Distribuição espacial do pico e ultraplâncton na plataforma continental e talude entre Cabo Frio (RJ) e Ubatuba (SP) e sua relação com a hidrodinâmica local: inverno de 2010

• Ano de defesa: 2012
• Autor(a) principal: Castro, Nathália Oliveira de
• Orientador(a): Moser, Gleyci Aparecida Oliveira
• Banca de defesa: Guerra, Josefa Varela , Nascimento, Silvia Mattos
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade do Estado do Rio de Janeiro
• Programa de Pós-Graduação: Programa de Pós-Graduação em Oceanografia
• Departamento: Centro de Tecnologia e Ciências::Faculdade de Oceanografia
• País: BR
• Palavras-chave em Português: ACAS; Fatores bottom-up; Picoplâncton; Ultraplâncton; Mesoescala
• Palavras-chave em Inglês: SACW; Bottom-up factors; Picoplankton; Ultraplankton; Mesoscale
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::OCEANOGRAFIA
• Link de acesso: http://www.bdtd.uerj.br/handle/1/13872

The picoplankton (0.2 2.0 µm) and ultraplankton (>2.0 5.0 µm) arouse interest because they actively use the dissolved organic matter and establishe the microbial loop. Responsible for 50-80% of primary production in oligotrophic waters, these fractions have high luminous efficiency and high surface/volume ratio that enable them to achieve high development even under low light and low nutrient availability. Seeking to relate the spatial distribution and composition of pico and ultraplanktonic community to the bottom-up control and mesoscale oceanographic features in the Brazilian continental shelf and slope off Rio de Janeiro and São Paulo (22°S to 26°S), water samples were taken in 39 oceanographic stations and images of MODIS Terra and Aqua sensors, toghether with hidrography, were employed to decribe the mesoscale oceanographic features.The total abundance of both size fractions, as well as the dominance of picoplankton, decreased as a function of distance from the coast. Autotrophic organisms were, predominantly, on average (102 cell.mL-1 to 104 cell.mL-1) one order of magnitude lower than the heterotrophic (103 cell.mL-1 to 105 cell.mL-1). The South Atlantic Central Water (SACW) and the plumes of Guanabara and Sepetiba bays (RJ) remained in the inner shelf favoring an increase in macronutrients concentration and reflecting changes in community structure by the increase of autotrophs contribution, especially in the central portion of the shelf, mainly ultraplankton at surface (21%) and in maximum chlorophyll depth (44%). The transport of coastal waters carried by a current from south caused the shelf eddy identified by water colour/chlorophyll images for the region of Ubatuba inner shelf (SP), where high concentrations of ammonium (0,28 µM) and phosphate (9,64 µM) near the depth of 50 m supported higher density of autotrophic ultraplankton (2.89 x 103 cells.mL-1) which exceeded the density of heterotrophs at the chlorophyll maximum (2.19 x 103 cells.mL-1). Our results highlighted a strong neritic-oceanic gradient in the distribution of these organisms. They also suggest the predominance of the heterotrophic metabolism in the majority of the oligotrophic waters of the shelf and slope between Rio de Janeiro and São Paulo, as well as the presence of an autotrophic nature in those regions influenced by mesoscale features, such as estuarine plumes and shelf eddies.