Iron fertilisation would 'significantly' change deep-sea ecosystems

June 24, 2011 by Tamera Jones, PlanetEarth Online, PlanetEarth Online
Iron fertilisation would 'significantly' change deep-sea ecosystems
The sea-bed is covered with a complex mix of creatures.

Adding iron to the oceans in an effort to curb growing emissions of carbon dioxide (CO2) in the atmosphere would lead to 'significant changes' in deep-sea ecosystems, the latest study suggests.

The study, led by UK researchers, found a big difference in the types and numbers of species living on the under a naturally iron-rich region of the Southern Ocean compared with a region free of iron.

The findings bring us a step closer to understanding the unintended consequences of this type of climate 'fix'.

'The type of fauna you get on the sea floor reflects what lives in the overlying ,' explains Professor George Wolff from the University of Liverpool, a member of the research team and lead author of the study.

'So if you manipulate the oceans over the long term, you'll influence the ecosystems you get at the .'

A global failure to cut has led some to suggest we need a 'Plan B' to save the world from dangerous climate change. That plan would involve controversial geo-engineering projects that aim to either remove CO2 from the atmosphere, or reflect the Sun's rays away from the planet.

Adding iron to the Earth's oceans is one such geo-engineering idea. The metal encourages , which use carbon dioxide and sunlight to grow. When these blooms die, they sink to the sea floor, taking their carbon with them, in effect locking it away for thousands of years.

Iron is hugely controversial and a study published in 2009 came to the conclusion that it might not be as effective as first hoped: researchers found that an iron-rich region of the ocean led to only three times as much carbon being locked away compared with an iron-poor area.

But exactly how such large-scale manipulations would affect deep-sea and ecosystems were, until now, largely unknown.

So, Wolff and colleagues from the universities of Liverpool, Aberdeen and the National Oceanography Centre set out to find out. 'We wanted to know how phytoplankton blooms at the surface of the ocean influence deep-sea fauna,' he says.

They compared deep-sea communities at two sites underneath two regions of the Southern Indian Ocean east and south of the Crozet Islands: one that is naturally fertilised by iron leached from the nearby islands, and another that's virtually iron-free. The sites are just 400 kilometres apart and both are 4200 metres deep.

Surprisingly, no one had looked at this before. 'The is a remote and wild place with heavy seas, so it's a difficult place to work and is very poorly studied,' explains Wolff.

They found the material that reaches the sea floor contains much more fresh organic matter like essential fatty acids and pigments called carotenoids in the iron-rich region than at the iron-free site. They say this probably comes from the earlier spring phytoplankton bloom.

On the sea floor in the iron-rich area east of Crozet, they found a community of creatures that thrive on this organic matter, including lots of a new species of sea cucumber.

At the iron-free site, the community was very different and there were fewer animals.

'Sea cucumbers feed almost exclusively on 'freshly deposited detritus' on the sea floor, so are a good group to use to investigate the productivity of surface waters,' write the authors in their report.

'We hypothesize that artificial iron fertilisation would change communities if carried out over a long period of time,' says Wolff. 'But it's really up to the policy-makers to make these decisions.'

Indeed, a study published by the Royal Society in 2009 came to the conclusion that, while some geo-engineering projects might be feasible, governments should focus their efforts on reducing CO2 emissions instead, because the effects of manipulating CO2 levels are far from well understood.

This story is republished courtesy of Planet Earth online, a free, companion website to the award-winning magazine Planet Earth published and funded by the Natural Environment Research Council (NERC).

Explore further: Ocean iron and CO2 interaction studied

More information: Wolff GA, Billett DSM, Bett BJ, Holtvoeth J, FitzGeorge-Balfour T, et al. (2011) The Effects of Natural Iron Fertilisation on Deep-Sea Ecology: The Crozet Plateau, Southern Indian Ocean. PLoS ONE 6(6): e20697. doi:10.1371/journal.pone.0020697

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not rated yet Jun 24, 2011
Plan B appears good on the face of it, but we still have to study its entire impact on marine ecology. We don't want a situation that warrants emergency solutions like we are already facing in terrestrial domains; especially when our planet is 70% covered by the marine domain....
not rated yet Jun 24, 2011
Sounds like a good idea to me, though I'm interested to know what happened to the top and middle level ecosystems from the phytoplankton bloom. I can imagine how that bloom would be bad if this is done on a much larger scale. Potentially blocking out sunlight and O2 from being dispersed into lower levels.
1 / 5 (1) Jun 24, 2011
a study by the royal society, because they are free to look into matters that may potentially destroy this planet and see if they can fiddle with it. Sounds like her majesty is going to send us down the path of never turning back from geo-engineering. We can turn back now, but it looks like since it's already happening. How do we know this is resulting in good consequences for other places in the world? Maybe sunny olympic days in china resulted in something bad happening elsewhere? What if this is a weapon, couldn't it be used back and fourth in a cold war scenario with an unwitting population living it never knowing any better of it's existence. We know it is out there and it is only the rich people who want to do this so they have a free pass not to clean up their act.
not rated yet Jun 24, 2011
I still think the leaflet idea is the best because it would be easy to clean up with solar sails, just drop a bunch of reflective leaflets into the area in between the sun and earth to reflect some of the light away from us, then once we have transitioned to a no-carbon lifestyle we use the solar sails to sweep up the leaflets
3.5 / 5 (2) Jun 24, 2011
Geo-engineering scares me. It's a classic devil you know vs. the devil you don't. I guarantee not every particle of iron would be consumed, how would an iron dusting effect things like reefs or kelp or what if it washes on shore, how is the tidal ecosystem affected... Too many unknowns IMHO.

Just look at the Matrix. Take away their sun and BAM!, you're a battery.
not rated yet Jun 24, 2011
Because clearly robots are about to enslave us :P
not rated yet Jun 24, 2011
This was always something I wanted to see happen. You fertilize algae blooms, you fertilize everything that feeds off them, which is everything. Algae makes up 71 percent of the oxygen production in the world? Not only is it a means of controlling our out of control carbon emissions, but as the dominant species on the earth by far maybe this is natures way of telling us we need to start giving back to compensate for eeeeeeeeeverything that we're taking.

Even without carbon emissions we've long stripped the ocean of much of its life, namely fish. Not only could this potentially reinvigorate life in the sea, which has been on the decline since the invention of the boat, but it could also help to feed our clearly unstoppable population growth. And I'm well aware that the starving people in africa and south east asia is because of politics and corruption and not because of scarcity, but in 50 years that wont be the case.
Its not playing god, its our responsibility.

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