Bugula neritina

Invasion History

General Invasion History:

Bugula neritina was described by Linnaeus from Europe in 1758, from the Mediterranean Sea. The Bugula 'neritina', widely identified in fouling communities is a widespread species complex of unknown tropical-warm-temperate origin, now widespread and cryptogenic in equatorial regions. It has been introduced to higher-latitude and more isolated ocean regions including the coast of northern Europe (Ryland 1960), the southwest Atlantic (Marcus 1937; Orensanz et al. 2002), the northeast Pacific (Carlton 1979; Wonham and Carlton 2005), Hawai'i (Carlton and Eldredge 2009), and the southwest Pacific (Keough and Ross 1999; Cranfield et al. 1998). In the English Channel and Long Island Sound, it appeared first near thermal effluents and gradually spread to other habitats (Ryland 1960; Carlton, personal communication 2004; Ryland 2011). In both the northeast Pacific and northwest Atlantic, B. 'neritina' has been extending its range northward, reaching Coos Bay, Oregon by 1986 (Wonham and Carlton 2005, and the Gulf of Maine (Boston and Salem Harbors, Massachusetts), by 2000 (MIT Sea Grant 2004). 
 
Many shallow-water populations around the world (England, Hong Kong, Hawaii, Australia, California, North Carolina, Curacao) share a single cytochrome oxidase (COI) haplotype (S1, McGovern and Hellberg 2002; Mackie et al. 2006). In California, a presumably native form 'D' is primarily found in more open marine waters (3-12 m) than the S 'shallow' form (0-8 m). The two forms have differing bryostatins, COI haplotypes, and endosymbionts Mackie et al. 2006; Davidson and Haygood 1999). 

North American Invasion History:

Invasion History on the West Coast:

Robertson (1905, cited by Cohen and Carlton 1995) and Osburn (1940) reported that Bugula 'neritina' was widespread in southern California, ranging up to Monterey Bay. At least two cryptic species are present on the West Coast, the cosmopolitan Type S (shallow, 0-8 m) and the presumed native Type D form (Davidson and Haygood 1999). We assume that most or all West Coast harbor populations of B. 'neritina' are type S, based on molecular identifications from Scripps Pier, Newport Bay, Catalina Harbor, Santa Cruz Harbor, San Francisco Bay and Humboldt Bay (Davidson and Haygood 1999; Mackie 1999). In recent surveys, B. 'neritina', assumed to be the S form, has been reported from every California bay sampled, from San Diego Bay to Humboldt Bay (Cohen and Carlton 1995; Wasson et al. 2001; Cohen et al. 2002; Fairey et al. 2002; de Rivera et al. 2005; Needles 2007). Some overlap between the S and D forms may occur, since both types were found at similar depths on the open coast at Patrick Point (Humboldt County) and Humboldt Bay (Davidson and Haygood 1999).

There is evidence of a northward shift in the range of the harbor form of B. 'neritina'. It was first collected in San Francisco Bay probably in the early 1980s (Kozloff 1983, cited by Cohen and Carlton 1995), in Humboldt Bay in 1987 (Carlton and Hodder 1995), and Coos Bay, Oregon in 1986 (Cohen and Carlton 1995; Wonham and Carlton 2005). Cohen and Carlton (1995) note a record from about 1994 in Friday Harbor, Washington. 

Invasion History on the East Coast:

On the Atlantic Coast of North America, Bugula 'neritina' was identified by A. E. Verrill and reported by Coues and Yarrow (1878) from Fort Macon, near Beaufort, North Carolina. It was collected from the Dry Tortugas, Florida (Caribbean-Gulf of Mexico) by Osburn (1914) and appears to have been widespread in the Atlantic from south of Cape Hatteras, Florida through the Gulf of Mexico, and through the Caribbean Sea by the early-mid 20th century (Osburn 1914, Osburn 1940; Osburn 1947; Shier 1964; Maturo 1957; Winston 1977). We regard this bryozoan as cryptogenic within its distribution south of Cape Hatteras and in the Caribbean and Gulf of Mexico.

Bugula 'neritina' was collected in the 19th century in Massachusetts waters (Nahant, 1854; Provincetown, 1876) (Winston and Hayward 2012), but apparently was not established north of Cape Hatteras until the late 20th century. It was not found in early surveys at the mouth of the Chesapeake Bay (1915–1922), or in adjacent Atlantic coastal bays by Osburn (1932, 1944), but was first collected in 1985 in fouling within thermal effluents at Millstone Nuclear Power Plant, in Waterford, Connecticut, Long Island Sound (Carlton, personal communication, 1999). Subsequently, this bryozoan became widespread at Avery Point, Groton, Connecticut, and other Long Island Sound locations away from thermal effluents (Osman, personal communication 2004). In 2000 and 2001, it was collected on settling plates at Kiptopeke, Virginia, at the mouth of the Chesapeake Bay (Ruiz et al., unpublished data). By 2003, B. 'neritina' was found at various harbor locations from Chesapeake Bay to Casco Bay, Maine (McGovern and Hellberg 2003; MIT Sea Grant 2003; Ruiz et al., unpublished data).

Molecular studies of Bugula 'neritina', and studies of its bacterial endosymbionts indicate that at least two genotypes occur in the Northwest Atlantic. The cosmopolitan type 'S' is found from Cape Hatteras to the Gulf of Mexico and the Caribbean (McGovern and Hellberg 2003; Mackie et al. 2006), and a North Atlantic lineage identified by specimens from Delaware, Connecticut, and Massachusetts (McGovern and Hellberg 2003). While the North Atlantic lineage of Bugula 'neritina' appears to be genetically distinct from the widely introduced type S, the history of B. 'neritina', north of Cape Hatteras strongly suggests a recent introduction. However, the origin of this genotype is unknown. We predict that when more populations are studied, a source population of the North Atlantic lineage will be found in another part of the world. The Northwest Atlantic genotype 'N',  has been found in California and Queensland, Australia (Fehlman-Ale et al. 2014), but its origin is unclear.

Invasion History in Hawaii:

Bugula 'neritina' was first collected in Pearl Harbor, Oahu, in 1921. It is now found throughout the main Hawaiian Islands, including harbors in Maui and Kaua'i (Coles et al. 1999; Coles et al. 2004; Carlton and Eldredge 2009). Mackie et al. (2006) identified specimens from Pearl Harbor as belonging to haplotype S, the cosmopolitan form. One specimen was found on fouling plates in Bar Harbor, Ketchikan (Jurgens et al. 2018).

Invasion History Elsewhere in the World:

Bugula neritina was described from the Mediterranean, where we consider it cryptogenic. It was first reported in Atlantic Europe in 1959, in a heated dock in Swansea, Wales (Ryland 1960). It apparently disappeared from British waters in the 1960s, possibly because of severe winters or cool summers, but reappeared or was rediscovered by 2004 in several locations on the south coast of England (Arenas et al. 2006). By 2011 it was widespread on Britain's south coast and present further north in the Irish Sea, to Wales, Scotland, and Ireland (Ryland et al. 2011). Elsewhere in Europe, it was found in Costa Lugo, Spain, on the Bay of Biscay (1997, Cesar-Aderiz et al. 1997), and subsequently found in many locations from the Netherlands to Cadiz, Spain (Ryland et al. 2011). Bugula neritina has also been found in the Azores (Ryland et al. 2011) 
 
In the southwest Atlantic, B. neritina was reported from Santos, near Sao Paulo by 1937 (Marcus 1937). On the subtropical-temperate Atlantic Coast of South America, B. neritina is reported from lha Grande Bay in Rio de Janeiro State, Brazil to Cabo Blanco, Argentina (47 S) and Port William in the Falkland Islands (52 S) (Gappa 2000; Orensanz et al. 2002; Vieira et al. 2008; Ignacio et al. 2010). In the mid-South Atlantic, it has been found on the remote island of Tristan da Cunha (37 S) (Ryland et al. 2011). On the west coast of South America, it was widespread in Chile in 1982, ranging from Arica (18 S) to Aruaco (37 S) (Moyano 1982, cited by Castilla et al. 2005). Bugula ‘neritina’ is considered an introduction to the Galapagos Islands, where it may have been first found in 1924 (Banta 1991, cited by Carlton 2019; McCann et al. 2019). 
 
Bugula neritina has been introduced to Pacific Island harbors, including those in American Samoa (Coles et al. 2002) and Palau (Marnie Campbell and Chad Hewitt 2009, personal observations). It was introduced to Port Philip Bay, Victoria, Australia by 1881 (Keough and Ross 1999) and is now widespread in harbors on the Australian coast (Brock 1983; Keough and Ross 1999; Wyatt et al. 2005; Mackie et al. 2006). In New Zealand, the first definite collection was at Wellington on the Cook Straits (1949, Ralph and Hurley 1952, cited by Gordon and Matawari 1992), but it is now widespread in New Zealand ports (Gordon and Matawari 1992).

Description

Colonies of Bugula neritina form bushy tufts 100 mm or more in height. The tips of the branches show slight spiral growth, and the bases consist of two parallel series of zooids (bifurcation type 4 of Ryland 1960, Hayward and Ryland 1998). The zooecia (zooids) are large, 600–800 µm, narrowing proximally. Spines are absent, but the distal margin forms an angular projection. This bryozoan has no avicularia. The polyps have 23–24 tentacles. The ooecia are attached to inner distal angles of the zooids, obliquely to the angle of the branch, and resemble 'miniature snail shells' (Hayward and Ryland 1998), and 'seem to form a series of small beads along the branches' (Osburn 1950). Colony color is 'purplish brown', or 'dark reddish purple' and translucent brown when preserved. The developing embryos are brown, and reach ~250 µm in diameter. The ancestrula is symmetrical, with a pedestal-like base, and lacks spines or rootlets. This description is based on information from Osburn (1940), Maturo (1957), Ryland (1960), Gordon and Mawatari (1992), Hayward and Ryland (1998) and Winston and Hayward (2012).

Bugula neritina constitutes a widespread species complex of forms which can only be distinguished by molecular methods. At least three cryptic species are present, designated as 'Type S' (shallow-water, cosmopolitan), ‘Type D’ (open water, California, presumed native), and a ‘North Atlantic lineage’ (Connecticut and Delaware) (Davidson and Haygood 1999; McGovern and Hellberg 2003; Mackie et al. 2006). A recent analysis (Fehlman-Ale et al. 2014) supports this general picture, but found haplotype N, the 'Northwest Atlantic genotype' occurring in Queensland, Australia, and central California).

Taxonomy

Ecology

General:

Life History- Bugula neritina is a bush-like, calcified bryozoan, composed of many individual zooids. The zooids feed by extending the ciliated tentacles of the lophophore as a funnel, creating a current, and driving food particles into their mouths. The food is guided along the tentacles and through the pharynx by the cilia. Larger food particles can be moved or captured by flicking or contracting the tentacles. The zooids are hermaphroditic and produce large yolky eggs that hatch into lecithotrophic larvae, which are planktonic for short periods (less than 1 day). Larvae settle on a substrate and metamorphose into the first zooid of a colony, an ancestrula (Barnes 1983).

Ecology- Bugula neritina attaches to stones, wood, pilings, floats, buoys, ship hulls, seaweed, seagrasses, oysters, other bryozoans, and other hard substrates (Ryland 1965; Gordon and Mawatari 1992; Hayward and Ryland 1998; Ryland et al. 2011).

Food:

Phytoplankton, detritus

Trophic Status:

Suspension Feeder

Habitats

Life History

Tolerances and Life History Parameters

General Impacts

Economic Impacts 

Shipping, Industry- Bugula 'neritina' is a frequent fouling organism and has been found on fixed structures, ship hulls, in ships' internal water systems, and in power plants using seawater in warm waters worldwide (Ryland 1971). Bugula 'neritina' collected in Botany Bay, Australia, proved highly resistant as larvae and adults to dissolved copper, an active agent in many antifouling paints, and therefore have the potential to foul coated hulls (Piola and Johnston 2006).

Fisheries- Bugula 'neritina' has fouled aquaculture nets and cages (Hodson et al. 1997). This bryozoan also contributed to fouling which slowed the growth of cultured mussels (Perna perna) in Brazil (de Sá et al. 2007).

Human Health- Bugula 'neritina' has a positive economic impact, as a source of bryostatins, potential anticancer compounds (Davidson and Haygood 1999). The extracted, purified compounds can be worth $380,000 per pound (Lovell et al. 2008).

Ecological Impacts 

Competition- Bugula 'neritina' in subtropical-tropical waters worldwide is a major competitor in the fouling community (Sutherland and Karlson 1977; Winston 1982). The tolerance of Bugula 'neritina' to copper-based antifouling paints (Piola and Johnston 2006) may give it a competitive advantage over more sensitive species, such as Schizoporella errata and Tricellaria occidentalis (Piola and Johnston 2006). Bugula neritina was one of several invasive fouling species which showed increased growth (zooid number) at temperatures 3.5 and 4.5 °C above the ambient temperature in Bodega Harbor (13.5 °C), while the native colonial tunicate Distaplia occidentalis showed reduced survival (Sorte et al. 2010). Bugula 'neritina' was one of a group of seven non-native species in Bodega Harbor, most of which were rare or absent in 1970–1971, but were among the eight most abundant species in 2006. Spawning periods and the abundance of species in this group appeared to be favored by a 1 °C increase in average temperatures at this site over a 30-year period (Sorte and Stachowicz 2011).

Regional Impacts