Coral Reefs

According to the CSEC Syllabus, the specific objectives related to Coral Reefs are as follows:

Describe types of Coral Reefs
Describe the conditions necessary for the successful formation of Coral Reefs in the Caribbean
Explain the importance of Coral Reefs in the Caribbean.

As such, we will follow these objectives for this unit.

What are Coral reefs?

Coral Reefs are hard rocky ridges built up from the seabed by millions of tiny living coral organism. As these organisms grow, their exoskeleton (the hard stony feature we see) is what forms the reef itself.

Types of coral reefs

There are in fact three types of Coral Reefs found in the Caribbean. They are the following: Fringing Reefs, Barrier Reefs and Atoll Reefs.

Fringing Reefs - Fringing Reefs are shallow-water reefs that run roughly parallel to the coast. These types of reefs form overtime by the gradual accumulation of coral during long period of ideal environmental conditions. Often, a shallow lagoon is formed between the reef and the shore and this is usually rich in marine life. However, storms (such as Hurricanes which are frequent here in the Caribbean) occasionally break up fringing reefs to leave behind isolated reefs rather than a single continuous feature.

Diagram showing the formation of Fringing Reef (Taken from CSEC Geo Study Guide pg 89)

Barrier Reef - In contrast to Fringing Reefs, Barrier reefs have more extensive features than fringing reefs and are found further out at sea. The most famous example is Australia's Barrier Reef while the second largest in the world is 25km off the coast of Belize.

Barrier Reefs most likely begin life as fringing reefs. Overtime, (given climate change and other factors) a gradual rise in sea level over long periods of time flood the coastline creating a wide body of water between the shore and the reef. As the reef grows, it remains a distance away from the coast.

Diagram showing the formation of Barrier Reef (Taken from CSEC Geo Study Guide pg 89)

Atoll Reef - Unlike both the Barrier and Fringing Reefs, a coral atoll is an isolated, almost ciruclar, ring shaped reef with a deep lagoon in its centre. Coral atolls are largely concentrated in the Pacific and Indian Oceans, for example the Maldives.

Coral atolls usual form at extinct volcanoes (submarine seamounts) where the rim of the crater creates the shallow water conditions necessary for coral growth. The deep lagoon forms in the extinct volcano's crater or caldera. (For more information look back on the unit of Volcanoes and see the portion on Extinct volcanoes).

Diagram showing the formation of Atoll Reef (Taken from CSEC Geo Study Guide pg 89)

IDEAL CONDITIONS FOR coral reef FORMATION

Whilst coral are microorganisms, they are very fragile creatures that require certain conditions to grow effectively. These conditions are as follows:

Temperature - The most ideal temperature for for coral reef development is 23°C. However, coral can only live in seawater that has an average temperature of 18°C or more.
Salinity - Coral thrive best in open sea away from the freshwater found at the mouths of rivers because the right amount of salt is needed. These are saltwater creatures.
Light - Coral thrive in shallow conditions because the algae they feed on (they are herbivorous) requires light to photosynthesize.
Clear well-aerated water - Coral grow fastest where the currents can carry food to them. Polluted water, particularly if it contains lots of sediments, reduces light and affects the coral's ability to feed also limiting the oxygen levels in the water which can cause the coral to die.
Turbidity - Some water movement (turbidity/turbulence) is necessary to provide food and oxygenated water to the coral. However, strong currents agitate sediment and in turn, this reduced sunlight and smothers the coral preventing it from feeding and respiration (again, it is important to note that these are animals).
Presence of Beneficial algae and fish - Coral have a symbiotic (harmless) relationship with algae and fish. Algae live within the coral and provide it with food whilst fish sheltered in coral reefs and breed there. Sometimes, corals have been known to consume small fish.

importance of coral reefs

Coral Reef are one of the most important ecosystems that we have on the planet. Coral Reefs provide a wide variety of benefits to not just animals but numerous industries including fisheries and tourism. The main benefits of corals include:

Coastal Protection - In times of extreme weather conditions, coral reefs act as a buffer zone providing vital shoreline protection against storm surge and tsunami. Given the distance between the surface of the water and the coral reef being shallow, it forces waves to break early before reaching the mainland shore. This processed leads to a reduction in coastal erosion and reduces coastal flooding. Corals also provide sheltered conditions for the growth of mangrove forests, which themselves are important breeding grounds for fish.
Beach Development - The white sand discovered along the beaches of tropical coastlines are due in part to the erosion of coral reefs. (Also works because parrot fish eat the inedible coral exoskeleton, break it down and expel it as sand). Sometimes, the sand is extracted for the construction industry to make cement.
Ecological Benefits - Coral reefs serve as vital, diverse ecosystems that are important breeding ground for fish, offering shelter and food.
Socio-economic Benefits - For countries like those within the Caribbean, coral reef are not just for protection. They serve as commercial fishing grounds, providing over 25% of the catch for the fishing industry. They also serve as extremely popular tourist destinations, provide huge sources of income and employment for thousands of people. Millions of people travel yearly to the Caribbean just to enjoy it's tropical beaches and coral reefs especially if they live in regions where coral scarcely grow or are nonexistent.

So why should we care about any of these benefits? Well, to put it bluntly, given the growing effects of Climate Change, the increase in storm strength and the extensive coral bleaching that is being observed, we will be in dire situations. Situations like:

Loss of Fishing Industry - This means a humongous blow to not just the economy of developing countries but also a loss of jobs and food insecurity. Given that the fishing industry relies heavily on these ecosystems, the loss of them would mean that citizens would suffer as a source of income and food would have seemingly disappeared.
Exposed Coastlines - Yes, mangroves do also act as a buffer for storms but the first line of defense is Coral Reefs. With the loss of coral reefs, our coastline will remain exposed to the negative effects of storm surge from the increasing number of deadly storms being formed in recent times.
Loss of Revenue - Given that coral reefs are popular tourist attraction, their destruction would mean that we would lose the revenue gained from the influx of tourist seeking to explore these wonderful ecosystems. Which in turn leads to a loss of jobs in the tourism industry as there would be less need for workers when there is no demand.

Infographic showing how Climate Change affects Coral Reefs (Taken from TNC Coral Reef Report 2016)

Diagram showcasing the distribution of Coral Reefs around the Caribbean (Taken from CSEC Geo Study Guide pg 90)

EViDENCE OF CORAL REEF DESTRUCTION

The following images serve as a timelapse showing the destruction (collapse) of an Elkhorn Coral off the coast of Antigua and Barbuda over a 3 year span from Coral Bleaching and Seafloor Warming. Images taken from Ruleo Comacho (January 2025).

Stage 1

Coral showing slight signs of bleaching

Stage 2

Coral starting to break down

Stage 3

Coral practically destroyed (almost completely bleached)

Coral Reef Bleaching has become a huge issue globally. The following images were taken from the Institute of Marine Affairs, Trinidad and Tobago (conference held November 2024).

Coral Bleaching off the coast of Trinidad and Tobago

Tidbits on Coral reefs ABroad and locally

Infographic Sharing quick facts on the Great Barrier Reef, Australia

Coral Reef distribution around Antigua and Barbuda (Taken from the TNC Coral Reef Report pg 4, 2016)

Fun videos so that students could see the Coral Reefs fighting for territory.

Page updated

Google Sites

Report abuse