These are the “alien” species wreaking havoc across the globe

The charming fellow in the picture above is the Chinese mitten crab.

There are two issues with its name: first of all, the word “mitten” suggests something wooly and inoffensive, like a cartoon cat, and this crab is most definitely not. Free of its normal predators and disease, the crab has proceeded to viciously prey on other creatures wherever it goes. Which leads me to the second misnomer: although it began life in China and Korea, it now has roots in Europe and the United States, most recently seen setting up a thriving but brutal community in the Thames.

This is just one example of alien species reeking havoc in new ecosystems.

Whether it’s rabbits running amok in Australia or the Crown-of-thorns starfish making coral more susceptible to bleaching, the spread of animal and plant life around the globe via human activity is often a pretty bad thing, disrupting local food chains and carefully balanced ecosystems. Now we have an idea of how bad: Scientists have begun to compile the Global Register of Introduced and Invasive Species (GRIIS) as a general health check to our world’s various habitats, and the results are a touch worrying.

Data from the first 20 countries shows that a fifth of the 6,414 alien plant and animal species catalogued are causing damage locally. And although that damage is most obviously environmental, it extends well beyond that into human society, causing public health problems and costing the taxpayer. In Britain, a conservative estimate from 2010 suggested the cost to the treasury was some £1.7 billion per year.alien_species_catalogued_in_a_global_register_-_1

The GRIIS doesn’t single out any alien species, instead being about “all of them and about the many thousands of species that have become naturalised outside of their historical ranges across the world as a result of human activity,” Melodie McGeoch of the IUCN Invasive Species Specialist Group told the BBC. “Until now there has been highly uneven distribution of knowledge on invasive species globally.”

The hope is that by cataloguing the animals and plant that cause issues, biological invasions can be managed – given the main drivers of the global spread is human activity: cross-border trade and transport. The Chinese mitten crab, for example, likely left the far east in ballast water in ships making the same journey.

Of the 6,414 species currently tagged, over 80% have been shown to have an impact in at least one or two countries. The number of species catalogued, however, ranges widely from country to country – with South Africa having 2,107 to Mongolia’s 77.

The study was published in Nature.

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