Impact on non-target organisms of anti-marine wood-borer treatments

Treatment of wood with a mixture of copper, chrome and arsenic salts (CCA) is used to prevent the settlement of wood-boring invertebrates. The efficacy of treatment is due to toxicity to the borers, so there is concern that preservatives may have undesirable impacts on non-target biota. This study aims to provide and assess the environmental risk posed by the use of treated wood in coastal installations. CCA-treated wood samples have been prepared to target retentions of 12, 24 and 48 kg CCA/m ³ of timber. Racks of plasticiser-free plastic have been prepared on each of which are randomly arranged two replicates of each target retention plus two untreated controls. Rates of leaching of CCA components from these samples are being measured at marine sites in West Sweden, the South Coast of the UK, the West Coast of fRance, southern Portugal and Athens. The rate of release and sequestration of CCA components by soft rot fungi and lignolytic bacteria is also being assessed. These data will be combined to predict the rate of leaching beyond the time limits of the project. Impacts of CCA-leachate may occur at the wood-water interface, in the water column or in nearby sediments. Epibiotic forms provide evidence of effects at the wood preservative/seawater interface, where the flux of leachate is highest. The acute effects of this flux are being evaluated at 6 month intervals by monitoring settlement of epibiotic organisms, the chronic effects by measuring their growth rates. Chronic effects on the physiology of Mytilus have also been measured. Impact on planktonic organisms will be assessed by measuring effects of leachate on the behaviour of bivalve veligers. Toxicity testing methods for benthic organisms are being modified to reflect the particular needs of investigating the impact of wood preservatives. Uptake and storage of components of the CCA by epibiota is being analysed.