Biological Invasions

, Volume 18, Issue 6, pp 1737–1744 | Cite as

Cryptic invaders: nonindigenous and cryptogenic freshwater Bryozoa and Entoprocta in the St. Lawrence River

  • Kayla M. Hamelin
  • Rowshyra A. Castañeda
  • Anthony RicciardiEmail author
Original Paper


The distributions of most cosmopolitan invertebrate species are assumed to result from natural processes. Cryptic invertebrates with obscure biogeographic origins are often considered native by default, resulting in potentially severe underestimation of the extent of human-assisted invasions. This problem is exemplified by freshwater Bryozoa (Ectoprocta) and Entoprocta—small and widely distributed invertebrates commonly found in lakes and rivers. A benthic survey of a thermally modified section of the St. Lawrence River revealed the presence of two nonindigenous bryozoans: Carter’s moss animal Lophopodella carteri (Hyatt) and the crystal moss animal Lophopus crystallinus Pallas. Also discovered was a cryptogenic entoproct, the goblet worm Urnatella gracilis Leidy. These species were collected as statoblasts and (in the case of U. gracilis) colonial fragments downstream of the Gentilly-2 nuclear power plant at Bécancoeur, Quebec. Local densities of both U. gracilis and L. carteri increased by an order of magnitude at sites closer to the power plant. The occurrence of Lophopus crystallinus statoblasts in St. Lawrence River sediments is the first documented physical evidence of the species in North America. Contrary to the presumed natural Holarctic distribution of L. crystallinus, our literature review found that published historical records of L. crystallinus in the United States are erroneous or unsubstantiated. We propose that L. crystallinus is a western Palearctic species recently introduced to the St. Lawrence River, most likely as statoblasts discharged with ballast water from transoceanic ships.


Biogeography Bryozoa Ectoprocta Entoprocta Kamptozoa Lophopus crystallinus Lophopodella carteri Urnatella gracili



We thank three anonymous reviewers for their comments, and Prof. Timothy S. Wood (Wright State University) for providing information on reports of L. crystallinus. We also acknowledge the following people for their assistance in the lab and in the field: Kara Lynn Beckman, Marie-Claire Chiasson, Emilija Cvetanovska, Natasha Dudek, Charlotte Lapeyre, Andrea Morden, Ian Perrera, Dustin Raab, Katherine Shaw, Isabel Tom, Karen Wang, and Yinci Yan. Funding by an NSERC Julie Payette Scholarship to K.H. and an NSERC Discovery Grant to A.R. is gratefully acknowledged.

Supplementary material

10530_2016_1116_MOESM1_ESM.docx (35 kb)
Supplementary material 1 (DOCX 35 kb)


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Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  • Kayla M. Hamelin
    • 1
  • Rowshyra A. Castañeda
    • 1
    • 2
  • Anthony Ricciardi
    • 1
    Email author
  1. 1.Redpath MuseumMcGill UniversityMontrealCanada
  2. 2.Department of Ecology and Evolutionary BiologyUniversity of Toronto- ScarboroughTorontoCanada

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