> Powerboat-World.com
 
 
News Home Video Gallery Newsletters Features FishingBoating MarineBusiness-World Sail-World Australia Australian Cruising
Photo Gallery

 

Sail-World.com : Seabed-feeding krill return iron to Southern Ocean surface waters

Seabed-feeding krill return iron to Southern Ocean surface waters

'A swarm of Antarctic krill - Euphausia superba (Photo: Steve Nicol)'    Australian Antarctic Division ©

Antarctic krill is a species thought to live in the upper ocean, but it has now been shown that a large part of the adult population regularly migrates down to the seabed to feed.

They return with stomachs containing large quantities of iron, a scarce nutrient that helps to promote algal growth in the near-surface waters.

Reporting this week in the Journal Limnology and Oceanography, researchers from the Australian Antarctic Division, The British Antarctic Survey, Southampton University and Oslo University report a startling new role for krill in the Southern Ocean food web.

The textbook picture is that krill are a species of the surface waters. These new findings show that they also migrate regularly down to the seabed to feed on settled detritus.

This detritus diet is also rich in iron - a scarce micro-nutrient that can limit plant growth in approximately 40% of the World Ocean. The huge biomass of krill and their regular commutes between surface and seabed means that krill could help fertilise the anaemic surface waters.

'It was already known that krill can visit the seafloor to feed, even to depths over 3 km, but these observations were always treated as exceptions,' said lead author Katrin Schmidt from the British Antarctic Survey.

'What surprised us was how common these seafloor visits were – we found that around 20% of the population could be migrating at any one time.'

The implications are profound. The biomass of krill is similar to that of the human population, so their visits to the seabed mean the exchange of a huge biomass between two fundamentally different food webs.

For example, this exchange is important for the carbon cycle, as krill stomachs contain large quantities of iron after seabed visits. Krill have recently been suggested to be important in the iron cycle, but this role was in recycling iron that was already there in the surface waters.

'Our findings suggest a fundamentally different role in re-supplying the iron that has been lost from the surface layers within settling particles. While recycling is important, it is these re-supply processes that stimulate plant growth and the drawdown of atmospheric carbon dioxide,' Dr Schmidt said.

Australian Antarctic Division krill biologist Steve Nicol said these findings are also significant because it shows krill are found throughout the ocean water column, not just at the surface.

'All estimations of krill distribution and abundance are a result of sampling the top 200 metres of the ocean, either using nets or echosounders,' Dr Steve Nicol said.

'If a large portion of the krill population lives, or migrates to, waters deeper than 200 metres then we have been missing them completely.

'As the krill fishery is the largest in Antarctic waters it is vitally important that we are able to adequately sample the population so that we can set sustainable catch levels and interpret the changes that we see in terms of other features in the environment,' he said.

The benthic habitat where krill are feeding - about 177 m depth at latitude -66.7576 and longitude 143.2862. (Photo: AAD) -  Australian Antarctic Division?nid=85868_©  

Antarctic Krill (Photo: Steve Brookes) -  Australian Antarctic Division?nid=85868_©  

Australian Antarctic Division website




by Australian Antarctic Division

  

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

http://www.powerboat-world.com/index.cfm?nid=85868

10:44 AM Wed 13 Jul 2011 GMT






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


Power Boat News



Pontoon Boats are a hit with families and entertainers by Sanctuary Cove International Boat Show,










Glacier Bay returns to Australia, re-launching at SCIBS by Sanctuary Cove International Boat Show,








Singapore Yacht Show 2014. Boats to make your eyes pop. by Guy Nowell, Sail-World Asia, Singapore










Power to the people at Sanctuary Cove International Boat Show by Sanctuary Cove International Boat Show,


SCIBS VIP lounge back bigger and better in 2014 by Sanctuary Cove International Boat Show,




Singapore Yacht Show 2014. And another thing… by Guy Nowell, Sail-World Asia, Singapore






























RYA Competent Crew Skills – Second edition now available
Mondo Marine invests in Chinese shipyard
Aqualuma partners with ASMEX 2014 for Welcome function
Kaohsiung to welcome the world for 1st Taiwan International Boat Show *Feature
Changed boating conditions for ski race on Clarence River
Royal Victoria Cup - Cable, Hockney and Shipley victorious
Channel 7 stage returns to Sanctuary Cove International Boat Show
Hainan Rendezvous: suffering from a hangover?
Palm Beach International Boat Show shows healthy attendance
Brisbane Tinnie & Tackle Show - this weekend!
Coastal infrastructure and species loss - Climate Change consequences *Feature
rescueME PLB1 – safety assured in one compact, light package *Feature
Japan's Antarctic whaling program harpooned
All Marine Spares hits the boat show trail in a trailer *Feature
Royal Victoria Cup to take place this weekend
Rowers and ferry masters encouraged to share waterways safely
Go crazy about whales in a special family fun day at the museum
New generation trawler boats - tradition with a twist
Arvor releases new Sportsfish range
AIMEX focuses on commercial show in Asia
Further Australian growth for Stabicraft   
Southport Yacht Club will host a free 'Discover Sailing Day'   
Melbourne Boat Show earlier this year - 12 to 16 June   
FinScan digital switching fitted to new rescue vessels   
Kids' Zone a drawcard at Brisbane Tinnie & Tackle Show   
Brisbane Tinnie & Tackle welcomes Engel as stage sponsor   
BIAV appoints new GM   
Trash to Treasure - A seafood story   
Amazing Whales – Evolution and survival opens tomorrow   
Maritime Alert - Dangerous conditions forecast for NSW boaters   
PWC riders brave South Island waters raise $93,000 for melanoma fight   
Solar1 Monte Carlo Cup to take place this July   
12 weeks til Melbourne Boat Show   
First deadline for SCIBS exhibitors looms March 24   
Paul Burt, boating guru, is the face of Sanctuary Cove Boat Show   
Marine Industry loses a loyal servant: Vale Gunter Bruckner   
Positive pass mark for new venue   
Couran Cove signs lease deal with Hope Island Marina   
Phones outpace PCs and TV as preferred device   
UIM Awards Giving Gala - Stefano Casiraghi Memorial Trophy for RYA   


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/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 NEW PBW