An estuary is a partially enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries are dynamic ecosystems that are influenced by both freshwater and saltwater inputs, and they are home to a variety of plants and animals.

Brackish water is a mixture of freshwater and saltwater. It is typically found in estuaries, where freshwater from rivers and streams mixes with saltwater from the ocean. Brackish water can also be found in coastal lagoons, marshes, and swamps.

The salinity of brackish water ranges from 0.5 to 30 parts per thousand (ppt). This means that brackish water is less salty than seawater, which has a salinity of approximately 35 ppt.

Estuaries are typically shallow and have a muddy bottom. They have a strong tidal influence, which means that the water level rises and falls twice a day. Estuaries are often surrounded by salt marshes or mangroves, which are plants that are adapted to living in brackish water.

Estuaries are home to a variety of plants and animals, including fish, shellfish, crabs, shrimp, and birds. They are an important nursery ground for fish and shellfish, and they are a source of food for birds and other wildlife.

Estuaries are threatened by a variety of human activities, including pollution, habitat loss, and climate change. Pollution can come from a variety of sources, including sewage, industrial waste, and agricultural runoff. Habitat loss can occur when estuaries are filled in for development or when they are dredged for navigation. Climate change is causing sea levels to rise, which is threatening to inundate estuaries and destroy their habitats.

There are a number of things that can be done to protect estuaries, including reducing pollution, protecting habitats, and mitigating the effects of climate change. Reducing pollution can be done by improving wastewater treatment, reducing industrial waste, and reducing agricultural runoff. Protecting habitats can be done by restoring wetlands, creating marine protected areas, and regulating development in coastal areas. Mitigating the effects of climate change can be done by reducing greenhouse gas emissions and investing in renewable energy.

An estuary is a partially enclosed coastal body of water, while a salt marsh is a wetland that is dominated by salt-tolerant plants. An estuary is always connected to the ocean, while a salt marsh may or may not be connected to the ocean. An estuary is typically deeper than a salt marsh.

An estuary is a partially enclosed coastal body of water with a free connection to the open sea, while a lagoon is a body of water that is separated from the open sea by a barrier island or reef. An estuary is always connected to a river, while a lagoon may or may not be connected to a river. An estuary is typically larger than a lagoon.

An estuary is a partially enclosed coastal body of water with a free connection to the open sea, while a fjord is a long, narrow inlet of the sea that is surrounded by steep cliffs. An estuary is always connected to a river, while a fjord may or may not be connected to a river. An estuary is typically shallower than a fjord.

An estuary is a partially enclosed coastal body of water with a free connection to the open sea, while a delta is a fan-shaped deposit of sediment that is formed at the mouth of a river. An estuary is always connected to a river, while a delta may or may not be connected to a river. An estuary is typically larger than a delta.

An estuary is a partially enclosed coastal body of water with a free connection to the open sea, while a bay is a body of water that is partially enclosed by land. An estuary is always connected to a river, while a bay may or may not be connected to a river. An estuary is typically smaller than a bay.

An estuary is a partially enclosed coastal body of water with a free connection to the open sea, while a harbor is a body of water that is protected from the open sea by a breakwater or other structure. An estuary is always connected to a river, while a harbor may or may not be connected to a river. An estuary is typically larger than a harbor.

An estuary is a partially enclosed coastal body of water with a free connection to the open sea, while a sound is a body of water that is separated from the open sea by a narrow strip of land. An estuary is always connected to a river, while a sound may or may not be connected to a river. An estuary is typically larger than a sound.