Phytoplankton provide half planet's oxygen

Can soak up 45 billion tons of carbon dioxide per year Tiny ocean 'phytoplankton' have a huge impact on Earth's climate - and understanding them could be key to the planet's future health. Canadian scientist Maria Maldonado is researching why the phytoplankton thrive in some areas, and how they survive in areas with hostile conditions.
The tiny single-celled algae soak up 45 billion tons of carbon dioxide every year - transferring 16 billion tons to the deep ocean. They provide half the planet's oxygen supply.
Understanding them is vital to understanding - and regulating - our planet's health, Maldonado says.
Maldonado is presenting her research at the 178th annual meeting of the American Association for the Advancement of Science, in Vancouver.
The deep ocean is one of the Earth's natural carbon 'sinks' and will hold carbon from the atmosphere for centuries.
The biological carbon pump controls the carbon dioxide content in the upper ocean, which in turn regulates atmospheric carbon dioxide levels—and, as a result, controls climate change.
Scientists have established that low iron concentrations in ocean water limit phytoplankton growth, since phytoplankton use iron to  grow.
In these iron-limited environments (which make up approximately 30 per cent of the global ocean), the biological pump becomes inefficient and the ocean's ability to absorb carbon dioxide is reduced.
For the past 20 years, Maldonado has been examining how phytoplankton adapt to and survive in, these iron-limited environments.
'In essence, what we are illustrating is that they have evolved to deal with iron limitation, and we are trying to figure out how they have adapted to take up iron more efficiently,' she says.