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Schizoporella japonica
(orange ripple bryozoan)

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Datasheet

Schizoporella japonica (orange ripple bryozoan)

Summary

  • Last modified
  • 08 February 2019
  • Datasheet Type(s)
  • Invasive Species
  • Preferred Scientific Name
  • Schizoporella japonica
  • Preferred Common Name
  • orange ripple bryozoan
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Bryozoa
  •       Class: Gymnolaemata
  •         Order: Cheilostomatida
  • Summary of Invasiveness
  • The incrusting bryozoan Schizoporella japonica was originally described from Japan. In the middle of the 20th century, S. japonica was introduced to the Pacific coast of North America, where it is now...

  • Principal Source
  • Draft datasheet under review

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Pictures

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PictureTitleCaptionCopyright
Schizoporella japonica; habit at day 1 settlement.
TitleDay 1
CaptionSchizoporella japonica; habit at day 1 settlement.
Copyright©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; habit at day 1 settlement.
Day 1Schizoporella japonica; habit at day 1 settlement.©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; habit at day 2 settlement.
TitleDay 2
CaptionSchizoporella japonica; habit at day 2 settlement.
Copyright©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; habit at day 2 settlement.
Day 2Schizoporella japonica; habit at day 2 settlement.©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; habit at day 4 settlement
TitleDay 4
CaptionSchizoporella japonica; habit at day 4 settlement
Copyright©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; habit at day 4 settlement
Day 4Schizoporella japonica; habit at day 4 settlement©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; habit at day 7 settlement.
TitleDay 7
CaptionSchizoporella japonica; habit at day 7 settlement.
Copyright©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; habit at day 7 settlement.
Day 7Schizoporella japonica; habit at day 7 settlement.©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; habit at day 10 settlement.
TitleDay 10
CaptionSchizoporella japonica; habit at day 10 settlement.
Copyright©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; habit at day 10 settlement.
Day 10Schizoporella japonica; habit at day 10 settlement.©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; colony morphology at day 7. Anatomy of Schizoporella japonica.  Ancestrula - the zooid which arises from the larva after settlement; the original zooid before asexual reproduction begins.  Zooecium - the encasing material which houses the body of the zooid.  Lophophore - a ring of ciliated tentacles surrounding the mouth used for feeding; may be extended or retracted.  Operculum (pl. Opercula) - the hole from which the lophophore emerges.
TitleColony morphology
CaptionSchizoporella japonica; colony morphology at day 7. Anatomy of Schizoporella japonica. Ancestrula - the zooid which arises from the larva after settlement; the original zooid before asexual reproduction begins. Zooecium - the encasing material which houses the body of the zooid. Lophophore - a ring of ciliated tentacles surrounding the mouth used for feeding; may be extended or retracted. Operculum (pl. Opercula) - the hole from which the lophophore emerges.
Copyright©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; colony morphology at day 7. Anatomy of Schizoporella japonica.  Ancestrula - the zooid which arises from the larva after settlement; the original zooid before asexual reproduction begins.  Zooecium - the encasing material which houses the body of the zooid.  Lophophore - a ring of ciliated tentacles surrounding the mouth used for feeding; may be extended or retracted.  Operculum (pl. Opercula) - the hole from which the lophophore emerges.
Colony morphologySchizoporella japonica; colony morphology at day 7. Anatomy of Schizoporella japonica. Ancestrula - the zooid which arises from the larva after settlement; the original zooid before asexual reproduction begins. Zooecium - the encasing material which houses the body of the zooid. Lophophore - a ring of ciliated tentacles surrounding the mouth used for feeding; may be extended or retracted. Operculum (pl. Opercula) - the hole from which the lophophore emerges.©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; colony morphology at day 10.  Anatomy of Schizoporella japonica.  Ancestrula - the zooid which arises from the larva after settlement; the original zooid before asexual reproduction begins.  Zooecium - the encasing material which houses the body of the zooid.  Lophophore - a ring of ciliated tentacles surrounding the mouth used for feeding; may be extended or retracted.  Operculum (pl. Opercula) - the hole from which the lophophore emerges.
TitleColony morphology
CaptionSchizoporella japonica; colony morphology at day 10. Anatomy of Schizoporella japonica. Ancestrula - the zooid which arises from the larva after settlement; the original zooid before asexual reproduction begins. Zooecium - the encasing material which houses the body of the zooid. Lophophore - a ring of ciliated tentacles surrounding the mouth used for feeding; may be extended or retracted. Operculum (pl. Opercula) - the hole from which the lophophore emerges.
Copyright©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html
Schizoporella japonica; colony morphology at day 10.  Anatomy of Schizoporella japonica.  Ancestrula - the zooid which arises from the larva after settlement; the original zooid before asexual reproduction begins.  Zooecium - the encasing material which houses the body of the zooid.  Lophophore - a ring of ciliated tentacles surrounding the mouth used for feeding; may be extended or retracted.  Operculum (pl. Opercula) - the hole from which the lophophore emerges.
Colony morphologySchizoporella japonica; colony morphology at day 10. Anatomy of Schizoporella japonica. Ancestrula - the zooid which arises from the larva after settlement; the original zooid before asexual reproduction begins. Zooecium - the encasing material which houses the body of the zooid. Lophophore - a ring of ciliated tentacles surrounding the mouth used for feeding; may be extended or retracted. Operculum (pl. Opercula) - the hole from which the lophophore emerges.©Akiko Onuma/Settling invertebrates of the Oregon Coast - http://akiko-invertebrates.weebly.com/index.html

Identity

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Preferred Scientific Name

  • Schizoporella japonica Ortmann, 1890

Preferred Common Name

  • orange ripple bryozoan

Other Scientific Names

  • Schizoporella unicornis Johnston in Wood, 1844
  • Schizoporella unicornis var. japonica Ortmann, 1890

Summary of Invasiveness

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The incrusting bryozoan Schizoporella japonica was originally described from Japan. In the middle of the 20th century, S. japonica was introduced to the Pacific coast of North America, where it is now well established. In 2010, the species was recorded for the first time in European waters in North Wales and in 2011 in the Orkney Islands and other localities in northern Scotland. These introductions seem most likely to have occurred through an ocean-going vessel or to have been transported with oysters. The bryozoan species colonizes freely available substratum, including artificial underwater structures and vessel hulls, with colonies rapidly becoming extensive and sometimes dominating fouling assemblages. The species has high competitive ability and shows high abundance and dominance in harbours. Long term confusion of S. japonica with other Schizoporella species has generated uncertainty regarding the extent of native and introduced ranges of the group, indicating that S. japonica may be much more widely distributed than what has been suggested until now.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Bryozoa
  •             Class: Gymnolaemata
  •                 Order: Cheilostomatida
  •                     Family: Schizoporellidae
  •                         Genus: Schizoporella
  •                             Species: Schizoporella japonica

Notes on Taxonomy and Nomenclature

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More than 50 recent bryozoan species have been placed in the genus Schizoporella, including nine European species (Zabala and Maluquer, 1988; Hayward and Ryland, 1999; Tompsett et al., 2009; Bock, 2015; WoRMS, 2015). These species are spread throughout the world’s oceans, being present in all climatic zones, from polar to tropical regions (Marcus, 1940; Hayward and Ryland, 1995), and inhabiting virtually all kinds of substrata. The species S. japonica by Ortmann (1890) was originally described as S. unicornis var. japonica using specimens collected by Dr. L. Döderlein, in 1880-1881, from Sagami Bay, Honshu, Japan. Its holotype is stored in Strasbourg Museum (Ryland et al., 2014). Over the years there has been extensive confusion between this and other Schizoporella species, commonly S. errata, S. unicornis and S. pseudoerrata (Ryland et al., 2014). S. unicornis var. japonica has recently been elevated to species status as S. japonica by Dick et al. (2005).

Description

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Detailed descriptions of S. japonica can be found in Ortmann (1890) and Grischenko et al. (2007) for Japan, in Dick et al. (2005) for the Pacific coast of America and in Ryland et al. (2014) for Northern Europe. Bryozoan morphology varies according to environmental conditions and geographic area where species are collected (Ryland et al., 2014).

S. japonica forms an encrusting heavily calcified colony consisting, at first, of more or less circular flat sheets, which later may become bi-layered, occasionally with foliose lobes free from substrate or overgrowing other colony. Colonies spread over rocks, shells and other substrata, rapidly becoming extensive, pale whitish-pink to vivid orange-red or deep red in colour. Individual animals within a colony are called zooids. Zooids represent a living polypide inside a non-living case called zooecium. The walls of bryozoan zooecia are strengthened with a variety of substances depending on the species, normally calcium carbonate, chitin or a mixture of both. Morphology of zooecia is important for identification of the species. S. japonica zooids are generally rectangular, rounded distally, arranged in columns radiating from the centre, quite variable in size, usually 0.48-0.90 mm long. Each polypide is connected to its nearest neighbours by a strand of living tissue called protoplasm. Each zooecium has a hole at the top, called an orifice, through which the polypide can extend its ring of tentacles, or lophophore, when it is feeding. The orifice can be sealed by an operculum and occasionally by perforated calcification. The orifice of S. japonica is broader than long, semi-circular on the distal side. There is often a small umbo (knob) below the orifice. Avicularia may be distinguished near the orifice and have protective function. On a given zooid, oral avicularia may be absent, single or paired. Morphology of avicularia is important for species distinction; for detailed morphology of S. japonica avicularia see Dick et al. (2005). The zooecium contains a compensation sac (ascus) in its interior, immediately beneath the calcified front. This sac acts as a reservoir and allows internal volume changes (necessary because the zooecium is otherwise rigid) and opens to the exterior via a notch (sinus vanna) in the proximal rim of the orifice. S. japonica, together with S. errata, S. pseudoerrata and S. unicornis, has broadly and shallowly U-shaped sinus, wider than deep. Zooids can specialise morphologically, being responsible for specific tasks. Autozooids are specialised in feeding or collecting food, with slightly to moderately convex, evenly perforated, frontal walls. Vertical walls have uniporous or multiporous septula (Hayward and Ryland, 1999). In all colonies, a large percentage of zooids are autozooids, and some colonies consist entirely of autozooids, some of which also engage in reproduction. Feeding polypides of S. japonica (the internal living movable parts) have a lophophore of ciliated tentacles (about 19 tentacles in specimens from Friday Harbor, USA), which generate a water current that traps small particles of food and diverts them to the digestive tract. The digestive tract consists of a pharynx, a stomach and a U-shaped gut that terminates in an anus. The nervous system is composed of a single bilobed ganglion at the base of the lophophore near the pharynx. Ovicells are zooids specialized in reproductive activities. They act as brood chambers, producing eggs and holding them safe until they are ready to hatch. They look like a helmet, or hood, on the anterior end of some zooids. In S. japonica, ovicells are raised, conspicuous, resting on the frontal wall of the succeeding zooid, globose, 0.28-0.40 mm long by 0.28-0.40 mm wide, with scattered small pores over the entire surface and heavy ribs converging from the margin towards the midline.

Distribution

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As differences between Schizoporella species can be subtle (Tompsett et al., 2009), certain species had been assumed to have cosmopolitan ranges. However, it is now recognized that, in many instances, this is probably not the case (Dick et al., 2005; Ryland et al., 2014). For example, S. unicornis has been repeatedly reported from the Pacific coast of North America; however, these records likely refer to S. japonica. It is also possible that many records from the Northeast Pacific are based on the misidentification of S. japonica, S. pseudoerrata and S. errata (Dick et al., 2005; Ryland et al., 2014). Similarly, records of S. unicornis from Australia (Ross and McCain, 1976; Vail and Wass, 1981; Tzioumis, 1994) should be considered with caution. These may instead represent populations of S. japonica introduced on oyster seed that were transplanted from Japan to Australia in the mid-1900s (Dick et al., 2005).

The first case of S. japonica invasion in European waters was recorded in a marina at Holyhead, North Wales, in July 2010. From May 2011, the species was found abundantly in the Orkney Islands and, subsequently, at other localities in northern Scotland (Ryland et al., 2014). The authors have no evidence to suggest whether Japan or North America was the source for this invasion. S. japonica is now widespread in the UK and has also been recorded in Ireland and Norway (see review in Loxton et al., 2017).

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Sea Areas

Atlantic, NortheastPresentIntroduced Invasive Ryland et al., 2014; Loxton et al., 2017
Pacific, Eastern CentralPresentIntroducedOsburn, 1952; Powell, 1970; Ryland et al., 2014
Pacific, NortheastPresentIntroducedRoss and McCain, 1976; Thorpe and Ryland, 1987; Dick et al., 2005
Pacific, NorthwestPresentNativeOrtmann, 1890; Grischenko et al., 2010; Grisсhenko and Zvyagintsev, 2012; Ryland et al., 2014

Asia

ChinaPresentLiu et al., 2001As S. unicornis
JapanPresentNativeMawatari and Mawatari, 1980As S. unicornis
-HokkaidoPresentNativeKubota and Mawatari, 1985; Grischenko et al., 2007; Ryland et al., 2014
-HonshuPresentNativeOkada, 1929As S. unicornis; Mutsu Bay

North America

CanadaPresentIntroducedPresent based on regional distribution
-British ColumbiaPresentIntroducedPowell, 1970As S. unicornis; from San Juan Islands, Vancouver Island, and Pendrell Sound
USAPresentIntroducedPresent based on regional distribution
-AlaskaWidespreadIntroduced2003Dick et al., 2005Higgins Point, East Tongass Narrows, Ketchikan
-CaliforniaPresentIntroducedPowell, 1970; Ryland et al., 2014
-WashingtonPresentIntroduced Invasive Ross and McCain, 1976; Thorpe and Ryland, 1987

Europe

IrelandPresentIntroduced Invasive Loxton et al., 2017
NorwayPresentIntroducedLoxton et al., 2017
Russian FederationPresentPresent based on regional distribution
-Russian Far EastPresentGrisсhenko and Zvyagintsev, 2012Near Vladivostok
UKPresentIntroduced Invasive Ryland et al., 2014; Loxton et al., 2017

Oceania

AustraliaUnconfirmed recordRoss and McCain, 1976; Vail and Wass, 1981; Tzioumis, 1994

History of Introduction and Spread

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Osburn (1952) was the first to report S. unicornis in California, finding it common in bays where oysters from the Atlantic coast had been introduced. However, Osburn’s records are now known to have been based on a mixture of S. japonica, S. errata and S. pseudoerrata (Powell, 1970; Soule et al., 1995). Powell (1970) also reported a Schizoporella species (identified as S. unicornis, but likely S. japonica) to be present in Newport Bay, Los Angeles, as long ago as 1938. The same author refers to additional material from Newport collected in 1943, from Morro Bay, California, collected in 1968, from several stations in the San Juan Islands and from Canada (Strait of Georgia,, Vancouver Island and as far north as Pendrell Sound). This range was extended to further localities in Washington State and later in San Francisco Bay in 1977 (Ross and McCain, 1976; Ryland et al., 2014). From 1998, the species has been found in Alaska, in the areas of Ketchikan, Sitka, and Valdez and Tatilek, Prince William Sound (Hines and Ruiz, 2000; Dick et al., 2005; Ruiz et al., 2006). All these authors argue that the species has been introduced from Japan in the early to mid-1930s, along with the Pacific oyster Crassostrea gigas, rather than from the Atlantic.

Risk of Introduction

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It is likely that S. japonica will continue to spread in European waters (Ryland et al., 2014). Furthermore, because some records of S. unicornis in Australia may actually correspond to S. japonica (Dick et al., 2005), a possibility of invasion in that region is feasible.

Habitat

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In the native range (Akkeshi Bay, Japan), the species has been reported from rocks (approximately 87% of the samples) and shells on the sublittoral (Grischenko et al., 2007; Grisсhenko and Zvyagintsev, 2012).

In the invaded range (North Wales, UK), the species has been found just below the waterline on floating structures, such as plastic fenders, mooring buoys, or the vertical walls of pontoons (Ryland et al., 2014). Most authors suggest that S. japonica is a typical fouling species. However, at East Tongass Narrows (Alaska, USA), Dick et al. (2005) reported colonies of S. japonica covering square metres of exposed benchrock and occupying large portions of the undersides of boulders. Similarly, Powell (1970) reported collecting ‘‘massive colonies’’ of this species (which he reported as S. unicornis) intertidally on the underside of boulders and on dead eroded oyster shells.

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Littoral
Intertidal zone Principal habitat Harmful (pest or invasive)
Intertidal zone Principal habitat Natural

Biology and Ecology

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Reproductive Biology

New bryozoan colonies are usually started by individuals resulting from sexual reproduction. All known bryozoans are hermaphrodite. Brooding takes place in an ovicell. The developing egg appears to derive nutrition from its parent zooid because, if removed, the egg dies. Eventually the ciliated larva escapes and, after its planktonic existence, the larva settles onto a substrate and develops into the first animal stage, which is called ancestrula. Ancestrula of S. japonica (size 350-400 x ~300 μm) have D-shaped orifices and eight marginal spines (Ryland et al., 2014). After a short period of growth, the bryozoan begins to reproduce asexually (by budding), forming a circular colony.

Physiology and Phenology

According to Ryland et al. (2014), S. japonica is a cold-water species, which breeding season in Britain extends through the winter. According to their observations, embryos of S. japonica from UK waters (Holyhead, Wales) are reddish, apparently increasing in size during development; half-sized embryos are present even in midwinter (February). In the Strait of Georgia (Canada), the breeding season of S. japonica occurs all year round, with the species showing higher level of fecundity than other local bryozoans (Powell, 1970).

Population Size and Density

In North Wales, colony dimensions range from less than 1 cm up to 20 cm (Ryland et al., 2014).

Nutrition

Bryozoans are filter-feeding animals. Feeding polypides capture food particles from the water through a "crown" of hollow tentacles called lophophore. Food particles are trapped by mucus and conveyed towards the mouth, which lies in the centre of the base of the lophophore. Detritus and plankton are digested in the U-shaped gut running from the mouth, in the centre of the lophophore, down into the animal's interior and then back to the anus.

Environmental Requirements

In its natural range (Akkeshi Bay, Japan), S. japonica withstands water temperatures from -1.4 to 21°C and salinity ranging from 26 to 31 ppt (Grischenko et al., 2007). Powell et al. (1970) noted that S. japonica (recorded as S. unicornis) occurred in hyposaline waters, in salinities down to 15 ppt.

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
34-63

Water Tolerances

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ParameterMinimum ValueMaximum ValueTypical ValueStatusLife StageNotes
Salinity (part per thousand) 15 to 31 ppt tolerated
Water temperature (ºC temperature) -1.4 to 21°C tolerated

Pathway Causes

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CauseNotesLong DistanceLocalReferences
HitchhikerOn oysters Yes Powell, 1970
Interbasin transfersOn vessels hulls Yes Yes Ryland et al., 2014

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Aquaculture stockOn oysters Yes Powell, 1970
Ship ballast water and sediment Yes Yes Ryland et al., 2014
Ship hull fouling Yes Yes Ryland et al., 2014

Economic Impact

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The species is able to colonize most freely available substrata, including artificial underwater structures and vessel hulls, sometimes dominating fouling assemblages (Tzioumis, 1994). This fouling can be a nuisance to shipping and ports, and has the potential to become a problem to industrial components, cooling vents, etc., as is the case for other bryozoans.

When associated with oysters, the species does not seem to harm commercial aquaculture, as colonies prefer to live on dead eroded shells, rather than on living oysters (Powell, 1970). However, when they do, this reduces bivalve commercial value. S. japonica can also become a significant fouler of bivalve aquaculture gear.

Environmental Impact

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Impact on Biodiversity

S. japonica is a significant competitor for space and resources, known to inhibit growth of adjacent species.

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Abundant in its native range
  • Highly adaptable to different environments
  • Is a habitat generalist
  • Capable of securing and ingesting a wide range of food
  • Has high reproductive potential
  • Gregarious
  • Reproduces asexually
Impact outcomes
  • Infrastructure damage
  • Negatively impacts aquaculture/fisheries
Impact mechanisms
  • Competition
  • Fouling
  • Rapid growth
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Difficult to identify/detect as a commodity contaminant
  • Difficult to identify/detect in the field
  • Difficult/costly to control

Detection and Inspection

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According to Ryland et al. (2014), the species can be photographed in situ, and collected by scraping and lifting with a knife. For the study of skeleton components, specimens can be treated with diluted hypochlorite bleach for 24-48 h in order to remove non-calcified tissue, and then cleaned by ultrasound via optical (transmitted light) and scanning electron (SEM) microscopy. Protocols for preparation of Schizoporella material for SEM can be found in Tompsett et al. (2009).

Similarities to Other Species/Conditions

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The genus Schizoporella can be identified by its sinuate primary orifice, single or paired adventitious avicularia lateral to the orifice, frontal shield with areolae and pseudopores and prominent ovicells. However, differences between species of the genus can be subtle and very few of them have been described by modern standards (Tompsett et al., 2009), which has caused confusion about the geographic ranges of S. japonica and other Schizoporella species worldwide. The main characters traditionally used for species separation in this genus are size, budding pattern and layering of the colony, shape of the orifice and sinus, appearance of the porous frontal wall, and morphology of the ovicell, especially ribbing and distribution of pores. Full comparisons between S. japonica and S. unicornis in Europe and between S. japonica, S. errata and S. pseudoerrata in North American localities have been performed by Ryland et al. (2014). Additional comparisons of S. unicornis and S. errata based on scanning electron microscopy analysis may be found in Tompsett et al. (2009). Generally, S. japonica zooids have a much greater length:width ratio than other species. Density of frontal pseudopores also provides a useful discriminatory character.

Knowledge of the geographical range and habitat of the Schizoporella species being studied is often useful for species distinction. S. unicornis can only be confused with S. japonica in the Atlantic coasts of Western Europe, including the British Isles, but not in the Pacific coast of North America, where it has repeatedly been reported in error (Hayward and Ryland, 1999; Ryland et al., 2014). In Europe, the habitat of these two species may differ: S. japonica is so far only known from harbours and marinas, and is a typical fouling species, whereas S. unicornis occurs in non-fouling conditions, on stones, rocks, shells and kelp holdfasts (Ryland et al., 2014). S. errata may be confused with S. japonica on the Pacific coast of America. However, because the former is rather a warm-water species, it is likely to be common south of San Francisco, while the opposite is true for S. japonica (Dick et al., 2005). Although the latter has spread northwards through Canada to southern Alaska, it may extend southwards beyond San Francisco to Morro Bay and (historically, at least) to the Los Angeles area, where confusion between the two species may still occur.

Prevention and Control

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Prevention
No specific prevention methods have been developed for S. japonica. However, general methods of invasive species control and prevention are well known. An European surveillance network and appropriate monitoring strategy are recommended, with the aim to assess risks, impacts and invasiveness of the alien species, as well as the efficiency of its eradication and control measures (Nehring and Klingenstein, 2005). Regulatory international measures against invasions in European Seas are discussed in Gollasch (2006) and risk assessment, methods of preventive treatment and control, and management solutions for ballast water, which can be applied to this species, are discussed elsewhere (Haugom et al., 2002; Taylor et al., 2002; David and Gollash, 2015). Bishop and Hutchings (2011) have evaluated the usefulness of port surveys focused on pest identification for exotic species management. 

Gaps in Knowledge/Research Needs

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The misidentification of Schizoporella species in several ecological studies highlights the need for molecular characterisation of cryptic species complexes. More studies on the ecology of Schizoporella species are needed, which has so far been poorly investigated.

References

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Bishop, M. J., Hutchings, P. A., 2011. How useful are port surveys focused on target pest identification for exotic species management?. Marine Pollution Bulletin, 62(1), 36-42. doi: 10.1016/j.marpolbul.2010.09.014

Bock P, 2015. The Bryozoa homepage. Recent and fossil Bryozoa. http://www.bryozoa.net/

David M, Gollasch S, 2015. Global maritime transport and ballast water management, Issues and Solutions. Invading Nature - Springer Series in Invasion Ecology, Vol. 8, Netherlands: Springer Netherlands.306 pp.

Dick MH, Grischenko AV, Mawatari FS, 2005. Intertidal Bryozoa (Cheilostomata) of Ketchikan, Alaska. Journal of Natural History, 39, 3687-3784.

Gollasch, S., 2006. Overview on introduced aquatic species in European navigational and adjacent waters. Helgoland Marine Research, 60(2), 84-89. doi: 10.1007/s10152-006-0022-y

Grischenko AV, Dick MH, Mawatari SF, 2007. Diversity and taxonomy of intertidal Bryozoa (Cheilostomata) at Akkeshi Bay, Hokkaido, Japan. Journal of Natural History, 41, 1047-1161.

Grischenko AV, Zvyagintsev AY, 2012. On the state of inventory of the bryozoan fauna of Peter the Great Gulf of the Sea of Japan in light of detection of the cheilostome bryozoans Callopora sarae and Microporella trigonellata. Russian Journal of Biological Invasions, 2, 42-54.

Haugom GP, Behrens HL, Andersen AB, 2002. Risk based methodology to assess invasive aquatic species in ballast water. In: Invasive aquatic species in Europe. Distribution, impacts and management, [ed. by Leppakoski E, Gollasch S, Olenin S]. Dordrecht, Netherlands: Kluwer Academic Publishers. 467-476.

Hayward PJ, Ryland JS, 1979. British ascophoran bryozoans: keys and notes for the identification of the species. Issue 14 of Synopses of the British fauna, London, UK: Academic Press Inc.312 pp.

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Links to Websites

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WebsiteURLComment
GISD/IASPMR: Invasive Alien Species Pathway Management Resource and DAISIE European Invasive Alien Species Gatewayhttps://doi.org/10.5061/dryad.m93f6Data source for updated system data added to species habitat list.
National Exotic Marine and Estuarine Species Information System (NEMESIS)http://invasions.si.edu/nemesis/index.html

Principal Source

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Draft datasheet under review

Contributors

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15/05/15 Original text by:

Ekaterina Shalaeva, Consultant, UK

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