Botrylloides violaceus

History of Spread

Botrylloides violaceus was described from Japan in 1927. It is found in Northwest Pacific from Japan to southern China. Reports from Queensland, Australia (Kott 1985; Kott 1998) may be a misidentification (Gretchen Lambert, pers. comm. 2000). It is now widely introduced, to the Northeast Pacific, the Northwest Atlantic, and parts of the Northeast Atlantic. It was first recorded on the West coast in San Francisco Bay in 1973 (Cohen and Carlton 1995). Subsequently, it was found in Bahia San Quintin, Mexico (2005, Rodriguez et al. 2008) Ensenada, Mexico (2000), (Lambert and Sanamyan 2001) , San Diego Bay (2000) (Lambert, personal communication) , Coos Bay OR (Lambert, personal communication) , Willapa Bay WA (1980) (Cohen and Carlton 1995), Puget Sound WA (1998) (Cohen et al. 1998), and Prince William Sound AK (Hines et al. 2000; Lambert and Sanamyan 2001). In the Northeast Atlantic, B. violaceus was first collected in 1993, in the Lagoon of Venice, in the Mediterranean Sea (Zaniolo et al. 1998). It has also been found in the Western Scheldt estuary, in the Netherlands, in 2000 (Gittenberger 2007), Zeebrugge, Belgium (Kerkhof et al. 2007), many sites on the southern coast of England (Arenas et al. 2006),and on the eastern coast of Ireland (Minchin et al. 2007).

Botrylloides diegensis, native to the NE Pacific, was introduced to Eel Pond, adjacent to Woods Hole Harbor MA, by a scientist, who wanted a supply of experimental animals. He reported successful overwintering and reproduction of these animals (Carlton 1989). Consequently, later occurrences of Botrylloides sp. in the NW Atlantic have been attributed to this species (Berman et al. 1992). However, later examination of Botrylloides sp. along the Northeast Coast of North America indicates that all the specimens found were B. violaceus (Gretchen Lambert, personal communication 2000).

Since B. violaceus was a very recent and local invader to the Pacific Coast of North America in the 1970s, it is unlikely that this species was introduced to Eel Pond. A separate invasion, in the late 1970s is likely for B. violaceus. The fate of the tranplanted B. diegensis is unknown. They may have died out on their own, or been replaced by B. violaceus. Any later reports of 'B. diegensis' on the East Coast, outside of Eel Pond (Berman et al. 1992; Whitlach and Osman 2000), probably refer to B. violaceus (Gretchen Lambert, pers. comm. 2000).

Owing to the confusion with B. diegensis, the date of first introduction, and the pattern of early spread in the northwest Atlantic is obscure. However, Whitlach and Osman (1995) indicated that B. violaceus was first observed in the late 1970s in Long Island Sound. By 1981, B. violaceus had spread to Great Bay NH, in the Gulf of Maine , and by the mid 1990s, it had reached Penobscot Bay (Whitlach and Osman 2001). In 2004, it was found fouling cultured mussels on Prince Edward Island in the Gulf of St. Lawrence (Locke et al. 2007). We are unsure of its range in estuaries south of Long Island Sound. However, in 2002, Gretchen Lambert confirmed our preliminary identifications of B. violaceus from lower Chesapeake Bay, collected in 2000 and 2001. Specimens were found on settling plates on both the Eastern (Kiptopeke/VA/Chesapeake Bay) and Western shores (Norfolk/VA/Little Creek (Hampton Roads); Poquoson/VA/Hampton Roads; Belle Isle Marina/VA/Rappahannock River; Amoco Refinery, Yorktown/VA/York River) (Ruiz et al., unpublished data).

References: Arenas et al. 2006; Berman et al. 1992; Carlton 1989; Cohen and Carlton 1995; Hines et al. 2000; Gittenberger 2007;Kerkhof et al. 2007; Kott 1985; Kott 1998; Gretchen Lambert, pers. comm. 2000; Gretchen Lambert, pers. comm. 2001; Lambert and Sanamyan 2001; Minchin et al. 2007; Rodriguez et al. 2008; Ruiz et al., unpublished data; Whitlach and Osman 1995; Zaniolo et al. 1998

Invasion Comments