Reef Life

Published on Gili Life

Connections and Relations in the Coral Reef

Coral reefs are some of the most diverse and productive ecosystems in the world, supporting an enormous community of life in and out of the water. In this varied community, the activity of each member influences and is influenced by the interaction with other species, which all are essential for the successful maintenance of life. From clear shallow waters to deeper and wider lagoons, the reef is a pool of interactions. If the balance of one or a group of related organisms is upset, the survival of the other is at risk.




What is the Coral Triangle?

The Coral Triangle is a bioregion comprising Southeast Asia up to Timor Leste and the Solomon Islands. This marine area hosts 37% of the world’s reef fish species, 76% of known coral species and is the world’s largest tuna nursery. The Coral Triangle provides shelter and food to the abundant marine life living in its waters and its resources directly and indirectly affect the livelihood of billions of people. The invaluable resources of this rich environment are currently at risk because of over-fishing, coastal development and pollution.

What is the Biorock®?

In order to protect the reef and its biodiversity around the Gili Islands, in 2004 the local environmental organisation Gili Eco Trust introduced the Biorock® technology. This innovative method was invented by Prof. Wolf Hilbertz and biologist Dr. Thomas J. Goreau and consists in using electrolysis to restore the coral reef. By applying low-voltage electrical current to live pieces of broken corals attached to a steel structure (the Biorock®), it has been observed that the coral survival rate increases and the reef is restored at a faster rate than in normal conditions. Thirteen years on, the Gili islands have become the largest Biorock® site in the world. For more information and to learn about Biorock® workshops in the Gili’s, write to GILILIFE-SEP-43-ReefLife3

Relationships in the Coral Reef

All sorts of plants and animals live in the coral reef and many species have evolved together and developed special relationships to help them survive. Some examples of relationship among reef organisms are:

Symbiosis: When two or more organisms live closely together; when one organism benefits from this relationship and the other one is neither helped nor harmed is called Commensalism; when both organism help each other is called Mutualism. When one organisms clearly take advantage of another organism, and this is harmed, is called Parasitism.

The clown fish and the sea anemone is a clear example of mutualism in the coral reef.

Crown-thorn sea stars have a parasitic relationship with corals, which they strip off their polyps for food.

Competition & Predation: Organisms can compete for space, for food or for reproduction.

Some sponges release toxins harmful to other sponges to gain space in the reef;

A predator – prey example is whale sharks preying on plankton and small fish





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