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Phytoplankton are thought to be abundant under Antarctic sea ice – eye on the Arctic

Study shows there are enough “cracks and holes” around Antarctica to allow enough daylight to pass through the sea ice (NASA).
A team of researchers recently noticed evidence of potentially large blooms under the sea ice surrounding Antarctica. This discovery confirms the conclusions reached by an underwater scientific expedition ten years ago that had already reported the presence of a huge number of phytoplankton in the area.

The study reporting this discovery has been published in the scientific journal the border. It comes as scientists believe that, with a lack of light, the ice cap prevented the growth of phytoplankton for most of the year in the ocean around Antarctica.

However, the document shows that there are enough “cracks and holes” in the area to allow enough daylight to pass through the sea ice.

“In wide views from most satellites, the ice sheet can appear uniform and plate-like, reinforcing the idea that light would be too scarce and weak to support plant life below,” says Chris Horvat, a Brown University sea ice scientist. The lead author of the study.

But observed from and below the ocean surface — and by using NASA’s newest satellite — Antarctic sea ice is riddled with fractures and vents, the study says. “Sunlight streams through the cracks and provides energy for flowers under the ice in the Southern Ocean.”

Enough light under the ice

Experts point out that phytoplankton are to the ocean what grass is to land: these floating, plant-like organisms soak up the sun, absorb mineral nutrients and produce their own food (energy) through photosynthesis. “Phytoplankton are an essential source of food for other forms of life in the ocean and play a major role in recycling and disposing of carbon on the planet,” specifies the specialist, adding that they evolve almost wherever there are open, sunny areas in the ocean,” Horvat points out.

In addition to satellite imagery, Horvat and his colleagues collected several sources of data such as those collected by the buoys. These instruments can detect the presence of chlorophyll and carbonaceous particles. These could indicate the presence of phytoplankton.

“Reviewing data from more than 2,000 ice dives over seven years, the science team found that nearly all measurements showed an accumulation of phytoplankton even before the retreat of sea ice in the Southern Hemisphere spring and summer,” according to the study. .

Experts have also relied on ice sheet models to estimate the location and thickness of the Southern Ocean ice sheet, as well as how it is moving. They then found that 3 to 5 million square kilometers — an area larger than India — of the Southern Ocean covered in ice could let in enough light to support some blooms under the ice.

“Scientists have talked about the possibility of these blooms before, but this is the first time we’ve seen them under the ice in Antarctic waters,” Horvat said. “This discovery opens the way to a whole new way of looking at life around and under ice. Sea ice is much more interesting and diverse than you might think, and can support a wide variety of ecosystems.”

With information from Michael Karlwich of NASA