NOAA-funded scientists expect a slightly above-average hypoxic zone in the Chesapeake Bay in 2014.
The forecast predicts a mid-summer low oxygen hypoxic zone of 1.97 cubic miles, an early-summer oxygen-free anoxic zone of 0.51 cubic miles, with the late-summer oxygen-free anoxic area predicted to be 0.32 cubic miles. Because of the shallow nature of large areas of the estuary the focus is on water volume or cubic miles.
The Chesapeake Bay prediction is based on models developed by NOAA-sponsored researchers at the University of Maryland Center for Environmental Science, University of Michigan, and relies on nutrient loading estimates from USGS.
USGS nutrient-loading estimates for the Chesapeake Bay are used in the hypoxia forecast. Data for the Chesapeake region is funded with a cooperative agreement between USGS and the Maryland Department of Natural Resources. USGS also operates real-time nitrate sensors the Chesapeake Bay watershed to track how nutrient conditions are changing over time.
USGS estimates that 44,000 metric tons of nitrogen entered the Chesapeake Bay from the Susquehanna and Potomac rivers between January and May of 2014, higher than the 36,600 metric tons delivered to the Bay during the same period in 2013.
Dead zones in the Chesapeake Bay threaten a multi-year effort to restore the water and habitat quality to enhance its production of crabs, oysters, and other important fisheries.
Hypoxic (very low oxygen) and anoxic (no oxygen) zones are caused by excessive nutrient pollution, primarily from human activities such as agriculture and wastewater, which results in insufficient oxygen to support most marine life and habitats in near-bottom waters.
Aspects of weather, including wind speed, wind direction, precipitation and temperature, also affect the size of dead zones.
“We are making progress at reducing the pollution in our nation’s waters that leads to ‘dead zones,’ but there is more work to be done,” said Kathryn D. Sullivan, Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator.
sources: NOAA, USGS