Ocean Dead Zones are Spreading

By Jeremy Bloom on March 11, 2010 From Restoration campaign

A new type of dead zone is growing off our coasts - low-oxygen regions that kill fish.

“In some spots off Washington state and Oregon , the almost complete absence of oxygen has left piles of Dungeness crab carcasses littering the ocean floor, killed off 25-year-old sea stars, crippled colonies of sea anemones and produced mats of potentially noxious bacteria that thrive in such conditions,” McClatchy news reports.

Dead zones aren’t new - one type of dead zone appears every year at the mouth of major rivers like the Mississippi, where nutrients from farm fertilizers that have been washed into the rivers reach the ocean and serve as food for algae blooms. In the feeding frenzy, the algae use up all the oxygen in the water, and any fish in the area literally suffocate and drown. And the isolated waters of the deep ocean has always been low in oxygen, but sea life in the depths has adapted.

The other type of dead zone is more troubling. These have been happening in places like the Pacific Northwest coast off Oregon and Washington, and until now scientists weren’t sure why they were occurring - they just knew they were growing from year to year. It looks like the deep-see dead zones are spreading, rising toward the surface and even coming close enough to the coastline to affect the fishing there. On the Southern California coast, oxygen levels have dropped 20 percent over the past 25 years.

“The real surprise is how this has become the new norm,” said Jack Barth, an oceanography professor at Oregon State University . “We are seeing it year after year.”

We’ve reported at TENTHMIL about the problem of ocean acidification - as CO2 levels in the atmosphere rise, more is absorbed in the upper levels of the ocean, where it turns to carbonic acid. The rise in acidity is bad for fish all up and down the food chain, but is particularly bad for plankton and shellfish, because it interferes with their shell formation. Barth and other scientists say this is all related - climate change, acidification, and dead zones.

“It’s a large disturbance in the ecosystem that could have huge biological changes,” said Steve Bograd , an oceanographer at NOAA’s Southwest Fisheries Science Center in Southern California .
Bograd has been studying oxygen levels in the California Current, which runs along the West Coast from the Canadian border to Baja California and, some scientists think, eventually could be affected by climate change.

Want even more fun news? Some ocean life is happy with the change - jellyfish, in particular, love it. This may have something to do with the abundance of jellyfish that have been plaguing beaches in the US, Europe and Japan. There’s a world to look forward to - no fish, no shellfish… just beaches that are ankle-deep in jellyfish and slimy algae.


This was Ocean Dead Zones are Spreading, an entry in our Restoration Campaign from March 11, 2010. It was filed under Oceans and Dead Zones Birth.

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