The Gulf of Mexico has an area of low to no oxygen in the water that can kill fish and other marine life. It is an annual event that is primarily caused by excess nutrient pollution from human activities in urban and agricultural areas throughout the Mississippi River watershed. When these excess nutrients reach the Gulf, they stimulate the overgrowth of algae, which eventually die and decompose, depleting the oxygen in the water as the algae sink to the bottom.
These low oxygen levels near the bottom of the Gulf cannot support most marine life. Some species – among them many fish, shrimp, and crabs – swim out of the area, but animals that can’t swim or move away are stressed or killed by the low oxygen. The dead zone in the Gulf occurs every summer.
A recent forecast for this summer’s dead zone predicts that the area of low or no oxygen will be approximate 6,700 square miles, which is roughly the size of Connecticut and Delaware combined. This is about 1,100 square miles smaller than last year’s dead zone and much less than the record of 8,776 square miles set in 2017. But it is still larger than the long-term average size of 5,387 square miles.
Making comparisons to the long-term average ignores the fact that the long-term average itself is unacceptable. The dead zone not only hurts marine life, but it also harms commercial and recreational fisheries and the communities they support. The actions that have been taken so far to reduce pollution in the Mississippi watershed are clearly not sufficient to drastically reduce the dead zone in the Gulf.
Photo, posted October 17, 2017, courtesy of NOAA’s National Ocean Service via Flickr.