sail-world.com
 
 
News Home Cruising Photo Gallery Video Gallery

 

Sail-World.com : Weed-eating fish 'key to reef survival'

Weed-eating fish 'key to reef survival'

'Algae and Porites'    ARC Centre of Excellence Coral Reef Studies ©    Click Here to view large photo

Preserving an intact population of weed-eating fish may be vital to saving the world’s coral reefs from being engulfed by weed as human and climate impacts grow.

A new study by researchers at the ARC Centre of Excellence for Coral Reef Studies has found weed-eaters like parrotfish and surgeonfish can only keep coral reefs clear of weed up to a point. After the weeds reach a certain density, they take over entirely and the coral is lost.

For some years researchers have pinned their hopes on the ability of weed-eating fish to keep the weeds at bay while the corals recover following a major setback like bleaching, a dump of sediment from the land, or a violent cyclone.

However the latest work by Dr Andrew Hoey and Professor David Bellwood at CoECRS and James Cook University shows that once the weeds reach a certain density, the fish no longer control them, and prefer to graze less weedy areas. 'As a result, the whole system tips from being coral-dominated to weed-dominated,' Andrew says.

'And our work shows that it doesn’t take a very high density of the fleshy seaweeds like Sargassum to discourage the fish, a patch of weed the size of a back garden could be enough to trigger a change. The fishes show a clear preference for grazing more open areas.'

Coral reefs are in decline worldwide, with many of them – especially in the Asia-Pacific region – showing ‘phase shifts’ from being coral-dominated to degraded states dominated by large fleshy seaweeds.

'In countries where people harvest the weed-eating fishes with spearguns, nets and so on, like Fiji, we are seeing a fundamental change in the nature of reefs from coral to weeds,' Andrew says. 'In Australia where there is much less harvesting of herbivorous fishes, the corals are in better shape and bounce back more readily from setbacks.'

The new insight into how well or poorly fish control weeds was gained by transplanting different densities of sargassum weed on a reef off Orpheus Island – and then using remote video cameras to record what the fish did.

'My wife and I must have watched hours and hours of video of fish feeding on weeds and counting the number of bites they took. It’s one of the less glamorous aspects of doing marine science,' he admits with a laugh.
In all they counted 28 species of fish taking 70,685 separate bites of weed and removing an average of 10 kilos of weed a day. In the more open areas this was enough to control the weed.

But Andrew also noticed the fish avoided the densely-weeded areas, perhaps for fear of predators lurking in the weed or because mature weeds are less palatable.

'This suggested to us there is a critical weed density, beyond which fish no longer control the weeds and they then take over the reef system. This in turn implies a need to keep the herbivore population as healthy as possible to avoid the reef reaching that tipping point.'

Fortunately, in Australia’s Great Barrier Reef Marine Park the harvesting of herbivorous fish is limited to a few recreational fishers. However Andy says it is his view that herbivorous fish ought to be carefully protected in order to give the Reef’s corals their best chance of making a rapid recovery from impacts like mass bleaching, the mud dumped by recent floods, and cyclones like Yasi.

'We should also bear in mind that this study was conducted in an area of the Great Barrier Reef Marine Park that has been protected from all commercial and recreational fishing for over 20 years and so is likely to have intact fish communities.

'How herbivores respond in areas of the world where they are still heavily fished may be absolutely critical to the survival of large areas of reef in Asia and the Pacific – and hence to the human communities who depend on them for food, tourism and other resources.'

Collecting weed -  ARC Centre of?nid=81217 Excellence Coral Reef Studies ©   Click Here to view large photo

Weed and diver inshore Great Barrier Reef -  ARC Centre of?nid=81217 Excellence Coral Reef Studies ©   Click Here to view large photo

Weed and diver inshore Great Barrier Reef -  ARC Centre of?nid=81217 Excellence Coral Reef Studies ©   Click Here to view large photo

ARC Centre of Excellence for Coral Reef Studies website




by ARC Centre of Excellence for Coral Reef Studies

  

Click on the FB Like link to post this story to your FB wall

http://www.sail-world.com/index.cfm?nid=81217

11:09 AM Thu 10 Mar 2011 GMT






Click here for printer friendly version
Click here to send us feedback or comments about this story.


News - USA and the World

ISAF Sailing World Championships - Watch medal races live here by Dan Ibsen, Sail-World Europe & UK editor,












ISAF Sailing Worlds, Santander - Strong competition for RS:X fleets by Olga Maslivets, International RS:X Class Assoc.,






































470 Men and Women Worlds - Game on for Olympic Qualification by 470 International Association Class,












A complete recap of the most successful Melges 20 World Championship by International Audi Melges 20 Class Association,




ISAF Santander - Upwards path for Austrian women's 470 crew + video
18ft skiffs: Carnage compilation from the glory days of the Grand Prix
ISAF Worlds: Video from the British Sailing Team
Bart's Bash expected to set new records this weekend
PWA Cold Hawaii World Cup - Marcilio Browne wins Super Session
470 Men and Women World Championships - Racing abandoned on day 2
ISAF Sailing World Championships - Day 4 images from Santander
ISAF Sailing Worlds, Santander: Emerging Nations Program sailors shine
ISAF Sailing Worlds, Santander - Teasing winds play havoc on day 4
ISAF Sailing World Championships: Hot conditions in Santander on day 4
Santander ISAF Sailing World Championships joins Bart’s Bash
PWA Cold Hawaii World Cup - Grounded fishing boat creates problems
Marseille One Design - GC32 Armin Strom Sailing Team emerge victorious
Rolex Big Boat Series 2014 - Ready for another 50 years
2014 Rolex Big Boat Series - Farr 40 Day 4
2014 Rolex Swan Cup - Eleventh-hour victories
Extreme Sailing Series - Kiwis clinch Act win in Istanbul + Video
2014 Rolex Big Boat Series - Two long races today for the J70 fleet
2014 Rolex Big Boat Series - Impressive to sail out of the Golden Gate
Extreme Sailing Series - Istanbul delivers four days of great racing
ISAF Sailing Worlds Santander - Day 3 images by Sail-World.com   
Extreme Sailing Series: Emirates Team NZ bounces back for series win   
Santander 2014 ISAF Worlds - Light winds and current test six classes   
ISAF Sailing World Championships - Solid Day 3 for US Sailing Team   
ISAF Sailing World Championships - Day 3 images by Jesus Renedo   
Marseille One Design 2014 - GC32 Armin Strom blitzes final day   
Volvo Ocean Race 2014-15 - Una Etapa 0 complicada para todos   
Santander 49ers: Olympic Gold Medallist says two into 90 does not go!! *Feature   
GBR aiming for first ever Nacra 17 Games berth at Santander Worlds   
Volvo Ocean Race: Man and sail overboard as Leg 0 serves up drama   
ISAF Sailing World Championships Santander 2014 – Images by Dan Ibsen   
Santander Worlds – already a spectator success   
ISAF Sailing World Championships Santander 2014 - Day 3 morning report   
Volvo Ocean Race 2014-15 - Tales from the extreme   
Volvo Ocean Race: Latest starter wins opening race   
2014 J/70 World Championship - Healy, Abdullah, Becker and Borges win   
2014 Rolex Big Boat Series - Full-blown, once again   
ISAF Worlds - Americans jump up Laser and Laser Radial leaderboard   
2014 Rolex Big Boat Series - Farr 40 Day 3   
ISAF Sailing World Championships - Day 2 images from Sail-World.com   


For this week's complete news stories select    Last 7 Days
   Search All News
For last month's complete news stories select    Last 30 Days
   Archive News







Sail-World.com  


















Switch Default Region to:

Social Media

Asia

Australia

Canada

Europe

New Zealand

United Kingdom


http://www.sail-world.com/event_images/image/Twitter_logo_small.png http://www.sail-world.com/event_images/image/FaceBook-icon.png  http://www.sail-world.com/event_images/image/RSS-Icon.png

United States

Cruising Northern

Cruising Southern

MarineBusiness World

PowerBoat World

FishingBoating World

 

Contact

Commercial

News

Search

Contact Us

Advertisers Information

Submit news/events

Search Stories/Text

Feedback

Advertisers Directory

Newsletter Archive

Photo Gallery

 

Banner Advertising Details

Newsletter Subscribe

Video Gallery

Policies

 

 

 

Privacy Policy

 

 


Cookie Policy

 

 



This site and its contents are © Copyright TetraMedia and/or the original author, photographer etc. All Rights Reserved.  Photographs are copyright by law.  If you wish to use or buy a photograph contact the photographer directly.
XLXL WAS US
LocalAds   DE  ES  FR  IT