Scientists expect that this year’s mid-summer Chesapeake Bay hypoxic low-oxygen zone or “dead zone” – an area of low to no oxygen that can kill fish and aquatic life – will be approximately 1.58 cubic miles, about the volume of 2.3 million Olympic-size swimming pools. This is close to the long-term average as measured since 1950.I would have thought, with our relatively mild winter, and the clean waters we've seen in the Bay this year, that the prediction would be better.
The anoxic portion of the zone, which contains no oxygen at all, is predicted to be 0.28 cubic miles in early summer, growing to 0.31 cubic miles by late summer – both of which are smaller than average. Low river flow and low nutrient loading from the Susquehanna and Potomac rivers this spring account for the smaller predicted size of the anoxic portion.
The Bay’s hypoxic and anoxic zones are caused by excess nutrient pollution, primarily from human activities such as agriculture and wastewater. The low oxygen levels are insufficient to support most marine life and habitats in near-bottom waters and threaten the Bay’s production of crabs, oysters and other fisheries.
The predicted “dead zone” size is based on models that forecast three of its features: midsummer low-oxygen hypoxic zone, early-summer oxygen-free anoxic zone, and late-summer oxygen-free anoxic zone. The models were developed by NOAA-sponsored researchers at the University of Maryland Center for Environmental Science and the University of Michigan . They rely on nutrient loading estimates from the U. S. Geological Survey.
Tuesday, June 14, 2016
"Dead Zone" Forecast for Bay Suggests Slight Improvement
Chesapeake Bay ‘dead zone’ to be average to slightly smaller