Extinction risk not the answer for reef futures

November 17, 2014, ARC Centre of Excellence in Coral Reef Studies
Giant humphead parrotfish: a species not regarded at risk of extinction, but one which has suffered severe decline. Credit: Image: JP Krajewski

Leading coral reef scientists in Australia and the USA say there needs to be a new approach to protecting the future of marine ecosystems, with a shift away from the current focus on extinction threat.

"Extinction is the final endpoint, but coral reefs are in deep trouble long before we get to that point. We need to take action much earlier," says Professor David Bellwood from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University.

"The goal should be to maintain reefs that can support corals, fish and humans" Professor Bellwood says.

In a world first study published in the journal, Current Biology, researchers tested the concept of 'double jeopardy', which is widely used to assess . It is based on the assumption that the risk of is greater if a species has both a small geographic range and low numbers.

The researchers counted the numbers of individuals of more than 400 species of fishes and corals across a 10,000km swath of the Pacific Ocean, from Indonesia to French Polynesia.

Professor Terry Hughes from the Coral CoE says they found no relationship between each species abundance' and its geographic range. To the contrary, the researchers found that some species with a small range had large numbers while some with a vast range spanning the Indo-Pacific Ocean were quite rare. The widely held assumption of double jeopardy is false.

"Our findings call into question the growing practice of assessing extinction risk of coral reef species without knowing how many of them are out there," says Professor Hughes. This is the first study to systematically count corals and reef fishes at a geographic scale".

The researchers argue that coral reef systems are threatened long before individual species are in danger of extinction. They say extinction threat is a poor approach to take to ensure the future of coral reefs.

"Many species on coral reefs are critically important for maintaining ecosystem health. Many reefs are in serious decline, even if the chances of individual species going extinct are slim."

Professors Bellwood and Hughes argue that the criteria for the IUCN threatened species Red List, used to assess extinction threat, are inappropriate for widespread marine species.

"The vast majority of marine plants and animals are comparatively resistant to global extinction because of their high rates of reproduction, ability to disperse widely, and huge geographic ranges which span up to tens of millions of square kilometres," Professor Hughes says.

"Rather than guessing at which species are threatened, we need a focus on local action to avert or recoup the loss of ecosystem function caused by habitat destruction and severe depletion of key species," Professor Hughes says.

Professor Bellwood says "This paper calls for caution when identifying species at risk of extinction on . It highlights the potential weaknesses in current approaches and offers an alternative approach where are valued for the services they provide for both reefs and humans".

Explore further: Specialized species critical for reefs

More information: Double Jeopardy and Global Extinction Risk in Corals and Reef Fish by Terry P. Hughes, David R. Bellwood, Sean R. Connolly, Howard V. Cornell and Ronald H. Karlson is published in the journal, Current Biology (2014), dx.doi.org/10.1016/j.cub.2014.10.037

Related Stories

Specialized species critical for reefs

September 15, 2014

One of Australia's leading coral reef ecologists fears that reef biodiversity may not provide the level of insurance for ecosystem survival that we once thought.

Sharks more abundant on healthy coral reefs

September 10, 2014

Sharks in no-fishing zones in the Great Barrier Reef (GBR) Marine Park are more abundant when the coral is healthy, according to a study published September 10, 2014 in the open-access journal PLOS ONE by Mario Espinoza from ...

Recommended for you

Fish-inspired material changes color using nanocolumns

March 20, 2019

Inspired by the flashing colors of the neon tetra fish, researchers have developed a technique for changing the color of a material by manipulating the orientation of nanostructured columns in the material.

Researchers shed new light on the origins of modern humans

March 20, 2019

Researchers from the University of Huddersfield, with colleagues from the University of Cambridge and the University of Minho in Braga, have been using a genetic approach to tackle one of the most intractable questions of ...

One transistor for all purposes

March 20, 2019

In mobiles, fridges, planes – transistors are everywhere. But they often operate only within a restricted current range. LMU physicists have now developed an organic transistor that functions perfectly under both low and ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.