By Matt McGrath
Environment correspondent, BBC News
Scientists have developed the first global model that analyses the routes taken by marine invasive species.
The researchers examined the movements of cargo ships around the world to identify the hot spots where these aquatic aliens might thrive.
Marine species are taken in with ballast water on freighters and wreak havoc in new locations, driving natives to extinction.
The research is published in the Journal Ecology Letters.
There has been a well-documented boom in global shipping over the past 20 years and this has led to growing numbers of species moving via ballast tanks, or by clinging to hulls.
Some ports such as San Francisco and Chesapeake Bay have reported several exotic new species arriving every year. Economic estimates indicate that marine invaders can have huge impacts that last for decades.
Now, scientists from the UK and Germany have developed a model that might help curb these unwanted visitors. They obtained detailed logs from nearly three million voyages that took place in 2007 and 2008.
Scientists mapped the global routes taken by cargo ships over a two-year period
“Our model combines information such as shipping routes, ship sizes, temperatures and biogeography to come up with local forecasts of invasion probabilities,” said Prof Bernd Blasius from the University of Oldenburg.
While this is a mathematical model, the researchers were able to adjust it by carrying out field observations. They were able to estimate the probability that a species can survive a journey and establish a population in a subsequent port of call.
“It is called ecological roulette,” said Dr Michael Gastner from the University of Bristol.
“The probability of winning from the perspective of the invader is really tiny – but because the number of attempts are now growing with more and bigger ships, you play this roulette so often that you become a likely winner sooner or later,” he added.
Thanks to the BBC
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