Which of the following is not listed as a barrier island component?

• A. Ocean beach
• B. Dunes
• C. Lagoons
• D. Coral reef

Answer: (D)

Barrier islands are long, narrow, sandy landforms that run parallel to the coast and are built and shaped by sediment movement. The main components you’d find on a barrier island include the ocean beach, which is the active, wave-pressed front; the dune system, formed by wind-blown sand and stabilized by vegetation to protect inland areas; and lagoons, which are shallow, sheltered waters behind the dunes that slow wave energy and host unique habitats. A coral reef sits offshore in warmer, tropical waters and is an offshore ecosystem, not a physical part of the barrier island itself. It can influence wave energy reaching the island, but it isn’t considered a component of the barrier island. So the coral reef is not a barrier island component.