Toxicity of chromated copper arsenate (CCA)-treated wood to non-target marine fouling communities in Langstone Harbour, Portsmouth, UK

The effect of the anti-marine-borer timber preservative chromated copper ar senate (CCA) (a pressure impregnated solution of copper, chromium and arsen ic compounds) on non-target marine fouling animals it as investigated durin g a subtidal exposure trial. Panels of Scots pine treated to target retenti ons of 12, 24 and 48 kg CCA per m(-3) of wood, plus untreated controls were submerged at a coastal site on the south coast of the UK for 6, 12 and 18 months. After each exposure period the fouling communities that formed on t he surface of panels were assessed both qualitatively and quantitatively. C ommunity structure was similar on panels treated to the three CCA loadings, but was significantly different from community structure on untreated pane ls. The total number of species (species richness) it as similar on all pan els, although the number of individual organisms attached to the surface of panels was significantly higher on CCA-treated panels than on untreated pa nels. k-dominance curves revealed that the difference., in numbers of indiv iduals between CCA-treated and untreated panels was caused by higher number s of the dominant species (Elminius modestus, Hydroides ezoensis, and Elect ra pilosa) on CCA-treated panels. Other species were present in similar num bers on panels of all treatments. Results indicate that there are no detrim ental toxic effects to epibiota caused by tile presence of CCA preservative within the matrix of the wood at any of the treatment levels. Differences in community structure between CCA-treated and untreated panels may he due to enhanced larval settlement on CCA-treated timber by some species as a re sult of modifications to the surface properties of the timber by the CCA pr eservative. (C) 2001 Elsevier Science Ltd. All rights reserved.