Baltic Sea gasps for air

The World Wildlife Fund cautioned on Monday that the spread of so-called marine dead zones, where nothing can survive due to lack of oxygen, could cause the Baltic Sea ecosystem to collapse.

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"In the Baltic Sea, the marine dead zones could cause a total collapse of the entire ecosystem if their spread is permitted to continue," head of the WWF's Swedish branch Lasse Gustavsson said in a statement.

Ironically, marine areas are drained of life when they receive excess nutrients, mainly nitrogen and phosphorus from agriculture and other runoff, that act as fertilizers and enhance plant growth.

When the excess algae and other organisms die and sink to the bottom, they are decomposed by bacteria that suck up all the available oxygen, in a process called eutrophication.

Since 1995, the number of such dead zones around the world have soared from 44 to 169, according to WWF.

Around the world last year "marine dead zones covered an area double the size of arable land in Sweden, or 70,000 square kilometres (27,000 square miles)," the group said, citing data from the World Resources Institute.

Of the world's 10 largest marine dead zones, seven are according to WWF located in the Baltic Sea, which has long been considered to be on the verge of environmental catastrophe.

The semi-enclosed Baltic, which was in 2004 designated as a Particularly Sensitive Sea Area, takes far longer than many other large bodies of water to flush out toxic and other harmful substances.

"WWF demands quick and decisive action to reduce emissions, not least from agriculture around the Baltic Sea," the statement said.