Economic effects Teredo navalis

destruction teredo worm in tree branch.

teredo navalis destructive pest of submerged timber. in baltic sea, pine trees can become riddled tunnels within 16 weeks of being in water , oaks within 32 weeks, whole trees 30 centimetres (12 in) in diameter being warped within year. ships timbers attacked, wrecks destroyed , sea defences damaged. around 1730 in netherlands, shipworms found weakening wooden dike revetments, , prevent erosion of dikes , subsequent flooding disasters revetments had replaced heavy stones, @ great expense. shipworm s arrival in san francisco bay around 1920 heralded great destruction piers , wharves of harbours. has spread in pacific ocean greater tolerance of low salinity levels has caused damage in areas unaffected native shipworms.

in eighteenth century british royal navy resorted coppering bottoms of ships in attempt prevent damage caused shipworm.

no treatment of timber prevent attack teredo navalis has been successful. experiments dutch in 19th century proved inefficacy of linseed oil, metallic paint, powdered glass, carbonization (i.e., burning outer layers of wood), , of usual biocides such chromated copper arsenate. attempted covering wooden pylons precisely arranged iron nails, had no lasting effect. in 1878 discovered creosote effective deterrent, though work best had applied soft, resinous woods pine; in order work on harder woods such oak, special care had taken ensure wood permeated creosote. submerged wrecks have been protected wrapping them in geotextiles provide physical barrier larvae or reburying them in sediment. no permanent solution has been found..