Washington, DC - Pollution, coupled with stresses from climate change, is making U.S. coastal waters sicker by the year, new research by leading U.S. environmental and scientific agencies concludes.

So-called "dead zones," caused primarily by runoff from agricultural fertilizers, sewage and landscaping, are occurring 30 times more frequently than they did 50 years ago, the report, issued by the White House, concludes. Dead zones have a condition called hypoxia — areas so low on oxygen that fish and other sea animals either die or become unable to reproduce.

The largest such area in the world is the Baltic Sea in northern Europe, followed by the areas off the coasts of Louisiana and Texas in the Gulf of Mexico, and Washington and Oregon in the Pacific Northwest.

Nearly half of the 647 waterways assessed for the report were found to suffer from hypoxia.

It was the final of five reports requested by Congress under the Harmful Algal Bloom and Hypoxia Amendments Act of 2004. That law was one of several federal laws passed in recent years to address ocean dead zones. The new report is more evidence that efforts to protect the ocean must be stepped up even more, scientists say.

United States coastal waters are "vital to our quality of life, our culture, and the economy," wrote John Holdren, President Obama's top science adviser, and Nancy Sutley, chair of the White House Council on Environmental Quality. "Therefore, it is imperative that we move forward to better understand and prevent hypoxic events, which threaten all our coasts."

When large amounts of nutrients such as nitrogen and phosphor seep into creeks and rivers and then into the ocean, abnormal algae blooms occur, usually during the summer. The algae are decomposed by bacteria that also deplete oxygen in the water.

Oysters, mussels and other sea animals that can't relocate when oxygen gets scarce may die when this happens, disrupting the local food chain. But fish that could normally escape dead zones can also perish when oxygen levels suddenly drop too low, says the report, issued by the White House Office of Science and Technology Policy. Local fisheries and communities along the coast, in turn, suffer when fish and shellfish die.

Policies have been in place for a long time to try to address hypoxia — for example, through better erosion controls and wetland management, and through incentives to farmers who cease production in certain sensitive areas. But the programs have not managed to stem the flow of nutrients to large watersheds such as the Gulf of Mexico.

Titled Scientific Assessment of Hypoxia in U.S. Coastal Waters, the report emphasizes that "major new initiatives" should be launched to determine which existing watershed protection methods are effective and which are not. Continued research is also needed to find new and better ways to protect coastal areas, it says.

CLIMATE CHANGE MAY WORSEN DEAD ZONES

Warmer ocean temperatures appear to be adding to the hypoxia problem, the report said, confirming other recent scientific research. Warmer surface water can lead to a loss of plankton and other biomass needed to feed fish and other sea animals. This is reducing biodiversity in an already stressed ecosystem. The dead zone off the Pacific Coast, where there is little agricultural production, suggests that factors other than runoff may be at play.

"The report shows good progress on research into the causes of hypoxia and the specific management [required] to restore systems … but we still have a long way to go to reduce this environmental threat," said Jane Lubchenco, administrator of the National Oceanic and Atmospheric Administration, the agency that led the preparation of the report to Congress.

"The discovery of a new seasonal hypoxic zone off the coast of Oregon and Washington that may be linked to a changing climate emphasizes the complexity of this issue," Lubchenco said.

SOURCE: National Oceanic and Atmospheric Administration (NOAA)