An Introduction to Coral Reefs:

Coral reefs are an important habitat that helps to support many diverse and productive marine communities. They have an extremely high biodiversity as they are home to over one million species.

Figure, 1. Image of the diverse array of organisms found at a reef. Courtesy of Richard Ling.

Figure, 1. Image of the diverse array of organisms found at a reef. Courtesy of Richard Ling.

At least 4,000 species of fish, which is equal to a quarter of all known fish species, are found on coral reefs (McAllister, 1991). Reefs are extremely productive ecosystems, with gross community productivity usually between 2.3 to 6.0g C m2 d-1.

Coral reefs are biogenic. This means they are built from living organisms. These can be a variety of organisms from coralline algae and sponges, to symbiotic zooxanthellae. Coralline algae and sponges contribute to reef development using a cementation process. They deposit calcium carbonate that forms limestone structures that increases the reef height . Growth is mainly driven by zooxanthellae, which are symbiotic algae that live in corals. The zooxanthellae aid the growth of hermatypic reefs by providing the coral with oxygen and nutrients and by increasing the calcification process (Goreau et al., 1979).

Figure, 3. Image courtesy of  U.S. Fish and Wildlife Service Southeast Region.

Figure, 2. Image of the Caribbean elkhorn coral Acropora palmata. Courtesy of U.S. Fish and Wildlife Service Southeast Region.

Overall growth is a balance between growth of the reef and bioerosion. Corals grow in high wave energy areas that allow strong waves to limit the growth of the reef. The Caribbean elkhorn coral Acropora palmata, can grow to be very large, some can extend to over 2 meters wide. This means they may feel the effects of strong wave action more and their growth could be limited. Figure 2 shows an image of the Caribbean elkhorn coral Acropora palmata. Its wide growth causes it to feel the effects of wave action heavily.

The aim of this blog is to give an insight into the interesting and diverse extreme habitat that is the coral reef. I will be focusing on the ecological importance and uses of coral reefs as well as the many threats that humans are imposing. There will be an insight into what the effects of anthropogenic activity are having on reefs at the moment, and what this could then lead to in terms of coral reef population abundance and diversity. So what does the future hold for this valuable ecosystem?

Next Page: Types of reef


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