This is a map of estuaries in the Mid-Atlantic region of the U.S. eastern coast including the well-known Chesapeake Bay Estuary. Notice how the rivers get very wide as they get closer to the ocean? This is where the salt water of the ocean is mixing with the fresh water of the rivers.
Click on image for full size
Courtesy of the EPA.
An estuary is an unique environment where fresh water and salt water come together. Estuaries are found on the coast where a river or bay or other source of fresh water has access to the open sea. A good example of an estuary is a salt marsh that can be found close to the coast. Another example is when a river
feeds directly into the ocean.
The largest estuary in the United States is the Chesapeake Bay
estuary on the east coast of the U.S.
Estuaries are affected by the tides. So, there can be changes of salinity, temperature and other physical properties in an estuarial system which means the organisms there must be very tolerant to change. Even with that consideration, estuaries are among the most fertile places in the world. All kinds of plants and animals live there! When looking at estuaries, scientists quickly realized that these areas were extremely nutrient-rich because of sediment deposit of rivers, creeks or streams feeding into the salt water environment.
Unfortunately, estuaries haven't always been seen as valuable. In the past, they were seen as worthless and were used as dumps, or places for new land development (by filling in the marshy area!). In 1972, Congress created the National Estuarine Research Reserve System (NERRS) to establish, manage, and maintain estuary reserves, and to provide for their long-term stewardship.
Shop Windows to the Universe Science Store!
The Summer 2010 issue of The Earth Scientist
, available in our online store
, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.
You might also be interested in:
Rivers are very important to Earth because they are major forces that shape the landscape. Also, they provide transportation and water for drinking, washing and farming. Rivers can flow on land or underground...more
Have you ever walked along a beach at low tide? Maybe you've had the opportunity to explore the world the sea water revealed when the water receded? Everyone likes to look for uncovered sea shells or the...more
About 70% of the Earth is covered with water, and we find 97% of that water in the oceans. Everyone who has taken in a mouthful of ocean water while swimming knows that the ocean is really salty. All water...more
Sneeze into a pile of dust and the particles fly everywhere. Sneeze into a pile of rocks and they stay put. That’s because they have more mass. You need more force than a sneeze to move those rocks. Wind...more
Humans significantly alter the Earth. Big Idea 9.1 Human activities significantly change the rates of many of Earth’s surface processes. Humankind has become a geological agent that must be taken into...more
The Earth has one big ocean with many features. Fundamental Concept 1a. The ocean is the dominant physical feature on our planet Earth—covering approximately 70% of the planet’s surface. There is one ocean...more
An aquifer is the name for a layer of rock which is capable of holding a large amount of water. Some layers are better at holding water than others, for example a layer of sandstone can hold a good deal...more