climate and biogeochemical cycles in the global oceans. At sites under indirect influence of dust emitted by the Patagonian semi-desert, a debate exists on the potential fertilization effects of iron enriched aerossol. Considering this subject we conducted measurements of aerosols optical properties using a Microtops II sun photometer to access aerosol size distributions and other intrinsic properties oversea from Atlantic Southern mid-latitudes to Antarctica. Oceanographic cruises were developed between December 2010 to April 2011 and October 2011 to April 2012, in the context of the Brazilian Antarctic Program, and between November 2011 to December 2011. This survey was taken as part of the Global Maritime Aerosol Network (MAN/NASA). Our data of AOD (500 nm) along the South American coast depicts a steady decrease southwards following the decreased latitudinal continental extent. However, the influence of the aerosols blown from Patagonia semi-desert region was clear from latitude 53⁰S to 64⁰S. The predominance of aerosol fine mode was observed in Central Atlantic and close to the Drake Passage. An unexpected aerosol coarse mode predominance was found close to the Antarctic Peninsula. We attribute that to a possible weathering of rock outcrops due to the strong westerly winds in that region.

The Araçuaí Orogen, in eastern Brazil, was formed during the Neoproterozoic – Cambrian amalgamation of West Gondwana. During the Mesozoic – Cenozoic opening of the South Atlantic Ocean, and the associated divergent tectonics, the orogen developed as basement to the passive margin of South America and was progressively covered by thick offshore sedimentary basins, particularly the Espírito Santo, Mucuri, and Cumuruxatiba basins, in which hydrocarbon systems have been exploited. Our understanding of the Araçuaí Orogen's passive margin evolution, erosion, and sediment transfer to these basins ultimately depends on constraining the onshore exhumation in response to Mesozoic – Cenozoic events. Here, new and previously published data from apatite fission-track (AFT) analyses and inverse thermal history modelling of (Pre)Cambrian basement rocks from the Araçuaí Orogen resolve three discrete basement cooling and associated erosional exhumation episodes. In the Pre-Rift phase, Jurassic – Hauterivian erosion of the Araçuaí Orogen is most likely related to the adjoining intra-continental West Gondwana flexural subsidence, which increased hillslope and river erosion power. In the Rift and Transitional phases, Barremian – Albian accelerated phase of erosion is associated with the uplift of the Atlantic rift shoulders and the establishment of an oceanic base-level. In the Drift phase, reactivations in response to far-field stresses likely triggered a Late Cretaceous – Paleocene rapid erosion event. The rates at which these events unfolded vary spatially and are controlled by inherited structures. The Araçuaí Orogen experienced slower denudation rates in areas closer to the São Francisco Craton, which suggests that the tectonic reactivation and related surface uplift during the Mesozoic–Cenozoic is in first-order controlled by lithospheric rigidity. Furthermore, the structural framework of the Paramirim and Pirapora aulacogens and NE-oriented shear zones in the orogen’s southeast facilitated later reactivations. From the spatial pattern of denudation/exhumation of the Araçuaí Orogen during the Mesozoic – Cenozoic, we draw inferences on the tectonic development of the offshore basins regarding their hydrocarbon potentials.

The results of density modeling of the tectonosphere structure in the Antarctic sector of the South Atlantic Ocean are presented. The modeling was carried out along the profiles stretching from the Falkland Plateau to the Mozambique Ridge and crossing a series of submarine rises and ridges separated by deep-sea basins. Studies show that the crust of this region has a heterogeneous structure and the crust underlying the rises is of a different structure, indicating different origins of the respective rises. [ABSTRACT FROM AUTHOR]

The high number of bipolar and widespread bryophyte and microbial taxa in the Antarctic flora suggests the effective Long‐Distance Dispersal (LDD) of spores and other propagules from lower latitudes and even the Northern Hemisphere to Antarctica and the sub‐Antarctic regions. However, few studies have attempted to document the transfer mechanisms by which potential newcomers may arrive in Antarctica. Commonly suggested or assumed mechanisms include transport in air currents, adventitious transfer with migrating or vagrant birds, and with human assistance. In this study, we investigated the biodiversity present in the air along a 40° latitudinal transect, from the port city of Rio de Janeiro, Brazil (ca. 22°S) to Comandante Ferraz Station on King George Island (South Shetland Islands, ca. 62°S), maritime Antarctica, to shed light on the potential role of LDD in species distribution. Air samples were collected in October 2021 on the Brazilian polar support vessel Ary Rongel using air filters with membranes of 0.22 μm. Total DNA was extracted from the filters and the Internal Transcribed Spacer (ITS2) DNA sequence was used for metabarcoding. A total of 53 non‐fungal taxa representing three kingdoms (most abundantly Viridiplantae) and six phyla (most abundantly Bryophyta and Magnoliophyta) were assigned from the sequences found. Aerial biodiversity was greater closer to the coast and generally decreased with increasing latitude, although a small increase was apparent in the South Shetland Islands. The taxa assigned are generally present in coastal biomes, although a small proportion of the assignments represented taxa of more distant origin, supporting the occurrence of LDD in the air column. [ABSTRACT FROM AUTHOR]

Lumbrineriopsis dulcis sp. nov. is morphologically described from the continental shelf and slope of Espírito Santo and the Campos Basin of Rio de Janeiro state, southeastern Brazil, at depths between 14 and 400 m. Lumbrineriopsis mucronata is the only species of the genus recorded until now in Brazil. The new species differs from other congeneric species in its jaw-apparatus morphology with unfused mandibles and a fixed number of simple limbate chaetae and simple, bidentate, hooded hooks in each parapodium. This paper aims to fill the gap in knowledge on the family Lumbrineridae, which has not been studied in Brazil for the last 25 years and provides the first record of the genus from Espírito Santo and Rio de Janeiro states. This record is significant given the damage to the marine ecosystem of the Espírito Santo region due to the 2015 rupture of the Samarco mining company dam, the largest environmental disaster in Brazil's history. In addition, this region has important environmental conservation units such as Costa das Algas Environmental Protection Area, Santa Cruz Wildlife Refuge, and Comboios Biological Reserve. All these preserved areas are of paramount importance for the protection of marine biological diversity. [ABSTRACT FROM AUTHOR]

The better understanding of the initial rifting would complement the knowledge of continental breakup and the oceanic opening process. Traditionally, mechanisms controlling the initial rifting have been divided into two schools of end-member models, magma-rich vs magma-poor rifting and pure-shear vs simple shear rifting. However, the linkage between these two schools has been rarely addressed. In our study, extension magnitude and ratio obtained from the balanced cross-sections were applied in magma-poor and magma-rich segments in South Atlantic margins to establish the possible linkage, as classic pure-shear and simple-shear models predict different extension magnitudes and ratios. Two pairs of structural sections Campos basin‒Kwanza basin from the central segment and Pelotas basin‒Walvis basin from the south segment, the southern segment temporally and spatially related to the (Paraná‒Etendeka Large Igneous Province) were subjected to balanced cross-section analysis to determine the extension magnitudes and ratios at the initial rifting stage predating finally opening of South Atlantic Ocean. Comparing the results in the South Atlantic margins with those obtained in classic shear models may suggest the magma-rich segment would return a larger extension ratio and possibly prefer to pure-shear rifting. Results of this study might build a likely linkage between the magma-rich and pure-shear mechanisms during the initial rifting of the oceanic opening process. [ABSTRACT FROM AUTHOR]

We explore the South Atlantic as a moisture source for South America and its relationship with the precipitation variability in southeastern South America (SESA) during the 1982–2015 period. Based on diagnostic calculation with a Semi-Lagrangian analytical model, three regions of the South Atlantic acting as moisture sources for South America were studied: the Tropical Atlantic (15° N–5° S), Subtropical Atlantic (30° S–5° S), and Southwestern Atlantic (21° S–50° S; 30° W to the further west). The Tropical and Subtropical Atlantic are important sources of moisture for the Amazon, and occasionally for SESA. The Southwestern Atlantic contributes mainly locally, although in summer it also has a role in increasing precipitation over Uruguay and southern Brazil. Approximately 17% of the observed precipitation over the La Plata basin comes from the three regions identified as moisture source in the South Atlantic. Sea surface temperature variability is related to the moisture contribution from the South Atlantic to the continent. In summer, a significant positive correlation between the sea surface temperature leading-mode and the precipitation contribution from the Tropical Atlantic and La Plata Basin is found. A significant negative correlation between the sea surface temperature leading-mode and contribution in terms of precipitation from the Southwest Atlantic was found, as warm anomalies are associated with an anomalous cyclonic circulation over the Southwest Atlantic that favors moisture transport to SESA. Finally, the study of individual precipitation events identified contributions from the Subtropical and Southwest Atlantic to particular daily precipitation events in SESA. Climatological contributions from the Southwestern Atlantic are low, however, in events such as these, their contribution can increase up to 40% on the synoptic scale. [ABSTRACT FROM AUTHOR]

Monthly climatology data for salinity fronts in the South Atlantic have been created from satellite SMOS sea surface salinity (SSS) measurements taken from 2011–2019, processed at the Barcelona Expert Center of Remote Sensing (BEC), and provided as high-resolution (1/20°) daily SSS data. The SSS fronts have been identified with narrow zones of enhanced horizontal gradient magnitude (GM) of SSS, computed using the Belkin–O’Reilly algorithm (BOA). The SSS gradient fields generated by the BOA have been log-transformed to facilitate feature recognition. The log-transformation of SSS gradients markedly improved the visual contrast of gradient maps, which in turn allowed new features to be revealed and previously known features to be documented with a monthly temporal resolution and a mesoscale (~100 km) spatial resolution. Monthly climatologies were generated and analyzed for large-scale open-ocean SSS fronts and for low-salinity regions maintained by the Rio de la Plata discharge, Magellan Strait outflow, Congo River discharge, and Benguela Upwelling. A 2000 km-long triangular area between Africa and Brazil was found to be filled with regular quasi-meridional mesoscale striations that form a giant ripple field with a 100 km wave length. South of the Tropical Front, within the subtropical high-salinity pool, a trans-ocean quasi-zonal narrow linear belt of meridional SSS maximum (Smax) was documented. The meridional Smax belt shifts north–south seasonally while retaining its well-defined linear morphology, which is suggestive of a yet unidentified mechanism that maintains this feature. The Subtropical Frontal Zone (STFZ) consists of two tenuously connected fronts, western and eastern. The Brazil Current Front (BCF) extends SE between 40 and 45°S to join the subantarctic front (SAF). The STFZ trends NW–SE across the South Atlantic, seemingly merging with the SAF/BCF south of Africa to form a single front between 40 and 45°S. In the SW Atlantic, the Rio de la Plata plume migrates seasonally, expanding northward in winter (June–July) from 39°S into the South Brazilian Bight, up to Cabo Frio (23°S) and beyond. The inner Plata front moves in and out seasonally. Farther south, the Magellan Strait outflow expands northward in winter (June–July) from 53°S up to 39–40°S to nearly join the Plata outflow. In the SE Atlantic, the Congo River plume spreads radially from the river mouth, with the spreading direction varying seasonally. The plume is often bordered from the south by a quasi-zonal front along 6°S. The diluted Congo River water spreads southward seasonally down to the Angola–Benguela Front at 16°S. The Benguela Upwelling is delineated by a meridional front, which extends north alongshore up to 20°S, where the low-salinity Benguela Upwelling water forms a salinity front, which is separate from the thermal Angola–Benguela Front at 16°S. The high-salinity tropical water (“Angola water”) forms a wedge between the low-salinity waters of the Congo River outflow and Benguela Upwelling. This high-salinity wedge is bordered by salinity fronts that migrate north–south seasonally.

The type material of three species of the endemic genus TecutionBenoit, 1977 on Saint Helena are re-examined. Tecution helenicolaBenoit, 1977syn. nov. and Tecution mellissi (O. Pickard-Cambridge, 1873) syn. nov. are synonymized with Tecution planum (O. Pickard-Cambridge, 1873), based on identical palpal morphology and the discovery of a gradient of cheliceral size variation in a large amount of non-type material from Saint Helena Island. A brief discussion on the habitat and ecology of T. planum is provided. [ABSTRACT FROM AUTHOR]

Results of numerical experiments on the assimilation of in situ temperature and salinity profiles observed in the region of Drake Passage (the South Atlantic) during the expedition of Shirshov Institute of Oceanology of Russian Academy of Sciences (RAS) in the autumn of 2011 into the INMOM model developed by Marchuk Institute of Numerical Mathematics of RAS are considered. The previously developed method of assimilation presented in several publications is used. As a result of some experiments, it has been shown that the structure of the anticyclonic circulation associated with the Brazil-Malvinas Confluence in the area of the Argentine Basin has been mostly affected by the expedition data assimilation. Assimilated fields of ocean temperature on the surface and at various horizons show better agreement with reanalysis data than corresponding fields without assimilation. It is also demonstrated that the influence of assimilation spreads much further beyond the local area of observations and leads to changing all calculated characteristics (not only observed ones). [ABSTRACT FROM AUTHOR]

The kinematic reorganization of plate boundaries in the southeastern Antarctic part of the South Atlantic, expressed in the jump of the spreading axis of the Agulhas Ridge, led to a restructuring of the region's structural plan. This resulted in the formation of the southern segment of the Mid-Atlantic Ridge (MAR), extinction of the previously active Agulhas spreading ridge, and formation of the Meteor and Islas Orcadas rises, marking the location of the MAR and located symmetrically about its axis. Based on the research results, the conditions for the jump in the spreading axis were identified and an experimental model was constructed for the formation of accompanying structures, in which an important role was played by the accretion of oceanic crust on the Agulhas Ridge and westward migration of the Falkland Plateau. This resulted in southward movement of the southern segment of the MAR, formation of the Malvinas microplate, and a jump in the axis of the Agulhas spreading ridge, which led to cessation of spreading on this ridge. An important role in this kinematic restructuring was played by activity of the Shona hotspot. [ABSTRACT FROM AUTHOR]

The life history and oceanic impact of three very large icebergs that escaped together from the Weddell Sea sea ice, near the tip of the Antarctic Peninsula, are traced from March 2014. Despite the initial proximity of these three icebergs, they followed very different trajectories across the South Atlantic until their eventual break-up and melting 1 year later. The largest, giant iceberg, B17a, spent extensive periods grounded near two different islands. The triplet's gradual melting is examined through the impact on the icebergs' dimensions, but also the meltwater's oceanic influence on the local salinity and primary productivity. It is found that there was generally a significant local surface and mixed-layer freshening of a few tenths of a practical salinity unit, up to several hundred kilometres away from the 10–20 km-sized icebergs. In contrast, the chlorophyll impact was highly temporally variable, although it tended to be larger in the summer. Break-up of these large icebergs did not occur until near the end of their life. We also show that modelling the trajectories of individual very large icebergs can be reasonable for up to 2 weeks if the characteristics of the iceberg and the local ocean and atmospheric forcing are well known. [ABSTRACT FROM AUTHOR]

Fin whales Balaenoptera physalus were hunted unsustainably across the globe in the 19th and 20th centuries, leading to vast reductions in population size. Whaling catch records indicate the importance of the Southern Ocean for this species; approximately 730,000 fin whales were harvested during the 20th century in the Southern Hemisphere (SH) alone, 94% of which were at high latitudes. Genetic samples from contemporary whales can provide a window to past population size changes, but the challenges of sampling in remote Antarctic waters limit the availability of data. Here, we take advantage of historical samples in the form of bones and baleen available from ex-whaling stations and museums to assess the pre-whaling diversity of this once abundant species. We sequenced 27 historical mitogenomes and 50 historical mitochondrial control region sequences of fin whales to gain insight into the population structure and genetic diversity of Southern Hemisphere fin whales (SHFWs) before and after the whaling. Our data, both independently and when combined with mitogenomes from the literature, suggest SHFWs are highly diverse and may represent a single panmictic population that is genetically differentiated from Northern Hemisphere populations. These are the first historic mitogenomes available for SHFWs, providing a unique time series of genetic data for this species. [ABSTRACT FROM AUTHOR]

This essay revisits the argument, purposes, and steps that led to the publication of my book on the formation of Brazil in the South Atlantic, also taking stock of its impact and reception over the last 20 years. Brazilian historiography is generally linked to a territorial paradigm that could be summarized in a false axiom: the colonial history of Brazil unfolds only in the colonial territory of Brazil. My studies in France, when the Annales were still promoting the global history of Braudel and his disciples, helped me to escape this bias at a time when more comprehensive studies on the transatlantic slave trade were published.

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Species overlapping in habitat use can cohabit depending on how they exploit resources. To understand segregation in resource use, an exhaustive knowledge of the diet is required. We aimed to disentangle the diet composition of the Falkland Flightless Steamer Duck Tachyeres brachypterus and the Patagonian Crested Duck Lophonetta specularioides sharing a coastal environment. Using DNA extracted from scats and Illumina sequencing, we generated a list of molecular operational taxonomic units. Both ducks consumed a variety of invertebrates, frequently overlapping in the taxa consumed. However, only the Falkland Flightless Steamer Ducks consumed fish, which might be indicative of dietary specialization and inter-specific segregation in the restricted space that these birds share. Moreover, the female and male Falkland Flightless Steamer Ducks consumed different fish prey, with almost one-third of the fish taxa being consumed by females only and another similar number consumed by males only. This result might suggest a case of intra-specific competition, triggering sexual segregation. Additionally, we detected parasitic Platyelminthes (Cestoda and Trematoda), with different frequencies of occurrence, probably related to the different diet compositions of the ducks. This study provides the necessary baseline for future investigations of the ecological segregation of these ducks. [ABSTRACT FROM AUTHOR]

The Zone of Peace and Cooperation of the South Atlantic (ZOPACAS) is a maritime zone of peace that was established, largely through Brazilian efforts, by the UN General Assembly in 1986. Since its establishment, ministerial meetings have been convened to discuss the zone's evolving agenda, which has focused on maintaining peace, building diplomatic and defence cooperation between its twenty-four member states, and encouraging development in the South Atlantic region. This article examines Brazilian diplomatic and defence interests in the South Atlantic, providing an analysis of sections in Brazil's official defence documents (1994–2020), pertaining to the ZOPACAS, South-South cooperation, development and regional security. It ultimately seeks to address how efforts behind a new revitalisation of the ZOPACAS are being driven by the Brazilian military with the aim of expanding Brazil's defence framework in the South Atlantic. [ABSTRACT FROM AUTHOR]

The Brazilian continental margin (BCM) extends from the Tropical to the Subtropical Atlantic Ocean, with much of its seafloor within deep waters, supporting rich geomorphological features and under wide productivity gradients. Deep-sea biogeographic boundaries on the BCM have been limited to studies that used water mass and salinity properties of deep-water masses, partly as a result of historical under sampling and a lack of consolidation of available biological and ecological datasets. The aim of this study was to consolidate benthic assemblage datasets and test current oceanographic biogeographical deep-sea boundaries (200-5,000 m) using available faunal distributions. We retrieved over 4,000 benthic data records from open-access databases and used cluster analysis to examine assemblage distributions against the deep-sea biogeographical classification scheme from Watling et al. (2013). Starting from the assumption that vertical and horizontal distribution patterns can vary regionally, we test other schemes incorporating latitudinal and water masses stratification within the Brazilian margin. As expected, the classification scheme based on benthic biodiversity is in overall agreement with the general boundaries proposed by Watling et al. (2013). However, our analysis allowed much refinement in the former boundaries, and here we propose the use of two biogeographic realms, two provinces and seven bathyal ecoregions (200-3,500 m), and three abyssal provinces (>3,500 m) along the BCM. The main driver for these units seems to be latitudinal gradients as well as water mass characteristics such as temperature. Our study provides a significant improvement of benthic biogeographic ranges along the Brazilian continental margin allowing a more detailed recognition of its biodiversity and ecological value, and also supports the needed spatial management for industrial activities occurring in its deep waters. [ABSTRACT FROM AUTHOR]

The South Atlantic Ocean Dipole (SAOD) exerts strong influence on climate variability in parts of Africa and South America. Here we assess the ability of an ensemble of 35 state-of-the-art coupled global climate models to simulate the SAOD impacts on regional rainfall for the historical period (1950–2014), and their future projections (2015–2079). For both periods we consider the peak phase of the dipole in austral winter. Observational analysis reveals four regions with spatially coherent SAOD impacts on rainfall; Northern Amazon, Guinea Coast, Central Africa, and Southeast Brazil. The observed rainfall response to the SAOD over Northern Amazon (0.31 mm d ^−1 ), Guinea Coast (0.38 mm d ^−1 ), and Southeast Brazil (0.12 mm d ^−1 ) are significantly underestimated by the modeled ensemble-mean response of 0.10 ± 0.15 mm d ^−1 , 0.05 ± 0.15 mm d ^−1 , −0.01 ± 0.04 mm d ^−1 , respectively. A too southerly rain belt in the ensemble, associated with warmer-than-observed Atlantic cold tongue, leads to better performance of models over Central Africa (46% simulate observations-consistent SAOD-rainfall correlations) and poor performance over the Guinea Coast (only 5.7% simulate observations-consistent SAOD-rainfall correlations). We also find divergent responses among the projections of ensemble members precluding a categorical statement on the future strength of the SAOD-rainfall relationship in a high-emissions scenario. Our results highlight key uncertainties that must be addressed to enhance the value of SAOD-rainfall projections for the affected African and South American countries.

Even though oceans are pivotal for the non-proliferation of nuclear weapons, they constitute a blind spot in the global non-proliferation regime. This article analyses how regional security governance mechanisms may fill such gaps by bringing a maritime focus to non-proliferation studies. With three nuclear-weapons-free zones and one zone of peace surrounding or covering its maritime space, the South Atlantic serves as an illustrative case to understand the provision of security governance for the seas. The article identifies a range of legal, political, and practical challenges that can impede regional initiatives from achieving security sovereignty over maritime spaces. However, while non-proliferation might remain precarious, these mechanisms are not without success, as they serve to establish the opposition to nuclear weapons as a recognised norm, both at the UN level and among the Global South. The narrative of non-proliferation also allows regional states to justify the pursuit of security objectives. The article concludes by outlining the conditions for regional maritime governance to become more effective in terms of non-proliferation.