Fujian Minjiang River Estuary: The ecotone between marine and terrestrial biogeographical regions

Description

As the largest independent water system in Fujian Province, Minjiang River is also a relatively large independent water system along the southeast coast of China. Most of the tributaries in the upper reaches of Minjiang River originate from Wuyi Mountains. The middle reaches flow through a large area of red sandstone and granite denudation area. The river finally flows into the East China Sea in the northeast of Changle District, Fuzhou. Minjiang River Basin has outstanding universal value in terms of natural beauty, geological landform, biological and ecological processes, as well as biodiversity, which have been recognized internationally. Wuyishan World Cultural and Natural Heritage and Fujian Taining Area of China Danxia World Natural Heritage are located in the Minjiang River Basin. Moreover, Minjiang River Estuary lies at a special position in biogeographic division. Wetlands and the surrounding offshore waters at Minjiang River Estuary provide key habitats for a variety of globally endangered species, especially migratory birds. Under the joint action of natural forces and human activities in recent millennia, the wetlands and offshore areas here still accommodate rich and unique biodiversity, and have become the foundation for the survival of various migratory birds in the EAAF, various large marine animals migrating offshore in the northwest Pacific and the fishery-agricultural traditional communities living in coastal areas. The wetlands and sea at Minjiang River Estuary comprise a special place, where a great river with rich outstanding universal value flows into the Pacific Ocean, and also connects two terrestrial and two marine ecoregions. More importantly, it is a place which can not only allow the people to catch a glimpse of the active natural evolution process in the eastern coast of China, but also make it possible for people to explore the ways to achieve coexistence with the terrestrial and marine ecosystems and realize sustainable development.

Minjiang River Estuary is located at the ecotone of two terrestrial biogeographic provinces and two marine ecological regions. Its ecosystem diversity and species diversity have prominent regional characteristics. From the perspective of global terrestrial biogeographic division, the terrestrial side of Minjiang River Estuary is located at the transitional zone between China Subtropical Forest (No. 2.1.1) and South China Rainforest (No. 4.6.1) in terms of Udvardy’s global biogeographic region. It is also the transitional zone between the hilly plain subregion in the east of central China (No. VIA) and the Fujian- Guangdong coastal subregion in South China (No. VIIA) in terms of zoogeographic division of China. In the zoogeographic regions of China, the intersection of regions No. VIA and No. VIIA on the coastline of mainland China happens to be located at Minjiang River Estuary. From the perspective of global marine biogeography, the marine side of Minjiang River Estuary is part of the transition ecotone between Warm Temperate Northwest Pacific (No. 9) and South China Sea (No. 25).

These transitional features in biogeographical regions make the biodiversity of wetlands and offshore areas of Minjiang River Estuary extremely rich. Minjiang River Estuary is situated at the northern edge of mangrove’s distribution range in the coastal area of the Asian continent, and the southern edge of the distribution range of Scirpus mariqueter (means natural hybrid species, according to the taxonomic system of Flora of China) community. On the intertidal mudflats, the zonal distribution of Scirpusmariqueter, mangrove (Kandelia candel) and reeds communities is a special horizontal vegetation zone spectrum only found in the coast of south Zhejiang and north Fujian. In the terrestrial side, there is Cyperus malaccensis subsp. monophyllus community, which is a typical emergent aquatic plant community in South China.

The abundant fish and benthic animal resources which are nourished by large amount of sediments and nutrients carried into the sea by Minjiang River, have attracted a great number of migratory birds, as well as three species of marine mammals. The marine area near Minjiang River Estuary is among the regions with the most abundant marine species in the world. It is also the region with the highest diversity of marine species at the same latitude in the northern hemisphere.

Taking fish as an example, 111 species of fish have been recorded in Minjiang River Estuary. By comparison, 94 species of fish have been recorded at Yangtze River Estuary (Chongming Dongtan Nature Reserve), located to the north of Minjiang River Estuary. Meanwhile, only 50 species and 65 species of fish have been recorded at Hong Kong Mai Po and Guangdong Zhanjiang Coast (Zhanjiang Mangrove Nature Reserve) respectively, which are located to the south of Minjiang River Estuary. The fish fauna of Minjiang River Estuary also has obvious characteristics of transition from north to south. For example, Ayu Plecoglossus altivelis, a representative species of typical catadroumous Salmonidae distributed along the coast of the Northwest Pacific Ocean, occurs here. Marbled Eel Anguilla marmorata, a catadromous fish widely occurring in tropical and subtropical coastal areas of the Pacific and Indian Ocean, can also be found here.

The benthic animals in Minjiang River Estuary and the surrounding marine water bodies are also rich in species diversity, including more than 20 species of mollusks. The large benthic clam Coelomactra antiquata is the most representative among them. This bivalve, endemic to the Northwest Pacific coast, is almost extinct from Japan and classified as a critically endangered in the country. Fortunately, Coelomactra antiquata still occurs in great number in Minjiang River Estuary. Thanks to the establishment of the Coelomactra antiquata Nature Reserve as early as in the 1980s, the offshore area of Minjiang River Estuary is where Coelomactra antiquata actually occur in the most concentrated density known to the world, and its quality as a seafood ingredient is also the best.

266 species of bird have been recorded in Minjiang River Estuary, while the recorded individuals of 10 waterbirds stably exceeds 1% of their global population according to surveys during 2017-2021. It is the northern edge of the wintering area of migratory birds such as Black-faced Spoonbill Platalea minor (EN) and Spoon-billed Sanpiper Calidris pygmeus (CR), and the southern edge of the summer habitat of Chinese Crested Tern Thalasseus bernsteini (CR), as well as the southern edge of the wintering area of wild geese and swans represented by Anser cygnoides and Cygnus columbianus. 3 species of cetaceans that appear in Minjiang River Estuary include Indo-pacific Hampback Dolphin Sousa chinensis and Finless Porpoise Neophocaena phocaenoides, which are mainly offshore residents, as well as Pseudo-Killer Whale Pseudorca crassidens, which migrates long distances across ocean. Abundant food resources allow these cetaceans to coexist in the Minjiang River Estuary.

Rich natural resources of Minjiang River Estuary have become an important material basis for coastal residents to live on. In the coastal areas of Southeast China, mountains and seas are adjacent to each other. In Fujian, there is no vast estuarine alluvial plains like the Yangtze River Delta and the Pearl River Delta, and the plains suitable for cultivation is extremely scarce. For this reason, coastal communities in Fujian, like Zhanggang at the Minjiang River Estuary, have been highly dependent on marine natural resources or trade through the ocean for their livelihoods for millennia. On the one hand, since the start of the agricultural civilization era, human beings have continued to reclaim and transform tidal flats to obtain land for farming and fishery, also exploit various biological resources from the ocean. On the other hand, people here have also developed a belief system that is full of reverence and awe for the ocean. The close interconnection between human beings and the ocean at both the material and spiritual level has profoundly affected people's lives and shaped the current landscape and seascape of Minjiang River Estuary.

Traditional rural communities around the Minjiang River Estuary are usually semi-agriculture and semi-fishery. Sustainable seasonal fish and clam harvesting is an important livelihood for them. Marine fisheries shape local dietary culture and folk custom. The sea-faring trade developed following the development of fishery has always been an important support for the economy of the communities around Minjiang River Estuary, too. Due to the long-term close relationship between the local people and the ocean, in the limited geographical space of the Minjiang River estuary, the gradation in landscape and seascape of "mountains - human settlements - plain farmland - seawater fish ponds - seawalls - intertidal mudflats - river port channels - open ocean surface" has been formed. The natural history of wild animals and plants represented by migratory birds and the busy human footprints are closely and orderly interwoven and coexist. Since the Eastern Han Dynasty more than 2,000 years ago, the port at the Minjiang River Estuary has been an important hub for the transshipment of goods from the south to the north along the coast of China. In the Ming Dynasty, the Shi-Po-Si(市舶司), Bureau for Foreign Shipping, had been moved from Quanzhou (the location of the world cultural heritage "Quanzhou: Emporium of the World in Song-Yuan China") to Fuzhou, which is located at Minjiang River Estuary. Zheng He's expedition fleet had to rest at the Minjiang River Estuary and wait for a favorable monsoon before each departure. In the middle and late 19th century, the Minjiang River Estuary became one of the important birthplaces of the modern shipbuilding industry along the coast of China. Since the late 1970s, the modernization and industrialization of China's coastal areas has accelerated, and the natural habitats on the coastline have been rapidly converted. However, the Coelomactra antiquata Nature Reserve has been established since the 1980s. At the beginning of this century, the local government recognized the importance of the wetlands of Minjiang River Estuary in conservation, and farsightedly designated the area with the highest concentration of wild animals in the Minjiang River Estuary as a nature reserve. At present, a series of protected areas, e.g. the wetland park, 2 nature reserves, and Coelomactra antiquata Nature Reserve etc., have formed a conservation networks to protect the intertidal zone and near offshores as a whole. These actions have realized the overall protection of the coastal area and offshore waters. The protection of the Minjiang River Estuary is the forerunner of China's vigorous efforts to promote nature conservation in the most developed and densely populated coastal areas after 2017, and early practice on "ecological civilization", which gives consideration to economic development and ecological governance.

In today's Minjiang River Estuary, we can witness that the mountain and sea are filled with vitality, as well as the livelihood of local people in continuous evolution for millennia. We can also learn from the historical experience that the relationship between human beings and the sea has been transferred from exploitation to protection, and from confrontation to harmony. The landscape and seascape of Minjiang River Estuary provides a sanctuary for some of the most endangered species in the world, and demonstrates the possibility for humans to think about how to well treat the oceans in today's increasingly crowded planet.

Justification of Outstanding Universal Value

Criterion (x): Minjiang River Estuary is located at the ecotone between South China Rainforest in the Oriental Realm and China Subtropical Forest in the Palaearctic realm on the coast of the Asian continent. Its offshore area is the ecotone between Warm Temperate Northwest Pacific and South China Sea. The special geographical location and the marine and terrestrial ecological processes linked by the Minjiang River have created a full range of unique wetlands and offshore habitats, which offers a key shelter for some of the world's most endangered species. Minjiang River Estuary is recognized as an Important Bird Area (IBA, No. CN411) and a Key Biodiversity Area (KBA). It is also designated as the most important and largest IBA in the coastal areas from East Asia to Southeast Asia, to the south of the Yellow Sea Ecological Area. The offshore area of Minjiang River Estuary is located in the marine area with the most abundant marine biodiversity in the global temperate coastal waters.

Minjiang River Estuary is rich in biodiversity. The biota shows obvious features of transition from south to north. A total of 14 formations of three vegetation types, including mangroves, coastal salt marshes, and coastal sandy vegetation, are distributed between the land and the sea. The salt marsh vegetation, which is a mixture of Scirpus mariqueter, mangroves and reeds, is a unique vegetation type on this section of the coast where Minjiang River Estuary lies right in the center. Among them, reeds and Scirpus mariqueter reflect the characteristics of coastal salt marsh vegetation in East Asia temperate region, while mangrove reflects the characteristics of coastal salt marsh vegetation in subtropical and tropical region.

Minjiang River Estuary supports 395 species of wild vertebrates, including 7 species of mammals belonging to 5 families and 3 orders; 266 species of birds belonging to 53 families and 19 orders; 152 species of waterbirds belonging to 24 families and 9 orders; 8 species of reptiles belonging to 4 families and 2 orders; 3 species of amphibians belonging to 2 families and 1 order; 111 species of fish belonging to 47 families and 16 orders; and 553 species of other aquatic organisms. In general, Minjiang River Estuary provides a good habitat for many water birds, marine mammals, reptiles, fish, crustaceans and mollusks. The rare and endangered waterbirds are the most attractive attributes of the biodiversity of Minjiang River Estuary.

In different seasons of the year, a large number of waterfowls, shorebirds, gulls, herons and other waterbirds inhabit the wetlands of Minjiang River Estuary. More than 50,000 waterbirds are perennially distributed and overwintered in Minjiang River Estuary. According to monitoring data from 2017 to 2021, 10 waterbirds such as Chinese Crested Tern, Spoon-billed Sandpiper, and Black-faced Spoonbill that live in the wetlands of Minjiang River Estuary and offshore areas all year round exceeds 1% of the global population, meeting the criteria of a Ramsar site. The coastal waters of Minjiang River Estuary are important breeding areas for many tern species, including Chinese Crested Tern, which is listed as the critically endangered species. According to the monitoring of experts in recent years, there are no more than 150 mature individuals of Chinese Crested Tern in the world, and the highest record in Minjiang River Estuary has reached 16 individuals. This species spends the whole summer here, while courtship, mating and foraging behaviors have been recorded. Besides, young fledglings will be brought to Minjiang River Estuary for a while by their parents, annually. Minjiang River Estuary is also the northernmost known wintering ground for Spoon-billed Sandpiper, another critically endangered species. In addition, 19 other species of threatened birds on the IUCN Red List use Minjiang River Estuary as their seasonal habitat. These species include Swan Goose, which is listed as the vulnerable species. In recent decades, Minjiang River Estuary has maintained the largest wintering population of Swan Goose outside the middle and lower reaches of the Yangtze River. It is extremely important for the conservation of the genetic diversity of this species.

Abundant marine life feeds and reproduces between estuarine wetlands and the ocean. Because of the transition of marine ecoregions, the number of fish species in the coastal waters of Minjiang River Estuary is significantly higher than that in other coastal natural protected areas located further north or south. The number of recorded fish species is as high as 111. The species and biomass of zooplankton and benthos here are also quite abundant. This area is the most important distribution range of Coelomactra antiquata, a bivalve species endemic to the northwest Pacific. All sea turtle species recorded along the East Asian coast occur here, too. Three species of cetaceans are found in this area, including Sousa chinensis and Neophocaena phocaenoides, which inhabit offshore, as well as Pseudorca crassidens, which migrates in long distance in the ocean.

Rich marine biological resources are also an important material basis for the survival and development of surrounding communities. For thousands of years, the Minjiang River Estuary has been a home for human beings to live and work in peace and contentment. With controlled seasonal harvesting, today, the abundant clam and marine fish resources are still an important source of living materials and economic income for the communities around the Minjiang River Estuary. Minjiang River Estuary was also an important starting point for the Chinese people to move from the coast to the ocean in both ancient and modern times. Fishery and sea-faring trade have enabled the people here to establish a close connection with the ocean both materially and spiritually, and have developed a belief system that reveres the power of the ocean. On this basis, numerous wildlife and bustling human economic activities have been able to coexist at Minjiang River Estuary, and a series of wetland and marine protected areas have been established, forming a successful practice of modern ecological protection in China's coastal areas.

The sustainable resource utilization methods and traditional beliefs of the communities around Minjiang River Estuary, together with the modern protected area governance system, ensure that this area can continue to provide living conditions for wildlife and humans, while offering a global demonstrative case for the protection and management of marine and terrestrial ecosystems in densely populated areas.

Statements of authenticity and/or integrity

The nominated property includes typical marine and land landform units, vegetation types, and rare and endangered species’ habitats that have outstanding universal values (OUV), as well as their relationship with local traditional land and marine use and management. The nominated property is complete in terms of OUV attributes, scope and values.

The nominated property involves four natural protected areas, namely: 1. Fujian Changle Minjiang River Estuary National Wetland Park (hereinafter referred to as the "Wetland Park"); 2. Fujian Minjiang River Estuary Wetland National Nature Reserve (hereinafter referred to as the "NNR"); 3. Fujian Mawei Minjiang River Estuary Wetland Provincial Nature Reserve (hereinafter referred to as the "PNR") and 4. Fujian Changle Coelomactra antiquata Resource Breeding Nature Reserve (hereinafter referred to as " Coelomactra antiquata NR"). The boundaries of the above four natural protected areas are inter-connected, covering the spectrum of landscape and seascape composed of various typical habitats from the land area, wetlands to the offshore 10-meter isobath sea area of Minjiang River Estuary. It consists of the feeding grounds and high tide habitats of rare and endangered birds such as Swan Goose, Tundra Swan, Chinese Crested Tern, Spoon-billed Sandpiper, and Black-faced Spoonbill; the main feeding and migratory areas of marine mammals and sea turtles in the offshore, as well as the main breeding, feeding and migration places of various fish and benthos in Minjiang River Estuary.

The Wetland Park which is located on the southern bank of the Minjiang River Estuary, is an area on the land side of Minjiang River Estuary shared by human beings and wild birds. At the same time, the Wetland Park is also a buffering area between the natural habitat and the cultivated areas on the land side. Wetland Park is the main distribution area of reed, Cyperus malaccensis and mangrove vegetation. The National Nature Reserve (NNR), located to the north and east parts of the Wetland Park, is the main distribution area of the salt marsh vegetation of Scirpus mariqueter and the intertidal mudflat, and also the main foraging area for various waterbirds where the most abundant benthic animals occur. The PNR and Coelomactra antiquata NR surround the NNR from the north, east and south. These sea areas are also feeding areas for concentrated seabirds such as Chinese Crested Terns, and are also the provenances for the delivery of benthic animals and fish seedlings to NNR and Wetland Park. The organisms that spread out or migrate into the estuarine wetlands become the food source for a large number of birds and other predatory organisms in the estuary area, and drive the matter circulation between the offshore and coastal wetlands, and even the offshore and terrestrial ecosystems. At the same time, the PNR and Coelomactra antiquata NR also buffer the NNR with the highest concentration of internationally threatened birds from the surrounding busy shipping lanes, and leave a safe space for offshore cetaceans.

The core area of the Wetland Park, NNR and PNR are under the strictest protection. Natural and artificial wetlands, intertidal flats and shallow seas have all been included in the ecological red line, and all kinds of resource exploitation activities are prohibited in them. The Coelomactra antiquata NR is located to the east and south of the two nature reserves and is connected to them. The Coelomactra antiquata NR is vast and covering the shallow sea in the east and a large area of offshore water in the south of Minjiang River Estuary. Fishing and other human activities are under strict restrictions within the Coelomactra antiquata NR. Marine life such as fish and benthic animals migrate or move periodically between the Coelomactra antiquata NR and other NRs as well as the wetland park. Those protected areas integrate a full spectrum of habitats which supports the life-cycle of these species.

These four nature reserves are adjacent to each other, forming a complete protection network of the biodiversity as well as the diverse and unique habitat system of Minjiang River Estuary. The typical habitat, as well as the rare and endangered endemic species in the nominated property, which are strictly protected by relevant Chinese laws, are in good condition. Therefore, the integrity of OUVs in the nominated property are in good condition. Protection and management plans have been prepared and implemented in each natural protected area, and functional zoning management has also been carried out to ensure that surrounding communities can sustainably maintain traditional natural resource utilization in specific section within each protected area.

In addition, as a key site in the East Asian-Australasia Flyway (the EAAF), Minjiang River Estuary is located between the Yellow Sea Ecoregion and a series of important migratory bird habitats from the coast of South China to Australia and New Zealand. Spoon-billed Sandpiper, Black-faced Spoonbill and other endangered birds stay here seasonally, before or after crossing the Yellow Sea Ecoregion. In the future, if Minjiang River Estuary can be enlisted in the World Heritage network of the EAAF, the integrity of the biodiversity conservation network at the flyway scale can also be enhanced.

Comparison with other similar properties

From the perspective of terrestrial Biogeographic regionalization, there are a number of natural or cultural and natural world heritages in the South China Rainforest Province and the Central China Subtropical Forest Province, in which Minjiang River Estuary is involved. However, in South China Rainforest Province, there is only one coastal World Natural Heritage, which is Ha Long Bay, Vietnam. Then, there is only one coastal World Heritage tentative project (mixed), Haitan, which is also located in Fujian and adjacent to Minjiang River Estuary. Ha Long Bay is listed on the World Heritage List with its outstanding maritime karst landforms and relevant biodiversity. Haitan is famous for its insular landform of natural beauty. There is neither world natural heritage site nor tentative list project located in coastal areas of Central China's Subtropical Forest Province.

From the perspective of the ecotone between the Palearctic Realm and the Oriental Realm, there are numerous natural or cultural and natural world heritage projects, i.e Protected Areas of Three Parallel Rivers in Yunnan, and Wuyi Mountains in Fujian, China; Islands and forests in Kagoshima and Okinawa, and Yakushima, Japan. All these sites are of OUVs on biodiversity or ecosystems. However, no or few attributes related to seas and oceans are involved in these sites.

From the perspective of marine biogeographic regionalization, there is only one world natural heritage site in the South China Sea region in which Minjiang River Estuary is involved, namely Ha Long Bay. As mentioned earlier, the OUVs of Ha Long Bay does not include marine biodiversity and habitat. On the other hand, Warm Temperate Northwest Pacific region in which Minjiang River Estuary is involved is a gap for natural World Heritage.

Minjiang River Estuary is located in the EAAF. There are several World Natural Heritage or tentative list projects with migratory bird habitats as OUV attributes in this flyway. But only Migratory Bird Sanctuaries along the Coast of Yellow Sea-Bohai Gulf of China (Phase I) heritage sites and (Phase II) nominated sites located in the Yellow Sea ecoregion and Getbol Korean Tidal Flats located in South Korea are close to Minjiang River Estuary, which are supporting some of the most endangered waterbirds like Black-faced Spoonbill, Spoon-billed Sandpiper and Chinese Crested Tern. But Minjiang River Estuary, Migratory Bird Sanctuaries along the Coast of Yellow Sea-Bohai Gulf of China and Korean Tidal Flats are located in different marine biogeographic regions. Migratory Bird Sanctuaries along the Coast of Yellow Sea-Bohai Gulf of China and Korean Tidal Flats are located in the Yellow Sea ecoregions, while Minjiang River Estuary located in the ecotone between South China Sea and Warm Temperate Northwest Pacific. The differences between ecoregions result unique mixed salt marsh vegetation of reed, mangrove and Scirpus mariqueter as well as intertidal benthic faunal community in Minjiang River Estuary. The two heritage sites and the associated series of nominated intertidal mudflats in the Yellow Sea Ecoregion are characterized by mixed salt marsh vegetation of Suaeda glauca, Aeluropus sinensis and reeds and corresponding intertidal benthic faunal communities.

From the perspective of residential status and composition of migratory birds, the Minjiang River Estuary Wetland is also different from the wetlands in the Yellow Sea Ecoregion and the adjacent South China Sea Ecoregion. For example, Black-faced Spoonbills (A few individuals also stay during summer in recent years.) and Spoon-billed Sandpipers winter in Minjiang River Estuary. In other important coastal bird habitats in the Yellow Sea Ecoregion, they are mainly summer breeders or seasonal vistors, respectively. Chinese crested tern, which occurs at Minjiang River Estuary during the breeding season, is a rare seasonal visitor in the important bird habitat along the coast of the South China Sea Ecoregion. Compared with the important bird habitats in the Yellow Sea Ecoregion, there are more shorebirds in winter and more terns in summer at Minjiang River Estuary. Compared with other important bird habitats along the coast of the South China Sea Ecoregion, Minjiang River Estuary is the only place where a large number of geese and swans stably overwinter.

The south-north transition in biogeographic regions makes the Minjiang River Estuary wetlands a unique habitat for migratory birds in East Asia, even in the EAAF and the global scale, supporting the survival of many threatened species of global significance.

To sum up, the Minjiang River Estuary wetland has a unique geographical location, which is the ecotone of two terrestrial biogeographic regions and two marine biogeographical regions. The ecological and biological processes between the sea and the land are driven by the unique geological and hydrological processes of the Minjiang River, forming a unique refuge for endangered species in the world.