Solenastrea hyades

Stephanocoenia sp.) collected from Discovery Bay, Jamaica. Branching at about 25 cm from the top is clearly evident. Samples analyzed are designated with a letter and number, (b) Plot of activity of Ra/ Ra in the Jamaica coral head and the North Carolina coral (Solenastrea hyades) head vs. distance from outer surface. The estimated growth rates based on decay of excess Ra activity are 0.5 and 0.15 cm/yr, respectively. From Moore and Krishnaswami (1972). 

Moore and Krishnaswami (1972) studied the growth rate of head corals (Stephanocoenia sp. and Solenastrea hyades) by two radiometric methods. Assuming an initial incorporation of Ra (or b) to Ra, which has a long half-life (1600 years) as contrasted to Ra and Pb, they used the decay of the latter in the coral as an index of growth rate. Since Ra has a shorter half-life (5.77 years) than Pb (21 years), the presence of Ra would approach zero in the older areas of the coral, and if no additional material was incorporated into the coral, it would be measurable for about 30 years. The Pb would reach equilibrium with its parent, Ra, in older sections of the coral head. Figure 116 shows the procedure for sampling a coral head and the graphic results of the 2 Ra/ Ra ratio method. 

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See also in sourсe #XX -- [ , ]

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