Pico- and nanoplankton abundance and biomass in the Southwest Atlantic Ocean off Brazil

Author(s)

Catherine Gerikas Ribeiro

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto Oceanográfico (IO/DIDC)
• Defense date: 2016-03-23

Examining board members

Frederico Pereira Brandini; Vivian Helena Pellizari; Janaina Rigonato; Fabiano Lopes Thompson; Daniel Vaulot

• Advisor: Frederico Pereira Brandini

Abstract

Flow cytometry (FCM) is a well established technique used for enumeration and characterization of marine biological particles, which fulfills the scientific demands of rapid cell counting automation. FCM allows the discrimination of pico- and nanoplankton populations regarding its abundance, cell size, and pigment content both by natural or induced fluorescence. The cyanobacterium Prochlorococcus is widespread in the euphotic zone of the tropical and subtropical oceans, and is considered the smallest and most abundant photosynthetic organism in the planet. Synechococcus, other important cyanobacterium genus present in the picoplankton, is highly diverse and is widely distributed in marine ecosystems from cold and mesotrophic, to warm, open ocean oligotrophic waters. Photosynthetic pico- and nanoeukaryotes display a range of physiologies and life strategies. Although its abundance is generally lower, the larger cell size leads to a significant contribution to the epipelagic community biomass. In this thesis I aimed to investigate the abundance and carbon biomass distribution of heterotrophic bacteria, Prochlorococcus, Synechococcus, autotrophic pico- and nanoeukaryotes in the Southwest Atlantic Ocean off Brazil, their relation to the different water masses and the influence of hydrodynamic (South Atlantic Central Water intrusion) and biological processes (Trichodesmium spp. and Mesodinium rubrum blooms) on such distributions. (AU)

• FAPESP's process: 12/04800-9 - Diazotrophic community structure along the Brazilian coast and adjacent oceanic area
• Grantee: Catherine Gérikas Ribeiro
• Support Opportunities: Scholarships in Brazil - Doctorate