Pathways of carbon cycling in fiddler crab burrows and their sedimentary structures in mangroves

• Grant number: 22/14395-6
• Support Opportunities: Scholarships abroad - Research Internship - Scientific Initiation
• Effective date (Start): January 01, 2023
• Effective date (End): April 30, 2023
• Field of knowledge: Biological Sciences - Ecology - Ecosystems Ecology
• Principal Investigator: Tânia Marcia Costa
• Grantee: Tainá Moreira Ferreira
• Supervisor: Cintia Organo Quintana
• Host Institution: Instituto de Biociências (IB-CLP). Universidade Estadual Paulista (UNESP). Campus Experimental do Litoral Paulista. São Vicente , SP, Brazil
• Research place: University of Southern Denmark (SDU), Denmark
• Associated to the scholarship: 22/02276-2 - Mangrove Architects: How can sedimentary structures maximize food capture of fiddler crab?, BP.IC

Abstract

Marine coastal wetlands are considered Blue Carbon Ecosystems because of their high rates of carbon stocks in the sediment. Estuarine organisms manipulate the sediment matrix through their behavior activities and emit a significant amount of CO2 from sediment to the atmosphere, holding a key role in carbon cycling and climate change mitigation. The fiddler crab Leptuca thayeri is one of the most abundant benthic species in mangrove mudflats, building sedimentary structures below (burrows) and above the sediment surface (e.g., chimneys). Chimneys possibly amplify the capture of particles suspended in the water column, also amplifying the particle trap function of crabs burrows. In this sense, we aim to investigate the microbial processes of carbon mineralization in fiddler crab burrows and the potential effect of chimney structures in the capture of the particles. We will perform a time series of anoxic incubations of the burrow wall sediment and burrow chimney sediment, moreover, a sediment without burrow to understand how the carbon mineralization of deposited organic material and which pathway is responsible for it (iron respiration and sulfate reduction). Stable isotope analysis will be done to analyze food sources for microbes and fiddler crabs. The sampling and experiment will be conducted in November-December in Praia Grande (São Paulo, Brazil) and all analyses will be performed at the University of Southern Denmark, Odense. The results will provide rates of iron respiration, sulfate reduction, and total rates of carbon mineralization in burrow wall and burrow chimney sediments. Therefore, observations of the sediments will provide insight about C cycling and blue carbon processes and their relation with climate change.