ANOTHER LIFE: In a world just now convulsed by the big and the violent, the tiny snails called Vertigo seem dizzyingly insignificant. Their lives are spent in totally peaceful obscurity, down at the damp roots of grasses and moss, writes Michael Viney.
They graze on bacteria and microalgae, part of the vast but diminishing army of invertebrates that recycles vegetation into the soil. These snails creep along beneath shells rather smaller than a grain of rice and spun into vertical whorls, a giddy shape that prompts their scientific name.
Some 15 Vertigo species have survived in Europe since the Ice Age, eight of them in Ireland alone. The kind we had down on the duach until lately was Vertigo angustior, a name of fine Roman resonance for a creature with a shell less than two millimetres long. This shared the dunes and their damp, mossy lawns with sheep - more and more sheep, decade by decade, until the peak of the 1990s. The Vertigo angustior's special corners were trampled by sharp little feet and smothered with sheep dung, and the last of the snails, for all we know, was munched up in a tuft of grass.
A few summers ago, Evelyn Moorkens, the Dúchas specialist in molluscs, searched the likely moist places on her knees, with a magnifying glass, and found more than 50 kinds of mollusc shell - but no Vertigo angustior. Her search was part of a wider European scrutiny of the Vertigo family that has followed the edict of the EU Habitats Directive, now 10 years old, that four of the snails were growing dangerously rare and must be given protection. In the interim, the snails have found themselves at the heart of major conservation planning rows, their near invisibility prompting the usual incomprehension and derision from those on the side of development.
In Britain, the notorious Newbury bypass threatened Vertigo moulinsiana, the largest UK species (at 2.7 millimetres), and a special marsh was created nearby for its successful relocation. In Ireland, the fortunes of Vertigo geyeri, an Arctic survivor in our glacially littered lowlands, created problems for planning a motorway which threatened to drain Pollardstown Fen in Co Kildare. In our coastal dune systems, populations of Vertigo angustior are named in 13 proposed Special Areas of Conservation, including the one controversially reshaped to accommodate the new championship golf course at Doughmore, Co Clare.
The diminutive size and limited fan club of the Vertigo snails has created special conservation problems for scientists as well. Last April, Dúchas hosted a three day seminar for European Vertigo specialists, and a report of some 180 pages has just been published by Heldia, the leading German journal of the study of molluscs.
It was organised by Evelyn Moorkens and Martin Speight (who leads Dúchas research on invertebrates) and their introduction to the report is candid about one seeming difficulty: "Detractors would argue that the apparent rarity of these species reflects more the scarcity of conchologists capable of identifying them and interested in searching for them, than the actual status of the snails."
The workshop, reporting on intensive field studies, came up with some unexpected findings. Yes, there are many more populations of Vertigo snails than were known about before. But, if anything, more of their species are threatened than the four named in the directive. And the difficulties of monitoring and protecting them are huge.
In the Republic, for example, the "lowland" species, Vertigo geyeri, has been discovered in unexpected corners of the limestone uplands of Co Leitrim. They were sieved from the base of hedges growing in spring-fed hillside flushes grazed by sheep. They were often in patches of less than one metre square - typical of micro-habitats that get lost in the broad "wetland" categories of the Habitats Directive.
Sometimes, the snails don't stay in one place but move their base according to the weather. Their numbers can also fluctuate enormously according to time of year, climatic conditions and the reproductive cycle.
At Doughmore Bay, Co Clare, Evelyn Moorkens hand-searched every likely place in 153 hectares of dunes and washed samples of vegetation into sieves right down to half- millimetre mesh. This yielded the first records of Vertigo angustior, grazing through the damp, feathery mosses at the grass roots in areas that had escaped intensive stocking with sheep or cattle.
Her population estimates for Doughmore have seemed both huge and enormously variable: 10 million snails in 1999, 21.5 million in 2001. It will need years of intensive fieldwork to make full sense of such fluctuations and decide just what measures will guarantee the "favourable conservation status" sought by the Habitats Directive.
In the meantime, Vertigo will continue to test how serious we are about saving every species we can, even those we need a pocket-lens to see.