Arctic Science Journeys
Radio Script
1996

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Unwanted Ballast Hitchhikers
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"We're concerned that, as scientists seem to be concerned, that non-indigenous species could upset the ecosystem. There is that potential and it's happened in other places."

One of those places is the Great Lakes, where European zebra mussels made their way in the 1980s in the ballast tanks of cargo ships. The mussels found the Great Lakes to their liking and now cause millions of dollars in damage each year to ships, power plant cooling pipes, and city water supplies. Andy Cohen is a marine scientist at the University of California Berkeley who recently completed a study of non-native species in San Francisco Bay.

"We found 231 species of introduced organisms in the San Francisco bay system. We now have a new organism show up and become established every 15 weeks. We think the increase in the rate of invasion is largely due to ballast water."

Cohen says once established, the new species compete with native species, often driving them out of their habitats, and dramatically altering the ecosystem. One solution is to require that ships flush their ballast tanks while still far at sea, where--in theory at least--any non-native species would not likely survive. Likewise, any deepwater species brought onto the ship during the exchange would not fare well in the nearshore environment. It's a solution Congress included in recent legislation allowing the foreign export of Alaska crude oil. But while the requirement is expected to reduce the risks, it won't eliminate them. The RCAC's Leann Ferry.

"As tankers exchange their ballast water in the Gulf of Alaska, or on the high sea, we're not sure that the way the currents move, we're not sure whether those non-indigenous species will be carried right back into Prince William Sound. So we're worried about that as well."

Also of concern to Ferry is the possibility that marine organisms may not be flushed out in the ballast exchange. Instead, they may cling to the sides of the hull or remain in sediments at the bottom of the tanker. And then there is the problem of what to do with ballast water carried in tanks that also contain oil. This water cannot be dumped at sea, but must be treated at the Alaska pipeline terminal in Valdez.

"That ballast water treatment facility which treats the oil-water mix which would potentially have non-indigenous species in it, that treatment facility is not set up to treat organisms, it is only set up to remove oil. So we don't know whether that is also a pathway for non-indigenous species to get into Prince William Sound."

Finally, the ballast exchange rule applies only to vessels coming from foreign ports. Rick Steiner, a marine extension agent at the University of Alaska Fairbanks, points out that ships coming from U.S ports have never been required to exchange their ballast water.

"The potential for introduction of exotic species was never considered an issue. In other words we already could have and I suspect we already have introduced. I'm not sure we've introduced foreign species into the sound this way, but probably."

Further restrictions, such as requiring all tankers coming to Alaska to exchange their ballast at sea, are being debated as Congress considers the Invasive Species Act. The proposed legislation also calls for the study of technologies that could kill organisms in the ballast and a monitoring program to track the introduction of non-native species. For Arctic Science Journeys, this is Debra Damron.