Research on bio-morphodynamic processes of Aegiceras corniculatum in the Nanliu River Estuary

Aegiceras corniculatum is one of the pioneering mangroves. The coupling process involving A. cornicu-latum development and tidal flat geomorphological evolution is one of the core contents of mangrove bio-morpho-dynamic and ecological restoration research. Based on high-resolution remote sensing images between 2005−2019, monthly sediment and A. corniculatum population samples from October 2019 to October 2020, the variation characteristics of A. corniculatum distributed over the tidal flat of the Nanliu River Estuary were analyzed. Meanwhile, the coupling mechanism between the morphological changes of tidal flat erosion/accretion and the population expansion of A. corniculatum was discerned. The main results can be shown as follows: (1) it is found that the main grown area of A. corniculatum is the outer sides of the levees of Nanliu River Estuary. The distribution of the adult, youth and embryos of A. corniculatum presented bandy features along the high tidal flat, middle tidal flat and the area near mean sea level, respectively. Furtherly, tidal flat elevation of 0.07 m above the mean sea level is the growth limit of annual seedling. (2) A. corniculatum of the Nanliu River Estuarine flat expanded rapidly from north-west to southeast, which is in coincidence with development tendency of tidal flat. Tidal flat height is elevated with possibility for mangrove habitation, which should be necessary for A. corniculatum promoted seaward progradation. (3) A. corniculatum that induced wave attenuation can mitigate hydrodynamics forcing with benefit to tidal flat sedimentation, which can furtherly have tidal flat accreted seaward. Moreover, the low tidal flat can be elevated into the middle-high tidal flat by silting, which provides growth and development conditions for A. cornicu-latum.