Friday, February 19, 2010

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)

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