Estuary Statistics

Estuaries have brackish water (a salty and fresh water combination), and a wide range of salinity levels.  Since no two estuaries are alike, salinty can range from 0.5 ppt to 35 ppt (ppt means parts per thousand).  The temperature, level, and salinity is constantly changing because they depend on the tide or weather, which is never the same from day to day.  Because of this, everything that lives in or around an estuary must be able to adapt very quickly to the changing estuarian environment.

Estuarian Animal Life

Many animals thrive in estuaries.  Estuaries have more life per square inch than Midwest farmland, which is saying a lot.  Some of the animals that live in estuaries are manatees, fish (salmon, etc), shellfish (shrimp, scallops, etc), oysters, filter feeders (horseshoe crabs, etc), predatory snails (Oyster Drills, whelks, etc), sponges, crabs, osprey, and other marine and shore birds.  As you can see, estuaries are teeming with life!

Estuarian Plant Life

All estuaries are home to many species of plants.  Mangroves, sea grasses, and pickleweed all thrive in estuaries and can adapt to its changing conditions very easily.  They provide food and shelter for many of the animals that live in the estuary, too.

Delta Estuaries

Delta Estuaries are formed when a river mouth is partially blocked by silt or sediment build-up.  They are found at river mouths where the freshwater river empties into salt water.  Some river mouths that have estuaries are the Nile River mouth and the Mississippi River mouth.

Fjords

Fjords are U-shaped valleys formed by glaciers.  Fjords are found in areas with lots of old glacier movement, like Northern Europe, Canada, and Alaska.  Here are some fjord diagrams.

Bar-Built Estuaries

Bar-Built Estuaries are formed when a shallow bay or lagoon is protected from the rough ocean by a sand bar or barrier island.  Bar-built estuaries are found along the Eastern Seaboard and the North American Gulf Coast.  Here are some diagrams of bar-built estuaries.

Tectonic Estuaries

Tectonic Estuaries are formed when land cracks or folds due to tectonic plate movement.  Tectonic estuaries are found along fault lines, like the San Francisco Bay area.  Here are some tectonic estuary diagrams.

Coastal Plain Estuaries

Coastal Plain Estuaries are formed when the sea level rises and salt water flows into an existing river valley.  Some examples of a coastal plain estuary are the Chesapeake Bay and the harbor in Charleston, South Carolina.  Here are some diagrams of a coastal plain estuary.

What is an Estuary?

An estuary is a body of water where freshwater meets saltwater.  There are five types of estuaries: coastal plain, tectonic, bar-built, fjord, and delta.