This blog post about Amathia verticillata—AKA the Spaghetti Bryozoan—was written by Avril Lynch, CZM Marine Invasive Species Intern - Summer 2023. Published October 2023.
Species Description and Ecology
Commonly referred to as Spaghetti Bryozoan, or Sauerkraut Grass, Amathia verticillata (formerly known as Zoobotryon verticillatum) can appear as bushy colonies up to a yard wide. The common names for this species reference the transparent, slightly yellow appearance of A. verticillata’s branches, which resemble cooked noodles, or even mung bean sprouts. People who have encountered A. verticillata in the wild have noted that its branches feel hard and flexible, like fake plastic aquarium decorations.
This species was first discovered off the Gibraltar Strait in 1807, but recent studies argue that it may have originated in the Caribbean Sea,1 inhabiting coastal habitats such as seagrass meadows, rocky bottoms, and coral reefs. In Massachusetts, it was first recorded in Buzzards Bay in 2011 during marine species monitoring for the Massachusetts Office of Coastal Zone Management (Adrienne Pappal, personal communication, 2023). Since then, A. verticillata has only been recorded in the Bay State at that same location, with on and off appearances through the years.
A. verticillata colonies are made up of individual animals, or zooids, connected to each other with stolons (which are branching, stem-like structures).2 The “buds” in these colonies are erect, meaning they extend vertically into the water from a small encrusting base.3 All the zooids in an A. verticillata colony are connected via pores in the walls of their branches, and stolons can transport nutrients between adjacent zooids. Each zooid feeds itself using structures at the ends of its branches called lophophores. Each lophophore acts as a mouth and uses a set of tentacles to drive floating food particles into the body.
Spaghetti Bryozoans can withstand a wide range of temperature and salinity. In addition, A. verticillata larvae and fragments can attach themselves to almost any kind of natural or artificial surface—including smooth and clean surfaces4 or surfaces exposed to low temperatures and strong currents. The bryozoan thrives in warm waters and can overwinter as reduced colonies in colder months.5
A. verticillata can also regenerate after receiving physical damage. Detached branches and fragments can settle onto new surfaces and propagate themselves, which allows the species to spread asexually over large distances. Floating stolon fragments from A. verticillata can regenerate even after extended periods of dormancy and form new colonies. The bryozoan can also reproduce sexually using embryos brooded within the sheaths of each autozooid’s filter tentacles. The larval period is brief, however, so A. verticillata is more commonly spread when it attaches to the hull of ships or fragments are carried in ballast water.
The Spread of the Spaghetti Bryozoan
Though its origin is still unknown—whether the Caribbean, the Gibraltar Straight, or some other exotic location—this species has been able to invade areas quietly and quickly across the world because of how easily it can adapt to changes and regrow itself. The first observation of A. verticillata in the United States was in 1905 in San Diego Bay,6 and later the East Coast in Florida in 1908.7 Ever since, it has continued to invade the West and East coasts, reaching as far north as Mystic Seaport, Connecticut (James T. Carlton, personal communication, 2013) and New Bedford, Massachusetts (Adrienne Pappal, personal communication, 2023). The first observation of A. verticillata in Hawaii was in 1921,8 and it was later observed in New Zealand in 19609 and Tokyo Bay in 1963.10 After being first recorded in Cadiz, Spain, in 1807, it rapidly spread to other countries bordering the Mediterranean, like Algeria, Italy, and Egypt.11 It is a recent invader to the Indian Ocean12 and the South China sea,13 as well as the Azores,14 Madeira,15 the Canary Islands,16 South Korea,17 and Australia.18 Today, scientists have recorded A. verticillata as invasive or cryptogenic (that is, a species of unknow origin) in most coastal regions across the world.
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No Sign of Spaghetti Bryozoan During the 2023 Rapid Assessment Survey From August 6-12, 2023, the CZM team and a host of scientific experts was out in the field in search of invasive species as part of the 2023 Rapid Assessment Survey (RAS). Traveling from West Penobscot Bay in Maine to Buzzards Bay in Massachusetts, participants visited marinas and docks to record marine species found on docks and pilings. The RAS, which has occurred every 4 to 5 years since 2000, helps CZM track the spread of new invasives, as well as changes in native species ranges. The CZM team kept an eye out for A. verticillata to observe any spread since its last sighting in Buzzards Bay in 2017—but the bryozoan was not found. Low winter water temperatures in New England may have limited the persistence of A. verticillata, which most successfully establishes in water temperatures above 77° Fahrenheit (22° Celcius) and dies back during cold periods.* Ongoing Rapid Assessment Surveys are critical for understanding how the ranges of cryptogenic and invasive species change or expand over time, especially as warming ocean temperatures may make conditions more favorable for species like A. verticillata. For more information, see CZM’s Rapid Assessment Surveys of Marine Invasive Species web page. 
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| *Micael, J., A. Gillon, N. Jardim, P. Rodrigues, and A.C. Costa. 2018. “Sexual reproduction in the invasive bryozoan Amathia verticillata (Ctenostomatida: Vesiculariidae).” Journal of Coastal Conservation, 22 (2): 305-314. |
Impacts
While economic or ecological impacts of A. verticillata have not been recorded in New England due to its limited establishment, its effects in other parts of the world have been significant. A. verticillata grows on a variety of surfaces, including rock, wood, shells, and vegetation like eelgrass and mangroves. Marinas and harbors tend to be A. verticillata hotspots, as the bryozoan invades new areas by clinging onto traveling boats and then populating docks, buoys, and equipment in new ports. As an efficient fouling species, A. verticillata grows on fishing gear,19 boat vessels, and even inside and around pipes.20 It has also been known to clog intakes at power plants in Israel21 and harm commercial pearl oyster beds in South Korea.22
Not only can A. verticillata potentially cause damage to the economy, but it also can impact native species. It can colonize areas of native growth and significantly deplete phytoplankton populations eaten by native filter feeders.23 For example, in San Diego Bay, A. verticillata grows on the blades of eelgrass (Zostera marina)—reducing the ability of these plants to receive sunlight, which causes them to die and leave bare patches in the seagrass canopy.24A. verticillata also provides suitable settlement surfaces for other invasive fouling organisms,25 causing further damage to native species. Because of the significant impacts of A. verticillata and other introduced species to coastal economies and ecosystems around the world, it is important to monitor New England fouling communities to detect and manage potential range expansions into Massachusetts waters.
Management Options and What You Can Do
As a marine species, management options for A. verticillata are limited.26 Though its branches are soft and easy to remove, A. verticillata’s stolons can regrow new branches, and any manually removed branches left in the water can survive and regenerate on new surfaces. Despite these challenges, there are still some actions that can prevent further spread of non-native species in fresh and marine waters, according to Sailors for the Sea, an organization that educates and activates boating communities toward restoring ocean health.
For example, boaters should regularly remove, bag up, and throw away all visible vegetation and debris from any part of their boat or equipment that has been in the water. Boaters should also regularly drain and flush their motor, livewell, bilge, and transom wells with hot water. Boats should be cleaned by spraying with high pressure water at a regulated facility, then rinsed with hot water, and all surfaces should dry for at least five days before entering a different body of water. SCUBA divers and snorkelers should regularly remove visible vegetation and debris from equipment, and regularly wash suits and equipment in hot water before letting them dry completely. Fishers should wash and dry all fishing equipment after each use. Also, it’s important to never release live bait and to always be aware of local live bait collection laws.
While these preventative measures are strongly encouraged in marine waters, they are required in freshwater bodies in the Bay State. The Massachusetts Stop Aquatic Hitchhikers Law states that you must remove any visible plants from your boat, trailer, or gear before leaving a lake, and you must also disinfect your boat, trailer, or gear before going to a new lake.
If you encounter a freshwater invasive species, please report it to your state’s Department of Natural Resources (in Massachusetts, contact the Massachusetts Department of Conservation and Recreation Lakes and Ponds Program) or to the U.S. Fish and Wildlife Service Aquatic Invasive Species Program. For marine species, please connect with the CZM Marine Invasive Species Program.
These simple steps can help stop the spread of all kinds of invasive marine species, not just A. verticillata. For additional details, see Invasive Species Prevention from Sailors for the Sea and CZ-Tip - Learn to Spot, and Deal with, the Aliens in Our Midst from CZM.
Author
Avril Lynch served as a Marine Invasive Species Intern with CZM’s Coastal Habitat and Water Quality Team during the summer of 2023 working on marine invasive species initiatives, including the Marine Invader Monitoring and Information Collaborative (MIMIC) program. Avril is studying Applied Environmental Studies at Tufts University.
References
1 Galil, B.S., and R. Gevili. 2014. “Zoobotryon Verticillatum (Bryozoa: Ctenostomatida: Vesiculariidae), a New Occurrence on the Mediterranean Coast of Israel.” Marine Biodiversity Records 7 (January): e17.
2 Nascimento, B.K., A.E. Migotto, and K.H. Fehlauer-Ale. 2018. “Molecular Data Suggest the Worldwide Introduction of the Bryozoan Amathia Verticillata (Ctenostomata, Vesiculariidae).” Journal of Coastal Conservation Volume, no. 22: 305-14.
3 Micael, J., A. Gillon, N. Jardim, P. Rodrigues, and A.C. Costa. 2018. “Sexual Reproduction in the Invasive Bryozoan Amathia Verticillata (Ctenostomatida: Vesiculariidae).” Journal of Coastal Conservation 22 (2): 305-14.
4 Robinson, N. 2004. “Interactions between the Nudibranch Okenia Zoobotryon and Its Bryozoan Prey Zoobotryon Verticillatum.” Master of Sciences, Orlando, Florida: University of Central Florida.
5 Fortic, A., D. Trkov, B. Mavric, and L. Lipej. 2019. “Assessment of Bryozoan Xenodiversity in the Slovenian Coastal Sea.” Series Historia Naturalis 29: 179-186.
6 Williams, S.L. 2007. “Introduced Species in Seagrass Ecosystems: Status and Concerns.” Journal of Experimental Marine Biology and Ecology 350: 89-110.
7 Osburn, R.C. 1914. “The Bryozoa of the Tortugas Islands, Florida.” Papers from the Tortugas Islands Laboratory of the Carnegie Institution 5: 181-222.
8 Robertson, A. 1905. “Non-incrusting cheilostomatous bryozoa of the west coast of North America.” Univ. Calif. Publ. Zool. 2(5): 235-322.
9 Gordon, D.P., and S.F. Mawatari. 1992. “Atlas of marine-fouling bryozoa of New Zealand ports and harbors.” Miscellaneous Publications of the New Zealand Oceanographic Institute 107: 1-52.
10 Asakura, A. 1992. “Recent introductions of marine benthos into Tokyo Bay (review): Process of invasion into an urban ecosystem with discussion on the factors inducing their successful introduction.” Journal of the Natural History Museum and Institute, Chiba 2(1): 1-14.
11 Marchini, A., J. Ferrario, and D. Minchin. 2015. “Marinas May Act as Hubs for the Spread of the Pseudo-Indigenous Bryozoan Amathia Verticillata (Delle Chiaje, 1822) and Its Associates.” Scientia Marina 79 (3): 355-65.
12 Menon, R., and B. Nair. 1969. “The ectoproctous bryozoans of Indian waters.” Journal of the Marine Biological Association of India 9(2): 430-432.
13 Huang, Z., and Smithsonian Institution, eds. 2001. Marine Species and Their Distribution in China’s Seas. English ed. Malabar, Fla: Krieger Pub. Co.
14 Amat, J.N., and F. Tempera. 2009. “Zoobotryon verticillatum Della Chiaje, 1822 (Bryozoa), a new occurrence in the archipelago of the Azores (North-Eastern Atlantic).” Marine Pollution Bulletin 58: 761-764.
15 Wirtz, P., and J. Canning-Clode. 2009. “The invasive bryozoan Zoobotryon verticillatum has arrived at Madeira Island.” Aquatic Invasions 4(4): 669-670.
16 Minchin, D. 2012. “Rapid assessment of the bryozoan, Zoobotryon verticillatum (Delle Chiaje, 1822) in marinas, Canary Islands.” Marine Pollution Bulletin 64: 2146-2150.
17 Je, J.G., J.S. Hong, and S.K. Yi. 1988. “A Study on the Fouling Organisms in the Pearl Oyster Culture Grounds in the Southern Coast of Korea.” Ocean Res (Seoul) 10: 85-105.
18 Keough, M.J., and J. Ross. 1999. “Introduced fouling species in Port Phillip Bay.” In: Hewitt, C.L., M.L. Campbell, R.E. Thresher, and R.B. Martin (Eds.) Marine Biological Invasions of Port Phillip Bay, Victoria. Hobart, Tasmania. Pp. 193-225.
19 Gossett, L., J. Lester, and L. Gonzalez. 2004. “Galveston Bay Invasive Species Risk Assessment Final Report.” University of Houston: Environmental Institute of Houston.
20 Ryland, J.S. 1965. “Catalogue of Main Fouling Organisms (Found on Ships Coming into European Waters), Volume 2: Polyzoa.” OECD.
21 Gitay, A., and A. Glazer. 1979. “Biological Fouling in Israel Power Stations and in a Proposed Inter-Sea Conduit.” Israel J Zool 28 (1): 61.
22 Je, J.G., J.S. Hong, and S.K. Yi. 1988. “A Study on the Fouling Organisms in the Pearl Oyster Culture Grounds in the Southern Coast of Korea.” Ocean Res (Seoul) 10: 85-105.
23 Amat, J.N., and F. Tempera. 2009. “Zoobotryon Verticillatum Delle Chiaje, 1822 (Bryozoa), a New Occurrence in the Archipelago of the Azores (North-Eastern Atlantic).” Marine Pollution Bulletin 58 (5): 761-64.
24 Williams, S.L. 2007. “Introduced Species in Seagrass Ecosystems: Status and Concerns.” Journal of Experimental Marine Biology and Ecology 350: 89-110.
25 Marchini, A., J. Ferrario, and D. Minchin. 2015. “Marinas May Act as Hubs for the Spread of the Pseudo-Indigenous Bryozoan Amathia Verticillata (Delle Chiaje, 1822) and Its Associates.” Scientia Marina 79 (3): 355-65.
26 Pappal, A. 2010. “Marine Invasive Species: State of the Gulf of Maine.” Boston, MA: Gulf of Maine Council on the Marine Environment and the Massachusetts Office of Coastal Zone Management.