in ship ballast
Date: July 22, 1997
VALDEZ, Alaska--Small creatures that could cause big problems for Alaska's environment may be hiding in the murky ballast tanks of oil tankers.
The danger is from so-called alien species--the crabs, fish and other creatures not native to Alaska--that are sucked up with seawater into the ballast tanks of oil tankers bound for Alaska. Such stowaways could wreak havoc on the marine environment when the ballast is later discharged in state waters, according to Nora Foster, a biologist at the University of Alaska Fairbanks.
"Non-commercial crabs, like green crabs that are causing problems along the West Coast, could out-compete our commercial crab species like Dungeness," said Foster. "Predation on local prey species could potentially cause problems for fish stocks that rely on those prey, and competition for space also could force out some local species."
The Prince William Sound Regional Citizens Advisory Council (RCAC) is concerned that such species already have made their way into the sound.
"Large ships and oil tankers have been referred to as floating aquariums," said Joel Kopp, research coordinator at the RCAC. "The ballast gets discharged into the Port of Valdez. "Most of these creatures will die in their new environment. But of those that do survive, some will probably coexist peacefully with native species, while others may be nuisance species with serious impacts on Alaskan waters."
In an RCAC-funded pilot study that began this spring, researchers from the Smithsonian Environmental Research Center collected water samples from the ballast tanks of oil tankers. While the findings won't be ready until the fall, Anson Hines of the Smithsonian expects to see a variety of species.
"Many different kinds of organisms, both plant and animal, of all major taxonomic groups, are found in ballast water," said Hines. "Fish, crabs, and a number of plankton species and plant species are common. These organisms pass easily through the intakes of some of these ships."
The RCAC recently received a $172,000 grant from the Alaska Sea Grant Program to extend the study for two years. Alaska Sea Grant is a federal-state research agency based at the University of Alaska Fairbanks (UAF). The grant is being combined with funds from the RCAC, the Smithsonian, Alyeska Pipeline Service Company, the U.S. Fish and Wildlife Service, and Oregon State University. The total research budget is about $500,000.
During the two-year study, Smithsonian and UAF scientists will take additional water ballast samples from oil tankers. They'll also test whether the species they find are likely to survive in the cold waters of the sound. Tests to measure the effectiveness of exchanging ballast water while far at sea will be conducted, and a database reference of species found in the ballast tanks will be compiled.
"We decided it's time to look at the ballast water because for 20 years that tankers have been coming here, no one has looked to see what's arriving in the ballast water," said Kopp.
Empty oil tankers returning to Alaska routinely take on ballast water before leaving port. The ballast enhances ship stability during voyages across the Pacific Ocean. Federal law requires tankers coming from foreign ports to exchange ballast water while far at sea, in the belief that foreign species will be flushed into the deep ocean where they likely cannot survive. Tankers coming from other U.S. ports are exempt from the exchange requirement. The RCAC's Joel Kopp said ballast exchanges are not always effective at purging unwanted species.
"Not all of the ballast is exchanged and a lot of the critters just settle to the bottom of the tank," said Kopp. "They could still be discharged into Port Valdez."
Worldwide, the introduction of foreign species is a leading environmental issue. San Francisco Bay, for example, has more than 200 non-native species. Most of the species came to the bay in ships' ballast. Elsewhere, non-native species such as European zebra mussels in the Great Lakes have plugged cooling pipes in power utilities, causing millions of dollars in damage.
At least one alien species--a type of soft-shelled clam--is known to have established a foothold in Prince William Sound. The clam is thought to have made its way up from California and Oregon to Alaska aboard ships in the 1800s.
The Alaska Sea Grant College Program is a marine research, education and outreach service headquartered at the University of Alaska Fairbanks, School of Fisheries and Ocean Sciences. It is funded by the National Oceanic and Atmospheric Administration in partnership with the state of Alaska and private industry.
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