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News from the field 11.27.07
by Mary Hagedorn on November 18th, 2007
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The 2007 coral field seasons are over here in the Northern hemisphere, and it is time to reflect on what went right and what needs to be improved for next year’s conservation efforts. In 2007, we participated in a number of coral breeding events, two with Montipora capitata and three with Fungia scutaria here in Hawaii, and one breeding event with the endangered Elkhorn coral, Acropora palmata, in Puerto Rico.
Working on the endangered Elkhorn coral is such a challenge, not only because of the complex permitting process needed, but also because of the short time window we have available for research. In this species, live coral eggs and sperm are only available for two to three days a year. So this year, we tested the techniques we needed to apply to the Elkhorn coral on the Hawaiian coral species beforehand. This saved us a great deal of time in Puerto Rico and gave us some comparative data, as well.
Two of our major achievements this year with the endangered coral were, one, designing, building and testing new larval rearing chambers in collaboration with Mark Schick of the Shedd Aquarium and, two, successfully cryopreserving endangered Elkhorn coral sperm.
Why are these achievements important? Rearing larvae Elkhorn coral is not easy. We reared them in 2006 in low-tech bowls, but the cleaning and maintenance was a 24-hour job lasting 5 days. With this type of schedule, we could not really get any research done. The new larval rearing chambers worked beautifully! They kept the buoyant Elkhorn larvae moving gently in the water column, resulting in very low larval mortality. When coupled with our newly built flow-through system, this eliminated the long hours of stirring, cleaning and changing water in the larval rearing bowls, freeing up our time for more research and collection. This is a major advance in coral husbandry, and has already been used successfully by other groups rearing coral larvae in Florida.
The cryopreservation of coral sperm is important because many populations of Elkhorn coral are no longer reproducing sexually. This is because many of the existing Elkhorn populations are groupings of clones, meaning they are fragments from a few individuals that broke off and grew into a new genetically identical adult. Because these populations basically represent one genetic individual, they cannot self-fertilize. So when they produce eggs and sperm, it generally dies. However, if we could introduce some frozen and thawed sperm from some new individuals, this might help invigorate the genetic diversity of our coral, and prevent the extinction of this species. Next year, we need to actually test whether we can produce viable larvae with our frozen sperm.
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