Some aliens arrived as stowaways. Others were brought in deliberately, for fun or profit. And others were so tiny that nobody noticed them until way too late.
They became a nightmare. They killed and devoured natives, stole their homes, sickened them with pathogens.
Science fiction? No: The alien invasion is happening right now.
It could be occurring in your garden. In the forest where you like to feel in harmony with nature. It is almost certainly unfolding on the farms that produce your food.
It is the tale of species that people bring to new habitats where they spread uncontrollably, ousting endemic wildlife and becoming major pests.
“Invasive species have a huge impact worldwide. In some countries, the cost is astronomical,” said Dave Richardson, director of the Centre of Excellence for Invasion Biology at South Africa’s University of Stellenbosch.
The International Union for Conservation of Nature (IUCN), staging a conference in South Korea next month, said foreign encroachment is the third-biggest source of species threat.
Take the US gray squirrel — “a rat with good PR,” enemies say — which is displacing Britain’s scrawnier red squirrel. Or the Burmese python, gorging on small mammals in Florida’s Everglades.
Invasive species inflict more than US$1.4 trillion in damage each year, or 5 percent of global GDP, according to an estimate made 11 years ago.
“Those numbers are controversial because it’s difficult to put finite figures on these sorts of things,” said Tim Blackburn, director of the Institute of Zoology at the Zoological Society of London. “But the impacts are pervasive and affect so many aspects of life. The cost has the potential to escalate as we take more species to more areas where they don’t naturally occur.”
Many costs are indirect. For instance, US farmers use truckloads of pesticides to control foreign weeds, while in central Europe, their counterparts are surrendering tracts of land to the giant hogweed, a toxic Asian shrub.
There is the bill from the European rabbit, introduced for food by British settlers to Australia and New Zealand only to become cursed for ravaging grasslands and crops.
In the southern US, Asian carp were imported in the 1970s to help clean up algae in commercial catfish ponds. Flooding washed the carp into the Mississippi River system, where they now threaten commercial and game fishing in the Great Lakes.
Invasive species have followed people throughout his odyssey.
Polynesians wiped out innumerable bird species as they island-hopped across the Pacific over eight centuries, bringing in rats that had stowed away on their ocean-going canoes.
The trend accelerated in the early to mid-19th century.
European species were shipped out to the colonies in Africa and Australasia to provide food or company, and exotics were brought back to Europe.
“There was a great flowering of ‘acclimatization societies,’ which were specifically set up to introduce new species to areas around the world,” Blackburn said. “In fact, the Zoological Society of London, the organization I work for, envisioned a golden age where we would have herds of elands roaming over the south of England.”
Faster travel — steamship, then jet plane — accelerated the problem as global trade really took off.
Headaches include the zebra mussel, which has infested US waterways after hitching a ride from Europe in ships’ ballast water. Another is the verroa mite, reported in countries in three continents, which is wiping out honey bees that pollinate many crops.
Even tinier is the chytrid fungus being spread to wild amphibians through the sale of pet frogs and frogs for food. As frog numbers plummet, insect populations surge — another hidden cost.
In many countries, national border controls are often lax and laws are riddled with loopholes because of interest groups that trade in non-native species, Richardson said.
He said he knew of nowhere that firmly applies “polluter pays” principles, whereby someone who introduces a pest pays the bill to get rid of it.
As for international cooperation, there has been progress — for instance, in marine conventions that oblige ships to exchange ballast water in mid-ocean.
However, “in many instances, treaties and conventions do not have teeth,” Richardson said.
Eradicating these threats is costly and often impossible, for it requires lots of manpower, sometimes over many years. Introducing a predator animal or insect to attack the invader sometimes makes things worse. Jean-Philippe Siblet, director of Natural Heritage at France’s Museum of Natural History, said eradication had to be “smart.”
Conservationists must distinguish between useful, introduced species and those that become a burden.
“It’s the globalization of nature, and we’re going to have a hard time stopping it,” he said.
Nearly half of China’s major cities are suffering “moderate to severe” levels of subsidence, putting millions of people at risk of flooding, especially as sea levels rise, according to a study of nationwide satellite data released yesterday. The authors of the paper, published by the journal Science, found that 45 percent of China’s urban land was sinking faster than 3mm per year, with 16 percent at more than 10mm per year, driven not only by declining water tables, but also the sheer weight of the built environment. With China’s urban population already in excess of 900 million people, “even a small portion
UNSETTLING IMAGES: The scene took place in front of TV crews covering the Trump trial, with a CNN anchor calling it an ‘emotional and unbelievably disturbing moment’ A man who doused himself in an accelerant and set himself on fire outside the courthouse where former US president Donald Trump is on trial has died, police said yesterday. The New York City Police Department (NYPD) said the man was declared dead by staff at an area hospital. The man was in Collect Pond Park at about 1:30pm on Friday when he took out pamphlets espousing conspiracy theories, tossed them around, then doused himself in an accelerant and set himself on fire, officials and witnesses said. A large number of police officers were nearby when it happened. Some officers and bystanders rushed
Beijing is continuing to commit genocide and crimes against humanity against Uyghurs and other Muslim minorities in its western Xinjiang province, U.S. Secretary of State Antony Blinken said in a report published on Monday, ahead of his planned visit to China this week. The State Department’s annual human rights report, which documents abuses recorded all over the world during the previous calendar year, repeated language from previous years on the treatment of Muslims in Xinjiang, but the publication raises the issue ahead of delicate talks, including on the war in Ukraine and global trade, between the top U.S. diplomat and Chinese
HYPOCRISY? The Chinese Ministry of Foreign Affairs yesterday asked whether Biden was talking about China or the US when he used the word ‘xenophobic’ US President Joe Biden on Wednesday called for a hike in steel tariffs on China, accusing Beijing of cheating as he spoke at a campaign event in Pennsylvania. Biden accused China of xenophobia, too, in a speech to union members in Pittsburgh. “They’re not competing, they’re cheating. They’re cheating and we’ve seen the damage here in America,” Biden said. Chinese steel companies “don’t need to worry about making a profit because the Chinese government is subsidizing them so heavily,” he said. Biden said he had called for the US Trade Representative to triple the tariff rates for Chinese steel and aluminum if Beijing was