Scleractinian Coral Communities of Two Inshore High Island Fringing Reefs at Magnetic Island, North Queensland

Abstract

The characteristics of the scleractinian coral communities on 2 fringing reefs of an inshore high island were compared, using data from surveys by the line transect method. The communities are divided into zones on the basis of numbers of species per transect, species diversity indices, percentage coral cover and numerical classification of transects. The Geoffrey Bay community is divided into a Reef Flat Zone dominated by Goniastrea aspera, Platygyra sinensis and Montipora ramosa and a Reef Slope Zone dominated by arborescent and tabulate Acropora species. The Cockle Bay community is divided into an Inner Reef Flat Zone dominated by Montipora rarnosa, an Outer Reef Flat Zone dominated by Platygyra sinensisand Symphyllia recta, and a Reef Slope Zone dominated by Goniopora tenuidens. Differences in community structure, species composition and distributions of abundant species of the zones of the 2 reefs, can be attributed to prevailing environmental conditions. In particular, differences in exposure to wave action and sedimentation between the reefs are reflected in smaller numbers of species, lower coral cover, lower values of the Shannon Diversity Index and selection of silt resistant species on the less exposed reef in Cockle Bay.