Deep refuges 'can help save our reefs'

May 30, 2013

(Phys.org) —Marine scientists from Australia and the USA today called for global efforts to protect deeper coral reefs as insurance against the widespread destruction of shallow reefs and their fish stocks now taking place around the world.

In the journal Nature Climate Change, lead author Dr. Tom Bridge from the ARC Centre of Excellence for Coral and colleagues point out that policies have so far failed to prevent the widespread destruction of coral reefs and their fish life, which now threatens the food security of millions of people.

With more than 60 per cent of the world's reefs under immediate threat from human activity, the researchers argue that efforts to identify and protect reefs lying 30-150 metres below the surface should be stepped up, so as to provide a secure refuge for fish and corals that can also live on deeper reefs.

These deeper reefs are relatively insulated from global warming and other direct human pressures for the time being – but there are signs that overfishing, pollution and other forms of degradation are now starting to affect them too, making their protection urgent, they warn.

"We recommend acting quickly, because pressure to over-exploit deep reefs will inevitably grow as shallow reefs become almost universally degraded due to growing human and climate change," says co-author Dr. John Guinotte from the Marine Conservation Institute.

"In China, coastal development and overfishing has destroyed 80% of coral cover in just the past 30 years. In Australia, coral cover on coastal reefs is also plummeting and the World Heritage Listing of the (GBR) is now under review."

Many reef species which inhabit shallow waters are also to be found on reefs at depths of 30 metres or more, amid lower light conditions. This makes these deep reefs a potential refuge for both corals and other sea life when shallow reefs are degraded.

However, worldwide there is only a patchy record of where these deeper reefs are located, making their protection problematic.

"The area of these deep reefs may in fact be quite large. On the GBR recent surveys have revealed up to 20,000 square kilometres of deep reef – equal in size to the combined area of all the shallow reefs," Dr. Bridge says.

"While many species inhabit both shallow and deeper waters, the extent to which this occurs is as yet poorly understood. However they may form an important source of replenishment for shallow reefs and their , given the destruction that is occurring on these reefs themselves and in the surrounding mangroves and sea-grass beds which are a nursery for juvenile fish."

At present very few of these deeper reef systems receive any form of protection around the world because reef management – where it exists – tends to focus on shallow reefs, the scientists say. Mid-level and deeper reefs are not generally included in Marine Protected Areas – an oversight that needs to be amended.

"Adopting a broader ecosystem-scale approach that incorporates deep reefs around the world would have multiple and long-term social and economic benefits.

The economic and conservation value of deeper reefs renders them worthy of protection in their own right, and safeguarding these habitats will also extend ongoing efforts in shallow water to protect reef species across their entire depth range."

Their article "The need to protect all " by Tom C.L. Bridge, Terry P. Hughes, John M. Guinotte and Pim Bongaerts appears in the journal Nature Climate Change.

Explore further: Hopes, fears, doubts surround Cuba's oil future

add to favorites email to friend print save as pdf

Related Stories

Exploring Bonaire's deep reef by submarine

May 29, 2013

In a submarine, IMARES Wageningen UR researchers Erik Meesters en Lisa Becking will explore the deep reef of Bonaire, an island in the Dutch Caribbean. They aim to map the biodiversity of their research location, ...

Sea of the living dead

Sep 26, 2012

(Phys.org)—The world's coral reefs have become a zombie ecosystem, neither dead nor truly alive, and are on a trajectory to collapse within a human generation according to an academic from The Australian ...

Remote reefs can be tougher than they look

Apr 04, 2013

(Phys.org) —Isolated coral reefs can recover from catastrophic damage as effectively as those with nearby undisturbed neighbours, a long-term study by marine biologists from the Australian Institute of Marine ...

Recommended for you

Hopes, fears, doubts surround Cuba's oil future

13 hours ago

One of the most prolific oil and gas basins on the planet sits just off Cuba's northwest coast, and the thaw in relations with the United States is giving rise to hopes that Cuba can now get in on the action.

New challenges for ocean acidification research

Dec 19, 2014

Over the past decade, ocean acidification has received growing recognition not only in the scientific area. Decision-makers, stakeholders, and the general public are becoming increasingly aware of "the other carbon dioxide ...

Compromises lead to climate change deal

Dec 19, 2014

Earlier this month, delegates from the various states that make up the UN met in Lima, Peru, to agree on a framework for the Climate Change Conference that is scheduled to take place in Paris next year. For ...

User comments : 0

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.