Calculations are made on the proportions of the total border lengths exhibiting growth, the proportions exhibiting retreat, and proportions exhibiting no change. To monitor upward growth of coral, spikes are implanted in living coral tissues on the coral heads. Measurements are taken during the next sampling period and comparisons made to calculate the rate of growth. Differences between periods are evaluated, as well as trends through time. Another methodology used for measuring accretionary growth data is to take cores from living coral colonies.
Growth is determined directly by measuring bands found the coral skeletons.
These annual bands are produced because the rate of calcium carbonate deposition by the corals varies on an annual cycle in response to environmental and physiological cycles. This method has the advantage of recording growth on the same colony from past decades so that comparisons can be made to current rates. In addition, this program has expanded the descriptive information of the banks and their surrounding environment. Most of the results discussed here are from the previously mentioned studies. A more recent continuing program was carried out by Continental Shelf Associates, Inc., and was completed in 1995.