Hi All,
I’m just forwarding a comment from Tim Reid about krill and whale numbers (see
below). Tim is an Australian scientist who is currently working in South Africa
and is not currently subscribed to Birding-aus. Some of you may know Tim for
the seabird research he has conducted over many years, particularly in
Tasmanian waters.
Coincidentally, the same story was on Catalyst on ABC TV last night. The link
to this story is shown below:
Iron Whales: http://www.abc.net.au/catalyst/
The gist of the story is that phytoplankton on the ocean surface take up carbon
dioxide from the atmosphere, but need iron to do this. However, there is a
shortage of iron on the surface of the Southern Ocean. Individual phytoplankton
gradually sink to the lower depths of the ocean, krill feed on them and bring
the iron that was stored in the phytoplankton back to the ocean surface. Baleen
whales feed on the krill. Therefore, iron is concentrated further up the food
chain, i.e. phytoplankton to krill to whales. The whales in turn poo out a lot
of the iron which is returned to the ocean surface. The next stage of the
research is to establish whether or not the phytoplankton can utilise the iron
that is pooed out by the whales.
So contrary to claims on Birdng-aus yesterday, more whales potentially means
more phytoplankton, which potentially means more (not less) krill. More
phytoplankton also means that more carbon dioxide can be absorbed from the
atmosphere, which could in turn slow down global warming. I can’t remember the
exact figure, but I think the Catalyst story said that ocean phytoplankton is
responsible for about one quarter of all atmospheric carbon dioxide taken up by
the earth’s vegetation. But don’t quote me on that figure, I’d have to look at
the story again.
Regards,
Stephen Ambrose
Ryde NSW
On Thu 14/04/11 9:58 PM , "Timothy Reid" <> wrote:
Hi Stephen,
I'm not on Birding-Aus (don't want to fill my inbox), but do read the archives.
A paper of interest with regards krill numbers in the antarctic is linked below.
Basically suggests that krill numbers are low these days because whale numbers
are low, with their poo fertilising the sea (think of some of the ideas to
overcome climate change by adding iron to the sea). Whale poo is high in iron
and where likely to fertilise the oceans, krill is also high in iron and so
needs there being a lot there.
Not that I should be thinking about such things (I'm living in Cape Town at the
moment).
Hope you’re well!
tim.
http://onlinelibrary.wiley.com/doi/10.1111/j.1467-2979.2010.00356.x/pdf
------------
Dr Tim Reid
Percy FitzPatrick Institute of African Ornithology
DST/NRF Centre of Excellence
Private Bag X3
University of Cape Town
Rondebosch 7701
Cape Town, South Africa
Web site: <http://www.fitzpatrick.uct.ac.za/> http://www.fitzpatrick.uct.ac.za/
Phone: (+27) (0) 21 650 3619
Fax: (+27) (0) 21 650 3295
Cell: (+27) (0) 83 3991 9165
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