The Chesapeake Bay’s hypoxic low-oxygen zone, also known as a “dead zone,” is expected to be 1.37 cubic miles, or about the volume of 2.3 million Olympic-size swimming pools.
While this forecast is still large, it is 10 percent lower than the annual long-term average measured since 1950. The anoxic portion of the zone, containing no oxygen, will be about 0.27 cubic miles in the early summer, growing to 0.38 cubic miles by late summer.
Low river flow and low nutrient loading of the Susquehanna River this spring is given as the reason for the slight decrease in the “dead zone.” The Susquehanna River is just one of 11 large rivers running into the bay.
Runoff from farmlands containing fertilizers and livestock waste have been the major source of nitrogen and phosphorus nutrients responsible for the annual dead zones in the Chesapeake Bay. Over the years, fish and shellfish have either left the oxygen-depleted water or died. This, in turn, has threatened the production of crabs and oysters, as well as other fisheries.
“These annual forecasts help to remind federal and state policymakers and the public that insufficient progress is being made to reduce the size of these low-oxygen regions,” said aquatic ecologist Don Scavia, director of the University of Michigan’s Graham Sustainability Institute.
The Chesapeake Bay – Multifunctional and precious resource
The Chesapeake Bay has been a major tourist attraction for people visiting Maryland and Virginia for years. With fishing, crabbing, swimming, boating, kayaking and sailing, it is important to the economies of both states. The bay is also known for its seafood production, especially its blue crabs, oysters, and clams.
By the middle of the 20th century, the bay supported over 9,000 full-time watermen. Today, though, there are fewer watermen working in the seafood industry. The waters of the Chesapeake Bay are less productive due to runoff and urban sprawl, mostly on the Western Shore, and farms, especially in the Susquehanna River watershed area on the Eastern shore.
There have been ongoing problems with over-harvesting and invasion of foreign species. To combat the nitrogen and phosphorus runoff, oyster farming has been a growing concern. Oysters are filter feeders. The Chesapeake Bay Program is using oysters to reduce the amount of nitrogen compounds entering the Chesapeake Bay.
“Forecasting how a major coastal ecosystem, the Chesapeake Bay, responds to decreasing nutrient pollution is a challenge due to year-to-year variations and natural lags,” said Donald Boesch, president of the University of Maryland Center for Environmental Science. “But we are heading in the right direction.”
Monitoring the bay is a full-time partnership between the U.S. Geological Service, NOAA, the Maryland Department of Natural Resources, and the Chesapeake Bay Program. Over 400 monitoring stations collect water quality data that tracks how nutrient loads change over time. This data is crucial to keeping the bay healthy, and it is an ongoing job.
