Mass Coral Spawn
One of the wonders of the natural world is how creatures of utmost simplicity are able to undertake staggering feats of communication. Many of these feats are accomplished by marine creatures, but almost nothing is known about how they do it. An impressive example of communication and synchronization of marine creatures – and maybe the biggest sex event on the earth – is the mass spawning of the Great Barrier Reef, when hundreds of species of corals and other invertebrates cloud the sea with eggs and sperm during a few nights after the full moon in November each year.
This is the beginning of the coral life cycle; larvae hatch, develop and drift through the ocean while developing all the features to start life as a new baby coral. However, drifting larvae must settle, in other words, they must choose and attach themselves to a site where they can metamorphose and begin a sessile mode of life. Research has shown that larval settlement is a highly selective process which is guided by a range of signals which “tell” coral larvae where to settle. This involves signalling using various chemicals in complex pathways developed over millennia of evolution.
In collaboration with the Australian Institute of Marine Sciences in Townsville, Dr. Tilmann Harder and Jan Tebben of the University of NSW are studying the cues that guide coral larvae to suitable sites to settle and grow. These cues originate from certain bacteria attached to hard marine substrates and certain types of algae, referred to as crustose coralline algae. By running experiments which look at the settlement response of larvae when they are exposed to isolated molecules from bacteria and algae, researchers try to decipher the signalling compounds that play a very important role in the establishment of new coral reefs.
Read more in the November 2011 Sydney Morning Herald Feature.
