Systematics and ecology of the sponges of Motupore Island, Papua New Guinea

Abstract

Taxonomic descriptions of twenty five of the most common Motupore Island reef sponges are given together with a discussion of their zoogeographic affinities in relation to particularly, northern Australia, Indo Malaya and the West Central Pacific. The distribution and abundance of these prominent sponges in addition to a further thirty two species which occur on the Motupore Island reef is described. Physical and biotic features are shown to have a significant role in determining the distribution of these species on the reef. Variation in physical oceanographic parameters between reef biotopes can be related to the distribution of particular groups of sponge species. The reproductive cycle and life history of Spirastrella vagabunda was studied in an attempt to determine the influence of reproductive mode on the distribution of this species in a shallow reef rubble zone. The development of a sexually derived larva capable of boring dead coral substrate and fragments generated by predatory activity combined with consistent bi-directional current and wave activity are shown to contribute to this species' unique disperal patterns and general success in the shallow reef environment.