For the fifth straight year, a dead zone, now the size of Rhode Island, has appeared off the coast of Oregon. As Julia Whitty reported in Mother Jones’ special report on the fate of the ocean,
“Dead zones occur wherever oceanic oxygen is depleted below the level necessary to sustain marine life, a result of eutrophication, or the release of excess nutrients into the sea, usually from agricultural fertilizers….For sea life, it’s as if all the air were suddenly sucked out of the world. Those creatures that can swim or walk away fast enough may survive. Those that can’t, die.”
And dead zones are further exacerbated by global warming. As the New York Times reports on the Oregon dead zone:
Jane Lubchenco, a marine biologist at Oregon State University, said the phenomenon did not appear to be linked to recurring El Niño or La Niña currents or to long-term cycles of ocean movements. That made Dr. Lubchenco wonder if climate change might be a factor, she said, adding, “There is no other cause, as far as we can determine.”
More on the state of dead zones, after the jump:
From Julia Whitty’s Mother Jones feature:
Robert Diaz, a hypoxia expert from the Virginia Institute of Marine Science, calculates the global number is doubling every decade. Furthermore, he suggests that at least in some areas hypoxia is rapidly becoming a greater threat to fish stocks than overfishing, since it disperses them off their feeding, spawning, and maturation grounds. And he predicts that hypoxic zones will only increase as the ocean warms further, citing a modeling study predicting that a doubling of atmospheric carbon dioxide will double rainfall across the Mississippi River Basin, increasing runoff by 20 percent and decreasing dissolved oxygen in the northern Gulf by up to 60 percent.
Close to 50 hypoxic zones fester on the coasts of the continental United States, affecting half of all our estuaries. The situation is worse in Europe, with 14 persistent dead zones that never go away, and almost 40 others occurring annually, the biggest and worst being the 27,000-square-mile persistent dead zone in the Baltic Sea, which is nearly the size of South Carolina. Not all of these are caused by riverborne nitrogen. Fossil fuel-burning plants along the Ohio River loft airborne emissions that help create hypoxic conditions in the Chesapeake Bay and Long Island Sound. Excess phosphorus from human sewage, as well as nitrogen emissions from automobile exhaust, impact Tampa Bay. Other dead zones suffer from the nitrogen fixation produced by leguminous crops.
Interestingly, we know how to solve these problems. Rabalais and others have engineered an action plan that calls for the reduction of the Gulf hypoxic zone to just under 2,000 square miles by 2015. “There are modeling studies that show if you reduce nitrogen fertil-izer applications by 12 to 14 percent, you can reach the target without losing crop production. And there are lots of ways to reduce,” she says, listing best management practices such as a reduction in fossil fuel use, cleaner municipal wastewater discharge, restoring wetlands, regulating pen-feed operations, and banning wintertime fertilizer applications.
