Australian Tubeworm

Creix en un tub calcari de 30 mm de llarg i que pot arribar a formar colònies molt grans en qualsevol lloc, tant en esculls naturals com en elements flotants artificials; el seu perill radica que pot arribar a obstruir canonades o altres estructures hidràuliques, així com si creix en els bucs dels vaixells. Pot viure en aigües salades i també en salobres, fins i tot en aigües dolces, encara que rarament. És una espècie invasora provinent d'Austràlia, que ja s'ha estès a gran part del món. Fa part de la llista de les 100 espècies invasores més dolentes d'Europa^[1] i del Catálogo español de especies exóticas invasoras.^[2]

S'ha trobat a les aigües de Gandia i del litoral català.

Referències

Ficopomatus enigmaticus, commonly known as the Australian tubeworm,^[1][2] is a species of serpulid tubeworms. Their true native range is unknown,^[3][4] but they probably originated in the Southern Hemisphere,^[1][5] perhaps from the Indian Ocean and the coastal waters of Australia.^[2][6] Today they have a cosmopolitan distribution, having been introduced to shallow waters worldwide.^[3][7] The Australian tubeworm is an invasive species that dominates and alters habitats, reduces water quality, depletes resources, and causes biofouling.^[2]

Taxonomy

Ficopomatus enigmaticus is classified in the genus Ficopomatus in the family Serpulidae.^[1] They are polychaetes belonging to the order Canalipalpata, the bristle-footed or fan-head worms.^[8] The species was first described by the French zoologist Pierre Fauvel in 1923 as Mercierella enigmatica.^[9]

Description

Australian tubeworms are usually about 2 to 2.5 cm (0.79 to 0.98 in) long, and up to 4 cm (1.6 in) at times. On the front end are up to 20 branching gill plumes, which are gray, green, or brown in color. The worms secrete a calcareous tube around themselves, which reaches up to 10 cm (3.9 in) long by 2 cm (0.79 in) wide. The tubes are white and turn brown with age. They are flared at the opening and has flaring rings along their lengths.^[2] The mouth can be sealed with a spiny covering (the operculum).^[6]

Australian tubeworms always live colonially, with many tubes growing together to form small clusters or large reefs.^[3] The aggregations are very dense. There can be up to 180,000 worms per square meter of reef, with the tube openings just about a millimeter apart. The tubes stick together with layers of tiny crystals. The tubes may weave together, and as new worms settle on the outer surface, the reef becomes a solid mass.^[10] Reefs of worms can be over 7 m (23 ft) long.^[2] When the invasion of Lake of Tunis in Tunisia was at its most severe, the total reef mass of the lagoon was thought to contain about 540,000 tons of carbonate.^[11] In shallow water, a reef can be circular in shape as new worms settle along the outer edges. Neighboring reefs may join together to make platforms. In a current, the reef can be elongated.^[11]

Biology

Australian tubeworms are generally found in temperate and subtropical climates. They live in waters up to 3 m (9.8 ft) deep in habitat types such as estuaries and lagoons.^[2] They can tolerate a wide range of salinities, and can be found in marine and hypersaline environments, However, they are most common in brackish water.^[11] They are sensitive to wave action,^[2] and reefs usually grow in protected areas with slow-moving or stagnant water.^[4] The larvae are trochophores that drift with the zooplankton and settle onto the substrate after 20 to 25 days.^[2] They may build their tubes on established reefs or on beds of rock or shells, rocky or woody debris, reefs of other animals such as oysters, beds of vegetation, structures such as docks, piers, and marinas, or objects such as pilings and boats.^[4]

On the coast of South Africa, Australian tubeworms have been observed growing on the aquatic plant Potamogeton pectinatus.^[12] In Argentina, the larvae settle on shells such as those of the sea snail Adelomelon brasiliana and the clams Mactra isabelleana and Tagelus plebeius.^[7] In the Black Sea the reefs are associated with barnacles of the genus Balanus, caridean shrimp of the genus Palaemon, mud crabs of the genus Xantho, amphipods of the genus Orchestia, and isopods of the genus Sphaeroma.^[13] Some tubeworm reefs also have colonies of bryozoans built into them.^[11]

They are filter feeders, gathering zooplankton, phytoplankton, and detritus particles from the water and transporting them to their mouths with the cilia on their gill plumes.^[2][4] During their larval stage, they feed on phytoplankton.^[4] They reproduce sexually, releasing eggs and sperm into the water during spawning. They are iteroparous, able to produce more than one batch of offspring.^[2] They are also protandric hermaphrodites, changing sex from males to females. The older, larger worms in a colony are generally female.^[11] Their lifespan is 4 to 8 years.^[4]

As an invasive species

A colony in a lagoon in Italy

The Australian tubeworm is a fast-growing, aggressive species that acts as an ecosystem engineer, having drastic effects on many aspects of their environment. The worms alter the ecosystem physically, chemically, and biologically.^[2]

The bulky reefs formed by large colonies of Australian tubeworms impede the movement of water, allowing sediment to build up around them.^[2][14] They decrease the aesthetic value of natural lagoons, encrust the hulls of ships, clog the intakes of power plants, pose a hazard to people engaging in water recreation,^[2] and block mechanical structures such as locks.^[4] They are important biofouling organisms, forming heavy crusts on any suitable surface. Unclogging of pipes and cleaning of boats and harbor structures is costly.^[11]

Australian tubeworms easily dominate ecosystems and outcompete native fauna when colonies deplete nutrients with large-scale filter feeding.^[2] They can also survive in polluted and eutrophic, low-oxygen waters that other organisms cannot tolerate as well.^[11] They can provide surfaces for the growth of other introduced species, such as the hydrozoan Cordylophora caspia and the barnacle Balanus improvisus. They can also facilitate the overgrowth of algae.^[4] In sewage-polluted waters they can thrive on the organic particles, creating large colonies that become covered in algae, further decreasing the water quality.^[11] They are known to form colonies on the shells of living animals, such as turtles, molluscs, and crabs.^[11]

Some of the effects of the tubeworm are initially positive. Their efficient filter feeding clears the water of particles, increasing oxygen.^[2] They increase species richness and animal abundance by providing shelter and improved water quality. The microfauna increase. Larger populations of life forms attract detritivores. Reefs are used as resting spots by birds such as swans.^[11] Positive effects of the worm can be outweighed by their dominance of the ecosystem. As they feed, they can deplete resources, and by doing so they have been known to replace native species in the habitat.^[2] They shelter and support other introduced species.^[4] Even when they benefit native species, the outcome can be detrimental. For example, in Argentina the reefs are inhabited by the omnivorous native crab Cyrtograpsus angulatus, which forms dense populations once established. They then prey heavily on many other species. They also increase turbidity and alter the substrate with their burrowing activity.^[14]

Australian tubeworms are introduced to new habitat when they are transported on ship hulls, in ballasts, and on shells.^[6] Management options are mainly limited to the prevention of new introductions. Methods include deoxygenating ballast water to kill larvae and simply scraping the tubes off of ships and other surfaces.^[2]

Gallery

• 

  Individual worm

• 

  Worm and tubes

• 

  A small colony of Australian tubeworms

• 

  Australian tubeworms encrusting a duck decoy

References

Cascail

Ficopomatus enigmaticus, communément appelé Cascail^[2], est une espèce d'annélides polychètes de la famille des Serpulidae. Il s'agit d'une espèce localement envahissante sur les côtes atlantique et méditerranéenne françaises^[2].

Exemple de « pseudo-récif » formé par ce polychète grégaire.

Systématique

L'espèce Ficopomatus enigmaticus a été initialement décrite en 1923 par Pierre FauvelPierre Fauvel (spécialiste des polychètes) sous le protonyme de Mercierella enigmatica^[3]. Cet auteur indique dans son ouvrage de 1923 que cette espèce « forme, sur les tiges de Phragmites, une curieuse association avec un mollusque, Congeria cochleata, un amphipode, Corophium volutator et un bryozoaire, Membranipora lerouxi »^[3].

Description

La longueur de ce ver est d'environ 2,5 cm. Il s'enferme dans un tube calcaire ne dépassant pas les 10 cm et fermé par un opercule en forme de figue.

Il s'agit d'un ver grégaire dont les constructions groupées de tubes forment des « récifs » d'individus pouvant atteindre plusieurs dizaines de centimètres d'épaisseur.

Publication originale

• Pierre Fauvel et Fédération française des Sociétés de sciences naturelles (dir.), Faune de France 5. Polychétes errantes, 1923, 488 p. (lire en ligne)

Notes et références

Ficopomatus enigmaticus, noto in italiano come mercierella, è un anellide polichete marino e di acqua salmastra della famiglia Serpulidae.

Distribuzione e habitat

L'areale di questa specie non è noto con esattezza, si suppone che sia originaria dell'emisfero australe, forse delle coste occidentali australiane^[1] o delle coste orientali dell'America meridionale^[2]. Attualmente è diffuso in gran parte delle coste europee, americane, sudafricane, asiatiche ed australiane. In Europa è presente sia lungo le coste dell'Oceano Atlantico che nel mar Mediterraneo, nel mar Nero e nel mar Caspio. È molto comune lungo i litorali italiani.

Il motivo di una così vasta diffusione come specie aliena è probabilmente da riferirsi al fatto che spesso si insedia sulle chiglie delle navi. In Europa è stata individuata per la prima volta negli anni seguenti alla prima guerra mondiale in acque francesi ed inglesi^[3].

Si tratta di una specie molto eurialina, in grado di sopportare sia acque salmastre quasi dolci che acque ipersaline con salinità molto superiore a quella marina. Vive senza problemi in ambienti con un grado elevato di eutrofizzazione ma evita quelle esposte alle onde o alle correnti preferendo ambienti calmi. Di fatto è molto frequente nelle lagune e nei laghi costieri salmastri e raro altrove.

Descrizione

Si tratta di un polichete tubicolo ovvero che vive all'interno di un tubo calcareo da esso secreto. Si tratta dunque di un organismo sedentario, che passa tutta la sua vita nel punto di insediamento della larva. Questi tubi sono fragili, sottili e lunghi al massimo 5 cm. Il colore è biancastro ma se ricoperto di alghe e detriti può avere tonalità dal verdastro al bruno. I tubi protettivi si rinvengono in aggregati ed ammassi talvolta molto grandi ma fragili e facilmente erodibili. In ambienti idonei possono formare delle biocostruzioni o reef simili a barriere coralline in miniatura, del diametro anche di vari metri^[1].

Riproduzione

Questa specie ha sia individui normalmente sessuati che ermafroditi. La riproduzione avviene nella stagione calda e, nei mari temperato caldi come il Mediterraneo ci possono essere numerosi cicli riproduttivi in una stagione. Nell'Europa settentrionale di solito invece c'è solo una deposizione per stagione.

La larva è planctonica per alcuni mesi quindi si fissa al substrato.

Predatori

Granchi e pesci (nel Mediterraneo soprattutto cefali e ghiozzi) che compiono anche un'importante funzione erosiva sugli aggregati di tubi.

Impatto ambientale

Questa specie fa parte del fouling che ricopre sia le parti immerse delle imbarcazioni che le strutture dei porti. Particolarmente dannoso è quando si insedia nelle prese d'acqua di centrali elettriche o altri impianti dato che può completamente ostruirle in un tempo piuttosto breve.

D'altra parte la presenza di reefs di mercierella in certe lagune salmastre può fungere da vera e propria "oasi" di fondo duro arricchendo la biodiversità^[1].

Galleria d'immagini

Note

Bibliografia

• Giulio Relini (a cura di), Biocostruzioni marine, elementi di architettura naturale, Quaderni habitat n° 22 (2009), Museo friulano di Storia Naturale, Comune di Udine

De trompetkalkkokerworm (Ficopomatus enigmaticus) is een borstelworm uit de familie Serpulidae. Het lichaam van de worm bestaat uit een kop, een cilindrisch, gesegmenteerd lichaam en een staartstukje. De kop bestaat uit een prostomium (gedeelte voor de mondopening) en een peristomium (gedeelte rond de mond) en draagt gepaarde aanhangsels (palpen, antennen en cirri).

Ficopomatus enigmaticus werd in 1923 voor het eerst wetenschappelijk beschreven door Pierre Fauvel.

• ten Hove, H., Fiege, D., Bellan, G. (2011). Ficopomatus enigmaticus (Fauvel, 1923). In: Read, G., Fauchald, K. (Ed) (2011). World Polychaeta database. Gebaseerd op informatie uit het World Register of Marine Species, te vinden op http://www.marinespecies.org/aphia.php?p=taxdetails&id=130988.

カニヤドリカンザシ（学名： Ficopomatus enigmaticus）とは、環形動物門多毛綱ケヤリムシ目カンザシゴカイ科に属する動物の一種。別名「ヤドカリカンザシ」。日本にはもともと分布していない外来種。

分布[編集]

北アメリカ（メキシコ湾岸）、イギリス、オランダ、フランス、ギリシャ、日本沿岸に分布する^[1]。

原産地はよくわかっておらず、ヨーロッパの大西洋岸もしくはインド洋・オーストラリア周辺ともいわれている^[2]。

特徴[編集]

体長10-25mm^[2]。白色もしくは茶色の石灰質の棲管を形成し、貝類や人工物に群体で固着する^[3]。鰓蓋上段の棘は茶褐色または黒色で1列に並ぶ^[3]。鰓糸は約10対^[3]。

塩分耐性をもち、河口域に生息する^[4]。繁殖期は比較的長く、5-8月と8-12月の2つのピークがある^[4]。生まれてから1か月程度で成熟し、寿命は数年とされる^[2]。

外来種問題[編集]

日本では1966年に岡山県児島湾で初めて記録された^[1]。現在では宮城県、千葉県、東京都、神奈川県、静岡県、愛知県、大阪府、岡山県、広島県、島根県、福岡県、石垣島までの広い範囲に定着が拡大している^[1]。各地の湾岸を行き来する船に固着したり、バラスト水に混入したりして導入されたものと考えられる^[2]。

1960年代後半には静岡県の浜名湖で養殖カキに甚大な被害を与えた^[2]。また、在来の近縁種と競争する可能性も指摘されている^[1]。

同様の被害を発生させる近縁種にはカサネカンザシがいる^[2]。

外来生物法により要注意外来生物に指定されている^[2]。有効な対策としては固着した個体を剥ぎ落すことくらいしか手だてはない^[4]。しかし、刺激を与えると放精・放卵してしまうため、水中で駆除を行うと個体数が逆に増える可能性もあり、注意が必要とされる^[4]。

参考文献[編集]

1. ^ ^{a b c d} カニヤドリカンザシ　国立環境研究所 侵入生物DB
2. ^ ^{a b c d e f g} 多紀保彦（監修） 財団法人自然環境研究センター（編著） 『決定版 日本の外来生物』 平凡社、ISBN 978-4-582-54241-7。
3. ^ ^{a b c} 西栄二郎・田中克彦「要注意外来生物としての多毛類カンザシゴカイ類の分類について (PDF) 」 、『神奈川自然誌資料』第27巻、2011年7月9日閲覧。
4. ^ ^{a b c d} 村上興正・鷲谷いづみ（監修） 日本生態学会（編著） 『外来種ハンドブック』 地人書館、ISBN 4-8052-0706-X。