map of global routes of ship-borne invasive species

From the BBC. 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. The research is published in the Journal Ecology Letters.

Scientists mapped the global routes taken by cargo ships over a two-year period

Marine species are taken in with ballast water on freighters and wreak havoc in new locations, driving natives to extinction.

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. The model combines information such as shipping routes, ship sizes, temperatures and biogeography to come up with local forecasts of invasion probabilities.