Tsunami-driven rafting: Transoceanic species dispersal and implications for marine biogeography

Abstract

The 2011 East Japan earthquake generated a massive tsunami that launched an extraordinary transoceanic biological rafting event with no known historical precedent. We document 289 living Japanese coastal marine species from 16 phyla transported over 6 years on objects that traveled thousands of kilometers across the Pacific Ocean to the shores of North America and Hawai'i. Most of this dispersal occurred on nonbiodegradable objects, resulting in the longest documented transoceanic survival and dispersal of coastal species by rafting. Expanding shoreline infrastructure has increased global sources of plastic materials available for biotic colonization and also interacts with climate change-induced storms of increasing severity to eject debris into the oceans. In turn, increased ocean rafting may intensify species invasions.

Exploring potential establishment of marine rafting species after transoceanic long‐distance dispersal

“…The role of long‐distance dispersal in population expansion is historically difficult to enumerate, but evidence from the Japanese tsunami of 2011 shows that a wide variety of marine organisms are able to survive for years adrift on debris across more than 7,000 km of ocean (Carlton et al, ). As the amount of oceanic debris continues to increase (Eriksen et al, ; Lebreton et al, ), this dispersal mechanism is likely to grow in prevalence and may lead to increased likelihood of species invasions.…”

“…A majority of species were sessile invertebrates ( n = 30), while 16 were mobile invertebrates and two were algae. Carlton et al () used body size as a way to infer ages of debris‐rafting species and excluded species that appeared to be newly settled and were therefore likely to be acquired as floating debris neared the North American coastline. Therefore, this subset of species can be linked directly to marine debris that transited across the Pacific from Japan to the Pacific coast of North America.…”

A new record of Avrainvillea cf. erecta (Berkeley) A. Gepp & E. S. Gepp (Bryopsidales, Chlorophyta) from urbanized estuaries in the Hawaiian Islands

“…Introduction to Hawai‘i as a result of the 2011 Tohoku earthquake and subsequent tsunami in Japan are possible; indeed, studies have recently recorded introduced algal species on tsunami debris on the west coast of North America and in Hawai‘i (e.g. West et al 2016, Carlton et al 2017, Carlton et al 2018, Hanyuda et al 2018). Given the vegetative propagation achieved by members of the Bryopsidales, it is possible that very small fragments were carried to Hawai‘i by one means or another naturally (Hillis-Colinvaux et al 1965, Walters and Smith 1994, Vroom et al 2003, Wright and Davis 2006).…”

Lyrodus mersinensis sp. nov. (Bivalvia: Teredinidae) another cryptic species in the Lyrodus pedicellatus (Quatrefages, 1849) complex

“…Dispersal by driftwood or ships has been long recognised as playing a role in the distribution of this morphospecies (Turner 1966). Rafting adults in driftwood can be transported by currents, particularly after extreme events such as tsunamis (Carlton et al 2017) or storms. Little experimental work has been done, however, to test whether adult teredinids in driftwood can survive and reproduce successfully during rafting.…”