The money or the snails
A rare and endangered native species was removed so more coal could be extracted from under a West Coast mountain. The mining company went broke. The creature it displaced lives on in a strange purgatory.
The last stronghold of a critically rare species is not its original home, high on the peaks of the South Island’s West Coast. It’s somewhere much stranger: two large fridges, a few strides apart, in a car park in Hokitika.
It has been a long, unusual journey for a species one threat ranking below extinction and found only in New Zealand.
For millions of years it had evolved alongside its mountain home, becoming intractable from the landscape, until a valuable coal seam was discovered beneath it.
By the time the species was formally described, its habitat was already gone – the report announcing it as a new species described its habitat, unusually, in the past tense.
For more than a decade, a sizeable population of Powelliphanta augusta – a giant, carnivorous snail – has lived in plastic containers, neatly stacked in industrial-sized coldstores on the West Coast.
Each snail is fed between four and six worms every month, depending on their size. They are regularly weighed and monitored, years of measurements detailed in handwritten notes packed in thick binders. They are tracked by tiny labels on their shells.
The snails are there because there is nowhere else for them to go. Their original habitat was unique – a brutal combination of wet, windy, acidic, and cloudy – and cannot be precisely replicated elsewhere.
The Department of Conservation (DOC) was tasked with looking after the species in captivity after they were moved. It was supposed to end after a decade, but it did not – it has now fallen to the taxpayer to keep the species alive.
Without the fridges and the DOC staff caring for them, the snails would be extinct. But their miraculous survival is a reminder of the fact they were sacrificed. P. augusta had been accidentally discovered long before it was formally described. The first signs were uncovered in 1996, by a group of botanists from Nelson who were roaming the Stockton plateau. They came across six large shells, each with a handsome walnut coat, swirled in a koru-like pattern.
When the botanists returned to Nelson, carrying the shells in a bag, they took them to the local DOC office. They were given to Kath Walker, DOC’S snail expert.
At the time, only one snail species was known to live in such a hostile location: Powelliphanta patrickensis, one of New Zealand’s giant, carnivorous Powelliphanta species.
Walker didn’t think much of it. Based on the described location and a cursory scan of the shells’ appearance, she reasonably assumed they were P. patrickensis. They were stored with other P. patrickensis shells and promptly forgotten.
About the same time, the state-owned coal miner Solid Energy was planning to expand. A decade earlier it had secured a coal-mining licence for the Stockton plateau, which would soon become the largest opencast coalmine in New Zealand.
As its footprint on the plateau grew, and its output doubled then doubled again, Solid Energy struck a problem. It was running out of its most valuable coal.
Most of the coal in New Zealand is low-quality, but there are small pockets of high-quality coal, sometimes called ‘‘the caviar of coal’’. By blending the two types together, the result is a product highly sought after for steel manufacturing.
In search of this high-quality coal, Solid Energy was pushing against the boundaries of its licence area, into new ground bordering conservation land.
It was planning to mine an area locals called the Happy Valley, a drenched, forested valley home to kiwi and a population of P. patrickensis, among other rare flora and fauna
species. Solid Energy’s plan was vigorously opposed by environmentalists. A group calling itself Save Happy Valley fought the mine’s expansion, which ended up in the courts. As part of the court proceedings, expert witnesses were asked to give advice. Among them was Kath Walker, who was asked to provide information about P. patrickensis.
She sorted through the shells in the Nelson office and closely examined the ones handed to her nearly a decade earlier. She noticed the subtle differences; the less glossy shell, the narrow red bands. She realised it was another species entirely.
Walker rushed to track down the botanists who had found the shells nearly a decade earlier. They gave her a precise location for the shells, an escarpment near Mt Augustus.
When Walker arrived there in early 2005, she found a large hole in the ground. The only known habitat of this new species had become a mine. ‘‘They [P. augusta] were probably extensive over that northeastern end of Stockton plateau,’’ Walker says. ‘‘It was down to maybe 5 per cent, 2 per cent. Not much was left.’’
There was, however, one stroke of luck. Due to the way the border was drawn on the mine’s licence, a small area marking the lowest point of the ridgeline was technically within the conservation estate, and off limits for mining. There was a snail population there. Walker inferred there would be more within the mine site, which proved to be the case.
Today, that tiny area of natural habitat is known as the DOC triangle, and it is the last
remaining scrap of natural habitat, a crumbly island in what used to be a vast continent.
For a few years after the snails were moved into captivity, they lived in relative luxury. Some were kept on stainless steel trays, in specially built environmental chambers that could regulate light and temperature and simulate rain.
The programme was being paid for by Solid Energy, as a condition of its wildlife permit. The company spent an estimated $7m on it over the decade, not including the cost of relocating the snails in the first place.
Not long after its responsibility for the snails lapsed, Solid Energy hit financial strife. It dragged the environmental chambers from the DOC office and sold them at auction in Christchurch.
Today’s set-up is humble, but comfortable. White icecream containers house the oldest snails, sort of like a retirement unit. The larger Sistema plastic containers – the same ones you’d buy at the supermarket – each have three second-generation snails which have reached adulthood, and the smallest containers have the littlest snails, which take around eight years to reach full size.
‘‘In here they’ve got a pretty easy life,’’ says DOC ranger Rodney Phillips, who runs the programme. ‘‘They have a constant temperature, constant light cycle, constant food. It’s a pretty stable environment for them.’’
The actions of the DOC staff running the programme almost certainly saved the species from extinction. The total snail population has grown in captivity, and is nearing capacity.
There are about 1400 snails in the fridges, requiring nearly 10,000 worms each month.
After the snails were moved, there was such a worm shortage that DOC staff were sorting through cow pats, looking for every worm they could find. Now they’ve got a large compost bin, fed with horse manure and food scraps from DOC staff.
The captive programme costs around $50,000 a year, which is paid for by taxpayers.
It took a long time to make the programme as successful as it has become. Before the P.
augusta were put into fridges, there had been no large-scale captive programme for Powelliphanta. They were a deeply mysterious genus, doing whoknows-what in remote bush of the South Island’s western flank.
Because of the captive programme, one of our most recently discovered snail species is also the one we know the most about.
They are hermaphrodites which both lay and fertilise eggs. Their eggs are tiny, pink orbs, a bit like delicate bird eggs, which take on average 200 days to hatch but sometimes 1000 days.
We know that sharp changes in light can induce the snails to breed. They still lay their eggs in spring, even though conditions in the fridges are the same year round. Even the snails that have never known a world with seasons are ruled by that biological truth.
Despite a famously slow gait, New Zealand’s native snails strike their prey like snakes, snapping on to a worm and sucking it up like spaghetti.
The intent had been for the snails to be returned to the wild, after the mine was rehabilitated through a technique called Vegetation Direct Transfer (VDT).
It involves digging up the original habitat, storing it offsite, then rolling it back on to the ground like artificial turf.
At the time the wildlife permit was approved, there was uncertainty about whether VDT would work, given the highly specific habitat the species had evolved in.
The uncertainty was exacerbated by the speed of the process – Solid Energy had already sold some of the coal beneath the snails, and wanted to proceed quickly. When a permit to move the snails was granted by then Conservation Minister Chris Carter, teams of people crawled over the plateau, ripping into the soil to find as many snails as possible.
Before the search, there was estimated to be 250 to 500 left, and certainly no more than 1000. In total, they found more than 6000 live snails, along with about 8000 eggs. It was both good news and bad news. That there were more snails than expected was promising for its survival, but because they were all confined to a small area, they were at risk of a serious event, like a fire or a drought.
There was nowhere for the snails to go. The first group was taken to Nelson, but when it became clear there would be too many, they were hurriedly shifted to Hokitika in chilly bins.
‘‘The terrible haste with which this happened should never have eventuated,’’ says Debs Martin of Forest & Bird, who was involved in the fight to save the snails. ‘‘For those that were desperately doing what they could, and caring about it, it was a really difficult time.’’
What happens now is still unknown. There has been debate within DOC about the future of the programme, revealed in documents obtained under the Official Information Act. It included an apparent decision to mothball the facility this year, which was deferred when experts said it would be an enormous risk to release the snails into a habitat that may not be suitable.
One issue is whether the VDT area on the former mine site is good enough to sustain a population. The restored area has small chasms and invasive native weeds have prospered, making it markedly different from the original habitat.
The last bit remaining – the DOC triangle – has been mined on three sides, resulting in steep, eroding cliffs further chipping into the small habitat.
Some snails have been shifted elsewhere. Another site is beneath the ridgeline, in the DOC estate, but the conditions are different. Chopping about 30m from the mountaintop has meant less cloud cover, which could mean less moisture, which is vital for snails to survive.
A release would be particularly risky for some of the snails in particular, the expert advice noted. After the P. augusta were moved, it was discovered there are three morphologies, separated long ago and each set on their own evolutionary paths.
Nearly all of the more than 6000 snails collected were from the northern end, which had yet to be mined. But 24 snails were collected from the south, which had already been destroyed, and are different enough to qualify as a subspecies. A few more were in the middle, a sort of hybrid between south and north.
Five of the original 24 southern snails are still alive, each well into their 20s. They have successfully reproduced, and now there are around 150 southern P. augusta, most of them babies. Releasing them all at once would all but ensure a possible sub-species’ extinction.
In her description of the species, written after the peak was gone, Walker said the name Augustus – which means to inspire, to be dignified – was a fitting memorial to what had been lost.
In a parallel universe, Mt Augustus still exists, and the snails live happily in their odd little habitat. Walker looked carefully at the bag and noticed the subtle differences only she could have spotted. There was more habitat remaining, with more snails, and a population could have been saved. P.
augusta are not snails but stunning birds that soar, animals the public love and campaign for.
Instead, they are snails, entering their second decade in a fridge.