The ocean dead zone formed again last summer off Oregon, but was not as bad as years past.
Oregon State University scientists said Thursday that a break in the winds that are a factor in the severity of the phenomenon abated in July, allowing the low-oxygen waters to dissipate before they got too deadly to marine life.
While most dead zones around the world are formed by pollutants washing down rivers, the one off Oregon appears to be linked to global warming.
OSU oceanographer Jack Barth says there is increasing evidence that warmer ocean temperatures are making it more difficult for deep ocean waters to draw oxygen from the atmosphere, but they are still working to understand how climate change may affect the winds that are also a factor.
Copyright 2009 The Associated Press.