Dinâmica espaço-temporal da pesca industrial de camarão-rosa Farfantepenaeus subtilis na plataforma continental do Amazonas

O conhecimento da distribuição espacial dos recursos pesqueiros e um fator essencial no ordenamento pesqueiro. O camarão-rosa Farfantepenaeus subtilis (Perez-Farfante, 1967) e uma espécie de importância econômica, capturado pela pesca industrial na Plataforma Continental do Amazonas. Este estudo teve como objetivo avaliar padrões espaços-temporais da abundancia relativa desse recurso a partir de uma serie de capturas realizadas por barcos da frota industrial, especializadas com o uso de ferramentas de sistema de informações geográficas. A abundancia relativa de camarão-rosa (CPUE) foi relacionada a batimetria, as características do substrato, a vazão do rio Amazonas e as variáveis oceanográficas obtidas por sensoriamento: temperatura da superfície do mar e concentração de clorofila-a. Entre as categorias de tipo de substrato, observou-se maior intensidade de arrastos na região de lama mosqueada. Nessa região, características como tipo de substrato (lama), relevo submarino, taxa de sedimentação (<1 cm.ano-1), e salinidade (>30) constituem o habitat ideal para o camarão-rosa. Maiores valores de CPUE estiveram associados a menores temperaturas e a maiores valores de concentração de clorofila-a, características que ocorrem no período de maior vazão do rio Amazonas, no primeiro semestre. Foi observada a ocorrência de três períodos com diferentes níveis de produção: fevereiro a abril (maior vazão), com maior abundancia relativa de camarão-rosa; maio a julho; e agosto a setembro (menor vazão), com menor abundancia. Os resultados mostraram que a abundancia relativa de F. subtilis não se distribui de modo uniforme no espaço nem na variação sazonal.

Dinâmica populacional das raias-violas, Rhinobatos horkelli, Rhinobatidae percellens e Zapteryx brerostris (Chondrichthyes, Rhinobatidae) da plataforma continental de São Paulo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Caracterização de sedimentos do testemunho NAP61-1 da plataforma continental da bacia de Santos por meio de susceptibilidade magnética

A parameter commonly used in investigations of environmental magnetism is the magnetic susceptibility (MS), which is the quantitative measure of the ability of magnetization of a specific material in the presence of an induced magnetic field. The present study aimed to determine the magnetic susceptibility of sediments collected on the continental shelf near the Santos Basin, southeast of the São Sebastião island (25°57.97’S 45°07.81'W), seeking to identify the possible source area of terrigenous sediments and the flow patterns of siliciclastic sediment yield in the area. It was used particle size analysis and contents of organic matter and calcium carbonate to characterize the sediments, besides paleomagnetism parameters. The analyzed material - core NAP61-1 - was collected using the piston corer sampler in 60 meters water depth, recovering 3.98 meters of sediment core. As from experiments, cyclicity was observed in relative abundance between sand and silt, most likely due to rapid and cyclical variations in the depositional environment. In general, the MS values are low, and show that the sand supply (terrigenous material) has a certain consistency, probably having the same origin. More absolute age is still necessary to establish clearly the events marked here

Estudo das diferentes formas de fósforo nas águas da plataforma continental do Amazonas

Hydrological samples were collected on the continental shelf of the Amazon river to determine particulate organic and inorganic matter, dissolved organic phosphorus (DOP), phosphate, total particulate phosphorus (TPP), chlorophyll a, temperature, salinity, pH, water transparency, dissolved oxygen (DO) and saturation rate. The objective was to study the forms of DOP, phosphate and TPP. In the euphotic layer, the fluvial discharge from the Amazon river favored the distribution of phosphate, TPP and DOP. In the aphotic layer, the phosphate concentration increased due to the decomposition of DOP and TPP. This increase is due to the absence of photosynthetic processes.

Variação espacial e temporal da trama trófica bentônica de um ambiente costeiro à plataforma continental adjacente no Atlântico Sudoeste: análise de isótopos estáveis

A análise das razões de isótopos estáveis de carbono (δ13C) e nitrogênio (δ15N) vem sendo utilizada para identificar as fontes primárias de carbono dos ecossistemas e traçar as interações tróficas entre seus componentes. Nesse contexto, a variabilidade espacial e temporal da trama trófica bentônica da Baía de Santos e da plataforma continental interna e média, ao largo da costa sul do estado de São Paulo, Brasil (23,9-24,5°S), foi investigada durante o inverno de 2005 e o verão de 2006. A matéria orgânica particulada em suspensão (MOPS), zooplâncton, macroalgas, vegetais terrestres (C3), sedimento e 21 categorias de consumidores bentônicos foram analisados. Segundo os valores de δ13C, a MOPS foi a principal fonte primária de matéria orgânica. A análise de regressão entre os valores médios de δ15N e δ13C indicou, no inverno, semelhanças nas assinaturas isotópicas dos consumidores bentônicos entre a plataforma interna e média e diferenças entre essas e as da baía. Por outro lado, no verão, foram observadas diferenças nessas assinaturas entre a baía, a plataforma interna e a média. Os valores de 13C dos consumidores decresceram do ambiente costeiro em direção à plataforma média, enquanto os de 15N aumentaram. Em relação ao δ13C, houve diferença da MOPS, possivelmente pela contribuição de produção primária nova (PPN) ou do microfitobentos no verão. Quanto ao δ15N, o enriquecimento da mesma categoria trófica no gradiente ambiental pode ser devido às diferenças na MOPS, resultante da PPN na plataforma interna no verão, decorrente da entrada da Água Central do Atlântico Sul (ACAS), que enriquece a água oligotrófica nessa área

Levantamento dos níveis de metais e compostos orgânicos em sedimentos superficiais da plataforma continental adjacente à Baía de Santos (Brasil)

O estuário Santista (SP) é uma das áreas mais impactadas do litoral paulista. A industrialização e a urbanização ocorridas no litoral central do estado de São Paulo, ao longo dos últimos 70 anos, acarretou significativas mudanças na dinâmica sedimentar do estuário e da baía de Santos, sem que se conheça o real impacto destas modificações na sequência sedimentar depositada na plataforma continental interna adjacente.

Do direito do mar e de seus avatares : a plataforma continental brasileira

Inclui bibliografia.

Registro del evento 8.2 ka en la plataforma continental de Alicante (SE, España)

High resolution seismic profiles of the Alicante continental shelf have been studied identifying a seismic prism which top at about -20 m below today sea-level. The prism is covered by recent sediments and can be interpreted as formed during a short interval of stand-by in the general transgression after the last glacial maximum. The -20 m level have been compared with the holocene Mediterranean sea-level-curve to propose an age of about 8 ka BP coinciding with the «8.2 ka cooling event» that was an abrupt, widespread climate instability. The prism top is deeper in the northern seismic profiles thus indicating a more subsidence that the southern coastal shelf where an erosion surface with rocky shoals configure the sea bottom.

El prisma sedimentario submarino ligado al Younger Dryas en la plataforma continental de Benidorm (Alicante, SE de España)

Con el objetivo de ampliar los conocimientos en relación a los cambios recientes del nivel en la plataforma continental de Alicante se ha procedido al estudio de diferentes perfiles sísmicos de alta resolución. En el presente trabajo se ha identificado un prisma sedimentario cuyo techo se ubica alrededor de los 60 metros por debajo del nivel del mar actual. Comparando los resultados con la curva de variaciones del nivel del mar de los últimos 20 milenios, se puede confirmar que éste se formó durante un periodo en que el nivel del mar permaneció relativamente constante o disminuyó levemente entre el final del Bølling Warming y tras el evento frío Younger Dryas. Un total de tres unidades sísmicas (1, 2 y 3 de base a techo) se pueden diferenciar en el prisma. La subunidad 1, depositada entre el final del Bølling Warming y antes del Younger Dryas, indicando una mayor ralentización de la tasa de ascenso del nivel del mar. La subunidad 2, formada durante el evento frío Younger Dryas, reflejando un episodio de detención del nivel del mar alrededor de los 60 metros, seguido de una caída relativa mismo. La subunidad 3, formada tras este periodo frío y que se caracteriza por un incremento de la tasa de ascenso del nivel del mar.

Asentamiento y reclutamiento de poliquetos bentónicos en la plataforma continental frente a Callao desde verano a invierno de 2015

La diversidad en los estadios de desarrollo de los poliquetos bentónicos fue estudiada en un perfil batimétrico de la plataforma continental central frente a Callao (Perú, 12°S) del verano al invierno del 2015, con el objetivo de determinar el asentamiento de larvas y reclutamiento de poliquetos bentónicos, bajo la influencia de los factores abióticos del agua y sedimento: temperatura, salinidad, oxígeno disuelto de fondo, sulfuro de hidrógeno en agua intersticial, fitopigmentos totales, materia orgánica total y biopolímeros lábiles. Se encontró un total de 25 especies, pertenecientes a 15 familias. La familia Spionidae presentó la mayor diversidad de larvas (06 especies), seguida de la familia Pilargidae (03 especies). Las larvas de Magelonidae fueron dominantes en verano y otoño. La disponibilidad larval en la capa de fondo estuvo asociada al régimen de oxigenación en el gradiente batimétrico. El número de larvas de poliquetos disminuyó desde el ambiente somero hacia la plataforma externa. Asimismo, la abundancia total de larvas de poliquetos y la abundancia de larvas de Magelona phyllisae se redujeron con el aumento de la temperatura y de la profundidad de la oxiclina durante el período de estudio, caracterizado por la influencia del evento El Niño 2015 - 2016. Por otro lado, se encontró que el número de especies de poliquetos juveniles y adultos fue mayor en ambientes someros, con mayor grado de oxigenación pero también condiciones más reductoras en el sedimento. No obstante, el éxito del reclutamiento, inferido a partir de la abundancia de individuos adultos y la proporción entre el número de especies en estadio adulto y el estadio juvenil fueron mayores en la plataforma externa deficiente en oxígeno, lo cual fue explicado principalmente por la contribución de Paraprionospio pinnata, especie dominante y típica de sedimentos de la plataforma continental.

Análise geoambiental da plataforma continental Rasa Equatorial, por meio de sensoriamento remoto e dados sedimentológicos: parrachos de Rio do Fogo-RN, Brasil

In the shallow continental shelf in Northeastern Rio Grande do Norte - Brazil, important underwater geomorphological features can be found 6km from the coastline. They are coral reefs, locally known as “parrachos”. The present study aims to characterize and analyze the geomorphological feature as well as the ones of the benthic surface, and the distribution of biogenic sediments found in parrachos at Rio do Fogo and associated shallow platforms, by using remote sensing products and in situ data collections. This was made possible due to sedimentological, bathymetric and geomorphological maps elaborated from composite bands of images from the satellite sensors ETM+/Landsat-7, OLI/Landsat-8, MS/GeoEye and PAN/WordView-1, and analysis of bottom sediments samples. These maps were analyzed, integrally interpreted and validated in fieldwork, thus permitting the generation of a new geomorphological zoning of the shallow shelf in study and a geoenvironmental map of the Parrachos in Rio do Fogo. The images used were subject to Digital Image Processing techniques. All obtained data and information were stored in a Geographic Information System (GIS) and can become available to the scientific community. This shallow platform has a carbonate bottom composed mostly by algae. Collected and analyzed sediment samples can be classified as biogenic carbonatic sands, as they are composed 75% by calcareous algae, according to the found samples. The most abundant classes are green algae, red algae, nonbiogenic sediments (mineral grains), ancient algae and molluscs. At the parrachos the following was mapped: Barreta Channel, intertidal reefs, submerged reefs, the spur and grooves, the pools, the sandy bank, the bank of algae, sea grass, submerged roads and Rio do Fogo Channel. This work presents new information about geomorphology and evolution in the study area, and will be guiding future decision making in the handling and environmental management of the region

Avaliação da variação sedimentológica em uma área da plataforma continental sob a atuação da indústria petrolífera

Petroleum exploration activity occurs on the offshore Potiguar Basin, from very shallow (2-3 m) until about 50 m water depth, extending from Alto de Touros (RN) to Alto de Fortaleza (CE). Take in account the biological importance and the heterogeneity of sediments on this area, it is necessary the understanding of the sedimentological dynamics, and mainly the changes generated by petroleum exploration to prevent possible damages to environment. Despite the intense activity of oil exploration in this area, research projects like these are still rare. In view to minimize this gap, this study was developed to evaluate sedimentological, mineralogical and geochemical changes in the vicinity of a exploration well, here designated as well A, located on the Middle continental shelf, near the transition to Outer shelf. The well selected for this study was the first one drilled with Riserless Mud Recovery technology (RMR) in Brazil. The main difference from this to the conventional method is the possibility of drilling phase I of the well with return of drilling material to the rig tank, minimizing fluid and gravel discharging around the vicinity, during this phase. Monitoring consisted of three surveys, first of them done before start drilling, the second one done 19 days after the end of drilling and the third one done one year after then. Comparison of the studied variables (calcium carbonate and organic matter content, sediment size, mineralogy and geochemistry) was done with their average, median and coefficient of variation values to understand the changes after drilling activity. Because operating company technical reasons, the well location was changed after the first survey (C1), resulting in a shift of the sampled area on the two last surveys (C2 e C3). Nevertheless, the acquired data presented a good correlation, with no loss to the mean goal of the study. The sedimentological, mineralogical and geochemical analyzes were done at Federal University of Rio Grande do Norte (UFRN). The results indicated a predominantly sandy environment along the three surveys. It was noticed that the first survey (C1), presented different values for all the studied variables than to the second (C2) and third (C3) surveys, which had similar values. Siliciclastic sediments are prevalent at all surveys, and quartz is the main component (more than 80%). Heavy minerals (garnet, turmaline, zircon and lmenite), rock fragments and mud aggregates also was described. Bioclastic sediments are dominated by coralline algae (more than 45%) and mollusks (more than 30%), followed by benthic foraminifera, bryozoans and worm tubes. More rarely was observed ostracoda and spike of calcareous sponge. Because the low changes of the sediments at the studied area and by the using of RMR method in the drilling, it was possible to conclude that drilling activity did not promote significant alteration on the local sediment cover. Changes in the studied variables before and after drilling activity could be influenced by the changing in the sampling area after survey 1 (C1).

Caracterização morfológica-sedimentar do vale inciso Apodi-Mossoró e plataforma continental adjacente - Bacia Potiguar Offshore

Systems of incised valleys have been studied in different continental shelves, including the Brazilian continental margin. The interest to characterize this feature is given by the information that it can provide variations on sea level, as well as the ability to host economically significant quantities of hydrocarbons in reservoirs located in deposits filling of the incised valleys. This thesis has the overall objective to characterize the morphology and sedimentary cover of the incised valley Apodi-Mossoró, located in the Northern Continental shelf of Rio Grande do Norte state, adjacent to Areia Branca city. The methodology included the integration of satellite imagery, bathymetric data, sedimentological data, shallow seismic, and the identification of foraminifera. The results indicate that the ApodiMossró incised valley is currently formed by two channels, shallow channel and deep channel, which have distinct morphological and sedimentological characteristics. The deep channel has connection with one of the heads of the Apodi Canyon, located in the slope area. The acquisition, processing and interpretation of shallow seismic data allowed the recognition of the depositional surface, erosional surface, discordance, and sismofaceis. The erosional surface mapped from shallow seismic sections is possibly a indicative of an ancient surface of valley incision, where it would probably be associated with the limit Pleistocene/Holocene. Different sismofaceis were identified and reflect the rise in sea level with standards sometimes agradacional, sometimes progradational. The thickness of sediments on this surface was estimated at a maximum of 22m thick in the central portion of the incised valley. Statistically, there are differences between the adjacent continental shelf and channels, and between these channels, for the content of calcium carbonate, organic matter, sand and mud perceptual, except for the gravel grain size. The analysis of living and dead foraminifera showed the presence of fifty species distributed in regards to morphology, depth and type of sediment. Four type of seismic echocharacteres were identified and mapped, as well as their bedforms, indicating different sedimentary processes along the incised valley. The integration of results suggests an activation of the Apodi-Mossoró incised valley in the Late Pleistocene.

Foraminíferos, ostracodes e microfauna associada da plataforma continental equatorial norte-rio-grandense, NE Brasil: área Porto do Mangue a Galinhos

This study was conducted in the adjacent Brazilian equatorial inner shelf to Rio Grande do Norte, between the region of Porto do Mangue and Galinhos. The main objective is the characterization of biogenic sediments, especially foraminifera and ostracod collected on the surface of the seafloor. The methodology involved standard procedures including literature, surveys, processing of samples in the laboratory and identification of foraminifera and ostracods by genera or species under stereo microscopy and scanning electron microscopy (SEM). Multivariate statistical analyzes and study of ecological indexes were also applied to the study of foraminifera. Three transects, from inner shelf to slope were sampled: profile 01 (east, near Galos), profile 02 (center, near the city of Macau) and profile 03 (west, near Ponta do Mel). Results indicated the predominance of benthic foraminifera and little plankton occurrence. Benthic foraminifera genera observed in abundance were Quinqueloculina, Textularia, Globigerina and Pyrgo, Quinqueloculina, Textularia, Pyrgo, Ammonia, Elphidium, Pseudononion, Peneroplis, Bolivina and Poroeponides, occurred more frequently. Less frequently been described Amphistegina, Archaias, Bigenerina, Cibicides, Cassidulina, Amphicorina, Cornuspira, Paterina, Hopkunsina, Oolina, Uvigerina, Fusenkoina, Nonionella, Amphisorus, Wiesrella, Reussella, Reophax, Nodosaria, Marginulina and Cyclogyra. Six genera of ostracods were also identified: Puriana variabilis / P. convoluted?, Loxoconcha sp, Bairdiidae, Xestoleberis sp, Hemicytheridae and Ruggiericythere sp. Groups of organisms found in the studied shelf presented chemical composition of Ca, C, O, Na, Cl, Al, Mg, and Si. The proportions of chemical elements may vary according to the type of biogenic sediment, with the highest values identified as Ca, C, Cl, Na and O. The absolute dating by carbon 14 method indicated sediments of different colors (light and dark), correspond to a single age from 3000 to 6000 years BP, related to the Quaternary. These data intend to complement information about biogenic sediments in the Brazilian continental shelf, especially in the Northeast, where there is a lack of such studies.