Seasonal Response of Crab Disturbance to nitrogen at the Sediment-Water Interface in coastal tidal wetlands

Abstract

This study is to explore the seasonal response of crab disturbances to nitrogen at the sediment-water interface in coastal tidal flat wetlands, adopting field experiment and indoor control test device. Results showed that crab disturbance showed significant seasonality, and there were significant seasonal differences in cave density and depth. The crab disturbance made the nitrogen flux at the sediment water interface in the crab box much larger than that in the control box. And in summer the NH4+-N showed a positive flux released from the sediment to the overlying water, but the NO2--N and NO3--N showed a positive flux released from the sediment to the overlying water only in early stage. In winter the NH4+-N showed a positive flux released from the sediment to the overlying water, but the NO2--N and NO3--N both showed positive and negative fluxes. These results indicated that the presence of crab burrows could make the aerobic layer move down approximately 8~15 cm in summer and directly promote sediment surface nitrification.