Working with Natural Cohesive Sediments

Summary of Stabilizing and Destabilizing Biotic Influenceson Natural Cohesive Sediment STABILIZING DESTABILIZINGEPS secretion : Extracellularpolymeric substances bybacteria and microphytobenthosenhances cohesion, promotesflocculation and hence deposition Blistering : Trapping ofoxygen bubbles in biofilmsincreases buoyancy of thebiofilm to such an extentthat it pulls away fromthe sediment Sediment compaction :Burrowingmacrofauna increasesediment densityand hence stability Pelletization : Theformationof faeces and psuedo-faeces can enhanceerodibility Increased drainage : Burrowand channel formationpromotes dewatering Grazing : Organismsfeedingon intertidal flats causesphysical disturbance andresuspensionof the sediment andreduces the stabilizinginfluence ofmicrophytobenthos Network effects : Filamentous biotaramify through the sediment matrixbinding sediment particles together Burrow cleaning : Somebenthic fauna cleantubes they inhabit inthe sediment giving riseto a localizedbenthic flux Flow effects