Parrotfishes a key to reef stability | Practical Fishkeeping magazine

http://www.practicalfishkeeping.co.uk/pfk/pages/item.php?news=1444 --- New research has revealed that parrotfish may be the key to maintaining the stability of coral reef habitats and preventing them from transforming into a stable macroalgal-dominated condition following disturbance.  The results are published in the most recent issue of the journal Nature by Peter Mumby, Alan Hastings and Helen Edwards.  The authors used a simulation model to predict the effects of various perturbations to the system, including the effects of hurricanes, as well as the removal of herbivorous sea urchin on coral cover and macroalgal abundance on the complex forereef habitats of the Caribbean.  Macroalgae (seaweed) proliferate if dead coral is not sufficiently grazed and are capable of either arresting coral growth or overgrowing living coral.  The authors found that the macroalgae-dominated community is an alternative stable state of the ecosystem and one that is not readily reversible.