New Rules Aim to Stop Invasive Species in Ballast Water

Nearly a century after the first documented introduction of an alien species via ballast water, national and international agencies are finally firming up new regulations to reduce the potential for other invasive species to be transferred.

Three distinct organizations — the U.S. Coast Guard, the U.S. Environmental Protection Agency and the International Maritime Organization — all have proposals on the table that would require ballast water to meet certain standards before discharge.

The challenge has been the fact that ballast water is critical to the safety of a ship. Exchanging it at sea can be dangerous — as shown by the near-sinking of the car carrier Cougar Ace in 2006. Treating ballast water to kill stowaways is technically challenging and new technologies are just beginning to become available.

Left, green mussels, the largest mussels in the world, are believed to have been introduced to Tampa Bay in ballast water. Below, ships discharge ballast water as they take on cargo at the rate of a gallon per minute day in and day out in Tampa Bay. Photo courtesy of the Univeristy of Florida.

“Ballast is not really optional, it’s essential to maintaining stability,” notes Bill Richardson, research associate at the Florida Fish and Wildlife Research Institute who conducted a series of tests on ballast water between 2003 and 2006. Ballast has been used for hundreds of years, he adds. “The rocks at Ballast Point were discharged from ships in the early 1800s when Ballast Point was a prominent port for shipping cattle. The accumulated ballast is said to include rock from almost every seacoast in the world.”

With the advent of large metal ships, water became the preferred form of ballast and it’s used in nearly every cargo ship. Ballast water is discharged into Tampa Bay at an average rate of a gallon per minute, day in and day out, Richardson notes. Scientists estimate that 65 non-native plant and animal species have been established in the Tampa Bay estuary, with ballast water considered a possible route of introduction.

Asian green mussels, the fastest-growing mussel in the world, probably entered Tampa Bay in ballast water in a ship from Trinidad. When they were first discovered blocking an intake valve at a TECO power plant in 1999, experts feared the worst. As it turned out, the mussels are surviving in Tampa Bay but not creating the environmental disaster caused by the zebra and quagga mussels in the Great Lakes where they have consumed so much of the algae that the base of the food web has shifted. The Great Lakes also are contending with the rapidly reproducing round goby and the parasitic sea lamprey. In the Chesapeake Bay, the Chinese mitten crab and the rapa whelk are wrecking environmental havoc.

“We’ve been very lucky in Tampa Bay,” notes Phillip Steadman, environmental director for the Port of Tampa.
Eliminating Organisms is Technically Challenging

While it’s clear that invasive organisms travel in ballast water, the most effective way to prevent them is much less clear. The U.S. Coast Guard established voluntary ballast water management guidelines in 1998, requiring that ballast water be exchanged 200 miles offshore, retained onboard the vessel or treated to kill living organisms.

The voluntary requirements were deemed ineffective so they became mandatory in 2004. Even so, the FWRI report (see sidebar) shows that treatment methods did not eliminate either living algae or dormant-stage cysts of microalgae in a significant proportion of the samples taken between 2003 and 2006.

The U.S. Environmental Protection Agency was sued by environmental groups in 2000 for failing to regulate ballast water as a point source for contamination, contending that the agency has jurisdiction under the Clean Water Act.

New rules were issued in 2008 requiring ships to exchange ballast at sea or rinse tanks with salt water before entering U.S. waters. Both the Coast Guard and the EPA are finalizing new regulations which are expected to be similar to those originally proposed by the International Maritime Organization in 2004.

The IMO rules, which are generally supported by the maritime industry, call for no more than 10 organisms in a cubic meter of water. When originally drafted, the technology to accomplish that target was limited. Although the standards have still not been ratified by enough nations (including the U.S.) to enforce them, manufacturers around the world have developed technology that does meet the standards.

Costs are expected to be about $1 million per ship for each of the approximately 68,000 ships that would be covered under the new rules, Richardson said. “The good news is that the outlook is promising in that the technology is available, tested and cost-effective.”

The new systems use diverse technology ranging from filtration and deoxygenation to environmentally friendly biocides that are produced onboard from seawater without the addition of chemicals. As of 2011, 34 ballast water management systems have received basic approval and 20 systems have received final approval. Over time, as the technology continues to improve, the Coast Guard expects to implement standards that are 10 times more strict.


Until recently, open-ocean exchange was the only approved method of treating ballast water. It removes many of the estuarian organisms that could become problematic in another low-salinity habitat. Water taken on in open water is less likely to contain organisms that could survive in a coastal ecosystem.

Open-water exchange, however, is only about 90% effective because not all water can be pumped out of ballast tanks and some organisms can accumulate in the bottom of the tank. An FWRI study conducted between 2003 and 2006 sampled ballast water on 63 ships that were primarily bulk cargo carriers from Central and South America, Europe, the Mediterranean and the Pacific northwest.

Results included:

• 36% of ships and 42% of tanks had live algae
• 9 nonnative species were found
• 83 species were recorded
• 1 nonnative harmful species (Dictyocha fibula) was found.
Cysts (resting stage of microalgae) also were abundant in ballast water:
• 39% of ships and 46% of tanks contained cysts
• Some samples contained more than 400 individual cysts
• 2,969 cysts were isolated and incubated
• 21% germinated
• Two potentially nonnative species were established in culture

Along with the non-native organisms, a native but harmful dinoflagellate, Alexandrium balechii, was collected and cultured from the same vessel six months apart, indicating that ships picking up ballast water in Tampa Bay may transport a harmful organism to other coastal areas with similar ecologies.

Originally published Winter 2012

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