Watersipora subatra


Scientific Name: Watersipora subatra

Phylum: Bryozoa

Class: Gymnolaemata

Order: Cheilostomatida

Family: Watersiporidae

Genus: Watersipora


subatra [Describe here as A. iricolor]

Native Distribution

Origin Realm:

Temperate Northern Pacific, Central Indo-Pacific

Native Region:

Origin Location:

Temperate Northern Pacific [Japan] Sagami Bay (Vieira et al 2014) STATUS STATED [Schizoporella aterrima var. subatra (Synonymized taxon)] Sagami Bay, Japan. (Ortman 1890, cited in Vieira et al. 2014) STATUS NOT STATED [Schizoporella cucullata (Synonymized taxon)] Misaki, Sagami Bay, Japan (Vieira et al. 2014) STATUS NOT STATED Central Indo-Pacific [Indonesia] (Vieira et al 2014) STATUS NOT STATED ["Watersipora subovoidea" (Synonymized taxon)] Komodo, Indonesia. (Winston & Hemberg 1986) STATUS NOT STATED

Geographic Range:

[Western Pacific] Japan; Australia and New Zealand; Indonesia (Vieira et al 2014) [Eastern Pacific] US (California) (Vieira et al 2014) [Eastern Atlantic] UK: Ireland and British Isles; France; Germany (Vieira et al 2014; Bishop et al 2015a)

General Diversity:

Cryptic speciation in W. subatra (as W. subtorquata) and a Californian lineage 15% divergent in COI nucleotide sequence from another widespread clade (Ryland et al 2009, cited in Vieira et al 2014) Two genetically shallow groups in W. subatra (as W. subtorquata): clade A in Europe and Australasia, and clade B in California (Mackie et al 2012, cited in Vieira et al 2014)

Non-native Distribution

Invasion History:

Yes, see inv_propens

Non-native Region:

Northeast Atlantic, Northeast Pacific, Southern Australia and New Zealand

Invasion Propens:

Temperate Northern Pacific [USA] California (Vieira et al 2014; Bishop et al 2015b) *Introduced [USA] Point Loma Marina, San Diego, California, USA. (Vieira et al. 2014) *Invasive Temperate Australasia [New Zealand] (Vieira et al 2014; Bishop et al 2015b) *Introduced [New Zealand] [Watersipore subtroquta] Victoria Wharf, Dunedin, and Carey's Bay, Port Chalmers. (Gordon & Mawatari 1992) *Exotic [New Zealand] [Watersipore subtroquta] Port of Wellington, Westhaven Marine in Auckland, , Nelson, Napier. (Gordon & Mawatari 1992) *Exotic [Australia] Mersey Yacht Club and Coningham, Tasmania. (Mackie et al. 2006) *Invasive Temperate Northern Atlantic [UK] Ireland; British Isles; English Channel (Vieira et al 2014; Bishop et al 2015a; Ferrario et al 2015; Harrower et al 2015; Wood et al 2015) *Introduced; Invasive [Germany] Helgoland; North Sea (Kuhlenkamp and Kind 2013, cited in Porter et al 2015) *Introduced [France] English Channel; Atlantic coast (Bishop et al 2015a; Bishop et al 2015b) *Introduced Helgoland. (Kuhlenkamp and Kind 2013, cited in Porter et al. 2015) *Invasive [W. atterima (Synonymized taxon)] [Western Europe] Though W. s. has not been discovered at La Vigne, on Cap Ferret in the Bay of Archachon for a while after the first record, it was discovered again in the same bay between Archachon and Guian-Mestras, France in 2003. (Ryland et al. 2009) *Alien [W. subovoidea (Synonymized taxon)] [Western Europe] St-Jacut-de-la-Mer, Brittany, France. (Ryland et al. 2009) *Alien [W. subovoidea (Synonymized taxon)] [Western Europe] Chausey and Golfe de Morbihan, Brittany, France. (Ryland et al. 2009) *Alien [W. subtroquata (Synonymized taxon)] [Western Europe] QE II marina just north of St. Peter Port horbour, guernsey, Channel Islands, Brittany, France. (Ryland et al. 2009) *Alien [W. subtroquata (Synonymized taxon)] [Western Europe] Queen Anne's Battery, Plymouth, and Poole Harbour, south coast of England. (Ryland et al. 2009) *Alien Uncertain realm [Australia] (Vieira et al 2014; Bishop et al 2015b) *Introduced

Status Date Non-native:

[US] California: 2012 (Vieira et al 2014) [New Zealand] 2005 (Vieira et al 2014) [UK] First record on English Channel in 2008 (Bishop et al 2015a) [France] First record on English Channel coast of France in 1999; First record on Atlantic coast (Ryland et al 2009 and d'Hondt 1984 and cited in Bishop et al 2015a) [New Zealand] [As Watersipore subtroquta] Victoria Wharf, Dunedin, and Carey's Bay, Port Chalmers: December 1982. (Gordon & Mawatari 1992) [New Zealand] [As Watersipore subtroquta] Port of Wellington, June 1983; Westhaven Marine in Auckland, October 1984; Nelson, April 1985; Napier, September 1986. (Gordon & Mawatari 1992) [Western Europe] [As W. atterima (Synonymized taxon)] La Vigne, on Cap Ferret in the Bay of Archachon: between 1968 and 1973 (first record in France). (Ryland et al. 2009) Between Archachon and Guian-Mestras, France: August 2003. (Ryland et al. 2009) [As W. subovoidea (Synonymized taxon)] St-Jacut-de-la-Mer, Brittany, France: April 1999 (Ryland et al. 2009) [As W. subtroquata (Synonymized taxon)] St-Jacut-de-la-Mer, Brittany, France: April 2005 (Vieira et al. 2014) Guernsey, Brittanhy, France: 2007. (Vieira et al. 2014) [USA] Point Loma Marina, San Diego, California, USA: September 2010. (Vieira et al. 2014)

Vectors and Spread

Initial Vector:

Aquaculture and Fisheries, Hull fouling (commercial, recreational), Natural dispersal

Second Vector:


Vector Details:

[France] Aquaculture with Crassostrea gigas trading (Ferrario et al 2015) [Germany] Natural dispersal on floating seaweeds (Ferrario et al 2015) W. s. was introduced to the Bay of Arcachon with Crassostrea gigas between 1968 and 1973 (d'Hondt 1984, cited in Ryland et al. 2009) W. s. was found on the hull of a pleasure craft. (Ryland et al. 2009) W. s. has spread its distribution to New Zealand, Australia and California in part by shipping, is consistent with a separate introduction to Guernsey as a consequence of maritime traffic. (Ryland et al. 2009) RELATED: Main vector of transport (into Norwegian waters) is highly likely to be leisure craft, as evidenced by the frequent observation of non-native and invasive species in recreational marinas. Some of the doorknocker species may enter Norwegian waters via the aquaculture route (Porter et al 2015)

Spread Rate:

English Channel, opposite sides (Devon and Cornwall - Brittany) within 3 years (2010-2013) (Bishop et al 2015a) Rapid spread; from 2009/10 to 2013/14 collection, has spread from 4 to 19 of visited sites; range in UK spread westward from Plymouth to West Cornwall and eastwards from Gosport to Sussex (Wood et al 2015) RELATED: Likely to spread further north (from Helgoland, Germany) (Porter et al 2015)

Date First Observed in Japan:

Japan: 1882 (Vieira et al 2014)

Date First Observed on West coast North America:

US (California): 2012 (Vieira et al 2014)


Impact in Japan:


Global Impact:

[Economic] Watersipora spp.'s hard encrusting colonies are tolerant of moving water, and their colonies also provide non-toxic points of attachment for other organisms, allowing a diverse fouling community to develop (Floerl et al. 2004, cited in NEMESIS), which can adversely affect the speed and efficiency of ships (NMESIS 2016) [Ecological] In Bodega Harbor, when Watersipora sp. had more than 10% cover on fouling plates, native diversity was correlated with exotic diversity, as both groups of organisms occupied the expanded area (Sellheim et al. 2010, cited in NEMESIS).


Native Temperature Regime:

Mild temperate, Warm temperate, Subtropical, Tropical

Native Temperature Range:

Off Manazuru Peninsula, Sagami Bay: max varied 27ºC-27.5ºC by depth and station in August and min varied 13.9ºC-14.5ºC by depth in March 2001. (Tatara & Kikuchi 2003) Mild temperate, Warm temperate, Subtropical, Tropical (M. Otani, pers. comm.)

Non-native Temperature Regime:

Cool temperate, Mild temperate, Warm temperate, Subtropical, Tropical

Non-native Temperature Range:

San Diego: max 22.0ºC in summer and min 13.0ºC in winter. (Clark et al. 2003) Arcachon Bay: surface water temperature fluctuates annually between 1 and 30 °C. (Deborde et al. 2008) Cool temperate, Mild temperate, Warm temperate, Subtropical, Tropical (M. Otani, pers. comm.)

Native Salinity Regime:

Polyhaline, Euhaline

Native Salinity Range:

Off Manazuru Peninsula, Sagami Bay: max 35.4psu at all depth among two stations in February and min around 25psu at surface in September 2001. (Tatara & Kikuchi 2003)

Non-native Salinity Regime:

Polyhaline, Euhaline

Temperature Regime Survival:

Cool temperate, Mild temperate, Warm temperate, Subtropical

Temperature Range Survival:

[W. subtroquata (Synonymized taxon)] Max: 30.6ºC. Field, based on warmest site in geographical range, Red Sea (Zerebecki and Sorte 2011) [W. subtroquata (Synonymized taxon)] Min: 6.7ºC. Field, based on coldest site in geographical range, Port Townsend WA (Zerebecki and Sorte 2011) Cool temperate, Mild temperate, Warm temperate, Subtropical (M. Otani, pers. comm.)

Temperature Regime Reproduction:


Temperature Range Reproduction:


Salinity Regime Survival:

Polyhaline, Euhaline, Hypersaline

Salinity Range Survival:

Max : 40psu. (NEMESIS 2016) Note: Field salinity of Shark Bay was used in the NEMESIS. However, I did not use the field data of Shark Bay, because W. subtroquata in Shark Bay is presumed not to be W. subatra (See Vieira et al. 2014). Min: 25psu for survival. Field salinity (California) (Cohen 2005, cited in NEMESIS 2016)

Salintiy Regime Reproduction:

Polyhaline, Euhaline

Salinity Range Reproduction:


Depth Regime:

Lower intertidal, Shallow subtidal, Deep subtidal

Depth Range:

[Japan] 15-30m (Vieira et al 2014) Collected from low-tide at Gulf de Morbihan as W. subovoidea (Ryland et al. 2009) and from 50-100 fms as holotype (Vieira et al. 2014). [As W. subovoidea (Synonymized taxon)] Commonest bryozoan species on the lower shore of St-Jcut. (De Blauwe 2005, cited in Ryland et al. 2009)

Non-native Salinity Range:

Native Abundance:



Fertilization Mode:


Reproduction Mode:


Spawning Type:


Development Mode:

Lecithotrophic planktonic larva (non-feeding)

Asexual Reproduction:

Budding/fragmentation (Splitting into unequal parts. Buds may form on the body of the “parent”)

Reproduction Details:

RELATED: [Watersipora] Autozooids are hermaphroditic and brood embryos in embryo sacs (Mawatari 1952, cited in Temkin 1991; Ostrovsky 2013) [Gymnolaemates] Internal fertilization, whether intracoelomic or intraovarian, is obligatory (Temkin 1994 and 1996, cited in Ostrovsky 2013) [Gymnolaemates] Differ from most organisms in that sperm-egg fusion does not stimulate egg activation. Egg activation may not occur until "spawned" outside of maternal zooid (Temkin 1991) [Bryozoans] While sperm is spawned through pores in lophophore tentacles, eggs are usually harbored inside the body wall, and are internally fertilized by sperm, coming in on lophophore feeding currents (Brusca and Brusca 2003, cited in Rouse 2011; Kozloff 1990, cited in Rouse 2011) [Bryozoans] Colonial hermaphrodites, with testes (spermatogenic tissue) and ovaries developing either within the same zooid (zooidal hermaphroditism) or in different zooids within the same colony (zooidal gonochorism) (Ostrovsky 2013) Members of the phylum Bryozoa are hermaphroditic. Both fertilization and egg brooding may either be internal or external (Ruppert et al. 2004) [Bryozoa] All bryozoan colonies are hermaphroditic. Autozooids may be dioecious; or monoecious, and protandrous or protogynous. (Hayward & Ryland 1999) [Bryozoa] Reproduces asexually by budding. (Mawatari 1976)

Adult Mobility:


Adult Mobility Details:

Encrusting (Vieira et al 2014) RELATED: [Bryozoa] The abundance and taxonomic diversity of benthic bryozoan faunas are directly related to substratum. (Hayward & Ryland 1999) [Bryozoa] Bryozoan colonies are sessile (Hayami 1975) [Bryozoa] Bryozoans are a phylum of sessile, colonial suspension feeders found throughout the world in both marine and freshwater environments. (Tilbrook 2012)

Maturity Size:

Zooid: 685-1430 µm x 308-598µm (Vieira et al 2014)

Maturity Age:


Reproduction Lifespan:




Broods per Year:


Reproduction Cues:

RELATED: [Bryozoans] Experiments often used light as a cue to collect embryos/larvae (Woollacott and Zimmer 1977) [Bryozoa] In coastal species light is an important stimulus to larval release, and many cheilostomates shed larvae during the first few hours of daylight. (Hayward & Ryland 1999) [Bryozoa] In various degrees of intensity according to the species temperature also stimulates sexual reproduction. (Winston 1977)

Reproduction Time:

[New Zealand] [As Watersipora subtroquata] More or less year round, with a spring-to-Autumun peak. (Gordon & Mawatari 1992)



Egg Size:

RELATED: [Gymnolaemata] About 200µm (Woollacott and Zimmer 1977)

Egg Duration:


Early Life Growth Rate:

RELATED: [Gymnolaemata] Two phases of larvae metamorphosis: first stage about 20mins; second stage 1-6 days (Woollacott and Zimmer 1977)

Adult Growth Rate:


Population Growth Rate:


Population Variablity:




Coastal shore, Sediment subtidal, Rocky subtidal, Oyster reef, Fouling

Habitat Type:

Epibenthic, Epiphytic, Epizoic, Under rock


Cobble, Rock, Biogenic, Artificial substrate


Semi-exposed, Protected, Very protected

Habitat Expansion:


Habitat Details:

Natural shores; Harbour or marina habitats (Bishop et al 2015b) Aquaculture with Crassostrea gigas trading (Ferrario et al 2015) [W. aterrima (Synonymized taxon)] Found on Crassostrea gigas at Bay of Arcachon. (d'Hondt 1984, cited in Ryland et al. 2009) [W. aterrima (Synonymized taxon)] Found on mid-shore algae Fucus serrtus at LaVigne,on Cap Ferret. (d'Hondt 1984, cited in Ryland et al. 2009) [W. aterrima (Synonymized taxon)] Found on two Crassostrea shells at an oyster farm on a south-shore location between Arcachon and Gujan-Mestras. (Ryland et al. 2009) [W. subovoidea (Synonymized taxon)] It proved to be common on stones and oyster shells on the lower beach at St-Jacut-de-la-Mer. (Ryland et al. 2009) [W. subovoidea (Synonymized taxon)] Found from underside of boulders. (Ryland et al. 2009) [W. subovoidea (Synonymized taxon)] Found on the quay at Chausey. (Ryland et al. 2009) [W. subovoidea (Synonymized taxon)] Found on several low-tidal stones at the eastern side of the entrance to the Golfe de Morbihan. (Ryland et al. 2009) [W. subovoidea (Synonymized taxon)] Found attached to a floating pontoon at St Peter harbour, Guernsey, Channel Islands. (Ryland et al. 2009) [W. subtroquata (Synonymized taxon)] Many colonies of W. s. were on Laminaria fronds but others were on the ascidian Styela clava and on the pontoon itself at St Peter harbour, Guernsey, Channel Islands. (Ryland et al. 2009) Semi-exposed (M. Otani, pers. comm.)

Trophic Level:

Suspension feeder

Trophic Details:

RELATED: [Bryozoans] Suspension feeder...filter phytoplankton less than 0.045mm in size from the water column. (Hill 2001) [Bryozoa] Many phytoplankton species are cleary unsuitable as food for bryozoans. (Hayward & Ryland 1999) [Cheilostomata] Main food is diatom, protozoans and etc. and unappropriate sized particles are ejected (Mawatari 1976)

Forage Mode:


Forage Details:

RELATED: [Bryozoans] Suspension feeder...filter phytoplankton less than 0.045mm in size from the water column. (Hill 2001) [Bryozoa] Many phytoplankton species are cleary unsuitable as food for bryozoans. (Hayward & Ryland 1999) [Cheilostomata] Main food is diatom, protozoans and etc. and unappropriate sized particles are ejected (Mawatari 1976)

Natural Control:

RELATED: PREDATION [Predation] [Bryozoa] Browsers and grazers, including sea urchins, fish, crabs and some prosobranchs, are known to include bryozoans in their diet. (Hayward & Ryland 1998) [Predation] [Bryozoa] Bryozoans are also the prey of very many small, selective predators, some of which may be adapted to a very narrow spectrum of prey species. Among them opisthobranch predators of bryozoans are well known. (Hayward & Ryland 1999) [Predation] [Bryozoa] Other than opisthobranchs as a predator, amphipods, isopods, mites and pycnogonids have all been recorded preying on bryozoan colonies. (Hayward & Ryland 1998) EPIBIONTS [Epibionts] [Cheilostomata] It is frequently observed in Japan that several species of hydroids flourish on Cheilostomata cause damages to them. (Mawatari 1976)

Associated Species:


References and Notes


Bishop, J. D. D., Wood, C. A., Lévêque, L., Yunnie, A. L. E., & Viard, F. (2015a). Repeated rapid assessment surveys reveal contrasting trends in occupancy of marinas by non-indigenous species on opposite sides of the western English Channel. Marine Pollution Bulletin, 95(2), 699-706. Doi: 10.1016/j.marpolbul.2014.11.043 Bishop, J. D. D., Wood, C. A., Yunnie, A. L. E., & Griffiths, C. A. (2015b). Unheralded arrivals: non-native sessile invertebrates in marinas on the English coast. Aquatic Invasions, 10(3), 249-264. Doi: 10.3391/ai.2015.10.3.01 Deborde J, Anschutz P, Auby I, Glé C, Commarieu MV, Maurer D, Lecroart P, Abril G (2008) Role of tidal pumping on nutrient cycling in a temperate lagoon (Arcachon Bay, France). Marine Chemistry 109: 98–114. http://www.epoc.u-bordeaux.fr/indiv/Abril/documents/publi/Deborde_et_al_2008_MAR_CHEM.pdf Ferrario, J., d'Hondt, J. L., Marchini, A., & Occhipinti-Ambrogi, A. (2015). From the Pacific Ocean to the Mediterranean Sea: Watersipora arcuata, a new non-indigenous bryozoan in Europe. Marine Biology Research, 11(9), 909-919. Doi: 10.1080/17451000.2015.1041531 Gordon DP & Mawatari SF (1992) Atlas of marine-fouling Bryozoa of New Zealand ports and harbours. Miscellaneous Publications New Zealand Oceanograhic Institute 107: 1-52. Harrower, C. A., Rorke, S. L., & Roy, H. E. (2015). UK Biodiversity Indicators 2015. Retrieved from DEFRA UK website: jncc.defra.gov.uk Hayami T (1975) Neogene Bryozoa from northern Japan. Science Reports of the Tohoku University, Ser. 2 (Geology) 45: 83-126. http://ci.nii.ac.jp/els/110004646784.pdf?id=ART0007368357&type=pdf&lang=jp&host=cinii&order_no=&ppv_type=0&lang_sw=&no=1458033798&cp Hayward PF & Ryland JS (1999) Cheilostomatous Bryozoa part 2. Hippothooidea - Celleporoidea. Synopses of the British Fauna (New Series). Barnes RSK & Crothers JH (eds.) No. 14 (Second Edition). The Linnean Society of London and The Estuarine and Coastal Sciences Association by Field Studies Council: 416pp. Hill, K. (2001) Smithsonian Marine Station at Fort Pierce. Retrieved from http://www.sms.si.edu/irlspec/Electr_bellul.htm Mackie JA, Keough MJ, Christidis L (2006) Invasion patterns inferred from cytochrome oxidase I sequences in three bryozoans, Bugula neritina, Watersipora subtorquate, and Watersipore arcuata. Marine Bilogy 149: 285-295. Mawatari S (1976) Bryozoa (Ectoprocta). In: Animal systematics. Uchida T (ed.) Nakayama-shoten Co. Ltd., Tokyo: 35-229. (in Japanese) NEMESIS http://invasions.si.edu/nemesis/browseDB/SpeciesSummary.jsp?TSN=156536 Access Date: 15-April-2016. Ostrovsky, A. N. (2013). Evolution of Sexual Reproduction in Marine Invertebrates – Example of gymnolaemate bryozoans. Dordrectht: Springer Netherlands. Doi: 10.1007/978-94-007-7146-8 Porter, J. S., Spencer Jones, M. E., Kuklinski, P., & Rouse, S. (2015). First records of marine invasive non-native Bryozoa in Norwegian coastal waters from Bergen to Trondheim. BioInvasions Records, 4(3), 157-169. Rouse, S. (2011). Aetea anguina. Bryozoa of the British Isles. Retrieved from http://britishbryozoans.myspecies.info/content/aetea-anguina-linnaeus-1758 Ruppert, E.E., Fox, R.S., and Barnes, R.D. (2004). Invertebrate Zoology: A functional evolutionary approach. Ann Arbor, MN: Thomson Brooks/Cole. Ryland JS, De Blauwe H, Lord R, Mackie JA (2009) Recent discoveries of alien Watersipora (Bryozoa) in Western Europe, with redescriptions of species. Zootaxa 2093: 43-59. Tatara E & Kikuchi T (2003) Seasonal change of standing stocks of phytoplankton and some ecological parameters in the coastal waters of Sagami Bay. Actinia 15: 15-24. (in Japanese with English abstract) Temkin, M. H. (1991). Fertilization in the Gymnolaemate Bryozoa (Doctoral dissertation). Retrieved from ProQuest Dissertations and Theses database. (DP23819). Tilbrook KJ (2012) Cheilostomata: first records of two invasive species in Australia and the northerly range extension for a third. Check List 8: 181-183. http://www.checklist.org.br/getpdf?NGD192-11 Vieira, L. M., Jones, M. S., & Taylor, P. D. (2014). The identity of the invasive fouling bryozoan Watersipora subtorquata (d’Orbigny) and some other congeneric species. Zootaxa, 3857(2), 151-182. Doi: 10.11646/zootaxa.3857.2.1 Winston JE (1977). Distribution and ecology of estuarine ectoprocts: A critical review. Chesapeake Science, 18: 34‐57. doi:10.2307/1350363. https://fau.digital.flvc.org/islandora/object/fau%3A6214/datastream/OBJ/view/Distribution_and_ecology_of_estuarine_ectoprocts__A_critical_review.pdf Winston JA & Hemberg BF (1986) Bryozoans from Bali, Lombok, and Komodo. American Museum Novitates 2847: 1-49. Wood, C. A., Bishop, J. D. D., & Yunnie, A. L. E. (2015). RAS 2014 Non-Native Species Rapid Assessment Surveys in English Marinas. Retrieved from the Bromley Trust website: http://www.thebromleytrust.org.uk/files/NNS2014_public.pdf Woollacott, R. M., & Zimmer, R. L. (Eds.). (1977). Biology of Bryozoans. New York, NY: Academic Press Zerebecki R & Sorte CJB (2011) Temperature Tolerance and Stress Proteins as Mechanisms of Invasive Species Success. PLoS ONE 6(4): e14806. http://journals.plos.org/plosone/article/asset?id=10.1371%2Fjournal.pone.0014806.PDF


Limited information; expert opinion based on observational information or circumstantial evidence


Previous examples where species was incorrectly identified as Watersipora subtorquata in collections but uncertain how many instances