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 of course, the Chesapeake Bay.

Boston Harbor

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 shark Black sea bass

Fish in the Chesapeake Bay Large-mouthed bass fresh water fish that may come into the brackish areas 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. Bluefish Flounder 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 Common Waterweed

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 waters 2.fresh and salt water marshes 3.sandy beaches 4.mud and sand flats 5.rocky shores 6.river deltas 7.tidal pools 8.sea grass and kelp beds 9.wooded swamps 10.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 Benefits Estuaries 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?

Windows to the Universe team. Ecosystems. Boulder, CO: © University Corporation of Atmospheric Research (UCAR), © , 2000 The Regents of the University of Michigan, December 4, Online. Available: May 5, 2008.