Estuarine habitat is a body of water formed at the coast as a result of the action of tides which mix salt water from sea with fresh water from the land. The mixing of salt water and fresh water results in the formation of a brackish water. This brackish water is what is called estuarine.

Characteristics of Estuarine Habitats

The followings are the characteristics of the estuarine habitats:

Fluctuation in salinity: Salinity fluctuates in this habitat. Salinity is lower at the mouth of a river and gets higher towards the sea. Salinity is also affected by season. While rainy season reduces salinity due to addition of fresh water, dry season increases it.

Turbidity: Turbidity of estuarine habitat increases especially during the rainy season when lots of debris is brought down by rivers to the habitat. This high turbidity also reduces the rate of photosynthesis and respiration by organisms

Shallowness of water: Unlike the sea water which is deep, the water in estuarine habitat is very shallow

Low species diversity: The estuarine habitat has low diversity of species compared to marine habitat. Common plant species are phytoplanktons algae, marsh vegetation, etc. while animal species are crabs, oysters, lobsters, fishes, etc.

Water is affected by tides: Sea water usually flows rapidly into estuaries at high tides and rushes back into the ocean at low tides

High level of nutrients: The estuarine habitat contains abundant nutrients especially the organic detritus which form the bulk of producers in the habitat

Low oxygen content: Oxygen content of estuarine habitat is generally very low and as a result, much of the microbiological activities are anaerobic.

Types of Estuaries

Estuary is found in the following bodies of water

  • Delta: A delta is where a river divides into many channels before entry into the ocean or sea. Brackish water or estuary (delta) is formed at the mouth of a river as it enters the sea
  • Lagoon: Lagoon is a body of ocean water that enters into the land through a canal and therefore has the opportunity of mixing with fresh water from rivers and streams
  • Bay: Bay is a little or small portion of the sea water which enters into the land and mixes up with fresh water from rivers and streams. It should be noted that a lagoon is bigger than a bay and it may be long enough to join the sea at another end while bay is very small and not long enough to rejoin the sea in another end…

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