Sediment distribution in shallow estuaries at fine scale: in situ evidence of the effects of three-dimensional structural complexity of mangrove pneumatophores

One of the main services offered by mangroves is their capacity for trapping sediment. We investigated how spatial complexity of pneumatophores of Avicennia marina may influence fine-scale sediment particle size distribution. Using realistic three-dimensional models captured from pneumatophore patches, indices of complexity (the area/volume ratio, the Getis-Ord Gi* statistic) were calculated to quantify mangrove root structural complexity in five 1 × 1 m 2 plots. The complexity of pneumatophores in 16 0.25 × 0.25 m 2 subplots in each of the 5 plots was measured and its relationship with the relative abundance of fine sediment particles (clay and silt,