MEPS 166:109-118 (1998)  -  doi:10.3354/meps166109

The potential of the massive reef building coral Siderastrea siderea to be a reliable archive of past environmental variations was investigated by means of a field experiment conducted on a fringing reef in Panama. Over a 14 mo experimental period, 5 closely spaced and shallow subtidal coral colonies were cored at 1 mo intervals. These cores were subsequently analysed to determine linear extension (growth) and the δ¹³C and δ¹⁸¹⁸O showed the strongest correlation with this seasonal cycle. The seasonal variations in skeletal δ¹⁸O are attributed to changes in SST (accounting for ca 60% of the δ¹⁸O signal) and inferred changes in water isotopic composition due to rainfall and runoff (ca 40% of the δ¹⁸O signal). Although these results indicate that this coral is capable of yielding high-resolution paleoenvironmental records from retrospective analysis of the skeleton, there were significant and unexplained between-colony differences in mean δ¹⁸O. Therefore, for this species of coral in this setting, great care must be taken before interpreting the regional environmental significance of either gradual changes in mean δ¹⁸O through the length of a single long coral core, or differences between modern and ancient (fossil) colonies. Although skeletal δ¹³C and growth rate did show some relatively weak but significant correlations with some of the environmental variables, especially when the records from all colonies were combined, it was concluded that these attributes have relatively low potential for regional paleoenvironmental reconstruction.

Coral skeleton · Stable isotopes · Panama · Reefs