Baseline:
Mangroves refer to woody plant communities growing in tidal wetlands that mainly include Rhizophoraceae, primarily in tropical and subtropical regions, regularly submerged by tidal waters. With unique hydrological, biogeochemical, and ecological functions, mangroves stand as one of the Earth's ecosystems with the richest biodiversity and highest value in ecosystem services. However, due to the dual impacts of human activities and global climate change, the mangrove areas worldwide are sharply declining, facing many challenges such as local habitat degradation, biodiversity loss, and invasive alien species.
According to the unified accounting results for the GDP in Shenzhen, the GDP of Futian District in 2022 reached 551.449 billion yuan, up 3.0% y-o-y. The value added in the primary sector was 173 million yuan, up 1.4%. The value added in the secondary sector was 50.429 billion yuan, down 1.9%. Meanwhile, the value added in the tertiary sector amounted to 500.847 billion yuan, up 3.6%. The GDP per km2 reached 7.011 billion yuan, ranking first among all districts in Shenzhen and indicating its rapid economic development.
In 2012, at the 18th National Congress of the CPC, the development of ecological civilization was incorporated into the overall layout of socialist modernization, with a focus on ecological and environmental protection. On April 19, 2017, during an inspection tour of the mangroves in Jinhai Bay, Beihai, Guangxi, Chinese president Xi Jinping emphasized the need to "respect science and fulfill responsibilities in order to well protect mangroves." In August 2020, the Ministry of Natural Resources and the National Forestry and Grassland Administration (NFGA) of the People?s Republic of China jointly issued the "Mangrove Protection and Restoration Action Plan (2020-2025)" (the "Action Plan"), outlining the fundamental principles, action objectives, key actions, and safeguard measures for mangrove protection and restoration in China over the next five years. A series of measures highlight the nation's emphasis on the importance of protecting and restoring mangrove wetlands, hoping to expedite and enhance the mangrove wetland conservation and restoration efforts along a more science-based and reasonable pathway.
The Shenzhen Bay mangrove wetland stands as a verdant ?oasis? between the two modernized cities of Shenzhen and Hong Kong. It mainly consists of two parts: Futian Mangrove Nature Reserve, China's only mangrove protected area at the national level which is nestled in the heart of the city; and the Mai Po Nature Reserve, a Ramsar site in Hong Kong. This wetland not only hosts large areas of precious mangrove plants, but also provides a habitat for numerous rare animals. Annually, it offers a habitat for tens of thousands of migratory birds along the East Asian?Australasian Flyway (EAAF), making itself become one of the most significant wetland ecosystems in South China with international importance. In recent years, however, the Shenzhen Bay wetlands are facing various disturbances and threats from both existing and potential external factors, such as the degradation of mangrove structure, the encroachment of non-native mangroves into tidal flats, and biodiversity loss.

Problems:
With an extremely high seed-setting rate, the mature plants of these non-native mangroves can grow from seeds to 3 meters in height and start fruiting within a year. By 2017, the Sonneratia mangroves at the Shenzhen River Estuary had expanded from the original 2 hectares to nearly 20 hectares. Additionally, the sedimentation process of the Sonneratia mangrove forest and the siltation of the Shenzhen River Bay have accelerated the accumulation of sediments in the estuarine area of mangrove tidal mudflats. As a result, natural tidal dynamics are no longer sufficient to provide adequate water movement in the Shenzhen River Estuary mangrove wetland. This has resulted in the prolonged water retention within the mangroves, poor exchange of water, and deterioration of the tidal mudflat environmental conditions. Moreover, the uncontrolled growth of Sonneratia mangroves has narrowed the flood discharge section of the Shenzhen River channel, increasing flood control pressures on the upstream river channels.
For this reason, there is an urgent need to control the disorderly expansion of the non-native Sonneratia mangrove species in the Shenzhen River estuary and to prevent their further encroachment into native mangrove habitats. Meanwhile, some areas of bare mudflats should be cleared to restore and preserve ample foraging spaces for migratory birds. The structural composition, growth patterns, and biodiversity impacts of Sonneratia mangrove community, as an invasive alien species in Shenzhen Bay, have raised concern for a long time. As its seedlings are spread to adjacent areas such as Mai Po in Hong Kong and Deep Bay Ramsar Site, it has aroused great attention from scholars and wetland management authorities in Hong Kong. The removal of Sonneratia has been incorporated into the management plans of local government agencies. Nevertheless, there is still an ongoing heated debate within the academic community about whether Sonneratia mangroves in Shenzhen Bay should be officially classified as invasive plants. Government authorities remain cautious about non-native mangrove clearance efforts and their effectiveness. Therefore, there is an urgent need for a pioneering and representative project of integrated management to establish a precedent for comprehensive control measures in Shenzhen Bay.
Meanwhile, the emergence of environmental problems in coastal wetlands, such as the introduction and spread of Sonneratia mangrove species, the reduced mangrove wetland areas, and habitat destruction, are all closely related to modern human activities. Enhancing people?s environmental literacy, therefore, is crucial to addressing these environmental challenges. The primary and secondary school students are in their crucial periods of forming their habits and values, and developing their environmental literacy. By conducting environmental education for these students, we can help develop their environmental literacy, focusing on awareness, knowledge, attitudes, skills, and actions, and, in turn, raise their awareness, knowledge, and abilities in the protection of coastal wetlands.

Activities:
Activity 1.
Develop a project plan for maintaining the 18-hectare mangrove wetland in the Shenzhen River estuary, clearing and maintaining a 9-hectare bare mudflat

Activity 2.
Conduct bird and mammal surveys in the Shenzhen River estuary area, monitor changes in bird populations and mammal activities before and after project implementation, assess the effectiveness of mangrove wetland protection and management, and summarize project experiences
Activity 3.
Develop wetland education courses and conduct wetland education activities for primary and secondary school students in Shenzhen City

Outcomes:
Ecological restoration and habitat protection: Since its introduction in 1993, the non-native Sonneratia mangrove plants have continuously expanded, encroaching into the mudflats of the Shenzhen Bay estuary. This expansion has altered the pattern of the mangrove forests in Shenzhen Bay, promoting mudflat siltation, reducing the water surface area of the river channels, and affecting flood discharge. Implementing this project can help effectively restrain the continuous expansion of Sonneratia mangrove plants, providing living space for native Rhizophoraceae plants and enhancing the diversity of the plant communities. Meanwhile, the removal of Sonneratia mangrove plants can contribute to mud flushing, expanding the water surface area, and reducing the flood control pressure on the upstream channels of the Shenzhen River and Xinzhou River. Furthermore, benthic organisms, waterfowl, and other living organisms are also affected by the expansion of Sonneratia mangrove plants. In particular, Shenzhen Bay is located at the midpoint of the EAAF, serving as a wintering, stopover, and refueling site for migratory birds, with approximately one hundred thousand migratory birds stopping here annually. The rapid expansion of Sonneratia mangrove plants has promoted mudflat siltation, and accelerated the expansion of native Rhizophoraceae. This has reduced foraging and living spaces for birds, and negatively affected the survival of a large number of migratory birds. To address this problem, the project will curb the spread of Sonneratia mangrove plants, maintain the area of mudflats, enhance wetland biodiversity, and, in turn, safeguard the foraging and living spaces for birds. By analyzing and summarizing the project outcomes, the project will develop cases that can be disseminated, thus contributing to the control of Sonneratia mangrove plants at large scale across the country.
Influence and demonstration: The project will, through pilot initiatives, explore experiences in effectively controlling the spread of exotic plants, and create outstanding cases in this field. The success of past experiences has allowed local government authorities in water affairs, ecology, protected area management, and planning and natural resources, etc. to reach a consensus on "Controlling the spread of exotic Sonneratia mangrove plants to promote overall protection of the Shenzhen Bay mangrove wetlands." These local government authorities have leveraged their respective strengths to support the ongoing implementation of the wetland restoration projects. This support includes the government's establishment of a special project for monitoring the effectiveness in restoring the Shenzhen River estuarine wetlands, which aims to summarize experiences in wetland restoration for wider dissemination and expansion. Additionally, the Shenzhen and Hong Kong governments have jointly launched a project to remove Sonneratia mangrove plants along the Shenzhen River section.
In the early stages of artificial afforestation in mangrove restoration projects, Sonneratia apetala and Laguncularia racemosa are the two most widely used exotic Rhizophoraceae species, which are characterized by fast growth and strong stress resistance. In particular, Sonneratia apetala is estimated to cover an afforestation area of about 2,500-3,000 hectares, accounting for approximately 17% of China's total mangrove area. However, its monoculture structure and poor stability pose the risk of ecological invasion. The removal and transformation of pure stands of non-native Sonneratia mangroves will be an issue to be widely addressed in the future restoration of mangroves across different regions in China. However, there is currently a lack of research and case study concerning the restoration of bare mudflats and sustainable maintenance, the alternative restoration of native Rhizophoraceae, especially through natural recovery, and the effectiveness on the enhancement of biodiversity. The restoration, experimentation, and ongoing monitoring of the mangrove wetlands at the Shenzhen River estuary is expected to provide valuable insights for mangrove restoration efforts and the sustainable management of mangrove ecosystems in other regions across the country.
Raising public awareness: Targeting local primary and secondary school students, the project will develop four wetland education courses in the process of implementing coastal wetland ecological restoration project. Students from 50 classes in Shenzhen will be organized to participate in outdoor wetland education courses, aiming to enhance students' ecological literacy in various aspects, including environmental awareness, knowledge, and skills.