ABSTRACT
The growth characteristics of Porites lutea skeleton in east sea area of Hainan Island were studied by CoralXDS software based on X-ray chronology. The growth parameters obtained included extension rate (ER), skeleton density (D), and calcification rate (CR). The results showed that ER varied from 0.49 to 1.10 cm·a-1 with an annual average of 0.76 cm·a-1, D varied from 1.11 to 1.35 g·cm-3 with an annual average of 1.22 g·cm-3, and CR varied from 0.55 to 1.41 g·cm-2·a-1 with an annual average of 0.94 g·cm-2·a-1. Statistical analyses indicated that sea surface temperature (SST) was the key environmental factor that controlled the growth characteristics, as it highly co-varied with ER and CR, less so with D. All of the three growth characteristics increased with the increase of SST. There were other factors that influenced the growth characteristics of the coral column, such as light, water salinity, and hydrodynamics, etc. In addition, typhoon and severe tropical storms also imposed a significant impact on the growth pattern of Porites lutea coral. The change in growth pattern of coral skeleton in east of Hainan Island was a response to complex climate fluctuation. Over the past century, SST of east Hainan Island dramatically increased at a rate of 0.15 â·(10 a)-1. The SST increase trend for the oceanic region could be divided into two stages, early 1940s and early 1980s. The human activities and global warming was the main causes for the increase of SST.
