Chemosynthesis in marine sediments at Rio Grande rise, Southwestern Atlantic Ocean

• Grant number: 17/02409-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): August 01, 2018
• Effective date (End): July 31, 2019
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Biological Oceanography
• Principal Investigator: Camila Negrão Signori
• Grantee: Carolina da Luz Soares Viscarra
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 14/50820-7 - Marine ferromanganese deposits: a major resource of E-tech elements, AP.TEM

Abstract

Deep-sea environments are still poorly studied from a microbial perspective, even though they are known for the dominance of microorganisms in sediments in terms of biomass and metabolism, and their pivotal contribution to biogeochemical cycles and benthic trophic chain through autotrophic and heterotrophic processes. Thus, studies in Microbial Oceanography that investigate carbon assimilation in the dark by the process of chemosynthesis are essential for better understanding the role of microbes in the deep ocean. The main goal of this Project is to quantify the microbial chemosynthetic production in the deep-sea sediments in the region of the Rio Grande Rise (RGR), Southwestern Atlantic, comparing it with the rates obtained in the water column. This area, which encompasses different oceanographic features (crust, seamounts, polymetallic nodules), lacks studies in respect of local microbial processes and their contribution to the carbon cycle. Sediment samples will be collected at ten sampling points, corresponding to depths between 500-5000 m, and incubated with 14C-bicarbonate in the dark for 6-12 hours. The chemosynthetic rates will be calculated in gC/L.h from the results obtained in the liquid scintillator. Statistical analyzes will be performed to check the influence of physical and chemical factors of the sediments on microbial production. We hope to obtain good data in a poorly studied area, that may contribute to a better understanding of the chemosynthetic microbial role in the deep ocean of RGR. (AU)