For my master's thesis at Villanova University, I studied the effects crab bioturbation (burrowing) on mangrove productivity.  I found that organic matter decomposition increased with crab burrow density, and that decomposition negatively correlated with mangrove internode length. In addition, I found that crab bioturbation did not impact the belowground productivity of the wetland vegetation. Thus, my findings suggest that crab bioturbation is antagonistic to mangrove growth and poleward encroachment by indirectly hindering the aboveground internode growth of mangroves. I also found that the production of pneumatophores increased with the density of crab burrows. My findings indicate that burrowing crabs may induce nutrient export from the sites via sediment suspension during tidal flow, all dynamics that can be ultimately driven by elevation. I also suggest that elevation remains an important covarying factor with crab activity and pneumatophore abundance that was not measured in this study that may have helped explain my data. This knowledge can be used to narrow down the controls on mangrove productivity - an important consideration when quantifying carbon capture of these excellent carbon trapping ecosystems.

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Principal Investigator - Samantha Chapman, Ph.D.