How do barrier islands and tidal inlets support the movement of organisms between lagoons and the open sea?

Barrier islands and tidal inlets are essential to the connectivity between lagoons and the open sea. While barrier islands act as protective features that separate lagoons from open marine conditions, they are typically punctuated by tidal inlets that facilitate the regular influx and egress of tidal waters.12

These inlets serve as the primary conduits for water circulation, allowing for the movement of organisms between the sheltered, productive lagoonal environment and the open ocean. The degree of this exchange is heavily influenced by the width of the inlets and the local tidal range. Within these channels, water velocities can become quite high, creating dynamic environments where only coarse sediment can settle, contrasting with the finer-grained, quieter conditions found elsewhere in the lagoon. By regulating the flow of water, these inlets maintain the necessary environmental conditions for the diverse flora and fauna that characterize these highly productive ecosystems.3241