The study, which applied cutting-edge analyses designed by the JCU researchers to and data from the Australian Institute of Marine Science's 15-years of surveys across the Great Barrier Reef, found that protection was provided by having a diversity of fish that perform a similar function chomping down seaweed because different fishes respond differently to different pressures.
"There are three main groups of herbivorous fishes: territorial grazers that bite at the algae and are site-attached and actively defend a small patch of reef, roving grazers that feed in the same way but move around the reefs, and scrapers who range widely and feed by biting the algae back to the limestone surface of the reef, making clear patches where corals can establish. All are critically important," says study co-author Dr Hugh Sweatman, a Senior Research Scientist at the Australian Institute of Marine Science.
"These groups all play a similar role in keeping weeds in check, but each type responds differently to environmental fluctuations."
"In this research, we measured how strong the 'portfolio effect' was in different reef locations. We found that high biodiversity makes seaweed control twice as stable as it would be if we relied on one super-abundant species, like the sea urchin in the Caribbean," says Prof. Connolly.
"Biodiversity reduces the risk that environmental fluctuations will push overall herbivory below the threshold that might trigger a regime shift towards seaweed-dominated reefs."
The finding highlights the importance of maintaining biodiversity in the coral ecosystem, the researchers say.
"The more diversity you have, the lower the risk that all the fish that play a particular role on the reef like controlling seaweeds will crash at the same time. This is greatly
|Contact: Sean Connolly|
ARC Centre of Excellence in Coral Reef Studies