. Chesapeake as an Estuary • An estuary is a semi-enclosed body of water that has a free connection with the sea
Chesapeake as an Estuary • Estuaries have more food for organisms, but the organisms usually have to deal with large temperature and salinity changes, high silt content and pollution.
Why do you think high silt would be a problem for marine organisms? • Hint How does this organism get its food?
Many marine organisms are filter feeders so silt can be a major problem.
Estuaries are regions of transition and sharp gradients. Estuaries support fauna recruited mostly from the sea
The number of species in an estuary is greatly reduced, but the number of individuals is large. What does that mean? Can you explain that last statement?
The Answer • For those organisms that can survive the problems of the estuary, there is a great deal of food.
The Answer • These organisms tend to be in large numbers.
Estuary Types • The Chesapeake Bay is a drowned river valley. This is the most common type of estuary. It was formed during the last ice age some 12,000 – 18,000 years ago.
Estuary Types • The Chesapeake Bay is a drowned river valley. This is the most common type of estuary. It was formed during the last ice age some 12,000 – 18,000 years ago. • There are other types of estuaries. Can you name any of them?
Bar-Built Estuaries • These are found where sand bars and barrier islands form.
Bar-Built Estuaries • The shallow water behind these barrier islands forms low salinity estuaries.
Tectonic Estuaries • These estuaries form where land sank or subsided.
Tectonic Estuaries • A good example of this type of estuary is San Francisco Bay.
Fjords! • Fjords were created when retreating glaciers cut deep in the earth.
Fjords! • Where in the United States might we find fjords?
The bay is shallow. Can you guess its average depth? • 106 ft. • 56 ft • 32 ft. • 21 ft. • 14ft. • 9ft.
THE ANSWER! • 21 feet is the correct answer. The deepest spot in the bay is 174 feet near Annapolis Md.
A watershed is the drainage area for the bay. • Can you name the 6 states that make up the watershed of the Chesapeake Bay?
Virginia Maryland West Virginia Delaware New York Pennsylvania
Can you name the 5 major rivers that flow into the bay? • From South to North • James • York • Rappahannock • Potomac • Susquehanna
Which of those 5 rivers contributes the most fresh water to the bay? • The Susquehanna River provides about 50% of the fresh water coming into the Bay. • The river empties an average of 19 million gallons of water per minute.
Can you name a mammal that is named after the Bay? • Think you know? • The Chesapeake Bay Retriever
The Bay area is home to over 15,000,000 people! • About 50,000 commercial vessels enter the Bay each year.
The Bay area is home to over 15,000,000 people! • All these people and activities put a strain on the Bay ecology.
Bay Organisms • The Bay is home to over 3600 living organisms!
Marsh Dwellers • Marsh dwellers are located in and around marshes. They include small fish, birds, and marsh grasses.
SAV Communities • Submerged Aquatic Vegetation Communities are important for many reasons. They include ducks, crabs, and eelgrass.
Plankton Community • The plankton community includes the drifters of the Bay.
Plankton Community • It includes phytoplankton, bacteria, and zooplankton.
Benthic Communities • Benthic refers to the bottom of the Bay. Benthic organisms include oysters, clams, barnacles, and mud crabs.
Nekton Communities • Nekton refers to the swimmers of the Bay.
Nekton Communities • Croaker, Spot, and menhaden use shallow water in the Bay as a nursery