Low-Oxygen-Level Zones in our Oceans Worrying Scientists

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Earth floating on ocean (hint)

Low-Oxygen-Level Zones in our Oceans Worrying Scientists which from an article on Yahoo News(2) suggest that the lower levels of oxygen in our planets oceans, and more directly, the Pacific Northwest of the United States could be another sign of deep-seated global changes linked to climate change. Scientists warn that the oceans complex ecosystem and fragile food chains could be altered.

Off the coasts of both Washington and Oregon, the nearly total lack of oxygen in some areas has left masses of Dungeness crab carcasses on the ocean floor, and has killed off 25 year old sea stars, crippled colonies of sea anemones (a solitary and often colorful sea animal with a squat cylindrical body topped by a ring of tentacles that attaches itself to rock or other nonliving material(3) and has produced thick masses of potentially toxic bacteria that flourish under low-oxygen level conditions.

This phenomena of low-oxygen levels is not new, at least in the deep oceans. What is new is that the areas of low-oxygen, or hypoxia are increasing and spreading, reaching towards the surface in some areas such as the Pacific Northwest and encroaching on the continental shelf in view of the coastline. This reduction in oxygen levels is striking according to oceanographer Greg Johnson, from the National Oceanic and Atmospheric Administration in Seattle. An oceanography professor from the Oregon State University, Jack Barth is surprised at how this has come to be the new norm and is a yearly occurrence now.

Oxygen levels off the coast of Southern California have decreased by approximately 20% over the last 25 years, and by as much as 1/3 in other areas over the past 50 years. As the ocean temperatures increase, the warmer surface water serves as a cap so to speak, and interferes with the natural exchange that typically allows the deeper oxygen depleted water to surface and replenish their oxygen supplies from the air. The current climate change models are consistent with the current lower-oxygen levels we are seeing, and previous studies have concluded that as the oceans absorb more co2 and other greenhouse gases, they become more acidic as well.

Francis Chan, a marine researcher at Oregon State states that “If the Earth continues to warm, the expectation is we will have lower and lower oxygen levels.” Scientists now say that some of these areas, including those off the Pacific Northwest, appear to be linked to broader changes in the oceans oxygen levels.

The Pacific Northwest waters face a peculiar dilema as a result of ocean circulation and hydro-thermodynamics. Scientists have known for some time now of the naturally low-oxygen zone located in the deeper waters off of the Pacific Northwest’s continental shelf. During the summer months, seasonal northerly winds which are aided by the Earth’s rotation push surface water away from the shoreline. This movement sucks the oxygen-poor water to the surface in a process called upwelling. Although that water that is drawn up from the oceans depths is low in oxygen, it has an abundant supply of nutrients, which fertilize the phytoplankton. These microscopic organisms form the lowest layer of one of the richest ocean food chains in the world. As the phytoplankton die, they sink and start to decay. This decaying of dead phytoplankton uses oxygen, which depletes the ocean oxygen levels even more.

In other times, southerly winds reverse the process in what’s known as down-welling. More recently, changes in the wind and ocean circulation since 2002 have disrupted what had been a delicate balance between the upwelling and down-welling cycles. Scientists now are discovering expanding low-oxygen zones near shore. In fact, the worst hypoxic zone off the Pacific Northwest coast was found in 2006. It covered nearly 1,200 square miles off Newport, Ore. , and according to Barth it was so close to shore you could hit it with a baseball. The zone covered 80 percent of the water column (A conceptual column of water from lake surface to bottom sediments(1). and lasted for an abnormally long four months.

“It is consistent with models of global warming, but the time frame is too short to know whether it is a trend or a weather phenomenon,” Johnson said.

Others appeared to be more definitive, quicker to relate the lower oxygen levels to global warming rather than to such weather phenomena as El Nino or the Pacific Decadal Oscillation, a shift in the weather that occurs every 20 to 30 years in the northern oceans. “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.

Because of the upwelling, the waters off of the coasts of Oregon and Washington are some of the most fertile ocean areas in the world. Similar upwelling occurs in only three other places, off the coast of Peru and Chile, in an area stretching from northern Africa to Portugal and along the Atlantic coast of South Africa and Namibia.

Scientists are not sure at this point how lowered oxygen levels will affect the oceans ecosystem. Bottom-dwelling species could be at the highest risk because they are slow and might not be able to escape from the lowered oxygen levels. Most fish typically can swim out of danger though. Some species like the Chinook salmon, may have to start swimming at shallower depths than they normally do though. Whether or not the low oxygen zones will change salmon migration routes remains to be seen. However, some species, like the jellyfish, will appreciate the lower-oxygenated waters. Jumbo squid, typically found off Mexico and Central America , can survive in lower oxygen level waters and can now be found in the waters off of Alaska .

Chan states that “It’s like an experiment, we are pulling some things out of the food web and we will have to see what happens. But if you pull enough things out, it could have a real impact.”

I don’t know about you, but I for one am concerned at this turn of events. Unfortunately, most people will claim this is a result of another natural phenomenon, and not global warming. The problem with that philosophy is rather large, and self destructive. Whether it is or isn’t climate change related remains to be proven 100%, and it will take years, more than likely decades to prove one way or another. The problem with that is if we just sweep it under the rug and forget about it, and 20 years down the road we did nothing to change our habits, and it does turn out to be climate change related, it will be too late to do anything about it.

We wasted 30 or more years denying the fact that global warming even existed, and that was time we could have been reducing co2 emissions and we could have avoided this whole situation altogether. Now we are facing the same obstacles, the only difference being that there is more acceptance of the problem. There are still many in denial for whatever reasons or agendas. The point is we shouldn’t be blowing all these phenomenon off as a patch of bad weather. The oceans may just be reacting to all the toxic waste we have dumped in there, both by air and land based toxins. Low-oxygen-level zones in our oceans worrying scientists and if the oceans ecosystems get changed or altered, it will have consequences, some of which could be quite severe, for us as a society and species. Time to act, and not react. We really need to get on the green train and hope we aren’t too late.


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