Corals live in colonies with their living tissue as a thin layer over their calcium carbonate exoskeleton. Feeding is achieved by the use of their tentacles and the principle diet is plankton. In most species, feeding is nocturnal since this is when reef plankton is most abundant. By using this feeding method, it is clear that there is a need for proper seawater circulation above and around the reef for the two-fold purpose of carrying out efficient gaseous exchange and efficient feeding.
The extensive coral reef structure is derived from hermatypic reef building corals, caIcareous algae and with sediments formed from their dead remains. Hermatypic corals deposit a heavy calcium carbonate skeleton and contain zooxanthellae. Both of these are essential in establishing the structural framework of the reef. Calcium and carbonate are obtained from food and by absorption from seawater. The zooxanthellae are symbiotic algae living in the tissues of the coral polyps, and the soluble metabolic products of photosynthesis produced by these symbionts pass directly into the coral tissue. The zooxanthellae intimately related to the rate of reef building in that they cause faster skeletal formation (calcification) during the day when photosynthesis occurs.
The effect of the reef building corals, calcareous algae and sediments formed from their dead remains result in the formation of a cemented, solid structure - the coral reef - which can take on various forms.
Fringing Reefs of Barbados
Fringing reefs are found around most tropical island systems. They develop close to these islands by the growth of corals and associated hydrozoans, alcyonarians and calcareous algae.
Fringing reefs are prevalent around Barbados and because of their location they are of great aesthetic value to the island. More importantly, their location makes them an important barrier for beach protection and stability.