Southern Brazilian Continental Shelf Research Articles

Analysis of the Ocean–Atmosphere Interface in the Brazil Current Region

ABSTRACTThe Brazil current (BC) is a westerly current that flows south along the Brazilian coast, being part of the Southern Brazilian Continental Shelf (SBCS). Recent studies have indicated a trend towards intensification and a shift to the south of the region where this current predominates. We analysed the seasonality of the relationship between atmospheric variables and sea surface temperature (SST) with potential trends and changes in the spatio‐temporal pattern of these variables from 1980 to 2020 over the BCs area in the South Atlantic Ocean. For this purpose, monthly data on SST, air temperature at 2 m above the surface (T2M), mean sea level pressure (MSLP), zonal wind (U10) and meridional wind (V10), obtained from ERA5 reanalysis, were used. Descriptive statistical analyses, trends using the Mann‐Kendall test, correlation matrices and Pettitt's test revealed a significant spatial correlation between the variables, with temporal trends of variation, especially over the BCs area. The meridional (zonal) wind predominantly exhibited a north–south (west–east) direction, supporting the hypothesis that the study region was displaced. Additionally, statistically significant positive trends were observed for SST (0.02°C ∙ dec−1 in austral autumn, winter and spring and 0.01°C ∙ dec−1 in austral summer), T2M (0.02°C ∙ dec−1 in austral winter and spring), MSLP (0.05°C ∙ dec−1 in austral autumn) and negative for U10 (−0.01°C ∙ dec−1 in austral spring). Pettitt's test results confirm significant changes in the behaviour of most analysed variables from the late 1990s to the early 2000s. The post‐breakpoint periods of the variables consistently showed above‐average values compared to the pre‐breakpoint periods, supporting positive upward trends consistent with literature findings. In particular, they highlight the notable upward slope in SST in the BC region.

Under pressure: an integrated assessment of human activities and their potential impact on the ecosystem components of the Southern Brazilian continental shelf

Economic activities in the South Brazilian Shelf (SBS) are concentrated on the coast, causing several impacts. To balance biodiversity and habitat conservation in coastal and marine areas with human activities relevant to society, it is important to identify and understand those sectors and pressures. We conducted an analysis to assess ecosystem risks from multiple drivers and pressures in the continental shelf that extends from the Southernmost point of Brazil (Chuí) to Cabo Frio cape, in Rio de Janeiro State. We used the Integrated Ecosystem Assessment (IEA) methodology, a framework for implementing ecosystem-based management grounded on five steps: scoping, indicator development, ecosystem assessment, risk analysis, and management strategy evaluation. This work presents the scoping step consisting of a semi-quantitative assessment identifying sector–pressure–ecological component pressure pathways. Subsequently, these pathways were scored using expert judgment supported by literature and data, regarding their level of overlap with each ecosystem component, frequency of occurrence, and degree of impact, enabling estimation of the magnitude of impact risk arising from each one of the sectors and pressures. The assessment involved 20 experts from multiple disciplines and backgrounds. To validate the results, we conducted a thorough literature review and engaged in further discussions with relevant stakeholders. As a result, 16 sectors and 19 pressures were identified as impacting 18 ecological components. Fishing, land-based industry, tourism and recreation, wastewater, and coastal infrastructure represented the main economic sectors impacting the area. The major associated pressures were the incidental catch of species, the introduction of contaminants and organic matter into the water, and the generation of waste. The most affected ecosystem components were, in turn, those located on or close to the coast, such as mangroves, saltmarshes, and rocky reefs while the preeminent impacted taxonomic groups were elasmobranchs, seabirds, reptiles, mammals, and bony fish. The literature review supported the expert assessment, and the stakeholders’ workshop endorsed our findings. Additionally, this assessment highlights the need to implement public policies that focus on reducing the impact of the most influential sectors and pressures and the necessity of strengthening research and monitoring. Identifying these priorities for integrated coastal and marine management is crucial, and our research outcomes can be key in promoting regional ocean sustainability.

Analysis of a coastal-trapped wave generated by the 2016 extra-tropical cyclonic system in the Southern Brazilian continental shelf with COAWST modeling system

This study used the coupled ocean-atmosphere regional model (COAWST) to evaluate the effect of the trapped wave formed by a frontal system over the Southern Brazilian Continental Shelf (SBCS) during September 2016. The oceanic model was configured for the domain of 20–40°S/40–60°W, with a horizontal resolution of 1/9°, 32 vertical levels, and forced with Global Ocean Sea Physical Analysis and Forecasting Products. The model simulations were compared to remote sensing and tide gauges data, with a correlation higher than 0.78 between the wind and sea level rise data and higher than 0.82 for the wave amplitude and phase. Our results showed the presence of a sea level anomaly propagating northward along the continental shelf at 480 km.day−1, probably associated with the presence of a coastal-trapped wave. The analyzed period consisted of the rapid formation of an extra-tropical cyclone on the model grid, intensifying the south-quadrant winds and the associated Ekman transport. The zonal acceleration and Coriolis terms were strongly associated with the wave crossing, with an amplitude greater than 2.10−5 m.s−2. The Coriolis term follows the geostrophic flow induced by the wave crest, with values greater than 4.2 m.s−2, and a correlation coefficient of 0.82 with the pressure gradient and friction terms. The trapped wave reversed the pressure gradient and the over-shelf flow with a negative geostrophic flow (average westward shelf flow). Our results reinforce the fact that these processes change the physical and chemical seawater properties over the SBCS, changing the mixing layer and fertilizing its shelf waters.

Historical deposition of PAHs in mud depocenters from the Southwestern Atlantic continental shelf: The influence of socio-economic development and coal consumption in the last century

Polycyclic aromatic hydrocarbon (PAH) concentrations were determined in four dated sediment cores collected in mud depocenters of the southern Brazilian continental shelf. Core dating results covered the interval between 1925 and 2017. The total PAH concentrations (ΣPAHs) ranged from 44.69 ng g−1 to 305.43 ng g−1 and were similar between the analysed cores. Fine-grained sediments and total organic carbon (TOC) results did not correlate with the ΣPAHs, indicating that the variations in PAH concentrations are mostly related to variations in sources and emissions. PAH source appointment indicated a high input of a natural compound (perylene) and the predominance of anthropogenic PAHs from coal, biomass, and fuel combustion. Alkylated PAHs presented high contributions throughout all cores. The historical deposition of PAHs was associated with different periods of the socio-economic and industrial development of near coastal cities and reflected very well the history of coal production and consumption in the southern region of Brazil. The low levels of ΣPAHs before 1945 in all analysed cores may be related to the beginning of the industrialization process and the lower urbanization degree in the region. Between 1945 and 1965, the gradual ΣPAHs increase reflects the establishment and enlargement of the southern Brazilian industrial sector. The interval between 1965 and 1990 corresponded to the highest ΣPAHs in three of the four analysed cores. After 1990, a relative decrease in the ΣPAHs was observed in most cores and may be related the multiple cuts of incentives to the industrial usage of coal, as well as to Brazil's efforts in environmental regulation for coal extraction and consumption.

Observations of air–sea heat fluxes in the southwestern Atlantic under high‐frequency ocean and atmospheric perturbations

AbstractTurbulent air–sea heat fluxes were computed from in situ high‐frequency micrometeorological data during two research cruises performed in the southwestern Atlantic Ocean (SWAO) occurring in June 2012 and October 2014. Two different and dynamical areas were covered by the cruises: the Brazil‐Malvinas Confluence (BMC) and the Southern Brazilian Continental Shelf (SBCS). The eddy covariance (EC) method was used to estimate the air–sea sensible‐ and latent‐heat fluxes. This article compares these novel high‐frequency estimates of heat fluxes with bulk parametrizations made at the same location and time from independent measurements taken on board the ships. When comparing the EC and bulk‐estimated time series of sensible‐heat fluxes, we found a good agreement both in their magnitude and variability, with small bias (generally <20 W·m−2) between the datasets from the two study areas in the SWAO. However, the EC and bulk latent‐heat flux comparisons show large biases ranging from 75 W·m−2 to 100 W·m−2 in the SBCS and BMC, respectively. These biases were always associated with short‐term, high‐frequency environmental perturbations occurring either in the atmosphere or in the ocean with the majority related to strong wind burst events and large air–sea temperature gradients. The short period changes in atmospheric conditions were mostly related to the passage of transient synoptic systems over the two study areas. The large air–sea temperature gradients were mostly linked to the surface characteristics of the BMC and SBCS regions, where sharp oceanographic fronts are located. Our results are able to contribute to improving weather and climate simulations of the mid‐ to high latitudes of South America, a region largely influenced by the sea‐surface temperature patterns of the SWAO in combination with the frequent propagation of transient atmospheric systems.

Phyto- and protozooplankton assemblages and hydrographic variability during an early winter survey in the Southern Brazilian Continental Shelf

Abstract The distribution of phytoplankton and protozooplankton assemblages in relation to hydrographic variability across the southern Brazilian continental shelf were studied based on data collected during early winter (June/2012), complemented with MODIS-Aqua satellite imagery. The in situ data set was comprised by water column structure properties, dissolved inorganic nutrients (ammonium, nitrite, nitrate, phosphate and silicate), phytoplankton and protozooplankton composition and biomass [chlorophyll a (Chl a) concentration and carbon content]. Phytoplankton assemblages were assessed by both microscopy and HPLC-CHEMTAX approaches. A canonical correspondence analysis associating physical, chemical and phytoplankton composition data at surface revealed a tight coupling between the phytoplankton community and hydrographic conditions, with strong environmental gradients across three different domains: the pelagic, outer shelf Tropical Water (TW); the mid shelf domain under influence of Subtropical Shelf Water (STSW); and the inner shelf domain, mainly under influence of riverine outflow of the La Plata River Plume Water (PPW). Results showed that diatoms dominated the phytoplankton assemblages throughout the study region, but other groups were also important and varied according to the different water masses at surface. The low salinity and nutrient-rich PPW stimulated a high phytoplankton biomass and diversity of diatoms and dinoflagellates within the inner shelf region, with enhanced Chl a levels (>1.3 mg m−3) and a great abundance of large and medium-sized diatoms (some of these appeared exclusively in PPW), as well as ciliates, dinoflagellates, raphidophyceans and cryptophytes. Conversely, smaller diatoms (e.g. Rhizosolenia clevei), picoplanktonic species (prochlorophytes and cyanobacteria) and a noticeable contribution of dinoflagellates and other flagellates, associated with lower Chl a levels (

FORECAST STRUCTURE DEVELOPMENT FOR MODELLING THE SOUTHERN BRAZILIAN CONTINENTAL SHELF HYDRODYNAMIC

Global forecast models have been widely used worldwide; however, they lack ability to prescribe high quality local data. In this paper, an assembly of oceanographic (RTOFS) and atmospheric (GFS) global data base are used to set up a nested forecast system. The approach proposed relies on the sage of python and FORTRAN scripts to download and assemble global metocean data, in addition to interpolate it towards the study area numerical grid as boundary conditions. Therefore, the TELEMAC-3D hydrodynamic model is automatically initiated in order to provide the regional forecast for the Southern Brazilian Continental Shelf. Results shows that the methodology proposed represent properly the flow dynamics inside the Patos Lagoon and also in the Tramandaí beach, with low/high frequency dynamic effects and influences being reported.

Surficial sediments of the Paraná Inner Continental Shelf, Southern Brazil

This study examines surficial sediment distribution patterns, slope and morphological characteristics of the Parana inner continental shelf. Parana inner continental shelf is located on the southern Brazilian continental shelf, a wide and low gradient shelf, in the vicinity of two large unfilled estuaries and the Serra do Mar mountain range. It is characterized as a wave/storm dominated continental shelf with microtidal, semidiurnal regime and a small supply of recent continental sediments. We analyzed grain-size parameters and sediment composition of 875 grab samples and investigated the inner continental shelf morphology and slope through a digital bathymetric model built from regional nautical charts. We combined and evaluated the characteristics of grain-size curves, the spatial distribution of sediments, and the morphology and slope of the inner continental shelf to identify different sedimentary facies. Sediment distribution patterns change from the coast seaward and between three defined sectors along the coastline: south, central and north inner continental shelf. This variation seems to be related to recent sediment sources and to the presence of deposits from ancient coastal plain and inner continental shelf environments formed before the last Holocene sea-level highstand. Sediments with mean diameter of fine to very fine sands prevail at all depths. Deposits of sediments with mean diameter of silt and medium to coarse sands are significant in particular areas, generally associated with steep slopes, troughs, and sand ridges. Possible causes of sedimentary patchiness are the outcropping of medium to coarse sand and the supply of recent estuarine muddy sediments provided by large estuarine complexes to the Parana inner continental shelf. The results obtained contribute to the knowledge about the sediment dynamics of Parana inner continental shelf.

Regional modeling of the water masses and circulation annual variability at the Southern Brazilian Continental Shelf

The Southern Brazilian Continental Shelf (SBCS) is one of the more productive areas for fisheries in Brazilian waters. The water masses and the dynamical processes of the region present a very seasonal behavior that imprint strong effects in the ecosystem and the weather of the area and its vicinity. This paper makes use of the Regional Ocean Modeling System (ROMS) for studying the water mass distribution and circulation variability in the SBCS during the year of 2012. Model outputs were compared to in situ, historical observations and to satellite data. The model was able to reproduce the main thermohaline characteristics of the waters dominating the SBCS and the adjacent region. The mixing between the Subantarctic Shelf Water and the Subtropical Shelf Water, known as the Subtropical Shelf Front (STSF), presented a clear seasonal change in volume. As a consequence of the mixing and of the seasonal oscillation of the STSF position, the stability of the water column inside the SBCS also changes seasonally. Current velocities and associated transports estimated for the Brazil Current (BC) and for the Brazilian Coastal Current (BCC) agree with previous measurements and estimates, stressing the fact that the opposite flow of the BCC occurring during winter in the study region is about 2 orders of magnitude smaller than that of the BC. Seasonal maps of simulated Mean Kinetic Energy and Eddy Kinetic Energy demonstrate the known behavior of the BC and stressed the importance of the mean coastal flow off Argentina throughout the year.

Uma Revisão dos Processos de Interação Oceano-Atmosfera em Regiões de Intenso Gradiente Termal do Oceano Atlântico Sul Baseada em Dados Observacionais

Resumo De um modo geral, a interação do oceano com a atmosfera em regiões de intensa atividade da mesoescala oceânica (frentes oceanográficas, meandros e turbilhões de escalas espaciais típicas de cerca de 100-500 km e escalas temporais de cerca de 2-3 meses) apresenta uma correlação positiva entre a temperatura da superfície do mar (TSM) e variáveis meteorológicas tais como a estabilidade da Camada Limite Atmosférica Marinha (CLAM), a intensidade do vento e os fluxos de calor, de momentum e de gases entre o oceano e a atmosfera. Isto sugere que o oceano força a atmosfera nas escalas espaciais e temporais relacionados à mesoescala oceânica. Principalmente com base em dados observacionais, porém não exclusivamente, este trabalho apresenta uma breve revisão científica sobre o impacto das estruturas de mesoescala presentes no Oceano Atlântico Sudoeste em alguns componentes do sistema acoplado oceano-atmosfera que, em certos aspectos, impactam o tempo e o clima da regiões continentais adjacentes na América do Sul. Inclui-se neste artigo também uma breve revisão do estado da arte do conhecimento sobre a parte oceânica da Zona de Convergência do Atlântico Sul. Este artigo apresenta as características oceanográficas gerais da área de estudo, incluindo alguns aspectos sobre a circulação do Atlântico Sul e a variabilidade. Lembrando do fato que o Atlântico Sudoeste e Sul são regiões consideradas como trilha de tempestade, este trabalho também discute os impactos dos gradientes de TSM do Oceano Atlântico Sul Ocidental sobre os sistemas atmosféricos transientes que atravessam frequentemente esta região. Além disso, o artigo discute novos indícios de que os processos oceanográficos que ocorrem no litoral sul do Brasil no inverno tem um forte impacto sobre a modulação CLAM sobre a plataforma continental do sul do Brasil. O artigo aponta também índicos passados e presentes que os processos ecológicos causados pela variabilidade climática atmosférica e marinha na costa sul do Brasil impactam na desova e captura da sardinha (Sardinella Brasiliensis), que é um dos mais importantes recursos marinhos renováveis do Brasil. O artigo termina apresentando alguns dos esforços observacionais atuais do Brasil, visando a coleta de dados meteorológicos e marinhos no Oceano Atlântico Equatorial e Sul. Estes esforços visam aumentar a nossa compreensão do acoplamento oceano-atmosfera nas escalas sinóticas e climáticas, bem como o papel do Oceano Atlântico em controlar o calor, momentum e fluxos de dióxido de carbono para a atmosfera.

Air‐sea interaction at the Southern Brazilian Continental Shelf: In situ observations

AbstractThe influence of the cross‐shelf oceanographic front occurring between the Brazil Current (BC) and the Brazilian Coastal Current (BCC) on the local Marine Atmospheric Boundary Layer (MABL) is investigated here. This front is typical of wintertime in the Southern Brazilian Continental Shelf (SBCS) and this is the first time that its effects are investigated over the above MABL. Here we analyze variability, vertical structure, and stability of MABL as well as heat fluxes at air‐sea interface, across five oceanographic transects in the SBCS made during a winter 2012 cruise. Local thermal gradients associated with mixing between distinct water masses, play an essential role on MABL modulation and stability. Although weaker when compared with other frontal regions, the cross‐shelf thermal gradients reproduce exactly what is expected for open ocean regions: Stronger (weaker) winds, lower (higher) sea level pressure, and a more unstable (stable) MABL are found over the warm (cold) side of the oceanographic front between the BC (warm) and coastal (cold) waters. Our findings strongly support the coexistence of both known MABL modulation mechanisms: the static and hydrostatic MABL stability. This is the first time that these modulation mechanisms are documented for this region. Turbulent fluxes were found to be markedly dependent on the cross‐shelf SST gradients resulting in differences of up to 100 W.m−2 especially in the southernmost region where the gradients were more intense.

MANIFESTO OF THE SOUTH AMERICAN SCHOOL OF (ACTUALISTIC) TAPHONOMY

When the young Charles Darwin explored the Atlantic coast of southern South America, he was impressed by its fossils—as he wrote in the first paragraph of the Origin of Species (1859)—and the magnitude of its “wide and desolate” plains (Darwin 1839, p. 124). Although his adventures on the Patagonian plains became more famous, Darwin’s first observations were on the Pampas, a flat area that covers parts of Argentina, Brazil and Uruguay, where the gaucho was lord and master. Since that time, these flat lowlands have been the object of much geological and paleontological research, but there is still much more to discover, especially in the field of taphonomy. South America is particularly suited to test taphonomic ideas thanks to the recent geological evolution of the area, associated with sea level oscillations since the Pleistocene, which left numerous lagoons and estuaries along the coast. In fact, the Patos Lagoon (Brazil) and Rio de La Plata (Uruguay and Argentina) are the largest lagoon and one of the largest estuaries in the world, respectively, providing vast areas of diverse shallow coastal environments. In the terrestrial realm, southern Argentina is characterized by fluvial systems originating in the high Andes Cordillera as well as numerous permanent and temporary lakes due to the gentle slope of the plain. In addition to a diverse array of marine and terrestrial environments, exposures of fossiliferous accumulations from continental shelf, coastal plain, and freshwater basin settings provide exceptional opportunities for comparing modern death assemblages with fossil counterparts. Thanks in part to this profusion of “natural taphonomy laboratories”, actualistic taphonomy in South America is experiencing a period of exciting growth and advancement. Studies on the southern Brazilian continental shelf have focused on the comparative taphonomy of bivalved mollusks and brachiopods (Kowalewski et al. 2002; Carrol et al. 2003; Rodland et al. 2004 …

The Subfamily Cytheropterinae Hanai, 1957 (Subphylum Crustacea, Class Ostracoda) from the Southern Brazilian Continental Shelf

The study of the subfamily Cytheropterinae from the southern Brazilian continental shelf reveals the presence of four genera and nine species, including two newly described (Cytheropteron sudatlanticum sp. nov., Loxoreticulatum pulchrum sp. nov.) and two left in open nomenclature (Cytheropteron sp. and Kangarina sp.). All of these species are restricted to the southern part of the Southwest Atlantic Ocean and do not extend beyond the coast of Rio de Janeiro, Brazil. Three of these species (Oculocytheropteron micropunctatum, O. reticulatum, O. macropunctatum) extend beyond the southern limit of the Brazilian Province (36°S), while the others occur inside the limits of the Brazilian Province (36°S–22/21°S). The genus Loxoreticulatum, a well-known ostracod taxon from the Antarctic Peninsula, southern Argentina and Falkland (=Malvinas) Islands, is herein reported for the first time from offshore Brazil.

Controls on water column chemistry of the southern Brazilian continental shelf

Chemistry of Southern Brazilian Continental Shelf (SBS) waters, between 28.5°S and 34°S, is evaluated in relation to the mixing of thermohaline defined water masses and concomitant water column processes. Data on inorganic nutrient and trace metal (Ba, Cd, Co, Cu, Fe, Mn, U, V and Zn) concentrations and radium isotopic activities from previous reports and recent analyses are presented and discussed with the aim of providing a state of knowledge on processes governing their sources, distribution, transport and fate on the SBS.Nutrients concentrations/distributions on the shelf are controlled mainly by Tropical Water/Subtropical Shelf Water, seasonally modified as a result of summer upwelling in the northern shelf region, and by Plata Plume Water, which is seasonally modified by discharges of submarine groundwater (SGD), the Patos Lagoon and by the greater northern penetration of the Rio de la Plata plume during winter. Radium-226 activity varies little across the shelf. Radium-228 activity, associated dominantly with SGD, decreases conservatively, with respect to salinity, across shelf transects, converging on a typical ocean endmember activity. The low salinity endmember activity, however, depends on the location of the shelf transect controlled by the variability of coastal SGD. Because SGD is so important to the coastal shelf region, 228Ra activity appears to provide a better tracer of water mass interactions than thermohaline characteristics. Using metal–228Ra relationships, sources, transport and fate of trace metals are better constrained enabling the following conclusion: The major source of dissolved Co, Mn and Fe to the shelf is SGD, along the coastal Holocene barrier system, followed by removal as coastal water mixes across the shelf. Cu and Si concentrations are explained as conservative mixtures of three endmembers: SGD, surface freshwater discharge and oceanic. Cd and Zn are largely explained similarly. Vanadium is enriched in coastal waters during the summer presumably due to seasonal remobilization from sediments but exhibits conservative mixing behavior across the shelf. Barium behavior is the most unexpected and is speculated to be the result of biochemical removal in highly productive coastal waters followed by release from decaying phytoplankton detritus as it is advected across the shelf.

Submarine groundwater discharge revealed by radium isotopes (Ra-223 and Ra-224) near a paleochannel on the Southern Brazilian continental shelf

Submarine Groundwater Discharge (SGD) has been recognized as an important component of the ocean-continent interface. The few previous studies in Brazil have focused on nearshore areas. This paper explores SGD on the Southern Brazilian Continental Shelf using multiple lines of evidence that include radium isotopes, dissolved nutrients, and water mass observations. The results indicated that SGD may be occurring on the Continental Shelf in the Albardão region, near a paleochannel located 50 km offshore. This paleochannel may thus be a preferential pathway for the delivery of nutrient- and metal-enriched groundwater and porewater into continental shelf waters.

Remarks on the morphology and distribution of some rare centric diatoms in southern Brazilian continental shelf and slope waters

This paper provides information on the morphology and occurrence of extant diatoms of the family Asterolampraceae and Azpeitia species of the southernmost Brazilian continental shelf and slope waters in the Southwestern Atlantic Ocean (28 -34ºS), under the influence of Tropical, Subtropical, Subantarctic Waters, terrestrial discharges from La Plata River and Lagoa dos Patos lagoon. Plankton was sampled (20 µm net; vertical hauls) at the same 27 stations in winter 2005 and summer 2007. Among Asterolampraceae, Asteromphalus flabellatus was the most frequent species (57% of samples) observed mainly in winter samples (92%) in Subtropical Shelf Water but also under the influence of La Plata River plume (salinity <35). Lower frequencies were observed for Asterolampra marylandica, Asteromphalus elegans, Asteromphalus heptactis and Spatangidium arachne. Four species of Azpeitia were observed: A. barronii and A. neocrenulata for the first time in the South Atlantic Ocean while A. africana and A. nodulifer had already been registered in equatorial and southern areas of Brazil. All Azpeitia species were rare (19%) in offshore samples (100-200 m depth. Remarks on the morphology based on light and scanning electron microcopy observations are provided along with their distribution in the study area.

Representativity of Quaternary mammals from the Southern Brazilian continental shelf

Representativity of Quaternary mammals from the Southern Brazilian continental shelf

Recent Ostracods (Family Trachyleberididae) from the Southern Brazilian Continental Shelf

The present study is a further contribution to the systematic knowledge of the ostracods from the southern Brazilian continental shelf. Twelve species of Trachyleberididae are recorded, including the following six new taxa: Cativella ornelasae sp. nov., C. sudbrasilienis sp. nov. sp., Henryhowella inflata sp. nov., Henryhowella verrucosa sp. nov., Ambocythere venusta sp. nov. and Basslerites costata sp. nov. The other six species have been recorded in previous studies, either in shallow or bathyal depths in both Brazilian waters and adjacent areas. Most species recorded herein are distributed in the neritic zone, except three, i.e., Trachyleberis aorata, Ambocythere venusta sp. nov. and C. sudbrasilienis sp. nov. The first two species are eurybathic, while C. sudbrasilienis sp. nov. is restricted to the inner shelf.

Pleistocene mammals from the southern Brazilian continental shelf

Abstract Fossils of terrestrial mammals preserved in submarine environment have been recorded in several places around the world. In Brazil such fossils are rather abundant in the southernmost portion of the coast, associated to fossiliferous concentrations at depths up to 10 m. Here is presented a review of such occurrences and the first record of fossils in deeper areas of the continental shelf. The fossils encompass several groups of both extinct and extant mammals, and exhibit several distinct taphonomic features, related to the marine environment. Those from the inner continental shelf are removed and transported from the submarine deposits to the coast during storm events, thus forming large konzentrat-lagerstatte on the beach, called “Concheiros”. The only fossils from deeper zones of the shelf known so far are a portion of a skull, a left humerus and of a femur of Toxodon sp. and a lower right molar of a Stegomastodon waringi , all collected by fishermen at depths around 20 m. The presence of fossils at great depths and distances from the present coastline, without signs of abrasion and far from areas of fluvial discharges does indicate that these remains have not been transported from the continent to the shelf, but have been preserved directly on the area that today correspond to the continental shelf. These remains indicate the existence of large fossiliferous deposits that have developed during periods of sea-level lowstand (glacial maxima) and have been submerged and reworked by the sea-level rise at the end of the last glaciation.

The Staircase Structure of the Southern Brazilian Continental Shelf

We show some evidences that the Southeastern Brazilian Continental Shelf (SBCS) has a devil′s staircase structure, with a sequence of scarps and terraces with widths that obey fractal formation rules. Since the formation of these features is linked with the sea‐level variations, we say that the sea level changes in an organized pulsating way. Although the proposed approach was applied in a particular region of the Earth, it is suitable to be applied in an integrated way to other shelves around the world, since the analyses favor the revelation of the global sea‐level variations.