ORIGIN AND COMPOSITION OF THE ORGANIC MATTER AND THE MICROBIAL DYNAMICS IN SURFACE SEDIMENTS OF MARINE ECOSYSTEMS FROM THE SE BRAZILIAN COAST

Author(s)

Marcos Yukio Yoshinaga

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto Oceanográfico (IO/DIDC)
• Defense date: 2007-03-01

Examining board members

Paulo Yukio Gomes Sumida; Renato da Silva Carreira; Michel Michaelovitch de Mahiques; Renato Rodrigues Neto; Ana Maria Setubal Pires Vanin

• Advisor: Paulo Yukio Gomes Sumida

Abstract

The cycling of the organic matter (OM) in the marine environment is a key process in the global carbon cycle. Coastal sediments are important to the global carbon cycle, since they receive large inputs from both marine and terrestrial OM. The myriad of organic compounds and their spectrum of reactivity complicate the understanding of OM sources in coastal environments. In this work, we aimed to access the origin and composition of the OM (through lipid biomarkers) and the microbial dynamics (ATP method) in surface sediments of diverse marine ecosystems from the SE Brazilian coast: (i) the continental margin off Cabo Frio; (ii) the lagoonal system of Saquarema; (iii) coastal and shelf areas from Ubatuba; and (iv) the continental shelf adjacent to Santos estuary. The results showed a dominance of autochthonous OM, with a minor fraction of the OM derived from terrestrial sources and restricted to areas close to the coast. Oceanographic processes and environmental forces are crucial to the composition of sedimentary OM and are discussed for each of those ecosystems. (AU)