Oceanic Dead Zones Off West Coast are the 'New Normal'

tags: , , , , , , ,

Millions of dead crabs are washing up onto Oregon and Washington state beaches from the offshore "dead zone".


Ever since it was first noticed by crab fishermen who hauled up hundreds of dead and dying crabs in 2002, the "dead zone" that popped up in the waters along the northwestern coastal shelf just off the coast of Oregon has claimed unknown millions of lives. This oxygen-depleted region has transformed formerly rich seafloor communities teeming with life into vast graveyards filled with the bodies of crabs, echinoderms, molluscs, sea worms and other creatures. This carnage was easily visible to a team of research scientists from Oregon State University, who sent an underwater vehicle, equipped with video cameras, into the depths to look around.

"We saw a crab graveyard and no fish the entire day," noted Jane Lubchenco, co-author of the papers that report on their discovery. Lubchenco is the Valley Professor of Marine Biology at Oregon State University.

"Thousands and thousands of dead crab and molts were littering the ocean floor, many sea stars were dead, and the fish have either left the area or have died and been washed away."

The team measured the dissolved oxygen in these dead areas and made a shocking discovery: there was almost none at all. When dissolved oxygen is 1.4 milliliters per liter, it is considered hypoxic for most marine life -- so a "dead zone" forms. However, some of the data collected by the team from one area off Cape Perpetua on the central Oregon coast showed that dissolved oxygen was as low as 0.5 milliliters per liter in just 45 feet of water; 0.08 in 90 feet; and 0.14 at 150 feet depth. Data collected from other areas off the Oregon coast are similar (figure 1);

Figure 1: Dissolved oxygen profiles during the upwelling season (mid-April to mid-October) in the upper 800 m of the continental shelf and slope of Oregon (42.00°N to 46.00°N). (A) 1950 to 1999 from the World Ocean Database and Oregon State University archives (n = 3101 hydrocasts, blue). (B) (A) with additional data for 2000 to 2005 (n = 834 hydrocasts, green). (C) (A) and (B) plus data for 2006 (n = 220 hydrocasts, red). The black vertical line denotes the 0.5 ml l-1 threshold. (Insets) Overlapping locations of hydrographic (blue, green, and red) and remotely operated vehicle (black) stations through time and the 100-m and 1000-m isobaths. [larger view of data graphs].

Oxygen concentrations that low have never before been measured off the U.S. West Coast (figure 1A).

These low-oxygen "dead zones" have suddenly been appearing along various coastal regions throughout the world recently and result from a variety of causes. For example, a low-oxygen zone appears each spring off the coast of Louisiana due to fertilizers in farm runoff and sewage present in the Mississippi River. When the Mississippi flows into the sea, it creates a nutrient-rich area that triggers huge but short-lived algal blooms that soon die, sink to the seafloor and are decomposed by bacteria that produce toxic sulfide gases. As the bacteria break down the dead algae and other microscopic plants and animals, dissolved oxygen is removed from the seawater, thereby creating a low-oxygen "dead zone" where most creatures cannot survive.

According to scientists, the dead zone off the West Coast of North America has another cause: global warming. Here's how it works: Winds cause the oceanic rivers of nutrients, such as the California Current in this case, to flow upwards from the deep, carrying nutrients and phyoplankton into the sunlight, which triggers the phytoplankton to reproduce, to "bloom". This is the normal state of things, but since global warming has been causing land temperatures to increase, these winds have become stronger and more persistent. This is not normal because it prolongs the oceanic upwelling, producing a surplus of phytoplankton that isn't consumed and subsequently dies, and sinks to the seafloor to decay. As the bacterial-mediated breakdown occurs, dissolved oxygen in the surrounding water is depleted to dangerously low levels -- sometimes there is none at all. This causes every living thing in the area to either die or flee, further adding to the ecological imbalance.

Unfortunately, this cycle has repeated itself every summer and autumn ever since those Oregon crab fishermen first noticed its effects in 2002. Neither El Nino nor La Nina have any demonstrable effect on this phenomenon. This particular dead zone represents one of the many ways in which climate change is damaging the global environment: by depleting the concentrations of dissolved oxygen in a benthic marine habitat, much larger marine communities that cannot adapt quickly enough are also severely disrupted.

"We seem to have crossed a tipping point," Lubchenco observed. "Low-oxygen zones off the Northwest coast appear to be the new normal."

This paper was published in Science.


Chan, F., Barth, J.A., Lubchenco, J., Kirincich, A., Weeks, H., Peterson, W.T., Menge, B.A. (2008). Emergence of Anoxia in the California Current Large Marine Ecosystem. Science, 319(5865), 920. | DOI: 10.1126/science.1149016 [PDF]. (story and data figure).

LATimes (quotes and "dead zone" graphic).

More like this

I met Lubchenco many years ago when she was a young and eager beaver and it has been interesting watching her career grow. She doesn't know me, but I do read her interesting work.

Living as I have, in Oregon and Washington for the last couple decades, this news has me just a little pissed off.

One has to wonder if there aren't also terrestrial zones of hypoxia/anoxia though: How else to account for Bush, Cheney, and the rest of the legions of "climate skeptic" morons' mental damage?

Deniers like to pooh-pooh mathematical models and computer simulations. It's a little different when the damage is right there in front of them.

By Nebularry (not verified) on 16 Feb 2008 #permalink

It's foolish to blame Bush/Cheney for this, it is the American public whose ravenous consumption of resources has led to this. We do not to leave air conditioners running in office buildings all night long, electric lights brightening up cities when no one is out, and building house and car after house and car that is not energy efficient.

By Dr. William Bennett (not verified) on 16 Feb 2008 #permalink

I keep wondering if it would help re-oxygenate these zones if we all go buy a bunch of OxyClean (brand), or similar products and go dump them into these damaged areas of the coastal waters? Or hydrogen peroxide?

In reading articles about the dead zones, there are often lists of things to NOT do......but what can we DO?

Any thought given to the fact that the west coast is part of the ring of fire, a geologically active region of the world? Volcanos can emit toxic gases that are more dense and therefore displace oxygen. Mountaineers succumb to these "oxygen deprived zones" each year. While GW might indeed be a factor, there could certainly be other possibilites....

By whatabout (not verified) on 16 Feb 2008 #permalink

Oh no, please do not dump abrasive cleaning products into the water! Dead zones are mainly a result of stormwater and groundwater drainage--especially from fertilizers that cause algal blooms that suffocate all marine life below (usually within less than 100 meters from the shore, as this is where most of the bottom of the ocean food chain live).

I think what you can do to help is to:
* buy organic/sustainable produce and other products
* start using "green friendly" dishsoaps and detergents
* stop using fertilizers (for gardens, lawns, etc)
* read up more on this stuff to find out what you can do to help!


Likely fishes detect these areas are able to escape.

Are there indications the deadzones are related to micro or macro changes in oceanic current? I find it hard to believe it is just surface temperature and nitrates related. Not that those are good things.

I wonder if the drought conditions are causing different farming techinques in some ways.

Deb Shaw:
One thing you can do is seek out organic and biodynamically produced fruit, vegies, dairy, eggs & meats. Unless you vote with your dollars for environmentally responsible and sustainable farming practices, you are simply being a part of the problem. While you keep buying produce from "chemical farms", those farms have very little incentive to change their ways. Government regulations to stop polluters are too slow and ineffective: stop giving your money to the destroyers, and encourage the nurturers.

By CookedGoose (not verified) on 16 Feb 2008 #permalink

There's a huge issue most people are ignoring.

Synthetic fossil fuel based fertilizers have for the most part displaced human and animal waste which is now mostly flushed into the ocean instead of being returned to the soil. Such behavior not only strips the soil of the trace elements needed for life, it also dumps them into the ocean where they feed the megablooms that are killing everything else.

I invite everyone to click the URL that goes to a little BBC article because it's not just the US - it's global. Then, you can google peak fish because we're already past it.

A recent study found that the total north Atlantic fishing fleet now brings in less than the top 10 wooden sailing ships did before WW1. Think about it.

Damn... that was a really interesting article right up until bloody global warming was whipped out. Tedious boogeyman, do some real science please!

these zones are not 'dead'; they are anaerobic. there are plenty of microbes capable of living without oxygen.

By VembaTsith (not verified) on 17 Feb 2008 #permalink

you say global warming is the cause but what about the tons and tons and still more tons of deadly nerve agents and other
deadly substances dumped there by the DOD. America has lined the shores with all manner of toxic soup.this is enough to cause an extermination of humans. do not swim off the shores of America.

Vemba, the survival of unicellular creatures does not negate the tremendous impact of the wide spread deaths of the multicellular creatures.

By Samantha Vimes (not verified) on 18 Feb 2008 #permalink

In response to #5 there is somthing you can do and it's called AquaPuck which will accomplish exactly what you proposed. It is our patented technology which delivers a time release oxygen and benefical bacterial to correct the effect of the dead zone. Take a look at our web site and if you require further information give us a call.