A physical-biogeochemical mechanism for negative feedback between marsh crabs and carbon storage

Julia Guimond, Angelia L Seyfferth, Kevan Moffett, Holly Michael
2019 Environmental Research Letters  
34 Tidal marshes are valuable global carbon sinks, yet large uncertainties in coastal marsh 35 carbon budgets and mediating mechanisms limit our ability to estimate fluxes and predict 36 feedbacks with global change. To improve mechanistic understanding, we assess how net carbon 37 storage is influenced by interactions between crab activity, water movement, and 38 biogeochemistry. We show that crab burrows enhance carbon loss from tidal marsh sediments by 39 physical and chemical feedback
more » ... ses. Burrows increase near-creek sediment permeability in 40 the summer by an order of magnitude compared to the winter crab dormancy period, promoting 41 carbon-rich fluid exchange between the marsh and creek. Burrows also enhance vertical 42 exchange by increasing the depth of the strongly carbon-oxidizing zone and reducing the 43 capacity for carbon sequestration. Results reveal the mechanism through which crab burrows 44 mediate the movement of carbon through tidal wetlands and highlight the importance of 45 considering burrowing activity when making budget projections across temporal and spatial 46 scales. 47 48
doi:10.1088/1748-9326/ab60e2 fatcat:rjtsbpmg75d6hif3jyqcnbouti