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Sam DePutron Home Institution: University of Swansea in Wales Sam is a recipient of a Munson Foundation award for coral reef research as well as being a graduate intern at BBSR.
I study at the University of Swansea in Wales which is part of the United Kingdom. I first came to Bermuda in the summer of 1995 to carry out the research for my university undergraduate project. I worked here for 3 months and in that time I designed, constructed and built traps My trap was designed to catch the larve as they began to settle to the bottom and look for a place to live. The number of larvae that I caught was then compared with another study that was measuring the number of larvae that actually settle on the reef. Settlement is the final stage of the baby coral's journey and involves the larvae attaching itself to the bottom (on a piece of stone or old coral for example) and transforming into a polyp (this is called metamorphosis and is similar to what happens with tadpoles to frogs or moths to butterflies). This polyp will then grow by copying itself to form new individuals and a colony is formed. It was interesting to see that the number of baby coral larvae that I caught in my traps was a lot greater than the number of larvae that were found settled on the bottom. This is because coral larvae are very tasty to many of the reef animals such as zooplankton (Link to Astrids page) and so are eaten before the can settle. Other larvae may never find a suitable place to live before they run out of energy and so they die. Because of all of these dangers, an adult must produce many baby coral larvae so at least some of them will survive to start a new coral colony.After doing this initial study, I became fascinated with the life of these coral larvae that have such a hard time in the water finding somewhere to live and have to avoid lots of hungry predators. Various coral species have different methods, or strategies, for producing these larvae. Some corals will reproduce by the production of larvae over many months of the year. Others will reproduce for only limited periods. Different coral colonies of the same species will reproduce over precise days of the month and even at specific times. The corals coordinate this by the phase of the moon and by amounts of light.I returned back here to Bermuda in April 1998 to carry out postgraduate research for my Ph.D. I will spend some of my time at my home University of Swansea in Wales. However, most of my time will be spent here in Bermuda. Whilst I am no longer using my traps to try and catch the coral larvae, I am still investigating coral reproduction and the production of larvae. I mentioned how it is important that we know how corals reproduce. But for some species this is not known, or is not known in very much detail. Part of my job is to find out about the reproduction of these mysterious species. The second part of my job is to see if and how the reproductive cycle of some corals is different depending on where the coral colony lives. Here in Bermuda, some of the coral reefs are deeper than others. Some coral reefs are in areas of clear water while other corals live in murky waters that have a lot of sediment. These are examples of the different environmental conditions that corals can be exposed to. I have chosen to study 2 different animals from 3 different groups of coral. The first group is not really true corals. They are called Zoanthids. These animals belong to the same overall class as the corals but are in a separate group, as they look very different. There are not as many different types of zoanthids as there are true corals but these animals can occur in large numbers on the reefs. The species that I am studying are Zoanthus sociatusand Parazoanthus parasiticus which lives symbiotically, or with a sponge. Very little information is known of the reproductive biology of these species. Click on these images if you would like to see them larger; but they are about 500K files so it will take some time!).The other animals that I study are true corals. There are 2 major groups of true corals. These are the hard, stony corals (that are called scleractinians) and the soft corals (which are also called gorgonians or octocorals). The stony corals have hard skeletons made out of calcium carbonate whereas the soft corals have a flexible skeleton made out of a substance called gorgonin. [Link to coral biology section].One of the hard corals that I am studying is called Madracis mirabilis
The methods that I use to study the reproductive cycles of these species is to collect samples from the corals every other week by SCUBA diving and cut them up to see whether there are any female eggs or male spermaries (sacs of sperm) in the polyps. I will also be placing nets over the colonies underwater on the reefs to catch the larvae as they are released from the adult colonies. This will show me exactly when the species release the larvae. Also, I will take whole colonies from the reef and put them in tanks here in the lab in order to watch them more closely. I have sites set up on reefs all around Bermuda that vary in their environmental conditions. |