Resumen de Hong Kong at high risk of alien invasions
Aliens don't strike everywhere in equal measure. The first comprehensive assessment of the risk posed by ballast water has identified 20 hotspots that are particularly vulnerable to being invaded by species stowed away inside the bowels of cargo ships. Now a team led by Bernd Blasius of the University of Oldenburg in Germany says that most of the threat is to a handful of ports. Of more than 1,400 ports studied, they estimate that just 20 carry 39% of the risk of invasions. The risk for most other ports was negligible. The authors mapped nearly 3 million ship journeys and assessed the danger their ballast water posed. An alien invader is most likely to be released if the journey is not too long--in which case the critter may die en route--and not too short--in which case it may already be present locally. The riskiest journeys turn out to be between 8,000 and 10,000 kilometers--roughly the distance from Shanghai to San Francisco.
