According to a study financed by the NOAA Center for Sponsored Coastal Ocean Research, it would appear that the dead zone which usually develops in the Gulf of Mexico in the summer is smaller now than it's been over the past few years.
Dead zones are also called hypoxic, and occur when the amount of oxygen available in the water decreases drastically. Nutrient runoff from the mainland or the excessive development of algae can both cause this phenomenon to intensify.
“In all, we found about 1,580 square miles of hypoxia compared to about 3,400 square miles in August 2011. What has happened is that the drought has caused very little fresh-water runoff and nutrient load into the Gulf, and that means a smaller region for marine life to be impacted,” Texas A&M experts say.
Once rain returns to the United States, nutrient runoff is expected to trigger the development of a large dead zone. At this point, there is no way of knowing when this will happen, Science Blog