Teredo navalis

History of Spread

The status of Teredo navalis (Naval Shipworm) in Northwest Atlantic waters has been debated, but we feel that historical evidence supports the introduction of this shipworm to both sides of the Atlantic (Coomans 1962; Reise et al. 1999). Teredo navalis was definitely introduced to the Northeast Pacific and probably to many other parts of the world in the hulls of wooden ships (Carlton 1992). Carlton (1992) treated this species as: 'Cryptogenic in NW Atlantic; early American records include reports both from visiting vessels (Russell 1839; MA) and from established populations (DeKay 1843; NY).' Subsequently, re-examination of historical evidence has caused Ruiz et al. (2000) to change the status of this species to a definite introduction.

The reasons for treating this species as a clear introduction are: (1) Established populations referred to by DeKay (1843) south of NY were probably B. gouldi, which was apparently not distinguished from T. navalis before the 1860s. The description of Bankia fimbriata (as Xylotria fimbriata) clarified distinctions between two groups of coastal shipworms, and provided a name which was then used for the animal later described as B. gouldi (Tryon 1862; Tryon 1873). Tryon mentions that these species were formerly confused. (2) Early reports of T. navalis from New England are confined to ships; e.g. 'Found in the sheathing of vessels from foreign seas' (Russell 1839) 'From a British frigate sunk during the Revolutionary war' (Tryon 1862); 'The only locality in which I have found this species is an old half-buried wreck near the entrance of the harbor' (Perkins 1871). By the late 19th century, it apparently became widespread in New England waters (Verrill and Smith 1874; Johnson 1915). (3). Teredo navalis was absent in wood of a 5,000 yr-old fishweir in Boston, though B. gouldi was found (Johnson et al. 1942). (4). Teredo navalis was treated as an introduced species in the North Sea (Reise et al. 1999), where its introduction was apparently responsible for a massive attack on Dutch dikes in the 17th century. This species has been transported by ships for so many centuries that its native region is unknown.

Northwest Atlantic records are summarized below:

Gulf of Maine In ports of Essex County MA (Massachusetts Bay), 1839, T. navalis was 'found in the sheathing of vessels from foreign seas' (Russell 1839). Later, it was abundant in test boards at Halifax Nova Scotia, Portland ME, and Boston MA, in 1945-52 (Brown 1953).

Woods Hole, MA (Vineyard Sound; Buzzards Bay) - The first published record is from Verrill (1871). 'The common species of shipworm at Woods Hole as identified by Koifoid and Clapp is Teredo navalis. The date of its first appearance in the region is not known' (Grave 1928). It was abundant in test boards at Woods Hole from 1936-52 (Brown 1953).

Long Island Sound- The first record of T. navalis is from New Haven Harbour CT in 1869 'The only locality in which I have found this species is an old half-buried wreck near the entrance of the harbor' (Perkins 1871). It was abundant in test boards at Fishers Island and various sites around New York Harbor, 1934-52 (Brown 1953).

Chesapeake Bay-adjacent Ocean Regions- Teredo navalis was rare in Chincoteague Bay, but abundant at Ocean City MD in 1952 (Scheltema and Truitt 1956).

Chesapeake Bay (Lower Bay) - At Fort Wool, 1878; 'Broken shells of this creature occur among the rubbish at the bottom of the water. It is quite common in the Elizabeth River and will no doubt be found in the submerged part of the piles which support the wharf' (Uhler 1878). It was also reported from Hampton Roads, 1949 (Ferguson and Jones 1949). Andrews (1956) stated that 'Teredo navalis is rare in the Chesapeake Bay and is not the common shipworm', but specimens of T. navalis were found in test boards in the Elizabeth River, 1944-52, at Norfolk and Portsmouth VA. They were not found in test boards at Lee Hall in the James River, or at Baltimore or Annapolis (Brown 1953).

South of Chesapeake Bay, T. navalis is found in coastal waters of NC and southward to FL, TX, the Bahamas, and Puerto Rico (Brown 1953).

History References - Andrews 1956; Brown 1953;Carlton 1992; DeKay 1843 Coomans 1962; Ferguson and Jones 1949; Grave 1928; Johnson 1915; Johnson et al. 1942; Perkins 1871; Reise et al. 1999; Russell 1839; Scheltema and Truitt 1956; Tryon 1862; Tryon 1873; Uhler 1878; Verrill and Smith 1874; Wass et. al. 1972.

Invasion Comments