Discovery of a New Non-native or Potentially Invasive Worm-Snail from an Artificial Reef of the Florida Keys

Thylacodes vandyensis n. sp.

Artificial reefs are viewed favorably by resource managers who believe they provide habitat structure and settling sites for invertebrate biological diversity, which settle on the site and eventually attract fishes and other organisms.  Artificial reefs produced by purposely creating shipwrecks are popular sites for divers due to the enriched biological diversity of the site.  In addition, it is generally hoped shipwreck sites might take tourist pressure off natural sites. 

Recently, Rüdiger Bieler of the Field Museum of Natural History in Chicago, and his colleagues reported in the journal PeerJ (https://doi.org/10.7717/peerj.3158) that several invasive species of mollusks are settling on shipwrecks including a newly described species of worm-snail presumably from the Pacific Ocean.  Bieler has been studying the natural reefs along the Florida Keys intermittently over the past 30 years and artificial reefs since 2002, so he has a good idea of what is native to the area and what is a new-comer.  Indeed, this recent study follows he and his colleagues’ 2003 discovery of a gryphaeid oyster on the same artificial reefs in the Florida Keys (Bieler et al., 2004).

During dives in 2014 and later in 2016, Bieler observed what looked to be an undescribed species of vermetid worm-snail.  Bieler has studied vermetids off-and-on since 1983 including an examination of relevant museum material, and has collected them at many sites in the Atlantic between Bermuda and Venezuela, so he knows the fauna extremely well.  Although there was a possibility that the species was from the Atlantic and simply had been remained undetected until recently, molecular DNA data indicated the newly described species to be more closely related to Pacific species than to the sampled Atlantic fauna.  The name they gave the species is Thylacodes vandyensis n. sp. Bieler, Rawlings & Collins after the nickname for the wreck USNS General Hoyt S. Vandenberg, where it was found. 

Although some may question why it matters that a new  invasive worm-snail has been discovered in the Florida Keys artificial reefs, the authors note that vermetid-coral interactions are known to be potentially harmful to hard coral growth and survival. Additionally, vermetids have been shown to be intermediate hosts for blood flukes that parasitize loggerhead turtles, so the impacts of this newly invasive species remains to be seen.  

Bieler et al. (2017) attribute their discoveries to “years of focused taxonomic study on the mollusks, access to historical museum collections, and regular resampling within the Florida Keys.”  Continued long-term monitoring is vital to continue to understand the influence of these invasive species on artificial reefs and natural settings and for detection of any other species certain to make an appearance in time.

Literature Cited

Bieler, R., C. Granados-Cifuentes, T. A. Rawlings, P. Sierwald, T. M. Collins.  2017. Non-native molluscan colonizers on deliberately placed shipwrecks in the Florida Keys, with description of a new species of potentially invasive worm-snail (Gastropoda: Vermetidae) PeerJ 5:e3158 https://doi.org/10.7717/peerj.3158

Bieler, R., P. M. Mikkelsen, T. Lee, and D. O. Foighil.  2004.  Discovery of the Indo-Pacific oyster Hyotissa hyotis (Linnaeus, 1758) in the Florida Keys (Bivalvia: Gryphaeidae).  Molluscan Research 24:149-159.