Drift Seeds and Fruit on Raine Island, Northern Great Barrier Reef, Australia

Abstract

The vegetation of Raine Island, a sand cay of the fied with some certainty. Sixteen species included viable northern Great Barrier Reef and the drift seeds and fruit on individuals. On a percentage basis the highest level of its beach and along its strand-line were studied during July- viability was in Leguminosae, Convolvulaceae and Pan- August 1987. Seeds and fruit were identified and tested for danaceae. The only drift seed of a species present as living viability by germination following scarification or using plants on the island was Ipomoea macrantha. tetrazolium. Most drift seed and fruit were from species common to A total of twelve species of vascular plant was found both Papua New Guinea and northern Australia. However, growing on the island. Ten of these had been noted on seeds of Pangium edule Reinw., not known to occur in previous expeditions; Ipomoea macrantha Roemer & Australia but occurring in Papua New Guinea, had presum- Schultes was last recorded in 1846. Dactyloctenium aegyp- ably floated the c. 300 km from that country. This hypo- tium (L.) Beauv. and Cleome viscosa L. are new records for thesis is supported by the existence of a southerly-flowing the island. Three distinct ecological niches were identified ocean current immediately to the east of the northern Great which differed in species composition. Barrier Reef. Seed/fruit density was 710 per 100 m beach length. Over-