Medieval Shipwrecks under threat from Shipworms

Shipworms, commonly referred to as 'termites of the sea', are launching an attack on the Baltic Sea, putting large maritime archaeological sites at risk. Researchers from the University of Gothenburg in Sweden, currently participating in the EU-funded WRECKPROTECT project to investigate which artefacts are at risk, speculate that climate change is responsible for this threatening tide of shipworms.

The WRECKPROTECT ('Strategies for the protection of shipwrecks in the Baltic Sea against forthcoming attack by wood degrading marine borers. A synthesis and information project based on the effects of climatic changes') project has received over EUR 750,000 in financial support under the 'Environment' Theme of the Seventh Framework Programme.

The project partners aim to provide efficient tools for protection of potential decay areas in the Baltic Sea including covering the shipwrecks with geotextiles and bottom sediment, as well as to formulate guidelines for shipwreck protection. The researchers believe the Baltic Sea is home to around 100,000 well-preserved shipwrecks.



Despite their name, shipworms are actually a group of saltwater clams. They are infamous for boring into and destroying wooden structures that are exposed to sea water. The destruction can be quick or take a longer period, but experts suggest that complete destruction of the archaeological finds can occur within a decade. The shipworm, which can live up to 4 years, can form up to 30 centimetre deep tunnels in all types of wood.

The WRECKPROTECT partners say that the low salinity of the Baltic Sea has for many years safeguarded artefacts that are immersed in the water. Any damage sustained by the underwater cultural heritage to date has been due to fungi, bacteria and microorganisms. While detrimental to the area, their damaging effects are not as potent or quick as those of the shipworms.

The researchers have noted a growing presence of the shipworms along the Danish and German Baltic Sea coasts. Experts say there are 65 species of the shipworm in the world.

'The shipworm has, for example, attacked shipwrecks from the 1300s off the coast of Germany, and we are also starting to see its presence along the Swedish coast, for example, at the Ribersborg cold bath house in Malmö,' explained Christin Appelqvist, a PhD student with the Department of Marine Ecology at the University of Gothenburg.

The most probable culprit for this latest phenomenon is climate change, according to the researchers. The shipworms are likely adapting to the lower salinity in the water because of the rise in water temperature, they say.

'Around 100 wrecks are already infested in the Southern Baltic, buy yet it hasn't even spread past Falsterbo,' Ms Appelqvist pointed out. 'We know it can survive the salinity of the Stockholm archipelago, although it needs water with higher salinity than that to be able to reproduce.'

Coordinated by the SP Technical Research Institute of Sweden, WRECKPROTECT brings together researchers from Denmark, Germany, France, the Netherlands and Sweden. The project is scheduled to end in 2011.

Click here to go to WRECKPROTECT website.