Schematic summary of four key driving mechanisms showing how fiddler crab burrowing affects carbon burial through direct and indirect pathways in different habitats. Mechanism 1, mineral affinity dimmish: labile molecules and Fe-Mn minerals are released from sediment clay, followed by labile molecules that are utilized by microorganisms and become recalcitrant molecules, with Fe oxides being reduced and oxidizable Mn minerals oxidized; Mechanism 2, redox switch: frequent aerobic-anaerobic shifts in crab burrows cause continuous molecule release and oxidation; Mechanism 3, climate regulate: greater rainfall lowers NOSC in DOM. Environmental energy constraints preserve labile molecules by slowing organic matter conversion; Mechanism 4, hydraulic exchange: during hydraulic exchange, bioturbation destabilizes coastal sediment and affects the transport of sediment nutrients. For example, released DOC is partly transported offshore through burrow flushing and groundwater discharge. Some of this DOC is oxidized to CO₂ and DIC, which is released into the atmosphere and ocean.