The March 11, 2011, tsunami and earthquake that left at least 15,000 dead in Japan is likely to pose hazards to wildlife and the environment of the Pacific coast for at least the next two years if not longer. A 20-meter (about 65 feet) dock washed up at Agate Beach in Newport, Oregon on June 5, after floating more than 7,000 kilometers (about 4,350 miles) from northwestern Japan’s port of Misawa.
Initially, some residents of Newport suggested using the dock to replace wooden docks washed out in a winter storm. But workers from the Ballard Diving and Salvage company will be cutting up the huge structure into five pieces. While one small piece will be used in a memorial to those who died in the tsunami, most of the dock must be disposed to protect against the possible spread of invasive animal and plant species.
When scientists from Oregon State University examined the 150-ton dock, they found that more than 90 different species of seaweed, molluscs and other marine organisms had survived for a 15-month trans-oceanic journey. Three species in particular could colonize local areas and threaten native wildlife:
- the Northern Pacific seastar, which has a huge appetite and can prey on native species; its larvae can be transported to new locations via the ballast of ships so it is particularly difficult to eliminate.
- the Japanese shore crab which, because it reproduces several times a year, can quickly outnumber native crabs; it also feeds on the larvae of lobsters and has posed a threat to ecosystems on the east coast.
- Wakame kelp, which is on the list of the 100 worst invasive species around the world as it can grow in large beds blocking out sunlight for other organisms and interfere with the operation of “docks, ship hulls, nets, fishing gear, moorings, ropes.”
The Japanese government has estimated that about 5 million tons of debris was washed into the ocean by the tsunami and that about 70 percent sunk into the ocean. But about 1.5 million tons are still floating and, as evidenced by the dock, posing environmental hazards whose effects are only beginning to be felt.
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