Imagine if millions of gallons of seawater teeming with invasive organisms found its way into Puget Sound daily, endangering native species and altering the ecosystem. Sound preposterous? Far-fetched? Unconscionable?
It’s true. On average, 2.5 billion gallons of ballast water, roughly nine times the volume of the Tacoma Dome, are discharged into Washington waters annually. Two-thirds of this volume is dumped into Puget Sound.
The introduction of invasive species to the United States poses a serious threat to local species and ecosystems, according to Puget Sound Partnership, a state agency for Puget Sound restoration and protection. Aquatic invasive species are often introduced via ballast water, which is used by shipping vessels for stability, and later discharged at ports to load cargo.
According to the Washington State Aquatic Nuisance Species Program (ANS), seven of the nine species deemed particularly troublesome are thought to be introduced through ballast water.
To stop the influx of non-native species, the Washington Department of Fish and Wildlife is working with neighboring coastal states and the U.S. Coast Guard to create a uniform standard for ballast water treatment.
As ships leave their port of origin, operators pump water into the ballast tanks of the vessel to maintain stability. These tanks, which can hold thousands of gallons of water, also serve as cargo space when emptied.
On the open ocean, improperly balanced ships can capsize during rough weather, especially if the ship isn’t carrying cargo. Ballast water in the hull balances the ship and also helps with propulsion and maneuverability.
Once the ship reaches calmer waters or a port to load cargo, operators discharge, or ‘deballast’, the tanks, effectively dumping water and sediments rich in non-native species into a foreign ecosystem.
Puget Sound’s ports are important centers of commerce, receiving ships laden with goods from all corners of the earth and exporting Washington’s various commodities.
In 2005, more than 4,000 ships carrying 62 million metric tons of imported and exported goods passed through Washington ports, according to the U.S. Maritime Administration.
"It’s widely known that ships bring invasive species every day into Puget Sound through their ballast water," said Dr. Russell P. Herwig, research associate professor and marine ballast water specialist at the University of Washington.
In Puget Sound more than 40 documented non-native plant and animal species have been introduced through ballast water. Non-native species of plankton, which are minute organisms suspended in water, frequently show up in the Sound but are extremely difficult to monitor, Herwig said.
Two highly adaptive crab species could wreak serious havoc in Puget Sound if introduced, according to the ANS.
The European green crab, Carcinus maenas, and the mitten crab, Eriocheir sinensis, likely reached the coast of Washington in ballast water but have yet to appear in Puget Sound, Herwig said.
Crab larvae go through a planktonic stage in which they are water-borne, and this is probably how these crabs were shipped to Washington, he said.
European green crabs are voracious foragers, preying heavily on bivalve shellfish such as oysters and mussels. They also feast readily on juvenile Dungeness crabs, who occupy the same intertidal zone. Dungeness crabs represent a multi-million dollar commercial and recreational industry in Washington, according to the Puget Sound Partnership.
The mitten crab takes a different tack towards destruction. Tolerant of lower salinities, this crab burrows in estuarine areas and erodes the shoreline. It could potentially meander into Columbia River tributaries, eroding riverbanks and eating salmon, trout and sturgeon eggs.
Determining the impact of invasive species can be tricky, Herwig said. Sometimes non-indigenous species out-compete native animals for nutrients, essentially starving them. This sort of gradual assimilation can persist for years before biologists take notice.
"Another problem with invasive species is that there are often no natural predators," Herwig said. Without predation, some invasive species can reproduce exponentially, displacing native species by sheer volume.
Attempts to remove invasive infestations are often futile.
"It’s like trying to find a needle in a haystack," Herwig said. "There are so many miles of coastline [in the Puget Sound]. It’s almost impossible to track down and eradicate an invasive species once it’s been introduced."
The treatment of ballast water offshore is a widely accepted method to prevent invasion. The most common practice is mid-oceanic exchange, where a ship deballasts in the open ocean and refills with water before coming into port. This procedure exposes ballast-borne organisms to a variety of inhospitable conditions.
"Coastal species often won’t survive in the open ocean," said Dr. David H. Shull, marine biologist and professor at Western Washington University. "Salinity, food resources and various aspects of their lifestyle are incompatible with conditions in the open ocean."
Likewise, open-ocean species do not fare well in coastal waters.
Differences in salinity and food resources may kill the majority of organisms in the tanks, but mid-oceanic exchange isn’t 100 percent effective, Shull said.
"Estuarine organisms, organisms that inhabit an estuary, can be exposed to widely fluctuating salinities," Shull said. "These organisms, as well as animals that can live inside the hull of a ship, could still survive the exchange."
Also, mid-oceanic exchange doesn’t completely empty the ballast tanks; pumps in the hull of the ship weren’t designed for such a procedure.
Water and sediment often build up inside the tanks even after exchanges, said Dan Stahl, Director of Marine Services at the Port of Bellingham.
As a cadet in the Navy, one of Stahl’s duties included mucking out the tanks with a hose.
"I was knee-deep in mud, and there were these white crabs who hadn’t seen the light of day in weeks," Stahl said. "Those crabs were thriving in there."
The shortcomings of mid-oceanic exchanges are well known in the shipping industry.
Mid-oceanic exchange is an imperfect solution, said Eric Johnson of the Washington Public Port Association.
Doing an exchange on a large vessel like an oil tanker can take an entire day, Johnson said. The tanks have to be emptied and refilled in a certain order to keep the ship balanced at all times. This is dangerous both for the crew and a ship itself, which isn’t made to withstand such tremendous structural stress.
New technology for ballast treatment, such as ultraviolet sterilization, is promising, Johnson said. As water fills the tanks, it’s channeled through a UV sterilizer that subjects any organisms inside to potent ultraviolet radiation. UV sterilizers effectively destroy a wide range of organisms but are extremely expensive.
Retrofitting one oil tanker with an UV system can cost close to $1 million, Johnson said.
Until the U.S. Coast Guard requires all ships to have on-board treatment systems, mid-oceanic exchanges will be the only federally regulated treatment, Johnson said.
The U.S. Coast Guard requires all vessels to perform a mid-oceanic exchange before crossing the Economic Exclusion Zone (EEZ), which lies 200 nautical miles offshore of the U.S. coast. Ship operators are required to allow Coast Guard officers to board the vessel and monitor the exchange. Operators are also required to fill out a ballast exchange report that is kept with the ship at all times.
The Coast Guard only regulates mid-oceanic traffic, not coastal traffic, which occurs inside the EEZ. Also, the Coast Guard only checks the salinity of the ballast water to verify that it’s been exchanged, and this isn’t enough, Herwig said.
"Salinity by itself isn’t a good indicator," Herwig said. "Water in ports tends to have lower salinity than open ocean water, but that’s not always the case."
Alternate methods of evaluating whether ballast water has been exchanged are being developed, Herwig said. One idea is to identify chemical signatures in coastal water that don’t exist in the open ocean and test for these differences.
To supplement the Coast Guard’s regulations, Washington requires ballast exchanges 50 nautical miles before coastal traffic reaches port. Ship operators are required by state law to log their exchanges or to retain their ballast. Coastal traffic mainly includes ships from Alaska, Oregon and California.
According to the Puget Sound Partnership, 90 percent of the ballast water discharged into Washington ports in 2005 underwent mid-oceanic exchange. Although this percentage is impressive, just a single non-compliant vessel carrying the wrong species is enough to start an invasion.
In 2005, nearly 12 million gallons of un-exchanged ballast water were discharged into Puget Sound, with more than 95 percent of it originating in California, according to the Puget Sound Partnership.
Monitoring ballast water from California is one of Puget Sound’s primary concerns, Herwig said. Many of the destructive non-native species from Asia and Europe are already established in Californian ports, including green and mitten crabs.
During lengthy overseas voyages, many planktonic organisms perish in ballast tanks, meaning a higher percentage of organisms will likely survive the short trip between California and Washington, Herwig said.
Existing populations of non-native species in Puget Sound are probably here to stay. But, in order to prevent potentially devastating invasions from neighboring coastal states, more stringent regulations must be implemented for traffic within the EEZ.
If the U.S. Coast Guard were to regulate both coastal and mid-oceanic traffic exchanges, ship operators on coastal vessels would face increased pressure to obey the law, Herwig said. In addition to the mid-oceanic exchange requirements, 200 nautical miles out by the Coast Guard and 50 nautical miles out by the state of Washington, heavy fines could be imposed upon vessels that violate exchange regulations.
Ballast water is only one of several possible entryways for invasive aquatic species to reach Puget Sound. By strictly regulating ballast treatment, especially from high-risk areas like California, the Washington Department of Fish and Wildlife strives to minimize the likelihood of future invasions.
According to the Puget Sound Partnership, the San Francisco Bay area is home to more than 234 non-native plant and animal species, most likely introduced by ballast water. These invaders account for up to 99 percent of the total biomass in the Bay.
Now picture the Puget Sound, with its fragile ecosystems and diverse denizens, silently succumbing to a wave of foreign invaders. The takeover will be imperceptibly slow and utterly irreversible. Familiar species could give way to these encroaching hordes, transforming the very nature of the Sound.