Nature Studies by Michael McCarthy: Precious estuaries we must protect

In the ugly litany of environmental crimes, perhaps the worst is the destruction of a whole ecosystem. In its sweeping finality it's like the sacking of a city. Troy resonates with us still, as does Hiroshima; so, one day, may lost forests.

Deforestation is the most obvious example of whole-ecosystem ruin, but there are many others. A particularly egregious one is mountaintop-removal. This is the scarcely-believable practice, undertaken by American coal-mining companies in areas such as West Virginia, of slicing the top off forested hills, as if you were cutting the top off a pineapple, and dumping the debris in the valley below (the purpose being easy access to the coal seams thus exposed). Besides the great weal on the landscape that this leaves, the ecological consequences are horrendous, and mountaintop-removal is thought to be greatly helping the slide towards extinction of one of America's most appealing songbirds, the cerulean warbler.

There are many examples closer to home: the cutting down of a woodland, the ploughing-up of chalk downs, the obliteration of a lowland heath. When I was a boy, there was one ecosystem destruction I feared especially, and that was the end of an estuary.

Estuaries are the poor relations of the landscape, not remotely figuring in popular culture. Know any estuary songs? No. This lack of appreciation may stem from the fact that the mouths of rivers are seen as neither the one thing nor the other, yet the mingling of two worlds, as the flowing water meets the sea, always produces ecological riches, and often surroundings which are inspiring.

So it was with me, doing my boyhood birdwatching in the estuary of the River Dee between what was then Cheshire (now Merseyside) and North Wales. The Dee Estuary is more than five miles across, so big you could walk out into the marshes and sing at the top of your voice and there was no one listening to think you were a nutter.

It was a wonderful wild and lonely landscape, animated by the haunting cries of the wading birds, the redshanks and the greenshanks, and I always feared it would be lost because sooner or later some bright spark would decide to build a barrage across it, topped with a motorway from Liverpool to Holyhead, and what was behind the barrage would be "reclaimed", to use that word developers use, when the real meaning is "destroyed".

It didn't happen. The fast road to Wales was built, but thank God, upstream of the estuary and the marshes were untouched, and eventually given protection by the European Union (and by the RSPB), for their birdlife. For the Dee wasn't just rich in resident birds; its salt marshes and mudflats made it a vital wintering and stopover site for thousands of migrants, especially the waders which fly up to breed in the Arctic, such as dunlin and knot, and fly back south for the winter. All Britain's big estuaries, in fact, are used as stopping places on the Western European Flyway, the great avian migratory route along the edge of Europe, from Africa to the Arctic and back.

But here's a thing. On the other side of the world is another such route: the East Asian Flyway. This is used by wading birds that breed in Siberia and winter 5,000 miles away in south-east Asia, and what was perhaps the most important bird stopover site on the whole length of it, the Saemangeum estuary, on the Yellow Sea coast of South Korea, has just been destroyed.

Saemangeum is probably the biggest estuary obliteration that has ever happened on earth, facilitated by the building of the world's longest sea wall, more than 21 miles from end to end; it has replaced a coastline of more than 60 miles holding a vast area of tidal flats used by an estimated 400,000 waders on their annual odysseys. The tidal flats behind the wall have been "reclaimed"; they are drying out now and will be turned into agricultural land; and 400,000 migrants have lost their pitstop.

An immediate consequence of this is that one of the world's most charming birds, the spoonbilled sandpiper, has been pushed to the edge of extinction. This is a wader whose spatulate bill gives it a slightly comical look, and the consequent endearing appeal of a puffin; it breeds in the Russian Far East and winters in places like India and Burma. The loss of its Saemangeum stopover appears to have been the last straw, more or less, for a population which was already rapidly declining, and there are thought to be fewer than 200 birds left in existence.

A desperate rescue operation to save the spoonbilled sandpiper is going on, right now, in which Britain's Wildfowl and Wetlands Trust (along with Birds Russia) is playing a vital role; eggs have been taken from some of the remaining Siberian nests to start a captive breeding population, and this week, the first chicks hatched out, 18 of them no less; eventually they will end up at the WWT headquarters at Slimbridge in Gloucestershire.

Tremendous news for any bird lover; I can't get enough of spoonbilled sandpiper pictures. But then I find myself drawn to another picture, this one on Google Maps, of Saemangeum itself; click on the satellite button and there is the sea wall, the bright ribbon of concrete in a blue sea, photographed from space, and behind it, the estuary which has gone.

No one seems bothered. It's a shining example of Asian economic development, and there are no songs about mudflats, no poems, are there? Nobody weeps for lost estuaries. But I think of my boyhood on the Dee, and I look at it with a very heavy heart.

m.mccarthy@independent.co.uk; twitter.com/@mjpmccarthy