Identification: Plumatella repens is a species of freshwater bryozoan in the class Phylactolaemata. Like other species of bryozoans (also known as Ectoprocta or commonly as moss animals), the individual microscopic aquatic invertebrates (called a zooid) live directly on submerged surfaces in a colony (Ricciardi and Reiswig 1994, Wood 2010, Rubini et al. 2011). Plumatella repens forms tubular colonies that have yellowish or reddish-brown color branches (Bushnell 1965) and has floatoblasts (see the Ecology section for description) that have borders on each side by a single row of large tubercles and an annulus surface that is smooth except for tiny nodules (Thorp and Covich 2010). The colony is mostly open with branching dendritic (treelike) form but, can be dense or fungus-like in appearance (Bushnell 1966). Species in the genus, Plumatella are remarkably difficult to identify (Rubini et al. 2011) and require scanning electron microscope (SEM) identification of the statoblasts (Wood 1996, Thorp and Covich 2010) or use of genetic identification (Rubini et al. 2011).
Native Range: Plumatella repens has a worldwide distribution including documented occurrences in New Zealand, Italy, Scotland, Norway, Sweden, Netherlands, France, Germany, South Africa, Croatia, Spain, Canada, Luxembourg, Austria, United Kingdom, India and United States of America (GBIF 2019). The North American native range is unknown but is considered native to the conterminous US (Bushnell 1965, Thorp and Covich 2010).
Ecology: Plumatella repens is a fast-growing (doubling every 4 to 7 days), but short-lived (persisting no longer than 3 months) bryozoan (Bushnell 1966). Commonly found in tropical or temperate lentic water bodies; lakes, ponds, marshes, streams, and roadside ditches (Bushnell 1966, Thorp and Covich 2010). This species has also been found in a cave in Arizona (Thorp and Covich 2010). Plumatellids are extremely tolerant of various environmental conditions and wide range (5 to 37ºC) of water temperatures (Bushnell 1966). The individual zooids have mucous-coated tentacles that trap diatoms, phytoplankton, and other microscopic organisms, where cilia, or tiny hairs lining the tentacles, sweep the food to the mouth (Wood 2010). The number of tentacles for P. repens ranges from 39 to 65, with an average of 52 (Bushnell 1966). A feeding study with P. repens demonstrated that larger colonies have higher feeding rates than smaller colonies, but this varied with ambient water current (Thorp and Covich 2010).
Plumatella repens can reproduce in several ways. Zooids can clone themselves by budding, but they can also create eggs and sperm and reproduce sexually. Plumatella repens, like other freshwater bryozoans, can also form round hard chitinous buds, statoblasts, which function like seeds. The creation of statoblasts is unique to bryozoans allowing them to endure variable and uncertain conditions of freshwater environments (Ricciardi and Reiswig 1994). A single zooid can produce 15-20 statoblasts (Bushnell 1966). There are two types of statoblasts: floatoblasts (floats in the water column) and sessoblasts (attached to the substrate). Floatoblasts are a practical way to transport P. repens in flowing waters or hitchhiking (Nehring 2002, Green and Figuerola 2005). It is one of the main factors in this species widespread distribution.
Means of Introduction: Plumatella repens can form statoblasts, which under proper conditions, can give rise to a new colony. The floating version of the statoblasts (floatoblasts) can adhere and be moved by migratory water-fowl (Green and Figuerola 2005) and on boats or in ballast tanks (Nehring 2002, Kipp et al. 2010). It is also possible for bryozoans to be introduced by floatoblasts hitchhiking with stocked fishes or aquatic plants (Nehring 2002) or being distribution by floods. Devick (1991) listed introductions in Hawaii as accidental but did not elaborate on the exact means.
Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made. Plumatella species are a known pernicious biofouler and has been found in the industrial intake sites for nuclear power plants (Aprosi 1988), wastewater treatment stations (Wood and March 1999), farm irrigation systems, water treatment facilities (Wood et al. 1998), and other industrial intakes (Gordon and Mawatari 1992). The rapid spread and growth of Plumatella colonies can lead to plugging of the intakes and pipes and clogging of filters (Aprosi 1988, Wood and March 1999).
References: (click for full references)
Aprosi, G. 1988. Bryozoans in the cooling water circuits of a power plant: With 4 figures in the text. Internationale Vereinigung für theoretische und angewandte Limnologie: Verhandlungen 23(3): 1542-1547.
Bushnell, J. H. 1965. On the taxonomy and distribution of freshwater Ectoprocta in Michigan. Part II. Transactions of the American Microscopical Society 84(3): 339-358.
Bushnell, J. H. 1966. Environmental relations of Michigan Ectoprocta, and dynamics of natural populations of Plumatella repens. Ecological Monographs 36(2): 95-123.
Devick, W.S. 1991. Patterns of introductions of aquatic organisms to Hawaiian freshwater habitats. Pages 189-213 in New Directions in Research, Management and Conservation of Hawaiian Freshwater Stream Ecosystem. Proceedings Freshwater Stream Biology and Fisheries Management Symposium. Hawaii Department of Land and Natural Resources.
GBIF. 2019. Global Biodiversity Information Facility (GBIF) Database. Global Biodiversity Information Facility. http://www.gbif.org/. Accessed on 08/13/2019.
Gordon, D. P., and Mawatari, S. F. 1992. Atlas of marine-fouling Bryozoa of New-Zealand ports and harbours. Miscellaneous Publication New Zealand Oceanographic Institute.
Green, A. J., and Figuerola, J. 2005. Recent advances in the study of long-distance dispersal of aquatic invertebrates via birds. Diversity and Distributions 11(2): 149-156.
Kipp, R., Bailey, S. A., MacIsaac, H. J., and Ricciardi, A. 2010. Transoceanic ships as vectors for nonindigenous freshwater bryozoans. Diversity and Distributions 16(1): 77-83.
Nehring, S. 2002. Biological invasions into German waters: an evaluation of the importance of different human-mediated vectors for nonindigenous macrozoobenthic species. Pages 373-383 in Leppäkoski, E., S. Gollasch, and S. Olenin, eds. Invasive aquatic species of Europe: distribution, impacts, and management. Kluwer Adademic Publishers. Dordrecht, The Netherlands.
Ricciardi, A., and H.M. Reiswig. 1994. Taxonomy, distribution, and ecology of the freshwater bryozoans (Ectoprocta) of eastern Canada. Canadian Journal of Zoology 72(2):339-359.
Rubini, A., Pieroni, G., Elia, A. C., Zippilli, L., Paolocci, F., and Taticchi, M. I. 2011. Novel morphological and genetic tools to discriminate species among the family Plumatellidae (Phylactolaemata, Bryozoa). Hydrobiologia 664(1): 81-93.
Thorp, J.H., and A.P. Covich. 2010. Ecology and Classification of North American Freshwater Invertebrates (Third Edition). Academic Press, Elsevier Inc, San Diego, CA.
Wood, T. S., and Marsh, T. G. 1999. Biofouling of wastewater treatment plants by the freshwater bryozoan, Plumatella vaihiriae (Hastings, 1929). Water Research 33(3): 609-614.
Wood, T. S., Wood, L. J., Geimer, G., and Massard, J. 1998. Freshwater bryozoans of New Zealand: a preliminary survey. New Zealand Journal of Marine and Freshwater Research 32(4): 639-648.
Wood, T.S. 2010. Bryozoans. Pages 437-454 in Thorp, J.H., and A.P. Covich, eds. Ecology and classification of North American freshwater invertebrates. Academic Press, London, United Kingdom. London, UK.
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