Reef Report for Wednesday, January 3, 2007
Reef Recovery from Disturbance Linked to Rare Species of Fish
A research team led by Dr. David Bellwood recently published the result of their research, which has shed new light on the recovery of coral reefs from disturbances.
For a long time itís been known that the damaged parts of coral reefs in the Indian and Pacific Ocean are very slow to recover if algae overgrow the dead coral skeletons.
The thick cloak of algae inhibits the ability of coral larvae to begin their growth cycle, as well as slow the growth of the few corals that do get started.
Prior to this research it was thought that a complex of algae-eating fish, including commonly found species like parrotfish and surgeonfish, aided in the recovery of algae-covered corals by reducing the algal cover through their feeding activities.
The research team investigated this process by combining some very simple research techniques with some very modern technology. The team consructed cages that excluded fish from small plots of reef, enabling a growth of algae to grow over the coral., Then they removed the cages, and placed underwater video cameras over the plots to record the species that visited the area and their behavior.
It turned out the a fairly uncommon species of fish, the long-finned batfish, (Platax pinnatus) was by far the most important species in reducing the algal cover, and that 43 other species of algal grazing fish played only a very minor role in the process. Oddly enough, the batfish was until this research thought to feed on invertebrates, as basic research on this fish had yet to be completed.
From an ecological standpoint, the results of this study were unexpected. Often times its thought that the ability of an ecosystem to recover from disturbance is strongest where the biodiversity (the number of species in an ecosystem) is highest. That was not the case here, as a single keystone species played the major role in reef recovery.
However, in highly diverse ecosystems the roles that each species play can become highly specialized, so itís not entirely unexpected that one species of fish may have evolved to specialize on feeding on algae growing in disturbed ecosystems. (Weíd like to think the a good reason that this species of batfish is uncommon is due to the small amount of disturbance that is occurring on coral reefs in Australia, but thatís purely speculation, and perhaps a topic for a bright and able marine research specialist in the future!)
News coverage of this story, from Daily India
A summary of this research project.
An interview with Dr. David Bellwood, team leader of the research project.
The weekly reef report is written by Joel Groberg of DiveTheReef.com,
who compiles them from the many conversations he has with dive staff in the area, as well as† many other local sources in the dive
Index of all reef reports.