The observations were documented through underwater videocams, in schools of up to 15 fish, grazing the crest, slopes and outer flats of the reef, and chomping away at more than ten times the rate of other weed-eaters. However the team noticed that the Rabbitfish concentrated their weed-removal efforts on the crest of the reef and were less effective on the slopes and flats – a feeding preference that is yet to be explained. In a previous study, an overgrown reef had been cleaned up by another unexpected intruder, a striped batfish.
Rebecca explained that the recovery of damaged reefs may depend on several different ‘guilds’ of fishes, with different feeding preferences, that will focus on particular parts of the reef and stages of the weed infestation. For such an approach to work, all the various species have to be kept intact in the reef environment, ready to play their part in a salvage operation when it becomes necessary. In Australia these herbivore fish populations are still in fairly good shape, but around the world as the big predators are fished out, local communities are targetting the herbivores. In Malaysia,
Thailand, Hawaii, Indonesia, Micronesia and French Polynesia there are reports of serious declines in herbivore numbers of up to 90 per cent.
“By eliminating rabbitfishes, we may be unwittingly eliminating the very thing which enables coral reefs to recover from the devastation which human activity imp-exposes them to.” Prof. Bellwood says that one of the lessons from the video study is that obscure rabbitfish species may play a critical role in the play a critical role in the survival and maintenance of coral ecosystems, and should not be overlooked. They are a key part of the resilience of the whole reef system. “On land the rabbit is a major headache, but in the sea the rabbitfish may be an important factor in helping to keep the world’s number one tourist attraction in good shape,” he says.
Rabbitfishes grow to about 40 cm and have small, rabbit-like mouths, large dark eyes, and a shy temperament which gives them their family name Siganidae. There are 28 species in a single genus, Siganu. Some of the species are adorned with prominent face stripes thus colloquially called Fox faces.
Reference: Fox R.J. and D.R. Bellwood (2008)