The Chesapeake Bay is the largest estuary in the United States. The Bay sustains more than 3,600 species of plants, fish and animals, including 348 species of finfish, 173 species of shellfish and over 2,700 plant species. Every year, one million waterfowl winter in the Bay region. The Chesapeake is a commercial and recreational resource for the more than 16 million people who live in its watershed and produces about 500 million pounds of seafood per year.
Waters drains into the Chesapeake Bay from the District of Columbia, Maryland, Virginia, Pennsylvania, Delaware, West Virginia, Delaware, and New York. In the 64,000-square-mile watershed, the Bay (and the rivers and streams that feed into it) is affected by everything people do — including the use of cars, fertilizers, pesticides, toilets, water and electricity. The pollution we send into the Bay causes it to have “dead zones”—areas that become devoid of oxygen during the Chesapeake's hot summer months and cannot support most forms of life. Excess nutrients (nitrogen and phosphorus) from agriculture, air deposition, septic systems and sewage treatment plants, and runoff from lawns, gardens and paved surfaces reach the Bay and fuel the growth of phytoplankton, or algae. While phytoplankton form the base of the Bay's food chain, the amount of nutrients now entering the Bay is overwhelming the system. Oysters and other filter feeders can't consume all the phytoplankton in the water. Unconsumed phytoplankton sink to the bottom of the Bay and are decomposed by bacteria in a process that depletes the water of oxygen. The decomposing phytoplankton, combined with higher water temperatures, can cause large swaths of the deepest parts of the Bay's mainstem to have little or no oxygen to support marine life. The Chesapeake is not the only Bay with dead zones. The Gulf of Mexico also suffers from dead zones for similar reasons and this phenomenon is on the rise world wide. A recent preliminary report from the International Programme on the State of the Ocean (IPSO) examined the combined impact of all of the stressors currently affecting the oceans and listed dead zones, along with ocean warming and acidification, as one of the top three historical factors contributing to mass extinctions. The panel warns that the combination of these factors will inevitably lead to mass extinctions if conditions are not mitigated. For example, flooding in the Mississippi River during the spring of 2011 is predicted to cause the largest dead zone ever recorded in the Gulf of Mexico.
The Chesapeake Bay was the first estuary in the nation to be targeted for restoration as an integrated watershed and ecosystem.
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