The discovery in Tampa Bay of an exotic mussel native to Asia provided a timely focus for scientists and shippers who gathered recently in Tampa for a 2-day workshop on aquatic invasive species and the shipping industry.

The workshop explored ways to prevent unwanted plants and animals from entering the bay in ballast water taken on by a ship in one port for balance and then discharged in another. Bay managers suspect that is how the Asian green mussel, Perna viridis, hitchhiked to Tampa Bay --where it was found last summer clogging intake pipes at Tampa Electric Company's Big Bend power plant. Since then, the mussel has been found by the thousands on three of the four bridges spanning the bay. Researchers studying the mussel report that many of the mussels in the bay are three inches long and encrusted with barnacles, indicating they have been here for some time. Additionally, research shows the mussels are capable of reproduction when only an inch long, and are spawning in the bay.

When we first started planning the invasive species workshop, we didn't think we had any aquatic invasive species in the bay, said Holly Greening, Senior Scientist for the Tampa Bay Estuary Program. AFinding out about the green mussel certainly lent a sense of urgency to the workshop.

The workshop was organized by the Tampa Bay Estuary Program in partnership with a host of public and private organizations. The goal was to bring the scientific and shipping communities together to share their knowledge and concerns. Topics included an assessment of the potential threats posed to Tampa Bay and similar coastal waters by invasive species; methods to prevent or eliminate exotic species invasions; and the implications of new policies governing ballast water exchange.

Shipping activities are the primary route of introduction for aquatic invasive species in coastal waters. A new policy being implemented by the U.S. Coast Guard calls for shippers to report the origin of their ballast water and what they expect to do with it. The policy also requests that shippers voluntarily discharge their ballast in the salty open ocean, where few hitchhiking plants or animals are likely to survive.

Emerging technologies discussed at the workshop that may eventually be helpful in Asanitizing ballast water include special filtering systems using UV light, biocides and shoreside treatment stations.

Once exotic species gain a toehold, they may out compete more beneficial native species, introduce diseases to native stocks, clog water intake pipes and blanket dock and bridge pilings. The zebra mussel, an interloper from Southeast Europe that is now found in 20 Midwest and Northeast states, has caused billions of dollars in damage to pipes and water control structures.

Speakers at the Tampa workshop included representatives of the Chamber of Shipping of America, the U.S. Environmental Protection Agency, the U.S. Geological Survey, and the American Association of Port Authorities, along with scientists from a variety of universities and research institutions.

A highlight of the workshop was a talk by Dr. Henry Lee, a research scientist with the EPA in San Francisco -- which currently holds the title of the nation's Amost highly invaded estuary. Dr. Lee reported that there are presently 212 identified non-indigenous species in the San Francisco Bay-Delta, and that exotic species are now being introduced at the rate of one every 14 weeks.

Florida's warm, moist climate, isolated peninsular geography and myriad manmade or altered habitats all combine to make the state an ideal candidate for a variety of exotic, potentially harmful species to flourish. In fact, Dr. Bob Doren of the U.S. Fish and Wildlife Service told participants that Florida is second only to Hawaii in total number of exotic plants and animals, with more than 1,000 known invasives. Recent research conducted by several scientists indicates that non-indigenous species account for about one-quarter of all the plants, 42 percent of the reptiles, 16 percent of the fish and 23 percent of the mammals in Florida.

While shipping activities are believed to be the primary avenue of introduction for aquatic invaders, other sources include aquaculture facilities and the pet and aquarium trades. Many of Florida's most prolific and pesky intruders were released - either inadvertently or intentionally - by residents unaware of the potentially devastating consequences of their actions.

Increased global trade heightens the potential for species to cross regions, and even continents. Chamber of Shipping representative Kathy Metcalf said her industry recognizes the extent and seriousness of the problem, and supports measures to restrict the transport of species in ballast water as long as the measures are fair and equitable.

Roundtable discussions at lunch allowed workshop participants to discuss specific issues, such as viable alternatives to ballast water; how to more accurately detect and assess the presence of exotic species; and whether a non-regulatory approach to ballast water management would be effective. A somewhat surprising response from all participants was that a regulatory mechanism was needed to drive both public and private participation in ballast water management and treatment strategies.

The input provided by workshop participants will help the Estuary Program refine its monitoring program to more rapidly detect potentially harmful aquatic invasives, and develop policies to minimize the risks posed by such species.

The workshop was co-sponsored by the Tampa Bay Estuary Program, Tampa Port Authority, Gulf of Mexico Program, Louisiana and Florida Sea Grant Programs, U.S. Environmental Protection Agency, U.S. Geological Survey, The Florida Aquarium, National Marine Fisheries Service, Florida Marine Research Institute, Gee and Jenson, and URS Greiner Woodward Clyde.

For a summary of the workshop, log on to TBEP's web site at www.tbep.org or call (727) 893-2765.