The relationship burrows of Macrophthalmus japonica and utilization DIN by microphytobenthos in river mouth tidal flat was evaluated. Seasonal variation and temporal variation about DIN for one tide were investigated in the crab burrows. Though dissolved oxygen decreased during ebb tide for respiration by crab and organic decomposition, NH4+-N in the burrows increased for metabolism by crab and elution from wall surface. Burrows supplied DIN for tidal flat area in flood tide and microphytobenthos efficiently assimilated DIN. It found that burrows served DIN for microphytobenthos as fertilizer application.
