NEW ORLEANS (AP) — A Louisiana researcher says the "dead zone" that develops every spring and summer in the Gulf of Mexico is smaller than usual this year. Nancy Rabalais (RAB uh LAY) of the Louisiana Universities Marine Consortium says the area of low-oxygen in gulf waters covers 2,889 square miles. In a news release, Rabalais says that is the fourth smallest dead zone measured since mapping of the zones began in 1985. The dead zone forms because fertilizer and other nutrients run into the Mississippi River, which empties into the gulf. The nutrients feed huge numbers of microscopic organisms. When they die, their decomposition uses up oxygen. The consortium says the dead zone is small this year because record drought across the country meant fewer nutrients were washed into the river.