Heavy rainfall in May washed the equivalent of an estimated 2,800 rail cars of nitrogen fertilizer down the Mississippi River and will create the third-largest fish-killing “dead zone” in the Gulf of Mexico in 32 years of monitoring, say federal scientists. They forecast a low-oxygen dead zone of 8,185 square miles, about the size of New Jersey.
If the forecast is correct, the dead zone would be 54 percent larger than the 5,309 square-mile average, said the National Oceanic and Atmospheric Administration. Nutrient pollution, primarily from human activities such as farming and wastewater treatment, stimulates an explosive growth in algae, which sinks into Gulf waters and depletes oxygen levels in the water as it decomposes. Researchers will monitor conditions this summer in the Gulf and produce a more precise estimate of the size of the dead zone in early August.
Fish and shellfish suffer when oxygen levels in the water are low. A study by Duke University says the dead zone may slow the growth of shrimp, which could mean higher costs in the future for large shrimp.