Stephen
It was an excellent segment on Catalyst. Almost spookily timely.
Carl Clifford
On 15/04/2011, at 9:52 AM, Stephen Ambrose wrote:
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”
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
