Science Interviews

Interview

Sat, 11th Dec 2010

Does it snow in the sea?

Kate Hendry, Woods Hole Oceanographic Institute

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Diatoms are the gems of the ocean that lock up carbon and are vital for all sorts of other creatures from krill to penguins.

DiatomsFind out more:

Diatoms at the Tree of Life.

Kate – Diatoms are a kind of microscopic algae. So they’re a bit like plants, they can photosynthesize which means they can use the energy in sunlight to fix carbon, carbon dioxide from the atmosphere into their food, into their carbohydrates and sugars.

And they grow in the surface of the ocean but they can grow pretty much anywhere. They live in rivers in lakes and puddles, pretty much anywhere you look.

They make their shells out of silica or sort of glass like substance and there shells are really very beautiful, very intricate designs. They can be pillbox shapes, needles or even stars.

So although they’re really small, diatoms when they grow together form big clumps. They produce this sticky substance that makes them stick together in big mats. And this means that when they die they can sink really quickly and these big clump mats can fall out of the surface ocean to the sediments. And because they do this they’re sometimes known as marine snow.

An because of this, because they sink very quickly, they’re really important for taking carbon dioxide out of the atmosphere, so when they photosynthesize and lock up all this carbon into their shells, when they sink they can transport this carbon from the surface to the sediments and there it can be locked away.

We’ve already noticed however changes in the different types of algae growing in different regions in response to climate change.

So for example in the West Antarctic Peninsular, we’re actually seeing in recent decades a change from populations dominated by large diatoms to those dominated by a different type of plankton called salps.

And not only has this changed how carbon is taken up in this area but it’s also had knock on effects for the ecology. So not only is this impacting organisms like fish and krill that live off diatoms but also organisms higher up the food chain like penguins and seals.

So, I think that although that they’re tiny organisms, diatoms are some of the most beautiful creatures in the sea and they’re also really important both for local ecology and for global climate.

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