Neodexiospira brasiliensis

Invasion History

General Invasion History:

Neodexiospira brasiliensis was described from Florianopolis, Brazil, but its native region is uncertain. One early record (as Spirorbis bellulus, Bush 1904) was taken from Suruga Bay, Japan. Knight -Jones and Knight-Jones (1975) note that the genus Neodexiospira has its greatest diversity in the Indo-Pacific, where it ranges from the Kurile Islands to New Zealand (Knight-Jones and Knight-Jones 1975; Rzhavsky 1991). Early introduced records are from Mississippi (1^st record 1942, Hartman 1951; Knight-Jones et al. 1975, no further records); South Africa (1^st record 1953, Knight-Jones and Knight-Jones 1984; Mead et al. 2011b); North Carolina (1^st record 1974, Nelson 1979); England (1^st record 1974, Critchley et al. 1985); and California (Knight-Jones et al. 1979).

North American Invasion History:

Invasion History on the West Coast:

In 1974, Neodexiospira brasiliensis was found on harbor floats at three southern California marinas: Marina del Rey, Alamitos Bay, and San Pedro Harbor (Knight-Jones and Knight-Jones 1975). They noted that the appearance of Neodexiospira spp. is sporadic, which they suggested might be due to red tides. In a 2011 survey, this worm was found on floats and pilings in central California at Tomales and Monterey Bays, as well as 10 southern California bays and harbors from Channel Islands Harbor (Oxnard) to San Diego Bay, including Avalon Harbor, on Santa Catalina Island (California Department of Fish and Game 2014). We have no information as to whether N. brasiliensis has colonized seaweeds or seagrasses, as it has in Japan, Europe, and North Carolina. It may be overlooked due to similarity with native spirorbids.

Invasion History on the East Coast:

In 1974, Neodexiospira brasiliensis was first reported from the Newport River, Morehead City, North Carolina. Abundant populations were found settling on Eelgrass (Zostera marina), but we have no further records from this area. However, in a Rapid Assessment Survey in 2013, this polychaete was found in marinas in Point Judith Pond and Newport (Narragansett Bay), Rhode Island and the Westport River (Buzzards Bay), Massachusetts (Wells et al. 2014).

Invasion History on the Gulf Coast:

In 1942, specimens of Neodexiospira brasiliensis from Biloxi, Mississippi were identified by Hartman as the conspecific 'Dexiospira corrugatus'. Many tubes were found on blades of Turtlegrass (Thalassia testudinum) (Hartman 1951). This population appears to have been established, but we have no further records form the Gulf.

Invasion History Elsewhere in the World:

In Europe, Neodexiospira brasiliensis is often found in association with the invading brown seaweed Sargassum muticum. It was first found on S. muticum and on harbor pontoons in Portsmouth Harbour, England (Kinght-Jones et al. 1975). It was subsequently found at other sites on the south coast of England, along the Solent near Portsmouth (1^st record 1975, Critchley et al. 1983) and in the River Yealm, Devon (1^st record 1976, Critchley et al. 1983). Neodexiospira brasiliensis was found in Cherbourg, France in 1976 (Critchley et al. 1983) and appeared at St. Helier, Jersey, in the Channel Islands (Critchley et al. 1997). Much more extensive spread was noticed in the Netherlands, where dense populations were found at the mouth of the Goessche Sas canal off the Eastern Scheldt estuary in 1982. Settlement was denser on Eelgrass (Zostera marina) than on S. muticum or on the canal walls (Cricthley and Thorp 1985). By 2000, it had spread into Zuid Beveland Canal (Wolff 2005), and became widespread in the southwest Netherlands Delta. In 2009, it was found at Texel, in the Wadden Sea (Gittenberger et al. 2010).

Neodexiospira brasiliensis is established at the tip of South Africa. It was collected at Cape Town in 1953, and Port Elizabeth in 1961 (Knight-Jones and Knight-Jones 1984; Mead et al. 2011b).

Description

Worms of the Spirorbinae (currently considered a subfamily of Serpulidae) are small tubeworms, usually growing in tightly coiled, calcareous tubes (Blake and Ruff 2007; Ten Hove and Kupriyanova 2009). They have a branchial crown of feather-like radioles, as in the other serpulids. The radioles can be folded and withdrawn into the tube. One of the radioles is modified to form an operculum, which acts as a plug when the animal contracts. The peristomium (segment behind the mouth) is folded back to form a collar, which bears uniramous parapodia, with a distinctive set of collar chaetae, with spines or serrations. The collar is the first of three or four asymmetrical thoracic chaetigers. Description based on: Hayward and Ryland 1990 and Blake and Ruff 2007.

The tube of Neodexiospira brasiliensis is coiled dextrally (counter-clockwise when seen from above). Larger tubes often have four equidistant parallel grooves, which are easily seen from above, and are opaque and white. Embryos are brooded in the operculum, which has opaque and thickly calcified walls, except for a transparent zone near the basal disk. When not brooding embryos, the cylindrical-funnel shaped operculum contains a talon which may vary from broadly triangular to axe-shaped. The operculum is covered by a slightly concave distal plate. As the embryos develop, a second distal plate develops beneath the embryos, and a new brood chamber is formed.

The thoracic membrane of N. brasiliensis is fused dorsally, to form a tunnel over the fecal groove. There are three chaetigers in the thoracic region, each with paired bundles of chaetae. Some collar chaetae have a slight knee-like swelling, with a finely toothed edge; there are capillary chaetae mixed among them, comprising about 11 chaetae in each bundle. The third chaetiger contains sickle-like chaetae, again with a knee-like swelling, but with the fine teeth on the curved blade. The longest abdominal chaetae are sickle-like and longer than the collar chaetae, with coarse teeth. The animal forms a coil about 2 mm in diameter. The body color is orange (Image at http://home.kpn.nl/faassema/Neodexiospirabrasiliensis.html). Description based on: Knight-Jones et al. 1975, Knight-Jones and Knight-Jones 1977, Hayward and Ryland 1990, and MarLin 2015.

Potentially misidentified species: Polychaetes of the subfamily Spirorbinae are diverse. For example, at least 7 genera and 13 species are known from the central region of the West Coast (Blake and Ruff 2007). Only the most closely related species are listed below. They are easily overlooked as a result of their small size, and because many key characters are concealed by tube that is easily breakable, as is the worm inside it. Consequently, records are dependent on specialists and frequently sporadic.

Taxonomy

Ecology

General:

Neodexiospira brasiliensis is a small, tube-dwelling, epifaunal polychaete. The worms are hermaphroditic, with male and female gonads. Fertilization occurs outside the body, but inside the tube, where the larvae are brooded in an opercular chamber. Self-fertilization can occur, but is rare (Knight-Jones and Knight Jones 1977; Benkwitt 1981). Larvae are lecithrophic and can settle and begin metamorphosis within 1-5 hours of hatching (Kirchman et al. 1982). Larvae of N. brasiliensis tend to settle on vegetation, including red algae: Ceramium planum; brown algae: Fucus serratus, Sargassum muticum; green algae: Ulva lobata; and seagrasses Zostera marina, Zostera asiatica, Phyllospadix iwatensis (Knight-Jones and Knight-Jones 1975; Nelson 1979; Critchley and Thorp 1997). This worm also occurs on pontoons, mussel and snail shells (Critchley and Thorp 1997). Bacterial films appear to induce settlement (Kirchman et al. 1982). Differing preferences for young (Nelson 1979, North Carolina) or old Zostera leaves (Hamamoto and Mukai 1999) may be related to associated bacteria (Kirchman 1982

Neodexiospira brasiliensis is a wide-ranging, tube-dwelling polychaete, occurring from the lower upper subtidal to at least 137 m depth, and from cold-temperate regions to the tropics (Knight-Jones and Knight-Jones 1975; Rzhavsky 1991). Spirorbinine polychaetes are filter-feeders, feeding on phytoplankton and other suspended particles (Fauchald and Jumars 1979).

Food:

Phytoplankton

Trophic Status:

Suspension Feeder

Habitats

Tolerances and Life History Parameters

General Impacts

References