This is the first report of long-distance transoceanic dispersal of coastal, shallow-water benthic foraminifera by ocean rafting, documenting survival and reproduction for up to four years. Fouling was sampled on rafted items (set adrift by the Tohoku tsunami that struck northeastern Honshu in March 2011) landing in North America and the Hawaiian Islands. Seventeen species of shallow-water benthic foraminifera were recovered from these debris objects. Eleven species are regarded as having been acquired in Japan, while two additional species (Planogypsina squamiformis (Chapman, 1901) and Homotrema rubra (Lamarck, 1816)) were obtained in the Indo-Pacific as those objects drifted into shallow tropical waters before turning north and east to North America. Four species were acquired after the debris came ashore in Hawaii and in North America. As previously shown for the Japanese species Trochammina hadai Uchio, 1962 and the Indo-Pacific species Amphistegina lobifera Larsen, 1976, introduced foraminiferal species may rapidly proliferate and disperse, negatively impacting native species. In the geologic past, panoceanic rafting must have been relatively infrequent, as it would have floating pumice and vegetation with relatively limited potential for multiyear survival at sea. In modern times, the ever-increasing abundance of floatable plastic artifacts emplaced along tectonic coastlines provides a greater abundance of more permanent materials for tsunami- and storm-generated rafts that can introduce foraminifera and other marine biota to distant shorelines.

Twelve species of sponges (Calcarea and Demospongiae) were found on Japanese Tsunami Marine Debris (JTMD) that washed ashore in Oregon, Washington, and Hawai‘i. All taxa but one determined to species level are amphi-Pacific, with three having type localities in California (Leucosolenia eleanor Urban, 1906, Hymeniacidon sinapium de Laubenfels, 1930, and Mycale macginitei de Laubenfels, 1930). Haliclona xena de Weerdt, 1986, known previously only from western Europe (and where it is regarded as introduced from an unknown region) is here newly reported from the Tohoku coast of Honshu, as is Halisarca “dujardini Johnston, 1842”. Five species (Mycale macginitei, Hymeniacidon sinapium, Ute sp., Haliclona xena and Halisarca “dujardini”) were observed only once. Multiple lines of evidence (including lack of colonization by uniquely Eastern Pacific sponge species, the arrival in Hawai‘i of some of the same species whose only possible origin was Japan, and the low probability of coastal sponge larvae colonizing JTMD in the open ocean) indicate that the sponges on JTMD originate from the Western Pacific. Several species of sponges may have completed multiple generations on these long-distance rafts.

Twenty-eight species of hydroids are now known from Japanese tsunami marine debris (JTMD) sent to sea in March 2011 from the Island of Honshu and landing between 2012 and 2016 in North America and Hawai‘i. To 12 JTMD hydroid species previously reported, we add an additional 16 species. Fourteen species (50%) were detected only once; given the small fraction of debris sampled, this suggests that the diversity of the total arriving hydroid fauna was likely larger. Our ongoing studies provide the first documentation of these species being rafted from one continental margin to another. Plumalecium plumularioides (Clark, 1877) is newly reported for the Japanese hydroid fauna. Fourteen species (52%), held to be either naturally amphi-Pacific or possibly introduced by ships at some earlier date, were already known from the Pacific coast of North America. We suggest that Obelia griffini Calkins, 1899, as represented in the JTMD fauna, may be a North Pacific oceanic neustonic species. We propose that Hydrodendron mirabile (Hincks, 1866) and its congeners be included in the family Phylactothecidae Stechow, 1921, here emended. We establish a new family, Plumaleciidae Choong and Calder, 2018, to accommodate the genus Plumalecium Antsulevich, 1982.

Floating maritime objects torn from their anchorage by the March 2011 Tōhoku tsunami transported Japanese near-shore biota to the Pacific coast of North America and the Hawaiian Islands. This Japanese tsunami marine debris (JTMD) biota included five species of chitons: Mopalia seta Jakovleva, 1952, Placiphorella stimpsoni (Gould, 1859), Acanthochitona achates (Gould, 1859), Acanthochitona rubrolineata (Lischke, 1873), and an undescribed species with close affinities to Acanthochitona defilippii (Tapparone-Canefri, 1874), here referred to as Acanthochitona sp. A. The last of these was the most common chiton on the tsunami debris. Our identifications are supported by morphological characters and analyses of mitochondrial 16S and COI gene sequences from the retrieved specimens, supplemented by new samples of North West Pacific specimens. A. rubrolineata, a former synonym of A. achates, is here revived as a valid species; it is, surprisingly, weakly supported as having close affinities to an Hawaiian endemic chiton, A. viridis (Pease, 1872).

The Tohoku tsunami of March 2011 ejected a vast amount of debris into the Pacific Ocean. Wood boring shipworms (Bivalvia: Teredinidae) were either already present in, or settled on, the wooden fraction of this debris, offering a unique opportunity to study shipworm diversity in rafted wood of a known origin and time of ocean entry. Lumber and other wood began appearing on Central Pacific (Hawaiian Islands) and Eastern Pacific beaches in 2013. Eighty pieces of wood Japanese Tsunami Marine Debris (JTMD) consisting of construction beams, trees, milled logs, and wood from vessels or maritime structures were analyzed. Six shipworm species resident in the coastal waters of Japan were found: Bankia bipennata (Turton, 1819), Bankia carinata (Gray, 1827), Teredothyra smithi (Bartsch, 1927), Psiloteredo sp., Lyrodus takanoshimensis (Roch, 1929), and Teredo navalis Linnaeus, 1758. Two pelagic species, Teredora princesae (Sivickis, 1928) and Uperotus clava (Gmelin, 1791), were acquired by JTMD wood in the transoceanic voyage. Several of these wood items were discovered soon after stranding and contained live shipworms. Up to five shipworm species were found in any one wooden object. The present work represents the first study of the diversity and abundance of shipworms transported across an ocean basin in a large woody debris field.

The family Teredinidae (shipworms) contains 70-plus species of boring bivalves specialized to live in and digest wood. Traditional means of species identification and taxonomy of this group encounter numerous challenges, often compounded by the diverse and dynamic nature of shipworm ecology and distribution. Modern integrative taxonomic methods are shedding new light on this complex group, from delineating cryptic species to resolving phylogenetic relationships within the family. This study reported new sequence data from shipworm species rafted from the western to eastern Pacific Ocean in woody marine debris resulting from the Japanese tsunami of 2011. Eight species of shipworms were found in this debris and tissue from five species was collected. Partial nuclear ribosomal 18S rRNA gene sequences were obtained from Bankia bipennata (Turton, 1819), Bankia carinata (Gray, 1827), Psiloteredo sp., Teredora princesae (Sivickis, 1928), and Teredothyra smithi (Bartsch, 1927). A 658 base pair fragment of COI was successfully sequenced from Psiloteredo sp. and T. princesae specimens from tsunami debris, as well as Psiloteredo megotara (Hanley, 1848) from Europe and Nototeredo norvagica (Spangler, 1792) from Scandinavia. Psiloteredo sp. is very similar morphologically to the North Atlantic Ocean P. megotara; however, these two species are genetically distinct with a 12.8% K2P distance in their COI sequences. The transport of shipworms across the North Pacific Ocean in woody debris generated by a tsunami shows that major geologic events can connect previously isolated geographic areas and provide the opportunity for the establishment of invasive species and subsequent speciation.

Six families and at least 15 species of harpacticoid copepods were found on debris, generated from the earthquake and tsunami that struck Japan on 11 March 2011, that landed in North America. Harpacticoids occurred on a wide variety of objects, ranging from small plastic items to a massive floating dock. At the genus level, the harpacticoid copepod assemblage was similar to that found with floating algae by previous authors. Two of the species identified — Harpacticus nicaeensis Claus, 1866 and Dactylopodamphiascopsis latifolius (G.O. Sars, 1909)—are not previously known from the eastern Pacific Ocean. Six of the species are cosmopolitan or amphi-Pacific in distribution. None of the species were originally described from Japan, and some may have been acquired after the debris had left the Japanese coast, either from floating algae at sea or near the North American coast. Interpretation of the original source of the harpacticoids is difficult because regional taxonomic knowledge is lacking, especially for outer coast habitats where most of the tsunami debris was deposited. Identifying the harpacticoid sources is also complicated by many unresolved species complexes in the group—five of the taxa found were either very similar to or identified as species that taxonomists have regarded to be part of species complexes. Despite these difficulties, decreases over time in copepod diversity, in the frequency of unique species, and in the number of species per object, all suggest that many species were acquired in Japanese coastal waters.

We report the first direct evidence for the transoceanic transport of living marine Ostracoda. Seven benthic, phytal species, Sclerochilus verecundus Schornikov, 1981, Sclerochilus sp. 1, Sclerochilus sp. 2, Obesostoma cf. setosum (Okubo, 1977), Obesostoma sp., Paradoxostomatidae sp., and Xestoleberis setouchiensis Okubo, 1979, were transported in tsunami debris that departed the Japanese coast in March 2011 amongst the biofouling on docks, vessels, and buoys that subsequently landed on the Pacific coast of North America. Remarkably, X. setouchiensis survived more than four years rafting through the North Pacific, with a living specimen still arriving in April 2015. Marine debris in general, and tsunami debris specifically, adds to the long list of vectors by which species may be transported globally.

Forty-nine species of Western Pacific coastal bryozoans were found on 317 objects (originating from the Great East Japan Earthquake and Tsunami of 2011) that drifted across the North Pacific Ocean and landed in the Hawaiian Islands and North America. The most common species were Scruparia ambigua (d’Orbigny, 1841) and Callaetea sp. Of 36 bryozoans identified to species level, 15 are already known from North America, one of which (Schizoporella japonica Ortmann, 1890) is an earlier introduction from Japan; 18 species are known only from the Western Pacific, one of which (Bugula tsunamiensis McCuller, Carlton and Geller, 2018) is newly described in a companion paper. The 13 additional bryozoans, not taken to species level, are likely derived from the Western Pacific based upon evidence reviewed here; two of these species (Callaetea sp. and Arbocuspis sp.) are undescribed. Seven warm-water species, Metroperiella cf. biformis (Zhang and Liu, 1995), Celleporaria brunnea (Hincks, 1884), Drepanophora cf. gutta Tilbrook, Hayward and Gordon, 2001, Smittoidea spinigera (Liu, 1990), Biflustra grandicella (Canu and Bassler, 1929), Biflustra irregulata (Liu, 1991), and Celleporina cf. globosa Liu, 2001, not known from Japan, may have been acquired by Japanese Tsunami Marine Debris (JTMD) as these objects were carried by ocean currents into more southern waters. Three oceanic bryozoans (Jellyella tuberculata (Bosc, 1802), Jellyella eburnea (Hincks, 1891), and Arbopercula angulata (Levinsen, 1909)) provide insight into the routes that some JTMD items may have taken, and thus the conditions experienced, as they rafted from the Western Pacific to the Central and Eastern Pacific. The cooler-water species J. tuberculata and A. angulata were found primarily on JTMD objects arriving in the Pacific Northwest, whereas J. eburnea was most common on objects landing in the Hawaiian Islands. The most common bryozoan growth forms on these rafted objects were runners (creeping uniserial morphology) and arborescent forms capable of using available surface area provided by other organisms (such as hydroids) on space-limited objects. Species that form flat or mounded encrustations were less frequent, suggesting that they do not fare as well in a potentially space-limited environment.

A new species of the cheilostome bryozoan genus Bugula Oken, 1815, Bugula tsunamiensis, is described from Japan, having rafted across the North Pacific Ocean on numerous objects released into the ocean by the 2011 Great East Japan Earthquake and Tsunami, and landing in the Hawaiian Islands and on the Pacific Coast of the United States. This is the second species of the Bugula uniserialis Hincks, 1884 group to be reported from Japan. We elevate the Japanese species Bugula scaphoides constricta Yanagi and Okada, 1918 to full species status, B. constricta, based upon distinctions from the stem species. We suggest that Bugula uniserialis reported from the Galapagos Islands is an undescribed species.

The devastating tsunami of March 2011 on the Pacific coast of Japan produced abundant marine debris which drifted across the Pacific Ocean to North America. Here we document rafting of the Japanese yellowtail jack Seriola aureovittata Temminck & Schlegel, 1845 (Carangidae) across the North Pacific inside a tsunami-generated derelict vessel. Long-distance transport of rafted fish may be an infrequent but potentially consequential mechanism for the introduction of invasive fish, especially given the increasing volumes of debris in the world’s oceans.

The Western Pacific Ocean barred knifejaw Oplegnathus fasciatus was found from 2013 to 2015 along the Pacific Coast of North America from Washington to California. The knifejaw was found in derelict vessels that had arrived on the Pacific Coast and that had been lost during the March 2011 Great Japan Earthquake and Tsunami. Knifejaw were also found free living in the wild in regions known to have received Japanese tsunami marine debris. No previous records of O. fasciatus are known east of the Hawaiian Archipelago.