In the movie "Independence Day," alien invaders arrive in big ships and inflict catastrophic damage before being subdued by an earthling's scientific ingenuity.
Off screen, alien invaders in big ships are inflicting real, if less apocalyptic damage on our environment and economy. And so far scientific ingenuity has not been able to defeat them.
These aliens are marine organisms - hundreds of species of fish, mollusks, crustaceans, jellyfish, sponges, worms, plankton, and microorganisms. They are in ballast water dumped in or near our harbors, estuaries, and inland waterways by cargo ships from around the world.
These alien invaders cause human health problems, cost the economy many millions of dollars a year, and inflict serious damage on our marine aquatic systems, driving out native species.
The already infamous zebra mussel, which arrived little more than a decade ago, causes major problems in the Great Lakes, clogging intake and drainage pipes and wreaking havoc with drinking water and hydropower systems. The toxic red tides that have made shellfish and other seafood dangerous to eat are known to contain many organisms from distant waters. Hundreds of millions of Asian clams now cover the bottom of San Francisco Bay, where they are consuming a disproportionate share of the food supply on which other marine organisms depend.
James T. Carlton, director of maritime studies for Williams College and Mystic Seaport in Connecticut, is a leading expert on invasive marine species. He has pointed out that ballast water collected by ships elsewhere and discharged in US waters carries many pathogens. But the greatest danger, he believes, is that humans - by introducing exotic species with little understanding of the consequences - are upsetting the natural balance of marine ecosystems that have evolved over millions of years.
Not only US waters are under attack. Marine systems around the world, particularly enclosed bodies of water like the Mediterranean and Black Seas, have long been infested by nonindigenous species. The problem is not new. For centuries worms and barnacles on the bottom of wooden sailing ships carried a substantial cargo of new life forms to every shore they touched. But in recent times the explosion of international trade, together with the practice of dumping huge volumes of ballast water by bigger and faster ships, has dramatically accelerated the process - giving a new meaning to the concept of one world.
A political as well as scientific consensus has been reached that the dumping must be sharply reduced. In October, Congress passed legislation for ships to discharge ballast and take on fresh water on the high seas. The procedure is voluntary. But the Coast Guard monitors it, and it could and should become mandatory if shipping operators do not comply on their own.
The International Maritime Organization, an arm of the United Nations, is seeking to devise protocols for managing water on the high seas. New technologies using heating and filtration systems are being developed to rid ballast of alien species before it is discharged. Efforts are also being made to provide shippers with more information about what is in their ballast water and the damage it creates.
While these are steps in the right direction, more concerted private and governmental action is needed. The shipping industry should step up to the challenge by investing in developing new ballast water technology aimed at eliminating organisms that pose a threat to marine ecosystems and public health. The government should develop a uniform set of standards and regulations to prevent the introduction of exotic marine species in domestic waters and should take measures to strengthen coordination between federal and state authorities to ensure adequate compliance.
Before the alien invasion gets worse, the maritime industry, with the support of federal and international agencies, must redouble their efforts to bring about an "independence day" for America's marine environment.
*Joshua Reichert directs the Environment Program of the Pew Charitable Trusts.