Shipworms eat through wooden groynes and piles on Schleswig-Holstein coasts, eucalyptus hardwood used as defence
Shipworms are causing decay of wooden piles and groynes along parts of Schleswig-Holstein's North Sea and Baltic Sea coastlines, prompting the use of eucalyptus hardwood as a replacement material.
The infestation
The shipworm, a wood‑boring mussel, is causing what authorities describe as partly radical decay of wooden structures along the North Sea and Baltic Sea coasts of Schleswig‑Holstein. Affected structures include groynes, bollards and fascines in harbours and coastal areas. The problem is not new but continues to pose a threat to older wooden coastal protection works.
Also on the North Sea, groynes, bollards and fascines in harbours and coastal areas are repeatedly affected and destroyed by the voracious mussels.
Damage in specific locations
Several locations have seen notable damage. At Kappeln on the Baltic coast, the herring fence was eaten through by the shipworm a few years ago and had to be replaced. On Sylt, wooden piles at List were replaced 10 to 15 years ago after being damaged by both the shipworm and the gribble (Limnoria lignorum).
Among other things, they were damaged by shipworm and the gribble (Limnoria lignorum).
Countermeasures with eucalyptus
When wooden groynes are renewed, the state environment ministry says a particularly resistant wood is now employed. Eucalyptus, a hardwood species, is increasingly used as a replacement to withstand the boring organisms.
When renewing wooden groynes, eucalyptus hardwood is often used.
State‑owned coastal protection structures
State‑owned coastal protection facilities in the region appear largely unaffected. The Landesbetrieb für Küstenschutz, Nationalpark und Meeresschutz Schleswig‑Holstein (LKN.SH) stated that its groynes and other hydraulic engineering works are generally built from stone, concrete or reinforced concrete, making them immune to shipworm damage.
Groynes and other hydraulic engineering structures of the state of Schleswig‑Holstein in this area are generally made of stone, concrete, or reinforced concrete.
This means the infestation remains a problem mainly for older, non‑state wooden infrastructure, while newer and more robust materials keep the primary coastal defence line intact.
