Coral Reefs
Corals
Corals are structures built on a hard surface and found in oceans and lagoons. Many people think corals grow only in warm waters with plenty of sunlight. But some coral species also grow in cold, dark waters.
Are there different types of coral reef structures?
Yes, there are! The main types of coral reef structures are: the fringing reef, patch reef, barrier reef, atoll and bank or platform reef.
Let’s look at each one separately.
Fringing Reef
This type of reef is directly attached to the shore. Fringing reefs grow quickly in shallow water but their growth furtheraway from shore is slower. Fringing reefs have a shallow platform that spreads outward to a sharply defined edge. Imagine the reef like a shelve with an edge that drops down to the sea floor.
Patch Reef
Patch reefs communities are found in waters 10-30 feet in depth. The outer edge
of each patch reef is surrounded by a ring of sand. It is the feeding fish that
determine how wide this sand ring is. If the fish feel safe close to the reef
then the sand ring will be narrow. A wide ring of sand means that the feeding
fish feel safe further away from the reef. Each patch reef is different in size,
development, and species living on them. Mostly large colonies of star and brain
corals make up this reef type.
Barrier Reef
Barrier reefs are often some distance from the coast. Some barrier reefs are
attached to fringing reefs on shelving coastlines. In other cases these reefs
may have developed in offshore places. Sometimes a lagoon separates a barrier
reef from the coast.
Atoll
An atoll is formed when a reef grows in a pyramid shape, rather like a volcano. A lagoon forms in the center of the surrounding reef and smaller reefs may grow inside this lagoon.
Bank or Platform Reef
Bank reefs are found in deeper waters than the patch reefs of near-shore environments
at depths 20-60 feet. Bank reefs are significantly larger than patch reefs and
are common dive and snorkel destinations. Bank reefs also have high species diversity,
meaning many kinds of animals and plants live on and around this type of reef.
Bank reefs have something special called spur and groove patterns. The spur and
groove formation is made up of low ridges of corals (spurs) separated by sandy
bottom channels (grooves). The most commonly found corals are elkhorn, staghorn,
seafans, sea whips and brain corals.
