ArticlePDF Available

Calder, D.R., Choong, H.H.C., Carlton, J.T., Chapman, J.W., Miller, J.A., and Geller, J. 2014. Hydroids (Cnidaria: Hydrozoa) from Japanese tsunami marine debris washing ashore in the northwestern United States. Aquatic Invasions 9: 425-440.

Authors:

Abstract and Figures

Fourteen species of hydroids, including two anthoathecates and 12 leptothecates, are reported from the west coast of North America on debris from the tsunami that struck Japan on 11 March 2011. Six species were found on a dock that stranded at Agate Beach, Newport, Oregon, five from a boat at Gleneden Beach, Oregon, four from a dock in Olympic National Park, Washington, and two from a boat in Grays Harbor, Washington. Obelia griffini Calkins, 1899, the most frequently encountered species, was collected on three of the four derelict substrates. Eight of the species are known to be amphi-Pacific in distribution. Of the rest, at least five (S tylactaria s p . ; Eutima japonica Uchida, 1925; Orthopyxis platycarpa Bale, 1914; Sertularella sp.; Plumularia sp.) are not previously known from the west coast of North America. Hydroids of E. japonica occurred as commensals in the mantle cavity of the mussel Mytilus galloprovincialis Lamarck, 1819. Obelia griffini, O. gracilis Calkins, 1899 (not its secondary homonym Laomedea gracilis Dana, 1846) and O. surcularis Calkins, 1899 are taken to be conspecific. Of the three simultaneous synonyms, precedence is assigned to the name O. griffini under the Principle of the First Reviser in zoological nomenclature. The species is sometimes regarded as identical with O. dichotoma (Linnaeus, 1758).
Content may be subject to copyright.
Aquatic Invasions (2014) Volume 9, Issue 4: 425–440
doi: http://dx.doi.org/10.3391/ai.2014.9.4.02
© 2014 The Author(s). Journal compilation © 2014 REABIC
Open Access
425
Research Article
Hydroids (Cnidaria: Hydrozoa) from Japanese tsunami marine debris washing
ashore in the northwestern United States
Dale R. Calder1*, Henry H.C. Choong2,3, James T. Carlton4, John W. Chapman5, Jessica A. Miller5
and Jonathan Geller6
1,2Invertebrate Zoology Section, Department of Natural History, Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario, Canada, M5S 2C6
3Palaeobiology Section, Department of Natural History, Royal Ontario Museum,100 Queen’s Park, Toronto, Ontario, Canada, M5S 2C6
4Williams College-Mystic Seaport Maritime Studies Program, Mystic, Connecticut 06355, USA
5Department of Fisheries and Wildlife, Hatfield Marine Science Center, Oregon State University, 2030 SE Marine Science Drive, Newport,
Oregon 97365, USA
6Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USA
E-mail: dalec@rom.on.ca (DRC), henryc@rom.on.ca (HHCC), james.t.carlton@williams.edu (JTC), john.chapman@oregonstate.edu (JWC),
jessica.miller@oregonstate.edu (JAM), geller@mlml.calstate.edu (JG)
*Corresponding author
Received: 12 February 2014 / Accepted: 28 May 2014 / Published online: 4 August 2014
Handling editor: Melissa Frey
Abstract
Fourteen species of hydroids, including two anthoathecates and 12 leptothecates, are reported from the west coast of North America on
debris from the tsunami that struck Japan on 11 March 2011. Six species were found on a dock that stranded at Agate Beach, Newport,
Oregon, five from a boat at Gleneden Beach, Oregon, four from a dock in Olympic National Park, Washington, and two from a boat in Grays
Harbor, Washington. Obelia griffini Calkins, 1899, the most frequently encountered species, was collected on three of the four derelict
substrates. Eight of the species are known to be amphi-Pacific in distribution. Of the rest, at least five (Stylactaria sp.; Eutima japonica
Uchida, 1925; Orthopyxis platycarpa Bale, 1914; Sertularella sp.; Plumularia sp.) are not previously known from the west coast of North
America. Hydroids of E. japonica occurred as commensals in the mantle cavity of the mussel Mytilus galloprovincialis Lamarck, 1819.
Obelia griffini, O. gracilis Calkins, 1899 (not its secondary homonym Laomedea gracilis Dana, 1846) and O. surcularis Calkins, 1899 are
taken to be conspecific. Of the three simultaneous synonyms, precedence is assigned to the name O. griffini under the Principle of the First
Reviser in zoological nomenclature. The species is sometimes regarded as identical with O. dichotoma (Linnaeus, 1758).
Key words: amphi-Pacific distributions, Anthoathecata, anthropogenic debris, invasive species, Leptothecata, northeastern Pacific, Oregon,
population connectivity, transoceanic dispersal, Washington state
Introduction
The widespread geographic distribution of many
hydrozoan species is often attributed to long-
range dispersal by two passive mechanisms, namely
shipping and transport by ocean currents (Ralph
1961). Other species of the group are believed to
have been co-introduced on substrates such as
commercial fisheries resources (notably oysters),
aquatic plants, and organisms in aquaria (Edwards
1976; Dumont 1994). As for shipping, hydroids
can be transported over great distances as part of
fouling assemblages on hulls (Millard 1959; Watson
1985; Mills et al. 2007), or as hydromedusae, or
polyps attached to debris, in ballast water (e.g.
Calder and Burrell 1969; Mills and Sommer
1995). Most long-distance dispersal of hydrozoan
species, however, seems likely to have been
accomplished over extended periods of time by
rafting of sessile hydroid stages on floating natural
substrates (such as seaweeds and logs) carried in
ocean currents and eddies, and by attachment to
wide-ranging nektonic vertebrates and even
planktonic organisms such as pteropods (Cornelius
1981, 1992a, b; Jokiel 1989; Calder 1993).
Modern-day oceanic rafting has been dramatically
altered by the addition of anthropogenic non-
biodegradable floating materials to the open sea,
thus potentially providing substrates capable of
lasting far longer in the ocean than most natural
D.R. Calder et al.
426
substrates. These materials, now a significant
environmental menace in oceans of the world,
provide rafting opportunities for hydroids (Carpenter
and Smith 1972; Gregory 2009). Large anthropo-
genic debris resulting from natural events such as
earthquakes and tsunamis, including dislodged
floating docks and boats, may be significant rafting
substrates as they can transport diverse and
substantial benthic communities over vast distances.
It has been shown that rapid, large-scale transport
of suitable substrates (e.g. pumice rafting in the
Pacific Ocean) fundamentally changes the dispersal
range and limitations for many marine taxa,
particularly those with short pelagic larval stages
or where larval supply or larval behavior may be
limiting factors in dispersal (Bryan et al. 2012).
We report herein on hydroids collected as part
of fouling assemblages from floating derelict
docks and boats carried across the Pacific Ocean
from northern Japan to the west coast of the
United States following the catastrophic Tōhoku
earthquake and tsunami of 2011. This report follows
an earlier account of a western North Pacific
leptothecate hydroid (Sertularella mutsuensis
Stechow, 1931) found on a derelict dock from
Misawa, Honshu, that came ashore in June 2012
on Agate Beach, Newport, Oregon (Choong and
Calder 2013). Since that report, additional
material has been recovered from the substantial
fouling biomass on that dock, from another dock
from Misawa that washed ashore near Mosquito
Creek, Olympic National Park, Washington, and
from two derelict tsunami-generated boats that
stranded on shores of the northwestern United
States. A taxonomic account is provided of two
anthoathecate and 12 leptothecate hydroid species,
at least five of them not previously known from
North America. Live coenosarc was observed in
specimens of all 14 species.
Materials and methods
Hydroids examined here were collected from the
coast of the northwestern United States on
stranded debris from the Tōhoku earthquake and
tsunami that struck Japan on 11 March 2011.
Major substrates, collectors, and dates of collection
included (1) a floating dock at Agate Beach,
Newport, Oregon (coll. JW Chapman and JA
Miller, 05 and 06 June 2012, Japanese Tsunami
Marine Debris [JTMD] bio-fouling registry number
JTMD BF-1), (2) a floating dock at Mosquito
Creek, Olympic National Park, Washington (coll.
JW Chapman and JA Miller, 21 December 2012,
JTMD BF-8), (3) a derelict boat in Grays Harbor,
Washington (coll. J Schultz and A Pleus, 28
December 2012, JTMD BF-12), and (4) a derelict
boat at Gleneden Beach, Lincoln County, Oregon
(coll. JW Chapman and JA Miller, 06 February
2013, JTMD BF-23).
The two docks (JTMD-BF-1 and JTMD-BF-8)
were identified as originating from the Tōhoku
tsunami of 11 March 2011 based on an identification
plaque and on registry numbers. These markings
confirm that they were lost during the tsunami
from the Port of Misawa, Aomori Prefecture, on
the northeast coast of Honshu, Japan. The two
skiffs or pangas (JTMD-BF-12 and JTMD-BF-
23), while having lost names and numbers, were
confirmed as Japanese tsunami debris by (1)
their identical match to other tsunami-generated
Japanese vessels that have washed ashore with
registration numbers, confirming loss of the latter
on 11 March 2011, (2) by maritime historical
evidence that no such vessels landed prior to the
tsunami on the Pacific coast of North America or
Hawaii, and (3) by having species on both of them
that are native to the western Pacific (including
the mussel Musculus cupreus (Gould, 1861), the
barnacle Megabalanus rosa (Choi, Anderson and
Kim, 1992), the isopod Ianiropsis serricaudis
(Gurjanova, 1936), the amphipod Caprella mutica
Schurin, 1935, the nemertean Oerstedia dorsalis
(Abildgaard, 1806), and the bryozoan Tricellaria
inopinata d’Hondt and Occhipinti Ambrogi, 1985).
While the exact origin of the two vessels is not
known, they likely originated in Fukushima or
Aomori Prefectures based on the identified sources
of other JTMD landings in North America during
2012 and 2013 (JT Carlton, unpublished data).
Specimens, fixed and preserved in 95% ethanol,
have been deposited in collections of the Inverte-
brate Zoology Section, Department of Natural
History, Royal Ontario Museum (ROMIZ). The
classification and implied relationships of hydroids
adopted herein generally follows Schuchert (2012)
for anthoathecates and Leclère et al. (2009) for
leptothecates.
Systematic account
Order Anthoathecata Cornelius, 1992a
Family Bougainvilliidae Lütken, 1850
(?) Bougainvillia muscus (Allman, 1863)
(Figure 1a)
Eudendrium ramosum.–Van Beneden, 1844b: 56,
pl. 4, figures 1–13 [not Eudendrium ramosum
(Linnaeus, 1758)].
Hydroids from Japanese tsunami marine debris
427
Figure 1. (a) Bougainvillia muscus: part of a dormant colony,
with stem, branches, and a single pseudohydrotheca. ROMIZ
B3986. Scale equals 0.25 mm. (b) Stylactaria sp.: parts of a colo-
ny, with two gastrozooids and a dactylozooid. ROMIZ B3987.
Scale equals 0.25 mm. (c) Phialella sp: part of a hydrocaulus,
with one intact and two damaged hydrothecae. ROMIZ B3989.
Scale equals 0.1 mm. (d) Eutima japonica: single hydranth, with
basal disc. ROMIZ B3992. Scale equals 0.25 mm.
Del. DR Calder.
Perigonymus muscus Allman, 1863: 12 [incorrect
subsequent spelling of Perigonimus M. Sars, 1846].
Material.–USA: Washington state, Grays
Harbor, Damon Point, on derelict boat, 28 July
2012, one dormant colony, with coenosarc but
without hydranths and gonophores, coll. J
Schultz and A Pleus (JTMD-BF-12), ROMIZ
B3986.
Remarks.–Identification of this material as
Bougainvillia muscus (Allman, 1863), based on
overall colony morphology, is somewhat
uncertain because of its poor condition. Much of
the examined material comprised dead colonies
growing on and amongst colonies of Obelia
longissima (Pallas, 1766). One live colony,
lacking hydranths but with coenosarcal tissue in
stems and branches, was present. This species,
known in many earlier accounts as Bougainvillia
ramosa (Van Beneden, 1844b), is reported to be
amphi-Pacific in distribution (Yamada 1959;
Hirohito 1988; Mills et al. 2007).
Family Hydractiniidae L. Agassiz, 1862
Stylactaria sp.
(Figure 1b)
Material.–USA: Oregon, Lincoln County,
Gleneden Beach, 05 February 2013, on barnacle
from derelict boat, one colony, with gastrozooids
and dactylozooids, gonozooids lacking, coll. JW
Chapman and JA Miller (JTMD-BF-23, Sample
#12), ROMIZ B3987.
Remarks.–Stylactaria Stechow, 1921 has been
included in the synonymy of Hydractinia Van
Beneden, 1844a in some contemporary works (e.g.
Bouillon et al. 2006), while being maintained as
distinct in others (e.g. Calder 2010; Miglietta et
al. 2010). We follow the latter convention, and
assign the colony examined here to Stylactaria
because zooids arise from a reticulate network of
perisarc-covered stolons rather than from an
encrusting mat of coalesced coenosarc (see Miglietta
and Cunningham 2012). In the absence of gono-
zooids and gonophores, the identity of the species
cannot be confidently established on morphological
characters. The colony was small and in good
condition, and appeared to be quite young.
While the precise origin of the material is
obscure, this is the first record of the genus
Stylactaria from the west coast of the United
States and Canada. It is represented by several
species in Japan (Hirohito 1988; Bouillon et al.
1997), and our hydroid likely originated there.
Order Leptothecata Cornelius, 1992a
Family Phialellidae Russell, 1953
Phialella sp.
(Figure 1c)
Material.–USA: Oregon, Newport, Agate Beach,
05 June 2012, on barnacle amongst fouling from
a floating dock (originating from Misawa,
Honshu, Japan), one stolonal and branching
colony, without gonothecae, coll. JW Chapman
and JA Miller (JTMD-BF-1, High North Dock
sample), ROMIZ B3988.–USA: Oregon,
Newport, Agate Beach, 05 June 2012, on
barnacle amongst fouling from a floating dock
(originating from Misawa, Honshu, Japan),
without gonothecae, coll. JW Chapman and JA
Miller, and others (from JTMD-BF-1, Samples
122–131), ROMIZ B3989.–USA: Oregon,
Newport, Agate Beach, 06 June 2012, on fouling
from a floating dock (originating from Misawa,
D.R. Calder et al.
428
Honshu, Japan), one colony, without gonothecae,
coll. JW Chapman and JA Miller (JTMD-BF-1,
High North Dock sample), ROMIZ B3990.
Remarks.–While our material could not be
identified to species with confidence because of
the lack of gonophores, these hydroids are likely
to have originated in Japan. The floating dock
from Misawa, on which specimens were found,
is thought not to have acquired species in the
eastern North Pacific prior to stranding. That
judgment is based upon identifications of many
other invertebrate and algal species, as discussed
below.
A species closely resembling our material, and
one reported from the Sea of Japan (Naumov 1960),
is Phialella quadrata (Forbes, 1848). Originally
described from Great Britain, it is held to be
almost cosmopolitan in distribution. The specimens
also closely correspond morphologically with
accounts of Opercularella rugosa (Nutting, 1901),
originally described from Harriman Alaska
Expedition collections taken at Juneau, Alaska.
That species has been reported as well from
West Seattle, Washington, and questionably from
Oakland, California (Fraser 1946). Opercularella
rugosa, originally assigned to Campanulina Van
Beneden, 1847 and transferred to Opercularella
Hincks, 1868 by Cairns et al. (2002: 54), has been
regarded as an indigenous west coast species.
Given the similarities between O. rugosa and P.
quadrata, however, studies are needed to determine
whether they are identical. Both are distinguished
from O. lacerata (Johnston, 1847) in having much
stouter hydrothecae, and in having medusa stages
rather than fixed sporosacs in their life cycles.
Another species from the North Pacific region
with somewhat similar characters is Campanulina
chilensis Hartlaub, 1905, reported with question
from Sagami Bay, Japan, by Stechow (1913).
However, our material differs from that of Stechow
in having erect rather than stolonal colonies, and
hydrothecae that are much less cylindrical in
shape.
Family Eirenidae Haeckel, 1879
Eutima japonica Uchida, 1925
(Figures 1d, 2, 3)
Eutima japonica Uchida, 1925: 93, figure 17.
Material.–USA: Washington, Olympic National
Park, near Mosquito Creek, 21 December 2012,
in Mytilus galloprovincialis Lamarck, 1819 from
floating dock (originating from Misawa, Honshu,
Japan), several polyps, without gonophores, coll.
JW Chapman, JA Miller, and others (JTMD-BF-8,
Figure 2. Eutima japonica: live polyps, in Mytilus
galloprovincialis from dock stranded at Mosquito Creek,
Washington, 21 December 2012 (JTMD-BF-8). (a) Group of
hydranths on gill of host mussel. (b) Single hydranth.
Photographs by Leslie Harris.
Figure 3. Eutima japonica: nematocysts, ROMIZ B3992. (a)
Elongate microbasic mastigophore. (b) Oval microbasic
mastigophore. Photomicrographs by DR Calder.
Sample #9B), ROMIZ B3991.–USA: Washington,
Olympic National Park, near Mosquito Creek, 21
December 2012, in Mytilus galloprovincialis
from floating dock (originating from Misawa,
Honshu, Japan), several polyps, without
gonophores, coll. JW Chapman, JA Miller, and
others (JTMD-BF-8, Sample #20), ROMIZ
B3992.
Remarks.–The commensal hydroid Eutima
japonica Uchida, 1925 has been reported from
cooler regions along the Japanese coast from
Hokkaido in the north to Kyushu in the south,
and is likely endemic to Japanese waters (Kubota
1983). The morphologically indistinguishable
hydroid of Eugymnanthea japonica Kubota, 1979
occurs primarily in warmer waters influenced by
the Kuroshio Current (Kubota 1992). According to
Kubota, the two species tend to inhabit different
native bivalve species, although both occur in
the introduced Mytilus galloprovincialis. Our
preliminary identification of material from tsunami
debris as E. japonica, based on the geographic
Hydroids from Japanese tsunami marine debris
429
origin of the floating dock, was confirmed by
molecular analysis (Geller, unpublished data).
We obtained 311 bp of Cytochrome c oxidase
subunit I, which was 100% identical to GenBank
accession AB458489 (Kobayashi A, Goka K,
Kubota S, per Arei Kobayashi, Kyushu University,
Faculty of Sciences, 6-10-1, Hakozaki, Higashi,
Fukuoka 812-8581, Japan, unpublished), identified
as Eutima japonica and collected in Japan.
Sequences for the genetically distinct Eugymnanthea
japonica have also been characterized (Govindarajan
et al. 2005b).
Although the exact relationship with their hosts
is not clear, polyps of Eutima japonica live in the
mantle cavities of bivalve molluscs, attaching to
tissues of the mantle cavity by stolonal structures
or by hydrorhizae penetrating into the host tissues
(Boero and Bouillon 2005).
Commensal eutimid hydroids are previously
unreported from the west coast of North America,
and the species reported here is considered alien
to North American waters. Related species occurring
in the western North Atlantic include Eutima
ostrearum Mattox and Crowell, 1951 (from the
Mangrove Cupped Oyster, Crassostrea rhizophorae)
in Puerto Rico, and Eutima sp. from Atlantic
(Kubota and Larson 1990) and Gulf coasts (Tolley
et al. 2010) of Florida (in both regions in the
Eastern Oyster, Crassostrea virginica).
Family Campanulariidae Johnston, 1837
Obelia griffini Calkins, 1899
(Figures 4a–c)
Obelia griffini Calkins, 1899: 357, pl. 4, figures
18, 18A-C; pl. 6, figure 18D.
Material.–USA: Oregon, Lincoln County,
Gleneden Beach, 05 February 2013, on Lepas sp.
from derelict boat, one colony, with gonothecae,
coll. JW Chapman and JA Miller (JTMD-BF-23),
ROMIZ B3995.–USA: Oregon, Lincoln County,
Gleneden Beach, 05 February 2013, on
styrofoam from stranded boat, one colony, with
gonothecae, coll. JW Chapman and JA Miller
(JTMD-BF-23, un-numbered sample), ROMIZ
B3996.–USA: Oregon, Newport, Agate Beach, 06
June 2012, amongst fouling from a floating dock
(originating from Misawa, Honshu, Japan), one
colony, without gonothecae, coll. JW Chapman
and JA Miller (JTMD-BF-1, High North Dock
sample), ROMIZ B3997.–USA: Oregon,
Newport, Agate Beach, 05 June 2012, amongst
fouling from a floating dock (from Misawa,
Honshu, Japan), one colony, with gonothecae,
coll. JW Chapman and JA Miller (JTMD-BF-1,
Sample B12), ROMIZ B3998.–USA: Oregon,
Newport, Agate Beach, 05 June 2012, on
barnacles and amongst fouling from a floating
dock (originating from Misawa, Honshu, Japan),
without gonothecae, coll. JW Chapman, JA
Miller, and others (JTMD-BF-1, Samples 122–131),
ROMIZ B3999.–USA: Washington, Olympic
National Park, near Mosquito Creek, 21 December
2012, from fouling on floating dock (originating
from Misawa, Honshu, Japan), several colonies,
without gonothecae, coll. JW Chapman, JA Miller,
and others (JTMD-BF-8, Sample #20), ROMIZ
B4000.–USA: Washington, Olympic National Park,
near Mosquito Creek, 21 December 2012, from
fouling on floating dock (from Misawa, Honshu,
Japan), several colonies, with gonothecae, coll.
JW Chapman, JA Miller, and others (JTMD-BF-
8, Sample #34), ROMIZ B4001.
Remarks.–Hydroid colonies examined here
corresponded most closely with accounts of Obelia
griffini Calkins, 1899 (type locality: Puget Sound,
Washington), generally considered conspecific
with O. dichotoma (Linnaeus, 1758). We retained
O. griffini as distinct largely because hydrothecae
in our specimens were round rather than polygonal
in cross-section as in O. dichotoma, and hydrothecal
margins were entire rather than polyhedral.
According to Fraser (1914), O. griffini is also more
profusely branched than O. dichotoma. Moreover,
it seems likely that the supposedly cosmopolitan
O. dichotoma (type locality: SW coast of England)
comprises a species complex, like its congener
O. geniculata (Linnaeus, 1758) (Govindarajan et
al. 2005a).
Similar and regarded as conspecific with
Obelia griffini are O. surcularis Calkins, 1899
and O. gracilis Calkins, 1899, both originally
described from Puget Sound, Washington (type
locality: Scow Bay, Port Townsend Harbor).
Characters used to distinguish the three are
believed by us to have been based merely on
different growth forms. Of the three simultaneous
synonyms O. griffini, O. gracilis, and O. surcularis,
we assign precedence to the name O. griffini
under the Principle of the First Reviser (ICZN
Art. 24.2). In addition, Obelia gracilis Calkins,
1899 is a junior secondary homonym of Lomedea
(sic) gracilis Dana, 1846 from gulfweed in the
Sargasso Sea (34°39´N, 72°01´W). A replacement
name for O. gracilis Calkins is unnecessary as it
is now a junior synonym of O. griffini (ICZN Art
60.2).
Hydroids identified as Obelia griffini or one
of its synonyms have been reported from Puget
D.R. Calder et al.
430
Figure 4. (a) Obelia griffini: part of a colony, with hydrothecae and a gonotheca. ROMIZ B3996. Scale equals 0.25 mm. (b) Obelia
griffini: part of a colony, with four hydrothecae. ROMIZ B3999. Scale equals 0.25 mm. (c) Obelia griffini: part of a colony, with a single
hydrotheca. ROMIZ B3996. Scale equals 0.2 mm. (d) Obelia longissima: part of a colony, with a hydrotheca and a gonotheca. ROMIZ
B4002. Scale equals 0.5 mm. (e) Orthopyxis caliculata: two views of a single bilaterally symmetrical hydrotheca, showing differential
thickening of perisarc. ROMIZ B3993. Scale equals 0.25 mm. (f) Orthopyxis platycarpa: two hydrothecae. ROMIZ B3994. Scale equals 0.2
mm. Del. DR Calder.
Sound northwards to several localities around
Vancouver Island (Fraser 1946). Obelia gracilis
Calkins (not O. gracilis Dana) has also been
reported from China (Hargitt 1927; Ling 1938;
Gao 1956; Wei 1959), and it was characterized
as one of the hydroid species typical of the South
Kurilean region of Russia by Antsulevich (1992).
Obelia griffini was found on three of the four
stranded objects sampled as part of this study.
The history of the species is not well-known
across the North Pacific. Given its propensity to
be a fouling organism, we regard it as cryptogenic
on the coasts of both eastern Asia and western
North America.
Obelia longissima (Pallas, 1766)
(Figure 4d)
Sertularia longissima Pallas, 1766: 119.
Material.–USA: Washington state, Grays Harbor,
Damon Point, on derelict boat, 28 December 2012,
several colonies, with empty gonothecae, coll. J
Schultz and A Pleus (JTMD-BF-12), ROMIZ
B4002.
Remarks.–Obelia longissima (Pallas, 1766) is
amphi-Pacific in distribution, having been reported
from the Bering Sea (Naumov 1960) southwards
to Korea (Park 1990) and the north coast of China
(Gao 1956; Wei 1959) in the west, and from Alaska
to California in the east (Fraser 1937, 1946; Calder
1970). It occurs on both sides of the North
Atlantic Ocean as well, and populations extend
into Arctic waters (Naumov 1960; Calder 1970,
2012; Schuchert 2001).
Although colonies of Obelia longissima are
known to survive for at least several months
(Cornelius 1990), the life span of a given genet
is potentially much longer. Hydroids that clone
by asexual reproduction (as is the case with
O. longissima) may survive for very long periods,
according to Gili and Hughes (1995: 374, 375).
Moreover, resting stages (menonts) exist in hydroids
Hydroids from Japanese tsunami marine debris
431
that prolong survival (Calder 1990). Given the
large size (up to 24 cm high), weathered condition,
and empty gonothecae of colonies examined
here, we conclude that they had been on the derelict
boat for at least several months and that the
colonies or their genetically identical predecessors
originated in Japan.
Orthopyxis caliculata (Hincks, 1853)
(Figure 4e)
Campanularia caliculata Hincks, 1853: 178, pl.
5, figure B.
Material.–USA: Washington, Olympic National
Park, near Mosquito Creek, 21 December 2012,
one small colony, from a floating dock (originating
from Misawa, Honshu, Japan), without gonophores,
coll. JW Chapman, JA Miller, and others (JTMD-
BF-8, Sample #M3), ROMIZ B3993.
Remarks.–Material examined here corresponds
in morphology to hydroids sometimes known as
Orthopyxis caliculata (Hincks, 1853), originally
described from the British Isles. The species is
frequently held to be identical with Orthopyxis
integra Macgillivray, 1842 (e.g., Levinsen 1893;
Broch 1910, 1918; Kramp 1911; Naumov 1960;
Cornelius 1982, 1995; Vervoort and Watson 2003;
Schuchert 2013b). Broch (1918: 160) reported
finding forms corresponding to the two putative
species, together with transitional ones, on the
same stolons. Nevertheless, molecular studies are
warranted to establish the relationship between
O. integra and O. caliculata because the two
appear to differ in characters of both trophosome
and gonosome. Notably, hydrothecae are bilaterally
symmetrical in O. caliculata rather than being
radially symmetrical as in O. integra (Table 1),
and gonothecae are sac-shaped without annulated
walls instead of being nearly cylindrical with
spirally grooved walls (Naumov 1960). Despite the
absence of gonothecae in our sample, differences
in hydrothecal morphology sufficiently differentiate
O. caliculata from O. integra (Table 1). As for
O. integra, widely reported and generally believed
to be nearly cosmopolitan (Cornelius 1995), its
identity is not at all firmly established. The
original account of the species was brief and no
illustration was provided. Type material, from the
mouth of the River Don at Aberdeen, Scotland,
could not be located in a study of eastern North
Atlantic campanulariids by Cornelius (1982). A
neotype is needed to objectively define the
species.
Hirohito (1995) provided taxonomic information
on several species of Orthopyxis L. Agassiz,
1862 from Japan, although all of them were
referred by him to genus Campanularia Lamarck,
1816. Campanularia caliculata was treated by
him as a valid species, and the account of his
material from Japan corresponds with hydroids
examined here. Hirohito’s specimens were similar
to ones that he had examined from the Shetland
Islands, UK, in collections at the British Museum
(Natural History) (now The Natural History
Museum) in London. In the western North Pacific,
O. caliculata has also been reported from Korea
(Park 1990) and Sakhalin, Russia (Hirohito 1995).
Hydroids corresponding to accounts of
Orthopyxis caliculata have been reported earlier
from the west coast of North America by Nutting
(1901, 1915). Notably, however, those identified
by Calkins (1899) as O. caliculata from Puget
Sound, Washington, differ somewhat in morpho-
logy, and Stechow (1919) provided a new name,
O. pacifica, for them. Fraser (1914, 1937, 1946),
who seems to have followed Calkins’ concept of
the species, assigned it to Eucopella von
Lendenfeld, 1883. The identity of Campanularia
compressa Clark, 1877 from Alaska, resembling
O. caliculata but included in the synonymy of O.
integra by Schuchert (2013b), needs to be clarified.
Orthopyxis platycarpa Bale, 1914
(Figure 4f)
Orthopyxis platycarpa Bale, 1914: 79, pl. 11,
figure 3, pl. 12, figure 3.
Material.–USA: Oregon, Lincoln County,
Gleneden Beach, 05 February 2013, from derelict
boat, several pedicels with hydrothecae, without
gonothecae, coll. JW Chapman and JA Miller
(JTMD-BF-23), ROMIZ B3994.
Remarks.–These hydroids correspond with
accounts of Orthopyxis platycarpa Bale, 1914
from Japan (Stechow and Uchida 1931; Hirohito
1995), China (Ling 1938), and Russia (Naumov
1960; Antsulevich 1987). Specimens from Korea
identified as this species by Rho (1967) more
closely resemble O. caliculata in our opinion.
Orthopyxis platycarpa has been regarded in some
works (e.g. Schuchert 2013b) as conspecific with
O. integra (Macgillivray, 1842), although
gonothecae of the latter usually have a distinctive
spiral carina around the exterior wall instead of
being smooth. Other apparent differences distin-
guishing O. platycarpa from O. integra include the
frequent occurrence of a convex submarginal band
of thickened perisarc on the hydrothecae, and
gonothecae that are distinctly flattened (Bale 1914).
Moreover, acrocysts are extruded from female
D.R. Calder et al.
432
Table 1. Comparisons of some trophosomal characters in specimens of Orthopyxis caliculata, O. platycarpa, and O. integra from
collections at the Royal Ontario Museum, together information on O. platycarpa from Naumov (1960, as Campanularia platycarpa).
Measurements (μm): O. caliculata
(ROMIZ B3993)
O. platycarpa
(ROMIZ B3994)
O. platycarpa
(Naumov 1960)
O. integra
(ROMIZ B4020)
Hydrotheca height (A) 1160–1190 680 320–640 1170–1800
Hydrotheca maximum width (B) 800–830 550 not stated 1020–1210
Hydrotheca mouth maximum diameter (C) 800–860 570 270–400 940–1210
Hydrothecal submarginal perisarc thickening (D) 50–80 10 not stated 90–121
Pedicel height (E) 1193–2260 1130 800–4000 5070–9160
Hydrothecal symmetry bil ate ral rad ial radial rad ial
Hydrothecal submarginal band no yes yes no
Figure 5. (a) Halecium tenellum: part of a colony, with hydrothecae. ROMIZ B4004. Scale equals 0.25 mm. (b) Hydrodendron gracile:
part of a colony, with four hydrothecae and three nematophores. ROMIZ B4005. Scale equals 0.2 mm. (c) Amphisbetia furcata: part of a
hydrocaulus, with two pairs of hydrothecae. ROMIZ B4008. Scale equals 0.1 mm. (d) Sertularella sp.: part of a hydrocaulus, with three
hydrothecae and a gonotheca. ROMIZ B4009. Scale equals 0.25 mm. (e) Plumularia sp.: part of a hydrocaulus, and basal segments of a
hydrocladium. ROMIZ B4006. Scale equals 0.25 mm. (f) Plumularia sp.: part of a hydrocladium, with nematothecae and two hydrothecae.
ROMIZ B4006. Scale equals 0.25 mm. (g) Plumularia setacea: part of a hydrocaulus, and basal segments of two hydrocladia. ROMIZ
B4007. Scale equals 0.25 mm. (h) Plumularia setacea: part of a hydrocladium, with nematothecae and two hydrothecae. ROMIZ B4007.
Scale equals 0.25 mm. Del. DR Calder.
Hydroids from Japanese tsunami marine debris
433
gonophores of O. platycarpa rather than
eumedusoids, as in O. integra (Hirohito (1995).
Considerable differences in hydrothecal dimensions
were apparent in specimens of O. platycarpa, O.
integra, and O caliculata examined here (Table 1).
This species has not been reported before from
the west coast of North America.
Family Haleciidae Hincks, 1868
Halecium tenellum Hincks, 1861
(Figure 5a)
Halecium tenellum Hincks, 1861: 252, pl. 6,
figures 1–4.
Material.–USA: Oregon, Newport, Agate Beach,
05 June 2012, on barnacle fragment amongst fouling
from a floating dock (originating from Misawa,
Honshu, Japan), one colony, without gonothecae,
coll. JW Chapman and JA Miller (JTMD-BF-1,
High North Dock sample), ROMIZ B4003.–
USA: Washington, Olympic National Park, near
Mosquito Creek, 21 December 2012, on barnacle
from fouling on floating dock (originating from
Misawa, Honshu, Japan), without gonothecae, coll.
JW Chapman, JA Miller, and others (JTMD-BF-
8, Sample #9B), ROMIZ B4004.
Remarks.–Identification of examined material
is somewhat uncertain because of the lack of
gonophores, although the trophosomes corresponded
most closely with accounts of Halecium tenellum
Hincks, 1861. Our material showed occasional
annulation in the stems (Fraser 1937), and weak
constrictions were generally present at the base
of the branches as reported by Hirohito (1995).
Halecium tenellum is known from both northeastern
and northwestern Pacific regions, having been
reported in the latter area from Japan (Jäderholm
1919; Yamada 1959; Hirohito, 1995), Russia
(Naumov 1960; Antsulevich 1987), Korea (Park
1991), and with some question from China (Hargitt
1927). Records from the northeastern Pacific are
summarized in Fraser (1937). Halecium tenellum
has been very widely reported (from Atlantic,
Pacific, Indian, and Arctic oceans), and genetic
studies may reveal the existence of a species
complex.
Hydrodendron gracile (Fraser, 1914)
(Figure 5b)
Ophiodes gracilis Fraser, 1914: 171, pl. 22,
figures 82A–D.
Material.–USA: Oregon, Lincoln County,
Gleneden Beach, 05 February 2013, from derelict
boat, one colony, without gonothecae, coll. JW
Chapman and JA Miller (JTMD-BF-23), ROMIZ
B4005.
Remarks.–Fraser (1914) described this hydroid,
as Ophiodes gracilis, from Vancouver Island and
the Queen Charlotte Islands (=Haida Gwaii), British
Columbia. Plumularia linkoi Naumov, 1960,
originally described from the Black Sea, has been
regarded as a probable synonym (Schuchert 2013b).
In the North Pacific Ocean, Hydrodendron gracile
has been reported from the Sea of Japan and the
Kurile Islands (Naumov 1960, as Plumularia
magellanica moneroni Naumov, 1960; Antsulevich
1987, as Hydrodendron gracilis) as well as from
British Columbia (Fraser 1937, as Ophiodissa
gracilis). The colony examined here, in quite good
condition and appearing relatively young, closely
resembles accounts of the species by Naumov
(1960) and Antsulevich (1987). A combination of
characters (stolonal colony form; monosiphonic
hydrocaulus; tiny, curved nematothecae) distinguish
the species from others of the genus known from
the northern North Pacific (Fraser 1937; Hirohito
1995). Hydrodendron gracile was originally
described from sterile material, and it remains an
inadequately characterized species.
Family Sertulariidae Lamouroux, 1812
Amphisbetia furcata (Trask, 1857)
(Figure 5c)
Sertularia furcata Trask, 1857: 101, pl. 5,
figures 2a–e.
Material.–USA: Oregon, Newport, Agate Beach,
05 June 2012, wash from fouling from a floating
dock (originating from Misawa, Honshu, Japan),
fragment of a single stem, without gonothecae,
coll. JW Chapman and JA Miller (JTMD-BF-1,
Sample B12), ROMIZ B4008.
Remarks.–Amphisbetia furcata (Trask, 1857),
originally described from San Francisco Bay,
California, and A. pacifica Stechow, 1931, type
locality Mutsu Bay, Japan, differ only in minor
characters. According to Yamada (1959: 69),
A. pacifica is distinguished in having “...2 distinct
spiral constrictions at the base of the stem and in
gonothecae which are not globular but elongated
oval and having unremarkable shoulders.” We
consider such differences to be taxonomically
insignificant and agree with Antsulevich (1987)
that the two are coterminous. Notably, gonothecae
of A. furcata are known to vary in shape (see
Clark 1876, pl. 39, fig. 3). Moreover, diagrams
of gonothecae of A. furcata from California by
Torrey (1902) and of A. pacifica from Japan by
Hirohito (1995) are much alike. The bases in
D.R. Calder et al.
434
both putative species have hinge joints, frequent
in sertulariid species occurring on algal substrates
that are swept by waves and currents.
Amphisbetia furcata or its synonym A. pacifica
have been reported from shores along both the
northeastern and northwestern Pacific (e.g. Fraser
1937, 1946; Gao 1956; Yamada 1959; Wei 1959;
Rho 1967; Antsulevich 1983, 1987; Park 1990;
Hirohito 1995). Coenosarc was still apparent within
the perisarcal skeleton of our fragmentary hydroid,
but it was old, almost completely covered in
diatoms, and in quite poor condition. We therefore
conclude that it originated in Japan.
Sertularella sp.
(Figure 5d)
Material.–USA: Oregon, Newport, Agate Beach,
05 June 2012, from fouling on a floating dock
(originating from Misawa, Honshu, Japan), several
colony fragments, with gonothecae, coll. JW
Chapman and JA Miller (JTMD-BF-1, Sample
B12), ROMIZ B4009.–USA: Oregon, Newport,
Agate Beach, 05 June 2012, from fouling on a
floating dock (originating from Misawa, Honshu,
Japan), one fragment, without gonothecae, coll.
JW Chapman and JA Miller (JTMD-BF-1, Sample
B19), ROMIZ B4010.
Remarks.–Comparison of our samples to
documented Japanese and northwestern Pacific
species of Sertularella, such as S. levigata
Stechow, 1931, S. miurensis Stechow, 1921
(including S. miurensis var. pungens Stechow,
1931), S. lagenoides Stechow, 1919, S. mutsuensis
Stechow, 1931, and S. sagamina Stechow, 1921,
as well as northeastern Pacific and North Atlantic
congeners, shows that material above appears
morphologically distinct. Several species assigned
to Sertularella Gray, 1848 in the North Pacific
region, including the species listed above, are
inadequately described and poorly differentiated,
and a taxonomic reassessment of them is needed.
As a result, we have yet to refer our material
with confidence to any of these putative species.
Hydroids in our samples (ROMIZ B4009,
ROMIZ B4010) do not readily correspond with
species of Sertularella from the west coast of
North America that we know. Pending further
taxonomic analysis and identification, we surmise
that this species is likely alien to North America.
Given the uncertain identity of this hydroid, a
preliminary description of it is given below.
Observed thickening of the perisarc throughout
the exoskeleton and annulations on internodes
below the hydranths are both consistent with
morphological adaptations to potentially damaging
moving-water conditions. Annulations allow the
hydrocaulus to bend without damage, and enable
orientation that enhances food capture in strong
currents (Hughes 1992).
Description.–Colony erect, unbranched, with
a monosiphonic, somewhat geniculate hydrocaulus
comprised of a succession of short, pedicel-like
internodes having 2–4 annulations basally; each
such internode slender basally, thickest distally
at insertion of hydrotheca. Perisarc thickened
throughout. Hydrothecae flask-shaped, arranged
alternately to somewhat spirally; walls appearing
mostly smooth in lateral view but with 2–3 slight
annulations apparent in polar view, constricted
below margin, with up to half of adcauline wall
adnate to internode; margin slightly flaring, with
four distinct, equally-developed cusps; operculum
of four triangular valves; hydrothecal perisarc
variably thickened internally below aperture, in
some cases appearing bulbous and resembling
intrathecal cusps; true intrathecal cusps absent or
not apparent in polar view. Gonothecae sac-
shaped with a narrow neck, each arising by a
short, tapered pedicel from internode below base
of hydrotheca, walls appearing almost smooth
laterally but with faint rings visible in polar
view; aperture surrounded by 4–5 cusps; internal
projections absent.
Family Plumulariidae McCrady, 1859
Plumularia sp.
(Figures 5e, f)
Material.USA: Oregon, Newport, Agate Beach,
05 June 2012, on fouling from a floating dock
(from Misawa, Honshu, Japan), one colony, with
remnants of coenosarc in stems, without gonothecae,
coll. JW Chapman and JA Miller (JTMD-BF-1,
Sample B12), ROMIZ B4006.
Remarks.–This hydroid was represented by a
single colony fragment that was sterile and in
imperfect condition. In many respects it corresponds
in morphology with accounts of Plumularia
lagenifera Allman, 1885, a species distinguished
from the related P. setacea (Linnaeus, 1758) in
having hydrothecae with a convex abcauline wall
(Schuchert 2013a) (compare Figures 17, 18).
However, P. lagenifera shares that character with
P. caliculata Bale, 1888 from Australia and Japan.
The two species are most easily distinguished by
their female gonothecae, which were absent in
our material. Those of P. caliculata are globular
rather than flask-shaped with a tubular neck, and
a marsupium is extruded. Our specimen was
Hydroids from Japanese tsunami marine debris
435
compared to a sample of P. lagenifera from the
Vancouver Island area in collections at the Royal
Ontario Museum (Canada, British Columbia, Stuart
Channel, Round Island, depth 37 m, 15 June 1923,
ROMIZ B4011). No morphological differences
were apparent between them. Lengths of some
trophosomal characters were closer to those of P.
lagenifera than to P. caliculata (Table 2). We
conclude that the specimen can be confidently
identified only to generic rank in the absence of
gonophores, but its substrate and collection date
point to P. caliculata (see Discussion). Although
the colony fragment was in rather poor
condition, strands of coenosarc were still visible
within the perisarcal skeleton.
Plumularia lagenifera, originally described from
Vancouver Island, British Columbia (Allman 1885),
is a familiar species along the west coast of the
United States and Canada (Fraser 1937; Mills et
al. 2007). Although it has been reported in the
western North Pacific (Stechow 1913; Hargitt 1927),
those records are now believed to have been
based on hydroids of P. caliculata (Stechow
1923: 17; Yamada 1959: 79; Hirohito 1995: 271).
Rho and Park (1980) reported P. lagenifera from
Korea, but their hydroid seems likely to have
been P. caliculata as well.
Plumularia setacea (Linnaeus, 1758)
(Figures 5g, h)
Sertularia setacea Linnaeus, 1758: 813.
Material.–USA: Oregon, Lincoln County,
Gleneden Beach, 05 February 2013, from derelict
boat, several plumes, without gonothecae, coll.
JW Chapman and JA Miller (JTMD-BF-23),
ROMIZ B4007.
Remarks.–We assigned our material to
Plumularia setacea (Linnaeus, 1758) in spite of
the total absence of nematothecae on ahydrothecate
internodes of the hydrocladia. Apart from axillary
ones at apophysal bases, nematothecae were also
absent on internodes of the hydrocaulus.
Trophosomes thus resembled hydroids identified
as Plumularia sp. by Hirohito (1995) from Sagami
Bay, Japan, although his specimens were illustrated
without internal perisarcal ridges. The ahydro-
thecate internodes of our specimens were
consistently very short and they were often
replicated, with as many as six occurring in
sequence. In other respects, hydroids examined
here generally corresponded to accounts of
P. setacea, including that of Schuchert (2013a).
While we provisionally conclude that the observed
differences in morphology are not taxonomically
significant, we acknowledge that a high degree
of genetic diversity exists within P. setacea, and
cryptic species may exist (Schuchert 2014).
Plumularia setacea is taken to be an amphi-
Pacific species (e.g. Jäderholm 1896; Fraser 1937;
Gao 1956; Wei 1959; Naumov 1960; Rho 1967;
Hirohito 1995; Schuchert 2013a). Colonies appear
to have been present on the derelict boat for
several weeks or months; parts of some plumes
comprised only empty skeletal perisarc, and bases
of hydrocauli were overgrown with bryozoans.
Discussion
Of more than 100 species found on the dock
from Misawa, Japan (JTMD-BF-1), that landed
in Oregon during June 2012, and more than 30
species on the Japanese vessel that washed ashore at
Gleneden, Oregon, during February 2013 (JTMD-
BF-23) (JT Carlton, JW Chapman, J Geller, JA
Miller, and G. Ruiz, unpublished data), none
appear to have been acquired after the vessel
entered the eastern Pacific Ocean. It is thus difficult
to imagine that only species of eastern Pacific
hydrozoans settled on these objects but no other
eastern Pacific marine invertebrates. In contrast,
the second dock from Misawa that washed ashore
during December 2012 in the state of Washington
(JTMD-BF-8) included eastern Pacific species of
snails, isopods, and ascidians, among other
possible taxa, acquired as the dock floated along
the North American coast before or after landing.
None of the hydroids discussed here are clearly
introduced (Table 3) on the Pacific coast of North
America, but several species may be cryptogenic
- that is, we do not know whether they are native
or exotic. These include Bougainvillia muscus,
Obelia griffini, and Obelia longissima. Authors
have previously considered the first and last as
possible introductions to the eastern Pacific Ocean,
based upon their history, patchy distribution,
and/or predominance in ports and harbors (Mills
et al. 2007). In all, six species found on Japanese
tsunami marine debris are not yet known from
the eastern Pacific (Table 3): Stylactaria sp., Eutima
japonica, Orthopyxis platycarpa, Sertularella
sp., S. mutsuensis, and Plumularia sp. All of
these species should be included as target taxa in
biodiversity surveys of fouling communities on
the Pacific coast of North America. Especially to
be sought for there would be evidence of Eutima
japonica in species of Mytilus, or indeed, in
other bivalves (see Kubota 1983; Baba et al.
2007).
D.R. Calder et al.
436
Table 2. Size comparisons of some characters in Plumularia lagenifera, Plumularia caliculata, and Plumularia sp.
Length (μm) Plumularia lagenifera
(in Schuchert 2013)
Plumularia sp. (ROMIZ
B4006)
Plumularia caliculata (in
Vervoort and Watson
2003)
Stem internode 405–589 455–485 310–390
Branch, thecate internode 395–514 325–410 265–335
Branch, athecate internode 153–226 140–195 100–115
Hydrotheca, abcauline wall 90–115 105–125 45–73
Table 3. The North Pacific distributions and biogeographic origins of hydroids associated with Japanese Tsunami Marine Debris (JTMD)
coming ashore on the Pacific coast of North America. Data on Sertularella mutsuensis from Choong and Calder (2013).
Species
Previously known
from the North
Western Pacific
(NWP)
Previously
known from the
North Eastern
Pacific (NEP)
Status in NEP:
N native
I introduced
C cryptogenic
Comments
Bougainvillia
muscus (?) + +
I? (Mills et al. 2007: 151,
"probably introduced")
Identification uncertain due to poor
condition of material. Amphi-Pacific
Stylactaria sp. ? - Not known from NEP Genus represented in NWP
Phialella sp. ? ?
Dock not regarded as having acquired
species from NEP (see text). Amphi-Pacific
(?)
Eutima japonica + - Not known from NEP
Obelia griffini + (see Comments) + C (so designated here)
While known from China and Russia, this
appears to be the first record from Japan,
based upon JTMD-BF-1 and BF-23
samples (not JTMD-BF-8, which is
regarded as having acquired Eastern Pacific
taxa; see text discussion). Amphi-Pacific
Obelia longissima + +
C? (so designated here; Mills et
al. 2007: 164; "probable ship
fouling introductions")
Amphi-Pacific
Orthopyxis
caliculata + + N Amphi-Pacific
Orthopyxis
platycarpa + - Not known from NEP
Halecium tenellum + + N (see Comments)
Reported to have a broad temperate-tropical
range in the Atlantic, Pacific, Indian, and
Arctic oceans, and may be a species
complex. Amphi-Pacific
Hydrodendron
gracile + + N
First record for Japan; vessel not regarded
as having acquired species from NEP (see
text). Amphi-Pacific
Amphisbetia
furcata + + N
Sertularella
mutsuensis + - Not known from NEP Reported earlier by Choong and Calder
(2013)
Sertularella sp. ? ? Not known from NEP
See text discussion; JTMD-BF-1 is not
regarded as having acquired species from
NEP (see text)
Plumularia sp. ? - -
Dock not regarded as having acquired
species from NEP (see text); possibly new
to NEP
Plumularia setacea + + N Amphi-Pacific
Hydroids from Japanese tsunami marine debris
437
Worldwide distribution of many hydroid genera
and species gives the impression of near-
cosmopolitanism; therefore, continuing refinement
of species-level taxonomy in making comparisons
between different areas of the world is needed
(Cornelius 1992b). Our examination of hydroids
on tsunami debris, including species of Orthopyxis,
Obelia, Sertularella, and Plumularia underscores
this imperative and provides additional data on
hydroids that form a potential “species club” of
rafters. Although rafting hydroids, especially
leptothecates, tend to be substrate generalists
(Cornelius 1992b), unusually large anthropogenic
floating debris such as docks and boats may
effectively disperse even commensal species such
as Eutima japonica by functioning as substrata
for their hosts. Our results confirm that tsunami
debris can dramatically influence connectivity of
marine communities.
Acknowledgements
Gratitude is extended to A Pleus and J Schultz, Washington
Department of Fish and Wildlife, for providing samples from the
derelict boat that stranded at Grays Harbor, Washington. We are
indebted to T Murphy for assisting with field collections and
laboratory processing of samples, to D Carlton for help in sorting
samples, and to X Song of Qingdao, China, for providing PDF
copies of several relevant publications on hydroids of China. The
photographs of Eutima japonica in Figure 2 were taken by L
Harris. Thanks are due to M Zubowski, Royal Ontario Museum,
for providing collections management assistance, and to A
Antsulevich and two anonymous referees for constructive reviews
of the manuscript. JT Carlton, JW Chapman, and JA Miller
gratefully acknowledge the support of the Oregon Sea Grant
Program (Grant #R/NIS-23-PD), and Carlton, Chapman, Miller,
and Jonathan Geller the support of the National Science
Foundation (Grants #1266417 (Carlton), 1266397 (Miller/
Chapman) and 1266234 (Geller)).
References
Agassiz L (1862) Contributions to the natural history of the
United States of America. Vol. IV. Little, Brown and
Company, Boston, 380 pp
Allman GJ (1863) Notes on the Hydroida. I.–On the structure of
Corymorpha nutans. II. Diagnoses of new species of
Tubularidae obtained, during the autumn of 1862, on the
coasts of Shetland and Devonshire. Annals and Magazine of
Natural History, series 3, 11: 1–12
Allman GJ (1885) Description of Australian, Cape, and other
Hydroida, mostly new, from the collection of Miss H. Gatty.
Journal of the Linnean Society, Zoology 19: 132–161
Antsulevich AE (1983) Novye dlya fauny SSSR gidroidy iz
pribrezhnykh vod Yaponskogo morya. Hydroids from the Sea
of Japan coastal waters new for the USSR fauna.
Zoologicheskiï Zhurnal 62: 1141–1147
Antsulevich AE (1987) Gidroidy shel'fa Kuril'skykh ostrovov.
Hydroids from the shelf waters of Kurile Islands.
Zoologicheskiï Institut, Akademiya Nauk SSSR, pp 1–165
Antsulevich AE (1992) Observations on the hydroid fauna of the
Kurile Islands. Scientia Marina 56 (2–3): 213–216
Baba K, Miyazono A, Matsuyama K, Kohno S, Kubota S (2007)
Occurrence and detrimental effects of the bivalve-inhabiting
hydroid Eutima japonica on juveniles of the Japanese scallop
Mizuhopecten yessoensis in Funka Bay, Japan: relationship to
juvenile mass mortality in 2003. Marine Biology 151: 1977–
1987, http://dx.doi.org/10.1007/s00227-007-0636-x
Bale WM (1888) On some new and rare Hydroida in the
Australian Museum collection. Proceedings of the Linnean
Society of New South Wales, series 2, 3: 745–799
Bale WM (1914) Further notes on Australian hydroids.—III.
Proceedings of the Royal Society of Victoria, new series, 27:
72–93
Boero F, Bouillon J (2005) Cnidaria and Ctenophora (cnidarians
and comb jellies). In: Rohde K (ed), Marine parasitology.
Melbourne and Wallingford, Oxon, U.K., pp 177–182
Bouillon J, Gravili C, Pagès F, Gili J-M, Boero F (2006) An
introduction to Hydrozoa. Mémoires du Muséum National
d’Histoire Naturelle 194, 591 pp
Bouillon J, Medel D, Peña Cantero A (1997) The taxonomic
status of the genus Stylactaria Stechow, 1921
(Hydroidomedusae, Anthomedusae, Hydractiniidae), with the
description of a new species. Scientia Marina 61: 471–486
Broch H (1910) Die Hydroiden der Arktischen Meere. Fauna
Arctica 5: 129–247
Broch H (1918) Hydroida (Part II.). The Danish Ingolf Expedition
5(7), 205 pp
Bryan SE, Cook AG, Evans JP, Hebden K, Hurrey L, Colls P, Jell
JS, Weatherley D, Firn J (2012) Rapid, long-distance
dispersal by pumice rafting. PLoS ONE 7(7): e40583,
http://dx.doi.org/10.1371/journal.pone.0040 583
Cairns SD, Calder DR, Brinckmann-Voss A, Castro CB, Fautin
DG, Pugh PR, Mills CE, Jaap WC, Arai MN, Haddock SHD,
Opresko DM (2002) Common and scientific names of
aquatic invertebrates from the United States and Canada:
Cnidaria and Ctenophora. Second Edition. American
Fisheries Society Special Publication, 28, 115 pp
Calder DR (1970) Thecate hydroids from the shelf waters of
northern Canada. Journal of the Fisheries Research Board of
Canada 27: 1501–1547, http://dx.doi.org/10.1139/f70-175
Calder DR (1990) Seasonal cycles of activity and inactivity in
some hydroids from Virginia and South Carolina, U.S.A.
Canadian Journal of Zoology 68: 442–450, http://dx.doi.org/
10.1139/z90-065
Calder DR (1993) Local distribution and biogeography of the
hydroids (Cnidaria) of Bermuda. Caribbean Journal of
Zoology 29: 61–74
Calder DR (2010) Some anthoathecate hydroids and limnopolyps
(Cnidaria, Hydrozoa) from the Hawaiian archipelago.
Zootaxa 2590: 1–91
Calder DR (2012) On a collection of hydroids (Cnidaria,
Hydrozoa, Hydroidolina) from the west coast of Sweden,
with a checklist of species from the region. Zootaxa 3171: 1–
77
Calder DR, Burrell Jr VG (1969) Brackish water hydromedusa
Maeotias inexpectata in North America. Nature 222: 694–
695, http://dx.doi.org/10.1038/222694a0
Calkins GN (1899) Some hydroids from Puget Sound.
Proceedings of the Boston Society of Natural History 28:
333–367
Carpenter EJ, Smith Jr KL (1972) Plastics on the Sargasso Sea
surface. Science 175: 1240–1241, http://dx.doi.org/10.1126/
science.175.4027.1240
Choong HHC, Calder DR (2013) Sertularella mutsuensis
Stechow, 1931 (Cnidaria: Hydrozoa: Sertulariidae) from
Japanese tsunami debris: systematics and evidence for
transoceanic dispersal. BioInvasions Records 2: 33–38,
http://dx.doi.org/10.3391/bir.2013.2.1.05
Clark SF (1876) The hydroids of the Pacific coast of the United
States, south of Vancouver Island. With a report upon those
D.R. Calder et al.
438
in the museum of Yale College. Transactions of the
Connecticut Academy of Arts and Sciences 3: 249–264
Clark SF (1877) Report on the hydroids collected on the coast of
Alaska and the Aleutian Islands, by W.H. Dall, U.S. Coast
Survey, and party, from 1871 to 1874 inclusive. Proceedings
of the Academy of Natural Sciences of Philadelphia 1876, 28:
209–238
Cornelius PFS (1981) Life cycle, dispersal and distribution among
the Hydroida. Porcupine Newsletter 2: 47–50
Cornelius PFS (1982) Hydroids and medusae of the family
Campanulariidae recorded from the eastern North Atlantic,
with a world synopsis of genera. Bulletin of the British
Museum (Natural History), Zoology 42: 37–148
Cornelius PFS (1990) European Obelia (Cnidaria, Hydroida):
systematics and identification. Journal of Natural History 24:
535–578, http://dx.doi.org/10.1080/00222939000770381
Cornelius PFS (1992a) Medusa loss in leptolid Hydrozoa
(Cnidaria), hydroid rafting, and abbreviated life-cycles
among their remote-island faunae: an interim review. Scientia
Marina 56: 245–261
Cornelius PFS (1992b) The Azores hydroid fauna and its origin,
with discussion of rafting and medusa suppression.
Arquipélago. Life and Earth Sciences 10: 75–99
Cornelius PFS (1995) North-west European thecate hydroids and
their medusae. Part 2. Sertulariidae to Campanulariidae.
Synopses of the British Fauna, n.s., 50, 386 pp
Dana JD (1846) United States Exploring Expedition. During the
years 1838, 1839, 1840, 1841, 1842. Under the command of
Charles Wilkes, U.S.N. Volume VII. Zoophytes. Lea and
Blanchard, Philadelphia, 740 pp
Dumont HJ (1994) The distribution and ecology of the fresh- and
brackish-water medusae of the world. Hydrobiologia 272: 1–
12, http://dx.doi.org/10.1007/BF00006508
Edwards C (1976) A study in erratic distribution: the occurrence
of the medusa Gonionemus in relation to the distribution of
oysters. Advances in Marine Biology 14: 251–284,
http://dx.doi.org/10.1016/S0065-2881 (08)60448-4
Forbes E (1848) A monograph of the British naked-eyed
medusae: with figures of all the species. Ray Society,
London, 104 pp
Fraser CM (1914) Some hydroids of the Vancouver Island region.
Transactions of the Royal Society of Canada, section 4, series
3, 8: 99–216
Fraser CM (1937) Hydroids of the Pacific coast of Canada and the
United States. University of Toronto Press, Toronto, 207 pp
Fraser CM (1946) Distribution and relationship in American
hydroids. University of Toronto Press, Toronto, 464 pp
Gao Z (1956) On the hydroids along Shantung coast. Journal of
Shandong University, series 2, 4: 70–103 (Chinese, with
English summary)
Gili J-M and Hughes RG (1995) The ecology of marine benthic
hydroids. Annual Review of Oceanography and Marine
Biology 33: 351–426
Govindarajan AF, Halanych KM, Cunningham CW (2005a)
Mitochondrial evolution and phylogeography in the
hydrozoan Obelia geniculata (Cnidaria). Marine Biology
146: 213–222, http://dx.doi.org/10.1007/s00227-004-14 34-3
Govindarajan AF, Piraino S, Gravili C, Kubota S (2005b) Species
identification of bivalve-inhabiting marine hydrozoans of the
genus Eugymnanthea. Invertebrate Biology 124: 1–10,
http://dx.doi.org/10.1111/j.1744-7 410.2005.1241-01.x
Gregory MR (2009) Environmental implications of plastic debris
in marine settings—entanglement, ingestion, smothering,
hangers-on, hitch-hiking and alien invasions. Philosophical
Transactions of the Royal Society B, 364: 2013–2025,
http://dx.doi.org/10.1098/rstb.2008.0265
Haeckel E (1879) Das System der Medusen. Erster Theil einer
Monographie der Medusen. Denkschriften der Medicinisch-
Naturwissenschaftlichen Gesellschaft zu Jena, 1, 360 pp
Hargitt CW (1927) Some hydroids of south China. Bulletin of the
Museum of Comparative Zoölogy at Harvard College 67:
491–520
Hartlaub C (1905) Die Hydroiden der magalhaensischen Region
und chilenischen Küste. Zoologische Jahrbücher,
Supplement-Band 6, Fauna Chilensis 3: 497–714
Hincks T (1853) Further notes on British zoophytes, with
descriptions of new species. Annals and Magazine of
Natural History, series 2, 11: 178–185
Hincks T (1861) A catalogue of the zoophytes of south Devon
and south Cornwall. Annals and Magazine of Natural
History, series 3, 8: 251–262
Hincks T (1868) A history of the British hydroid zoophytes. John
van Voorst, London, 338 pp, http://dx.doi.org/10.5962/bhl.title.
1322
Hirohito, The Showa Emperor (1988) The hydroids of Sagami
Bay. Part 1. Athecata. Biological Laboratory, Imperial
Household, Tokyo, Japan, 179 pp
Hirohito, The Showa Emperor (1995) The hydroids of Sagami
Bay. Part II. Thecata. Biological Laboratory, Imperial
Household, Tokyo, Japan, 355 pp
Hughes RG (1992) Morphological adaptations of the perisarc of
the intertidal hydroid Dynamena pumila to reduce damage
and enhance feeding efficiency. Scientia Marina 56(2–3):
269–277
Jäderholm Ε (1896) Ueber aussereuropäische Hydroiden des
zoologischen Museums der Universität Upsala. Bihang till
Kongliga Svenska Vetenskaps-Akademiens Handlingar, 21,
Afd. 4, 6: 1–20
Jäderholm E (1919) Zur Kenntnis der Hydroidenfauna Japans.
Arkiv för Zoologi 12: 1–34
Johnston G (1837) A catalogue of the zoophytes of Berwickshire.
History of the Berwickshire Naturalists’ Club 1: 107–108
Johnston G (1847) A history of the British zoophytes. Second
edition. John Van Voorst, London, 488 pp
Jokiel PL (1989) Rafting of reef corals and other organisms at
Kwajalein Atoll. Marine Biology 101: 483–493,
http://dx.doi.org/10.1007/BF00541650
Kramp PL (1911) Report on the hydroids collected by the
Danmark Expedition at north-east Greenland. Meddelelser
om Grønland 45: 341–396
Kubota S (1979) Occurrence of a commensal hydroid
Eugymnanthea inquilina Palombi from Japan. Journal of the
Faculty of Science, Hokkaido University, Series VI, Zoology,
21(4): 396–406
Kubota S (1983) Studies on life history and systematics of the
Japanese commensal hydroids living in bivalves, with some
reference to their evolution. Journal of the Faculty of
Science, Hokkaido University, Series VI, Zoology 23(3):
296–403
Kubota S (1992) Four bivalve-inhabiting hydrozoans in Japan
differing in range and host preference. Scientia Marina
56(2–3): 149–159
Kubota S, Larson RJ (1990) The first record of a bivalve-
inhabiting hydrozoan from USA. Proceedings of the
Japanese Society of Systematic Zoology 41: 1–4
Lamarck JBPA (1816) Histoire naturelle des animaux sans
vertèbres. Tome 2. Verdière, Paris, 568 pp
Lamouroux JVF (1812) Extrait d’un mémoire sur la classification
des polypiers coralligènes non entièrement pierreux. Nouveau
Bulletin des Sciences, par la Société Philomatique de Paris
3: 181–188
Leclère L, Schuchert P, Cruaud C, Couloux A, Manuel M (2009)
Molecular phylogenetics of Thecata (Hydrozoa, Cnidaria)
reveals long-term maintenance of life history traits despite
high frequency of recent character changes. Systematic
Biology 58: 509–526, http://dx.doi.org/10.1093/sysbio/syp044
Hydroids from Japanese tsunami marine debris
439
Levinsen GMR (1893) Meduser, ctenophorer og hydroider fra
Grønlands vestkyst, tilligemed bemærkninger om
hydroidernes systematik. Videnskabelige Meddelelser fra
Dansk Naturhistorisk Forening i Kjøbenhavn, series 5, 4:
143–220
Ling SW (1938) Studies on Chinese Hydrozoa. II. Report on
some common hydroids from the East Saddle Island.
Lingnan Science Journal 17: 175–184
Linnaeus C (1758) Systema naturae per regna tria naturae,
secundum classes, ordines, genera, species cum
characteribus, differentiis, synonymis, locis. Editio decima,
reformata. Laurentii Salvii, Holmiae, 823 pp
Lütken C (1850) Nogle Bemaerkninger om Medusernes
systematiske Inddeling, navnlig med Hensyn til Forbes’s
History of brittish naked-eyed medusae. Videnskabelige
Meddelelser fra den Naturhistoriske Forening i Kjöbenhavn
1850: 15–35
Macgillivray J (1842) Catalogue of the marine zoophytes of the
neighbourhood of Aberdeen. Annals and Magazine of
Natural History 9: 462–469, http://dx.doi.org/10.1080/03745484
209445365
Mattox NT, Crowell S (1951) A new commensal hydroid of the
mantle cavity of an oyster. Biological Bulletin 101: 162–170,
http://dx.doi.org/10.2307/1538383
Miglietta, MP, McNally L, Cunningham CW (2010) Evolution of
calcium-carbonate skeletons in the Hydractiniidae.
Integrative and Comparative Biology 50: 428–435,
http://dx.doi.org/10.1093/icb/icq102
Miglietta MP, Cunningham CW (2012) Evolution of life cycle,
colony morphology, and host specificity in the family
Hydractiniidae (Hydrozoa, Cnidaria). Evolution 66: 3876–
3901, http://dx.doi.org/10.1111/j.1558-5646.2012.01717.x
Millard NAH (1959) Hydrozoa from ship’s hulls and
experimental plates in Cape Town docks. Annals of the South
African Museum 45: 239–256
Mills CE, Calder DR, Marques AC, Migotto AE, Haddock SHD,
Dunn CW, Pugh PR (2007) Combined species list of
hydroids, hydromedusae, and siphonophores. In: Carlton JT
(ed), The Light and Smith manual. Intertidal invertebrates
from central California to Oregon. Fourth edition. University
of California Press, Berkeley, pp 151–168
Mills CE, Sommer F (1995) Invertebrate introductions in marine
habitats: two species of hydromedusae (Cnidaria) native to
the Black Sea, Maeotias inexspectata and Blackfordia
virginica, invade San Francisco Bay. Marine Biology 122:
279–288, http://dx.doi.org/10.1007/BF00348941
Naumov DV (1960) Gidroidy i gidromeduzy morskikh,
solonovatovodnykh i presnovodnykh basseinov SSSR.
Akademiya Nauk SSSR, Opredeliteli po Faune SSSR 70, pp
1–626
Nutting CC (1901) Papers from the Harriman Alaska Expedition.
XXI. The hydroids. Proceedings of the Washington Academy
of Sciences 3: 157–216
Nutting CC (1915) American hydroids. Part III. The
Campanularidae and the Bonneviellidae. Smithsonian
Institution, United States National Museum Special
Bulletin 4(3): 1–126
Pallas PS (1766) Elenchus zoophytorum sistens generum
adumbrationes generaliores et specierum cognitarum
succinctas descriptiones cum selectis auctorum synonymis.
Franciscum Varrentrapp, Hagae, 451 pp, http://dx.doi.org/
10.5962/bhl.title.6595
Park JH (1990) Systematic study on the marine hydroids
(Cnidaria, Hydrozoa) in Korea I. Korean Journal of
Systematic Zoology 6: 71–86
Park JH (1991) Systematic study on the marine hydroids
(Cnidaria: Hydrozoa) in Korea II. The families
Sphaerocorynidae, Eudendriidae, Haleciidae and Lafoëidae.
Korean Journal of Zoology 34: 541–547
Ralph PM (1961) New Zealand thecate hydroids. Part V.—The
distribution of the New Zealand thecate hydroids.
Transactions of the Royal Society of New Zealand, Zoology
1: 103–111
Rho BJ (1967) Marine hydroids from the west and the south sea
of Korea. Korean Culture Research Institute 10: 341–360
Rho BJ, Park JH (1980) A systematic study on the marine
hydroids in Korea 6. Thecata. Journal of Korean Research
Institute for Better Living 25: 15–43
Russell FS (1953) The medusae of the British Isles. Antho-
medusae, Leptomedusae, Limnomedusae, Trachymedusae
and Narcomedusae. Cambridge University Press, Cambridge,
530 pp
Sars M (1846) Fauna littoralis Norvegiae oder Beschreibung und
Abbildungen neuer oder wenig bekannten Seethiere, nebst
Beobachtungen über die Organisation, Lebensweise und
Entwickelung derselben. Heft I. Johann Dahl, Christiania, 94
pp
Schuchert P (2001) Hydroids of Greenland and Iceland (Cnidaria,
Hydrozoa). Meddelelser om Grønland, Bioscience 53: 1–184
Schuchert P (2012) North-west European athecate hydroids and
their medusae. Synopses of the British Fauna, new series, 59,
364 pp
Schuchert P (2013a) The status of Plumularia lagenifera
Allman, 1885 (Cnidaria, Hydrozoa) and related species.
Zootaxa 3613: 101–124, http://dx.doi.org/10.11646/zootaxa.
3613.2.1
Schuchert P (2013b) World Hydrozoa database. Available from:
http://www.marinespecies.org/hydrozoa [last consulted on 14
October 2013]
Schuchert P (2014) High genetic diversity in the hydroid
Plumularia setacea: a multitude of cryptic species or
extensive population subdivision? Molecular Phylogenetics
and Evolution 76: 1–9, http://dx.doi.org/10.1016/j.ympev.2014.
02.020
Stechow E (1913) Hydroidpolypen der japanischen Ostküste. II.
Teil: Campanularidae, Halecidae, Lafoeidae, Campanulinidae
und Sertularidae, nebst Ergänzungen zu den Athecata und
Plumularidae. Abhandlungen der Mathematisch-Physika-
lischen Klasse der Königlichen Bayerischen Akademie der
Wissenschaften, 3, Supplement-Band 2: 1–162
Stechow E (1919) Zur Kenntnis der Hydroidenfauna des
Mittelmeeres, Amerikas und anderer Gebiete, nebst Angaben
über einige Kirchenpauer’sche Typen von Plumulariden.
Zoologische Jahrbücher, Abteilung für Systematik,
Geographie und Biologie der Tiere 42: 1–172
Stechow E (1921) Neue Genera und Species von Hydrozoen und
anderen Evertebraten. Archiv für Naturgeschichte, Abteilung
A. 3. Heft, 87: 248–265
Stechow E (1923) Die Hydroidenfauna der japanischen Region.
Journal of the College of Science, Imperial University of
Tokyo 44(8): 1–23
Stechow E (1931) Neue Hydroiden von der Mutsu-Bai,
Nordjapan. Zoologischer Anzeiger 96(78): 177–187
Stechow E, Uchida T (1931) Report of the biological survey of
Mutsu Bay. 21. Hydroiden von Mutsu-Bai, Nord-Japan.
Science Reports of the Tôhoku Imperial University (Biology),
series, 4, 6: 545–571
Tolley SG, Evans III JT, Burghart SE, Winstead JT, Volety AK
(2010) Role of freshwater inflow and salinity on population
regulation in the hydrozoan inquiline symbiont Eutima sp.
Bulletin of Marine Science 86: 625–636
Torrey HB (1902) The Hydroida of the Pacific coast of North
America, with especial reference to the species in the
collection of the University of California. University of
California Publications, Zoology 1: 1–105
D.R. Calder et al.
440
Trask JB (1857) On nine new species of zoophytes from the Bay
of San Francisco and adjacent localities. Proceedings of the
California Academy of Natural Sciences 1: 100–103
Uchida T (1925) Some hydromedusae from northern Japan.
Japanese Journal of Zoology 1: 77–100
Van Beneden PJ (1844a) Sur les genres Eleuthérie et Synhydre.
Bulletins de l’Académie Royale des Sciences et Belles-Lettres
de Bruxelles 11(2): 305–314
Van Beneden PJ (1844b) Recherches sur l’embryogénie des
tubulaires, et l’histoire naturelle des différents genres de cette
famille qui habitent la Côte d’Ostende. Nouveaux Mémoires
de l’Académie Royale des Sciences et Belles-Lettres de
Bruxelles 17(6): 1–72
Van Beneden PJ (1847) Un note sur le mode de reproduction des
animaux inférieurs. Bulletin de l’Académie Royale des
Sciences, des Lettres et des Beaux-Arts de Belgique 14(1):
448–462
Vervoort W, Watson JE (2003) The marine fauna of New
Zealand: Leptothecata (Cnidaria: Hydrozoa) (thecate
hydroids). National Institute of Water and Atmospheric
Research Biodiversity Memoir 119: 1–538
von Lendenfeld R (1883) Eine ephemere Eucopide.
Zoologischer Anzeiger 6: 186–189
Watson J (1985) The genus Eudendrium (Hydrozoa: Hydroida)
from Australia. Proceedings of the Royal Society of Victoria
97: 179–221
Wei Ch (1959) Preliminary research report on hydroids and
medusae of the Zhoushan area. Hangzhou University Journal
1959: 189–212 (Chinese)
Yamada M (1959) Hydroid fauna of Japanese and its adjacent
waters. Publications from the Akkeshi Marine Biological
Station 9: 1–101
... In the years since the devastating 2011 Great East Japan earthquake and tsunami, it has become evident that hundreds of coastal species from Japan have crossed the Pacific Ocean in association with tsunami debris, including species known previously to be invasive and cause ecosystem and economic impacts elsewhere (Choong et al., 2012;Calder et al., 2014;Carlton et al., 2017). As of January 2017, we documented the arrival of > 630 debris items with living organisms. ...
... A monumental effort by many researchers and taxonomists generated a comprehensive list of species associated with Japanese Tsunami Marine Debris (JTMD). Although taxonomic identification and genetic verification is ongoing, nearly 300 taxa of invertebrates and protists have been documented on JTMD collected along the Pacific coast of North America and the Hawaiian Archipelago since 2012 (Choong et al., 2012;Calder et al., 2014;Carlton et al., 2017). While the movement of marine species around the globe through anthropogenic activities, such as ships' ballast water and hull fouling, has been a concern for some time (Carlton and Geller, 1993;Carlton, 1996;Ruiz et al., 1997;Callaway et al., 2006), the transport of such large numbers of marine species across an ocean basin on debris appears to be a new phenomenon that has not been documented previously. ...
Article
Full-text available
Nearly 300 coastal marine species collected from >630 debris items from the 2011 Great East Japan earthquake and tsunami have landed alive along the North American Pacific coast and the Hawaiian Archipelago. We synthesized life history, environmental, and distributional traits for 103 of these species and compared species with (n=30) and without (n=62) known invasion histories. The species represent 12 phyla, and Mollusca, Crustacea, and Bryozoa accounted for 71 of the 103 species. The majority are native to the Northwest Pacific and the Central Indo-Pacific. Species with known invasion history were more common on artificial and hardpan substrates, in temperate reef, fouling, and flotsam habitats, at subtropical and tropical temperatures, and exhibited greater salinity tolerance than species with no prior invasion history. Thirty-five Japanese tsunami marine species without prior invasion history overlapped in ordination trait space with known invaders, indicating a subset of species in this novel assemblage that possess traits similar to species with known invasion history.
... In addition to the documented free-living invertebrate NIS on JTMD thus far, parasite and disease organisms entrained with JTMD or its associated species that would otherwise lack a potential invasion vector could pose additional risks to Pacific North American ecosystems. The high risk species Mytilus galloprovincialis and its hydroid parasite Eutima were both detected on JTMD objects (Calder et al., 2014;G. Ruiz, unpublished data) and assessed here. ...
Article
Full-text available
Marine debris from the Great Tsunami of 2011 represents a unique transport vector for Japanese species to reach Pacific North America and Hawaii. Here we characterize the invasion risk of invertebrate species associated with tsunami debris using a screening-level risk assessment tool - the Canadian Marine Invasive Screening Tool (CMIST). Higher-risk invertebrate invaders were identified for each of five different ecoregions. Some of these are well-known global invaders, such as the mussel Mytilus galloprovincialis and the ascidian Didemnum vexillum which already have invasion histories in some of the assessed ecoregions, while others like the sea star Asterias amurensis and the shore crab Hemigrapsus sanguineus have yet to invade large portions of the assessed ecoregions but also are recognized global invaders. In general, the probability of invasion was lower for the Gulf of Alaska and Hawaii, in part due to lower climate matches and the availability of other invasion vectors.
... An unexpected outcome of the tragic 2011 Great East Japan earthquake and ensuing tsunami was that many living species of algae, invertebrates, and fish (> 320) were transported > 6000 km on or associated with tsunami-related debris items and made landfall in the Northeast Pacific and along the Hawaiian Archipelago. Although there are numerous known natural and anthropogenic vectors that can transport marine species relatively long distances (Helmuth et al., 1994;Ruiz et al., 1997;Thiel and Haye, 2006;Fraser et al., 2011), there is far less information on marine debris as a transoceanic transport vector for potentially invasive species (Thiel and Gutow, 2005a;Gregory, 2009;Goldstein et al., 2014;Kiessling et al., 2015) and almost no information on tsunami-generated debris (Calder et al., 2014;Carlton et al., 2017). In fact, it was not until June 2012, when a large dock from Misawa, Japan that was torn loose during the tsunami landed on a beach in Oregon with > 100 living species and many 1000s of individuals that the potential for the Great East Japan tsunami to create a flotilla of well-constructed transport vectors was fully recognized. ...
Article
Full-text available
Biofouled debris from the 2011 Great East Japan earthquake and tsunami has landed in the Northeast Pacific and along the Hawaiian Islands since 2012. As of 2017, >630 biofouled debris items with >320 living species of algae, invertebrates, and fish have been examined. The invasive mussel Mytilus galloprovincialis was present on >50% of those items. Size, reproduction, and growth of this filter-feeding species were examined to better understand long-distance rafting of a coastal species. The majority of mussels (79%) had developing or mature gametes, and growth rates averaged 0.075±0.018 SE mm/day. Structural and elemental (barium/calcium) analysis of mussel shells generated estimates of growth in coastal waters (mean=1.3 to 25mm total length), which provides an indication of residence times in waters along North America and the Hawaiian Islands prior to landing. Detailed studies of individual species contribute to our understanding of debris as a transport vector and aid efforts to evaluate potential risks associated with marine debris.
... This lack of knowledge of the Japanese marine algal flora also led West et al. (2016) to demure on the origin of a new genus and species of Stylonematophyceae found on plastic Japanese tsunami debris that washed ashore in Oregon and Washington in 2015 and 2016. A similar level of taxonomic uncertainty was noted by Calder et al. (2014), who examined the hydroids on Japanese tsunami derelict boats and docks that washed ashore in Oregon and Washington in 2012 and 2013. It is important that the present undescribed species of Pyropia be documented in Japan, and it is preferable that it be described from its native habitat there. ...
... Adding to this menu are other emerging vectors that also remain poorly assessed, such as the increasing amount of marine debris (long-lasting floating substrates, such as plastic, styrofoam, and fiberglass, which may significantly alter the natural transoceanic dispersal of many species (Barnes, 2004;Barnes & Milner, 2005;Godwin et al., 2008;Gregory, 2009). A recent example is the debris field generated by the 2011 Tōhoku Earthquake and Tsunami, leading to the dispersal of Japanese species across the North Pacific Ocean to North America and the Hawaiian Islands (Calder et al., 2014). Other vectors arise as unintended consequences of various endeavors (such as species attaching to and being dispersed on tracking bands of migratory birds (Tottrup et al., 2010) and marine mammals (Reisinger et al., 2009), as well as the movement of scientific sampling gear between hydrothermal vents (Voight et al., 2012). ...
... Obelia dichotoma is mainly distinguished from O. longissima by its branching patterns and shape of the hydrothecal rim (Cornelius, 1990Cornelius, , 1995b), but our analysis shows these characters are not informative for the delimitation of the species. In fact, further discriminations of these characters have recently corroborated the revalidation of former synonyms of O. dichotoma (Calder, 2013; Calder et al., 2014), and this might also prove to be the case for the cryptic lineages of O. dichotoma presented in this study. ...
Article
Full-text available
Currently, the seashore is threatened by the environment of climate change and increasing coastal waste. The past environmental groups used a large amount of manpower to manage the coast to maintain the seashore environment. The computational time cost and efficiency are not ideal for the vast area of the seashore. With the progress of GIS (Geographic Information System) technology, the ability of remote sensing technology can capture a wide range of data in a short period. This research is based on the application of remote sensing technology combined with machine learning to display the observation of our seashore. However, in the process of image classification, the seashore wastes are small, which required the use of high-resolution image data. Thus, how to remove the noise becomes a crucial issue in developing an image classifier machine. The difficulties include how to adjust the value of parameters for removing/avoiding noises. First, the texture information and vegetation indices were employed as ancillary information in our image classification. On the other hand, auto-encoder is a very good tool to denoise a given image; hence, it is used to transform high-resolution images by considering ancillary information to extract attributes. Multi-layer perceptron (MLP) and support vector machine (SVM) were compared for classifier performance in a parallel study. The overall accuracy is about 85.5% and 83.9% for MLP and SVM, respectively. If the AE is applied for preprocessing, the overall accuracy is increased by about 10–12%.
Article
We analysed hydromedusa assemblages of South America (from 22°S to 56°S and from 040°W to 080°W), their association with water masses and the influence of the life cycle on medusa distributions. The geographic distribution of 130 species of hydromedusae was compiled from literature reports (62 publications between 1913 and 2012). Seven areas were defined: Atlantic Magellanic, Argentinean, Pacific intermediate zone, Pacific Magellanic, Peruvian–Chilean, South Brazilian and Oceanic. The variance of the species–environment relationship was explained by depth and temperature. Distribution patterns of Atlantic hydromedusae are associated with neritic water masses, supporting previously proposed biogeographical provinces. Assemblages on the Pacific side of South America are under the influence of the Humboldt Current system, with a break in species distribution around Chiloé Island. Only the oceanic assemblage contained the same species in both the Pacific and Atlantic zones. We found that meroplanktonic medusae contributed more to define the neritic assemblages, while the oceanic assemblage was better defined by holoplanktonic medusae. Therefore, our data suggest that meroplanktonic hydromedusae appeared to be more restricted in distribution than holoplanktonic ones.
Chapter
Full-text available
The abundance and distribution of plastic debris in the marine environment show patterns of near- and offshore generation, migration toward and accumulation in the subtropical gyres, fragmentation, and redistribution globally. Ecological impacts in the subtropical gyres include invasive species transport and rampant ingestion and entanglement; yet plastics have also created substantial new habitat, resulting in population increases in some species. Though estimates of surface abundance and weight indicate over a quarter million tons and particle counts in the trillions, there is also a rapid removal of microplastics from the sea surface. Recent studies show widespread occurrence of these microplastics throughout the vertical column and in benthic and coastal sediments. It is likely that sedimentation is the ultimate fate for plastic lost at sea. Before microplastics sink, they likely cause significant impacts to marine food chains and ecosystems. In the open ocean, plastics are mingled with marine communities, making removal at sea prohibitive. This new understanding informs mitigation efforts to divert attention away from open-ocean cleanup. Similar to the way societies dealt with widely distributed particulate contamination in the air above cities, the “smog” of microplastics destined to pass through marine ecosystems before finally settling on the seafloor is best addressed with preventative measures.
Article
Hydroid species assemblages were studied and characterized for 12 marine ecological systems around Bermuda. Species numbers were highest inshore in environments exposed to tidal currents and waves, such as inlets, sounds, and marine caves, and offshore on deeper coastal substrates (25-100 m). Diversity was lowest in still-water systems, including sheltered areas of bays and anchialine ponds. Two major groupings representing a dichotomy between shallow (<25 m) and deep (>25 m) systems were distinguished. Of the 90 hydroid species considered in zoogeographic analyses, more than half are circumglobal in warm coatal waters. The hydroids of Bermuda have a strong affinity with those of the Caribbean and West Indies. Endemism is low among Bermudian hydroids in spite of the isolation and old geologic age of the island. Warm-water species inhabiting the Bermuda Platform probably colonized the area during the Holocene because the Bermudian marine climate at times during the Pleistocene was temperate rather than tropical or subtropical. Rafting of sessile stages is suggested as the most significant means by which hydroid species have been introduced to this remote oceanic island. -from Author
Article
Seventeen species of Eudendrium, including 10 newly described, are reported. Most of the species are recorded from the E and SE coastline; only 4 are known from Western Australia and none from the Northern Territory, Tasmania or the Great Australian Bight.-from Author
Article
This memoir deals with the New Zealand Leptolida Leptothecatae (formerly named Hydroida Thecaphora, also referred to as Hydroida Leptomedusae and colloquially known as thecate hydroids), based on collections of the New Zealand Oceanographic Institute (now incorporated in NIWA - the National Institute of Water and Atmospheric Research), Wellington; the National Museum of New Zealand Te Papa Tongarewa, Wellington; the Otago Museum, Dunedin; and the Portobello Marine Biological Station of the University of Otago, Dunedin. About 300 species are discussed and where necessary described and figured. This group of animals was the subject of a thorough survey by Dr Patricia M. Ralph in the years 1957-1961 but largely based on shore-based collections, only a small portion of her material coming from deeper waters. The present survey covers a much wider area, extending into deep waters and dealing with a greatly increased number of species. In many cases the number of specimens studied was much larger than the comparatively modest number of samples at Dr Ralph's disposal, so our views in certain cases differ from hers. Nevertheless we have closely followed Dr Ralph's discussion, having access to the major part of her collections. The number of new species in the extensive collections is considerable, some 45 being described. The taxonomic part of the present report is preceded by introductory paragraphs including an historical introduction, a paragraph highlighting the general structure of Leptothecatae and a glossary.