Effects of increasing atmospheric CO2 on marine microbial communities: a compound-specific isotope approach

• Grant number: 14/04328-3
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: August 01, 2014
• End date: February 08, 2015
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Biological Oceanography
• Principal Investigator: Paulo Yukio Gomes Sumida
• Grantee: Camila Ortulan Pereira
• Supervisor: Dick van Oevelen
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Royal Netherlands Institute for Sea Research, Yerseke, Netherlands
• Associated to the scholarship: 12/14032-9 - Organic matter flow through the benthic communities under higher ocean acidification conditions, BP.DD

Abstract

Uptake of atmospheric CO2 by the oceans already decreased the seawater pH in approximately 0.1 units in a process called Ocean Acidification (OA). Although the ocean chemistry and the changes caused by OA are well understood and can be predicted, the biological effects of ocean acidification are largely unknown. Marine calcifying organisms are especially vulnerable to OA but many important organisms do not depend on calcium carbonate minerals and there is little information about how OA will affect these taxa or the marine ecological process and interactions involving them. It is expected that changes in the carbon fixation by photosynthetic organisms by increased CO2 may alter the biogeochemical composition of them, with indirect consequences to food quality for consumers and trophic interactions. Bacteria in marine sediments are key components in the ecosystem contributing to the cycles of carbon and nutrients through secondary production and remineralization of these compounds. To determine the response of the microbial food web and its pathways it is extremely important to understand the oceans response to increasing CO2 levels, besides providing to identify vulnerable compartments on food webs and improve information for ecosystem protection and management. Due to the difficulty to quantify directly the interactions between primary producers and bacteria in marine sediments, the combination involving mesocosm experiments, stable isotopes and microbial biomarkers techiniques provide a very useful tool to study carbon flows in marine systems. Besides, mathematical models are also useful to quantify budgets and process and to predict the future effect of anthropogenic disturbances. This proposal is part of the ACIDBENTHOS project, (FAPESP process 2010/20350-8) and associated to a doctorate fellowship (FAPESP process 2012/14032-9) and aims to verify whether high CO2 levels affect the transfer of fresh organic matter to the microbial food web. These will be addressed by compound-specific isotope analysis and ecological models, as a way to complete the understanding of all benthic food chain and future effects under global changes. (AU)