The coral reefs in the Caribbean sea are close to land and normally in rather shallow water, compared to the rest of the world. Almost 36 percent of the reefs can be found within one mile or so of the coastline of the islands and the mainland. They surround virtually all islands in the region, although the largest individual reefs are in the Bahamas. The reefs do not form long coherent stretches but are in sections, which puts their biodiversity under greater risk. While this makes the coral reefs accessible for locals and tourists, it also puts them under threat.
The reefs are not barrier reefs like the reefs in the Pacific Ocean. The coral is also are of another type, with a mix of sponges and coral that grow from the hard reef base. This makes them a habitat for many types of marine animals, which can conceal themselves among the different forms of coral. This, in turn, contributes to their value as tourist attractions.
The coral reefs, and diving among them, are a major draw for tourists to the Caribbean. Each year the sea life around the reefs is enjoyed by millions of tourists, in particular scuba divers and snorkelers. Beaches behind the reefs are even more important to the local economy and an even bigger attraction for tourists. The local cuisine makes heavy use of the fishes from the reefs, contributing to the tourist income. Given the importance of tourism to the economies of the Caribbean nations, estimating the value of the reefs as a source of tourism has become necessary. As an example, the World Resource Institute has concluded several studies in the area and estimates that, for the nation of Belize, coral reef tourism contributes between $125 and $175 million per year out of a GDP of $1.36 billion. In the US, estimates based on measurements of economic activity in the Palm Beach and Miami area show that reef-related activity generated an income of $4.4 billion and generated over 70,000 jobs in the region.
Some types of coral, most notably the "hard" coral, which is the foundation of the reef ecosystem, has declined more than 80 percent since 1975. This means that there is no new formation of the reefs and they become susceptible to erosion. One-third of all the coral reefs in the Caribbean are under medium or high threat. Why this happens is not clear. Global warming may be a contributing factor, the sea becoming too hot for the coral to breed. Symbiotic animals are also dying, perhaps for the same reason, or because of disease. Pollution is another contributor, since coral thrives in nutrient-free waters. Here, the tourism industry is partly to blame, as waste water from hotels and tourist attractions is released without treatment directly into the sea. Agricultural runoff also plays a part. Agricultural use has increased in the region as the population has continued to climb during the 20th century.
Conservation efforts are underway in most of the Caribbean countries. Most have set up marine reservations, which can be an effective conservation measure if they are policed efficiently. Some have gone further; in Belize, the coral reefs have become a UNESCO world heritage site. But researchers are not sure whether it is sufficient to protect only the part of the reefs that have the highest biodiversity, as recuperation may be helped by preserving "ordinary" parts of the reef as well. Nor is there agreement on how the reserves should be designed and whether creating artificial reefs (such as has been done by sinking New York subway cars that have finished their service around the Florida coast) actually helps the coral, even if they are a boon to other marine life.
