Chesapeake Bay Introduced Species Database

Diplosoma listerianum

Common name(s):
colonial tunicate
What are colonial tunicates? Tunicates are marine filter feeders that collect food using a pair of siphons. They are attached to a substrate and are protected by a nonliving cellulose layer called a tunic. Colonial tunicates like Diplosoma listerianum have many individuals, called zooids, sharing a single tunic. While each zooid is an individual, they can?t detach from the colony. In fact colonies not only share a tunic but also an excurrent siphon; each zooid pulls water into its own incurrent siphon but pumps it out a shared excurrent siphon. D. listerianum is widely distributed and was described separately in many different countries, each giving it a different species name. Because of this, its native range is unknown. It was discovered near Cape Charles, VA in 2001 and 2002 and is now abundant there. It was also found in Lynnhaven Bay, Virginia Beach VA in 2002.
Image courtesy of Melissa Frey of the Royal Museum in BC.

Chesapeake Bay Status:

First Record
Regular Resident

Source Region
Native Region
Western Atlantic Unknown-Marine

Vector(s) of Introduction
Shipping(Fouling Community)

History of Spread:

The colonial tunicate Diplosoma listerianum was first described from the English Channel by Milne-Edwards in 1841. This species was described, under different names, from many different places around the world, such as Australia (D. rayneri Macdonald 1859) Brazil (D. macdonaldi Herdman 1886), and Japan (D. mitsakurii Oka 1892). These and many other names were synomized by Kott (1990; 2001). In most parts of its present range, including the West Coast (NE Pacific, San Diego CA to Vancover Island, British Columbia) (Lambert and Lambert 2001), and Southeast Coast of North America, (south of Cape Hatteras) D. listerianum has long been considered native. Gretchen Lambert now considers D. listerianum to be a species possibly of Northeast Atlantic origin, probably introduced over most of its range by the beginning of the 20th century (Lambert 2004, personal communication). However, recent invasions of this tunicate are documented on the Northeastern Coast of North America (Gulf of Maine to the Chesapeake Bay). Populations on several Pacific Islands (Pearl Harbor, Oahu, HI), Guam, and New Zealand, are considered to be introduced (Coles et al. 1999; Cranfield et al. 1998; Lambert 2002).

On the East Coast, D. listerianum was collected in 1880 in the Atlantic Ocean off SC, and subsequently found from NC to FL, in the Gulf of Mexico (U.S. National Museum of Natural History 2002; Van Name 1921). Its first reported occurrence north of Cape Hatteras was in Long Island Sound (Groton CT) around 1990 (Whitlach et al. 1995). It was found in Narragansett Bay RI and Vineyard Sound MA in 1998 (Whitlach and Osman 2000), in the southern Gulf of Maine, at Star Island NH, in 1996 (Harris and Tyrell 2001), in Great Bay, near Portsmouth NH in 1997 (Blezard 1999), Cape Neddick ME in 1999, and Portland ME in 2000 (Harris and Tyrell 2001; MIT Sea Grant 2003).

There are no published records of D. listerianum between Long Island Sound and Cape Hatteras. However, specimens of this tunicate were found on fouling plates in lower Chesapeake Bay near Cape Charles VA in 2001, and again in 2002. Identifications were confirmed by Gretchen Lambert. At this site, these colonies appeared to be abundant. In 2002, this tunicate was also found in Lynnhaven Bay, Virginia Beach VA (Ruiz et al., unpublished data).

References- Blezard 1999; Coles et al. 1999; Cranfield et al. 1998; Harris and Tyrell 2001; Kott 1990; Kott 1998; Kott 2001; Lambert and Lambert 1998; Lambert 2002; U.S. National Museum of Natural History 2002; Van Name 1921; Whitlach et al. 1995; Whitlach and Osman 2000

Invasion Comments:

This data was last modified on Tuesday, August 19th, 2008.
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