Marine dead zones refer to areas of the ocean which are too low in oxygen to support life. In the Gulf of Mexico, runoff from agricultural operations, mostly nitrogen and phosphorus, travels down the Mississippi and Atchafalaya rivers, contributing to an overgrowth of algae and a widening dead zone in the Gulf. Curbing the use of fertilizers in agriculture is one way to slow the growth of dead zones, but a new study from the University of Waterloo and the University of Illinois Chicago finds that pairing that strategy with wetlands protection could offer enormous marine health benefits.
The researchers note that fertilizer reduction and wetlands conservation, while always beneficial, don’t necessarily correlate with areas where runoff is highest. However, a 10 percent increase in wetlands in the US, focused in heavily farmed areas, could remove up to 40 times more nitrogen. These heavily farmed areas include the Mississippi Basin, where a 22 percent increase in wetlands would yield a “54 percent decrease in nitrogen loading to the Gulf of Mexico.”
Wetlands restoration isn’t cheap一the researchers estimate that a 10 percent increase would cost $3.3 billion annually一but the dead zone in the Gulf of Mexico now measures 5,400 square miles and compared to the destruction of profitable fisheries and critical marine habitat, many feel it is a small price to pay. Plus, wetlands restoration offers numerous other ecological benefits including habitat conservation, flood prevention, carbon sequestration, and improved water quality.
Source study: Nature – Maximizing US nitrate removal through wetland protection and restoration