Resistance, survival and recovery of trampled corals on the Great Barrier Reef

Abstract

We investigated characteristics of coral colonies which determine the impact of human trampling on coral reef communities occurring as a result of tourists ‘reef walking’. These characteristics are: resistance or vulnerability to physical damage; survival after damage; and recovery after damage. Four species, common to the Great Barrier Reef, Australia, were chosen for the study—three branching corals, Acropora palifera, Acropora millepora, and Pocillopora damicornis; and one massive coral, Porites lutea. Laboratory trials demonstrated that the branches of Acropora palifera were most resistant to breaking, and those of Acropora millepora were least resistant. In a field experiment, trampling did not damage the massive skelton of Porites lutea, but did destroy a proportion of the living tissue. The colonies of all species were highly and equally tolerant to damage in field experiments. However, the survival of detached fragments differed between the three branching species; that of Acropora millepora fragments was higherst, and that of Pocillopora damicornis fragments was lowest. Survival of fragments was also dependent on size. The recovery of damaged colonies and fragments also differed between species. Overall, Acropora millepora had the highest recovery rate, and Acropora palifera and Porites lutea the lowest.