One of the world’s most invasive species has been found in the UAE for the first time.
The Giant African Land Snail, which grows up to 20cm long, was discovered in Al Wathba on the outskirts of Abu Dhabi city.
The creature may have arrived on imported plant material, and although there is no record yet of it elsewhere in the country, experts said eliminating invasive species can be difficult.
In a new study, scientists analysed nine snails collected last year.
They analysed the snails' genes and found the nine belonged to four distinct groups, suggesting multiple invasion events. The researchers said the species’ arrival was almost certainly recent.
Published in the Biological Journal of the Linnean Society, the study describes how the snail, native to East Africa but introduced to new countries since the 1800s, is "one of the world's most invasive species" and may have caused significant harmful economic, ecological or health effects in at least 52 countries.
The study also looked at alien populations of the snail in China, India and West Africa.
Particular alien species sometimes multiply out of control because they have no natural predators in their new habitats, and the creatures or plants they eat have not evolved natural defences to them.
By killing or outcompeting them, invasive species harm their indigenous counterparts and have been described as the biggest threat to native animals and plants after climate change and habitat loss.
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The Giant African Land Snail eats crops and other vegetation and can spread bacteria that cause septicaemia in people and a roundworm associated with a severe form of meningitis.
Despite that, the snail is a popular pet – not least because it can grow to the size of a rabbit.
“Species such as the Giant African Land Snail have really high reproductive potential; they lay a lot of eggs and produce a lot of offspring, so their populations will increase in size quite rapidly,” said Prof Helen Roy, an invasive alien species specialist at the UK Centre for Ecology & Hydrology.
Although it reaches sexually mature first as a male, it goes on to become hermaphrodite, producing male and female sex cells simultaneously, allowing self-fertilisation.
As a result, Prof Roy said it could be “very difficult” to eliminate invertebrates like the snail once they became established in a new area.
The Environment Agency – Abu Dhabi was involved in the research and contributed to the recently published paper.
The organisation said there had been only “one record from one very localized area” of the snail in the UAE, adding that the creatures were being monitored as part of EAD’s “alien species” programme.
“Since it was only localized, the area was checked and any visible snails collected,” a spokesperson said. “It could become a problem if the species became widespread.”
Species such as the Giant African Land Snail are “passive dispersers”, said one of the paper’s authors, Fred Naggs of the Natural History Museum in London.
“They are primarily carried on goods, mostly on imported plants or soil associated with imported plant material,” he said.
“It might only take a tiny egg to source a population. The only ways to guard against this are for thorough checks to be carried out on imported goods and for any outbreaks to be promptly identified and eradicated.”
In some countries, tens of millions of dollars have been spent trying to eliminate alien species because of the harm they cause, so preventing new species from arriving is “a much better option”, according to Prof Tim Blackburn, a professor of invasion biology at University College London not connected to the new research.
Dan Eatherley, a UK-based environmental consultant and author of Invasive Aliens, a book about invasive species, suggested they were not always as harmful to local flora and fauna as suggested.
“There are surprisingly few cases of an invasive species alone causing extinction,” he said.
“Other man-made factors are often as much to blame.”