Formation of functional coral clones through natural embryo fragmentation of broadcast spawn from the Great Barrier Reef

Acropora millepora colonies were collected from Trunk Reef in early December 2009 and maintained in the aquarium system at the Australian Institute of Marine Science. Eggs from 7 colonies were fertilized and after 3 hours, when the majority of embryos were at the 2, 4 or 8 cell stage, the embryos were gently poured twice over a vertical distance of 30 cm from one 2 litre plastic container to another. This caused embryos to fragment, with the resulting separated cells or groups of cells continuing on through normal development, but at smaller sizes than the original embryos. Embryos were cultured in three 40 l polypropylene tanks and 80% of the water was changed daily with 1 µm filtered seawater.After 7 days, a random sample of 35 larvae were measured and classified into three size classes. Fifteen randomly selected larvae were transferred with 10 ml of seawater into each well of four 6 well cell culture plates and exposed to the crustose coralline algae, Porolithon onkodes, to initiate metamorphosis.After 48 hours, newly settled juveniles were measured and classified into three size classes and the larval success of each size class determined. Four day old juvenile corals were inoculated with 10^5 cells/ml Symbiodinium sp. and symbiont uptake was observed after 6 weeks. Wind speed data for the predicted nights of annual broadcast spawning, for the years 2000 - 2010 were obtained from the AIMS weather stations located at Davies Reef, Myrmidon Reef, Hardy Reef and Magnetic Island. This laboratory study was undertaken to examine the viability of larvae derived from embryos fragmented by turbulence. In most metazoan sexual reproduction, the fertilized egg or early embryo is protected by a capsule or membrane. However, coral embryos from a range of families are an exception and lack this protection. Vulnerability to fragmentation had been observed when culturing coral embryos from the families Acroporidae, Faviidae, Mussidae, Fungidae and Occulinidae.