UNEP: Number of Marine 'Dead Zones' Increasing
The number of "dead zones" or low oxygenated areas in the world's seas and oceans may now be as high as 200, the United Nations Environment Programme (UNEP) announced on Oct. 19.
De-oxygenated zones are areas where algal blooms -- triggered by nutrients from sources such as fertilizer runoff, sewage, animal wastes -- and atmospheric deposition from the burning of fossil fuels, can remove oxygen from the water. The low levels of oxygen in the water make it difficult for fish, oysters and other marine creatures, as well as important habitats such as sea grass beds, to survive.
Experts claim that the number and size of deoxygenated areas is on the rise, with the total detected amount increasing every decade since the 1970s. They are warning that these areas are fast becoming major threats to fish stocks and thus to the people who depend upon fisheries for food and livelihoods.
While some dead zones are fleeting, others can persist for longer periods. In 2004, UNEP reported in its "Global Environment Outlook (GEO) Year Book" an estimated 149 sites known to have experienced or be suffering dead zones. Some of the earliest recorded dead zones were in places such as the Chesapeake Bay in the United States. Others have been reported in Scandinavian fjords.
The most well-known area of depleted oxygen is in the Gulf of Mexico. Its occurrence is directly linked to nutrients or fertilizers brought to the Gulf by the Mississippi River. Others have been appearing off South America, China, Japan, southeastern Australia and New Zealand.
Research by a team led by Professor Robert Diaz at the College of William and Mary, Virginia Institute of Marine Science in Gloucester Point, Va., whose work contributed to the GEO Year Book, now estimate that the number has climbed to 200 sites.
In advance of the Global Programme Action (GPA) for the Protection of the Marine Environment from Land-Based Sources (GPA) meeting in Beijing, Diaz told UNEP officials that the full list of new or newly-registered sites would be available in early 2007.
He said the sites include the Archipelago Sea, Finland; the Fosu Lagoon, Ghana; the Pearl River Estuary and the Changjiang River, China; the Mersey Estuary, United Kingdom; the Elefsis Bay, Aegean Sea, Greece; Paracas Bay, Peru; Mondego River, Portugal; Montevideo Bay, Uruguay; and the Western Indian Shelf.
Diaz appealed for more information and sightings from the Pacific Ocean where there are gaps in intelligence gathering.
The GPA's "State of the Marine Environment" report, released before the Beijing meeting, also identified nutrients as a key issue. Nitrogen exports to the marine environment from rivers are expected to rise globally by 14 percent by 2030 when compared with the amount documented in the mid 1990s, according to the report.
The "State of the Marine Environment" report can be found at http://www.gpa.unep.org/bin/php/igr/igr2/supporting.php.
Additional information on the GEO Year Book can be found at http://www.unep.org/geo/yearbook/yb2004/index.htm.
More information on the Beijing meeting can be found at http://www.gpa.unep.org/bin/php/igr/igr2/home.php.