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14 results on '"Gaeta, Salvador Airton"'

8. Diel variations in chiorophyll α phytoplancton primary production and enviromental factors from Ubatuba regiion (Lat. 23º30'S Long. 45º06'W)

Author

Teixeira, Clóvis and Gaeta, Salvador Airton

Subjects
Variação nictemeral, Primary production, Fatores ambientais, Chlorophyll a, fungi, Fotossíntese, Ubatuba, Clorofila a, Environmental conditions, Photosynthesis, Produção primária, Diel variation
Abstract

A series of experiments with natural phytoplankton populations was carried out to study the diel variation of chlrophyll a, primary production and some environmental factors. Samples were collected from surface over a period of 24 hours and always from one fixed station located in Flamengo Inlet, Ubatuba region, southern Brazil The experiments were performed in situ and simulated conditions to verify the patterns of diel cycles of both biotic and abiotic factors. The results obtained showed that diel variations were markedly pronounced mainly in relation to primary production and chlorophyll a. Diel variations of biological factors seems to be due to exogenous and endogenous phenomena.

Published
1991

12. Observações preliminares sobre a toxicidade do ϒBHC e do cloreto de mercúrio à Artemia salina

Author

Gaeta, Salvador Airton, Kadekaru, Naoko, Pereira, Norival, and Tommasy, Luiz Roberto

Subjects
Larvas, Larvae, Heavy metals, Metais pesados, Pesticides, Bioensaios, Pesticidas, Artemia salina, Bioessays
Abstract

Results of bio-assays using Artemia salina larvae in γBHC-HgCl2 mixture are presented. The results obtained are compared with those obtained using the two chemicals separately. The LC50 for γBHC was almost double that for HgCl2. The effect due to the primary dose of HgCl2 was observed for approximately 16% of the population (LC2.3) while for γBHC the population percentage was 2.3 (LC2.3). As a consequence, subsequent doses were more effective for HgCl2 than for γBHC. The effective dose 50% (ED50) is about the same for γBHC and for γBHC + HgCl2 mixture, though in higher doses BHC would be more effective, while in smaller doses the mixture would predominate. São apresentados os resultados de bioensaios com larvas de Artemia salinacolocadas em misturas de γBHC e HgCl2, a fim de se compararem os efeitos das mesmas com aqueles obtidos quando essas duas substancias atuam isoladamente. A CL50 para o yBHC foi quase que o dobro do valor para o HgCl2. O efeito da primeira dose foi observado para aproximadamente 16% da população (CL16), enquanto que, para o γBHC, o foi em 2,3% da população (CL2,3). Assim, as doses subseqüentes foram mais efetivas para o HgCl2 que para o γBHC. A dose efetiva 50% (ED50) ê mais ou menos igual para o γBHC e para o γBHC + HgCl2, mas em doses altas o YBHC seria mais efetivo, enquanto que em doses baixas a mistura e que o seria.

Published
1983

14. Benthic community structure and organic matter variation in response to oceanographic events on the Brazilian SE inner shelf.

Author

Rodrigues Alves, Betina G., Güth, Arthur Ziggiatti, Bícego, Márcia Caruso, Gaeta, Salvador Airton, and Gomes Sumida, Paulo Yukio

Subjects
*BENTHIC ecology, *CARBON content of water, *BIOTIC communities, *OCEANOGRAPHY, *COMPOSITION of sediments, *CONTINENTAL shelf
Abstract

For 13 months, this study monitored the sedimentary organic matter composition, benthic bacteria and macrofauna at a permanent sampling station on the inner shelf (~ 40m depth) near Ubatuba in SE Brazil. The sedimentary organic matter compounds were evaluated for total organic matter content, lipid biomarkers and phytopigments. The organic matter content varied significantly over time but no clear seasonal trend was evident. Lipid biomarker composition revealed that particulate organic matter was primarily derived from autochthonous sources, such as diatoms, other microalgae, zooplankton, sediment bacteria and benthic metazoan fauna. Phytopigment results revealed that the majority of the organic matter in the sediments was refractory as opposed to labile, suggesting that the labile portion is rapidly consumed. The benthic dynamics off the coast of Ubatuba is highly influenced by the intrusion of the South Atlantic Central Water (SACW) onto the shelf, which brings nutrients up to the euphotic zone and stimulates new phytoplanktonic production. This enhances the flux of organic matter to the bottom and increases benthic biota density, mainly bacteria. These results suggest a strong and complex benthic-pelagic coupling that is influenced by both mesoscale oceanographic events (i.e., intrusion of SACW) and local events (cold fronts) through remobilization of the sediments. [ABSTRACT FROM AUTHOR]

Published
2014
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