atóls

An atoll is a ring-shaped coral reef, island, or series of islets. It encircles a lagoon, which is a body of water. Atolls are typically found in tropical or subtropical oceans. They are formed over a period of time as a volcanic island gradually sinks or erodes. As the island sinks, coral reefs grow upwards around its edge. Eventually, the island may disappear entirely, leaving only the coral reef and the lagoon.

The lagoon at the center of an atoll can vary in depth and size. Some lagoons are shallow and connected to the open ocean by narrow channels, while others are deeper and more enclosed. The ring of the atoll itself can be made up of coral, sand, and vegetation. These islands are often low-lying and vulnerable to sea-level rise and storm surges.

Atolls are ecologically significant environments. The coral reefs provide habitats for a vast array of marine life, including fish, invertebrates, and algae. The lagoons can also support diverse ecosystems. Many atolls are home to unique flora and fauna, adapted to the specific conditions of these islands. They are also important resting and breeding grounds for migratory birds.

Geographically, atolls are most common in the Pacific Ocean, such as in the Maldives, Marshall Islands, and French Polynesia. They are also found in the Indian Ocean. The formation and existence of atolls are closely linked to geological processes and the health of coral reefs, making them sensitive indicators of environmental change. Their low elevation makes them particularly susceptible to the impacts of climate change.