Prior blogs have described both the size, nature, and cause of the Gulf of Mexico dead zone, a subsea region where the water contains too little oxygen to support life.
In June of 2011, researchers predicted that the annual dead zone might be the biggest ever (9,500 sq.mls.). Owing to the fortuitous arrival of stormy weather, this year's dead zone peaked at approximately 6,800 sq.mls. That's the good news.
The bad news? Substantial portions of the affected Gulf were not merely low in oxygen, they were virtually devoid of it from the surface to the seafloor. One effect of this depletion is that when oxygen loss occurs at the seafloor, the sediment yields hydrogen sulfide. The situation was so bad that bottom dwellers like eels and brown shrimp were found swimming near or on the surface. Not only were these animals suffering from the presence of little or no oxygen, but they were also escaping from the hydrogen sulfide, the exposure to which can be fatal. [Prior posts have also noted that low oxygen oceanic environments can have estrogenic effects, turning some male fish into females.]
Reports related to this subject matter can be found at: http://www.therepublic.com/view/story/4f76bbf331b34542b315ebd9b8fdf3aa/LA--Dead-Zone/, http://www.chron.com/disp/story.mpl/ap/tx/7679015.html, and http://www.msnbc.msn.com/id/43987473/ns/technology_and_science-science/.