| A coral reef is the limestone skeleton of a colony of living animals, the corals. Reefs are more important for the earth’s ecological balance than was previously recognised – they function as regulators, both filtering seawater as well as providing it with fresh oxygen and other elements.
The reef is a rich and complex world, in which a large number of conditions need to be in balance if it is to thrive. Temperature, light, salinity, acidity, hardness, nitrite, nitrate and phosphate levels are some of the most important factors affecting the life of the reef. Corals can be roughly categorised into two types: hard and soft corals. Hard, reef-building corals, such as stone corals, have 6 tentacles (or multiples of 6), while soft corals have 8 tentacles (or multiples of 8). Living corals are dependent on zooxantelles, small algae inhabiting coral tissue. Using sunlight, the algae photosynthesize seawater, producing carbohydrates that nourish the coral host. This is why corals thrive in clear, sunlit water, relatively near the surface. Certain corals live as large, individual polyps, but mostly they are comprised of colonies of lesser polyps, which together constitute the coral. They may be either male or female, but often they are both. The members of the reef breed by simultaneously releasing their eggs and sperm into the water. After a period of a few hours to a few weeks, depending on the species and the circumstances, the larvae attach themselves to suitable surfaces and develop into polyps, colonizing the spaces around them. |
Henrik Franklin, a student at the University of Stockholm, is in association with Aquaria Water Museum engaged in a coral culturing project in an attempt to create alternative sources of livelihood in tropical coastal areas, as well as a method of rehabilitating threatened reefs.
Sustainable coral culturing is the theme of the project. It was initiated in 1994 with controlled attempts at rearing five species of coral off the coast of Zanzibar, Tanzania. There is great concern over reports from throughout the world of the destruction of coral reefs. The greatest threat is seen to be over-exploitation, which is related to the problem of population increase, especially in tropical developing countries. It is estimated that by the year 2000 approximately 75% of the human population will live along the coasts. This leads to an unsustainable exploitation of local natural resources, such as siltation, destructive fishing methods, limestone-mining of the reefs, tourism and an uncontrolled coastal development. Developing sustainable methods for the rearing of corals for export provides local inhabitants with an ecologically sound source of income. Instead of banning the trade in live corals, our project wishes to stimulate it, but only through the sale of cultured species. The health rather than the destruction of local reefs may thus increase in value. In our coral reef exhibits we wish to show that aquariums are an excellent way of stimulating interest and awareness in the world of corals. There is no better biology lesson than a living coral reef aquarium! |