Transoceanic dispersal of terrestrial species by debris rafting

Rare, long-distance dispersal events are a key process in generating and maintaining patterns in biological diversity and species distributions across space and time. The 9.0 magnitude earthquake that struck the eastern coast of Japan in 2011, and the subsequent 38 m high tsunami washed large amounts of shoreline debris into the Pacific Ocean that led to a large-scale biological rafting event carrying nearly 300 marine species to the western shores of North America. Whether oceanic, trans-Pacific dispersal via rafting generates long distance dispersal events for small, flightless, terrestrial species is unknown. By sampling beach debris associated with known hot-spots of tsunami debris along the north and east shores of Graham Island, Haida Gwaii, Canada, I document significantly dissimilar invertebrate communities associated with tide-line beach debris and the occurrence of several putative Japanese species of soil-dwelling mites (Acari: Oribatida). Previous explanations of Haida G...