EFFECTS OF SUBSTRATUM ON THE RECRUITMENT AND DEVELOPMENT OF AN INTERTIDAL ESTUARINE FOULING ASSEMBLAGE

The effect of four substrata (concrete, plywood, fibreglass and alumin ium) on the recruitment of species and development of an intertidal es tuarine fouling assemblage was examined in Quibray Bay of Botany Bay, New South Wales, Australia. Many species, including the oyster Saccost rea commercialis (Iredale & Roughley) and the barnacles Hexaminius sp. , Balanus amphitrite Darwin and Balanus variegatus Darwin, recruited i n greater numbers on concrete or plywood surfaces than on fibreglass o r aluminium. As a result, patterns of change in the number of species through time were dependent on the substratum. Multivariate analyses i ndicated that assemblages on different substrata were significantly di fferent after 1 or 2 months of submersion, but became more similar aft er longer periods (up to 4-5 months). The reasons for this gradual con formity varied depending on the season of submersion and the compositi on of the species settling in a particular season. The results of this study indicated that the nature of the substratum can affect both ini tial colonisation of particular species and the development of the ass emblage over time. Because the effect of substratum varies with the pe riod of submersion, comparisons of various studies on fouling assembla ges using different natural and artificial substrata and for varying l engths of time are likely to be very difficult.