National Oceanic and Atmospheric Administration (NOAA) funded researchers at University of Michigan, Louisiana State University, and the Louisiana Universities Marine Consortium predict this season’s Gulf “dead zone” could be one of the largest ever experienced.
Interestingly, another NOAA-funded prediction by the University of Maryland Center for Environmental Science (MCES) and the University of Michigan, estimates the “dead zone” in the Chesapeake Bay region will be smaller as compared to historical averages.
NOAA’s National Ocean Service defines a “dead zone” as a more common term for hypoxia, which refers to a reduced level of oxygen in the water. Although hypoxia can occur naturally, excess nutrients that run off land or are piped as wastewater into rivers and coasts can stimulate an overgrowth of algae. As the algae sink and decompose in the water, the process consumes oxygen and depletes the supply available to healthy marine life.
According to University of Maryland Professor Raghu Murtugudde, the amount of snowmelt and storm run-off throughout the year will impact the size of a dead zone, since strong stream flows and increased levels of run-off will deposit more nutrients into the body of water.
“Since the winter was mild and there was not much snowfall, the snow melt and the streamflows will be not very strong, so nutrient and sediment loading will be small,” Murtugudde, former executive director of the Chesapeake Bay Forecasting System (CBFS), said of the Chesapeake Bay.
In terms of the Gulf of Mexico, Murtugudde said: “floods on the Mississippi flood plains and the massive snowfalls in the aftermath of Hurricane Sandy are likely to produce excessive dead zones, because of the excess nutrients and phytoplankton blooms.”
Researchers have confirmed that stream flows for the Mississippi and Atchafalaya Rivers were more intense than usual for the month of May, resulting in increased amounts of nutrients being deposited in the Gulf.
Current Gulf “dead zone” forecast projections are based on the assumption of no significant tropical storm activity in a two-week period preceding or during the official survey cruise, scheduled for July 25 – August 3, 2013.
The actual extent of the Gulf’s 2013 hypoxia won’t be confirmed until results from the official cruise are analyzed.
