1. Chesapeake Bay

2. Chesapeake Bay History
Formed 12,000 years ago when the last great ice sheet melted, filling the ancient Susquehanna River.
Our current coastline is approx. 70 miles more inland than the original shoreline.
The FIRST incarnation of the bay area was created by a meteorite.
The PRESENT day Chesapeake Bay was formed from the last ice age.

3. Chesapeake Bay Statistics
The largest estuary in N. America.(2500 sq mi)
200 mi. long and 30 mi. wide
Over 15 million live in the Chesapeake’s watershed, which spreads across six states: Virginia, West Virginia, Maryland, Delaware, Pennsylvania, New York and Washington D.C principle rivers
400 lesser streams and creeks
Has more than 4,600 miles of tidal shoreline
The bay hosts nearly 350 species of finfish and almost 175 species of shellfish.

4. The Watershed of the Bay
Def.-An area of land that is drained by a river or other body of water.

5. Six states make up the Ches. Bay watershed:
1. Virginia
2. New York
3. Pennsylvania
4. Maryland
5. Delaware
6. West Virginia

6. Main Rivers of the Bay There are 5 main rivers of the shore:
1. James River
2. York River
3. Rappahannock River
4. Potomac River
5. Susquehanna River

7. The Rivers of the Bay
Rivers on the western shore are generally larger than those on the eastern shore.
The eastern shore is characterized by marshlands and support a variety of waterfowl.
52% of the bay’s freshwater comes from the Susquehanna River (main river of the bay)

8. Depth of the Bay The bay is very shallow.
The average depth is only 20 feet.
The deepest spot is near Annapolis, MD and is approximately 180 ft. deep.
The bay’s world-famous oyster and soft- shelled clam harvests are due to the amount of suitable shallow water of the bay.

9. Seasons of the Bay: Spring
A resurgence of activity; migratory species such as fish and crabs move toward the warming shallows from deeper parts of the ocean.
Shads and herrings move upstream to spawn.
Invertebrates begin to grow and reproduce.

10. Seasons: Spring to Summer
Many fish enter the bay to feed on the abundant schools of smaller fishes such as anchovies and menhaden.

11. Seasons: Fall and Winter
Species begin to migrate out of the bay.
Activity and growth decline.
In winter months, many animals seek the deeper areas of the bay for warmth.

12. How Salty is the Water?
Salinity increases gradually downstream (towards the ocean).
Midway downstream it is 12 ppt (about ½ that of the ocean).
Salinity also increases from the surface to the bottom. (2-3 ppt saltier)
Salty water is heavier so it sinks below the less salty water.

13. Zones of the Bay Zone 1 – tidal freshwater Zone 2
– slightly brackish to moderately salty
- upper zone is 1-10 ppt
lower zone is ppt
Zone 3
– salinities 18ppt to ocean salinities of 30+ ppt
- many oceanic animals live here as well as estuarine species

14. Salinity Determines…….
No matter what the habitat – a beach, marsh, intertidal flat – SALINITY determines the kind of species that live there.