Another Life: A few years ago, in a marshy limestone valley in north Yorkshire, forestry workers set about pulling out almost 1,000 Sitka spruce, planted there some 20 years before.
They were creating a four-acre nature reserve for Vertigo geyeri, an infinitesimal Arctic snail that had survived there since the post-glacial tundra. It was found accidentally in 1994 in a naturalist's vegetation sample and - as far as I know - has never been seen there since. Indeed, until one was found on a Cumbrian fell in 1960, it was thought this snail, half the size of a grain of rice, occurred in Britain only as a fossil.
The Yorkshire project followed the much earlier, notorious and costly furore over Britain's Newbury bypass. This led, as one result, to the creation of a special marsh to which numbers of another rare species - Vertigo moulinsiana, all of 2.7 millimetres long - were moved successfully.
Alone in Europe, Ireland not only has a third rare species, Vertigo angustior, but finds itself with all three snails, listed for protection by the EU Habitats Directive, living in the same vulnerable location. Thanks to the new Kildare by-pass, opened late in 2003, their home at the margin of Pollardstown Fen is now at serious risk of a crucial loss of water. The fen levels are falling, despite the "tanking" of some three kilometres of road at the cost of an extra €6 million. A new consultants' report for Kildare County Council warns that a "mitigation remedial plan" may soon need to be put into effect.
The costly sealing of the cutting with an impermeable membrane was not primarily to protect the snails, but also a rare habitat. They live at the raised margin of a 10,000-year-old fen covered with tall Cladium reeds and kept wet by lime-rich, hard-water springs that produce slabs of tufa, a porous, calcareous rock.
Along with its teeming wildlife (otters, wetland birds and rare moths) such a habitat is now rare in Europe and protected within the Natura network under several different categories. The Curragh aquifer that feeds its springs also happens to serve the famous Japanese Gardens and part of the Grand Canal.
Plans for the bypass were approved by the minister for the environment in 1996 without any assessment of its likely impact on the adjoining fen, an error that has cost dearly in time, money and controversy. The eventual idea of holding in the water with a membrane was borrowed from Dutch experience in a very different geology. Early optimism about its effectiveness began to shift soon after the road was opened, as water levels in the fen began to fall. Droughts in 2003 and 2004 helped to produce what Terrascope Environmental Consultants now assesses as "serious ecological risk to critical fen habitats".
In all this, Vertigo geyeri has served as the "miner's canary" not only because of its greater rarity but because it depends specifically on a habitat of calcareous springs and the moist mosses and sedges that grow around them. It was singled out for monitoring at its most precarious stations, and concern has grown this winter as water levels seem likely to remain perilously low.
The report on the updated"mitigation remedial plan" is huge and no doubt costly - two highly-expert volumes totalling 320 pages. Its size reflects the problems of interfering with such a complex natural ecosystem. Almost any "remedy" carries risks of making things worse and every option gets its feasibility and risk assessment - even to the excavation of new springs.
As an urgent measure, irrigating the fen's surface is the first choice, along with blocking some springs to raise others and transferring two of the snails - Vertigo moulinsiana and Vertigo angustior - temporarily, along with big turves of their plant habitat. Every suitable spot in the fen already has its snails, and creating a permanent fresh habitat with the right kind of plants could take years.
Vertigo geyeri, however, the rare and most vulnerable star of the three, is not for moving at all. Collecting its fragile, near-invisible individuals is hugely difficult, as is maintaining the right kind of humidity in a captive microclimate. Some losses are looking inevitable - much, no doubt, to Europe's great displeasure.
However it turns out, the Pollardstown saga seems likely to prove a classic case-study in conservation management and its political, economic and ecological problems. It should be an awful warning - as if any were now needed - against wilful ministerial decisions about roads.
And while Kildare County Council now has to take "remedial" decisions, it is in for a taxing journey through Terrascope's painstaking labyrinth of risks and doubts.
Eye On Nature returns next week