New methods for estimating the volume of shipworm tunnels supported by image analysis

In marine environment, the main threat for wood is the bioerosion by woodborers, both peracarid crustaceans (such as gribbles Limnoria and pincher scuds Chelura) and bivalve molluscs (shipworms, Teredinidae). The damage caused by gribbles on wood structure is surficial and easy identifiable, whereas the damage caused by shipworms is internal, therefore not evident, inducing unexpected crashes with consequence for navigation safety. To give an estimation of the volume eroded by shipworms from conventional X-ray pictures, a model was elaborated from shell size measured on radiographs. A simple method to compare wood poles of different shapes and dimensions is also presented based on image analysis. The methods here presented can be used to study shipworm attack and give new tools for implementing the current standard EN275, avoiding subjective visual assessments and to speed-up the analysis.