Bar-Built Estuary Example — Reading Comprehension

A bar-built estuary is a type of estuary that forms when sandbars, barrier islands, or spits build up along the coastline. These natural barriers partially block the ocean’s water, creating a shallow lagoon where freshwater from rivers mixes with saltwater from the sea. Because of these sandbars, bar-built estuaries often look long and narrow, stretching behind beaches or islands.

One well-known example of a bar-built estuary is the Outer Banks of North Carolina. Along this area, barrier islands separate the Atlantic Ocean from the sounds (shallow lagoons) behind them, such as Albemarle Sound and Pamlico Sound. These estuaries are home to many species of fish, crabs, and birds.

Bar-built estuaries have several unique characteristics:

• They are usually shallow and can change shape after storms.
• Tides are weaker compared to other estuaries because sandbars block much of the ocean’s force.
• They provide important habitats for young fish, shellfish, and migrating birds.
• Marsh grasses grow along the edges, helping to filter pollution and protect the shoreline.

However, bar-built estuaries can also be fragile. Hurricanes or strong storms can break through the barrier islands, changing how water flows. Human development, such as building houses and roads along coasts, can also damage these ecosystems.

Fun Fact: Pamlico Sound in North Carolina, a bar-built estuary, is the largest lagoon along the U.S. East Coast!

What forms a bar-built estuary?

Which U.S. state has the Outer Banks?

What is Albemarle Sound?

Why are tides weaker here?

Which plants protect the shoreline?

What can change their shape?

Why are these estuaries fragile?

Largest lagoon on U.S. East Coast?