These headlines may seem harmless, but to marine scientists they are cause for alarm. Pesky critters from foreign lands and sea are invading in growing numbers. Many of them hitch a ride in the ballast water of ocean-going ships. Some have been purposefully introduced, but quickly spread out of control. A recent Connecticut Sea Grant study found that 15,000 new species are moved around the world by ballast water every week, though the vast majority of them never become established.
Biological invasions can dramatically alter community composition and ecosystem function.
Whitlatch has been studying invasive marine species for about 15 years. He points to the zebra mussel as an example of how just one organism can cause widespread damage. Two years ago, the damaging mollusk showed up in a Connecticut lake. The mussels rapidly form large reefs. They prevent fish from laying eggs, wipe out bottom-dwelling species, and clog water intake pipes at power plants.