OAK RIDGE, Tenn., April 22 (UPI) -- U.S. scientists say improved management of crops and perennials could help alleviate the problem of hypoxia in the Gulf of Mexico each spring.
Each year, hypoxia -- a lack of adequate oxygen -- kills thousands of fish and shrimp in an area about 6,000 square miles, usually off the coast of Louisiana, west of the Mississippi River Delta.
Now scientists led by Virginia Dale of the Oak Ridge National Laboratory have determined the problem is caused, in part, by fertilizer run-off from the Mississippi basin, which drains about 48 percent of the United States.
The scientists say the nutrients combined with stratification caused by warm freshwater from the Mississippi and Atchafalaya rivers running into the Gulf's colder saltwater start the process. Algae grows, dies and sinks to the bottom, where it decomposes, using up oxygen in the process.
"Choices about what crops are grown and how they are planted, fertilized and harvested influence the effects of biofuels on native plant diversity, competition with food crops and effects on water and air quality," Dale said.
The team is recommending a 45 percent reduction in phosphorus and nitrogen use during April, May and June for five years.
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