Krill provide iron for Southern Ocean: study

Krill provide iron for Southern Ocean: study

http://fis.com/fis/worldnews/worldnews.asp?l=e&ndb=1&id=44144

An international team of researchers has found that Antarctic krill could be vital in the fertilization of the Southern Ocean with iron and thereby the stimulation of phytoplankton growth. This enrichment betters the ocean’s ability to store CO2.

The tiny shrimp-like crustacean is the staple diet for various fish, penguins, seals and whales, as well as being caught by commercial fisheries for human consumption by way of omega-3-rich krill oil and other products.

In findings published this month in the journal Limnology and Oceanography, researchers describe how Antarctic krill (Euphausia superba), instead of residing mostly in surface waters, regularly spend time on the sea floor feeding on iron-rich fragments of decaying organisms. The krill then swim back up to the surface of the ocean and release the iron from their stomachs and into the water.

"We are really excited to make this discovery because the textbooks state krill live mainly in surface waters,” said lead author from British Antarctic Survey Dr Katrin Schmidt.

“We knew they make occasional visits to the sea floor but these were always thought as exceptional. What surprises us is how common these visits are – up to 20 per cent of the population can be migrating up and down the water column at any one time," she noted.

The team of researchers dissected the stomach contents of more than 1,000 krill harvested from 10 Antarctic research expeditions and discovered that the krill caught near the surface contained high levels of iron-rich material from the seabed in their stomachs.

Plus, the scientists studied photographs of krill on the sea floor, acoustic data and net samples, all of which gave sturdy evidence that the crustaceans frequently feed at the bottom of the sea.

These recent findings have implications for managing commercial krill fisheries and can help better comprehend the natural carbon cycle in Antarctica’s Southern Ocean.

“The next steps are to look at exactly how this iron is released into the water," Schmidt added.

Antarctica’s krill fishery is expanding. It is managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR).

An estimated 100-500 million tonnes of krill -- similar to the weight of the world's human population -- roam in the Southern Ocean.

Whales and ocean iron fertilization

http://blogs.discovermagazine.com/discoblog/2010/04/23/a-novel-geoengineering-idea-increase-the-oceans-quotient-of-whale-poop/

A Novel Geoengineering Idea: Increase the Ocean’s Quotient of Whale Poop


The fight against global warming has a brand new weapon: whale poop.

Scientists from the Australian Antarctic Division have found that whale poop contains huge amounts of iron and when it is released into the waters, the iron-rich feces become food for phytoplankton. Phytoplankton absorbs carbon dioxide from the air, the algae is in turn eaten by Antarctic krill, and baleen whales eat the krill. Through this neat cycle, globe-warming CO2 is kept sequestered in the ocean.

Scientists have long known that iron is necessary to sustain phytoplankton growth in the oceans, which is why one geoengineering scheme calls for adding soluble iron to ocean waters to encourage the growth of carbon-trapping algae blooms. While environmentalists have fretted over the possible consequences of meddling with ocean chemistry that way, this new study on whale poop suggests an all-natural way to get the same carbon-trapping effect: Increase the number of whales in the ocean.

When Stephen Nicol of the Australian Antarctic Division analyzed the feces of baleen whales, he found an astounding amount of iron in it. New Scientist reports:

Nicol’s team analyzed 27 samples of faeces from four species of baleen whales. He found that on average whale faeces had 10 million times as much iron as Antarctic seawater.

This led Nicol to suggest that before commercial whaling began, baleen whales may have been the source of almost 12 percent of all the iron in the Southern Ocean’s surface water. Nicol says that when the Baleen whales started to be hunted and killed over the last century, the Southern Ocean lost a rich source of iron.

“Allowing the great whales to recover will allow the system to slowly reset itself,” he says. And this will ultimately increase the amount of CO2 that the Southern Ocean can sequester.

David Raubenheimer, a marine biologist who wasn’t involved in the current study, told New Scientist that the findings are important.
They highlight a specific ecological role for whales in the oceans “other than their charisma”, he says.
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Please see a related report about the food chain of whales.

http://buzz7.com/science/diatoms-key-to-evolution-of-whales.html

So if Diatoms are caused to bloom whale population would increase and then the iron would be recycled by the whales.

Diatoms key to evolution of whales

Sydney, Feb 19 (ANI): A new study by scientists has determined that a type of algae called diatoms have been key to the evolution of the diversity of whales.

According to a report by ABC Science, the research was carried out by Felix Marx of the University of Otago in New Zealand and Dr Mark Uhen of George Mason University in the US.

“The fossil record clearly shows that diatoms and whales rose and fell in diversity together,” said Marx, whose research was part of a PhD project under the supervision of Associate Professor Ewan Sordyce.

Marx and Uhen looked at the diversity of dolphins and whales (cetations) in the fossil record dating back 30 million years.

They then compared this with records of climate change and estimates of various food sources in the ocean.

Marx and Uhen measured the abundance of two different types of algae: nanoplankton and diatoms, which are key “primary producers” of the ocean – converting sunlight into food.

They found diatoms were the key to cetation diversity.

“The greater the diversity of diatoms found in the fossil record (a proxy for diatom abundance) the greater the diversity in species of whales and dolphins,” said Marx.

Marx said that the importance of diatoms is linked to their larger size, compared to nanoplankton.

The larger the primary producer, the fewer the links in the food chain between it and the top predator, and less energy is lost on the way.

“This suits a whale,” said Marx.

“You get a relatively large diatom, a krill can come along and eat the diatom and then a whale can come along and eat the krill. So you have two steps in the food chain,” he said.

The findings suggest it will be important for scientists to consider the role of diatoms when modelling the long-term effect of climate change on cetations. (ANI)

http://buzz7.com/science/diatoms-key-to-evolution-of-whales.html