Validating a short-term laboratory method to assess the resistance of timber to biodegradation by marine wood-borers
L S Martin, J R Shipway, G P Malyon, S M Cragg
Novel approaches to protecting wood in coastal and marine environments are needed as the use of traditional broad-spectrum biocides are now restricted. Wood is widely utilised in marine environments where it can be rapidly degraded by wood-boring organisms, causing billions of dollars of damage per annum. Biocidal compounds such as CCA and creosote have been popular treatments for timber products during the last century but have since been restricted or banned in several countries, including the UK. Novel methods in wood modification and protection are therefore required to replace such techniques. Use of lesser-utilised timber species and wood modification offers a promising alternative approach of reducing damage by marine wood-borers. Processes of modification are evolving rapidly, so long-term testing needs to be supplemented by rapid testing methods in order to speed up process development. New potential products must undergo thorough testing in order to be commercially viable and to minimise environmental impacts. Marine trials require long exposure periods and are thus expensive and slow to yield meaningful results. Laboratory tests, however, provide a much quicker alternative to test novel timber products against gribble attack. A standard method for assessing the feeding rate of the wood-boring crustacean the gribble (Limnoria spp.) can be used to determine if the wood affects feeding rate and mortality. This is investigated through assessing faecal pellet production (used as an indicator of feeding rate), vitality, and mortality rates. These data combined, can begin to identify products that have the potential to be resistant marine wood-borer attack.