Herbivorous reef fishes critical for long-term coral reef health and resilience

24 August 2009 | News story

Herbivorous reef fishes not only have a key role in keeping algal growth at bay and thereby enabling corals to grow and reproduce, they are also important players in the long-term health and survival of coral reefs in the face of climate change and other threats. These are the findings of a new report published by IUCN and its institutional partners released today.

The report, which focuses on the Asia-Pacific region, takes an in-depth look at the interaction between coral communities, algae and herbivorous reef fishes. It goes on to offer practical advice to coral managers on how to monitor the abundance, biomass and size structure of these important species.

In the perpetual battle for supremacy between coral and algae, herbivorous fishes are the linchpin working in favour of corals by limiting the establishment and growth of algal communities that impede coral recruitment. Each functional group studied by the report - including grazers, browsers, scrapers and excavators - play different but complementary roles in maintaining the resilience of coral reefs.

"Coral reef monitoring has traditionally focused on monitoring the status of coral communities and populations of conspicuous species, particularly fisheries species like fish and invertebrates." says report co-author Alison Green of The Nature Conservancy. "This provides useful information on the current status of coral reef communities and associated fisheries, but does not provide information on the status of key ecological processes that are essential for maintaining coral reef resilience."

Developing new metrics for monitoring coral reef resilience that are process oriented is an urgent priority for the improved management of coral reefs. This report presents a protocol for monitoring functional groups of herbivorous reef fishes, which play a critical role in coral reef resilience.

Under threat

With close to 500 million people in the world living within 100km of coral reefs - many of them living subsistence lifestyles - fishing pressure on herbivorous fishes can be intense. Overfishing of some of the larger species of herbivorous fish has led to worrying declines and, some species, for example humphead parrotfish, are now only common in remote areas or areas where fishing is prohibited.

"The good news is that herbivorous fishes can bounce back if given adequate protection." says David Obura, Chair of the IUCN Climate Change and Coral Reefs Marine Working Group. "Populations of herbivorous fishes tend to recover quickly after protection in no-take Marine Protected Areas. Evidence also suggests that coral reefs with low fishing pressure and relatively intact food webs provide greater resilience to threats such as climate change."

The report is the seventh in the series of Working Papers by the IUCN Resilience Science Group (see http://iucn.org/cccr/publications/). It was produced in partnership with The Nature Conservancy (TNC), the ARC Centre of Excellence for Coral Reef Studies and James Cook University.

For more information, please contact:
Dr Alison GREEN
Senior Marine Scientist, Tropical Marine Conservation Program
The Nature Conservancy, 51 Edmonstone Street, P.O. Box 772, Brisbane, Queensland 4102, Australia
Tel: +61 7 3214 6902
Email: agreen@tnc.org

Dr David OBURA
Coordinator
Coastal Oceans Research and Development - Indian Ocean
9 Kibaki Flats, Kenyatta Public Beach, Bamburi, PO Box 10135, Mombassa, 80101, Kenya
Tel: +254 41 548- 0117
Email: dobura@cordioea.org