Mangrove forests and associated gei wai (excavated ponds used for shrimp and fish farming) provide important ecosystem services in Shenzhen Bay. Much of the mangrove and gei wai wetlands, however, have been lost because of intensified human activities in the past 30 years. Using five-phase remote-sensing images, we describe the recent history of the spatial-temporal dynamics for the wetlands in the bay. From 1986 to 2007, mangrove area increased from 1.8 to 4.8 km 2 , while the area of gei wai decreased from 36.6 to 17.2 km 2 . Reclamation of gei wai mainly occurred in western and northern Shenzhen Bay, and changed the tidal water environment. The bay has five typical mangrove communities: Avicennia marina ? Kandelia candel ? Aegiceras corniculatum, Kandelia candel ? Aegiceras corniculatum ? Acanthus ilicifolius, Bruguiera gymnorrhiza ? Excoecaria agallocha, Aegiceras corniculatum, and Sonneratia apetala ? Sonneratia caseolaris. The distribution of these communities and their dominant species in the bay exhibit a spatial pattern and temporal (successional) sequence. We describe a mangrove restoration program based on the mangrove successional sequence and the interaction of mangrove and gei wai in the bay. We have planned six mangrove protection and restoration projects in closed areas, semiclosed areas, and open areas to reconstruct the ecological integrity of the entire Shenzhen Bay.

Background Rapid urbanization has greatly changed land-use patterns in many estuarine areas around the world, including the Guangdong–Hong Kong–Macao Greater Bay Area (GBA) resulting in serious water pollution and ecosystem degradation. Shenzhen City has conducted comprehensive ecological management and restoration in the Shenzhen Bay since 2007. The natural vegetation consisting of mangroves, semi-mangroves, wetland plants, and terrestrial plants were restored from the bund to the inner bank of the Fengtang River. Rain and sewage flow diversion systems were established. The non-point source and point-source sewage are now treated in municipal sewage treatment plants, then naturally flow through the constructed wetland, and then through a natural wetland, restored natural embankment, and finally through mangrove communities substantially improving water quality. Result The restoration of the wetland has increased animal and microbial diversity and has supported the establishment of a complex and stable food web. With water purification and habitat restoration, the number of alien invasive plants in the estuarine ecosystem has decreased, and the diversity of native species of birds, fish, macrobenthos, amphibians, and reptiles has increased. Conclusion These improvements indicate that human beings and nature can coexist in support of the sustainable development of Shenzhen City.