FOULING, SURFACE BACTERIA AND ANTIBACTERIAL AGENTS OF 4 BRYOZOAN SPECIES FOUND IN TASMANIA, AUSTRALIA

Extracts from four species of bryozoans, found in Tasmanian coastal waters, have been demonstrated to exhibit selective antibacterial activity. The four species showed gradations in fouling by encrusting organisms and differential surface bacterial numbers. The two chemically defended species Amathia wilsoni and Orthoscuticella ventricosa had the most active antibacterial extracts and the lowest levels of fouling. In contrast, extracts of Cellaria pilosa and Bugularia dissimilis, which have no known secondary metabolites, had weak antibacteria properties, and colonies showed large numbers of encrusting fouling organisms. Counts of bacteria over the surfaces of the four species revealed that 0. ventricosa had the lowest numbers; B. dissimilis and C. pilosa had higher numbers while A. wilsoni had the highest counts, but the most patchy distribution.