It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
These "dead zones" occur where there are disturbances to the nutrient-rich ocean currents, which are driven by coastal winds.
Extreme marine suffocations have occurred off the west coast of the US every year for the last five years.
The most intense event, which left the ocean floor littered with the carcasses of crabs, happened in 2006.
Other coastal countries including Chile, Namibia and South Africa have also been affected.
An even more catastrophic event occurred in 2006 when the amount of upwelling doubled, leading to a huge influx of nutrients and a supercharged plankton bloom.
When these sank to the ocean floor they stripped the water column of oxygen, creating a 3,000 sq km (1,150 sq miles) dead zone, where creatures unable to swim away suffocated en masse.