Invasive Species "Stowaways" May Lose Rides on Ships

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Environmentally Benign

Although it's too early to determine whether using nitrogen to clear oxygen from the water will have any adverse environmental effects, the researchers say major negative effects are unlikely. Nitrogen makes up 78 percent of the atmosphere and deoxygenated water poses no threat.

The results of the research are published in the January issue of the journal Biological Conservation.

To test the effects of low oxygen levels on organisms in ballast water, Tamburri and co-author Kerstin Wasson simulated the conditions in ballast tanks. They investigated the effects of deoxygenation on the larvae of three diverse and devastating invasive species: the Australian reef-building tube worm (Ficopomatus enigmaticus), the European green shore crab (Carcinus maenas), and the zebra mussel (Dreissena polymorpha).

After two days of exposure to low oxygen levels in the water, 79 percent of the tubeworms, 82 percent of the zebra mussels, and 97 percent of the green shore crabs were dead.

"It's not perfect," Tamburri said of the approach. "It doesn't kill everything. But until international law mandates that ballast water contain no living organisms, why not require this technology that saves industry money and is also good for the environment."

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