Short description of Tricellaria inopinata, Tufty-buff bryozoan

Flexible, pale brown or pinkish-brown, erect colonies up to about 4 cm high, consisting of densely bifurcating double rows of very small (0.5-0.6 mm) individuals; colony attached at base by root-like rhizoids.

Impact summary: Tricellaria inopinata, Tufty-buff bryozoan

Populations in harbours and marinas can become very dense, with almost all submerged surfaces bearing a pale brown ‘fuzz’ of T. inopinata. Could potentially presumably affect the abundance and habitat occupancy of other shallow-water suspension feeding sessile invertebrates.  However, it is not clear whether this would cause the local extinction of any species.  Will rapidly colonise hulls of leisure craft (unpublished data), and is thus a prime agent of nuisance fouling. Negative impacts on aquaculture not reported, although possible.

Habitat summary: Tricellaria inopinata, Tufty-buff bryozoan

Attached to solid surfaces in shallow water, especially in harbours and marinas: pontoon floats, wave screens, buoys, hulls, kelps and other sessile invertebrates. Also found on natural shores, often on algae.

Overview table

Environment	Marine
Species status	Non-Native
Native range	Pacific
Functional type	Filter-feeder
Status in England	Non-Native
Status in Scotland	Non-Native
Status in Wales	Non-Native
Location of first record	Poole Harbour
Date of first record	1998

Origin

Tricellaria inopinata was described as new to science from the Lagoon of Venice, but recognised as likely to be non-native in that locality. The native range is undetermined, but almost certainly Pacific, with the west coast of North America a strong candidate region.  This species appears morphologically near-identical to, and thus potentially conspecific with, the entity from the west coast of North America south of Point Concepcion originally described as Menipea occidentalis catalinensis subsp. nov. by Robertson (1905). If this form is indeed conspecific with T. inopinata, Robertson’s name has priority, but the name Tricellaria catalinensis has not so far been adopted for the introduced species in Europe.

First Record

In GB, first detected in Poole Harbour in 1998, and found to be present on the English Channel coast from Swanage to Chichester Harbour in 1999.

Pathway and Method

Introduction by hull fouling likely, and suggested by association with marinas and ports, but transport with commercial oysters also possible.

Species Status

Currently known from marinas and harbours from the Clyde around the south coast of England and up the east coast as far as Grimsby. Also found on natural GB shores, at least on the south coast. Also present as an introduced species in the Netherlands and Belgium, and on Atlantic coasts of France and Spain.  Globally, also introduced in Australia and New Zealand, but not yet reported from east coast of North America.

Dispersal Mechanisms

Adult phase sessile and larva non-feeding (hence presumably relatively brief motile phase).  A common fouling species, and dispersal on hulls of both leisure and commercial craft very probable, with commercial movements of bivalves also a possible vector.

Reproduction

Hermaphroditic (and thus potentially self-fertilizing, but cross-fertilization known in other bryozoans with similar basic reproductive biology), brooding embryos internally.  Larva non-feeding, thus likely to settle within a few hours to metamorphose into founding zooid (ancestrula) of new colony. In a Plymouth marina, larvae were brooded in all months except February and March, with high levels of brooding between June and October.

Known Predators/Herbivores

Natural predators not known, but similar species grazed by nudibranchs, pycnogonids, etc.

Resistant Stages

No resistant or resting stage in life cycle.  Some growth continues year-round in colonies in a Devon marina.

Habitat Occupied in GB

Attached to solid surfaces in shallow water, especially in harbours and marinas: pontoon floats, wave screens, buoys, hulls, kelps and other sessile invertebrates. Also found on natural shores, often on algae.

Currently known from marinas and harbours from the Clyde around the south coast of England and up the east coast as far as Grimsby. Also found on natural GB shores, at least on the south coast. Also present as an introduced species in the Netherlands and Belgium and on Atlantic coasts of France and Spain.  Globally, also introduced in Australia and New Zealand, but not yet reported from east coast of North America.

Environmental Impact

Populations in harbours and marinas can become very dense, with almost all submerged surfaces bearing a pale brown ‘fuzz’ of T. inopinata.  Will thus presumably affect the abundance and habitat occupancy of other shallow-water suspension feeding sessile invertebrates.  However, it is not clear whether this would cause the local extinction of any species.  Also, kelps can become heavily fouled, particularly in sheltered sites, presumably increasing drag.

Health and Social Impact

None known.

Economic Impact

Will rapidly colonise hulls of leisure craft, and is thus a prime agent of nuisance hull fouling. Negative impacts on aquaculture possible but none reported; its relatively nondescript appearance may make attribution of impact to this species less likely.

Identification

d'Hondt, J.-L. & Occhipinti  Ambrogi. A. (1985) Tricellaria inopinata, n. sp., un nouveau Bryozoaire Cheilostome de la faune méditerranéenne. P.S.Z.N.I.: Marine Ecology, 6, 35-46.

Robertson, A. (1905) Non-incrusting chilostomatous Bryozoa of the west coast of North America. University of California Publications in Zoology, 2, 235-322.

Biology, ecology, spread, vectors

Dyrynda, P.E.J., Fairall, V.R., Ambrogi, A.O. & d'Hondt, J.L. (2000) The distribution, origins and taxonomy of Tricellaria inopinata d'Hondt and Occhipinti Ambrogi, 1985, an invasive bryozoan new to the Atlantic. Journal of Natural History, 34, 1993-2006.

De Blauwe, H. & Faasse, M.A. (2001) Extension of the range of the bryozoans Tricellaria inopinata and Bugula simplex in the North-East Atlantic Ocean (Bryozoa: Cheilostomatida). Nederlandse Faunistische Mededelingen, 14, 103-112.

Management and impact

General

Arenas, F., Bishop, J. D. D., Carlton, J. T., Dyrynda, P. J., Farnham, W. F., Gonzalez, D. J., Jacobs, M. W., Lambert, C., Lambert , G., Nielsen, S. E., Pederson, J. A., Porter, J. S., Ward, S. & Wood, C. A. (2006) Alien species and other notable records from a rapid assessment survey of marinas on the south coast of England. Journal of the Marine Biological Association of the United Kingdom, 86, 1329-1337. doi:10.1017/S0025315406014354

d'Hondt, J.-L. & Occhipinti  Ambrogi. A. (1985) Tricellaria inopinata, n. sp., un nouveau Bryozoaire Cheilostome de la faune méditerranéenne. P.S.Z.N.I.: Marine Ecology, 6, 35-46.

https://www.cabi.org/isc/datasheet/109093