Download Teredo navalis, Common shipworm - GB non

C o m m o n s h i p w o r m , Teredo navalis
Overview
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Short description of Teredo navalis, C o m m o n s h i p w o r m
This mollusc has a reddish-brown, soft, worm-like, elongated body with a modified
bivalve shell at the anterior tip, adapted for burrowing into wood. It bores tunnels and
excretes a calcareous tube up to 60 cm long where it lives permanently.
Description of Teredo navalis, Common shipworm status in GB
The naval shipworm has been recorded from southeast and southwest coasts of
England, but may be present around all GB coasts.
H a b i t a t s u m m a r y : Teredo navalis, C o m m o n s h i p w o r m
The naval shipworm burrows into submerged wood where it lives embedded in a tunnel
lined with a calcareous, shell-like substance. It can tolerate salinities ranging from 9 40 ppt and temperatures from 0 to 30 °C. Its distribution is widespread in seas and
estuaries throughout the world.
Overview table
Environment:
Marine
Species
status:
Unknown
Native range:
China, Føroyar, Iceland, Kazan-retto, Nansei-shoto,
Ogasawara-shoto, South Korea, Norway, Taiwan
Functional
type:
Filter-feeder
Status in
England:
Unknown
Status in
Scotland:
Unknown
Status in
Wales:
Unknown
Location of
first record:
Pin Mill, River Orwell
Date of first
record:
1992
GB Distribution from N B N G a t e w a y
Author's name:
Natalie Sweet
Last updated:
March 31st, 2011
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Invasion history: Teredo navalis, C o m m o n
shipworm
Origin
The historic native distribution is uncertain as the naval shipworm has been
transported by ships for centuries. There is little agreement between authors; some
suggest an Indo-Pacific origin, and others believe it may be native to the Atlantic.
First Record
The naval shipworm was first recorded in Europe in 1731, from wooden dyke gates in
The Netherlands. The date of its first occurrence in GB is unknown but it was
described as part of the British mollusca by Forbes & Hanley in 1853.
Pathway and Method
The naval shipworm is thought to have been transported in the wooden hulls of ships
and in driftwood for many centuries. Larvae are free swimming in the water column
and in driftwood for many centuries. Larvae are free swimming in the water column
for around two weeks; during this time they may be dispersed naturally by water
currents and unintentionally carried within ships’ ballast water.
Species Status
The naval shipworm has been recorded from the English Channel and North Sea
coasts. It is found widely throughout the Atlantic and Pacific Oceans. More recently it
has been reported from the Baltic, Black and Mediterranean Seas.
Ecology & Habitat: Teredo navalis, C o m m o n
shipworm
Dispersal Mechanisms
Larvae are planktonic for approximately two weeks during which time they are
dispersed by currents and may be transported within ships’ ballast water. Adults are
widely dispersed with floating wooden objects/structures including driftwood and
wooden ships’ hulls.
Reproduction
The female carries the young embryos within the gill chamber for a short period where
they pass through the early stages of larval development before releasing them.
Larvae have a free swimming period of about two weeks before entering a piece of
wood and creating a burrow. After settling, metamorphosis is rapid and the juvenile
reaches sexual maturity and spawns within six to eight weeks. The species is very
prolific, spawning three or four times per season and releasing 500,000 to 1,000,000
eggs at a single spawning.
Known Predators/Herbivores
Living permanently and securely inside timber, the naval shipworm is protected from
predators, but the pelagic larvae are exposed to predation.
Resistant Stages
None known.
Habitat Occupied in GB
The naval shipworm occupies tunnels bored into submerged wooden objects or
structures, including piers, harbours, ships’ hulls, groynes and driftwood.
Distribution: Teredo navalis, C o m m o n s h i p w o r m
Native range is unclear; it is unknown whether it invaded Europe from South East Asia
or whether it originated in Europe and extended its range through the rest of the
world. In GB there are records from the south west to south east coasts but the
species may occur all around GB coasts.
I m p a c t s : Teredo navalis, C o m m o n s h i p w o r m
Environmental Impact
None known.
Health and Social Impact
In Holland during the 1970s the naval shipworm was responsible for the destruction of
large parts of the country’s dike system (sea defences), resulting in widespread
flooding following a storm in 1731. Viking vessels and other shipwrecks of historic
interest in the Baltic Sea have been attacked by naval shipworms since the species’
establishment in the Baltic Sea during the 1930s.
Economic Impact
Potential economic impacts are significant as the naval shipworm can bore into
unprotected wooden structures and cause considerable damage undetected due to the
tiny entry and siphon hole. Its appearance in San Francisco Bay resulted in over $900
million damage to piers and wharfs during 1919-1921, and current estimates suggest
$200 million damage is still occurring in this area annually. The most efficient way to
avoid economic losses may be to rebuild coastal structures using non-wooden
materials in submerged parts.
References & Links: Teredo navalis, C o m m o n
shipworm
Identification
Forbes, E. & Hanley, S. (1853) A History of British Mollusca and their shells, Volume 1,
London, John van Voorst.
Rowley, S. (2005) Teredo navalis. Great shipworm. Marine Life Information Network:
Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine
Biological Association of the United Kingdom. Available from:
http://www.marlin.ac.uk/speciesinformation.php?speciesID=4447
Biology, ecology, spread, vectors
Culha, M. (2010) The Presence of Teredo navalis Linnaeus, 1758 (Mollusca, Bivalvia,
Teredinidae) in the Southern Black Sea, Turkey. Journal of Animal and Veterinary
Advances, 9 , (10), 1515-1518.
Grave, B.H. (1928) Natural history of shipworm, Teredo navalis, at Woods Hole,
Massachusetts. Biological Bulletin, 5 5, 260-282.
Lebour, M.V. (1946) The species of Teredo from Plymouth waters. Journal of the
Marine Biological Association of the United Kingdom, 2 6, 381-389.
Tuente, U., Piepenburg, D. & Spindler, M. (2002) Occurrence and settlement of the
common shipworm Teredo navalis (Bivalvia: Teredinidae) in Bremerhaven harbours,
northern Germany. Helgoland Marine Research, 5 6, 87-94.
Management and impact
Didžiulis, V. (2007) NOBANIS – Invasive Alien Species Fact Sheet – Teredo navalis.
Database of the North European and Baltic Network on Invasive Alien Species NOBANIS [online] Available from:
http://www.nobanis.org/files/factsheets/Teredo_navalis.pdf
Hoppe, K.N. (2002) Teredo navalis – the cryptogenic shipworm. In: Leppakoski, E.,
Gollasch, S., & Olenin, S. (editors) Invasive species of Europe. Distribution, impacts
and management. Dordrecht/Boston/London, Kluwer Academic Publishers, 116-119.
General
Hoppe, K.N. (2002) Teredo navalis – the cryptogenic shipworm. In: Leppakoski, E.,
Gollasch, S., & Olenin, S. (editors) Invasive species of Europe. Distribution, impacts
and management. Dordrecht/Boston/London, Kluwer Academic Publishers, 116-119..