Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Wildlife Conservation Society study uncovers a predictable sequence toward coral reef collapse

29.09.2011
Research identifies 8 factors that can alert managers to the threat of overfishing in otherwise healthy-looking reefs

Coral reefs that have lots of corals and appear healthy may, in fact, be heading toward collapse, according to a study published by the Wildlife Conservation Society and other groups.

Using data from coral reef systems across the western Indian Ocean, an international team of researchers identified how overfishing creates a series of at least eight big changes on reefs that precipitate a final collapse. This information can help managers gauge the health of a reef and tell them when to restrict fishing in order to avoid a collapse of the ecosystem and fishery.

The study appears this week in the early online edition of the Proceedings of the National Academy of Sciences. The authors of the study include: Tim R. McClanahan and Nyawira A. Muthiga of the Wildlife Conservation Society; Nicholas A.J. Graham and Joshua E. Cinner of James Cook University, Queensland, Australia; M. Aaron MacNeil of the Australian Institute of Marine Science; J. Henrich Bruggemann of Laboratoire d'Ecologie Marine, Université de la Réunion, La Réunion, France; and Shaun K. Wilson of the Department of Environment and Conservation, Perth, Western Australia.

The authors say these changes are like a series of light switches, each of which make the reef more degraded and dims the chances of sustained fishery production and recovery.

"The study identifies eight changes before all of the ecological lights go off and the reef and fishery are gone" said Dr. McClanahan, the lead author on the study and the head of WCS's coral reef research and conservation program.

The study shows that in well-protected areas, there are typically 1000-1500 kilograms of reef fish of various species per hectare of coral reef. As the volume is fished down below 1000 kilograms, the early warning signs—like increased seaweed growth and urchin activity—begin to appear. The researchers found that between 300-600 kilograms per hectare, there appeared to be a "window" of what is known as maximum sustainable yield, but when the fish stock drops below 300 kilograms per hectare, the reef is in real trouble, they said.

"Below 300 kilograms per hectare we see a series of dramatic changes on reefs. This is where you get on a real slippery slope," McClanahan noted. "Strangely, the metric used by most managers to gauge the health of reef systems—coral cover—is the last threshold before ecosystem failure. Overfished reefs can appear healthy and then shift to algae dominated seascapes."

The authors recommend measuring the biomass of fish instead of coral cover to identify the early warning rather than the final sign of reef collapse.

"The good news is that a reef can likely provide sustainable fisheries even after the first three warning switches are turned off, but it becomes increasingly difficult to maintain a healthy fishery and restore reefs when the final five switches have been turned off," said Dr. McClanahan. "This study provides managers and policy makers with a tangible target of where to maintain their fishery."

Dr. Joshua Cinner from James Cook University in Australia added: "Of course, having a target is one thing, but achieving it is, well, another kettle of fish. So we also assessed how well different reef management schemes did at maintaining reefs."

Reef fisheries with no regulations tended to perform poorly, with some passing all the switches and completely collapsing. No-take marine reserves, where fishing was prohibited, were the best performers and tended to maintain key ecosystem processes such as predation.

"People depend on reefs for their livelihoods, so we can't prohibit fishing everywhere," noted Dr. Cinner. "A key finding from our study was that even easily enforceable regulations that restrict gear or the types of species that can be caught helped maintain biomass. These regulations are often more agreeable to fishermen than no-take closures and consequently receive higher levels of support and compliance."

"There is no one size fits all solution to save the world's coral reef ecosystems. To be politically and socially sustainable, tangible and objective management targets are critical to help managers make difficult near-term decisions of restricting or altering fishing practices for long-term social and ecological gain," said Dr. Caleb McClennen, Director of WCS's Marine Program. "This exhaustive research helps identify critical metrics and methods for sustainable management of coral reefs across the true gradient of ecological condition and management reality."

From Fiji to Kenya to Glover's Reef, Dr. McClanahan's research has been examining the ecology, fisheries, climate change effects, and management of coral reefs at key sites throughout the world. This work has been supported by the John D. and Catherine T. MacArthur Foundation and The Tiffany & Co. Foundation.

John Delaney | EurekAlert!
Further information:
http://www.wcs.org

More articles from Ecology, The Environment and Conservation:

nachricht Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

nachricht International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Electrical 'switch' in brain's capillary network monitors activity and controls blood flow

27.03.2017 | Health and Medicine

Clock stars: Astrocytes keep time for brain, behavior

27.03.2017 | Life Sciences

Sun's impact on climate change quantified for first time

27.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>