Spirobranchus minutus

Invasion History

First Non-native North American Tidal Record: 1946
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record: 1946

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General Invasion History:

Spirobranchus minutus was described from the Pacific coast of Mexico in 1942, where it was recorded in shallow water on shells, pilings, corals, floating seaweed, and boat hulls. On the Pacific coast, it ranges from Baja California to Peru and northern Chile (Rioja 1942, cited by Bastida-Zavala et al. 2017). In 1946, it was collected from Veracruz on the Gulf Coast of Mexico (Rioja 1946, cited by Bastida-Zavala et al. 2017), and is known from the Gulf Coast of Florida and Texas. In the Atlantic, its distribution extends to Sao Paulo state, Brazil (Zibrowius et al. 1970; Perkins 1998; Bastida-Zavala et al. 2016; Bastida-Zavala et al. 2017; U.S. National Museum of Natural History 2017). Spirobranchus minutus is considered probably introduced by shipping from the East Pacific to the western Atlantic (Bastida-Zavala et al. 2016; Bastida-Zavala et al. 2017).

North American Invasion History:

Invasion History on the Gulf Coast:

Spirobranchus minutus was included on a checklist of polychaete species found in Florida in 1998, but there were no further details (Perkins 1998). In 2000, it was found on Smithsonian fouling plates in Pensacola Bay, Florida, where it was abundant, and Galveston Bay, Texas, where it was occasional. This worm was also abundant in Corpus Christi Bay, Texas in 2002 (Bastida-Zavala et al. 2017).

Invasion History Elsewhere in the World:

Spirobranchus minutus seems to have a more continuous distribution in the Eastern Pacific than in the Western Atlantic, where the distribution is spotty. However, genetic studies are needed to establish whether the populations in the two oceans are genetically similar or distinct (Bastida-Zavala et al. 2017). The first Atlantic specimens were collected in 1961-1965 in São Sebastião, Ubatuba, and Santa Catarina, Brazil (Zibrowius 1970; USNM 43239, U.S. National Museum of Natural History 2017). Other South American records are from Venezuela (Playa Grande Choroni, and Higuerote beaches) (Weisbord 1964 cited by Bastida-Zavala et al. 2017), and Surinam (from 1969, USNM 55847, U.S. National Museum of Natural History 2017). In the Caribbean, S. minutus was found at several sites in the Caribbean in 1978 (USNM 55848-55851, U.S. National Museum of Natural History 2017). Ballast water and hull fouling are likely vectors for transport. Specimens are known from the hull of a yacht that sailed from Mexico and California to Hawaii (Bastida-Zavala 2008), and from a sail-training ship that travelled from Mexico to Sydney, Australia (Lewis et al. 2006).

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Description

Spirobranchus minutus secretes a calcareous tube, as do other serpulid polychaetes. Serpulids have a feathery crown of modified prostomial palps, called radioles (the prostomium is the first segment, projecting above the mouth). 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 seven thoracic chaeta-bearing segments (setigers). The subsequent segments have biramous parapodia. The dorsal branch of the parapodium is called the notopodium and the ventral branch is the neuropodium. Chaetae in the two branches and along the body can vary greatly in their morphology, which can be critical in the taxonomy of serpulids. This description is based on ten Hove and Weerdenburg 1978; Barnes 1983; Blake and Ruff, in Carlton 2007.

The tube of S. minutus is white and thick-walled, with three prominent longitudinal ridges, with rows of alveoli between them, but without peristomes. Tubes described or illustrated in the literature were ~5-6 mm in size (Zibrowius 1970; Bastida-Zavala et al. 2008; Bastida-Zavala et al. 2017). The peduncle of the operculum has thin distal wings, which are missing in a few specimens. The operculum is conical, with a rounded, calcareous distal plate. Some specimens have two rounded masses on the distal plate. The branchial crown is composed of 5-9 radioles on each of the two lobes. The thoracic membrane is long and large, extending to the last thoracic membrane. The collar usually bears 2-3 hooded limbate (with a flattened, wing like edge) chaetae, but sometimes the chaetae are lacking altogether. Preserved specimens do not show pigmentation, except for a white band around the base of the branchial crown (Zibrowius 1970; Bastida-Zavala et al. 2008; Bastida-Zavala et al. 2017). Tubes can reach a length of 44 mm with a width of 3 mm, and up to 40 radioles in each lobe of the branchial crown (Monro 1933, cited by Zibrowius 1970). Smaller specimens (tubes 8-7 mm in length) have 9-24 radioles per lobe (Zibrowius 1969; Bastida-Zavala et al. 2017). The radioles have rounded processes at the end of the inter-radiolar membrane. Serpulids of the genus Protula lack an operculum and an opercular peduncle. The thoracic membrane is well-developed and extends to the last thoracic chaetiger, and is well developed. The abdomen has geniculate (bent, knee-like) chaetae, and uncini (stout, deeply embedded beak-like chaetae), with numerous rasp-like teeth. Living animals are a pale orange-pink, with bright red spots on the radioles and a bright red thoracic membrane. They also have a yellow dorsal caudal gland (Zibrowius 1970; Bastida-Zavala et al. 2017).

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Taxonomy

Ecology

General:

The serpulid tubeworm Spirobranchus minutus, like most serpulids, feeds by extending its feathery gills and trapping plankton in the water column, which are transported by cilia to the mouth. Specific details of reproduction in S. minutus are unknown, but most serpulids have separate sexes, and planktotropic larvae, with varying planktonic periods (Barnes 1983).

Spirobranchus minutus appears to be limited to subtropical and tropical climates. Most records are from intertidal and shallow waters, but P. balboensis has been collected at depths down to 42 m. It has been found on rocky shores, mollusk shells, corals, mangrove roots, floating algae, marinas, pilings, boat hulls, and fouling plates (Bastida-Zavala et al. 2017).

Food:

Phytoplankton, detritus

Trophic Status:

Suspension Feeder

SusFed

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Habitats

General Habitat	Marinas & Docks	None
General Habitat	Oyster Reef	None
General Habitat	Rocky	None
General Habitat	Mangroves	None
General Habitat	Coral reef	None
General Habitat	Vessel Hull	None
Salinity Range	Polyhaline	18-30 PSU
Salinity Range	Euhaline	30-40 PSU
Tidal Range	Subtidal	None
Tidal Range	Low Intertidal	None
Vertical Habitat	Epibenthic	None

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Tolerances and Life History Parameters

Maximum Length (mm)	6	Published information on size range is limited- this was the the largest specimen found by Zibrowius (1970), and close to the estimated size of tubes illustrated by Bastida-Zavala et al. 2017).
Broad Temperature Range	None	Subtropical-Tropical
Broad Salinity Range	None	Polyhaline-Euhaline

General Impacts

No impacts have been reported for introduced or native populations of Spirobranchus minutus.

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References

Barnes, Robert D. (1983) Invertebrate Zoology, Saunders, Philadelphia. Pp. 883

Bastida-Zavala, J. Rolando. (2008) Serpulids (Annelida: Polychaeta) from the Eastern Pacific, including a brief mention of Hawaiian serpulids., Zootaxa 1722: 1-61

Baurick, Tristan (4/13/2017) Scientists identify pest laying waste to Mississippi River Delta wetlands grass, Times-Picayune <missing volume>: Publishedonline

Blakeslee, April M. H.; Miller, A. Whitman; Ruiz, Gregory M.; Kerstin Johannesson · Carl André ·Johannsson, Kerstin;· André, Carl; Panova, Marina (2021) Population structure and phylogeography of two North Atlantic Littorina species with contrasting larval development, Marine Biology 168: <missing location>

Lewis, John A.; Watson, Charlotte; ten Hove, Harry A. (2006) Establishment of the Caribbean serpulid tubeworm Hydroides sanctaecrucis Krøyer [in] Morch, 1863, in northern Australia., Biological Invasions 8: 665-671

Louisiana Wildlife, Federation 2017 Roseau cane pest continues to plague Louisiana’s coast with no signs of slowing down. <missing URL>



Lux, Travis 2017 Shipping industry worries as tiny bug threatens marsh. <missing URL>



U.S. National Museum of Natural History 2002-2021 Invertebrate Zoology Collections Database. http://collections.nmnh.si.edu/search/iz/



Wesselingh, Frank P. and 20 authors (2019) Mollusc species from the Pontocaspian region- an expert opinion list, ZooKeys 824: 31-124

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