Shipworms are Teredinid bivalves that have a highly modified shell for boring into wood and an elongated, vermiform shape. Teredinids are marine wood-borers, utilising timber as both shelter and as a source of food. Wooden structures in the sea, such as piers and sea defences, are subject to severe damage by these borers, costing billions per year for maintenance and replacement. Traditionally, broad-spectrum biocides have been used to protect timber, however, treatments like CCA (chromated copper arsenate) and creosote are now restricted by legislation in Europe. In response, alternative methods to reduce marine borer attack have been explored, including chemical wood modifications, like furfurylation. This technique is non-biocidal and has been well proven for uses in terrestrial environments. However, products are continuously being tested for protecting wood against marine borers. Changes to the exact mixes used, retention levels and curing procedures affect the service life of these materials, so testing is performed to the European standard EN275. This standard however, currently involves only long-term marine field testing where products are rated based on the extent of damage by mature shipworm. More rapid testing provides a quicker insight into the efficacy of novel treatments and allows for flexibility to adjust mixes and procedures. Here, we evaluate small wood blocks after 5 and 10 weeks of deployment in Venice lagoon, where the most common species are Lyrodus pedicellatus, Lyrodus c.f. mersinensis, Teredo navalis and Teredo batschi. Under a stereomicroscope, hemispherical bore holes left by larval settlement attempts were counted and any successful metamorphosis was noted. After 5 weeks, control wood had a higher number of attempts but by 10 weeks, modified wood had significantly more attempts, as by then, successful settlement (metamorphosis) on the control was more common than failure. When compared to the longer-term trials as described in EN275, after several years of exposure, shipworm recruitment begins to increase on these treated woods and adults can be seen by x-ray imaging. Being able to disrupt settlement at this early stage of the life cycle will reduce recruitment and by consequence, damage by adult shipworm.

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