Word: oxygenate
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Over the past two or three decades, scientists have noticed with growing alarm that vast stretches of coastal waters are turning into dead zones - patches of seabed so depleted of oxygen that few creatures, if any, can survive there. In 2004, the United Nations Environment Program (UNEP) took stock of the phenomenon - which is caused in large part by agricultural runoff - and pronounced it one of the biggest environmental problems of the 21st century. Two years later it noted that the number of identified dead zones, some of which cover thousands of square miles, had climbed from...
...them. Much of the world's fish supply is already troubled due to overfishing, dying reefs and the disappearance of marshland, mangrove forests and other coastal environments that serve as breeding grounds and nurseries for many valuable species. Biologists haven't been able to figure out how much oxygen depletion alone contributes to the decline of teetering fisheries - the question is hotly debated in marine-science circles these days - but few experts would disagree that an increase in dead zones can only be a detriment...
...Black Sea (which has since recovered) and a lobster fishery in the Kattegat, a patch of the North Sea between Denmark and Sweden. Other headline examples exist as well, but, more often, hypoxic waters have a relatively subtle impact on fish. "Most of the effects of low oxygen on fish stocks are what we call 'sub-lethal,' " says Diaz. "It doesn't kill the fish but stresses them. It affects their growth, it reduces their reproductive output, and makes them more susceptible to disease...
...nitrogen gets there in a couple of ways: through river water filled with fertilizer from farm runoff and from air polluted with tailpipe and smokestack emissions. When the algae die and sink to the ocean floor, bacteria there break them down, while consuming pretty much all of the available oxygen in the water. The bacteria also proliferate wildly, taking over the ecosystem and exacerbating the oxygen depletion. If conditions like strong currents, which are common in summer, prevent oxygen-rich water from the surface from mixing with lower layers, bottom-dwelling animals like lobsters, crabs and flounder in that area...
Take, for example, the case of a prolapsed umbilical cord. In roughly 1 out of every 300 births, the cord slips down into the birth canal before the baby does and risks cutting off the baby's oxygen supply. Kitty Ernst, an expert on midwifery at the Frontier School of Midwifery and Family Nursing in Hyden, Ky., says midwives are trained to push the baby's head back up off the cord and hold it there--the same way an obstetric nurse would--and get Mom to the hospital as an operating room is being prepared for her. "Your hand...