Gulf of Mexico dead zone is largest ever

The 2017 dead zone in the Gulf of Mexico was the largest ever measured, scientists reported on Aug. 2. In late July, scientists from Louisiana State University and the Louisiana Universities Marine Consortium found the area of low or no oxygen in deep waters off the coast of Louisiana and northeast Texas reached 22,730 km². That’s the largest found since researchers started measuring it in 1985, the U.S. National Oceanic & Atmospheric Administration says. The previous record of 22,007 km² was set in 2002, NOAA adds. Each spring, the Mississippi River carries nitrogen and phosphorus from farm fields and urban areas within its massive watershed into the Gulf. There, algae consume the nutrients and reproduce rapidly. Eventually, the microorganisms die and drift to bottom waters, where decomposers polish them off, using up dissolved oxygen in the process. Low oxygen levels can decrease reproduction of some fish, reduce the average size of shrimp, and kill bottom-dwelling organisms that can’t move to other areas.