Navegando por Assunto "Plataforma Continental"

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Acesso aberto (Open Access)
Avaliação geoquímica da ocorrência de metais pesados selecionados em sedimentais pelíticos da plataforma continental do Amazonas no trecho entre a foz do rio Pará e o cabo Orange
(Universidade Federal do Pará, 2003-04-10) LIMA, Edgar Alexandre Reis de; LIMA, Waterloo Napoleão de; http://lattes.cnpq.br/1229104235556506
Acesso aberto (Open Access)
Dinâmica espaço-temporal da pesca industrial de camarão-rosa Farfantepenaeus subtilis na plataforma continental do Amazonas
(Universidade Federal do Pará, 2011-05-18) MARTINS, Déborah Elena Galvão; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252; CAMARGO-ZORRO, Mauricio; http://lattes.cnpq.br/5423657235023988
Knowledge of spatial distribution of fishing resources is essential to fisheries management. The southern brown shrimp Farfantepenaeus subtilis (Perez-Farfante, 1967) is an industrial fishing fleet target on the Amazon Continental Shelf. This study aimed to evaluate F. subtilis relative abundance spatial-temporal patterns from commercial fishery data, using Geographic Information System tools. Catch per unit effort (CPUE), used as index of relative abundance, was related to bathymetry, substrate characteristics, Amazon river flow and the oceanographic variables obtained by remote sensing: sea surface temperature and chlorophyll-a concentration. Analyzing substrate characteristics, the commercial shrimp trawls were concentrated at the mottled mud region, where the overlap of environmental factors was crucial for a higher incidence of F. subtilis. In this region, features such as substrate (mud), sedimentation rate (<1 cm.yr-1) and salinity (> 30) are the ideal habitat for F. subtilis. Higher CPUE values were associated with lower temperatures and higher values of chlorophyll-a concentration, which occur at the greatest flow of the Amazon river, during the first six months of the year. It was observed the occurrence of three periods with different levels of production along the year: from February to April, with higher CPUE of southern brown shrimp, from May to July, and August to September, with lower CPUE. The results showed that relative abundance of F. subtilis is not distributed uniformly in space nor in seasonal variation.
Acesso aberto (Open Access)
Estudo das diferentes formas de fósforo nas águas da plataforma continental do Amazonas
(2007-06) SANTOS, Maria de Lourdes Souza; COSTA, Katia Muniz Pereira da; FEITOSA, Fernando Antonio do Nascimento; BARROS NETO, Benício de
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.
Acesso aberto (Open Access)
Nutrient and phytoplankton biomass in the Amazon River shelf waters
(2008-12) SANTOS, Maria de Lourdes Souza; MUNIZ, Kátia; BARROS NETO, Benício de; ARAUJO, Moacyr Cunha
The Amazon River estuary is notable at the Amazon Continental Shelf, where the presence of the large amount of water originating from the Amazon during the river's falling discharge period was made evident by the low salinity values and high nutrient levels. Even so, the presence of oceanic waters in the shelf area was significant. Dissolved organic nitrogen was the predominant species of the nitrogen cycle phases, followed by total particulate nitrogen, nitrate, ammonium and nitrite. The chlorophyll a data in the eutrophic area indicated that there is sufficient nitrogen in the area to withstand productivity, though dissolved inorganic nitrogen removal processes are faster than regeneration or mineralization. The anomalous amounts of inorganic dissolved nitrogen showed more removal than addition. The simulations with the bidimensional MAAC-2D model confirmed that high nutrient waters are displaced northwest-ward (two cores at 2.5ºN-50ºW and 4ºN-51ºW) by the stronger NBC during falling river discharge. During high river flow period these nutrient-rich lenses are distributed around 0.5ºN-48.5ºW as well as along the shallow Amazonian shelf (20m-50m depth, 1ºN-3.5ºN), as a result of the spreading of Amazon freshwater outflow.