Plankton and particle biomass size spectra on the Southwest Atlantic: Case studies in tropical and subtropical areas

• Ano de defesa: 2013
• Autor(a) principal: Marcolin, Catarina da Rocha
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Atlântico Sudoeste; Brasil; Brazil; estratificação; NBSS; plâncton; plankton; productivity; produtividade; Southwest Atlantic; stratification
• Link de acesso: http://www.teses.usp.br/teses/disponiveis/21/21134/tde-12052014-173357/

This thesis is centered on the application of the Normalized Biomass Size Spectra (NBSS) theory to the study of plankton systems in shelf and oceanic areas of the tropical and subtropical Southwest Atlantic. I evaluated NBSS parameters over different environmental settings and their utility as proxies for system in Brazilian waters. The LOPC and the ZooScan are recently developed optical systems to automatically detect and measure plankton and particle size distributions in situ and in laboratory, respectively. I present two case studies: the first deals with the spatial variability over the Abrolhos Bank and adjacent oceanic areas in tropical latitudes, and the second focuses on temporal variability of plankton communities along a 5-year time series on a fixed station on the inner shelf at a subtropical location (Ubatuba, São Paulo). The data sets consisted of vertical profiles obtained with a LOPC and plankton preserved samples collected with a 200-m-mesh net. I observed in both data sets the accumulation of small particles (< 1 mm) above and within the pycnocline. NBSS slopes and intercepts were significantly different according to the contrasting environmental conditions observed in both areas; higher intercepts and steeper slopes were associated with higher productivity. The results highlight: i) water-column stratification as a key feature driving particle and plankton vertical distribution, ii) NBSS parameters as indicators of different environmental settings, and iii) that the cold and nutrient-rich South Atlantic Central Water (SACW) have an important role structuring the zooplankton size distributions over the Abrolhos Bank and vicinities and off Ubatuba. The NBSS parameters associated with information on plankton composition and distributions provided important information to evaluate the influence of oceanographic forcing on plankton dynamics in distinct ecosystems of the Southwest Atlantic