A 9.0 magnitude quake rocked Japan on March 11, 2011, causing a massive tsunami that rose 125 feet over the country's coast on the same day.
Worms, hydroids including sea anemones and jellyfish, crustaceans and bryozoans which have the habit of colonizing in the underwater beds were also found among the new guest species.
This unprecedented migration was made possible by the natural disaster and a very modern problem - plastic waste and other debris floating in the sea were used to hitch rides on by the marine species.
Almost two-thirds of the species had never been seen on the west coast of the USA, the study said. Researchers are still finding new species 6 years after the wave.
Six years later, scientists are still finding all types of debris washed along the shores of Hawaii and the US west coast.
The team believes they may have found just a fraction of the species that actually washed ashore along the US, since many pieces of debris were cleared away before any analysis or census began.
"When we first saw species from Japan arriving in OR, we were shocked". They note that manmade and natural debris are vastly different, with the latter largely consisting of short-lived, dissolvable, or decomposable materials, such as biodegradable vegetation, that rarely survive a trip across whole oceans. By 2025, that number could be 10 times as much. The coastal damage resulted in millions of objects, ranging in size from small plastic fragments to fishing vessels and large docks, being carried into the Pacific Ocean.
"I didn't think that most of these coastal organisms could survive at sea for long periods of time", said Greg Ruiz, a marine biologist at the Smithsonian Environmental Research Center, who co-authored the study. They say it is too early to tell how numerous species will take root and push out native species.
Storms severity is expected to increase as the climate change continues, and so could instances of these weather events creating ocean-going rafts that spread invasive species. They were swept all the way from Japan after the 2011 tsunami.
It is not clear if the new arrivals will have any effect on native species, since such impacts often take years to assess.
"There is huge potential for the amount of marine debris in the oceans to increase significantly", said lead author James Carlton, an invasive species expert with the Maritime Studies Program of Williams College and Mystic Seaport in CT.