SETTLEMENT OF FICOPOMATUS ENIGMATICUS (POLYCHAETA, SERPULIDAE) ON PRESERVATIVE-TREATED WOOD
Brown, C. J.; Thorp, C. H. & Eaton, R.
School of Biological Sciences, University of Portsmouth, King Henry Street. Portsmouth, PO1 2DY UK
Traditionally the use of constructional timber in seawater situations has depended on naturally durable wood species and on less durable species treated with the appropriate wood preservative chemicals. The availability of natural durable species has declined significantly in recent years, resulting in an increased use of timber treated with the highly fixed cooper-chrome-arsenic (CCA) preservatives, sometimes in combination with creosote. The effectiveness of CCA in protecting timber against marine boring molluscs, crustaceans, and the lignolytic microflora on the wood surface is widely documented. However, relatively little is known about the influence of the preservative components on non-target fouling organisms, either through their direct contact with the wood surface or through exposure to preservative leachate. Studies have been initiated to evaluate the effect of CCA on the settlement of a range of macrofouling organisms including Bryozoa, serpulid polychaetes, barnacles and ascidians. The availability of a convenient population of the serpulid, Ficopomatus enigmaticus, provided a means to test the effect of CCA preservative against the settlement of this known fouling species on treated wood surfaces. Predictable heavy settlements (frequently >10 6 m ²) of F. enigmaticus allowed enumeration of the organisms on the test panel surfaces after 2 weeks of submergence. Compared to other fouling organisms, heavy settlements together with the short exposure period makes F. enigmaticus an attractive test organism for rapid ecotoxicological studies. Using Scots pine test panels treated to a range of CCA retentions frm 0 to 48 kg/m³, settlement density of F. enigmaticus increased significantly with increased preservative loading. Possible interpretations of this enhanced settlement with increasing CCA levels are discussed in relation to other published works on settlement of fouling organisms on wood surfaces.