Scientists: Warming triggers 'dead zone'

GRANTS PASS, Ore. - Bottom fish and crabs washing up dead on Oregon beaches are being killed by a recurring "dead zone" of low-oxygen water that appears to be triggered by global warming, scientists say.

The area is larger and more deadly than in past years, and there are signs it is spreading north to Washington's Olympic Peninsula.

Scientists studying a 70-mile-long zone of oxygen-depleted water along the Continental Shelf between Florence and Lincoln City have concluded it is being caused by explosive blooms of tiny plants known as phytoplankton, which die and sink to the bottom.

The phytoplankton are eaten by bacteria, which use up the oxygen in the water. The recurring phytoplankton blooms are triggered by north winds generating a rollover of the water column in a process known as upwelling.

"We are seeing wild swings from year to year in the timing and duration of the winds that are favorable for upwelling," Jane Lubchenco, professor of marine ecology at Oregon State and a member of the Pew Oceans Commission, said from Corvallis. "This increased variability in the winds is consistent with what we would expect under climate change."