A few seaweeds, snails, oysters, and other marine life are hitching rides on debris items from the 2011 Japan tsunami which are now washing up in the U.S.

This influx of sea creatures aboard tsunami marine debris is also bringing concerns that some of these foreign species may become invasive, possibly threatening marine life and communities here in the United States.

For example, more than 90 different species [PDF] managed to make the journey (or hitchhike along the way) aboard a single item from Japan—the 66-foot-long dock which washed up near Newport, Ore., and came coated in marine life. Of those 90+ species, eight have been identified as showing up outside the range where they normally live.

This includes a species of Asian kelp known as wakame (Undaria pinnatifida). While wakame is a tasty ingredient in many traditional soups and salads in Japan, the International Union for Conservation of Nature's (IUCN) Global Invasive Species Database also has pegged it as one of the world’s 100 worst invasive species.

If it were to become established along the Oregon or Washington coast, wakame could balloon into huge kelp beds that out-compete native kelp and seaweeds and could also become a nuisance as they attach to ships and other marine infrastructure.

The northern Pacific seastar (Asterias amurensis) and Japanese shore crab (Hemigraspus sanguineus) are two other known invasive species that arrived on the dock in Oregon in June 2012.

Fortunately for Oregon's local marine life, two days after the dock's arrival, the state had workers using shovels and rakes to scrape off invasive species and put them in a deep and sandy resting place, eight feet below the beach’s surface. They then sterilized anything that remained on the dock with a blowtorch.

However, the majority of the species identified on the dock are non-invasive seaweeds and polychaete worms. In fact, most of the species arriving on marine debris are not invasive—even if they are hitchhikers. This was the case at Cape Disappointment, Wash., when a small Japanese fishing boat (with a confirmed connection to the tsunami) washed up covered in gooseneck barnacles (order Pedunculata). While unusual-looking, these barnacles are not invasive and have a fascinating historic myth purporting that barnacle geese developed from gooseneck barnacles because they had similar colors and shapes.

This approximately 20-foot boat washed ashore at Cape Disappointment State Park in Washington as a result of the March 2011 Japan tsunami. It came covered in non-invasive gooseneck barnacles, which are common in the open ocean. (NOAA)

During a recent two-day regional workshop at Portland State University in Oregon, NOAA examined this issue of marine life latching onto and growing on marine debris (a phenomenon known as "biofouling").

Approximately 80 aquatic invasive species experts from federal (U.S. and Canada), tribal, and state government agencies from the West Coast; academic institutions; and non-governmental organizations began developing a regional, science-based approach to biofouling and Japan tsunami marine debris.

How—and who—is best suited to respond to the potential introduction of aquatic invasive species on tsunami debris? How should we communicate with the public about the possible threats these aquatic newcomers may pose? The team is working on finalizing a framework and regional protocols "to identify, detect, and respond effectively and rapidly to marine debris with invasive species" [PDF].

If you are in Oregon and find a piece of marine debris which is hosting marine organisms, take a photo of it and send a detailed description to beach.debris@state.or.us. The state of Oregon has more information about what to do [PDF] and recommends to "never move debris with organisms on it to other bodies of water—an aquarium, pond or estuary. It increases the risk that invasive species will spread."

For those in Washington, the state recommends that "if you find an object you suspect has invasive species, call 1-855-WACOAST (1-855-922-6278) and press '3' to leave a message for state authorities. Be sure to include as much information about the object's location as possible." If you are in Alaska, California, or Hawaii and find marine debris that has living organisms attached, the Aquatic Nuisance Species (ANS) Task Force offers the following instructions:

• Remove the item from the water and place on dry land (above the high tide line) so that any organisms living on it will die and not be returned to the ocean. Never move debris with organisms on it to other bodies of water—an aquarium, pond or estuary. It increases the risk that invasive species will spread.




• Take a photo, if possible, and send photo along with details (location, county, date found, description of item) to DisasterDebris@noaa.gov.




• This information will be shared with the marine debris response team and invasive species experts to determine what action needs to be taken. If we are notified that dock- or pier-sized structures wash ashore, a science-based team of experts may be deployed to the site for immediate evaluation."