Effects of Chromated Copper Arsenate (CCA) Wood Preservative on Early Fouling Community Formation

Abstract

The effects of the anti-marine-borer timber preservative CCA (a pressure impregnated solution of copper, chromium and arsenic compounds) on early fouling community formation were investigated during a number of field trials. The formation of a biofilm on the surface of CCA-treated and untreated timber panels of Scots pine was examined by scanning electron microscopy following submersion in Langstone Harbour, Portsmouth, UK for periods of 2, 7, 14 and 28 days. Results indicated a slightly faster rate of biofilm formation after 2 and 7 days of exposure on untreated timber compared to CCA-treated timber, although no differences were visible between panels after 14 and 28 days exposure, or between panels treated to different CCA loadings after all exposure periods. Settlement of the serpulid Ficopomatus enigmaticus and two species of barnacles ( Elminius modestus and Balanus crenatus) onto the surface of untreated and CCA-treated panels of Scots pine was examined following 4 weeks exposure in a brackish water millpond at Emsworth, West Sussex. Numbers of individuals were higher on CCA-treated panels than on untreated panels, and in the case of F. enigmaticus abundance of individuals increased with increasing preservative loadings. Early colonization by macroalgal species on the surface of CCA-treated and untreated panels of Scots pine was examined following submersion of panels in Langstone Harbour for a period of 4 weeks. Percentage cover of most species of algae was similar on the surface of CCA-treated and untreated panels, with the exception of Hincksia granulosa and Ceramium nodulosum which had significantly higher percentage cover on untreated panels. Possible explanations for the recruitment patterns are discussed.