Stony corals at Zoo-Aquarium
- View of the 11 m3 Great Coral Basin
With a total capacity of 25,000 litres twelve basins present different sections through the world of corals. The most impressive of these basins is the 11 m3 Great Coral Basin with its reproduction lagoon.
Here visitors can not only observe a large number of lower animals like sea urchins, reef mussels, crustaceans, and starfish, but also marvel at many colourful coral fish and, above all, the many different coral polyps. Since 1999 Zoo-Aquarium has redoubled its efforts to keep and breed stony corals and is now home to fifty four species of this animal class threatened everywhere in the world. Twenty-four species reproduce at regular intervals.
Stony coral polyps exude calcium carbonate to form their skeletons. This skeletal growth is boosted by symbiosis with single-celled algae, but this compels the animals to grow towards the sun if their algae are to receive enough light. Over time this calcium carbonate forms massive structures that turn to stone while a layer of living coral polyps continue to grow on the surface. This is how coral reefs are formed, and is incidentally the source of the name for stony corals.
It is especially the reef building corals that grow in areas where they compete for living space with macroalgae. When the conditions conducive to coral growth deteriorate the growth of algae takes over with a vengeance.
Coral reefs are threatened by overfishing, fishing with toxins and explosives, sedimentation, nutrient dumping from agri- and aquiculture, stress due to climatic fluctuations, predator population explosions, mass dying of algae grazers, and disease.
There is probably more than one factor that comes into effect at any one time, and often enough it is surely man that is the cause of this destruction to reefs. The successful keeping and breeding of stony corals at zoological institutes could become all the more significant in future for a better understanding of the reef dwellers and the conservation of their species.