The Atoll Reefs of Belize

Image: Marine biologist Anjani pilots the SVII along Glover's Reef.


Belize has three major atolls sitting off its coast: Turneffe Islands, Lighthouse Reef and Glover’s Reef. We are surveying reefs around all three atolls. As we have been surveying, we noticed that the atoll reefs are particularly healthy, which could be because they are further from the more populated mainland coast and human development.

What is an "atoll reef?"

Atoll reefs are interesting as they form differently to barrier reefs. Atoll reefs can form on extinct volcano walls or high bedrock plains sitting under the sea surface. Coral reefs grow on top of the bedrock, as the bedrock erodes over time the corals clamber to grow on top of one other (to stay near the light-rich sea surface). After a long period of time we are left with a ring of reef that encircles a deeper lagoon inside. Atolls are one of the oldest habitats in the ocean, taking 100,000 to 30,000,000 years to form. Small coral islands can even form inside these lagoons which can collect sand allowing plants to take root - the stuff of idyllic holiday postcards!

The three atolls in Belize have as much reef surface as the entire Belizean barrier reef which is keeping the team very busy. It will be particularly interesting to compare the health of these different reef types when looking at a region-wide data set of reef health in this area.