NEW ORLEANS -- The dead zone off the coasts of Louisiana and Texas should be considerably smaller than usual this year -- about the size of Rhode Island, rather than larger than Jamaica, researchers say. That's because the Mississippi and Atchafalaya rivers are carrying much less nitrogen and other nutrients than usual into the Gulf of Mexico, according to scientists from the National Oceanic and Atmospheric Administration.
Nancy Rabalais, head of the Louisiana Universities Marine Consortium in Cocodrie, and other researchers will head out Saturday on a week-long research trip to measure the dead zone's summer peak. NOAA is predicting that about 1,500 square miles of Gulf of Mexico waterbottom are likely to be without oxygen this year. That's less than one-third the 4,900-square-mile average (Jamaica is 4,250 square miles) and less than one-fifth the record.
The NOAA forecast is based on the nutrients which feed algae, which eventually die and fall to the ocean floor. When still weather allows the lighter fresh water pouring in from the rivers to remain above the saltier water of the Gulf, the algae's decay uses up oxygen faster than it can be replenished from the surface. Eventually, the lower layer holds too little oxygen for fish and other aquatic life.
The low "nutrient loads" probably were caused by lower-than-normal snow and rainfall across much of the Mississippi River Basin, according to NOAA. In addition, tropical storms and hurricanes have kept the Gulf of Mexico stirred up lately, noted Nancy Rabalais, head of the Louisiana Universities Marine Consortium."
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