Recolonisation of Acropora hyacinthus following climate-induced coral bleaching on the Great Barrier Reef

Abstract

Given projected increases in the frequency and/or severity of climatic disturbances, the persistence of corals may be more a function of their capacity for regeneration than resistance to such episodic disturbances. If so, climate change may favour those corals that regenerate fastest following acute disturbance. The tabular coral Acropora hyacinthus is fast-growing and typically dominates shallow wave-exposed habitats on the Great Barrier Reef, but it is extremely vulnerable to climate-induced coral bleaching and other disturbances (e.g. cyclones and outbreaks of crown-of-thorns starfish). The present study explores temporal changes in percentage cover and size structure of A. hyacinthus on reefs affected by the 2001−2002 bleaching event. Annual surveys conducted at 3 mid-shelf reefs from 2008 to 2010 revealed rapid, but very patchy, recovery of A. hyacinthus. Following extensive coral loss, local cover of A. hyacinthus increased due to growth of established colonies as well as addition and subsequent growth of new colonies. At one reef, recovery was mostly due to increased abundance of small colonies, assumed to have recruited since the bleaching, whereas recovery at the 2 other study reefs (<5 km away) was the sustained growth of established colonies. These results show that resilience of A. hyacinthus populations may be due to either recolonisation or ­persistence, but that, either way, these corals are well suited to rapid recovery following acute ­disturbance.