Restoring Estuaries: Chesapeake Bay Part Six, Issue 21 Restoring Estuaries: Chesapeake Bay

Objectives After reading the assigned chapter and reviewing the materials presented the students will be able to understand: What are the sources and impacts of pollution on Chesapeake Bay? What is the status of remediation efforts?

Background The Chesapeake Bay of the Susquehanna River is the nation’s largest and most productive estuary. The watershed’s 64,000 square mile area includes parts of six states, and the district of Columbia. The airshed measures 418,000 square miles, or roughly six and a half times the size of the Bay’s watershed.

Environmental Research on Chesapeake Bay In 1983, the U.S. Environmental Protection Agency (EPA) concluded that the Bay was seriously threatened by nutrient enrichment. The EPA also expressed concern regarding: The overharvesting of oysters, crabs, and fish. The 2,000 dams and other obstructions to fish passage. The toxic emissions entering the Bay, mainly from industrial and commercial sources. By 1991, the Bay’s once thriving oyster population had nearly disappeared. Bottom grasses provide oxygen for the water, and hiding places for juvenile fish, crab larvae, and many small animals. The decline of Bay grasses was caused by nutrient enrichment which caused algae to flourish blocking sunlight from bottom grasses. Without Bay grasses to replenish the depleted oxygen, the bottom becomes inhospitable to most animal life. By 1992, a ban on phosphate bearing detergents reduced phosphorous by 16%.

New Developments in Chesapeake Bay Research Recent research discovered that between 20 and 35 percent of nitrogen in Chesapeake Bay is from air pollution. A third of this air pollution is from cars, power plants, and farm fields in the watershed itself, but two-thirds is from power plant emissions in Ohio, Kentucky, Michigan, and other states as far away as Alabama. These nitrogen oxide pollutions also contribute to acid precipitation and respiratory problems in children and elderly people.

Pfiesteria and Manure An outbreak of Pfiesteria algae killed thousands of fish in tributaries of Chesapeake Bay in 1977. The outbreak seemed to be limited to streams that drained areas of Maryland with industrial sized chicken farms. These farms spread up to 800,000 tons of nutrient enriched chicken manure each year on fields, some immediately adjacent to streams. The federal government and Maryland proposed paying chicken growers to leave unplowed grass and vegetated buffer strips along streams that drained through their land. The plants would absorb nutrients in runoff, preventing them from contaminating the Bay.

Chesapeake 2000 and Bay Remediation Bay grass area had doubled since 1991. Almost 500 linear miles of forest had been restored between 1996 and 2000. The nitrogen declined 42 million pounds between 1985 and 1998. The phosphorous declined by 6 million pound per year. Between 1988 and 2000, 1032 miles of tributary streams were reopened to migratory fish passage.

Future Challenges Protection of forest and agricultural land from sprawl development. Further removal of nitrogen and phosphorous from sewage. Opening tributaries to fish passage by breaching dams or building fish ladders. Protecting the blue crab, a symbol of Chesapeake Bay threatened by overharvesting and pollution. Invasive species brought into the bay in the ballast water of ocean going cargo vessels.

Summary The Chesapeake Bay of the Susquehanna River is the nation’s largest and most productive estuary. The EPA expressed concern regarding: The overharvesting of oysters, crabs, and fish. The 2,000 dams and other obstructions to fish passage. The toxic emissions entering the Bay, mainly from industrial and commercial sources. The decline of Bay grasses was caused by nutrient enrichment which caused algae to flourish blocking sunlight from bottom grasses. Recent research discovered that between 20 and 35 percent of nitrogen in Chesapeake Bay is from air pollution. The federal government and Maryland proposed paying chicken growers to leave unplowed grass and vegetated buffer strips along streams that drained through their land. The plants would absorb nutrients in runoff, preventing them from contaminating the Bay.

Home Work 1. What was the cause of decline of Bay grasses? 2. What was the solution to preventing chicken manure runoff in tributaries of Chesapeake Bay?