June 8, 2012
Tsunami Debris Could Harbor Invasive Species
While the 70-foot-long dock that washed ashore at an Oregon beach earlier this week may not be radioactively harmful or contain chemical contaminants, scientists are warning that it is likely home to a different sort of threat.
The dock, which was dislodged from a fishing port in northern Japan by the 2011 earthquake and tsunami, floated across the Pacific Ocean and arrived at Agate Beach, a mile north of Newport, on Tuesday.
On Thursday, scientists at the Oregon State University (OSU) Hatfield Marine Science Center warned that the dock is home to potentially invasive biological species.
In fact, according to a university press release, those experts noted that the debris is home to approximately 13 pounds worth of organisms per square foot, or approximately 100 tons in all.
Through Thursday, they reported having already obtained samples of at least four different species of barnacles, starfish, urchins, anemones, algae, and other forms of marine life.
“This float is an island unlike any transoceanic debris we have ever seen,” OSU Marine Invasive Species Specialist John Chapman said in a statement.
"Nearly all of the species we´ve looked at were established on the float before the tsunami; few came after it was at sea," he added. "It is as if the float drifted over here by hugging the coasts, but that is of course impossible“¦ Life on the open ocean, while drifting, may be more gentle for these organisms than we initially suspected."
Chapman explained that invertebrates such as those found on the dock can live for months without food. Even so, he called it "surprising" and "mind-boggling" that the lifeforms had managed to survive the journey from Japan and across the ocean to the United States.
OSU Marine Ecologist Jessica Miller reported that a type of brown algae known as wakame was spotted on a majority of the dock. Wakame is native to the western Pacific Ocean in Asia, she said, and while it had invaded southern California, it had not been reported in the northern half of the state.
"This is something we need to watch out for," she said, pointing out that the Oregon Department of Fish and Wildlife and Oregon State Parks and Recreation Department planned to scrape the dock and bag the biological material they find in order to help limit the spread of non-native lifeforms.
Even so, she said that there was no way for scientists to tell whether or not some species had already been deposited in the waters near the shoreline.
"We have no evidence so far that anything from this float has established on our shores," Chapman said. "That will take time. However, we are vulnerable“¦ We hope that none of these species we are finding on this float will be among the new discoveries in years to come."
According to the press release, the researchers say that it is "difficult to assess how much of a threat the organisms on the newly arrived float may present," and that additional debris that could wash ashore in the future could also bring other invasive species with them.
"However," they add, "this dock may be unique in that it represents debris that has been submerged in Japan and had a well-developed subtidal community. This may be relatively rare, given the amount of debris that entered the ocean, the researchers say."