CoastalKarst

Coastal karst is a form of karst landscape developed along coastlines where soluble rocks such as limestone or dolostone are dissolved by acidic groundwater and shaped by seawater. It forms when meteoric water recharges aquifers near the shore and interacts with tidal processes. Over long timescales, dissolution, wave action, and sea-level change produce a variety of coastal landforms.

Geology and processes: Carbonate dissolution occurs along fractures and bedding planes, enhanced by mixing of freshwater and seawater in anchialine settings. Sea-level fluctuations expose and submerge caves, creating sea caves, notches, arches, and coastal stacks. Anchialine caves host mixed-brackish groundwater ecosystems. Saltwater intrusion and wave action widen openings and connect nearshore aquifers to the sea.

Features and distribution: Typical landforms include sea caves, tidal notches, arches and stacks, coastal dolines, and extensive cave networks. Coastal karst occurs on limestone-dominated coasts worldwide, with notable regions such as Ha Long Bay in Vietnam, Phang Nga Bay in Thailand, the Algarve in Portugal, and various Caribbean and Mediterranean coastlines.

Ecology and conservation: Coastal karst aquifers support specialist subterranean ecosystems that rely on stable discharge and good water quality. These systems are vulnerable to pollution, groundwater over-extraction, sedimentation, and development. Tourism and exploration are common uses, requiring careful management, protective measures for recharge zones, and monitoring to preserve fragile habitats.