Knowra Coral island Coral island A low-lying island formed chiefly from coral reef material, often surrounding a lagoon. Many coral islands are atolls built on submerged volcanic foundations.
Atoll : A ring-shaped coral reef or island enclosing a lagoon, usually formed around a subsiding volcanic island. Many coral islands are atolls, with land built on the rim of an enclosed lagoon.
Lagoon : A shallow body of water separated from the open sea by a reef, barrier island, or other landform. A lagoon occupies the central water space enclosed by many atoll islands.
Freshwater lens : A body of fresh groundwater that floats above denser seawater within a permeable coastal aquifer. It is often the main natural freshwater source beneath a coral island.
King tides : Unusually high tides that occur when astronomical and local conditions combine to raise sea level. They can flood low-lying island land and contaminate freshwater even without a major storm.
Coral reef : A marine structure built mainly by the accumulated skeletons of reef-building corals and other organisms. Its living framework supplies much of the material from which coral islands develop.
Fringing reef : A coral reef that grows close to a shore, often extending from the coastline into shallow water. It is an early reef form in Darwin's model of atoll development.
Saltwater intrusion : The movement of saline water into freshwater aquifers, often following pumping or coastal flooding. It threatens the thin groundwater reserves on low-lying coral islands.
Climate change and small island states : The effects of climate change on small island countries, including sea-level rise, ocean warming, and extreme weather. Coral-island nations face these risks despite emissions originating largely elsewhere.
Darwin's theory of coral reef formation : Charles Darwin's explanation that reefs develop as volcanic islands subside, producing fringing reefs, barrier reefs, and atolls. It explains how an atoll's reef platform can grow upward as its volcanic foundation sinks.
Barrier reef : A coral reef separated from a coast by a lagoon or other broad stretch of water. It is an intermediate reef form in the subsidence sequence leading to an atoll.
Show all 24