13 Fun Facts About Estuaries: Learn How They Protect Natural Resources

Estuaries are sites where the saltwater of the seas meets the freshwater of rivers.

Estuaries can be the point of the meeting of one river with a sea, or where several rivers converge into a larger water body. Either way, the ecosystems formed therein are fascinating.

There are several types of estuaries, depending on the ratios of saltwater and freshwater, as well as the geological aspects.

In any case, each type of estuary comes with its own set of boons that you must know in order to be a responsible and conscious citizen. Since estuaries attract many tourists throughout the year and are sites of economic activities, they are highly threatened ecosystems.

Keep reading to learn how you can be conscious the next time you visit an estuary!

What is an estuary?

You may have heard of an estuary and the beautiful, self-sustaining ecosystem that functions within it. Estuaries are found all over the world and their protected coastal waters are great for human settlement as well.

This is one of the reasons why many settlements across the globe are formed near estuaries. They form great sites for agricultural and economic growth, due to the highly potent soil and the productive ecosystems which provide shelter and food to many species of invertebrates and fish.

An estuary is basically where a river or multiple rivers meet with an ocean. At the point of their conjunction, freshwater rivers mix with the salty or saline water of seas and oceans in order to create what we call brackish water.

There are several types of estuaries based on the mode of formation as well as the quality of water found in it. The speed and velocity of the ocean waves as well as the flow of the rivers are factors that affect estuaries and the water type that is found in them.

Estuarine ecosystems support the life of many seagrasses, phytoplanktons, marine organisms as well as invertebrates. The abundance of aquatic life in estuaries is one of the reasons why many people find themselves going to such sites for recreational purposes or sport fishing.

There are several types of estuaries such as fjords, coastal plain estuaries, tectonic estuaries, and bar-built estuaries. The classification of estuaries can be made on the basis of their shape, the reason for their formation, the ratio of saltwater to freshwater found in them as well as the speed at which water flows into them.

Coastal plain estuaries are formed when the gaps and river valleys are filled with water due to rising sea levels that were created due to glacial activity. When the sea levels rise more in comparison to the land, water rushes into the valley following a simple rule in physics.

Hence, this type of estuary is also known as a river valley estuary. For example, we can very well imagine that when glaciers of the Ice Age melted, they left deep indentations in the ground, that were to be named river valleys later.

As the sea levels rose after the melting of the huge chunks of ice, water rushed into the cavity on the land in order to fill it. The same phenomenon is the reason behind the formation of the Chesapeake Bay.

Fjords are similar in nature, although, they were formed due to the deepening of the existing river valleys after the ice melted away in Ice Age. The deepened river valleys then attracted the risen seawater levels, creating estuaries where there is a mixture of fresh water and saltwater.

These estuaries are typically U-shaped and have rocky bottoms. The sills along the sides of the estuaries were presumably due to glacial activity. Fjords also have a steep valley due to the same factor, which is absent in coastal plain estuaries.

Tectonic estuaries, as the name suggests, are created due to the movement of the tectonic plates. In simple terms, tectonic plates lie beneath the surface of the land and are in constant motion.

When two of such plates collide with each other, we feel jerks and tremors, which are known as earthquakes. Tectonic estuaries are also the products of such tectonic movements and were formed due to various methods such as faulting, volcanoes, and landslides.

Faulting refers to the creation of a crack on the surface of the Earth, big enough for large amounts of water to settle. Volcanic activity, as well as landslides, also contribute towards the creation of craters that can then become the meeting-point of rivers and oceans.

The inundation of the Sacramento and San Joaquin rivers is also a product of tectonic activities.

Bar-built estuaries, on the other hand, are very famous. They are sites for the building of coastal counties. If you love beaches but would rather not have the constant ebb and flow of waves to distract you, the site of a bar-built estuary might be best suited for you.

This is because, at such sites, the estuary itself is sheltered from the sea through sand spits or barrier islands.

The formation of bar-built estuaries or lagoons is basically because of the fact that at such sites, the pace at which the sediment formation took place was at par with that of the rise of the seawater levels, giving rise to sandy beaches.

Such coastal areas have many economic benefits due to the simple fact that people enjoy hosting picnics and also take part in sport fishing in bar-built estuaries.

The Purpose Of An Estuary

Depending on the type and the mode of formation of the river deltas, these water bodies can either be freshwater estuaries, mangrove forests, or salt marshes.

While the nature of all of these types of estuaries is quite different, what remains constant is the fact that all estuaries provide benefits to estuarine plants and marine life. Estuarine habitats are rich in fertile soil and the water is rich in nutrients.

The mangrove forests that form in brackish water act as a natural buffer zone and help in the filtration process of the water. As water flows through such a natural environment, there is a high degree of sediment formation.

This creates a natural balance and helps in the maintenance of water quality in the best and most sustainable way possible. However, this should not motivate you to think that the water that is filtered out of mangrove forests is fit for consumption!

Estuaries and river deltas are great sites for the settlement of human civilizations. In addition to providing the best possible environment for many marine organisms, they also provide protection against the strong tides and floodwaters of the sea.

Swamps and mangrove forests are great natural buffers since they slow down the flow of water and help in protecting human civilizations from possibly dangerous tidal pools.

The estuaries also have great economic value. Understandably, estuaries have clear water and great marine life, which is sure to attract many fishing enthusiasts. The fact that many of the world's largest economies are at places near estuaries is no coincidence.

A huge part of the economy of any state or nation is the number of tourist attractions it can provide. The sandy beaches and the availability of ample fish such as flounders that are found in estuaries are factors that attract people.

Picture this, you have an ice cream parlor near an estuary beach where people are constantly coming in to get some relief from the sun. The monetary value of an estuary is unbelievable!

Estuaries also help in the building of ports vital to the economy of a nation. Trade and commerce are sure to thrive when there are nice estuaries surrounding a nation due to the sheer amount of ease that they bring to the process.

Many people around the world also work at estuarine watersheds, adding a huge deal towards the economic stability of the nation.

It is because of these reasons that estuaries should be protected.

Famous Estuaries

There are many prominent and famous estuaries in the world, such as the Chesapeake Bay in the United States, which is a large estuary. The San Francisco Bay, located in the United States is also famous. It is situated in the state of California. The Delaware Bay of the United States of America is also a favorite tourist attraction.

The Thames Estuary towards the southeastern region of Great Britain is one of the most prominent economic centers. The Severn Estuary is located in the southwestern regions of Great Britain and is a drowned river valley estuary.

Human settlements along these water bodies can be quite harmful to marine life. The degradation of land affects the estuary. Depletion of sand flats and failing septic tanks are factors that threaten the most important estuaries around the world.

The release of untreated sewage threatens life in the coastal areas and if it gets released in the salty ocean water, it can lead to lasting adverse effects. The ocean waves often bring the pollutants back to the rocky shores and sandy beaches, which is never a welcome sight.

Prominent Plant And Animal Species In Estuaries

Since estuaries are sites where a river meets with an ocean, it is a great site for the fish and other animal life to thrive. Estuaries are also sites where migratory birds nest since it allows them to have constant access to fish and invertebrates to munch on.

Estuaries provide animals with shelter as well as food. For example, a juvenile fish in a mangrove forest or swamp is sure to feel safe due to the inconvenience that any predator would have to face in order to spot and kill it.

The natural buffers in the form of swamps and mangroves also protect upland habitats for fish and other organisms as well as plants.

Estuaries allow the penetration of water through to the very bottom of the water body. Hence, such places support the growth of many phytoplanktons as well as salt marsh grasses. This, in turn, is one of the factors which is crucial for the fish that breed on such grounds.

Phyto-planktons and other marine plants in salt marshes not only provide a hiding place for eggs and baby fish but also act as a source of nutrition for marine life.

The rocky shores are great for some animals. Estuaries also have oyster reefs and great deposits of mussels and clams, which are harvested by humans at a large scale.

Some of the prominent fishes that could be spotted at estuaries are salmon and eels. Salmons spend the middle portions of their lives in oceans. However, when they are ready for spawning, they move towards freshwater estuaries.

The juvenile fish remain in such estuaries for a while till they achieve maturity. Such water bodies are great for them to be protected against apex predators and also provide them with ample nutrition.

Predators such as crocodiles also find their homes in estuaries due to the sheer selection of marine life that they get to feast on. Hence, estuarine ecosystems are well balanced and sustainable.

Did You Know...

There is limited information on the second largest estuary in the world and its name. Some the Chesapeake Bay is considered the third-largest or the second largest estuary in the world.

It is estimated that there are more than 1200 estuaries spanning 120 countries in the world!

Chesapeake Bay is the largest estuary in America.

The largest estuary in the world is the Lawrence River.