Saharan dust storms sustain life in Atlantic Ocean

July 21st, 2008 - 5:03 pm ICT by IANS  

London, July 21 (IANS) Saharan dust storms help sustain life over large regions of the North Atlantic Ocean, according to a latest study. Liverpool University researchers found that plants are able to grow in these regions because they are able to take advantage of iron minerals in Saharan dust storms.

This allows them to use organic or recycled material from dead or decaying plants when nutrients such as phosphorous - an essential component of DNA - in the ocean are low.

Scientists also mapped the distribution of nutrients including phosphorus and nitrogen and investigated how organisms such as phytoplankton are sustained in areas with low nutrient levels.

George Wolff of Liverpool University explained: “We found that cyanobacteria - a type of ancient phytoplankton - are significant to the understanding of how ocean deserts can support plant growth.”

“Cyanobacteria need nitrogen, phosphorus and iron in order to grow. They get nitrogen from the atmosphere, but phosphorus is a highly reactive chemical that is scarce in seawater and is not found in the earth’s atmosphere.

“Iron is present only in tiny amounts in seawater, even though it is one of the most abundant elements on earth.

“Our findings suggest that Saharan dust storms are largely responsible for the significant difference between the numbers of cyanobacteria in the North and South Atlantic.”

Wolff said the dust fertilises “the North Atlantic and allows phytoplankton to use organic phosphorous, but it doesn’t reach the southern regions and so without enough iron, phytoplankton are unable to use the organic material and don’t grow as successfully”.

Ric Williams, co-author of the research, added: “The Atlantic is often referred to as an ‘ocean desert’ because many nutrients, which are essential in plant life cycles, are either scarce or are only accessible in the darker depths of the ocean.

The research was published in Nature GeoScience.

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