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New Ballast Water Protocols Designed to Stop Invasive Species

EPA Partners with Coast Guard to Develop Ship Treatment System Protocols


Cargo ship traveling in open water

Marine organisms have been hitchhiking on ocean-going ships for probably as long as there has been long distance shipping. One significant source: the ballast water that vessels pump in and out of their hulls to keep stable as they unload cargo or maneuver at sea.

Unintentional releases of non-native invasive species have created ecological havoc in waterways throughout the world. For example, the  zebra mussel (Dreissena polymorpha), native to eastern Europe, was first discovered in the Great Lakes nearly 25 years ago, and the comb jellyfish (Mnemiopsis leidyi), native to North American waters, has invaded the Mediterranean Sea.

"The problem is that when ships are pulling in ballast water, all of the organisms, including microscopic zooplankton and phytoplankton, in that area also get pulled into the ballast tank," says EPA Environmental Protection Specialist Ray Frederick.

"Most of these organisms don't survive the voyage, but some do. When these more robust organisms are discharged into new environments, they often out-compete native species for food and shelter, and their populations explode resulting in widespread ecological imbalance. The zebra mussel has become the poster child for this problem."

To comply with new regulations from the U.S. Coast Guard (USCG) and proposed rules from the International Maritime Organization, many ships will elect to treat ballast water with manufactured devices that use a variety of disinfection technologies such as ozonation, UV filtration, electrochlorination, or various chemicals to kill micro-organisms.

Until recently, however, regulators couldn't be sure if the treatment systems designed for shipboard installations worked well enough to comply with USCG's regulations. To address this issue, the EPA and U.S. Coast Guard joined forces to develop new performance verification protocols that ensure the devices are effective at destroying organisms that could pose environmental and economic risks to the ports they visit.

"Together with the Coast Guard, the EPA has developed a standardized process to evaluate ballast water treatment systems that is technically sound and with appropriate levels of quality assurance. The resulting test reports are intended to provide highly credible and comparable data that is both transparent and available to anyone," Frederick said.

The Coast Guard has been working with EPA and a participating stakeholder group for the past 10 years on protocols for the treatment systems under the Environmental Technology Verification program, according to Dr. Richard Everett of the USCG's Environmental Standards Division.

Using a commercial ballast water treatment system, engineers and scientists at the Naval Research Laboratory (NRL) in Key West, Florida, validated the test protocol developed by EPA and the USCG. Researchers at NRL are also working on methods to test ballast water discharges for invasive organisms. Some of these methods are similar to pool test kits and will help Coast Guard inspectors and ship operators know if the treatment systems are functioning properly and if the ballast water is clean enough for discharge.

Everett says the economic and environmental impacts from species moved by ballast water should decline as a result of the new protocols, but the impacts may not be immediately evident. Everett says, "It has been well documented that many invasions are not recognized as having occurred for some time, often many years."

DNA Barcoding

So you have a sample of water from a ship’s ballast water, a pond, or a stream ecosystem. How do you find out what’s been in it?

Blue DNA  illustration on white background

The traditional method is the most obvious: comb through samples as thoroughly as possible in the lab, and identify each specimen you find. Needless to say, this is time consuming, labor-intensive, and slow — with surveys sometimes taking from six months to a year to complete.

Now, there’s a way to sidestep quantifying species in water samples by simple visual inspection. EPA scientists are using a technique called “DNA barcoding” to rapidly and accurately identify species in water samples.

Animals such as snails, worms, and insects leave genetic footprints behind in water they inhabit, and DNA barcoding can identify these signs.

“DNA barcoding comes at a comparable cost to older collection methods,” said EPA scientist Erik Pilgrim, who is using the method to study the health of ecosystems. “But barcoding is faster, and you get richer information with more taxonomic resolution.”

Instead of simply finding and counting species (which sometimes are not visually distinct), DNA barcoding relies on identifying short, species-specific sequences of a standard gene. This allows scientists to use the method to differentiate between many more species in water samples than they can with traditional lab methods. Once sequences are analyzed, they can be compared to existing DNA barcode databases, giving scientists a far more comprehensive picture of organisms in the water.

“This is good for bioassessment,” Pilgrim explained. “You can use the identifications you make to say something about the overall health of an ecosystem.”

DNA barcoding may also provide a way to identify invasive species, such as the kinds sometimes introduced by ocean-going ships’ ballast water.

“Barcoding may be a way for us to get early warnings of invasive species,” said Pilgrim.

More information on EPA’s DNA Barcoding Research

Learn More

EPA Safe and Sustainable Water Research

Safe Harbors (EPA story on invasive species research)

Predicting Invasive Species in the Great Lakes

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