That worries scientists who fear invasive species could become pests on the coast of the United States and Canada, Yomiuri Shimbun reported. More than 90 species were counted on a 60-foot pier that made landfall in June in Newport, Ore.
Among the passengers were several species that reproduce quickly, including wakame seaweed and crabs native to Japan. In Oregon, blowtorches were used to cleanse the pier of non-native species.
Samuel Chan, a marine ecologist at Oregon State, said invasive species could be especially harmful if they are carried into a bay. The pier landed on a beach on the open coast, but an organism like wakame seaweed could wreak havoc in a closed ecosystem.
Experts also say the debris that has washed up so far is just a taste of what is to come. They predict much more will arrive this winter, including the remains of houses washed out to sea by the tidal wave.
Environmental groups from both sides of the Pacific met in August at a conference in Oregon to discuss the debris problem. One measure they discussed was setting up cameras like those already in use in Japan along the U.S. and Canadian coasts to monitor debris.