Corals and coral Communities of Lord Howe Island.

Abstract

Fifty-seven species of 33 genera of hermatypic Scleractinia are found at Lord Howe Island, the southernmost coral reef of the Pacific. All except two undescribed species are known from the Great Barrier Reef. The families Fungiidae, Merulinidae, Caryophyllidae and Oculinidae are absent from the island and the Mussidae are represented by two genera only. Coral communities are mapped from survey data and aerial photography. Lagoon and reef communities defined using a polythetic agglomerative procedure are shown to have an ordered distribution relative to their hydrodynamic regime. These communities differ substantially from their tropical equivalents due to growth form deviations of dominant species and depauperate species composition. Available surface circulation and temperature data suggest existing coral communities are the result of a balance between periodic denudation by cold, subantarctic currents and recolonization by larvae from tropical currents. Low temperatures per se appear to have llttle effect on coral growth but may affect growth form responses to light regimes.