1. The Chesapeake Bay’s “Dead Zone” Created by Jeff DeHart October 2007

2. The Chesapeake Bay: A Little Bit of Background The Chesapeake Bay is North America's largest estuary (an area where fresh and salt water mix) and the world's third largest. The Chesapeake Bay is North America's largest estuary (an area where fresh and salt water mix) and the world's third largest.

3. The Chesapeake Bay watershed encompasses parts of six states: Delaware, Maryland, New York, Pennsylvania, Virginia, and West Virginia as well as the District of Columbia. The Chesapeake Bay watershed encompasses parts of six states: Delaware, Maryland, New York, Pennsylvania, Virginia, and West Virginia as well as the District of Columbia. The watershed covers 64,000 square miles and is home to about 17 million people. The population is expected to increase to more than 18 million residents by 2020. The watershed covers 64,000 square miles and is home to about 17 million people. The population is expected to increase to more than 18 million residents by 2020.

4. The History of the Bay The Chesapeake Bay was formed about 12,000 years ago when glaciers melted and flooded the Susquehanna River valley. The Chesapeake Bay was formed about 12,000 years ago when glaciers melted and flooded the Susquehanna River valley. The archeological record shows that humans have lived in the watershed since 8,000 B.C. Mammoth, mastodon, bison, elk, camel, horse, and peccary roamed the Chesapeake watershed during this era. The archeological record shows that humans have lived in the watershed since 8,000 B.C. Mammoth, mastodon, bison, elk, camel, horse, and peccary roamed the Chesapeake watershed during this era. The name Chesapeake is derived from the Native American word "Tschiswapeki" meaning "great shell fish bay." The name Chesapeake is derived from the Native American word "Tschiswapeki" meaning "great shell fish bay."

5. Facts About the Bay The Chesapeake Bay watershed supports more 3,600 species of plant and animal life, including about 350 species of fish. The Chesapeake Bay watershed supports more 3,600 species of plant and animal life, including about 350 species of fish.

6. Facts continued… From north to south, the Bay is roughly 200 miles long. From north to south, the Bay is roughly 200 miles long. The narrowest part of the Bay is 3.4 miles at Aberdeen, Maryland. It is four miles wide near Annapolis, Maryland, and it is the widest near the mouth of the Potomac River - 35 miles. The narrowest part of the Bay is 3.4 miles at Aberdeen, Maryland. It is four miles wide near Annapolis, Maryland, and it is the widest near the mouth of the Potomac River - 35 miles. The Bay has an average depth of 21 feet. There are a few deep holes that are more than 170-feet deep, including "The Hole" that is 174 feet deep and located off Bloody Point, Maryland. The Bay has an average depth of 21 feet. There are a few deep holes that are more than 170-feet deep, including "The Hole" that is 174 feet deep and located off Bloody Point, Maryland. The Bay has more than 11,600 miles of shoreline, including all tidal wetlands and islands. That's more shoreline than the entire West coast of the United States. The vast majority of shoreline is privately owned. The Bay has more than 11,600 miles of shoreline, including all tidal wetlands and islands. That's more shoreline than the entire West coast of the United States. The vast majority of shoreline is privately owned.

7. The Chesapeake Bay is a valuable resource for us humans as well! The Chesapeake Bay is a valuable resource for us humans as well! But there is a slight problem occurring in the bay… But there is a slight problem occurring in the bay…

8. WARNING! You are about to enter… The DEAD ZONE

9. Imagine what life would be like, if for months at a time the air we breathe contained very little oxygen… or NO oxygen at all!

10. The Chesapeake Bay’s “dead zone,” which stretches for hundreds of square miles during the summer, has too little oxygen to support a healthy ecosystem.

11. The dead zone affects approximately 40% of the Chesapeake Bay’s main stem. The dead zone affects approximately 40% of the Chesapeake Bay’s main stem. Starting at the Patapsco River near Baltimore, the dead zones extends more than 100 miles south to York River, near Hampton Roads, Virginia. Starting at the Patapsco River near Baltimore, the dead zones extends more than 100 miles south to York River, near Hampton Roads, Virginia.

12. Low dissolved oxygen (DO) levels, called hypoxia, can affect the growth and reproduction as well as the health of the Chesapeake’s living resources. Low dissolved oxygen (DO) levels, called hypoxia, can affect the growth and reproduction as well as the health of the Chesapeake’s living resources. Some areas have no oxygen at all and are called anoxic. Anoxic waters will kill most aquatic animals. Some areas have no oxygen at all and are called anoxic. Anoxic waters will kill most aquatic animals.

13. Like animals on land, nearly all of the Chesapeake Bay’s aquatic life depend on oxygen to survive, to perch and striped bass above to perch and striped bass above and underwater grasses in between from worms and crabs on the bottom

15. Cause and Effect Low dissolved oxygen levels in the Bay are a result of nutrient pollution, mainly nitrogen and phosphorous. Low dissolved oxygen levels in the Bay are a result of nutrient pollution, mainly nitrogen and phosphorous. Nitrogen and phosphorous wash into the water from fertilized farm fields, gardens, and lawns. Nitrogen and phosphorous wash into the water from fertilized farm fields, gardens, and lawns. Chemical fertilizers from factories and automobile exhaust bond with water droplets in clouds and fall back into the Bay with rain showers. Chemical fertilizers from factories and automobile exhaust bond with water droplets in clouds and fall back into the Bay with rain showers. Human sewage from sewage treatment plants also enters the Bay, adding more nutrients. Human sewage from sewage treatment plants also enters the Bay, adding more nutrients.

16. Cause and Effect continued… This nutrient pollution in the Bay causes huge algal blooms (algae). This nutrient pollution in the Bay causes huge algal blooms (algae). When this algae dies, it sinks to the bottom of the Bay and then starts to decompose. During decomposition, bacteria work overtime to eat the decaying algae, using up the oxygen supply. When this algae dies, it sinks to the bottom of the Bay and then starts to decompose. During decomposition, bacteria work overtime to eat the decaying algae, using up the oxygen supply. This decomposition process removes oxygen from the water, making it extremely hard for organisms to survive. This decomposition process removes oxygen from the water, making it extremely hard for organisms to survive.

17. August, 2007 Algal bloom near Hampton, VA June, 2007 Close up of the leading edge of a red algal bloom at the mouth of the Potomac River

19. The Problem in the Mainstem In the deep waters of the Chesapeake Bay, the decomposition of algal blooms causes anoxia or hypoxia during much of the summer. In the deep waters of the Chesapeake Bay, the decomposition of algal blooms causes anoxia or hypoxia during much of the summer. The bottom areas of the Bay suffer from these low dissolved oxygen levels for roughly 10 months out of the year. The bottom areas of the Bay suffer from these low dissolved oxygen levels for roughly 10 months out of the year. The dead zone can also reach into shallow waters, hurting habitat and forcing fish and crabs to leave the area. Many fish and crabs are unable to leave these areas and have died as a result. The dead zone can also reach into shallow waters, hurting habitat and forcing fish and crabs to leave the area. Many fish and crabs are unable to leave these areas and have died as a result.

20. June, 2007 Fish Kill near Weems Creek, MD September, 2007 Fish Kill in South River, MD

21. What can we do? The best thing we can do to help solve the low dissolved oxygen problem is to address nutrient pollution of the Bay. The best thing we can do to help solve the low dissolved oxygen problem is to address nutrient pollution of the Bay. We need to reduce nitrogen pollution from farmland runoff, vehicles and power plants and sewage treatment plants. We need to reduce nitrogen pollution from farmland runoff, vehicles and power plants and sewage treatment plants. Restoration of the Bay’s natural defense systems such as forestlands, wetlands, oysters, and underwater grasses will help the Bay protect itself. These natural features of the Bay will help to filter nutrients and sediment from bay water and rainfall. Restoration of the Bay’s natural defense systems such as forestlands, wetlands, oysters, and underwater grasses will help the Bay protect itself. These natural features of the Bay will help to filter nutrients and sediment from bay water and rainfall. Spread the word about the importance of the Chesapeake Bay! Spread the word about the importance of the Chesapeake Bay!

22. Images courtesy of: www.nationalgeographic.com www.cbf.org www.fws.gov www.audubon.org www.outdooralabama.com www.dnr.metrokc.gov www.olesouthusa.com www.mcintoshcounty.com www.visitannapolis.com www.bobrooks.com