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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.

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.

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]

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]

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]

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]

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]

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 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]

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.

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]

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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]

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.

Palynological investigations in the Sumbe region of the Kwanza Basin, Angola, have identified Albian to Turonian assemblages in four sections of the Quissonde Facies of the Mucanzo, Cabo Ledo, and Itombe formations. These studies aimed to determine their biostratigraphic ages and infer paleoenvironmental, paleoclimatic, and paleogeographic models. The presence of Odontochitina costata, Palaeohystrichophora infusorioides, and Xiphophoridium alatum cysts supports an upper Albian to lower Cenomanian age for the Mucanzo Formation. Litosphaeridium siphoniphorum cyst and the Elateroplicites africaensis pollen found In the Cabo Ledo Formation suggest a Cenomanian age, while Conosphaeridium striatoconum, Heterosphaeridium difficile, and Dinogymnium acuminatum supports a Turonian age for the lower part of the Itombe Formation. All samples predominantly contain fluorescent amorphous organic matter (AOM) derived from phytoplankton degradation, with increasing AOM in the uppermost units, indicating inner neritic marine deposition under dysoxic-anoxic conditions. During the Lower to mid-Cretaceous, the Gondwana breakup caused significant changes, with the palynological indicating a Tethyan affinity with some high-latitude taxa, suggesting a cosmopolitan distribution. The subtropical to tropical nature of the assemblages, along with high-latitude species, indicates a mid-Cretaceous water connection between the Central Atlantic and the South Atlantic oceans, extending to the Kwanza Basin. • Palynological assemblages from the Sumbe region, Kwanza Basin were analysed. • Palynoflora and palynofacies analysis were performed. • Palynomorph assemblages ranging from the late Albian to the Turonian age. • Palynofacies suggests an inner marine deposition, under dysoxic-anoxic conditions. • A predominant Tethyan influence was recorded. [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.

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 level of habitat availability influences genetic divergence among populations and the genetic diversity within populations. In the marine environment, near-shore species are among the most sensitive to habitat changes. Knowledge of how historical environmental change affected habitat availability and genetic variation can be applied to the development of proactive management strategies of exploited species. Here, we modeled the contemporary and historical distribution of Lutjanus jocu in Brazil. We describe patterns of genomic diversity to better understand how climatic cycles might correlate with the species demographic history and current genetic structure. We show that during the Last Glacial Maximum, there were ecological barriers that are absent today, possibly dividing the range of the species into three geographically separated areas of suitable habitat. Consistent with a historical reduction in habitat area, our analysis of demographic changes shows that L. jocu experienced a severe bottleneck followed by a population size expansion. We also found an absence of genetic structure and similar levels of genetic diversity throughout the sampled range of the species. Collectively, our results suggest that habitat availability changes have not obviously influenced contemporary levels of genetic divergence between populations. However, our demographic analyses suggest that the high sensitivity of this species to environmental change should be taken into consideration for management strategies. Furthermore, the general low levels of genetic structure and inference of high gene flow suggest that L. jocu likely constitutes a single stock in Brazilian waters and, therefore, requires coordinated legislation and management across its distribution. [ABSTRACT FROM AUTHOR]

Studies relating the populational structure of target species to operational and environmental variables contribute directly to the management of the fisheries in these resources. Therefore, this study aimed to provide data on fishing and ecology of the swordfish (Xiphias gladius) caught by the Brazilian longline fleet operating in the western Atlantic between 2010 and 2016. Generalized additive mixed models were used to evaluate the relationship between explanatory variables and responses based on Catch Per Unit of Effort (CPUE) data. Results show that the Brazilian longline fleet catches the swordfish mostly between latitudes of 5°N to 30°S and longitudes of 20° to 50°W and that the swordfish prefers temperatures under 25°C at depths below 60 meters. The species showed a tendency toward intermediate light intensity, predominating in the crescent moon phase, and a preference for areas with low chlorophyll concentrations. Our findings on operational and environmental interactions with swordfish CPUE suggest areas and times that can be used by fishing fleets and government institutions as a starting point for swordfish management strategies. [ABSTRACT FROM AUTHOR]

The brittle stars of the family Ophiocomidae inhabit shallow waters and coral reefs of tropical regions. The species of Ophiocoma are difficult to identify due to high morphological variation, especially when different stages of development are observed. Here, based on morphological analyses, two Brazilian morphotypes of Ophiocoma were studied and characterized, Ophiocoma sp. NB (Northeastern Brazil) and Ophiocoma sp. TMV (Trindade and Martin Vaz Archipelago), and subsequently thoroughly analysed to confirm whether they were the same species or not. After the morphological studies, including external morphology, morphometry and microstructural characters, and analysis of molecular data, involving the 16S gene, it was concluded that Ophiocoma sp. NB and Ophiocoma sp. TMV do not correspond to the same species, the first being identified as Ophiocoma echinata (Lamarck, 1816) and the latter being a new species. This new species is characterized by two tentacle scales on the first arm segment and then one on all following segments, and the dorsalmost arm spines are robust and rounded, as wide as long or almost as wide as long. [ABSTRACT FROM AUTHOR]

The paper presents the results of U–Pb SHRIMP-II dating and isotope-geochemical data on zircon xenocrysts extracted from igneous rocks of the Shaka Ridge, South Atlantic. We compared the obtained data and the results of studying young "oceanic" zircons from rocks of the Atlantis Bank, Central Atlantic. The age of xenogenic zircon grains, recorded in the U–Pb isotope system, changes from Proterozoic (ca. 1.1 Ga) to Mesozoic (ca. 180 Ma). Zircon possesses geochemical characteristics of igneous origin: The Th/U ratio is from 0.01 to 19.4 and REE distribution spectra differentiated from light to heavy lanthanides with pronounced positive Ce and negative Eu anomalies. In the discrimination diagrams showing ratios between Yb, U, and Y, the studied zircon falls within the field of continental crustal rocks, including the field of continental granitoids. The crustal source of zircon xenocrysts is also suggested by the higher Li content in zircon. The data on oxygen isotope composition in zircon indicate either the presence of crustal signatures or probable hydrothermal effect. Most likely, the results indicate the multiplicity of sources from which zircon xenocrysts were transported. [ABSTRACT FROM AUTHOR]

Previous works used marine magnetic survey data and interpreted magnetic anomalies related to seaward‐dipping reflectors (SDRs) as oceanic crust or SDR age constraints in the South Atlantic Ocean. However, we advise against using SDR‐related magnetic anomalies to constrain ages because of the mostly low‐dipping geometry causing the overlapping of rocks extruded during periods of different polarities. The data are difficult to interpret correctly because of the SDR compositional heterogeneity, sedimentary intercalations, variations in package thickness with different compositions and magnetic polarities, and the absence of a link between the SDR magmatic position and age. SDR‐related magnetic anomalies are mainly caused by magnetic susceptibility contrasts rather than remanent magnetism. Due to this complexity, the SDR geometry and variable composition make SDR‐related magnetic anomalies challenging to use for age constraints. The Pelotas Basin SDRs age cannot be estimated by magnetostratigraphy, and this method likely cannot constrain the age of any SDR wedge. Plain Language Summary: Since the 1960s, an increased understanding of oceanic crust chronology has quickly evolved into a field of study called magnetostratigraphy. Basaltic lavas extruded in a certain time interval acquire a positive or negative magnetic polarity according to the magnetic polarity on Earth during the extrusion. From the mid‐ocean ridge to the continental oceanic boundary, the continuous and progressive accretion of the oceanic crust provides age constraints for the sea bottom. However, on volcanic passive margins, the presence of volcanic rocks with wedge geometries is abundant. These volcanic rocks are called seaward‐dipping reflectors (SDRs) because of their wedge‐shaped geometry toward the ocean and are usually identified by seismic reflection surveys. The presence of these volcanic wedges makes the identification of the oceanic–continental crustal boundary a challenging task. Some magnetic anomalies that some researchers state as related to a regular vertical oceanic crust are SDR‐related. The SDR‐related magnetic anomalies are not related to that age because SDR‐related magnetic anomalies are mainly caused by magnetic susceptibility contrasts rather than remanent magnetism. We used seismic lines and magnetic data from the Pelotas Basin to illustrate how these magnetic anomalies are not age‐related. Key Points: Some magnetic anomalies interpreted as related to vertical fabric oceanic crust are related to seaward‐dipping reflectors (SDRs)Seaward‐dipping reflectors are different from typical oceanic crust in geometry and compositional heterogeneitySDR‐related magnetic anomalies should not be used to constrain ages [ABSTRACT FROM AUTHOR]

Paracalanid copepods, common in tropical zooplankton communities, are known hosts for a variety of parasites. Nevertheless, relatively little is known about the prevalence and consequences of parasitism in these copepods. In this study, we analyzed the relationship between two paracalanid copepods, Parvocalanus crassirostris and Paracalanus spp., with a common parasite, the alveolate protist Ellobiopsis chattoni, in a subtropical environment on the south-east Brazilian coast. We assessed the frequency and abundance of parasites in juveniles and adult male and female copepods. We observed that 22 out of 4014 Paracalanus spp. (0.55%) and 98 out of 3920 P. crassirostris were infected (2.5%). E. chattoni were rarely found in other taxa (about 0.05% for Oithona spp. and Acartia lilljeborgii). The parasites were most frequently attached to cephalosome appendages (73.6%), with up to four cells per copepod. The parasites were more prevalent in adults than juveniles, and adult females were more frequently infected than males. E. chattoni had a likely negative impact on copepod growth because the infected females were smaller than the non-infected females (p < 0.001). Females are usually bigger and live longer than males, which could account for their high frequency of infection. [ABSTRACT FROM AUTHOR]

Coral reef ecology has advanced in many fields, but disease patterns across depth gradients remain unclear. By comparing the prevalence and extent of bleaching and diseases in 160 colonies of Siderastrea stellata between shallow and mesophotic reefs, we observed that prevalence was high (75%) regardless of depth, but the extent was about two times greater in mesophotic than shallow reefs (14.4% vs. 6.6% of colony area, respectively). Across the shallow reefs, where S. stellata co-occurred with Montastraea cavernosa, M. cavernosa showed lower prevalence (27% of 30 colonies) and extent (1.8% of colony area) compared to S. stellata. Besides bleaching, five coral diseases afflicted S. stellata and two affected M. cavernosa. Because diseases are spread over the entire gradient of depth, any attempt of managing the diseases should consider both shallow and deep reefs to be effective. [ABSTRACT FROM AUTHOR]

Gelatinous animals have been historically viewed as trophic dead-ends. However, there are increasing data showing these organisms being consumed by diverse predators and demonstrate they play an important role in ecosystem functioning. Here we document the Ocypode quadrata (Fabricius, 1787) scavenging on stranded Physalia physalis (Linnaeus, 1758) at Sergipe and Bahia, tropical Brazil (11° and 14° Lat. S), based on Instagram® posts. These findings highlight the potential of social media to complement the information provided by traditional academic sources. We also suggest that this predatory interaction is probably more common than reported in the literature, perhaps due to methodological constraints of stomach content analyses, which may overlook the consumption of gelatinous animals by ghost crabs. [ABSTRACT FROM AUTHOR]

The lithospheric architecture of passive margins is crucial for understanding the tectonic processes that caused the breakup of Gondwana. We highlight the evolution of the South Atlantic passive margins by a simple thermal lithosphere‐asthenosphere boundary (LAB) model based on onset and cessation of rifting, crustal thickness, and stretching factors. We simulate lithospheric thinning and select the LAB as the T = 1,330°C isotherm, which is calculated by 1D advection and diffusion. Stretching factors and margin geometry are adjusted to state‐of‐the‐art data sets, giving a thermal LAB model that is especially designed for the continental margins of the South Atlantic. Our LAB model shows distinct variations along the passive margins that are not imaged by global LAB models, indicating different rifting mechanisms. For example, we model up to 200 km deep lithosphere in the South American Santos Basin and shallow lithosphere less than 60 km in the Namibe Basin offshore Africa. These two conjugate basins reflect a strong asymmetry in LAB depth that resembles variations in margin width. In a Gondwana reconstruction, we discuss these patterns together with seismic velocity perturbations for the Central and Austral Segments of the margins. The shallow lithosphere in the Namibe Basin correlates with signatures of the Angola Dome, attributed to epeirogenic uplift in the Neogene, suggesting an additional component of post‐breakup lithospheric thinning. Plain Language Summary: Passive margins mark the transition zone from a continent to the ocean without being an active boundary of tectonic plates. They are typical for all continents on the globe. In the South Atlantic, the passive margins are located adjacent to the eastern coastline of South America and the western coastline of Africa. Studying the architecture of passive margins is essential for understanding plate tectonic history of the earth because they define how the continents once fitted together and how they broke apart. Passive margin segments on opposite sides of an ocean form so called conjugate margin pairs. Most geophysical studies of passive margins focus on the first few kilometers under the surface. However, their deeper extension to the base of the rigid shell of the earth, known as lithospheric thickness, is to a large extent unknown. Based on a simple temperature model, we find that the lithospheric thickness is highly variable and shows large variations along the South Atlantic passive margins. These differences are associated with the extension of conjugate margin pairs: where one margin is narrower than the conjugate, its lithospheric thickness is greater. This asymmetry indicates that the geodynamic processes, causing the breakup of the two continents, must have been asymmetric as well. Offshore Angola, the lithosphere is modeled shallow and matches with relatively young rock signatures. This suggests additional tectonic activity on the African side after the breakup between the two continents occurred. Key Points: A simple thermal lithosphere‐asthenosphere boundary (LAB) model for the South Atlantic passive margins has been developedThe LAB model shows distinct variations along the margins that correlate with margin widthsConjugate margin pairs reflect an asymmetry in LAB depth patterns that are locally related to post‐breakup lithospheric thinning [ABSTRACT FROM AUTHOR]

The Agulhas rings transport warm and salty waters that feed the surface limb of the Atlantic Meridional Overturning Circulation. Some studies have focused on the conveying capacity of ocean eddies, and recently, the role of the Agulhas rings in advecting water masses and organisms has been explored. Here we show evidence that the Agulhas rings are responsible for the advection of mode waters from the Cape Basin to the western side of the Atlantic. We analyzed more than 3,200 temperature profiles and 2,400 salinity profiles from historical databases collocated with 52 long-lived Agulhas rings tracked from 1993 through 2016. An automated algorithm was used to identify thermostads in the profiles acquired within the rings. The data revealed mode water layers trapped inside 88% of the rings. The joint distribution of temperature and salinity indicated two types of mode waters in the range 16.2 ± 0.6°C, 35.6 ± 0.1 (Type I) and 12.9 ± 0.7°C, 35.2 ± 0.1 (Type II). The majority (67%) of the rings carrying mode waters had both types detected inside. Moreover, considering only those rings sampled west of the Mid-Atlantic Ridge, we found that 45% of them advected mode waters to the western basin. Therefore, our results demonstrate that, despite the long journey, interaction with the bottom topography and other vortices, ocean-atmosphere exchanges, and decay, the Agulhas rings are responsible for spreading mode waters initially available at the Cape Basin throughout the South Atlantic, contributing to a positive anomaly in temperature and salinity along the eddy corridor joining the Cape Basin to the Brazil Basin.

Abstract Coastal islands of Grande Rio, located south Rio de Janeiro and Maricá cities have been under multiple anthropogenic impacts. Despite these problems, these insular systems shelter a high diversity of fish species. Reef fishes are essential components of tropical marine coastal communities, also providing food and income for millions of people around the world. In this work, we generated an updated checklist from Cagarras Islands Natural Monument and surrounding areas based on fisheries data, literature records and multiple sampling techniques, including the Submersible Rotating Video technique, used for the first time in Brazil. We present an inventory of 282 fish species representing 91 different families, with 21 new records for the study area, including a non-native species (Heniochus acuminatus). In addition, our results show a moderate endemism level for the Brazilian province (approximately 6.0%), while 10.5% of species are assigned to one of IUCN’s threatened categories. Our efforts show the fish biodiversity scenario and their distribution on coastal islands more than 10 years after the Cagarras Islands Natural Monument establishment, reinforcing the importance of monitoring research programs for the management of this Marine Protected Area and surrounding waters, that play a key role for artisanal fisheries.

The article presents original data of chemical composition of tholeiitic basaltoids and andesites, dredged from the Shaka Ridge (South Atlantic) in the course of field research in spring 2016 on the scientific expedition vessel “Akademik Fedorov”. The analytical part of the work on estimating the contents of petrogenic, trace and rare-earth elements was carried out using the classical method (“wet chemistry”), X-ray fluorescence analysis (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). The studied samples demonstrate elevated concentrations of large-ion lithophile elements, or LILE, (Ba, Rb, Pb) and light rare earth elements, or LREE, (La, Ce, Nd, Sm) relative to high field strength elements, or HFSE, (Nb, Ta) and heavy rare earth elements, or HREE, (Dy, Yb, Lu). The specifics of trace element geochemistry suggest a significant contribution of crustal or subduction components to the magmas of the Shaka Ridge. Discrimination diagrams of basaltoids and allied rocks with fields of different geodynamic settings indicate that they were formed in the setting of the mid-ocean ridge basalt (MORB). The reason behind the appearance of subduction and crustal marks in the rocks is possibly associated with assimilation of crustal matter by magmas or lies in their inheritance from the mantle source.

The use of effect biomarkers has contributed to the understanding of the sublethal effects of contaminants on different organisms. However, the analysis of genotoxic markers as an indicator of organism and environmental health in sharks is underexplored. Thus, the present study investigated the relationship between the genomic damage frequency in erythrocytes and metal(loid) concentrations in whole blood of three shark species (Galeocerdo cuvier, Negaprion brevirostris and Ginglymostoma cirratum), taking into account climatic seasonality. The results showed that G. cuvier , an apex predator, presented the highest total erythrocyte genomic damage frequencies together with the highest mean whole blood concentrations of Al, Cd, Cr, Fe, Mn, Ni, Pb and Zn. The shark N. brevirostris also presented high levels of metal(loid), indicating a greater susceptibility to these contaminants in species that preferentially feed on fish. In contrast, G. cirratum , a mesopredator, presented the lowest erythrocyte damage frequencies and whole blood metal(loid) concentrations. The presence of micronuclei was the most responsive biomarker, and Al, As and Zn had an important effect on the genomic damage frequencies for all species evaluated. Zn concentration influenced the binucleated cells frequencies and Al concentration had an effect on the total damage and micronuclei frequencies in G. cuvier and N. brevirostris. Binucleated cells and blebbed nuclei frequencies were affected by As concentration, especially in G. cirratum , while showing a strong and positive correlation with most of the metals analyzed. Nonetheless, baseline levels of metal(loid) blood concentrations and erythrocyte genomic damage frequencies in sharks have not yet been established. Therefore, minimum risk levels of blood contaminants concentrations on the health of these animals have also not been determined. However, the high genomic instability observed in sharks is of concern considering the current health status of these animals, as well as the quality of the environment studied. [Display omitted] • The presence of micronuclei was the most responsive biomarker in sharks. • Al, As and Zn had an important effect on genomic damage frequencies in sharks. • Galeocerdo cuvier showed greater susceptibility to the metal(loid) analyzed. [ABSTRACT FROM AUTHOR]

• Sedimentological and structural characterization of the Ariri Formation in the Santos Basin. • Evidence for halokinetic deformations during salt deposition. • Influence of syn-salt deformation on evaporite depositional system. • Halokinesis during a salt giant deposition strongly influences later salt tectonics. Halokinetic deformations synchronous with salt deposition are processes already suggested in several salt giants including the Lower Cretaceous salt deposits of the Santos Basin in Brazil. However, the dynamics of syn-depositional deformation has never been studied in a coherent depositional and structural framework. This study investigates well data and high-resolution 3D seismic images in the evaporitic Ariri Formation of the Santos Basin to understand the intra-salt deformations, estimate their timing and establish a link with the depositional setting of the evaporites. The seismic data shows numerous examples of intra-salt onlaps, erosive surfaces and sedimentary wedges highlighting the occurrence of deformations during salt deposition. Two dominant processes have initiated salt creep: the density contrasts between a dense upper anhydrite-rich unit and a less dense lower halite-dominated unit and the gravitational system promoted by the late-rift subsidence. Updip, extension prevailed during salt deposition and favored a boudinage of the Ariri Formation. Downdip, early contraction favored the development of well-developed intra-salt minibasins. Deformation occurring during salt deposition and induced topographic relief likely influenced the hydrological conditions. It probably led to intra-salt dissolution/reprecipitation processes and hyper-saline conditions favoring the precipitation of tachyhydrite deposits in localized intra-salt depocenters. Eventually, post-salt minibasins systematically developed above syn-salt depocenters, indicating that syn-salt deposition deformation had a strong impact on post-salt evolution. This new understanding of the intra-salt deformation in the Santos Basin paves the way for new interpretations of halokinetic deformations reported elsewhere in the South Atlantic or in other salt-giant provinces. [ABSTRACT FROM AUTHOR]

Rocky shore communities are shaped by complex interactions among environmental drivers and a range of biological processes. Here, we investigated the importance of abiotic and biotic drivers on the population structure of key rocky intertidal species at 62 sites, spanning ∼50% of the Brazilian rocky shoreline (i.e., ∼500 km). Large-scale population patterns were generally explained by differences in ocean temperature and wave exposure. For the gastropod species Lottia subrugosa , differences at smaller scales (i.e., 0.1–1 km) were better explained by other abiotic influences such as freshwater discharge and substrate roughness. Based on the general population patterns of intertidal species identified, three main oceanographic groups were observed: a cold-oligotrophic grouping at northern sites (Lakes sub-region), a eutrophic group associated with large estuaries and urban zones (Santos and Guanabara bays); and a transitional warm-water group found between the two more productive areas. Larger individuals of Stramonita brasiliensis , L. subrugosa and Echinolittorina lineolata were generally found in the cold-oligotrophic system (i.e., upwelling region), while small suspension feeders dominate the warm-eutrophic systems. Evidence of bottom-up regulation was not observed, and top-down regulation effects were only observed between the whelk S. brasiliensis and its mussel prey Perna perna. Environmental drivers as compared to biotic interactions, therefore, play a key role determining the population structure of multiple intertidal species, across a range of spatial scales along the SW Atlantic shores. • Intertidal populations of key species are primarily influenced by seawater temperature. • Temperature and productive gradients determine three trophic oceanographic domains. • Large variability in species density and size was associated to within site differences. • The importance of estuaries on the dynamic of rocky shores is reinforced by their influence on observed patterns. [ABSTRACT FROM AUTHOR]

In 2020, the 250-person community of Tristan da Cunha announced the establishment of the fourth largest fully-protected MPA in the world: the Tristan da Cunha Marine Protection Zone (MPZ). The MPZ protects 91 % of the 750,000 km2 EEZ in the South Atlantic, which is home to numerous endemic and endangered species reliant on the healthy marine environment. After legal gazettement in 2021, the next challenge is to build strong foundations for the MPZ that will support it in perpetuity. The Tristan da Cunha community and its partners are rising to this challenge by developing and implementing a programme of work focused on three core areas for MPZ success: effective management, research and monitoring, and community stewardship. Alongside assistance in MPZ management from the UK Government Blue Belt Programme and the establishment of a conservation endowment fund, the RSPB, Blue Nature Alliance, and Tristan da Cunha Government are providing dedicated support for the community for the first years of the MPZ. The partnership is supporting the establishment of monitoring programmes and citizen science initiatives, providing mentorship opportunities, facilitating global knowledge exchanges, strengthening the community's cultural connection to its marine environment and enhancing the global identity of the Tristan da Cunha community as 'Atlantic Guardians'. Providing support for the MPZ that is adaptive, flexible and community led, beyond the moment of designation is essential for the longevity of the Tristan da Cunha Marine Protection Zone. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Copyright of Ler Historia is the property of Ler Historia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Conjuntura Austral is the property of Conjuntura Austral and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Recent oceanographic observations have identified significant changes of intermediate water masses characterized by increased temperatures, lowered pH and deoxygenation. In order to improve our understanding as to how these changes may impact deep-sea ecosystems one important strategy is to reconstruct past oceanic conditions. Here we examine the applicability of the scleractinian cold-water coral Solenosmilia variabilis as a marine archive for the reconstructions of past intermediate water mass temperatures by using Lithium (Li)/Magnesium (Mg) ratios. In particular, our study addresses 1) the calibration of Li/Mg ratios against in-situ temperature data, 2) the reconstruction of past intermediate water mass temperatures using scleractinian coral fossil samples from the Brazilian continental margin and 3) the identification of intraspecies variability within the coral microstructure. Results showed that Li/Mg ratios measured in the skeletons of S. variabilis fit into existing Li/Mg-T calibrations of other cold-water scleractinian. Furthermore, the coral microstructure exhibits interspecies variability of Li/Ca and Mg/Ca ratios were also similar to what has been observed in other cold-water scleractinian corals, suggesting a similar biomineralization control on the incorporation of Li and Mg into the skeleton. However, the Li/Mg based temperature reconstruction using fossil samples resulted in unexpectedly high variations >10°C, which might not be solely related to temperature variations of the intermediate water mass over the last 160 ka on the Brazilian continental margin. We speculate that such temperature variability may be caused by vertical movements of the aragonite saturation horizon and the associated seawater pH changes, which in turn influence the incorporation of Li and Mg into the coral skeleton. Based on these results it is recommended that future studies investigating past oceanic conditions need to consider the carbonate system parameters and how they might impact the mechanisms of Li and Mg being incorporated into skeletons of cold-water coral species such as S. variabilis.

Most marine plastic pollution originates on land. However, once plastic is at sea, it is difficult to determine its origin. Here we present a Bayesian inference framework to compute the probability that a piece of plastic found at sea came from a particular source. This framework combines information about plastic emitted by rivers with a Lagrangian simulation, and yields maps indicating the probability that a particle sampled somewhere in the ocean originates from a particular river source. We showcase the framework for floating river-sourced plastic released into the South Atlantic Ocean. We computed the probability as a function of the particle age at three locations, showing how probabilities vary according to the location and age. We computed the source probability of beached particles, showing that plastic found at a given latitude is most likely to come from the closest river source. This framework lays the basis for source attribution of marine plastic.

This study presents new quantitative data on benthic foraminifera from three bathymetric transects of the Brazil (11-14°S, 420-1900 m) and Campos (22°S, 430-2000 m) basins. The quantity and quality of organic matter flux as well as substrate properties and hydrodynamic conditions at the sediment-water interface are identified as key parameters controlling assemblage distribution. Based on the total (stained and unstained) fauna, a distinct biogeographic divide between a Globocassidulina subglobosa/crassa assemblage in the Campos Basin and a rosalinid/bolivinid assemblage in the Brazil Basin occurs across the bifurcation of the South Atlantic Central Water into its southward subtropical and northward tropical branches. In the Campos Basin, coarser sediments, increased bottom current activity, and variable nutrient supply favor an assemblage of Globocassidulina subglobosa/crassa, Nuttalides umbonifer and Alabaminella weddellensis. Occurrences of cold-water coral mounds in 870 m provide an ecological niche favoring species such as Alabaminella weddellensis which benefit from trapped nutrients. The Brazil Basin is characterized by increased abundances of Rosalina and Bolivina, while Globocassidulina subglobosa/crassa is comparatively less frequent. Assemblages with G. subglobosa/crassa, Rosalina spp., Bolivina variabilis and Bolivina subreticulata are favored by a relatively high nutrient input at 14°S. Further north, assemblages with Bolivina subreticulata, Bolivina variabilis, Epistominella exigua, G. subglobosa/crassa are located beneath the velocity core of the North Brazil Undercurrent (NBUC), coinciding with more clayey sediments rich in TOC. Occurrences of delicate branching forms such as Saccorhiza ramosa indicate a more stable setting, distal to the main current. Rose Bengal stained (living) specimens are scarce in all three regions, as is typical for deep-sea foraminiferal faunas. Their patterns of species distribution largely reflect those observed for the total fauna.