Chesapeake Bay Introduced Species Database

Teredo navalis

Common name(s):
Naval Shipworm
Naval Shipworms are bivalves (like clams) that look like worms. They don?t use their shell for protection; rather they use it as a tool to burrow into wood. They live in the burrow they create in the wood, poking their heads out to feed. Historically these shipworms made their homes in the hulls of wooden ships and traveled the world. Because wooden ships have moved these species around the world for so long, it is difficult to say where they originated and where they were introduced. We believe Naval Shipworms are introduced to the East Coast because reports of this species were confined to ships and shipwrecks, but were absent in natural areas and in wood of a 5,000 yr-old fishweir in Boston, through a similar native species (Bankia gouldi) was found. Naval Shipworms were first seen in the Elizabeth River in 1878 under in debris from a wharf. In the late 1940s and early 1950s, they were reported in Chincoteague Bay, Ocean City MD, and Hampton Roads, Norfolk and Portsmouth VA.
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Economic Impacts

Boating; Industry
Teredo navalis (Naval Shipworm) is uncommon in Chesapeake Bay proper, and is probably not a major contributor to the deterioration of wooden structures there. It was rare in Chincoteague Bay, but abundant in test boards at Ocean City, where it appeared to pose a serious threat to wooden structures (Scheltema and Truitt 1956). This shipworm is economically important in the Atlantic waters adjacent to the Chesapeake Bay.

References- Scheltema and Truitt 1956

Economic Impacts Outside Chesapeake Bay

Teredo navalis (Naval Shipworm) is probably the most widespread marine wood borer in the world, and has been a major factor in human maritime activities for many centuries (Turner 1966). In the 18th century in the Netherlands, shipworms caused extensive damage to wooden seawalls, which had to be replaced by stone. The worms were declared to be a plague sent by God (Reise et al. 1999). In the 1920s, an outbreak of T. navalis in San Francisco Bay caused an estimated $615 million dollars (in 1992 dollars) in damage (Cohen and Carlton 1995). In 1946, shipworms were reported to cause an annual $55 million ($500 million in current dolars) of damage to waterfront structures in United States, 1946 (Clapp 1946, cited by Scheltema & Truitt 1954).

References- Cohen and Carlton 1995; Reise et al. 1999; Scheltema and Truitt 1954; Turner 1966

Ecological Impacts

Impacts on Natives:
Competition; Habitat Change; Herbivory
Ecological impacts of Teredo navalis (Naval Shipworm) on native biota may be limited by its low abundance in the Bay proper, but it is an abundant and important woodborer in adjacent Atlantic waters (Scheltema and Truitt 1956).

Competition with the native Bankia gouldi (Gould's Shipworm) is possible, but has not been documented. Competition would be restricted to polyhaline parts of the lower Bay, because of T. navalis' preference for high salinities (Brown 1953; Wass et. al. 1972). In Barnegat Bay, both species overlap, but B. gouldi dominates in the western parts of the bay while T. navalis is the predominant form in the more saline inner parts (Richards et al. 1984).

Habitat Change - Boring animals may alter habitats by breaking up woody debris, opening cavities, etc., permitting other animals to use the wood for shelter (Turner 1984).

Herbivory - Boring animals speed the recycling of wood in the marine environment, allowing it to enter foodwebs (Turner 1984).

References - Brown 1953; Richards et al. 1984; Turner 1984; Wass et. al. 1972
Impacts on Non-natives:
Competition; Habitat Change
Ecological impacts of Teredo navalis (Naval Shipworm) on exotic biota may be limited by its low abundance in the Bay proper, but it is an abundant and important woodborer in adjacent Atlantic waters (Scheltema and Truitt 1956).

Competition - Competition is possible with T. bartschi (Bartsch's Shipworm) and T. furcifera, but has not been documented. Probably, temperature and salinity are more important limiting factors for the subtropical species (Hoagland 1986; Richards et al. 1984).

References - Hoagland 1986; Richards et al. 1984; Scheltema and Truitt 1956

This data was last modified on Thursday, September 29th, 2005.
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