Coral reproduction- part I: Biology © 2009 coralscience.org

The husbandry of exotic marine species has seen dramatic changes over the past decades. In the 1950's, pioneers such as Lee Chin Eng still experimented with seaweeds and air stones, which have now been upgraded to computerised aquaria equipped with strong lighting, protein skimmers, calcium reactors and coolers. Nowadays, the husbandry of many coral and other invertebrate species has risen to a high level, allowing for survival and growth. The next step however, reproduction, is still a major hurdle for most marine species. Sexual reproduction is a key step in the husbandry of any species, and allows for generating genetic diversity. Closing the life cycle of corals is one of the main future challenges for marine aquarists. Currently, large numbers of fish, coral and other invertebrate species are exported annually for the American, European and Japanese markets. This trade however is far from sustainable. According to a recent UNEP-WCMC report, only 1 % of exported corals has been raised by mariculture or aquaculture1. This poses yet another challenge for coral reefs, aggravating current issues such as pollution, overfishing, habitat destruction, global warming and ocean acidification. Figure 1: Culturing corals in captivity will become increasingly important in the future. More and more zoos and public aquaria are trying to meet their demands by culturing corals behind the scenes (photograph: Tim Wijgerde, NAUSICAA, Boulogne-sur-mer, France). Coral reproduction- part I: Biology © 2009 coralscience.org The aquaculture of many marine (in)vertebrate species will have to be upscaled significantly over the following years, due to persisting demand for livestock. Quotas of wild-caught specimens, be it corals or fish, will have to be reduced to prevent permanent ecological damage to coral reefs. This change towards a more sustainable approach is already ongoing, and aquarium hobbyists play an important role in this process. Species such as clownfish and sea horses are bred regularly by specialists, who devote a great deal of time to this. Many corals are being fragmented and traded on internet fora and events, and this has led to many commonly available species in the trade. Biologically speaking, fragmentation of corals is a form of vegetative, or asexual reproduction