'Dead Zone' causing wave of death off Oregon coastAugust 11, 2006Corvallis, Ore. - The most severe low-oxygen ocean conditions ever observed on the West Coast of the United States have turned parts of the seafloor off Oregon into a carpet of dead Dungeness crabs and rotting sea worms, a new survey shows. Virtually all of the fish appear to have fled the area. Scientists, who this week had been looking for signs of the end of this "dead zone," have instead found even more extreme drops in oxygen along the seafloor. This is by far the worst such event since the phenomenon was first identified in 2002, according to researchers at Oregon State University. Levels of dissolved oxygen are approaching zero in some locations. "We saw a crab graveyard and no fish the entire day," said Jane Lubchenco, the Valley Professor of Marine Biology at OSU. "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.
"Seeing so much carnage on the video screens was shocking and depressing," she said. OSU scientists with the university-based Partnership for Interdisciplinary Studies of Coastal Oceans, in collaboration with the Oregon Department of Fish and Wildlife, used a remotely operated underwater vehicle this week to document the magnitude of the biological impacts and continue oxygen sampling. This recent low-oxygen event began about a month ago, and its effects are now obvious. Any level of dissolved oxygen below 1.4 milliliters per liter is considered hypoxic for most marine life. In the latest findings from one area off Cape Perpetua on the central Oregon coast, surveys showed 0.5 milliliters per liter in 45 feet of water; 0.08 in 90 feet; and 0.14 at 150 feet depth. These are levels 10-30 times lower than normal. In one extreme measurement, the oxygen level was 0.05, or close to zero. Oxygen levels that low have never before been measured off the U.S. West Coast. "Some of the worst conditions are now approaching what we call anoxia, or the absence of oxygen," said Francis Chan, a marine ecologist with OSU and PISCO. "This can lead to a whole different set of chemical reactions, things like the production of hydrogen sulfide, a toxic gas. It's hard to tell just how much mortality, year after year, these systems are going to be able to take." One of the areas sampled is a rocky reef not far from Yachats, Ore. Ordinarily it's prime rockfish habitat, swarming with black rockfish, ling cod, kelp greenling, and canary rockfish, and the seafloor crawls with large populations of Dungeness crab, sea stars, sea anemones and other marine life. This week, it is covered in dead and rotting crabs, the fish are gone, and worms that ordinarily burrow into the soft sediments have died and are floating on the bottom. The water just off the bottom is filled with a massive amount of what researchers call "marine snow" - fragments of dead pieces of marine life, mostly jellyfish and other invertebrates. As this dead material decays, it is colonized by bacteria that further suck any remaining oxygen out of the water. "We can't be sure what happened to all the fish, but it's clear they are gone," Lubchenco said. "We are receiving anecdotal reports of rockfish in very shallow waters where they ordinarily are not found. It's likely those areas have higher oxygen levels.\\\ Oregon State University | |||||||||||||||||||||
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Related Dead Zone News Articles Study shows continued spread of 'dead zones' A global study led by Professor Robert Diaz of the Virginia Institute of Marine Science, College of William and Mary, shows that the number of "dead zones"-areas of seafloor with too little oxygen for most marine life-has increased by a third between 1995 and 2007. NOAA and Louisiana scientists predict largest Gulf of Mexico 'dead zone' on record NOAA-supported scientists from the Louisiana Universities Marine Consortium and Louisiana State University are forecasting that the "dead zone" off the coast of Louisiana and Texas in the Gulf of Mexico this summer could be the largest on record. LSU and Ohio State Battle on Football Field, Collaborate in Research Field LSU and Ohio State University will battle for the BCS National College Football Championship in the Superdome early next week, but if the game was held in the Louisiana wetlands instead, the entire field would disappear before halftime. Stronger EPA leadership needed to improve water quality in Mississippi River The U.S. Environmental Protection Agency must take a more aggressive leadership role in implementing the Clean Water Act if water quality in the Mississippi River and the northern Gulf of Mexico is to improve, says a new report from the National Research Council. Low oxygen in coastal waters impairs fish reproduction Low oxygen levels in coastal waters interfere with fish reproduction by disrupting the fishes' hormones, a marine scientist from The University of Texas at Austin Marine Science Institute has found. UD scientists take underwater robot on Black Sea expedition Using a novel underwater robot, University of Delaware marine scientists will help reveal the mysteries of the Black Sea's geology and maritime history, including ages-old shipwrecks, during an international expedition that is now underway. Deadly hypoxic event finally concludes The longest, largest and most devastating hypoxic event ever observed in marine waters off the Oregon Coast has finally ended. Insect predation sheds light on food web recovery after the dinosaur extinction The recovery of biodiversity after the end-Cretaceous mass extinction was much more chaotic than previously thought, according to paleontologists. Marine 'dead zone' off Oregon is spreading A hypoxic "dead zone" has formed off the Oregon Coast for the fifth time in five years, according to researchers at Oregon State University. Researchers identify energy gains and environmental impacts of corn ethanol and soybean biodiesel The first comprehensive analysis of the full life cycles of soybean biodiesel and corn grain ethanol shows that biodiesel has much less of an impact on the environment and a much higher net energy benefit than corn ethanol, but that neither can do much to meet U.S. energy demand. More Dead Zone News Articles |
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