- Last summer every sea creature across an area twice the
size of Wales was asphyxiated by severely depleted oxygen levels in the
Gulf of Mexico. The same phenomenon, the marine equivalent of the ozone
hole, happened off South America, China, Japan, south-east Australia, New
Zealand, and up to 150 other places.
-
- A United Nations agency warned yesterday that the number
of these "dead zones", caused mainly by the run-off of nitrogen
fertilisers from intensive farming and sewerage from large cities, had
doubled in the past 15 years and was increasing all over the world.
-
- In a new report, the UN environment programme said that
150 sea areas were now regularly starved of oxygen and were becoming major
threats to already declining fish stocks, including those in Europe, where
areas of the Baltic Sea were lifeless for several months, as were parts
of the Irish Sea and the Adriatic.
-
- The Black Sea - the largest and oldest "dead zone"
in the world - supported only a few bacteria to a depth of 150 metres.
-
- "Humankind is engaged in a gigantic, global, experiment
as a result of the inefficient and often over-use of fertilisers, the discharge
of untreated sewage and the ever rising emissions from vehicles and factories,"
said Klaus Toepfer, the UN environment programme (UNEP) director. "The
nitrogen and phosphorous from these sources are being discharged into rivers
and the coastal environment or being deposited from the atmosphere, triggering
these alarming and sometimes irreversible effects."
-
- Some of the dead zones are less than one square kilometre,
whereas others are up to 70,000 sq km. Many have been found near the outlets
of big rivers such as the Mississippi and the Yangtze, which drain huge
industrial areas. Most lie off countries which heavily subsidise their
agriculture.
-
- "What is clear is that unless urgent action is taken
to tackle the sources of the problem, it is likely to escalate rapidly,"
he said.
-
- "Dead zones are especially dangerous to fisheries
because they afflict coastal areas where many fish spawn and spend most
of their lives before moving to deeper water", said UNEP officer Marion
Cheatle. "It is getting noticeably worse."
-
- She advised countries, which often share water basins,
to co-operate in reducing nitrogen discharges by cutting fertiliser use
or planting forests along rivers to soak up excess nitrogen. The "creeping
dead zones" have been noted since the 1970s but the speed of their
growth has surprised scientists who are only now beginning to understand
their mechanism.
-
- Robert Diaz, professor of marine science at Maryland
University and author of the marine section of the report, said dead zones
were fast becoming a bigger threat to fish stocks than over-fishing.
-
- He warned that global warming, with its likely increase
in rainfall, was likely to aggravate the problem, because it would increase
significantly the discharge of polluted water from rivers into oceans.
-
- The report, launched in South Korea at a meeting of 150
of the world's environment ministers, ranked dead zones as one of the top
20 threats to the global environment. Others included dust and sand storms,
more frequent around the world as land is degraded, and impending global
water shortages.
-
- More than one in three of the world's population is likely
to suffer chronic water shortages in the next few decades, according to
the report, while more than 2.4 billion people lack access to basic sanitation.
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- Guardian Unlimited © Guardian Newspapers Limited
2004 http://www.guardian.co.uk/waste/story/0,12188,1180697,00.html
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