Tuesday, June 10, 2014
Ideally, we could repeat our expedition year after year to see how calcification on the reef changes under different climate conditions. But I do need to write a thesis, so we need a different approach. One alternative is to use the growth histories preserved within the skeletons of massive corals living on Dongsha.
To access this information, we use underwater pneumatic drills to collect cores of skeleton from living coral colonies. Don't worry, we patch up the holes with cement and underwater epoxy and the coral grows over our plug in about a year. Back in Woods Hole, we send our cores through a CT scanner, which gives us a 3D map of skeletal density. Using software developed in our lab, we use the annual density banding to reconstruct coral growth rates in the past.
This information tells us how coral calcification on Dongsha changed during especially warm or cool years, or whether calcification is increasing or decreasing with time. Corals even form anomalous bands when they recover from bleaching, so we can tell when these corals have bleached in the past. How unusual is the bleaching event that we are seeing right now? Our cores will help answer that question.
- Tom DeCarlo
Joint Program in Oceanography
Woods Hole Oceanographic Institution