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Click below to go to the Cruise Logs - (photo credit: Lophelia Coral - Open-File Report 2008-1148 & OCS Study MMS 2008-015)

DISCOVRE 2009



Cruise Log: 12/01/2009    



Studies of growth and reproduction of the structure forming stony coral, Lophelia pertusa

Sandra Brooke

Figure 1: Fragments of Lophelia stained pink for the growth experiment (Credit: S. Ross UNCW) - click to enlarge
Figure 1: Fragments of Lophelia stained pink for the growth experiment (Credit: S. Ross UNCW) - click to enlarge
In the deep waters of the Atlantic off the coast of North Carolina and Florida, massive coral reefs provide habitat and feeding grounds for a vast number of fish and invertebrates. The reef structure was created by two species of stony coral, Lophelia pertusa and Enallopsammia profunda. These are both branching species that form large complex colonies, which grow over thousands of years into giant mounds known as 'bioherms'.

One aspect of our research is to determine how and when these corals reproduce. To do this, we are collecting small pieces of each coral species at different times of the year. This is an ongoing study, and samples are also being taken from the Gulf of Mexico and the fjords of Norway in an international collaborative effort.
Figure 2: One of the Landers being recovered after deployment on the seafloor (Credit: S. Ross UNCW) - click to enlarge
Figure 2: One of the Landers being recovered after deployment on the seafloor (Credit: S. Ross UNCW) - click to enlarge


We will also be setting up an experiment to study growth rates of Lophelia pertusa. This rather complicated study began during cruise in August, when we used the Johnson Sea-Link submersible to collect small pieces of Lophelia. For the last three months, we've kept those corals alive in cold tanks. Just before the cruise, we stained the coral fragments with a special compound that turns the coral skeleton pink (fig 1). Next, we'll be placing the corals on the seafloor so that they can grow under natural conditions. Since they live in deep cold water, these corals are very sensitive to the warm surface waters. To keep them cold and protect them from damage, the coral branches will be mounted on a series of small containers, which will be attached to our benthic Landers (fig 2).
Figure 3: New, white growth emerges from coral that was stained pink for a recent growth experiment in the Gulf of Mexico. Staining makes it possible for scientists to measure coral growth rates. (credit: S. Brooke OIMB) - click to enlarge
Figure 3: New, white growth emerges from coral that was stained pink for a recent growth experiment in the Gulf of Mexico. Staining makes it possible for scientists to measure coral growth rates. (credit: S. Brooke OIMB) - click to enlarge


Two Landers will be deployed during the cruise, one close to a coral mound and another on flat mud further from the mound. New growth will be the normal white color, which will contrast with the older pink growth, making it possible to clearly see how much the fragments have grown over their year on the seafloor (fig 3). The results of this experiment will tell us not only how much the corals grew, but whether corals in the two different areas grow at different rates. Other instruments on the Landers will measure environmental conditions such as temperature, current speed, and food supply, which will help us to understand any differences we see.

These kinds of studies are very important as they provide basic ecological information on how these coral ecosystems function, what kinds of conditions they need to thrive, and how quickly they may recover from natural or human damage.



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