Coral island

The structures also create calm zones in the ocean providing a place for fish and plant species to thrive.

Over geological time a reef may reach the surface and can become a coral island, where it begins a whole new ecosystem for land-based creatures.

The lagoon undergoes accretion and creates an island completely made of carbonate materials.

[6] The term "low island" refers to geologic origin rather than a strict classification of height.

Some low islands, such as Banaba, Makatea, Nauru, and Niue, rise several hundred feet above sea level, while numerous high islands (those of volcanic origin) rise a few feet above sea level, often classified as "rocks".

Atolls in the Atlantic are found in Colombia's Archipelago of San Andrés, Providencia and Santa Catalina.

Through chemical and physical changes humans can cause significant harm to reef systems and slow the creation of coral island chains.

By adding fertilizers into the water runoff, phytoplankton populations can explode and choke out coral reef systems.

[9] Low islands have poor, sandy soil and little fresh water, which makes them difficult to farm.