Science, Tech & Environment

New Zealand on high alert in an effort to protect island nation from bio-invaders

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Kiwi orchard owner Paul Jones has grafted new varieties onto the stumps of vines killed by the bacteria PSA. (Photo by Sam Harnett.)

The arrival of humans in New Zealand 800 years ago began a trickle of disruptive new species to the isolated islands.

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Now that trickle has become a flood, and the country is ratcheting up its efforts to keep out keep out what they can, and limit the damage from what they can’t. At a ferry dock in the small town of Picton, a young man hands pamphlets to people waiting for the boat that runs between New Zealand’s two main islands.

He’s a bio-security officer, warning people about an invasive aquatic organism called didymo. It’s a brown algae known locally as “rock snot,” and it has infested waterways throughout the country’s south island since it was first seen here in 2004.

In an effort to stop its spread to the north island, government officers now routinely hose down any clothing, equipment or vehicles that might’ve come in contact with didymo before people can get on the boat.

If bio-security is a foreign concept to most visitors here, for New Zealanders it’s a fact of life. Invasive species have plagued the remote island chain ever since humans first arrived. Now globalization is intensifying the threat, and New Zealand is ratcheting up its response. The isolated island country spends more than $150 million annually on border screening, eradication and containment. This year, the government created a whole new department to better coordinate the effort.

“We are an island nation and we don’t have a lot of the pests and disease that are present in other countries,” said Wayne McNee, director-general of the new Primary Resources Ministry. “So on the plus side, because we don’t have those pests and diseases, we have a lot of biodiversity in New Zealand.”

On the down-side, though, when these things do arrive, they can wreak havoc. And McNee says increasing trade and tourism is making it harder than ever to keep them out. In the last decade alone, there have been incursions of rust fungi, didymo and a bacterium known as PSA that’s devastating kiwifruit, one of the country’s most important crops.

On his kiwifruit orchard outside of Te Puke, Paul Jones points out an infected vine that’s oozing a red goo.

“It looks like radiator rust,” Jones said. “The vine’s own vascular system is carrying it around and it does not have a future.”

Since officials first detected PSA here two years ago, it has spread to infect 60 percent of the country’s extremely valuable gold kiwifruit vines. Jones’s orchard does still have some healthy fruit, but before he’ll show it to you, Jones requires visitors to put on bright blue hairnets and get sprayed down with antibacterial solution.

“We’ve developed a set of hygiene standards, none of which we used to think about before PSA,” Jones said. “It’s costing us a lot of money just in terms of control mechanisms.”

The industry says it will be impossible to contain the disease. Instead, it’s trying to develop new strains of the fruit that are immune to the infection. But Jones says the outbreak has already ruined many growers.

The government acknowledges that no amount of security could keep out every biological stranger. Microbes can slip in with tourists, cargo ships, or even on gusts of wind from Australia, more than a thousand miles away. Many interlopers have even been brought in on purpose. Introduced livestock, crops and pets have become a big part of the landscape.

Some newcomers are a boon for the economy, like sheep, wine grapes and trout. Others have become a national nuisance.

Herb Christophers, with the department of conservation, says the list of imported mammals is a long one.

“Cats, rats — that’s Norway rats and ship rats — stoats, ferrets, weasels, which were introduced to control rabbits, which were introduced. Seven species of deer, pigs, goats...” he said. And he could go on.

Christophers says the naturalization of these pests served as a cautionary tale for a country with some of the most unusual wildlife on earth. Before humans arrived in the 13th century, the only native land mammals here were bats. Modern mammals hadn’t yet evolved when New Zealand broke away from the other continents about 85 million years ago. So thousands of unique animals evolved here instead, especially birds.

“We have a bird, which is nearly extinct, called a kokako, which fills the same role as a squirrel,” Christophers said. “We have other birds, which — why bother flying, when your food is on the ground — so their wings became vestigial, such as the kiwi. So it’s our national icon.”

But unique wildlife like the kokako and kiwi proved easy prey for many imported species. Imported creatures like rats, stoats and opossum have pushed dozens of native species into extinction and are now too pervasive to eradicate. The only hope is to contain them, which is a big part of the country’s bio-security efforts.

Ranger Duncan Kay is part of that effort. One recent day he tested out a spring-loaded stoat trap near the South Island’s Tai Poutini National Park.

“It’s got quite a bit of force,” Kay said as he set the trap. “So if the stoat puts his paw on that, he’s pretty much a gonner.”

Kay stepped back and tapped the trigger with a stick, to which the trap responded with a deadly thwack.

Traps like these are found all over New Zealand. So is a controversial pesticide that’s banned in many other countries because it is so deadly to mammals — the exact reason why New Zealand has become the world’s number one user.

It’s an extreme measure, perhaps, but the government believes it’s an important part of a broad national effort to fight back against invasive species.

Christophers says it’s not just about protecting New Zealand’s agriculture, or even its huge tourist industry. It’s about protecting the country’s national identity, for which there are no replacement strains.

“To retain what is individual about New Zealand, we want to retain that biodiversity,” Christophers said. “We don’t need anymore introductions, thank you very much.”

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