Coral reefs (continued)
By Marjorie Henry, Contributor

Samuel Cameron (left), second vice-president of St. Catherine Cooperative Credit Union and Betty Davis (second right), operation manager, chat with scholarship students (from left) Hope Graham, Janine Fisher and Marvin Thomas, during the St. Catherine Credit Union Scholarship Awards presentation at their office in Spanish Town, on Wednesday, August 31. - Rudolph Brown Photo

LAST WEEK, I started to share with you, information on Coral Reefs. I discussed the first Specific Objective as stated in the syllabus, that is, 'name, locate and describe the types of coral reefs found within the Caribbean.' May I encourage you to practise drawing and labelling the different types of reefs as done in the last lesson. Ever so often, whenever a question comes on this topic, you are asked to produce drawings of the reefs. Marks are allotted for a diagram well done and properly labelled.

SECOND SPECIFIC OBJECTIVE

Today I will continue the topic by focusing on the second Specific Objective, that is, 'describe the conditions necessary for successful coral reef formation.' In reference to the available textbooks, we are informed that corals have restricted habitats, thriving only under specific conditions. These are tabulated below:

1. Coral reefs can only survive in tropical and sub-tropical marine environments, 30 degrees north and south of the equator, where the sea temperature is between 23 and 25ºC. (Please note that the texts vary on this temperature. It may be safer to state that the temperature should be above 20ºC.). There are few coral reefs found outside the tropics, or where there are cold sea currents.

2. In saline water, for they cannot flourish in fresh water. Corals are absent, or few, in sea areas adjacent to debouching rivers which yield sediment and fresh water.

3. In clear, clean water which is free from sediment.

4. Coral grows only in fairly shallow water, in sea depths of about 55 metres (180 feet). Sunlight must be able to penetrate down to where coral is growing. They grow most luxuriantly near the sea surface where there is plenty of sunlight.

5. In water which is well supplied with oxygen and plankton. Corals flourish where the equatorial currents have become warmed and agitated and abundantly supplied with oxygen and food.

IMPORTANCE OF CORAL REEFS

Although not stated as one of the Specific Objectives for the topic, it is necessary to know about the importance of coral reefs, how they can be destroyed and what must be done to save them. In reference to the text, Caribbean Natural Landscape, we are informed that:

The environmental importance of Caribbean coral reefs has both a global and local component. Though their biomass is lower than forests, coral reefs play a similar role to forests in the maintenance of the planet's biosphere because they help remove carbon from the atmosphere and slow down the build-up of greenhouse gases. In the ocean, carbon is stored in the shells of marine animals and in the calcium carbonate of the reef structure.'

We are further informed of the importance of the coral reef ecosystems on the local scale. They have a value to society in two contrasting ways. 'Direct use values are the economic benefits derived from income-generating activities that take place in an ecosystem, such as fishing, tourism and recreation. Indirect use values or environmental services are the less tangible environmental benefits an ecosystem provides, such as protection against flood damage.'

The environmental services that coral reefs provide are taken from the same source and listed as follows:

* They protect coastlines against wave action, especially during storms
* They stabilise beaches against erosion
* They contribute to the formation of sandy beaches
* They are fish nurseries
* They are habitats for food sources such as molluscs and crustaceans

For additional information on the importance of coral reefs, refer to the New Caribbean Geography by Vohn A. M. Rahil.

* What are the activities that can lead to the destruction of the coral reefs?
* How can the coral reefs be saved?

Find the answers to these questions in your textbooks. The topic continues next week.