seainlets

Seainlets are narrow channels that connect the open sea with inland coastal waters such as lagoons, bays, or estuaries. They permit tidal exchange, flushing, and the movement of water, sediments, and organisms between the sea and connected basins. Seainlets can form naturally through coastal erosion, breaching of barrier structures, and long-term sediment transport, or they can be created or modified by humans to improve navigation, drainage, or flood management. They may be perennial or episodically open, depending on sedimentation and sea level.

The development of a seainlet often begins with the truncation of a coastal barrier by wave action or storm events, followed by tidal scouring and sediment removal that deepens a passage. Sediment supply, wave climate, and sea-level trends determine whether the inlet remains open or fills with sand. Once established, seainlets experience strong tidal currents, can migrate laterally, and may shift their position over time. Surrounding habitats often respond with changes in salinity, turbidity, and eelgrass or mangrove distribution.

Seainlets influence coastal ecology by enabling salinity gradients and nursery habitat connectivity. They support fish, invertebrates, and bird communities and can be important for nutrient cycling. For navigation and drainage, seainlets are often maintained via dredging or jetty construction, which can alter sediment dynamics and shoreline shape. Environmental planning typically weighs flood risk reduction against habitat preservation and sediment budgets.

See also: Inlet, estuary, tidal channel, lagoon.