The Estuaries: As we discussed before, the estuaries are complex. They are neither freshwater nor saltwater but make the part of marine biome. Estuaries are the water bodies formed where rivers and streams blend with the ocean. This means that they are not as salty as ocean and not as fresh as the rivers and streams. The areas of estuaries include river mouths, lagoons, salt marshes, and bays.
Estuaries are of different shapes and sizes. Some people call the estuaries the “between-land” as the estuaries are not exactly land and not perfectly water. The largest estuary in the world, due to its poor definition, is difficult to determine. However, most experts believe that St. Lawrence River, which connects the Great Lakes to the Atlantic Ocean, is the largest on the Earth.
The estuaries are of four in kind. They are coastal plain estuaries, tectonic estuaries, bar-built estuaries, and fjord estuaries.
Coastal plain estuaries are formed as a result of sea level rises. When the sea level rises and falls into an existing river valley, these estuaries take birth. On the other hand, tectonic estuaries are formed due to the tectonic activities such as movement of earth or rifting of the earth’s crust. However, bar-built estuaries are formed as result of a sandbar protecting a lagoon or bay from the ocean. The last, fjord estuaries, are created as glaciers sculpt out a deep valley for the ocean to fill this valley.
There are many organisms that adapted to live in the estuaries. However, the major challenges that the organisms face are the fluctuating salt content in the water and sedimentation. In spite of the challenges offered by the estuaries, there are many different kinds of animals and plants making these estuaries their home.