Look at what the cargo ship dragged in

In June, a Chesapeake Bay crabber made an unusual – and possibly ominous – catch. John Delp hauled up a trap holding a crab with what appeared to be fur on its pincers.

The Maryland Department of Natural Resources (DNR) caught wind of Mr. Delp's find and, after an examination, concluded it was a Chinese mitten crab, an exotic species native to East Asia and well established in San Francisco Bay, but never before seen on the East Coast. Immediately, the DNR issued an alert. One male crab wasn't proof of a breeding population, but it was cause for vigilance.

In August a second animal, caught years earlier and preserved in a waterman's freezer, came to light. Exactly how two Chinese mitten crabs – both male and both a continent away from the nearest known population – found their way to Chesapeake Bay is a mystery, but scientists suspect an old villain: ballast water.

Before setting sail, cargo ships take in vast amounts of water for stabilization, and then discharge the water at their destination. Only nominally filtered on uptake, this water, known as ballast, inevitably contains a host of organisms, ranging from algae to the larvae of various mollusk species to (at least in one case) an entire school of fish.

"Considering that there are over 30,000 ships at sea this morning," writes James Carlton, director of the Williams College-Mystic Seaport Maritime Studies Program, in an e-mail, "the total number of organisms and species in this global 'bioflow' on the morning your readers read your piece could be staggering – billions of individuals, and thousands of species."

Indeed, scientists have long considered ballast water the primary way invasive aquatic organisms are introduced. From the zebra mussel's arrival in the Great Lakes, to an American jellyfish severely disrupting Black Sea fisheries, the potential costs of accidental introduction of a species to new homes can be tremendous. Aquatic invasives cost the US $9 billion yearly, according to estimates by David Pimentel, professor emeritus of ecology and evolutionary biology at Cornell University in Ithaca, N.Y. Zebra and quagga mussels (a cousin to the zebra) alone cost the $1 billion annually.

As the cost of invasive species has become increasingly apparent, the adoption of – and technology for – ballast water management has become more pressing. California passed tough ballast-water standards in September, and last week the International Maritime Organization (IMO), the UN body charged with formulating international standards, met in London to discuss the issue. Meanwhile, companies worldwide are rushing to provide solutions for what may become a billion-dollar industry: the shipboard sterilization of large amounts of water.

Currently, the Coast Guard requires all ships entering US waters to exchange their ballast at least 200 nautical miles from shore where the ocean is at least a mile deep, or face a fine of up to $27,500 per day. Adapted to the lower salinity of coastal waters, organisms found in ballast water theoretically won't survive the higher salinity of the open ocean.

Enforcement of these measures since they became mandatory in 2004 – previously, they were voluntary – has reduced the number of organisms carried in ballast by 90 percent, says Gregory Ruiz, a marine ecologist at the Smithsonian Environmental Research Center in Edgewater, Md., who works with the Coast Guard on ballast water management. "Ships have radically changed the way they behave."

But others emphasize that ballast water exchange was meant to be an interim fix on the way to a more effective solution. Studies conducted in the Great Lakes, where mandatory ballast exchange has been in effect since 1996, indicate no slowdown in the introduction of exotic species, says Edward Mills, director of the Cornell Biological Field Station in Bridgeport, N.Y.

The problem, he says, are NOBOBs, an acronym for ships with No Ballast on Board, which are exempt from current regulations. Although their tanks don't contain water, they carry a layer of sediment that may harbor an array of organisms. When ships do take up ballast, after they have delivered their cargo, they inevitably "dribble the sediment throughout the lakes."

For this reason, environmental groups have long pressed for national guidelines specifying what discharged ballast water can and cannot contain. "We're not trying to dictate what kind of technologies they use," says Jennifer Nalbone, campaign director of Great Lakes United, a coalition of organizations dedicated to preserving and restoring the Great Lakes. "The standard is most important."

In a rare convergence of interests, the shipping industry – worried by the prospect of having to comply with standards that vary from country to country and even state to state – has also pushed for universal standards. "Ours is an international industry," says John Berge, vice president of the Pacific Merchant Shipping Association. "To suddenly be in a situation where you have to meet different standards throughout the world, it can create an untenable situation."

That situation may soon change. National ballast water discharge standards are "the No. 1 regulatory project for the Coast Guard," says Lt. Keith Donohue of the Guard's Environmental Standards Division, although he declined to specify a date beyond "very soon."

In 2004, the IMO announced its intention to provide international guidelines. And although the conventions have yet to be ratified by the 30 member nations, the mere suggestion of global regulation gave birth to a $10 billion to $15 billion industry overnight. "It just catapulted progress," says Allegra Cangelosi, a senior policy analyst at the Northeast-Midwest Institute, a nonprofit dedicated to the environmental quality of those regions.

Frustrated by what they see as lethargy at the federal level, and viewing proposed IMO standards as lax, some states have moved ahead alone. (The National Aquatic Invasive Species Act, itself an update of the 1996 National Invasive Species Act, has languished in Congress since 2003.)

Michigan enacted legislation in 2005 to require all incoming vessels to prove that either they will not discharge ballast water or that, if they do, they possess the technology to prevent the escape of aquatic organisms. The law takes effect in 2007. And in September, California Gov. Arnold Schwarzenegger signed a bill widely viewed as the country's most stringent. By 2020, ballast water discharged in California must contain no living organisms.

How that goal will be achieved is still unclear, but possible technologies run the gamut from filtration and biocides – substances that kill living organisms – to techniques with no long-term residue like ultraviolet radiation and heat treatment.

Once universal standards are in place, ballast water treatment solutions won't be difficult to develop, says Andrew Cohen, a marine biologist at the San Francisco Estuary Institute. "The basic problem is, how do you kill or remove organisms in a tank of water? And that just doesn't seem that daunting a challenge in the 21st century."

Improved shipping technology, more ships, faster voyages, and antipollution efforts over the past 100 years have contributed to the accelerating rate of exotic aquatic species appearing worldwide.

The use of seawater as ballast became widespread with the advent of steel-hulled steamships a century ago. Wooden sailing ships had used rocks, cargo, and other dry ballast to stay on an even keel.

Significantly faster, the new ships shortened the time stowaway organisms had to survive in order to arrive in – and colonize – new environs. In the 1850s, a trip from New York to San Francisco took up to three months. By the 1950s, it was weeks.

More trade has meant more ships. According to the International Maritime Organization, the number of ton-miles logged – a gross ton shipped one mile – quadrupled between 1965 and 2004. In 2004, a world trading fleet of 46,200 ships moved 6.76 billion gross tons 4 million miles.

In the same period, new canals linked previously isolated bodies of water. In 1952, the Volga-Don Canal joined the Sea of Azov and the Caspian Sea. In 1959, the St. Lawrence Seaway opened the Great Lakes to the Atlantic. The 1992 completion of Europe's Rhine-Main-Danube Canal linked the Rhine and Danube Rivers, permitting direct travel between the North and Black Seas.

Ironically, efforts to clean polluted waterways beginning in the 1980s may have helped disperse exotic species in Europe and North America. Toxic pollution levels may have served as a barrier before.

The infamous zebra mussel, which has spread throughout freshwater systems east of the Rockies over the past 18 years, is a case in point. Native to the Caspian Sea and long established in northern Europe, it colonized the Great Lakes only in the late 1980s, 30 years after the St. Lawrence Seaway opened, but just as pollution was abating.