[1/2]A cane toad sits in a plastic bag after Graeme Sawyer, founder of Northern Territory group Frog Watch, removed it from his trap on a billabong May 11, 2005, located 120 km (75 miles) south of Darwin. REUTERS/David Gray /File Photo Purchase License Rights
LONDON, Sept 4 (Reuters) – Fishing grounds clogged with water hyacinths. Songbird eggs eaten by rats. Power plant pipes blocked by zebra mussels. And power lines were destroyed by brown tree snakes.
These are just a few examples of the environmental havoc being wreaked by invasive species, whose spread around the world has caused economic damage to quadruple every decade since 1970, scientists said Monday.
The team of 86 researchers from 49 countries published a four-year assessment of the global impact of some 3,500 harmful invasive species and found that the economic costs are now at least US$423 billion per year, with extraterrestrial invaders accounting for 60% recorded plant and animal deaths play a key role.
“We also know that this is a problem that’s going to get much, much worse,” said ecologist Helen Roy, co-chair of the United Nations Intergovernmental Science and Policy Platform on Biodiversity and Ecosystem Services (IPBES) report.
Warmer temperatures associated with climate change are expected to further drive the spread of invasive species.
Invasive species are plants or animals that are often moved by human activities and become established in an environment that has harmful effects. These range from the displacement of native wild animals and the destruction of infrastructure to threats to human health and livelihoods.
The effects are often slow to set in, but then they can be catastrophic.
Last month’s deadly wildfires in Hawaii were caused by flammable, invasive grasses brought over from Africa for cattle grazing, scientists say.
Invasive mosquito species can also spread diseases such as dengue fever, malaria, Zika and West Nile fever.
“Invasive species not only affect nature but also humans, causing terrible loss of life,” said the report’s co-chair Anibal Pauchard of the Chilean Institute of Ecology and Biodiversity.
eradicate invaders
About three quarters of the negative impacts of invasive species occur on land, particularly in forests, forests and agricultural areas.
While invasive organisms can come in many forms, including microbes, invertebrates and plants, animals, particularly predators, often have the greatest impact on the environment, Roy said.
Many species have evolved on islands without predators and are therefore “very naive,” said Pauchard, with few defenses. “Birds in New Zealand had no experience of rats until humans came and brought rats. Their nests are at ground level.”
However, it is difficult to get rid of invasive species once they are established.
On some small islands, trapping and poisoning have successfully eradicated invasive rats and rabbits. But larger populations that reproduce rapidly can be difficult. And invasive plants often leave their seeds dormant in the soil for years.
According to scientists, preventive measures through biosecurity at the borders and import controls are the most effective.
Last December, in the Kunming-Montreal Global Biodiversity Framework, world governments committed to reducing the introduction and establishment of priority invasive species by at least 50 percent by 2030.
Reporting by Gloria Dickie in London; Edited by Angus MacSwan
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