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Waterzakmosdiertje Pectinatella magnifica


Pectinatella [genus] (1/0)
magnifica [soort]

Exotenpaspoort ?

Vestigingsstatus Gevestigd
Zeldzaamheid Lokaal
Invasiviteit Potentieel invasief
Invasiviteit (toelichting) P. magnifica is a bryozoan from fresh water. Instead of forming encrusting colonies on solid substrata, as most marine bryozoa do in the Netherlands, it forms large soft, gelatinous translucent colonies with many star-like blooms. As they usually bind together, sometimes extremely large round objects are formed, shaped like a baseball (up to 30 cm or more). The colonies are found in lakes, rivers, ponds and other waters, attached to various substrata (rocks, wood, aquatic vegetation, sponges, unionids and other bryozoans). The clumps may also float, seemingly unattached to anything. This species is native to Eastern North America and introduced in the Western parts of the United States. It is also introduced to Europe (at least around 1883) and is recorded from (a.o.) France, Germany, the Netherlands, Luxembourg, Austria and the Czech Republic. Recently it has also been introduced to Asia, to Japan and Korea (Seo 1998). Its invasiveness is shown by the broad dispersal outside its native range, its broad temperature range (cold temperate-warm temperate), its adaptibility to different environments (tidal to nontidal freshwater, marshes, lakes, canals, ponds) and its reproduction and survival strategy (the zooids are hermaphroditic, colonies also produce asexual propagules: statoblasts enclosed by a chitinous shell). Colonies die off in winter, but the statoblasts remain dormant and are resistant to desiccation and freezing. This enlarges the potential for dispersal (Fofonoff et al,. 2003). The species is distributed by shipping, fish introductions, and possibly also trade in ornamental water plants (Nehring 2002, 2006).
Type introductie Niet opzettelijk
Jaar van eerste introductie 2004
Jaar van eerste melding 2005
Natuurlijke verspreiding Noord-Amerika
Verspreiding in Nederland
  • Drenthe
  • Gelderland
  • Groningen
  • Limburg
  • Noord-Brabant
  • Overijssel
  • Verspreiding in Nederland (toelichting) In 2004 statoblasts of P. magnifica were found for the first time in the Netherlands in the Hunze River (or Oostermoersevaart) which runs through the provinces of Drenthe and Groningen and flows into the Zuidlaardermeer. Subsequently recordings from other provinces followed (prov. Gelderland: Arnhem; prov. Overijssel: Zwartsluis; prov. Noord Brabant: Tilburg; prov. Limburg: Roermond). The species has only been found at a few localities but has already has spread over six different provinces suggesting a wider distribution than currently known.
  • Meren
  • Waterwegen
  • Wetlands
  • Wijze van introductie
  • Visserij
  • Huisdier-/aquariumhandel
  • Hengelsport-/visuitrusting
  • Ballastwater schip/boot
  • Aangroei op scheepsrompen
  • Ecologische impact (toelichting) Large freshwater organisms like Pectinatella magnifica, sometimes become very abundant. If growing on plants and other surfaces, they may overgrow other freshwater organisms. Some degree of competition for space and resources may also be possible, but this is never mentioned from European waters. From the Netherlands there are no indications of an ecological impact. The species is eaten by fishes, crayfish and some insects, like for instance caddisflies.
    Economische impact (toelichting) Large clumps of this bryozoan may clog fishing nets or even foul power plant water systems and obstruct municipal water systems (Ricciardi and Reiswig 1994). From its introduced range there are no reported impacts of P. magnifica in general (Fofonoff et al. 2014).


    • Fofonoff, P.W., G.M. Ruiz, B. Steves & J.T. Carlton 2003. National Exotic Marine and Estuarine Species Information System. [link]
    • Nehring, S. 2002. Biological invasions into German waters: An evaluation of the importance of different human-mediated vectors for nonindigenous macrobenthic species. 373-383. Kluwer Academic Publishers, Dordrecht, Boston, London.
    • Nehring, S. 2006. Four arguments why so many alien species settle into estuaries, with special reference to the German river Elbe. Helgoland Marine Research 60: 127-134.
    • Ricciardi, A. & H.M. Reiswig 1994. Taxonomy, distribution, and ecology of the freshwater bryozoans (Ectoprocta) of eastern Canada. Canadian Journal of Zoology 72: 339-359.
    • Seo, J.E. 1998. Taxonomy of the marine bryozoans from Namheado Island and its adjacent waters, Korea. Korean journal of systematic zoology 14: 415-424.