Asian Coastal Wetlands

Occasional Paper #47

In 2011, the IUCN Species Survival Commission and IUCN Asia Regional Office commissioned an independent report to assess the state and condition of intertidal habitats along the East Asian-Australasian Flyway (EAAF), in response to growing concerns expressed by IUCN members over observed declines in biodiversity, the loss of ecological services, and an increase in ecological disasters. The report is a situation analysis, and it seeks to gather in one place the relevant data and analyses, and to present as clear a picture of the status of the intertidal zone in the EAAF as the data allow. By intention, the resulting report makes no recommendations, but it should serve as a resource for those stakeholders empowered to make or influence decisions and policies in the region.

Revised version

The report shows that fisheries and vital ecological services are collapsing and ecological disasters increasing, with resulting impacts on human livelihoods. Migratory waterbird species along the flyway are showing exceptionally rapid declines. These declines are linked mainly to the disappearance and degradation of migratory staging posts, rather than problems on the breeding or wintering grounds.

The report identified 16 key areas along the flyway (from an analysis of 388 East Asian flyway sites with tidal flats used by waterbirds of the EAAF), with six of these in the Yellow Sea (including the Bohai Sea). Here, the most pressing threat is the fast pace of coastal land reclamation (defined as conversion of natural wetland into dry land and artificial wetland by mechanical means). Remote sensing and geographical information system (GIS) analyses show mean losses of 35% of intertidal habitat area across the six key areas of the Yellow Sea since the early 1980s. Losses of such magnitude are likely the key drivers of declines in biodiversity and ecosystem services in the intertidal zone of the region.

As well as these critical areas, many other sites are used by particular species as they move north or south on migration, or throughout the non-breeding season, and also need protection as part of a critical site network.

Waterbirds of the East Asian Flyway coastal wetlands are facing extinction

Waterbirds that depend on the Asian intertidal habitats of the East Asian-Australasian Flyway (EAAF) during their non-breeding season are the world’s most threatened migratory birds, apart from albatrosses and petrels.

At least 24 such species are heading towards extinction, with many others facing exceptionally rapid losses of 5–9 % per year. With declines of 26 % per year the Spoon-billed Sandpiper could be extinct within a decade. These rates of species population decline are among the highest of any ecological system on the planet.

Rapid land reclamation of Asian tidal flats is driving many waterbirds towards extinction

Overall, East Asian intertidal habitats (including beaches, marshes, mudflats, mangroves and seagrass beds) are being lost at a rate unprecedented for the coastal zone elsewhere in the world. Some countries have lost more than half of their coastal wetland area to land reclamation since 1980. These rates of habitat loss are comparable to those of tropical rainforests and mangroves.

Evidence suggests that these reclamations, especially in the crucial staging area of the Yellow Sea (including the Bohai Sea), are driving the waterbird declines and related environmental problems. Breeding success in the Arctic and survival in the Australasian sites where the birds spend the northern winter appear to be adequate; the main problems seem to be in the East Asian staging areas.

In this most densely populated part of the world, the effects of reclamation act cumulatively with other threats to the ecology of the Asian intertidal zone system. These threats include pollution, non-native species, silt flow reduction resulting from damming of major rivers, over-fishing, unsustainable hunting of waterbirds, and conversion of mudflats for aquaculture or other uses, plus the added challenges of climate change, such as increased risk of floods.

Waterbirds indicate deterioration in Asian coastal ecosystems and their services

The declines in waterbird populations are signals of wider deterioration in the quality of intertidal ecosystems. Healthy tidal flats provide many services of direct economic benefit to the lives and livelihoods of millions of people in local communities and beyond.

Such services include fisheries worth billions of US$ per year and coast defences, which if lost expose coastal cities, towns and lands to economically devastating damage.

Marine mammals, fish, invertebrates and plants associated with tidal ecosystems are also in sharp decline and areas of the Yellow and Bohai Seas are becoming ‘dead’ seas. Meanwhile there has been a significant increase in ecological disasters including floods, salination of coastal areas, outbreaks of harmful algal blooms, and death of fish and mariculture stocks.

International co-operation, and effective environmental safeguards, are needed

The birds and habitats of the EAAF are the shared natural heritage of 22 countries. At present, each country’s economic and environmental sustainability is being damaged by the actions of its neighbours. International cooperation is required to secure the region’s tidal ecosystem resources in the long term.

A healthy environment is essential for sustainable development. This means that rapid economic growth must build in effective environmental safeguards. Otherwise, economic gains may be short-lived – being undermined by the loss of valuable ecosystem services and costly ecological disasters.