Last weekend, media outlets reported a NOAA announcement that this year's Gulf of Mexico low oxygen 'dead zone' is the fourth smallest since 1985. A severe drought baking the nation's midsection is responsible for less nutrient-laden Mississippi River water that triggers the annual phenomenon. By contrast, last year's floods resulted in low oxygen over an area more than twice as large as this year.
This confirms a strong relationship exists between the volume of freshwater and nutrients discharged into the Gulf and the zone's size. Dead zones form when nutrients washed from land stimulate vast plumes of algae. As they sink, bacteria that feed on the algae consume most of the life-giving oxygen in deeper water, forcing creatures living there to flee or die.
The underlying research by the Louisiana Universities Marine Consortium was made possible by funding from the National Centers for Coastal Ocean Science."The issue of nutrient overload, of both nitrogen and phosphorus, remains a critical issue for the health of water bodies within the Mississippi River Basin and in the northern Gulf of Mexico,'' according to the consortium.
Press release:NOAA scientists: Midwest drought brings fourth smallest Gulf of Mexico 'Dead Zone' since 1985