Ballast water and the 'ecological roulette'

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MYSTIC, Conn. — Scientist James T. Carlton's influence has changed not only marine science, but the world.

Take ballast water research, for example.

Ballast water fills compartments in empty cargo ships to stabilize boats during their voyages. When the boat receives cargo, it discharges ballast water and the organisms it holds.

While it helps the maritime industry, this is an example of "ecological roulette," a term coined by Carlton, who is a faculty member at Williams College and former director of the Williams College-Mystic Seaport Maritime Studies Program in Mystic, Conn.

Ecological roulette describes how human activity transports species to new areas and creates the possibility for introduced species to become invasive.

In the late 1980s, the invasive zebra mussels colonized the Great Lakes. In Ohio, water stopped running in people's homes because zebra mussels clogged the water infrastructure, Carlton said.

Policymakers sought out experts in the subject — and found Carlton.

"In 1989, the only research lab in North America working on [ballast water] was mine in Oregon," Carlton said.

He had begun researching ballast water when he was a post-doctoral fellow at the Marine Biology Laboratory in Woods Hole. Carlton moved to the University of Oregon in 1986, where he expanded ballast water research.

As policy was being made, Carlton testified before Congress, one of seven times throughout his career.

In 1990, the federal Nonindigenous Aquatic Nuisance Prevention and Control Act was passed and in part targeted ballast water management. In 1991, the International Maritime Organization issued guidelines to ballast water management practices.

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Since then, domestic and international legislation on ballast water management has been updated.

"Ballast water legislation is due to Jim Carlton. Period," said John Chapman, an adjunct faculty member at the Oregon State University Department of Fisheries and Wildlife. Chapman and Carlton have collaborated for decades.

Decades later, Carlton's work remains cutting edge.

After an earthquake and tsunami hit Japan in 2011, items washed into the Pacific Ocean. A year later, Chapman called Carlton to tell him about a dock that landed in Oregon, covered in Asian species that rafted, or drifted, from Japan.

For centuries, items have rafted without bringing invasive species with them. However, this time, that wasn't the case.

Working with over 75 scientists, Carlton and Chapman identified close to 300 species that came ashore in North America over several years. They realized that the species that survived the journey across the Pacific were attached to man-made materials, like plastic.

Their research suggests that man-made materials will be an increasing method of transport for invasive species, due to the increase in plastic use worldwide and as climate change impacts storms, making storms more frequent and intense.

In March, Carlton and a collaborator from the Smithsonian Environmental Research Center and the Charles Darwin Foundation published research that identified the world's largest increase of invasive species in a marine tropical environment.

They worked in the Gal pagos Islands, where, before their research, there were only five named invasive species. The team identified 48 additional invasive species.

Earlier, Carlton's research on ballast water shaped domestic and international law. Those laws are why, in isolated boat launch areas, people see signs asking patrons to remove invasive species, like zebra mussels and milfoil, from their boats.

"That's very satisfying, of course," Carlton said of seeing his work move from academia to public action. "It took a long time to get there because we compete so much for the public's attention on so many issues," Carlton said.


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