Dead zones spread along Oregon coast and Gulf of Mexico, study shows

Agricultural runoff from farms and livestock operations creates oxygen-depleted areas inhospitable to animal and plant life

Scientists recently surveyed the bottom of the Gulf of Mexico around Louisiana and Texas and what they discovered was a larger-than-average area of oxygen-depleted water - a dead zone" where nothing can live.

National Oceanographic and Atmospheric Administration (NOAA) scientists announced their findings this week: about 4m acres of habitat in the Gulf are unusable for fish and bottom-dwelling species. The researchers had estimated a smaller dead zone this year, predicting an average-sized area.