Sea Grant ballast water specialist confronts a world of aquatic nuisance species

"Studies have determined that thousands of species of marine life are currently being transported in ballast water."

Bathed in early morning light, the Mita Maru, a 900-foot-long freighter leaves Hong Kong Harbor, bound for the Port of Seattle to pick up a load of grain. For this leg of its journey, the ship is empty—or so it seems. Within the ship's cargo hold and ballast tanks are millions of gallons of seawater, drawn from the Asian harbor to lend stability and trim to the vessel during its 18-day ocean crossing.

The ship's ballast water contains a mini-menagerie of aquatic organisms— minute jellyfish, larval mussels and barnacles, marine worms, tiny shrimp-like copepods and juvenile fish. These creatures share their confines with an assortment of single-celled plants and even smaller bacteria and viruses.

Many of these organisms can withstand the hardships of a journey across the Pacific Ocean. When the ship docks in Seattle, unloads its cargo and empties its ballast tanks, the plants, animals and microbes are unintentionally released into Puget Sound.

A History of Introductions
This is probably how the zebra mussel, a fingernail-sized mollusk from the Black, Caspian and Azov seas entered the Great Lakes in the late 1980s. Since their introduction, zebra mussels have spread rapidly to all of the Great Lakes and to waterways in many U.S. states, as well as Ontario and Quebec. Growing in dense clumps, the mussels can encrust and foul facilities at power plants, fish ladders and industrial facilities. To date, natural resource managers have been powerless to stop the mussels' spread.

Releases of ships' ballast water have also been blamed for the spread of the bacteria known to cause cholera. In the Chesapeake Bay, for example, researchers have identified a new strain of Vibrio cholerae, the organism that causes cholera, with origins in the Mediterranean or North seas. Health officials in Delaware, Maryland and Virginia must remain vigilant to prevent outbreaks of the disease caused by this particular strain.

Introductions of exotic plankton species can shift the balance of aquatic ecosystems. "Studies have determined that thousands of species of marine life are currently being transported in ballast water," says Russell Herwig, the Washington Sea Grant Program's new Marine Ballast Water Specialist. "It's unclear what the long-term effects of such large-scale introductions will be, or which of the species could establish themselves in a new environment."

Smith Calls
A Research Associate Professor with the University of Washington's School of Aquatic and Fishery Sciences, Herwig became fascinated with ballast water issues after a visit with Scott Smith, Aquatic Nuisance Species Coordinator for the Washington Department of Fish and Wildlife. Smith challenged Herwig and several other UW scientists to conduct research on effective treatment and safe disposal of ballast water.

"At the time, most of the attention was being devoted to the East Coast and Great Lakes," Smith recalls. "We needed someone to address the unanswered questions on our coast as well."

Answering Smith's call to action, Herwig launched an ambitious campaign to collect data from commercial ships in Washington's waters and to review the various treatment options under consideration at that time.

To obtain the cooperation of captains and crews, Herwig and UW co-investigators Jeff Cordell, Marcia House and Jake Perrins made contacts with the agents of shipping companies and other marine trade organizations at the ports of Tacoma, Seattle and Olympia. Each morning, the UW scientists would receive faxes from the Puget Sound Marine Exchange, telling them which ships would be docking in Puget Sound that day. Then, they would contact the shipping agents, arrange to board one or more of those ships, and take samples of the water in the ships' ballast tanks.

"We were really asking a lot from the ships' crews," Herwig explains. "We wanted to collect samples of water and zooplankton. This required access to a ballast tank through a service hatch, or manway—an access secured with a few dozen bolts, some rusted in place since last time the ship was serviced. Most of the ships' crews were extremely cooperative and very interested in watching our sampling efforts."

Once the crusty hatches were cracked open, Herwig's team would collect plankton samples, pulling a small plankton net, or "tow," through the tank. One tow would amass about 5,000 planktonic organisms in its stocking-shaped sieve, according to Cordell. Microbe-laden water samples were also collected in five-liter Niskin bottles, for subsequent analysis in the lab.

An Unfamiliar Zoo
While sorting the plankton, Cordell and research scientist Olga Kalata, a Russian expert on plankton from Asia, could distinguish foreign species from those native to North America's west coast. They could also recognize species associated with coastal and open-ocean habitats.

(Left) A University of Washington graduate student examines plankton under a microscope; (Right) A low-tech counting device is used to categorize and count plankton. (larger view)

The second distinction is especially valuable in gauging the effectiveness of what scientists call mid-oceanic exchange. To reduce the possibility of introducing exotic aquatic organisms, the Washington State Legislature recently approved a bill requiring trans-oceanic vessels to empty and refill their ballast tanks in the open ocean. This greatly reduces the chances of ships ferrying organisms from one nearshore area to another.

Alas, seawater swapping is probably not sufficient to eliminate the threats from ballast water releases. The designs of most ballast tanks make it difficult to drain every drop of water or replace all of the living organisms in a ballast tank, says Herwig. Sediments also may accumulate in the nooks and crannies of a ballast tank. Living organisms and resting stages of organisms may accumulate in the sediments.

Furthermore, the state's ballast water regulation has a loophole, according to Scott Smith. A ship's crew can be exempted from making mid-water exchanges if stormy seas or other conditions would present insurmountable safety hazards.

Currently, Herwig and the UW team are exploring the effectiveness of ozone and ultra-violet disinfection techniques and other technologies to treat ballast water onboard ships. "These technologies may be extremely costly to install, so only the larger, better funded shipping operations could consider them," says Herwig.

A less costly treatment involves using a biocide—chlorine, glutaraldehyde (a chemical fixative used in electron microscopy) or other chemicals to kill the mini-menagerie inside ballast tanks. While such treatments could minimize or eliminate the problems inside the tank, they might cause other problems when treated water is released into the environment.

Obtaining Industry Buy-In
"Wherever our research takes us, it's essential that we work closely with the shipping industry," Herwig notes. "There's no point in coming up with measures that are too impractical to be implemented. What shipping company would be eager to adopt a technology that took up three-fourths of a cargo hold? Understanding and solving the problems associated with ballast water also requires a multidisciplinary approach, with teams of scientists, engineers and representatives from the shipping and regulatory communities."

For this reason, Herwig is pleased to be working for Sea Grant, a program with a long history of successful collaboration with the marine industries. "It's our job to provide the scientific findings to support win-win solutions for the future," he says.

"As the second state in the nation to pass ballast water regulations, Washington has become a leader in aquatic nuisance species control," offers Herwig. "It's great to be part of a team that's addressing the issues of ballast water introductions before they become problems too vast to control.