estuaries where fresh water meets salt water. estuary defined an estuary is a partially enclosed...
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Estuaries
Where Fresh Water Meets Salt Water
Estuary Defined
An estuary is a partially enclosed body of water formed where fresh water from rivers and streams flows into a bay or ocean, mixing with the salt water.
Estuaries come in all shapes and sizes and go by different names.Estuaries can also be called bays,
lagoons, harbors, inlets, or sounds. Sometimes these water bodies by those names are not necessarily estuaries. The defining feature of an estuary is the mixing of fresh and salt water, not the name!
What are some familiar estuaries?
Some familiar estuaries include San Francisco Bay, Puget Sound,Boston Harbor, Tampa Bay, and
ofcourse, the Chesapeake Bay.
Tampa Bay
Puget Sound
Chesapeake Bay Estuary
The Chesapeake Bay is the largest of about 130 estuaries in the United States.
The Chesapeake Bay is one of the most productive estuaries in America.
Chesapeake Bay Characteristics
The bay stretches from Havre De Grace, MD to Norfolk, VA.
The bay is about 200 miles long, but along with its tributaries has a shoreline that measures approximately 11,684 miles in total.
The Chesapeake Bay is shallow, as its average depth is only 21 feet.
The deepest point is 174 feet deep located off of Annapolis, called “The Hole.”
Quick Fact:Tidewater is water that is affected by the ebb and flow of tides.
Living Organisms need Special Adaptations to Live in an Estuary
The salinity level (amount of salt in the water) is constantly changing!
1. If rivers bring in extra water, during periods of flooding, the salinity of the estuary will be reduced.
2. If drought causes the flow of freshwater to decrease, then the salinity of the estuary may be increased.
What type of organisms live an estuary?The tidal, sheltered
waters of estuaries support unique communities of plants and animals, specifically adapted to life where the salinity (amount of salt) constantly changes as freshwater mixes with salt water.
Variety of Estuarine Animals
Shore birds, fish, crabs and lobsters, marine mammals, clams and other shellfish, marine worms, sea birds, and reptiles are just some of the animals that make their homes in and around estuaries.
Animals in an Estuary
Fish in the Chesapeake Bay: These fish come from the ocean to feed in the lower, saltier areas
Sandbar sharkBlack sea bass
Fish in the Chesapeake Bay
Large-mouthed bassfresh water fish that may come into the brackishareas of the bay to feed.
These fish stay all year long – tolerate changes in salinity
White perch Striped Bass(rockfish)
These fish stay migrate because of changes in salinity or temperature.
BluefishFlounder
SpotCroaker
Other fish in the Bay
Spade Fish
Shad
Sea horse
Menhaden
Bay Grasses Add Oxygen to the Water and Habitats for Animals
Eel Grass CommonWaterweed
Why are Estuaries Important?
Estuaries are critical for the survival of many species.
They provide ideal spots for migratory birds to rest and refuel during their journeys.
Many fish and shellfish rely on the sheltered waters of estuaries as protective places to spawn. Estuaries are called the “Nurseries of the Seas.”
Migratory Birds
Estuaries Provide a Variety of Habitats
1. shallow waters2. fresh and salt
water marshes3. sandy beaches4. mud and sand
flats5. rocky shores
6. river deltas7. tidal pools8. sea grass and
kelp beds9. wooded
swamps10.oyster reefs
Estuaries are Important for Humans
Cultural benefits include recreation, scientific knowledge, and education.
Boating, fishing, swimming, surfing, and bird watching are just a few of the numerous recreational activities people enjoy.
Importance to Humans, continued.
Scientific knowledge and education: As transition zones, estuaries are
invaluable laboratories for scientists and students, providing countless lessons in biology, geology, chemistry, physics, history and culture.
Economic benefits include tourism, fisheries, and other commercial activities that thrive on the wealth of natural resources.
The protected coastal waters provide harbors and ports vital for shipping, transportation, and industry.
Measuring Economic BenefitsEstuaries provide habitat for 75% of
America’s commercial fish catch.Estuaries provide more than 28
million jobs.The average American Spends 10
recreational days on the coast of an estuary each year.
Health of Estuaries
Unfortunately, an increase in concentration of people near estuaries is upsetting the natural balance of estuarine ecosystems.
People can Harm Estuaries
Channels are dredged, which causes sediment to get in the estuary and cause higher turbidity.
People Harm Estuaries…continued
Shorelines are reconstructed to make room for housing and agricultural needs by filling marshes and wetlands.
People Harm Estuaries, Continued
Water is polluted and recreation creates excess sediments.
“Over fishing” fish, crabs and shellfish affect the complex food web of the estuary.
The Following can Occur in an Unhealthy Estuary:
Fish kills, unsafe drinking water, closing of
beaches and shellfish beds, harmful algal
blooms , unproductive fisheries, loss of
habitat and aquatic vegetation disappears.
Excess Nutrients Cause Algae Blooms:
What do Estuaries look like?
What do Estuaries look like?
What do Estuaries look like?
What do Estuaries look like?
• Windows to the Universe team. Ecosystems. Boulder, CO: ©2000-04 University Corporation of Atmospheric Research (UCAR), ©1995-1999, 2000 The Regents of the University of Michigan, December 4, 2002. Online. Available: http://www.windows.ucar.edu . May 5, 2008.